WorldWideScience

Sample records for carbon conversion efficiency

  1. Riverbed methanotrophy sustained by high carbon conversion efficiency

    OpenAIRE

    Trimmer, Mark; Shelley, Felicity C; Kevin J Purdy; Maanoja, Susanna T; Chronopoulou, Panagiota-Myrsini; Grey, Jonathan

    2015-01-01

    Our understanding of the role of freshwaters in the global carbon cycle is being revised, but there is still a lack of data, especially for the cycling of methane, in rivers and streams. Unravelling the role of methanotrophy is key to determining the fate of methane in rivers. Here we focus on the carbon conversion efficiency (CCE) of methanotrophy, that is, how much organic carbon is produced per mole of CH4 oxidised, and how this is influenced by variation in methanotroph communities. First...

  2. Riverbed methanotrophy sustained by high carbon conversion efficiency.

    Science.gov (United States)

    Trimmer, Mark; Shelley, Felicity C; Purdy, Kevin J; Maanoja, Susanna T; Chronopoulou, Panagiota-Myrsini; Grey, Jonathan; Jonathan, Grey

    2015-10-01

    Our understanding of the role of freshwaters in the global carbon cycle is being revised, but there is still a lack of data, especially for the cycling of methane, in rivers and streams. Unravelling the role of methanotrophy is key to determining the fate of methane in rivers. Here we focus on the carbon conversion efficiency (CCE) of methanotrophy, that is, how much organic carbon is produced per mole of CH4 oxidised, and how this is influenced by variation in methanotroph communities. First, we show that the CCE of riverbed methanotrophs is consistently high (~50%) across a wide range of methane concentrations (~10-7000 nM) and despite a 10-fold span in the rate of methane oxidation. Then, we show that this high conversion efficiency is largely conserved (50%± confidence interval 44-56%) across pronounced variation in the key functional gene (70 operational taxonomic units (OTUs)), particulate methane monooxygenase (pmoA), and marked shifts in the abundance of Type I and Type II methanotrophs in eight replicate chalk streams. These data may suggest a degree of functional redundancy within the variable methanotroph community inhabiting these streams and that some of the variation in pmoA may reflect a suite of enzymes of different methane affinities which enables such a large range of methane concentrations to be oxidised. The latter, coupled to their high CCE, enables the methanotrophs to sustain net production throughout the year, regardless of the marked temporal and spatial changes that occur in methane. PMID:26057842

  3. Temperature responses of substrate carbon conversion efficiencies and growth rates of plant tissues.

    Science.gov (United States)

    Hansen, Lee D; Thomas, Nathan R; Arnholdt-Schmitt, Birgit

    2009-12-01

    Growth rates of plant tissues depend on both the respiration rate and the efficiency with which carbon is incorporated into new structural biomass. Calorespirometric measurement of respiratory heat and CO2 rates, from which both efficiency and growth rate can be calculated, is a well established method for determining the effects of rapid temperature changes on the respiratory and growth properties of plant tissues. The effect of the alternative oxidase/cytochrome oxidase activity ratio on efficiency is calculated from first principles. Data on the temperature dependence of the substrate carbon conversion efficiency are tabulated. These data show that epsilon is maximum and approximately constant through the optimum growth temperature range and decreases rapidly as temperatures approach temperature limits to growth. The width of the maximum and the slopes of decreasing epsilon at high and low temperatures vary greatly with species, cultivars and accessions.

  4. Carbon nanotube-amorphous silicon hybrid solar cell with improved conversion efficiency

    Science.gov (United States)

    Funde, Adinath M.; Nasibulin, Albert G.; Gufran Syed, Hashmi; Anisimov, Anton S.; Tsapenko, Alexey; Lund, Peter; Santos, J. D.; Torres, I.; Gandía, J. J.; Cárabe, J.; Rozenberg, A. D.; Levitsky, Igor A.

    2016-05-01

    We report a hybrid solar cell based on single walled carbon nanotubes (SWNTs) interfaced with amorphous silicon (a-Si). The high quality carbon nanotube network was dry transferred onto intrinsic a-Si forming Schottky junction for metallic SWNT bundles and heterojunctions for semiconducting SWNT bundles. The nanotube chemical doping and a-Si surface treatment minimized the hysteresis effect in current-voltage characteristics allowing an increase in the conversion efficiency to 1.5% under an air mass 1.5 solar spectrum simulator. We demonstrated that the thin SWNT film is able to replace a simultaneously p-doped a-Si layer and transparent conductive electrode in conventional amorphous silicon thin film photovoltaics.

  5. Carbon nanotube-amorphous silicon hybrid solar cell with improved conversion efficiency.

    Science.gov (United States)

    Funde, Adinath M; Nasibulin, Albert G; Syed, Hashmi Gufran; Anisimov, Anton S; Tsapenko, Alexey; Lund, Peter; Santos, J D; Torres, I; Gandía, J J; Cárabe, J; Rozenberg, A D; Levitsky, Igor A

    2016-05-01

    We report a hybrid solar cell based on single walled carbon nanotubes (SWNTs) interfaced with amorphous silicon (a-Si). The high quality carbon nanotube network was dry transferred onto intrinsic a-Si forming Schottky junction for metallic SWNT bundles and heterojunctions for semiconducting SWNT bundles. The nanotube chemical doping and a-Si surface treatment minimized the hysteresis effect in current-voltage characteristics allowing an increase in the conversion efficiency to 1.5% under an air mass 1.5 solar spectrum simulator. We demonstrated that the thin SWNT film is able to replace a simultaneously p-doped a-Si layer and transparent conductive electrode in conventional amorphous silicon thin film photovoltaics. PMID:27005494

  6. Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters

    OpenAIRE

    Samuel, Errol L. G.; Marcano, Daniela C.; Berka, Vladimir; Bitner, Brittany R.; Wu, Gang; Potter, Austin; Fabian, Roderic H.; Pautler, Robia G; Kent, Thomas A; Tsai, Ah-Lim; James M. Tour

    2015-01-01

    Mechanistic studies of nontoxic hydrophilic carbon cluster nanoparticles show that they are able to accomplish the direct conversion of superoxide to dioxygen and hydrogen peroxide. This is accomplished faster than in most single-active-site enzymes, and it is precisely what dioxygen-deficient tissue needs in the face of injury where reactive oxygen species, particularly superoxide, overwhelm the natural enzymes required to remove superoxide. We confirm here that the hydrophilic carbon cluste...

  7. Efficient near-infrared up-conversion photoluminescence in carbon nanotubes

    OpenAIRE

    Akizuki, Naoto; Aota, Shun; Mouri, Shinichiro; Matsuda, Kazunari; Miyauchi, Yuhei

    2015-01-01

    Photoluminescence phenomena normally obey Stokes' law of luminescence according to which the emitted photon energy is typically lower than its excitation counterparts. Here we show that carbon nanotubes break this rule under one-photon excitation conditions. We found that the carbon nanotubes exhibit efficient near-infrared photoluminescence upon photoexcitation even at an energy lying >100–200 meV below that of the emission at room temperature. This apparently anomalous phenomenon is attribu...

  8. Efficient Conversion of Carbon Dioxide into Methane using 3rd Generation Ionic Liquids Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This work directly addresses a technology of interest listed in Section 9, sub-section H1.01 In-Situ Resource Utilization, specifically "Highly efficient reactors...

  9. Enzymatic conversion of carbon dioxide.

    Science.gov (United States)

    Shi, Jiafu; Jiang, Yanjun; Jiang, Zhongyi; Wang, Xueyan; Wang, Xiaoli; Zhang, Shaohua; Han, Pingping; Yang, Chen

    2015-10-01

    With the continuous increase in fossil fuels consumption and the rapid growth of atmospheric CO2 concentration, the harmonious state between human and nature faces severe challenges. Exploring green and sustainable energy resources and devising efficient methods for CO2 capture, sequestration and utilization are urgently required. Converting CO2 into fuels/chemicals/materials as an indispensable element for CO2 capture, sequestration and utilization may offer a win-win strategy to both decrease the CO2 concentration and achieve the efficient exploitation of carbon resources. Among the current major methods (including chemical, photochemical, electrochemical and enzymatic methods), the enzymatic method, which is inspired by the CO2 metabolic process in cells, offers a green and potent alternative for efficient CO2 conversion due to its superior stereo-specificity and region/chemo-selectivity. Thus, in this tutorial review, we firstly provide a brief background about enzymatic conversion for CO2 capture, sequestration and utilization. Next, we depict six major routes of the CO2 metabolic process in cells, which are taken as the inspiration source for the construction of enzymatic systems in vitro. Next, we focus on the state-of-the-art routes for the catalytic conversion of CO2 by a single enzyme system and by a multienzyme system. Some emerging approaches and materials utilized for constructing single-enzyme/multienzyme systems to enhance the catalytic activity/stability will be highlighted. Finally, a summary about the current advances and the future perspectives of the enzymatic conversion of CO2 will be presented. PMID:26055659

  10. Carbon dioxide conversion over carbon-based nanocatalysts.

    Science.gov (United States)

    Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2013-07-01

    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity. PMID:23901504

  11. Study on carbon dioxide conversion by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Hyun; Park, Geun Il; Cho, Il Hoon; Choi, Sang Do; Hong, Kwang Hee; Lee, Chang Woo

    1999-09-01

    This study was carried out to investigate the synergistic effects on the CO{sub 2} conversion by the application of semiconductor in the field of gamma-ray. Gamma-ray irradiation was performed to examine the effects of semiconductor application on CO{sub 2} conversion in water and the formation of organic material from carbonate solution. From experimental results it is clear that the supplication of semiconductor in the field of gamma-ray increases the efficiency for CO{sub 2} conversion to organic matter. Based on the obtained experimental results it is obvious that the synergistic effects of semiconductor materials in the gamma-ray field leads to increase of the CO{sub 2} conversion yield to organic matter up to 50 percent compared to the gamma-ray irradiation. The way of achieving higher activity is due to thecatalytic action of semiconductor by gamma-ray irradiation. Zr-doped TiO{sub 2} catalyst prepared by sol-gel method exhibits the higher efficiency for CO{sub 2} conversion in aqueous solution and carbonate containing solution. This effect of Zr-doping can be explained by the formation of additional defects in surface of TiO{sub 2} film. (author)

  12. Study on carbon dioxide conversion by radiation

    International Nuclear Information System (INIS)

    This study was carried out to investigate the synergistic effects on the CO2 conversion by the application of semiconductor in the field of gamma-ray. Gamma-ray irradiation was performed to examine the effects of semiconductor application on CO2 conversion in water and the formation of organic material from carbonate solution. From experimental results it is clear that the supplication of semiconductor in the field of gamma-ray increases the efficiency for CO2 conversion to organic matter. Based on the obtained experimental results it is obvious that the synergistic effects of semiconductor materials in the gamma-ray field leads to increase of the CO2 conversion yield to organic matter up to 50 percent compared to the gamma-ray irradiation. The way of achieving higher activity is due to the catalytic action of semiconductor by gamma-ray irradiation. Zr-doped TiO2 catalyst prepared by sol-gel method exhibits the higher efficiency for CO2 conversion in aqueous solution and carbonate containing solution. This effect of Zr-doping can be explained by the formation of additional defects in surface of TiO2 film. (author)

  13. High-efficiency intermediate temperature solid oxide electrolyzer cells for the conversion of carbon dioxide to fuels

    Energy Technology Data Exchange (ETDEWEB)

    Yan , Jingbo; Chen, Hao; Dogdibegovic, Emir; Stevenson, Jeffry W.; Cheng, Mojie; Zhou, Xiao-Dong

    2014-04-15

    Electrochemical reduction of carbon dioxide in the intermediate temperature region was investigated by utilizing a reversible solid oxide electrolysis cell (SOEC). The current potential (i-V) curve exhibited a nonlinear characteristic at low current density. Differentiation of i-V curves revealed that the cell area specific resistance (ASR) was current-dependent and had its maximum in electrolysis mode and minimum in fuel cell mode. Impedance measurements were performed under different current densities and gas compositions, and the results were analyzed by calculating the distribution of relaxation times. The ASR variation resulted from the difference in electrochemical reactions occurring on the Ni-YSZ electrode, i.e., Ni-YSZ is a better electrode for CO oxidation than for CO2 reduction. Coke formation on Ni-YSZ played a crucial role in affecting its electrolysis performance in the intermediate temperature region. The ASR apex was associated with a decrease in cell temperature during electrolysis due to the endothermic nature of CO2 reduction reaction. It was postulated that such a decrease in temperature and rise in CO concentration led to coke formation. As a consequence, higher temperature (>700 degrees C), higher CO2 concentration (>50%), and the presence of hydrogen or steam are recommended for efficient CO2 reduction in solid oxide electrochemical cells. (C) 2013 Elsevier B.V. All rights reserved

  14. Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

    Science.gov (United States)

    Kofuji, Yusuke; Isobe, Yuki; Shiraishi, Yasuhiro; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Hirai, Takayuki

    2016-08-10

    Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts. PMID:27439985

  15. Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

    Science.gov (United States)

    Kofuji, Yusuke; Isobe, Yuki; Shiraishi, Yasuhiro; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Hirai, Takayuki

    2016-08-10

    Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.

  16. Electrocatalysts for carbon dioxide conversion

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard I; Salehi-Khojin, Amin

    2015-04-21

    Electrocatalysts for carbon dioxide conversion include at least one catalytically active element with a particle size above 0.6 nm. The electrocatalysts can also include a Helper Catalyst. The catalysts can be used to increase the rate, modify the selectivity or lower the overpotential of electrochemical conversion of CO.sub.2. Chemical processes and devices using the catalysts also include processes to produce CO, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  17. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

    Science.gov (United States)

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E; Liu, Tianxi

    2016-01-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications. PMID:27511271

  18. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion.

    Science.gov (United States)

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E; Liu, Tianxi

    2016-01-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications. PMID:27511271

  19. Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

    Science.gov (United States)

    Huang, Yunpeng; Lai, Feili; Zhang, Longsheng; Lu, Hengyi; Miao, Yue-E.; Liu, Tianxi

    2016-08-01

    Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications.

  20. The Carbon Nanotube Fibers for Optoelectric Conversion and Energy Storage

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2014-01-01

    Full Text Available This review summarizes recent studies on carbon nanotube (CNT fibers for weavable device of optoelectric conversion and energy storage. The intrinsic properties of individual CNTs make the CNT fibers ideal candidates for optoelectric conversion and energy storage. Many potential applications such as solar cell, supercapacitor, and lithium ion battery have been envisaged. The recent advancement in CNT fibers for optoelectric conversion and energy storage and the current challenge including low energy conversion efficiency and low stability and future direction of the energy fiber have been finally summarized in this paper.

  1. Conversion efficiency in a solar splitting system

    International Nuclear Information System (INIS)

    In this paper we report on concentrator photovoltaic system made by splitting the solar system based on separate Si, GaAs, and InGaN solar cells. The SSCPV module was fabricated and conversion efficiency up to 24.8% was achieved for the concentration factor of 12.8 that is in correlation with theoretical predictions

  2. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. PMID:25708541

  3. Carbon-based electrocatalysts for advanced energy conversion and storage

    OpenAIRE

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER ...

  4. Efficient biological conversion of carbon monoxide (CO) to carbon dioxide (CO2) and for utilization in bioplastic production by Ralstonia eutropha through the display of an enzyme complex on the cell surface.

    Science.gov (United States)

    Hyeon, Jeong Eun; Kim, Seung Wook; Park, Chulhwan; Han, Sung Ok

    2015-06-25

    An enzyme complex for biological conversion of CO to CO2 was anchored on the cell surface of the CO2-utilizing Ralstonia eutropha and successfully resulted in a 3.3-fold increase in conversion efficiency. These results suggest that this complexed system may be a promising strategy for CO2 utilization as a biological tool for the production of bioplastics. PMID:26017299

  5. Efficient biological conversion of carbon monoxide (CO) to carbon dioxide (CO2) and for utilization in bioplastic production by Ralstonia eutropha through the display of an enzyme complex on the cell surface.

    Science.gov (United States)

    Hyeon, Jeong Eun; Kim, Seung Wook; Park, Chulhwan; Han, Sung Ok

    2015-06-25

    An enzyme complex for biological conversion of CO to CO2 was anchored on the cell surface of the CO2-utilizing Ralstonia eutropha and successfully resulted in a 3.3-fold increase in conversion efficiency. These results suggest that this complexed system may be a promising strategy for CO2 utilization as a biological tool for the production of bioplastics.

  6. Efficient quantum computing using coherent photon conversion

    CERN Document Server

    Langford, N K; Prevedel, R; Munro, W J; Milburn, G J; Zeilinger, A

    2011-01-01

    Single photons provide excellent quantum information carriers, but current schemes for preparing, processing and measuring them are inefficient. For example, down-conversion provides heralded, but randomly timed single photons, while linear-optics gates are inherently probabilistic. Here, we introduce a deterministic scheme for photonic quantum information. Our single, versatile process---coherent photon conversion---provides a full suite of photonic quantum processing tools, from creating high-quality heralded single- and multiphoton states free of higher-order imperfections to implementing deterministic multiqubit entanglement gates and high-efficiency detection. It fulfils all requirements for a scalable photonic quantum computing architecture. Using photonic crystal fibres, we experimentally demonstrate a four-colour nonlinear process usable for coherent photon conversion and show that current technology provides a feasible path towards deterministic operation. Our scheme, based on interacting bosonic fie...

  7. Carbon aerogel electrodes for direct energy conversion

    Science.gov (United States)

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  8. Functionalization of graphene for efficient energy conversion and storage.

    Science.gov (United States)

    Dai, Liming

    2013-01-15

    As global energy consumption accelerates at an alarming rate, the development of clean and renewable energy conversion and storage systems has become more important than ever. Although the efficiency of energy conversion and storage devices depends on a variety of factors, their overall performance strongly relies on the structure and properties of the component materials. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. As a building block for carbon materials of all other dimensionalities (such as 0D buckyball, 1D nanotube, 3D graphite), the two-dimensional (2D) single atomic carbon sheet of graphene has emerged as an attractive candidate for energy applications due to its unique structure and properties. Like other materials, however, a graphene-based material that possesses desirable bulk properties rarely features the surface characteristics required for certain specific applications. Therefore, surface functionalization is essential, and researchers have devised various covalent and noncovalent chemistries for making graphene materials with the bulk and surface properties needed for efficient energy conversion and storage. In this Account, I summarize some of our new ideas and strategies for the controlled functionalization of graphene for the development of efficient energy conversion and storage devices, such as solar cells, fuel cells, supercapacitors, and batteries. The dangling bonds at the edge of graphene can be used for the covalent attachment of various chemical moieties while the graphene basal plane can be modified via either covalent or noncovalent functionalization. The asymmetric functionalization of the two opposite surfaces of individual graphene sheets with different moieties can lead to the self-assembly of graphene sheets into hierarchically structured materials. Judicious

  9. Efficient quantum computing using coherent photon conversion.

    Science.gov (United States)

    Langford, N K; Ramelow, S; Prevedel, R; Munro, W J; Milburn, G J; Zeilinger, A

    2011-10-12

    Single photons are excellent quantum information carriers: they were used in the earliest demonstrations of entanglement and in the production of the highest-quality entanglement reported so far. However, current schemes for preparing, processing and measuring them are inefficient. For example, down-conversion provides heralded, but randomly timed, single photons, and linear optics gates are inherently probabilistic. Here we introduce a deterministic process--coherent photon conversion (CPC)--that provides a new way to generate and process complex, multiquanta states for photonic quantum information applications. The technique uses classically pumped nonlinearities to induce coherent oscillations between orthogonal states of multiple quantum excitations. One example of CPC, based on a pumped four-wave-mixing interaction, is shown to yield a single, versatile process that provides a full set of photonic quantum processing tools. This set satisfies the DiVincenzo criteria for a scalable quantum computing architecture, including deterministic multiqubit entanglement gates (based on a novel form of photon-photon interaction), high-quality heralded single- and multiphoton states free from higher-order imperfections, and robust, high-efficiency detection. It can also be used to produce heralded multiphoton entanglement, create optically switchable quantum circuits and implement an improved form of down-conversion with reduced higher-order effects. Such tools are valuable building blocks for many quantum-enabled technologies. Finally, using photonic crystal fibres we experimentally demonstrate quantum correlations arising from a four-colour nonlinear process suitable for CPC and use these measurements to study the feasibility of reaching the deterministic regime with current technology. Our scheme, which is based on interacting bosonic fields, is not restricted to optical systems but could also be implemented in optomechanical, electromechanical and superconducting

  10. Efficient conversion of dimethylarsinate into arsenic and its simultaneous adsorption removal over FeCx/N-doped carbon fiber composite in an electro-Fenton process.

    Science.gov (United States)

    Lan, Huachun; Li, Jianfei; Sun, Meng; An, Xiaoqiang; Hu, Chengzhi; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2016-09-01

    In this study, a FeCx/N-doped carbon fiber composite (FeCx/NCNFs) was developed via an electrospinning method. According to the characterization results of XRD, TEM and XPS, FeCx (a mixture of Fe7C3 and Fe3C) was either embedded in or attached to the NCNFs. It was used for the first time as a catalyst for dimethylarsinate (DMA) degradation and as an absorbent for inorganic arsenic (As (V)), with degradation and adsorption occurring simultaneously, in an electro-Fenton process. The effects of catalyst dosage, initial DMA concentration, solution pH, and applied current on the treatment efficiency and the corresponding H2O2 generation were systematically investigated. The results showed that DMA could be efficiently oxidized into As(V). 96% of DMA was degraded after reaction time of 360 min and the residual As(V) concentration in solution was below the allowable limit of 0.01 mg/L under the optimum treatment conditions. Based on an ESR and radical scavenger experiment, OH was proven to be the sole reactive oxygen species involved in the degradation process of DMA. DMA was oxidized to MMA as the primary oxidation product, which was subsequently oxidized to inorganic arsenic, As (V). TOC was also efficiently removed at the same time. The DMA removal mechanism for simultaneous degradation of dimethylarsinate and adsorption of arsenic over FeCx/NCNFs in the electro-Fenton process was also proposed based on the experimental results. PMID:27179339

  11. Active carbons from low temperature conversion chars

    International Nuclear Information System (INIS)

    Hulls obtained from the fruits of five tropical biomass have been subjected to low temperature conversion process and their chars activated by partial physical gasification to produce active carbons. The biomass are T. catappa, B. nitida, L leucophylla, D. regia and O. martiana. The bulk densities of the samples ranged from 0.32 g.cm3 to 0.52 g.cm3. Out of the samples T. catappa recorded the highest cellulose content (41.9 g.100g-1), while O. martiana contained the highest lignin content (40.7 g.100g-1). The ash of the samples were low (0.5 - 4.4%). The percentage of char obtained after conversion were high (33.7% - 38.6%). Active carbons obtained from T. catappa, D. regia and O. martiana, recorded high methylene blue numbers and iodine values. They also displayed good micro- and mesostructural characteristics. Micropore volume (Vmicro) was between 0.33cm3.g-1 - 0.40cm3.g-1, while the mesopore volume(Vmeso) was between 0.05 cm3.g-1 - 0.07 cm3.g-1. The BET specific surface exceeds 1000 m2.g-1. All these values compared favourably with high grade commercial active carbons. (author)

  12. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

    Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.

  13. Carbon dioxide conversion by means of coplanar dielectric barrier discharges

    Science.gov (United States)

    Schiorlin, Milko; Klink, Rouven; Brandenburg, Ronny

    2016-08-01

    To face the worldwide problem of anthropogenic carbon dioxide (CO2) emission new techniques have to be developed. One approach for carbon capture utilization (CCU) is the conversion of CO2 to more valuable chemicals, e.g., carbon monoxide (CO) by means of non-thermal plasma generated at ambient conditions and supplied by excess energy from renewable sources. This paper reports about the effect of the admixture of inert gases, namely nitrogen or argon to CO2 in a coplanar dielectric barrier discharge (DBD). Systematic experiments were conducted to investigate the effects of applied voltage, frequency, flowrate and CO2 concentration in the influent. The composition of products, energy efficiency and yield were determined. Within the investigated parameter ranges, the maximum conversion of CO2 to CO efficiency of 1% was achieved when the specific input energy was 190 J L-1, whereas the maximum CO yield of 0.7% was achieved when the specific input energy was 210 J L-1. In conclusion, the energy efficiency can be significantly increased by operating the plasma in a diluted CO2 gas. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  14. An efficient hydrogenation catalyst in sulfuric acid for the conversion of nitrobenzene to p-aminophenol: N-doped carbon with encapsulated molybdenum carbide.

    Science.gov (United States)

    Wang, Tao; Dong, Zhen; Cai, Weimeng; Wang, Yongzheng; Fu, Teng; Zhao, Bin; Peng, Luming; Ding, Weiping; Chen, Yi

    2016-08-23

    The transfer of catalytic function from molybdenum carbide to N-doped carbon has been tested by encapsulating molybdenum carbide with N-doped carbon using a one-pot preparation process. The outer layer of N-doped carbon, inert itself, exhibits high activity and excellent selectivity with molybdenum carbide as the catalyst for the hydrogenation of nitrobenzene to p-aminophenol in sulfuric acid.

  15. Efficiency of Conversational Activities in Class

    Institute of Scientific and Technical Information of China (English)

    弥忠全; 雷鸣

    2011-01-01

    In recent years, the theory of cooperation and conversational implicature, along with the theory of face, the principles of politeness and the theory of relevance, has been paid much attention in language teaching. From cognitive angle, all these theories

  16. Needs, resources and climate change: Clean and efficient conversion technologies

    KAUST Repository

    Ghoniem, Ahmed F.

    2011-02-01

    Energy "powers" our life, and energy consumption correlates strongly with our standards of living. The developed world has become accustomed to cheap and plentiful supplies. Recently, more of the developing world populations are striving for the same, and taking steps towards securing their future energy needs. Competition over limited supplies of conventional fossil fuel resources is intensifying, and more challenging environmental problems are springing up, especially related to carbon dioxide (CO 2) emissions. There is strong evidence that atmospheric CO 2 concentration is well correlated with the average global temperature. Moreover, model predictions indicate that the century-old observed trend of rising temperatures could accelerate as carbon dioxide concentration continues to rise. Given the potential danger of such a scenario, it is suggested that steps be taken to curb energy-related CO 2 emissions through a number of technological solutions, which are to be implemented in a timely fashion. These solutions include a substantial improvement in energy conversion and utilization efficiencies, carbon capture and sequestration, and expanding the use of nuclear energy and renewable sources. Some of these technologies already exist, but are not deployed at sufficiently large scale. Others are under development, and some are at or near the conceptual state. © 2010 Elsevier Ltd. All rights reserved.

  17. Thermal conversion of an Fe3O4@metal-organic framework: a new method for an efficient Fe-Co/nanoporous carbon microwave absorbing material

    Science.gov (United States)

    Zhang, Xingmiao; Ji, Guangbin; Liu, Wei; Quan, Bin; Liang, Xiaohui; Shang, Chaomei; Cheng, Yan; Du, Youwei

    2015-07-01

    A novel FeCo nanoparticle embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL < -10 dB which covers from 12.2 to 18 GHz can be obtained, and its minimum reflection loss and bandwidth (RL values exceeding -10 dB) are far greater than those of commercial carbonyl iron powder under a very low thickness (1-1.5 mm). This study not only provides a good reference for future preparation of carbon-based lightweight microwave absorbing materials but also broadens the application of such kinds of metal-organic frameworks. Electronic supplementary information (ESI) available: Additional TEM image, SEM images, elemental mapping, Raman spectrum, dielectric loss tangent, magnetic loss tangent, and values of μ''(μ')-2f-1. See DOI: 10.1039/c5nr03176a

  18. Carbon Efficient Building Solutions

    Directory of Open Access Journals (Sweden)

    Pellervo Matilainen

    2010-03-01

    Full Text Available Traditionally, the Finnish legislation have focused on energy use and especially on energy used for heating space in buildings. However, in many cases this does not lead to the optimal concept in respect to minimizing green house gases. This paper studies how CO2 emission levels are affected by different measures to reduce energy use in buildings. This paper presents two real apartment buildings with different options of energy efficiency and power sources. The calculations clearly show that in the future electricity and domestic hot water use will have high importance in respect to energy efficiency, and therefore also CO2 equivalent (eq emissions. The importance increases when the energy efficiency of the building increases. There are big differences between average Finnish production and individual power plants; CO2 eq emissions might nearly double depending on the energy source and the power plant type. Both a building with an efficient district heating as a power source, and a building with ground heat in addition to nuclear power electricity as a complimentary electricity source performed very similarly to each other in respect to CO2 eq emissions. However, it is dangerous to conclude that it is not important which energy source is chosen. If hypothetically, the use of district heating would dramatically drop, the primary energy factor and CO2 eq emissions from electricity would rise, which in turn would lead to the increase of the ground heat systems emissions. A problem in the yearly calculations is that the fact that it is very important, sometimes even crucial, when energy is needed, is always excluded.

  19. Increased accumulation of polyhydroxybutyrate in divergent cyanobacteria under nutrient-deprived photoautotrophy: An efficient conversion of solar energy and carbon dioxide to polyhydroxybutyrate by Calothrix scytonemicola TISTR 8095.

    Science.gov (United States)

    Kaewbai-Ngam, Auratai; Incharoensakdi, Aran; Monshupanee, Tanakarn

    2016-07-01

    The cellular PHB content was determined in 137 strains of cyanobacteria representing 88 species in 26 genera under six photoautotrophic nutrient conditions. One hundred and thirty-four strains were PHB producers. The PHB contents of these 134 strains were subtle under normal growth condition, but were significantly increased in 63 strains under nitrogen deprivation (-N), a higher frequency than with phosphate and/or potassium and all-nutrient deprivation. A high PHB accumulation was not associated with any particular evolutionary groups, but was strain specific. The filamentous Calothrix scytonemicola TISTR 8095 produced 356.5±63.4mg/L PHB under -N from a biomass of 1396.6±66.1mg/L, giving a PHB content of 25.4±3.5% (w/w dry weight). This PHB productivity is equivalent to the CO2 consumption of 729.2±129.8mg/L. The maximum energy conversion from solar energy to PHB obtained by C. scytonemicola TISTR 8095 was 1.42±0.30%. PMID:27130227

  20. Increased accumulation of polyhydroxybutyrate in divergent cyanobacteria under nutrient-deprived photoautotrophy: An efficient conversion of solar energy and carbon dioxide to polyhydroxybutyrate by Calothrix scytonemicola TISTR 8095.

    Science.gov (United States)

    Kaewbai-Ngam, Auratai; Incharoensakdi, Aran; Monshupanee, Tanakarn

    2016-07-01

    The cellular PHB content was determined in 137 strains of cyanobacteria representing 88 species in 26 genera under six photoautotrophic nutrient conditions. One hundred and thirty-four strains were PHB producers. The PHB contents of these 134 strains were subtle under normal growth condition, but were significantly increased in 63 strains under nitrogen deprivation (-N), a higher frequency than with phosphate and/or potassium and all-nutrient deprivation. A high PHB accumulation was not associated with any particular evolutionary groups, but was strain specific. The filamentous Calothrix scytonemicola TISTR 8095 produced 356.5±63.4mg/L PHB under -N from a biomass of 1396.6±66.1mg/L, giving a PHB content of 25.4±3.5% (w/w dry weight). This PHB productivity is equivalent to the CO2 consumption of 729.2±129.8mg/L. The maximum energy conversion from solar energy to PHB obtained by C. scytonemicola TISTR 8095 was 1.42±0.30%.

  1. CONVERSION EFFICIENCY IMPROVEMENT FOR ENERGY CONSERVATION USING MATRIX CONVERTER

    OpenAIRE

    G.N. SURYA; SUBROTO DUTT

    2012-01-01

    Efficient conversion of electrical energy from one form to another has always been a fascinating domain for researchers. Right from the era of mercury arc rectifiers to present AC-DC-AC two stage converters and cycloconverters, efforts are consistently being laid to minimize the losses involved in conversion process. In the present study the AC-AC conversion topology known as Matrix Converter (MC), is modeled using MATLAB. Venturini’s simplified algorithm is used to determine the switch modul...

  2. Efficient frequency conversion based on local optimization theory

    Science.gov (United States)

    Xu, Lei; Chen, Changshui; Zhao, Xiangyang; Liu, Tuo; Hu, Hui

    2015-12-01

    We discuss theoretically a robustness of the difference frequency conversion method and demonstrate it by numerical simulation. This technique, borrowed from an analogous scheme of robust population transfer in atomic physics and nuclear magnetic resonance called ‘local optimization’, can keep the intermediate frequency fixed and make the counterintuitive ordering emerge automatically. Here we show an efficient frequency conversion in two-process three wave mixing (TWM). And because the local optimization method is a well-defined, automated computational procedure, we think it would be very useful in the efficient conversion of complicated multi-process TWM, which is a difficult subject in STIRAP.

  3. Microresonator Kerr frequency combs with high conversion efficiency

    CERN Document Server

    Xue, Xiaoxiao; Xuan, Yi; Qi, Minghao; Weiner, Andrew M

    2016-01-01

    Microresonator-based Kerr frequency comb (microcomb) generation can potentially revolutionize a variety of applications ranging from telecommunications to optical frequency synthesis. However, phase-locked microcombs have generally had low conversion efficiency limited to a few percent. Here we report experimental results that achieve ~30% conversion efficiency (~200 mW on-chip comb power excluding the pump) in the fiber telecommunication band with broadband mode-locked dark-pulse combs. We present a general analysis on the efficiency which is applicable to any phase-locked microcomb state. The effective coupling condition for the pump as well as the duty cycle of localized time-domain structures play a key role in determining the conversion efficiency. Our observation of high efficiency comb states is relevant for applications such as optical communications which require high power per comb line.

  4. The Carbon Nanotube Fibers for Optoelectric Conversion and Energy Storage

    OpenAIRE

    Yongfeng Luo; Xi Li; Jianxiong Zhang; Chunrong Liao; Xianjun Li

    2014-01-01

    This review summarizes recent studies on carbon nanotube (CNT) fibers for weavable device of optoelectric conversion and energy storage. The intrinsic properties of individual CNTs make the CNT fibers ideal candidates for optoelectric conversion and energy storage. Many potential applications such as solar cell, supercapacitor, and lithium ion battery have been envisaged. The recent advancement in CNT fibers for optoelectric conversion and energy storage and the current challenge including lo...

  5. Highly efficient frequency conversion with bandwidth compression of quantum light

    CERN Document Server

    Allgaier, Markus; Sansoni, Linda; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2016-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, since elements based on parametric down-conversion sources, quantum dots, color centres or atoms are fundamentally different in their frequencies and bandwidths. While pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here, we demonstrate an engineered sum-frequency-conversion process in Lithium Niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 75.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  6. High efficiency in mode-selective frequency conversion.

    Science.gov (United States)

    Quesada, Nicolás; Sipe, J E

    2016-01-15

    Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this Letter, we argue that these limits can be understood as time-ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore, using a simple scaling argument, we show that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as "attenuators" of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric downconversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode-selective FC.

  7. High efficiency in mode-selective frequency conversion.

    Science.gov (United States)

    Quesada, Nicolás; Sipe, J E

    2016-01-15

    Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this Letter, we argue that these limits can be understood as time-ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore, using a simple scaling argument, we show that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as "attenuators" of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric downconversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode-selective FC. PMID:26766715

  8. Applying a non-parametric efficiency analysis to measure conversion efficiency in Great Britain

    NARCIS (Netherlands)

    Binder, M.; Broekel, T.

    2011-01-01

    In the literature on Sen's capability approach, studies focusing on the empirical measurement of conversion factors are comparatively rare. We add to this field by adopting a measure of 'conversion efficiency' that captures the efficiency with which individuals convert their resources into achieved

  9. Carbon monoxide conversion by anaerobic bioreactor sludges

    NARCIS (Netherlands)

    Sipma, J.; Stams, A.J.M.; Lens, P.N.L.; Lettinga, G.

    2003-01-01

    Seven different anaerobic sludges from wastewater treatment reactors were screened for their ability to convert carbon monoxide (CO) at 30 and 55degreesC
    Seven different anaerobic sludges from wastewater treatment reactors were screened for their ability to convert carbon monoxide (CO) at 30 and

  10. Study on optical characteristics for high efficient wavelength conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Yong Sik; Shin, Hyun Woong [Konkuk University, Seoul (Korea, Republic of)

    2011-07-01

    We developed the optical system for high efficient wavelength-conversion with the basis of high power pulses from the Yb fiber laser at infrared wavelength. To obtain the second harmonics in visible wavelength range, the LBO crystal satisfying critical phase-matching condition would be the best from various possible nonlinear crystals and deliver as high conversion efficiency as 50-60% at maximum. The most obstacle in second harmonic generation for getting high conversion efficiency was demonstrated to the thermal gradient generated by the absorption due to residual impurities in the nonlinear crystal at the fundamental and its harmonic wavelength. One of its resolution was suggested to develop the novel temperature controller to cool in the negative direction to reduce the thermal gradient. To obtain high power pulses at Ultra-violet wavelength by the process of fourth harmonic generation, the CLBO nonlinear crystal satisfying nduce the thermal gradient. condition was also suggested and could deliver as high conversion efficiency as 20% at maximum. Furthermore, we developed the optical system for high efficient wavelength-conversion with the basis of as moderate power as 3 as from a contntuous-wave (cw) Yb fiber laser. Under the pass configuration, the MgO doped crystnonlinear crystal with the length of 30mm was demonstrated to deliver as high power as 15W at its harmonics from a cw Yb fiber laser with power of 40-50 W as the fundamental beam. Finally, we also estimated to develop cw high power ultra-violet beam of 5W from the generated second harmonic beam of 15 W and the high quality CLBO crystal by a fourth harmonic process, reaching a conversion efficiency as high as 30 %.

  11. Efficient broadband third harmonic frequency conversion via angular dispersion

    International Nuclear Information System (INIS)

    In this paper we present experimental measurements and theoretical modeling of third harmonic (3ω) conversion efficiency with optical bandwidth. Third harmonic conversion efficiency drops precipitously as the input bandwidth significantly exceeds the phase matching limitations of the conversion crystals. For Type I/Type II frequency tripling, conversion efficiency be-gins to decrease for bandwidths greater than ∼60 GHz. However, conversion efficiency corresponding to monochromatic phase-matched beams can be recovered provided that the instantaneous Propagation vectors are phase matched at all times. This is achieved by imposing angular spectral dispersion (ASD) on the input beam via a diffraction grating, with a dispersion such that the phase mismatch for each frequency is zero. Experiments were performed on the Optical Sciences Laser (OSL), a 1--100 J class laser at LLNL. These experiments used a 200 GHz bandwidth source produced by a multipassed electro-optic phase modulator. The spectrum produced was composed of discrete frequency components spaced at 3 GHz intervals. Angular dispersion was incorporated by the addition of a 1200 gr/mm diffraction grating oriented at the Littrow angle, and capable of rotation about the beam direction. Experiments were performed with a pulse length of 1-ns and a 1ω input intensity of ∼ 4 GW/cm2 for near optimal dispersion for phase matching, 5.2 μrad/GHz, with 0.1, 60, and 155 GHz bandwidth, as well as for partial dispersion compensation, 1.66 μrad/GHz, with 155 GHz and 0.1 GHz bandwidth. The direction of dispersion was varied incrementally 360 degrees about the beam diameter. The addition of the grating to the beamline reduced the narrowband conversion efficiency by approximately 10%

  12. Applying a nonparametric efficiency analysis to measure conversion efficiency in Great Britain

    OpenAIRE

    Binder, Martin; Broekel, Tom

    2009-01-01

    In the literature on Sen's capability approach, studies focussing on the empirical measurement of conversion factors are comparatively rare. We add to this field by adopting a measure of 'conversion efficiency' that captures the efficiency with which individuals convert their re-sources into achieved functioning. We use a nonparametric efficiency procedure borrowed from production theory and construct such a measure for a set of basic functionings, using data from the wave 2006 of the British...

  13. Efficient fiber coupling of down-conversion photon pairs

    CERN Document Server

    Dragan, A

    2004-01-01

    We develop and apply an effective analytic theory of a non-collinear, broadband type-I parametric down-conversion to study a coupling efficiency of the generated photon pairs into single mode optical fibers. We derive conditions necessary for highly efficient coupling for single and double type-I crystal producing polarization entangled states of light. We compare the obtained approximate analytic expressions with the exact numerical solutions and discuss the results for a case of BBO crystals.

  14. Catalysts for Efficient Production of Carbon Nanotubes

    Science.gov (United States)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  15. Solar power conversion efficiency in modulated silicon nanowire photonic crystals

    Science.gov (United States)

    Deinega, Alexei; John, Sajeev

    2012-10-01

    It is suggested that using only 1 μm of silicon, sculpted in the form of a modulated nanowire photonic crystal, solar power conversion efficiency in the range of 15%-20% can be achieved. Choosing a specific modulation profile provides antireflection, light trapping, and back-reflection over broad angles in targeted spectral regions for high efficiency power conversion without solar tracking. Solving both Maxwell's equations in the 3D photonic crystal and the semiconductor drift-diffusion equations in each nanowire, we identify optimal junction and contact geometries and study the influence of the nanowire surface curvature on solar cell efficiency. We demonstrate that suitably modulated nanowires enable 20% efficiency improvement over their straight counterparts made of an equivalent amount of silicon. We also discuss the efficiency of a tandem amorphous and crystalline silicon nanowire photonic crystal solar cell. Opportunities for "hot carrier" collection and up-conversion of infrared light, enhanced by photonic crystal geometry, facilitate further improvements in power efficiency.

  16. Phosphoketolase Pathway Engineering for Carbon-Efficient Biocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Henard, Calvin Andrew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Freed, Emily Frances [National Renewable Energy Lab. (NREL), Golden, CO (United States); Guarnieri, Michael Thomas [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-09-08

    Recent advances in metabolic engineering have facilitated the development of microbial biocatalysts capable of producing an array of bio-products, ranging from fuels to drug molecules. These bio-products are commonly generated through an acetyl-CoA intermediate, which serves as a key precursor in the biological conversion of carbon substrates. Moreover, conventional biocatalytic upgrading strategies proceeding through this route are limited by low carbon efficiencies, in large part due to carbon losses associated with pyruvate decarboxylation to acetyl-CoA. Bypass of pyruvate decarboxylation offers a means to dramatically enhance carbon yields and, in turn, bioprocess economics. Here, we discuss recent advances and prospects for employing the phosphoketolase pathway for direct biosynthesis of acetyl-CoA from carbon substrates, and phosphoketolase-based metabolic engineering strategies for carbon efficient biocatalysis.

  17. Carbon fuel particles used in direct carbon conversion fuel cells

    Science.gov (United States)

    Cooper, John F.; Cherepy, Nerine

    2012-10-09

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  18. CONVERSION EFFICIENCY IMPROVEMENT FOR ENERGY CONSERVATION USING MATRIX CONVERTER

    Directory of Open Access Journals (Sweden)

    G.N. SURYA

    2012-04-01

    Full Text Available Efficient conversion of electrical energy from one form to another has always been a fascinating domain for researchers. Right from the era of mercury arc rectifiers to present AC-DC-AC two stage converters and cycloconverters, efforts are consistently being laid to minimize the losses involved in conversion process. In the present study the AC-AC conversion topology known as Matrix Converter (MC, is modeled using MATLAB. Venturini’s simplified algorithm is used to determine the switch modulation duty cycle. The model is designedfor conversion of 50 Hz input frequency to 100 Hz and 25 Hz, using a simplified switch modulation strategy. The waveforms generated by MATLAB/simulink confirm the reduction of conversion losses by 12% to 15% with use of proposed model as compared to conventional (PWM converters. It is not intended in this study just to list out various works done so for but to establish the brevity of fundamental concept representing the simplified design along with its application areas mainly the VFDs and Wind Energy Conversion Systems (WECS. The model has also been tested for control of induction motor with 100 HZ and 25 Hz output frequencies. The waveforms of changed frequencies and reduced losses confirm the results anticipated at design stage.

  19. Photoelectric Conversion Efficiency Enhanced by Tilting Monocrystalline Silicon Photovoltaic Devices

    Institute of Scientific and Technical Information of China (English)

    LI Jian-ming; CHONG Ming; XU Jia-dong; HU Chuan-xian; DUAN Xiao-feng; GAO Min; WANG Feng-lian

    2004-01-01

    Based on the idea of tilting a photoelectric conversion device,the monocrystalline silicon p-n junction device was tilted to make light incident upon the device at an angle of 45° with the normal of the device surface,resulting in infrared multiple-internal-reflection inside the device.The internal reflection leads to path length increase of infrared light,making the enhancement of infrared absorption of the device.An increase of 11% in energy conversion efficiency has been obtained through tilting the device.

  20. Novel phase of carbon, ferromagnetism, and conversion into diamond

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh [Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)

    2015-12-07

    We report the discovery of a new phase of carbon (referred to as Q-carbon) and address fundamental issues related to direct conversion of carbon into diamond at ambient temperatures and pressures in air without any need for catalyst and presence of hydrogen. The Q-carbon is formed as result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram (P vs. T) of carbon and show that by rapid quenching kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. It is shown that nanosecond laser heating of diamond-like amorphous carbon on sapphire, glass, and polymer substrates can be confined to melt carbon in a super undercooled state. By quenching the carbon from the super undercooled state, we have created a new state of carbon (Q-carbon) from which nanodiamond, microdiamond, microneedles, and single-crystal thin films are formed depending upon the nucleation and growth times allowed for diamond formation. The Q-carbon quenched from liquid is a new state of solid carbon with a higher mass density than amorphous carbon and a mixture of mostly fourfold sp{sup 3} (75%–85%) with the rest being threefold sp{sup 2} bonded carbon (with distinct entropy). It is expected to have new and improved mechanical hardness, electrical conductivity, chemical, and physical properties, including room-temperature ferromagnetism (RTFM) and enhanced field emission. Here we present interesting results on RTFM, enhanced electrical conductivity and surface potential of Q-carbon to emphasize its unique properties. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g{sup −1}. From the Q-carbon, diamond phase is nucleated and a variety of micro- and nanostructures and large-area single-crystal diamond sheets are grown by allowing

  1. Novel phase of carbon, ferromagnetism, and conversion into diamond

    Science.gov (United States)

    Narayan, Jagdish; Bhaumik, Anagh

    2015-12-01

    We report the discovery of a new phase of carbon (referred to as Q-carbon) and address fundamental issues related to direct conversion of carbon into diamond at ambient temperatures and pressures in air without any need for catalyst and presence of hydrogen. The Q-carbon is formed as result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram (P vs. T) of carbon and show that by rapid quenching kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. It is shown that nanosecond laser heating of diamond-like amorphous carbon on sapphire, glass, and polymer substrates can be confined to melt carbon in a super undercooled state. By quenching the carbon from the super undercooled state, we have created a new state of carbon (Q-carbon) from which nanodiamond, microdiamond, microneedles, and single-crystal thin films are formed depending upon the nucleation and growth times allowed for diamond formation. The Q-carbon quenched from liquid is a new state of solid carbon with a higher mass density than amorphous carbon and a mixture of mostly fourfold sp3 (75%-85%) with the rest being threefold sp2 bonded carbon (with distinct entropy). It is expected to have new and improved mechanical hardness, electrical conductivity, chemical, and physical properties, including room-temperature ferromagnetism (RTFM) and enhanced field emission. Here we present interesting results on RTFM, enhanced electrical conductivity and surface potential of Q-carbon to emphasize its unique properties. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. From the Q-carbon, diamond phase is nucleated and a variety of micro- and nanostructures and large-area single-crystal diamond sheets are grown by allowing growth times as needed

  2. Platinum nanoparticle decorated silicon nanowires for efficient solar energy conversion.

    Science.gov (United States)

    Peng, Kui-Qing; Wang, Xin; Wu, Xiao-Ling; Lee, Shuit-Tong

    2009-11-01

    High-density aligned n-type silicon nanowire (SiNW) arrays decorated with discrete 5-10 nm platinum nanoparticles (PtNPs) have been fabricated by aqueous electroless Si etching followed by an electroless platinum deposition process. Coating of PtNPs on SiNW sidewalls yielded a substantial enhancement in photoconversion efficiency and an apparent energy conversion efficiency of up to 8.14% for the PtNP-decorated SiNW-based photoelectrochemical solar cell using a liquid electrolyte containing Br(-)/Br(2) redox couple. The results demonstrate PtNP-decorated SiNWs to be a promising hybrid system for solar energy conversion. PMID:19807069

  3. Photocurrent generation efficiency of a carbon nanotube pn junction

    Science.gov (United States)

    McCulley, Daniel; Aspitarte, Lee; Minot, Ethan

    Carrier multiplication effects can enhance the quantum efficiency of photovoltaic devices. For example, quantum dot solar cells have demonstrated photon-to-electron conversion efficiencies greater than 100% when photon energies exceed twice the band gap. Carbon nanotube photodiodes exhibit carrier multiplication effects (Gabor et al., Science 2009), but the quantum efficiency of such photodiodes has not previously been characterized. We have reproduced the carrier multiplication phenomena in individual CNT pn junctions and investigated the conditions under which it occurs. We will present early results quantifying the internal quantum efficiency of the process.

  4. An Efficient Automated English to Bengali Script Conversion Mechanism

    OpenAIRE

    Enakshi Mukhopadhyay; Priyanka Mazumder; Saberi Goswami; Romit S Beed

    2014-01-01

    The authors aim at developing an efficient, unequivocal and automated method of generating Bengali language using English alphabets and simple English punctuation notes. Such art of writing Bengali language using English scripts shall be of immense help for those Bengali-speaking persons who cannot write in Bengali, yet can speak well and would require written communication in Bengali for official and personal conversation. Currently, Bengali keyboards are not available in the market, and acc...

  5. Saturation and energy-conversion efficiency of auroral kilometric radiation

    Science.gov (United States)

    Wu, C. S.; Tsai, S. T.; Xu, M. J.; Shen, J. W.

    1981-01-01

    A quasi-linear theory is used to study the saturation level of the auroral kilometric radiation. The investigation is based on the assumption that the emission is due to a cyclotron maser instability as suggested by Wu and Lee and Lee et al. The thermodynamic bound on the radiation energy is also estimated separately. The energy-conversion efficiency of the radiation process is discussed. The results are consistent with observations.

  6. Conversion of far ultraviolet to visible radiation: absolute measurements of the conversion efficiency of tetraphenyl butadiene

    Science.gov (United States)

    Vest, Robert E.; Coplan, Michael A.; Clark, Charles W.

    Far ultraviolet (FUV) scintillation of noble gases is used in dark matter and neutrino research and in neutron detection. Upon collisional excitation, noble gas atoms recombine into excimer molecules that decay by FUV emission. Direct detection of FUV is difficult. Another approach is to convert it to visible light using a wavelength-shifting medium. One such medium, tetraphenyl butadiene (TPB) can be vapor-deposited on substrates. Thus the quality of thin TPB films can be tightly controlled. We have measured the absolute efficiency of FUV-to-visible conversion by 1 μm-thick TPB films vs. FUV wavelengths between 130 and 300 nm, with 1 nm resolution. The energy efficiency of FUV to visible conversion varies between 1% and 5%. We make comparisons with other recent results. Work performed at the NIST SURF III Synchrotron Ultraviolet Radiation Facility,.

  7. Photon energy conversion efficiency in gamma-ray spectrometry.

    Science.gov (United States)

    Švec, Anton

    2016-01-01

    Photon energy conversion efficiency coefficient is presented as the ratio of total energy registered in the collected spectrum to the emitted photon energy. This parameter is calculated from the conventional gamma-ray histogram and in principle is not affected by coincidence phenomena. This feature makes it particularly useful for calibration and measurement of radionuclide samples at close geometries. It complements the number of efficiency parameters used in gamma-ray spectrometry and can partly change the view as to how the gamma-ray spectra are displayed and processed.

  8. Efficiency of feed nitrogen conversion in dairy cattle herds

    Directory of Open Access Journals (Sweden)

    Carla Lazzaroni

    2010-01-01

    Full Text Available To evaluate the effect of feasible strategies to mitigate dairy herd’s environmental impact in a homogeneous area, the actual level of N excretion and conversion efficiency was determined in fifteen farms located in the North-West of Italy. Main factors affecting N efficiency (feeds consumption and composition, live weight, productions, milk urea and reproductive indexes were recorded for cows (C, heifers (H, 12-24 months and young heifers (YH, 6-12 months. N requirements, retention, excretion and efficiency were calculated. N excretion was respectively 131.39, 60.88 and 47.49 kg/year/head for C, H and YH and 14.07 kg/year per litre of milk in C. Feed N conversion efficiency was respectively 28.40, 8.90 and 6.64 in C, H and YH. In the studied farms N efficiency could be increased acting on the most important factors affecting N utilisation, so reducing the environmental impact of dairy cattle.

  9. Efficient and broadband polarization conversion with the coupled metasurfaces.

    Science.gov (United States)

    Huang, Cheng-ping

    2015-12-14

    Coupled metasurfaces may refer to a composite plasmonic structure, which consists of multilayered but usually different metasurfaces. A pair of orthogonal plasmonic polarizers, which represents one of such systems, can induce a transmission of light and 90-degree polarization rotation. We explored the effect systematically and found that such effect may be highly efficient and broadband in the near-infrared region. By combining the low-loss metal (silver), the longer operating wavelength, and a work style using propagating waveguide mode, conversion efficiency more than 80% has been suggested near the telecom wavelength. We also suggested that, by overlapping the internal surface-plasmon (2, 0) and (1, 1) modes, an efficient and wideband polarization rotation can be realized. The maximal efficiency is 83% around the wavelength 1340 nm, and the working bandwidth reaches 300 nm. Similar effect has also been revealed in the THz band. The results are useful for constructing compact and high-performance polarization rotators. PMID:26698992

  10. Conversion of lignin precursors to carbon fibers with nanoscale graphitic domains

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sabornie [ORNL; Jones, Eric B [ORNL; Clingenpeel, Amy [National High Magnetic Field Laboratory (Magnet Lab), Florida; McKenna, Amy [National High Magnetic Field Laboratory (Magnet Lab), Florida; Rios, Orlando [ORNL; McNutt, Nicholas W [ORNL; Keffer, David J. [University of Tennessee, Knoxville (UTK); Johs, Alexander [ORNL

    2014-08-04

    Lignin is one of the most abundant and inexpensive natural biopolymers. It can be efficiently converted to low cost carbon fiber, monolithic structures or powders that could be used directly in the production of anodes for lithium-ion batteries. In this work, we report processing parameters relevant for the conversion of lignin precursors into electrochemically active carbon fibers, the impact of lignin precursor modification on melt processing and the microstructure of the final carbon material. The conversion process encompasses melt spinning of the lignin precursor, oxidative stabilization and a low temperature carbonization step in a nitrogen/hydrogen atmosphere. To assess electrochemical performance, we determined resistivities of individual carbon fiber samples and characterized the microstructure by scanning electron microscopy and neutron diffraction. The chemical modification and subsequent thermomechanical processing methods reported here are effective for conversion into carbon fibers while preserving the macromolecular backbone structure of lignin. Modification of softwood lignin produced functionalities and rheological properties that more closely resemble hardwood lignin thereby enabling the melt processing of softwood lignin in oxidative atmospheres (air). Structural characterization of the carbonized fibers reveals nanoscale graphitic domains that are linked to enhanced electrochemical performance.

  11. Energy Efficiency Policy and Carbon Pricing

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The main message of this paper is that while carbon pricing is a prerequisite for least-cost carbon mitigation strategies, carbon pricing is not enough to overcome all the barriers to cost-effective energy efficiency actions. Energy efficiency policy should be designed carefully for each sector to ensure optimal outcomes for a combination of economic, social and climate change goals. This paper aims to examine the justification for specific energy efficiency policies in economies with carbon pricing in place. The paper begins with an inventory of existing market failures that attempt to explain the limited uptake of energy efficiency. These market failures are investigated to see which can be overcome by carbon pricing in two subsectors -- electricity use in residential appliances and heating energy use in buildings. This analysis finds that carbon pricing addresses energy efficiency market failures such as externalities and imperfect energy markets. However, several market and behavioural failures in the two subsectors are identified that appear not to be addressed by carbon pricing. These include: imperfect information; principal-agent problems; and behavioural failures. In this analysis, the policies that address these market failures are identified as complementary to carbon pricing and their level of interaction with carbon pricing policies is relatively positive. These policies should be implemented when they can improve energy efficiency effectively and efficiently (and achieve other national goals such as improving socio-economic efficiency).

  12. Hierarchically structured carbon nanotubes for energy conversion and storage

    Science.gov (United States)

    Du, Feng

    As the world population continues to increase, large amounts of energy are consumed. Reality pushes us to find new energy or use our current energy more efficiently. Researches on energy conversion and storage have become increasingly important and essential. This grand challenge research has led to a recent focus on nanostructured materials. Carbon nanomaterials such as carbon nanotubes (CNTs) play a critical role in all of these nanotechnology challenges. CNTs have a very large surface area, a high electrochemical accessibility, high electronic conductivity and strong mechanical properties. This combination of properties makes them promising materials for energy device applications, such as FETs, supercapacitors, fuel cells, and lithium batteries. This study focuses on exploring the possibility of using vertically aligned carbon nanotubes (VA-CNTs) as the electrode materials in these energy applications. For the application of electrode materials, electrical conductive, vertically aligned CNTs with controllable length and diameter were synthesized. Several CVD methods for VA-CNT growth have been explored, although the iron / aluminum pre-coated catalyst CVD system was the main focus. A systematic study of several factors, including growth time, temperature, gas ratio, catalyst coating was conducted. The mechanism of VA-CNTs was discussed and a model for VA-CNT length / time was proposed to explain the CNT growth rate. Furthermore, the preferential growth of semiconducting (up to 96 atom% carbon) VA-SWNTs by using a plasma enhanced CVD process combined with fast heating was also explored, and these semiconducting materials have been directly used for making FETs using simple dispersion in organic solvent, without any separation and purification. Also, by inserting electron-accepting nitrogen atoms into the conjugated VA-CNT structure during the growth process, we synthesized vertically aligned nitrogen containing carbon nanotubes (VA-NCNTs). After purification of

  13. Half-Heusler Alloys for Efficient Thermoelectric Power Conversion

    Science.gov (United States)

    Chen, Long; Zeng, Xiaoyu; Tritt, Terry M.; Poon, S. Joseph

    2016-07-01

    Half-Heusler (HH) phases (space group F43m, Clb) are increasingly gaining attention as promising thermoelectric materials in view of their thermal stability and environmental benignity as well as efficient power output. Until recently, the verifiable dimensionless figure of merit (ZT) of HH phases has remained moderate near 1, which limits the power conversion efficiency of these materials. We report herein ZT ˜ 1.3 in n-type (Hf,Zr)NiSn alloys near 850 K developed through elemental substitution and simultaneous embedment of nanoparticles in the HH matrix, obtained by annealing the samples close to their melting temperatures. Introduction of mass fluctuation and scattering centers play a key role in the high ZT measured, as shown by the reduction of thermal conductivity and increase of thermopower. Based on computation, the power conversion efficiency of a n-p couple module based on the new n-type (Hf,Zr,Ti)NiSn particles-in-matrix composite and recently reported high-ZT p-type HH phases is expected to reach 13%, comparable to that of state-of-the-art materials, but with the mentioned additional materials and environmental attributes. Since the high efficiency is obtained without tuning the microstructure of the HH phases, it leaves room for further optimization.

  14. GaN transistors for efficient power conversion

    CERN Document Server

    Lidow, Alex; de Rooij, Michael; Reusch, David

    2014-01-01

    The first edition of GaN Transistors for Efficient Power Conversion was self-published by EPC in 2012, and is currently the only other book to discuss GaN transistor technology and specific applications for the technology. More than 1,200 copies of the first edition have been sold through Amazon or distributed to selected university professors, students and potential customers, and a simplified Chinese translation is also available. The second edition has expanded emphasis on applications for GaN transistors and design considerations. This textbook provides technical and application-focused i

  15. Investigating the Optimum Efficiency of Acoustoelectric Conversion Plate Devices

    Directory of Open Access Journals (Sweden)

    Chien-Chih Chen

    2014-04-01

    Full Text Available This study aims to develop the acoustoelectric conversion plate in terms of electromagnetic induction law to convert sound energy to electricity, where the developed apparatus is made of three parts, the thin film coil, the spring, and the high-intensity magnetic framework. In process, the thin film coil receives the injecting sound vibration in connection with the spring to cause the reciprocating motion between the coil and the high-intensity magnet, which yields the electromotive force (EMF. In this study, a pearl plate of length 95 mm, width 95 mm, and thickness 1.5 mm adhered with a PET film of thickness 0.08mm is built as the substrate plate due to it has good properties of light and elasticity. In connection with the substrate plate and the electric coil is the thin film coil. Experiments used the speaker with output frequencies of 30~156 Hz and sound power of 0.5 W (sound intensity 0.32 W/m2, sound pressure level 115 dB as the sound source. The sound energy is captured by the acoustoelectric conversion plate for working efficiency and optimization parameters analysis. The studied parameters content of diameter, turns, and width of electric coil as well as distance between high intensity magnet and coil. The results show that diameter 0.11 mm, turns 220, and width 3 mm of the electric coil, in connection with steel spring of diameter 0.2 mm while input sound is 30 Hz, receives the average output voltage of 0.57 V, the average output current of 5.46 mA, the average output power of 3.13 mW, and the sound electric conversion efficiency of 0.63%. This innovation device could be used in highway, near waterfalls, and some high noise factories to capture energy for immediately charging cell-phone to save human life.

  16. Polymer heterostructures with embedded carbon nanotubes for efficient photovoltaic cells

    International Nuclear Information System (INIS)

    Polymer photovoltaic cells (PVC) are intensely investigated because of their potential advantages over Si-based PVCs. Their present drawbacks are low conversion efficiency, limited exciton diffusion length, poor hole carriers transport and short lifetime. The highest conversion efficiency achieved so far in spin-coated polymer blends is close to 5%. Recently, efficiency growing has been demonstrated in multilayer architectures involving a donor/acceptor bulk heterojunction. Alternatively, a nanomaterial has been added to the polymer active layer to facilitate excitons dissociation and carriers transport through the polymer matrix. In this work we investigate both these approaches, first embedding single wall Carbon Nanotubes (SWCNT) in the polymeric matrix to improve the electrical transport and second studying the optical absorption of different polymer thin films to optimize the spectral response of the donor/acceptor heterojunction.

  17. Combination of carbon nitride and carbon nanotubes: synergistic catalysts for energy conversion.

    Science.gov (United States)

    Gong, Yutong; Wang, Jing; Wei, Zhongzhe; Zhang, Pengfei; Li, Haoran; Wang, Yong

    2014-08-01

    Due to their versatile features and environmental friendliness, functionalized carbon materials show great potential in practical applications, especially in energy conversion. Developing carbon composites with properties that can be modulated by simply changing the ratio of the original materials is an intriguing synthetic strategy. Here, we took cyanamide and multiwalled carbon nanotubes as precursors and introduced a facile method to fabricate a series of graphitic carbon nitride/carbon nanotubes (g-C3 N4 /CNTs) composites. These composites demonstrated different practical applications with different weight ratios of the components, that is, they showed synergistic effects in optoelectronic conversion when g-C3 N4 was the main ingredient and in oxygen reduction reaction (ORR) when CNTs dominated the composites. Our experiments indicated that the high electrical conductivity of carbon nanotubes promoted the transmission of the charges in both cases.

  18. A TEG Efficiency Booster with Buck-Boost Conversion

    Science.gov (United States)

    Wu, Hongfei; Sun, Kai; Zhang, Junjun; Xing, Yan

    2013-07-01

    A thermoelectric generator (TEG) efficiency booster with buck-boost conversion and power management is proposed as a TEG battery power conditioner suitable for a wide TEG output voltage range. An inverse-coupled inductor is employed in the buck-boost converter, which is used to achieve smooth current with low ripple on both the TEG and battery sides. Furthermore, benefiting from the magnetic flux counteraction of the two windings on the coupled inductor, the core size and power losses of the filter inductor are reduced, which can achieve both high efficiency and high power density. A power management strategy is proposed for this power conditioning system, which involves maximum power point tracking (MPPT), battery voltage control, and battery current control. A control method is employed to ensure smooth switching among different working modes. A modified MPPT control algorithm with improved dynamic and steady-state characteristics is presented and applied to the TEG battery power conditioning system to maximize energy harvesting. A 500-W prototype has been built, and experimental tests carried out on it. The power efficiency of the prototype at full load is higher than 96%, and peak efficiency of 99% is attained.

  19. Efficient computerized model for dynamic analysis of energy conversion systems

    Science.gov (United States)

    Hughes, R. D.; Lansing, F. L.; Khan, I. R.

    1983-02-01

    In searching for the optimum parameters that minimize the total life cycle cost of an energy conversion system, various combinations of components are examined and the resulting system performance and associated economics are studied. The systems performance and economics simulation computer program (SPECS) was developed to fill this need. The program simulates the fluid flow, thermal, and electrical characteristics of a system of components on a quasi-steady state basis for a variety of energy conversion systems. A unique approach is used in which the set of characteristic equations is solved by the Newton-Raphson technique. This approach eliminates the tedious iterative loops which are found in comparable programs such as TRNSYS or SOLTES-1. Several efficient features were also incorporated such as the centralized control and energy management scheme, and analogous treatment of energy flow in electrical and mechanical components, and the modeling of components of similar fundamental characteristics using generic subroutines. Initial tests indicate that this model can be used effectively with a relatively small number of time steps and low computer cost.

  20. Multi-Kilovolt X-Ray Conversion Efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Back, C A; Davis, J L; Grun, J; Landen, O L; Miller, M C; Suter, L J

    2001-08-23

    X-ray sources in the 3-7 keV energy regime can be produced by laser-irradiating mid- and high-Z gas-filled targets with high-powered lasers. A series of experiments have been performed using underdense targets that are supersonically heated with {approx} 35 kJ of 0.35 {micro}m laser light. These targets were cylindrical Be enclosures that were filled with 1-2 atms of Xe or Ar gas. L-shell x-ray emission is emitted from the plasma and detected by Bragg crystal spectrometers and x-ray diodes. Absolute flux measurements show conversion efficiencies of {approx} 10% in the multi-kilovolt x-ray emission. These sources can be used as bright x-ray backlighters or for material testing.

  1. Effect of Conversion Efficiency on Gamma-Ray Burst Energy

    Institute of Scientific and Technical Information of China (English)

    Lei Xu; Zi-Gao Dai

    2004-01-01

    Beaming effect makes it possible that gamma-ray bursts have a standard energy,but the gamma-ray energy release is sensitive to some parameters.Our attention is focused on the effect of the gamma ray conversion efficiency(ηγ),which may range between 0.01 and 0.9,and which probably has a random value for different GRBs under certain conditions.Making use of the afterglow data from the literature,we carried out a complete correction to the conical opening angle formula.Within the framework of the conical jet model,we ran a simple Monte Carlo simulation for random values of ηγ,and found that the gamma-ray energy release is narrowly clustered,whether we use a constant value of ηγ or random values for different gamma-ray bursts.

  2. Tandem photovoltaic solar cells and increased solar energy conversion efficiency

    Science.gov (United States)

    Loferski, J. J.

    1976-01-01

    Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

  3. Carbon emissions from forest conversion by Kalimantan oil palm plantations

    Science.gov (United States)

    Carlson, Kimberly M.; Curran, Lisa M.; Asner, Gregory P.; Pittman, Alice Mcdonald; Trigg, Simon N.; Marion Adeney, J.

    2013-03-01

    Oil palm supplies >30% of world vegetable oil production. Plantation expansion is occurring throughout the tropics, predominantly in Indonesia, where forests with heterogeneous carbon stocks undergo high conversion rates. Quantifying oil palm's contribution to global carbon budgets therefore requires refined spatio-temporal assessments of land cover converted to plantations. Here, we report oil palm development across Kalimantan (538,346km2) from 1990 to 2010, and project expansion to 2020 within government-allocated leases. Using Landsat satellite analyses to discern multiple land covers, coupled with above- and below-ground carbon accounting, we develop the first high-resolution carbon flux estimates from Kalimantan plantations. From 1990 to 2010, 90% of lands converted to oil palm were forested (47% intact, 22% logged, 21% agroforests). By 2010, 87% of total oil palm area (31,640km2) occurred on mineral soils, and these plantations contributed 61-73% of 1990-2010 net oil palm emissions (0.020-0.024GtCyr-1). Although oil palm expanded 278% from 2000 to 2010, 79% of allocated leases remained undeveloped. By 2020, full lease development would convert 93,844km2 (~ 90% forested lands, including 41% intact forests). Oil palm would then occupy 34% of lowlands outside protected areas. Plantation expansion in Kalimantan alone is projected to contribute 18-22% (0.12-0.15GtCyr-1) of Indonesia's 2020 CO2-equivalent emissions. Allocated oil palm leases represent a critical yet undocumented source of deforestation and carbon emissions.

  4. Catalytic activity of carbon nanotubes in the conversion of aliphatic alcohols

    Science.gov (United States)

    Zhitnev, Yu. N.; Tveritinova, E. A.; Chernyak, S. A.; Savilov, S. V.; Lunin, V. V.

    2016-06-01

    Carbon nanotubes (CNTs) obtained via the catalytic pyrolysis of hexane at 750°C were studied as the catalysts in conversion of C2-C4 alcohols. The efficiency of CNTs as catalysts in dehydration and dehydrogenation of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol was studied by means of pulse microcatalysis. The surface and structural characteristics of CNTs are investigated via SEM, TEM, DTA, BET, and XPS. CNTs are shown to be effective catalysts in the conversion of alcohols and do not require additional oxidative treatment. The regularities of the conversion of aliphatic alcohols, related to the properties of the CNTs surface and the structure of the alcohols are identified.

  5. Conversion of carbon dioxide to valuable petrochemicals:An approach to clean development mechanism

    Institute of Scientific and Technical Information of China (English)

    Farnaz Tahriri Zangeneh; Saeed Sahebdelfar; Maryam Takht Ravanchi

    2011-01-01

    The increase of atmospheric carbon dioxide and the global warming due to its greenhouse effect resulted in worldwide concerns. On the other hand, carbon dioxide might be considered as a valuable and renewable carbon source. One approach to reduce carbon dioxide emissions could be its capture and recycle via transformation into chemicals using the technologies in C1 chemistry. Despite its great interest, there are difficulties in CO2 separation on the one hand, and thermodynamic stability of carbon dioxide molecule rendering its chemical activity low on the other hand. Carbon dioxide has been already used in petrochemical industries for production of limited chemicals such as urea.The utilization of carbon dioxide does not necessarily involve development of new processes, and in certain processes such as methanol synthesis and methane steam reforming, addition of CO2 into the feed results in its utilization and increases carbon efficiency. In other cases,modifications in catalyst and/or processes, or even new catalysts and processes, are necessary. In either case, catalysis plays a crucial role in carbon dioxide conversion and effective catalysts are required for commercial realization of the related processes. Technologies for CO2 utilization are emerging after many years of research and development efforts.

  6. Overall energy conversion efficiency of a photosynthetic vesicle.

    Science.gov (United States)

    Sener, Melih; Strumpfer, Johan; Singharoy, Abhishek; Hunter, C Neil; Schulten, Klaus

    2016-08-26

    The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides, we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytb⁢c1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules acts in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%-5% of full sunlight is calculated to be 0.12-0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination.

  7. Feed Conversion Efficiency in Japanese Quail Egg Production Mathematical Assisted

    Directory of Open Access Journals (Sweden)

    Monica Pârvu

    2010-05-01

    Full Text Available It was study the feed conversion efficiency in Japanese quail using energy and protein balances during the peak period of laying. The quails were given a diet with 20% crude protein and 2880 ME kcal/kg feed. The feed was given ad libitum. The environmental temperature was 250C (neutral thermal zone. The energy and protein balances were studied for three weeks. It was monitored the fallowing parameters: feed intake, excreted waste, body weight evolution, egg production. Feed, excreta and samples of egg and meat were analyzed according to Weende scheme. On the basis of digestibility and comparative slaughtering, were determined the energy and protein requirements for maintenance and for protein and fat retention mathematical assisted. The daily feed intake was 361 KJ gross energy and 5.32 g crude protein. The energy and protein requirements for maintenance were 648 KJ/kg0.75 and 6.2 g/ kg0.75. The efficiency of metabolisable energy utilisation on egg production was 26.6% and for corporal synthesis 5.5%. The obtained results will be used to develop a mathematical model for energy and protein retention in Japanese laying quail.

  8. Overall energy conversion efficiency of a photosynthetic vesicle

    Science.gov (United States)

    Sener, Melih; Strumpfer, Johan; Singharoy, Abhishek; Hunter, C Neil; Schulten, Klaus

    2016-01-01

    The chromatophore of purple bacteria is an intracellular spherical vesicle that exists in numerous copies in the cell and that efficiently converts sunlight into ATP synthesis, operating typically under low light conditions. Building on an atomic-level structural model of a low-light-adapted chromatophore vesicle from Rhodobacter sphaeroides, we investigate the cooperation between more than a hundred protein complexes in the vesicle. The steady-state ATP production rate as a function of incident light intensity is determined after identifying quinol turnover at the cytochrome bc1 complex (cytb⁢c1) as rate limiting and assuming that the quinone/quinol pool of about 900 molecules acts in a quasi-stationary state. For an illumination condition equivalent to 1% of full sunlight, the vesicle exhibits an ATP production rate of 82 ATP molecules/s. The energy conversion efficiency of ATP synthesis at illuminations corresponding to 1%–5% of full sunlight is calculated to be 0.12–0.04, respectively. The vesicle stoichiometry, evolutionarily adapted to the low light intensities in the habitat of purple bacteria, is suboptimal for steady-state ATP turnover for the benefit of protection against over-illumination. DOI: http://dx.doi.org/10.7554/eLife.09541.001 PMID:27564854

  9. A Study on the RF-DC Conversion Efficiency of Microstrip Patch Rectenna

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yang Ha; Youn, Dong Gi; Kim, Kwan Ho [Korea Electrotechnology Research Institute (Korea); Rhee, Young Chul [Kyungnam University (Korea)

    2000-07-01

    We designed and manufactured microstrip patch antenna mainly used in the rectenna and then analysed RF-DC conversion efficiency of wireless power transmission system. We analyse conversion efficiency of load, direction of linear and dual polization rectenna. We found that the maximum efficiency would be about 70% of load and direction in patch type. In conclusion, we found that total conversion efficiency is 64% - 71% in patch Rectenna. (author). 5 refs., 8 figs., 1 tab.

  10. Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic.

    Science.gov (United States)

    Kauffman, J Boone; Heider, Chris; Norfolk, Jennifer; Payton, Frederick

    2014-04-01

    Mangroves are recognized to possess a variety of ecosystem services including high rates of carbon sequestration and storage. Deforestation and conversion of these ecosystems continue to be high and have been predicted to result in significant carbon emissions to the atmosphere. Yet few studies have quantified the carbon stocks or losses associated with conversion of these ecosystems. In this study we quantified the ecosystem carbon stocks of three common mangrove types of the Caribbean as well as those of abandoned shrimp ponds in areas formerly occupied by mangrove-a common land-use conversion of mangroves throughout the world. In the mangroves of the Montecristi Province in Northwest Dominican Republic we found C stocks ranged from 706 to 1131 Mg/ha. The medium-statured mangroves (3-10 m in height) had the highest C stocks while the tall (> 10 m) mangroves had the lowest ecosystem carbon storage. Carbon stocks of the low mangrove (shrub) type (carbon-rich soils as deep as 2 m. Carbon stocks of abandoned shrimp ponds were 95 Mg/ha or approximately 11% that of the mangroves. Using a stock-change approach, the potential emissions from the conversion of mangroves to shrimp ponds ranged from 2244 to 3799 Mg CO2e/ha (CO2 equivalents). This is among the largest measured C emissions from land use in the tropics. The 6260 ha of mangroves and converted mangroves in the Montecristi Province are estimated to contain 3,841,490 Mg of C. Mangroves represented 76% of this area but currently store 97% of the carbon in this coastal wetland (3,696,722 Mg C). Converted lands store only 4% of the total ecosystem C (144,778 Mg C) while they comprised 24% of the area. By these metrics the replacement of mangroves with shrimp and salt ponds has resulted in estimated emissions from this region totaling 3.8 million Mg CO2e or approximately 21% of the total C prior to conversion. Given the high C stocks of mangroves, the high emissions from their conversion, and the other important

  11. A theoretical analysis of optical-to-THz conversion efficiency via optical rectification

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A theoretical analysis of an ultra-short pulse converted to Terahertz radiation via optical rectification in nonlinear optical crystal is presented here;several factors that affect optical-to-THz conversion efficiencies are discussed;pulse durations affect the conversion efficiency effectively:when crystal length is equal to the optimal crystal length lc,optical-to-THz conversion efficiency is the highest,but for the periodically-inverted electro-optic crystals,conversion efficiency is almost proportional to the crystal length when absorption can be neglected.Taking account of the absorption of crystals,effective length of crystal is Leff=0.63/α,there is no apparent increase of conversion efficiency and the conversion efficiency approaches to a constant eventually when the crystal length is increased.

  12. Efficient energy conversion in the pulp and paper industry

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, F.; Perin-Levasseur, Z.

    2005-07-01

    This yearly report for the Swiss Federal Office of Energy (SFOE) takes a look at the work done in 2005 and the work planned for 2006 within the framework of the Efficient Energy Conversion in the Pulp and Paper Industry project. The results of investigations made at a large pulp and paper facility in Switzerland are presented and analysed. Data models of the steam and condensate networks and of the processes involved are examined. An additional model of the sulphur loop has been also elaborated. From this analysis, a list of required measurements has been developed. Several performance indicators have also been calculated: A systematic analysis method developed to identify sections where condensate could be recovered is discussed. A systematic definition of the hot and cold streams in the process is being developed in order to compute the minimum energy requirements of the process. Evaluating this minimum energy requirement from the data available is to be used to prepare definitions of the energy savings possible.

  13. Low cost and efficient photovoltaic conversion by nanocrystalline solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Graetzel, M. [Institut de Chimie Physique, Ecole Polytechnique Federal de Lausanne (Switzerland)

    1996-09-01

    Solar cells are expected to provide environmentally friendly solutions to the world`s energy supply problem. Learning from the concepts used by green plants we have developed a molecular photovoltaic device whose overall efficiency for AM 1.5 solar light to electricity has already attained 8-11%. The system is based on the sensitization of nanocrystalline oxide films by transition metal charge transfer sensitizers. In analogy to photosynthesis, the new chemical solar cell achieves the separation of the light absorption and charge carrier transport processes. Extraordinary yields for the conversion of incident photons into electric current are obtained, exceeding 90% for transition metal complexes within the wavelength range of their absorption band. The use of molten salt electrolytes together with coordination complexes of ruthenium as sensitizers and adequate sealing technology has endowed these cells with a remarkable stability making practical applications feasible. Seven industrial cooperations are presently involved in the development to bring these cells to the market. The first cells will be applied to supply electric power for consumer electronic devices. The launching of production of several products of this type is imminent and they should be on the market within the next two years. Quite aside from their intrinsic merits as photovoltaic device, the mesoscopic oxide semiconductor films developed in our laboratory offer attractive possibilities for a number of other applications. Thus, the first example of a nanocrystalline rocking chair battery will be demonstrated and its principle briefly discussed.

  14. Plasmolysis for efficient CO2 -to-fuel conversion

    Science.gov (United States)

    van Rooij, Gerard

    2015-09-01

    The strong non-equilibrium conditions provided by the plasma phase offer the opportunity to beat traditional thermal process energy efficiencies via preferential excitation of molecular vibrational modes. It is therefore a promising option for creating artificial solar fuels from CO2as raw material using (intermittently available) sustainable energy surpluses, which can easily be deployed within the present infrastructure for conventional fossil fuels. In this presentation, a common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures and conversion degrees, respectively. The results are interpreted on basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favourable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry still to dominate the initial experiments. Novel reactor approaches are proposed to tailor the plasma dynamics to achieve the non-equilibrium in which vibrational excitation is dominant. In collaboration with Dirk van den Bekerom, Niek den Harder, Teofil Minea, Dutch Institute For Fundamental Energy Research, Eindhoven, Netherlands; Gield Berden, Institute for Molecules and Materials, FELIX facility, Radboud University, Nijmegen, Netherlands; Richard Engeln, Applied Physics, Plasma en Materials Processing, Eindhoven University of Technology; and Waldo Bongers, Martijn Graswinckel, Erwin Zoethout, Richard van de Sanden, Dutch Institute For Fundamental Energy Research, Eindhoven, Netherlands.

  15. Thermochemical conversion of livestock wastes: carbonization of swine solids.

    Science.gov (United States)

    Ro, K S; Cantrell, K B; Hunt, P G; Ducey, T F; Vanotti, M B; Szogi, A A

    2009-11-01

    Slow pyrolysis or carbonization promotes the conversion of animal manures such as swine manure into charcoal. In this paper, the carbonizing kinetics of swine solids taken from different treatment stages were investigated with a thermogravimetric analyzer. Compared to their biologically stabilized counterpart (lagoon sludge) with an activation energy of 160 kJ mol(-1), the activation energies for fresh swine solid samples such as homogenized flushed manure and dewatered solids were much lower between 92 and 95 kJ mol(-1). Compared to the kinetics of first order decomposition of cellulose, the pyrolytic decomposition of the swine manures were more complex with the reaction orders varying at 3.7 and 5.0. The two different mathematical methods employed in this paper yielded the similar values of activation energy (E) and pre-exponential factor (A), confirming the validity of these methods. The results of this study provide useful information for development of farm-scale swine solid carbonization process. PMID:19442517

  16. Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic.

    Science.gov (United States)

    Kauffman, J Boone; Heider, Chris; Norfolk, Jennifer; Payton, Frederick

    2014-04-01

    Mangroves are recognized to possess a variety of ecosystem services including high rates of carbon sequestration and storage. Deforestation and conversion of these ecosystems continue to be high and have been predicted to result in significant carbon emissions to the atmosphere. Yet few studies have quantified the carbon stocks or losses associated with conversion of these ecosystems. In this study we quantified the ecosystem carbon stocks of three common mangrove types of the Caribbean as well as those of abandoned shrimp ponds in areas formerly occupied by mangrove-a common land-use conversion of mangroves throughout the world. In the mangroves of the Montecristi Province in Northwest Dominican Republic we found C stocks ranged from 706 to 1131 Mg/ha. The medium-statured mangroves (3-10 m in height) had the highest C stocks while the tall (> 10 m) mangroves had the lowest ecosystem carbon storage. Carbon stocks of the low mangrove (shrub) type (mangroves. Using a stock-change approach, the potential emissions from the conversion of mangroves to shrimp ponds ranged from 2244 to 3799 Mg CO2e/ha (CO2 equivalents). This is among the largest measured C emissions from land use in the tropics. The 6260 ha of mangroves and converted mangroves in the Montecristi Province are estimated to contain 3,841,490 Mg of C. Mangroves represented 76% of this area but currently store 97% of the carbon in this coastal wetland (3,696,722 Mg C). Converted lands store only 4% of the total ecosystem C (144,778 Mg C) while they comprised 24% of the area. By these metrics the replacement of mangroves with shrimp and salt ponds has resulted in estimated emissions from this region totaling 3.8 million Mg CO2e or approximately 21% of the total C prior to conversion. Given the high C stocks of mangroves, the high emissions from their conversion, and the other important functions and services they provide, their inclusion in climate-change mitigation strategies is warranted.

  17. Electrically assisted conversion of carbon dioxide into synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Czernichowski, A. [Faculte des Sciences, Orleans, 45 (France)

    1999-07-01

    CO{sub 2} is converted with the methane into a mixture of H{sub 2} and CO in a transferred arc or in a gliding discharge (GlidArc) reactor. Both electric devices generate very unstable but well controllable plasmas which show a high catalytic activity under relatively low (<700degC) gas temperature. In such conditions we obtain a non equilibrium and fast mixing conditions for the synthesis gas (SynGas) production. Experiments were performed under 1 -2 atm and at the gas flow rate of about 1 m{sup 3}(n)/h. A steam added into the biogas, high-CO{sub 2} natural gas or other CO{sub 2}/CH{sub 4} feed stock allows us to perform a mixed CO{sub 2}/H{sub 2}O conversion of light hydrocarbons (mainly methane) in order to obtain an ideal H{sub 2}/CO ({approx}) 2 molar ratio for further SynGas conversion into ultra clean hydrocarbon fuels through the Fischer-Tropsch synthesis. The energetic costs of such a SynGas produced in a laboratory prototype scale is already as low as 3 k Wh/m{sup 3}(n). Further improvements are expected in a demonstration SynGen reactor feeding a FT plant at the level of 4 barrels of liquid hydrocarbons a day, both units being under construction by Carbon Resources Ltd., Houston, TX. (Author)

  18. Evaluation of the conversion efficiency of the 180Nm3/h Johansson Biomass Gasifier™

    Directory of Open Access Journals (Sweden)

    Ntshengedzeni S. Mamphweli, Edson L. Meyer

    2010-01-01

    Full Text Available Biomass gasification is the thermochemical conversion of biomass materials into a producer gas, which is a mixture of carbon monoxide, carbon dioxide, methane, hydrogen, nitrogen and water vapour. The 180Nm3/h System Johansson Biomass Gasifier (SJBG at Eskom research and Innovation Centre is used for research and development initiatives, and also for demonstration purposes. The aim of this research was to investigate the efficiency of the gasifier and. This is done through an analysis of the gas profiles at the gasifier using a custom-built gas and temperature measurement system. Non-Dispersive Infrared gas detection technique is applied to monitor the volume and quality of producer gas. Palladium/Nickel gas sensing is applied to monitor the hydrogen content in the gas stream. Temperature in the gasifier is monitored through the use of type K thermocouples. The gas and temperature sensors are connected to the data logger interfaced to a computer. The heating value of the producer gas was determined from the percentage composition of the combustible gases. Evaluation of the efficiency of this gasifier was done before the installation of a 300Nm3/h at a rural village. The gasifier achieved an efficiency of 75% with an average gas heating value of 6MJ/Nm3.

  19. Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

    Science.gov (United States)

    You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

    2016-10-20

    Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. PMID:27474564

  20. Advanced Power Conversion and Distribution - Efficient Power for JPL Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We will develop a power conversion solution that will increase end-to-end efficiency to 80% or more compared to the 30%-50% efficiency typically obtained through...

  1. DOE-EFRC Center on Nanostructuring for Efficient Energy Conversion (CNEEC). Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Prinz, Friedrich B. [Stanford University; Bent, Stacey F. [Stanford University

    2015-10-22

    Stanford University’s DOE-EFRC Center on Nanostructuring for Efficient Energy Conversion (CNEEC) made important contributions in advancing our understanding of how nanostructuring of materials can enhance efficiency for solar energy conversion to produce hydrogen fuel and to solve fundamental cross-cutting problems. The overarching hypothesis underlying CNEEC the research projects was to control, synthesize and modify materials at the nanometer scale to increase the efficiency of energy conversion and storage devices and systems. In this pursuit, we emphasized the development of functional nanostructures that are based primarily on earth abundant and inexpensive materials. Efficient and cost effective synthetic routes for hydrogen production from sunlight provides a practical means for clean energy storage as well as an important alternative to fossil fuels. Hydrogen is an environmentally benign fuel that only produces water when burned or oxidized. However, more than 75% of the hydrogen consumed globally is produced commercially by steam reforming of methane that generates not only H2, but also the greenhouse gas CO2. In this regard, photoelectrochemical splitting of water into hydrogen (and oxygen) offers a carbon-free option. Producing hydrogen using renewable energy and widely available non-precious metal-based catalysts not only offers a cost effective process for solar-to-fuel conversion, but also provides great societal and environmental benefits towards mitigating global climate change. As a clean fuel and efficient energy carrier, hydrogen has the potential to provide large-scale energy storage and load leveling especially for intermittent power generation technologies such as wind and solar, and also serve as a carbon-free energy carrier for transportation and portable applications. However, photoelectrochemical splitting of water places strict demands on materials properties. To overcome these challenges, CNEEC developed theoretical and predictive

  2. 15% Power Conversion Efficiency from a Gated Nanotube/Silicon Nanowire Array Solar Cell

    Science.gov (United States)

    Petterson, Maureen K.; Lemaitre, Maxime G.; Shen, Yu; Wadhwa, Pooja; Hou, Jie; Vasilyeva, Svetlana V.; Kravchenko, Ivan I.; Rinzler, Andrew G.

    2015-03-01

    Despite their enhanced light trapping ability the performance of silicon nanowire array solar cells have, been stagnant with power conversion efficiencies barely breaking 10%. The problem is understood to be the consequence of a high photo-carrier recombination at the large surface area of the Si nanowire sidewalls. Here, by exploiting 1) electronic gating via an ionic liquid electrolyte to induce inversion in the n-type Si nanowires and 2) using a layer of single wall carbon nanotubes engineered to contact each nanowire tip and extract the minority carriers, we demonstrate silicon nanowire array solar cells with power conversion efficiencies of 15%. Our results allow for discrimination between the two principle means of avoiding front surface recombination: surface passivation and the use of local fields. A deleterious electrochemical reaction of the silicon due to the electrolyte gating is shown to be caused by oxygen/water entrained in the ionic liquid electrolyte. While encapsulation can avoid the issue a non-encapsulation based solution is also described. We gratefully acknowledge support from the National Science Foundation under ECCS-1232018.

  3. Photonic design for efficient solid state energy conversion

    Science.gov (United States)

    Agrawal, Mukul

    The efficiency of conversion between electrical and photonic energy in optoelectronic devices such as light-emitting diodes, photodetectors and solar cells is strongly affected by the photonic modes supported by the device structure. In this thesis, we show how tuning of the local photon density of states in subwavelength structures can be used to optimize device performance. The first part of the thesis is focused on organic light emitting diodes (OLEDs), a candidate technology for next-generation displays and solid-state lighting. An important unsolved problem in OLEDs is to ensure that a significant fraction of photons emitted by the organic emissive layer couple out of the device structure instead of remaining trapped in the device. It is shown using modeling and experiments that optimized non-periodic dielectric multilayer stacks can significantly increase the photon outcoupling while maintaining display quality brightness uniformity over the viewing cone. In the second part, we discuss the theoretical limits to broadband light harvesting in photovoltaic cells. First, it is shown that the extent to which one-dimensional optical cavities can be used to enhance light absorption over a broad spectral range is limited by the requirement that the cavity mirrors have a causal response. This result is used as a guide to design practical dielectric structures that enhance light harvesting in planar thin-film organic solar cells. Finally, we consider the enhancement of optical absorption in two- and three-dimensional structures in which incident light is scattered into quasi-trapped modes for more effective utilization of solar radiation. It is shown that there is an upper bound to the degree to which optical absorption can be enhanced that is identical to the limit found in the geometric optics regime. Rigorous optical simulations are used to show that an optical structure consisting of a two-dimensional array of inverted pyramids comes close to this limit. Before

  4. On the Energy Conversion Efficiency of Piezoelectric Vibration Energy Harvesting Devices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Eun [Catholic University of Daegu, Kyungsan (Korea, Republic of)

    2015-05-15

    To properly design and assess a piezoelectric vibration energy harvester, it is necessary to consider the application of an efficiency measure of energy conversion. The energy conversion efficiency is defined in this work as the ratio of the electrical output power to the mechanical input power for a piezoelectric vibration energy harvester with an impedance-matched load resistor. While previous research works employed the electrical output power for approximate impedance-matched load resistance, this work derives an efficiency measure considering optimally matched resistance. The modified efficiency measure is validated by comparing it with finite element analysis results for piezoelectric vibration energy harvesters with three different values of the electro-mechanical coupling coefficient. New findings on the characteristics of energy conversion and conversion efficiency are also provided for the two different impedance matching methods.

  5. Single-cell concepts for obtaining photovoltaic conversion efficiency over 30 percent

    Science.gov (United States)

    Fan, John C. C.

    1985-01-01

    Although solar photovoltaic conversion efficiencies over 30 percent (one sun, AM1) can be expected for multiple-cell configurations using spectral splitting techniques, the highest practical single-cell conversion efficiency that can be attained using present concepts is estimated to be about 27-28 percent. To achieve conversion efficiencies above 30 percent using single-cell configurations it will be necessary to employ different concepts, such as spectral compression and broad-band detection. The implementation of these concepts would require major breakthroughs that are not anticipated in the near future.

  6. Ultrabroad-band wavelength converter with high flattening conversion efficiency in a semiconductor optical amplifier

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Xu(徐晓峰); Jue Wei(韦珏); Zhihui Kang(康智慧); Yun Jiang(姜云); Huifang Zhang(张惠芳); Jinyue Gao(高锦岳)

    2004-01-01

    The efficiency of ultrabroad-band wavelength conversion using orthogonal-pump four-wave mixing in a semiconductor optical amplifier is measured for the wavelength shifts from 1500 to 1640 nm. The variation of conversion efficiency is < 0.9 dB over the wavelength range from 1530 to 1560 nm (C-band), and < 4.5dB over the wavelength range from 1560 to 1610 nm (L-band). The maximum conversion efficiency is about -8.7 dB.

  7. Thermoelectric conversion efficiency in IV-VI semiconductors with reduced thermal conductivity

    Science.gov (United States)

    Ishida, Akihiro; Thao, Hoang Thi Xuan; Yamamoto, Hidenari; Kinoshita, Yohei; Ishikiriyama, Mamoru

    2015-10-01

    Mid-temperature thermoelectric conversion efficiencies of the IV-VI materials were calculated under the Boltzmann transport theory of carriers, taking the Seebeck, Peltier, and Thomson effects into account. The conversion efficiency was discussed with respect to the lattice thermal conductivity, keeping other parameters such as Seebeck coefficient and electrical conductivity to the same values. If room temperature lattice thermal conductivity is decreased up to 0.5W/mK, the conversion efficiency of a PbS based material becomes as high as 15% with the temperature difference of 500K between 800K and 300K.

  8. Thermoelectric conversion efficiency in IV-VI semiconductors with reduced thermal conductivity

    Directory of Open Access Journals (Sweden)

    Akihiro Ishida

    2015-10-01

    Full Text Available Mid-temperature thermoelectric conversion efficiencies of the IV-VI materials were calculated under the Boltzmann transport theory of carriers, taking the Seebeck, Peltier, and Thomson effects into account. The conversion efficiency was discussed with respect to the lattice thermal conductivity, keeping other parameters such as Seebeck coefficient and electrical conductivity to the same values. If room temperature lattice thermal conductivity is decreased up to 0.5W/mK, the conversion efficiency of a PbS based material becomes as high as 15% with the temperature difference of 500K between 800K and 300K.

  9. Changes in soil carbon cycling accompanying conversion of row-crop fields to grazing dairy pastures

    Science.gov (United States)

    Thompson, A.; Kramer, M. G.; Hill, N.; Machmuller, M. B.; Cyle, K.

    2011-12-01

    Increasingly, the dairy industry in the eastern US is transitioning from total confinement dairy systems (TCD) toward pasture-based, management intensive grazing dairy (MiGD) systems. This transition is driven by the fact that MiGDs require substantially less operating capital and are more economically efficient than TCD systems. Consequently, the impact of this transition and shift in land-use practice on carbon dynamics may be considerable. Land-use in a Management intensive Grazing Dairy (MiGD) system is fundamentally different than conventional confinement dairies and conventional no-till pastures. The forage system involves rotational grazing at optimal digestibility, when the plants are immature (~20-days) and consequently protein-rich. MiGD cows spend >90% of their time in the field and deposit > 90% of their waste directly to the soil surface. Thus, little above ground plant residues are directly returned to the soil, but rather substantial C inputs derive from bovine manure. We sampled a MiGD-chronosequence of row-crop to MiGD conversion established in 2007 in eastern Georgia. All soils across the MiGD-chronosequence, all occur in relative (40 km) close proximity to one another, are deep, well-drained, fine and fine sandy loam Ultisols formed on Coastal Plain sediments. Prior to MiGD established, the soils were farmed for > 50 yrs using conventional tillage techniques. Our current sampling to 1m depths captures fields at 0, 2, 3, and 5 yrs since conversion. Total soil carbon (C) and the carbon concentration of the clay fraction increased following conversion, with the greatest increases occurring between 3 and 5 yrs since conversion. These C increases were limited to the upper 40cm of the soil, with minimal change occurring at depth. Characterization of the protein and ligand content of these soils via 13C NMR and chemolytic techniques as a function of soil particle density and size is in progress and will be presented along with estimates of carbon

  10. DOE-EFRC Center on Nanostructuring for Efficient Energy Conversion (CNEEC)

    Energy Technology Data Exchange (ETDEWEB)

    Prinz, Friedrich B. [Stanford Univ., CA (United States). Mechanical Engineering. Materials Science and Engineering; Bent, Stacey F. [Stanford Univ., CA (United States). Chemical Engineering

    2015-10-22

    CNEEC’s mission has been to understand how nanostructuring of materials can enhance efficiency for solar energy conversion to produce hydrogen fuel and to solve fundamental cross-cutting problems. The overarching hypothesis underlying CNEEC research was that controlling, synthesizing and modifying materials at the nanometer scale increases the efficiency of energy conversion and storage devices and systems. In this pursuit, we emphasized the development of functional nanostructures that are based primarily on earth abundant and inexpensive materials.

  11. Market efficiency in the European carbon markets

    International Nuclear Information System (INIS)

    In this paper, we study the relationship between futures and spot prices in the European carbon markets from the cost-of-carry hypothesis. The aim is to investigate the extent of efficiency market. The three main European markets (BlueNext, EEX and ECX) are analyzed during Phase II, covering the period from March 13, 2009 to January, 17, 2012. Futures contracts are found to be cointegrated with spot prices and interest rates for several maturities in the three CO2 markets. Results are similar when structural breaks are taken into account. According to individual and joint tests, the cost-of-carry model is rejected for all maturities and CO2 markets, implying that neither contract is priced according to the cost-of-carry model. The absence of the cost-of-carry relationship can be interpreted as an indicator of market inefficiency and may bring arbitrage opportunities in the CO2 market. - Highlights: • We study the cost-of-carry hypothesis in the European carbon markets during Phase 2. • We apply cointegration tests with and without structural breaks on several maturities. • We find that futures contracts are cointegrated with spot prices and interest rates. • The cost-of-carry model is rejected for all maturities and carbon markets

  12. Buckled graphene for efficient energy harvest, storage and conversion

    Science.gov (United States)

    Jiang, Jin-Wu

    2016-10-01

    Buckling is one of the most common phenomena in atom-thick layered structures like graphene. While the buckling phenomenon usually causes disaster for most nanodevices, we illustrate one positive application of buckled graphene for energy harvest, storage and conversion. More specifically, we perform molecular dynamical simulations to show that buckled graphene can be used to collect wasted mechanical energy and store the energy in the form of internal knotting potential. Through strain engineering, the knotting potential can be converted into useful kinetic (thermal) energy that is highly concentrated at the free edges of buckled graphene. The present study demonstrates potential applications of buckled graphene for converting dispersed wasted mechanical energy into concentrated useful kinetic (thermal) energy.

  13. Buckled graphene for efficient energy harvest, storage and conversion.

    Science.gov (United States)

    Jiang, Jin-Wu

    2016-10-01

    Buckling is one of the most common phenomena in atom-thick layered structures like graphene. While the buckling phenomenon usually causes disaster for most nanodevices, we illustrate one positive application of buckled graphene for energy harvest, storage and conversion. More specifically, we perform molecular dynamical simulations to show that buckled graphene can be used to collect wasted mechanical energy and store the energy in the form of internal knotting potential. Through strain engineering, the knotting potential can be converted into useful kinetic (thermal) energy that is highly concentrated at the free edges of buckled graphene. The present study demonstrates potential applications of buckled graphene for converting dispersed wasted mechanical energy into concentrated useful kinetic (thermal) energy.

  14. Efficient solar-driven synthesis, carbon capture, and desalinization, STEP: solar thermal electrochemical production of fuels, metals, bleach.

    Science.gov (United States)

    Licht, S

    2011-12-15

    STEP (solar thermal electrochemical production) theory is derived and experimentally verified for the electrosynthesis of energetic molecules at solar energy efficiency greater than any photovoltaic conversion efficiency. In STEP the efficient formation of metals, fuels, chlorine, and carbon capture is driven by solar thermal heated endothermic electrolyses of concentrated reactants occuring at a voltage below that of the room temperature energy stored in the products. One example is CO(2) , which is reduced to either fuels or storable carbon at a solar efficiency of over 50% due to a synergy of efficient solar thermal absorption and electrochemical conversion at high temperature and reactant concentration. CO(2) -free production of iron by STEP, from iron ore, occurs via Fe(III) in molten carbonate. Water is efficiently split to hydrogen by molten hydroxide electrolysis, and chlorine, sodium, and magnesium from molten chlorides. A pathway is provided for the STEP decrease of atmospheric carbon dioxide levels to pre-industial age levels in 10 years.

  15. Weak-signal conversion from 1550nm to 532nm with 84% efficiency

    CERN Document Server

    Samblowski, Aiko; Baune, Christoph; Fiurasek, Jaromir; Schnabel, Roman

    2013-01-01

    We report on the experimental frequency conversion of a dim, coherent continuous-wave light field from 1550nm to 532nm with an external photon-number conversion efficiency of (84.4 +/- 1.5)%. We used sum-frequency generation, which was realized in a standing-wave cavity built around a periodically poled type I potassium titanyl phosphate (PPKTP) crystal, pumped by an intense field at 810 nm. Our result is in full agreement with a numerical model. For optimized cavity coupler reflectivities it predicts a conversion efficiency of up to 93% using the same PPKTP crystal.

  16. Synergistic Carbon Dioxide Capture and Conversion in Porous Materials.

    Science.gov (United States)

    Zhang, Yugen; Lim, Diane S W

    2015-08-24

    Global climate change and excessive CO2 emissions have caused widespread public concern in recent years. Tremendous efforts have been made towards CO2 capture and conversion. This has led to the development of numerous porous materials as CO2 capture sorbents. Concurrently, the conversion of CO2 into value-added products by chemical methods has also been well-documented recently. However, realizing the attractive prospect of direct, in situ chemical conversion of captured CO2 into other chemicals remains a challenge.

  17. Efficiency of non-optimized direct carbon fuel cell with molten alkaline electrolyte fueled by carbonized biomass

    Science.gov (United States)

    Kacprzak, A.; Kobyłecki, R.; Włodarczyk, R.; Bis, Z.

    2016-07-01

    The direct carbon fuel cells (DCFCs) belong to new generation of energy conversion devices that are characterized by much higher efficiencies and lower emission of pollutants than conventional coal-fired power plants. In this paper the DCFC with molten hydroxide electrolyte is considered as the most promising type of the direct carbon fuel cells. Binary alkali hydroxide mixture (NaOH-LiOH, 90-10 mol%) is used as electrolyte and the biochar of apple tree origin carbonized at 873 K is applied as fuel. The performance of a lab-scale DCFC with molten alkaline electrolyte is investigated and theoretical, practical, voltage, and fuel utilization efficiencies of the cell are calculated and discussed. The practical efficiency is assessed on the basis of fuel HHV and LHV and the values are estimated at 40% and 41%, respectively. The average voltage efficiency is calculated as roughly 59% (at 0.65 V) and it is in a relatively good agreement with the values obtained by other researchers. The calculated efficiency of fuel utilization exceeds 95% thus indicating a high degree of carbon conversion into the electric power.

  18. Estimation of frequency conversion efficiency of THz devices using a ballistic electron wave swing circuit model

    International Nuclear Information System (INIS)

    The ballistic electron wave swing device has previously been presented as a possible candidate for a simple power conversion technique to the THz -domain. This paper gives a simulative estimation of the power conversion efficiency. The harmonic balance simulations use an equivalent circuit model, which is also derived in this work from a mechanical model. To verify the validity of the circuit model, current waveforms are compared to Monte Carlo simulations of identical setups. Model parameters are given for a wide range of device configurations. The device configuration exhibiting the most conforming waveform is used further for determining the best conversion efficiency. The corresponding simulation setup is described. Simulation results implying a conversion efficiency of about 22% are presented. (paper)

  19. Estimation of frequency conversion efficiency of THz devices using a ballistic electron wave swing circuit model

    Science.gov (United States)

    Schildbach, Christian; Ong, Duu Sheng; Hartnagel, Hans; Schmidt, Lorenz-Peter

    2016-06-01

    The ballistic electron wave swing device has previously been presented as a possible candidate for a simple power conversion technique to the THz -domain. This paper gives a simulative estimation of the power conversion efficiency. The harmonic balance simulations use an equivalent circuit model, which is also derived in this work from a mechanical model. To verify the validity of the circuit model, current waveforms are compared to Monte Carlo simulations of identical setups. Model parameters are given for a wide range of device configurations. The device configuration exhibiting the most conforming waveform is used further for determining the best conversion efficiency. The corresponding simulation setup is described. Simulation results implying a conversion efficiency of about 22% are presented.

  20. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    OpenAIRE

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-...

  1. Multiscale-tailored bioelectrode surfaces for optimized catalytic conversion efficiency.

    Science.gov (United States)

    Bon Saint Côme, Yémima; Lalo, Hélène; Wang, Zhijie; Etienne, Mathieu; Gajdzik, Janine; Kohring, Gert-Wieland; Walcarius, Alain; Hempelmann, Rolf; Kuhn, Alexander

    2011-10-18

    We describe the elaboration of a multiscale-tailored bioelectrocatalytic system. The combination of two enzymes, D-sorbitol dehydrogenase and diaphorase, is studied with respect to the oxidation of D-sorbitol as a model system. The biomolecules are immobilized in an electrodeposited paint (EDP) layer. Reproducible and efficient catalysis of D-sorbitol oxidation is recorded when this system is immobilized on a gold electrode modified by a self-assembled monolayer of 4-carboxy-(2,5,7-trinitro-9-fluorenylidene)malonitrile used as a mediator. The insertion of mediator-modified gold nanoparticles into the EDP film increases significantly the active surface area for the catalytic reaction, which can be further enhanced when the whole system is immobilized in macroporous gold electrodes. This multiscale architecture finally leads to a catalytic device with optimized efficiency for potential use in biosensors, bioelectrosynthesis, and biofuel cells.

  2. Rationally designed, three-dimensional carbon nanotube back-contacts for efficient solar devices

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Cary L.; Takei, Kuniharu; Kapadia, Rehan; Zheng, Maxwell; Ford, Alexandra C.; Zhang, Junjun [Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA (United States); Jamshidi, Arash; Wu, Ming [Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA (United States); Bardhan, Rizia; Urban, Jeffrey J. [Molecular Foundry Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Ager, Joel W. [Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Oye, Michael M. [NASA Ames Research Center, Moffett Field, CA (United States); Javey, Ali [Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2011-11-15

    Structure matters in solar-to-fuel conversion efficiency, demonstrated for TiO{sub 2} coated onto designed three-dimensional (3-D) carbon nanofiber scaffolds. Performance enhancement of up to three times compared to flat films can be mostly attributed to structurally-enhanced carrier collection and photon management processes. Using 3-D templates to balance light absorption depth and carrier collection can lead to a new class of high efficiency and cheap energy conversion devices. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. The TOPSIS Evaluation on Carbon Emission Economic Efficiency

    Institute of Scientific and Technical Information of China (English)

    Sheng; XU; Chao; ZHANG; Juan; YANG

    2013-01-01

    Based on carbon emission data of 17 cities in Shandong Province in 2005-2009,this paper analyzes carbon emission economic efficiency. It conducts weight distribution by the Ordered Weighted Averaging ( OWA) method,and takes systematic evaluation on carbon emission economic efficiency using TOPSIS method. In eastern coastal regions,including Dongying,Yantai,Weihai and Qingdao,the carbon emission economic efficiency is generally higher than inland regions of Shandong Province. The conclusion reached after correction of time weight is basically consistent with traditional TOPSIS overall evaluation,further proves validity of the evaluation. Finally,it gives recommendations for improving carbon emission economic efficiency in Shandong Province.

  4. Improvement of conversion efficiency of silicon solar cells using up-conversion molybdate La2Mo2O9:Yb,R (R=Er, Ho) phosphors

    Institute of Scientific and Technical Information of China (English)

    Yen-Chi Chen; Teng-Ming Chen

    2011-01-01

    The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle,which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response.In this study,the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the ncar-infiared spectral range.The short circuit current (Isc),open circuit voltage (Voc),and conversion efficiency (η) of spectral conversion cells were measured.Preliminary experimental results revealed that the light conversion efficiency of a 1.5%-2.7% increase in Si-based cell was achieved.

  5. Thermal underwear. [Energy efficient conversion of Victorian terraced house

    Energy Technology Data Exchange (ETDEWEB)

    Chevin, D.

    1992-01-01

    In a conversion scheme the original masonry will be retained and superinsulated to give a U-value of 0.2 W/m{sup 2}K, and the windows will be insulated with three layers of low-E glass. The building's innards will be ripped out and replaced with a new timber frame of glulam trusses supported by the original loadbearing walls. A distance of 60 cm from the external wall, a new inside skin of semi-translucent panels will be constructed. In cold weather, the panels will remain closed, creating a bank of still air. In warmer weather they can be slid back to increase the living area of each flat. The floor between the two walls on each level is made of glass to increase the daylight within the centre of the building. Sunscoops on the roof level will reflect extra daylight down into the periphery. Energy for space heating and hot water will come from a communal ''solar system'' at the top of the building. On its sloping south side, the timber-framed structure will be fully glazed with glass and polyester sheeting which has reflective louvres sandwiched between those two layers to reduce heat gain during the summer. Heat from rooftop solar collectors is channelled into a communal hot water tank. The flats will be heated by fanning air warmed in the solar attic through a duct down to underfloor vents beneath each dwelling. The attic will be kept hot by using the sun to warm water contained in 250, 14-litre belljars stored there. Filtered air is drawn into the attic, up though vents at the bottom of the south-west facing stairwell and over fragrant plants chosen to absorb organic pollutants. Solar gain from the glazed stairwell warms the air, causing it to rise. Additional energy is saved by extracting heat from this rising fresh air through a heat exchanger. (Author).

  6. CRADA Final Report for CRADA Number NFE-10-02991 "Development and Commercialization of Alternative Carbon Precursors and Conversion Technologies"

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Rober [ORNL; Paulauskas, Felix [ORNL; Naskar, Amit [ORNL; Kaufman, Michael [ORNL; Yarborough, Ken [ORNL; Derstine, Chris [The Dow Chemical Company

    2013-10-01

    The overall objective of the collaborative research performed by the Oak Ridge National Laboratory (ORNL) and the Dow Chemical Company under this Cooperative Research And Development Agreement (CRADA NFE-10-02991) was to develop and establish pathways to commercialize new carbon fiber precursor and conversion technology. This technology is to produce alternative polymer fiber precursor formulations as well as scaled energy-efficient advanced conversion technology to enable continuous mode conversion to obtain carbonized fibers that are technically and economically viable in industrial markets such as transportation, wind energy, infrastructure and oil drilling applications. There have been efforts in the past to produce a low cost carbon fiber. These attempts have to be interpreted against the backdrop of the market needs at the time, which were strictly military aircraft and high-end aerospace components. In fact, manufacturing costs have been reduced from those days to current practice, where both process optimization and volume production have enabled carbon fiber to become available at prices below $20/lb. However, the requirements of the lucrative aerospace market limits further price reductions from current practice. This approach is different because specific industrial applications are targeted, most specifically wind turbine blade and light vehicle transportation, where aircraft grade carbon fiber is not required. As a result, researchers are free to adjust both manufacturing process and precursor chemistry to meet the relaxed physical specifications at a lower cost. This report documents the approach and findings of this cooperative research in alternative precursors and advanced conversion for production of cost-effective carbon fiber for energy missions. Due to export control, proprietary restrictions, and CRADA protected data considerations, specific design details and processing parameters are not included in this report.

  7. Oecophylla smaragdina food conversion efficiency: prospects for ant farming

    DEFF Research Database (Denmark)

    Offenberg, Hans Joachim

    2011-01-01

    Oecophylla ants are sold at high prices on several commercial markets as a human delicacy, as pet food or as traditional medicine. Currently markets are supplied by ants collected from the wild; however, an increasing interest in ant farming exists as all harvest is easily sold and as ant farming...... selling prices these efficiencies led to rates of return from 1.52 to 4.56, respectively, if: (i) protein is supplied from commercial products; or (ii) alternatively supplied from free sources such as insects and kitchen waste. These results suggest that Oecophylla ant farming may become highly profitable...

  8. Understanding hydrothermal carbonization of mixed feedstocks for waste conversion

    Science.gov (United States)

    Lu, Xiaowei

    Hydrothermal carbonization (HTC) is an environmentally beneficial means to convert waste materials to value-added solid and liquid products with minimal greenhouse gas emission. Research is lacking on understanding the influence of critical process conditions on product formation and environmental implication associated with HTC of waste streams. This work was conducted to determine how reaction conditions and heterogeneous compound mixtures (representative of municipal wastes) influence hydrothermal carbonization processes. The specific experiments include: (1) determine how carbonization product properties are manipulated by controlling feedstock composition, process conditions, and catalyst addition; (2) determine if carbonization of heterogeneous mixtures follows similar pathways as that with pure feedstocks; and (3) evaluate and compare the carbon and energy-related implications associated with carbonization products with those associated with other common waste management processes for solid waste.

  9. Maximum efficiency of state-space models of nanoscale energy conversion devices

    Science.gov (United States)

    Einax, Mario; Nitzan, Abraham

    2016-07-01

    The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.

  10. Maximum efficiency of state-space models of nanoscale energy conversion devices.

    Science.gov (United States)

    Einax, Mario; Nitzan, Abraham

    2016-07-01

    The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.

  11. Maximum efficiency of state-space models of nanoscale energy conversion devices.

    Science.gov (United States)

    Einax, Mario; Nitzan, Abraham

    2016-07-01

    The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage. PMID:27394100

  12. Reversible and efficient conversion between microwave and optical light

    CERN Document Server

    Andrews, R W; Purdy, T P; Cicak, K; Simmonds, R W; Regal, C A; Lehnert, K W

    2013-01-01

    Converting low-frequency electrical signals into much higher frequency optical signals has enabled modern communications networks to leverage both the strengths of microfabricated electrical circuits and optical fiber transmission, allowing information networks to grow in size and complexity. A microwave-to-optical converter in a quantum information network could provide similar gains by linking quantum processors via low-loss optical fibers and enabling a large-scale quantum network. However, no current technology can convert low-frequency microwave signals into high-frequency optical signals while preserving their fragile quantum state. For this demanding application, a converter must provide a near-unitary transformation between different frequencies; that is, the ideal transformation is reversible, coherent, and lossless. Here we demonstrate a converter that reversibly, coherently, and efficiently links the microwave and optical portions of the electromagnetic spectrum. We use our converter to transfer cl...

  13. Estimating global "blue carbon" emissions from conversion and degradation of vegetated coastal ecosystems.

    Directory of Open Access Journals (Sweden)

    Linwood Pendleton

    Full Text Available Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystems--marshes, mangroves, and seagrasses--that may be lost with habitat destruction ('conversion'. Relatively unappreciated, however, is that conversion of these coastal ecosystems also impacts very large pools of previously-sequestered carbon. Residing mostly in sediments, this 'blue carbon' can be released to the atmosphere when these ecosystems are converted or degraded. Here we provide the first global estimates of this impact and evaluate its economic implications. Combining the best available data on global area, land-use conversion rates, and near-surface carbon stocks in each of the three ecosystems, using an uncertainty-propagation approach, we estimate that 0.15-1.02 Pg (billion tons of carbon dioxide are being released annually, several times higher than previous estimates that account only for lost sequestration. These emissions are equivalent to 3-19% of those from deforestation globally, and result in economic damages of $US 6-42 billion annually. The largest sources of uncertainty in these estimates stems from limited certitude in global area and rates of land-use conversion, but research is also needed on the fates of ecosystem carbon upon conversion. Currently, carbon emissions from the conversion of vegetated coastal ecosystems are not included in emissions accounting or carbon market protocols, but this analysis suggests they may be disproportionally important to both. Although the relevant science supporting these initial estimates will need to be refined in coming years, it is clear that policies encouraging the sustainable management of coastal ecosystems could significantly reduce carbon emissions from the land-use sector, in addition to sustaining the well-recognized ecosystem services of coastal habitats.

  14. Efficient single sideband microwave to optical conversion using an electro-optical whispering gallery mode resonator

    CERN Document Server

    Rueda, Alfredo; Collodo, Michele C; Vogl, Ulrich; Stiller, Birgit; Schunk, Gerhard; Strekalov, Dmitry V; Marquardt, Christoph; Fink, Johannes M; Painter, Oskar; Leuchs, Gerd; Schwefel, Harald G L

    2016-01-01

    Linking classical microwave electrical circuits to the optical telecommunication band is at the core of modern communication. Future quantum information networks will require coherent microwave-to-optical conversion to link electronic quantum processors and memories via low-loss optical telecommunication networks. Efficient conversion can be achieved with electro-optical modulators operating at the single microwave photon level. In the standard electro-optic modulation scheme this is impossible because both, up- and downconverted, sidebands are necessarily present. Here we demonstrate true single sideband up- or downconversion in a triply resonant whispering gallery mode resonator by explicitly addressing modes with asymmetric free spectral range. Compared to previous experiments, we show a three orders of magnitude improvement of the electro-optical conversion efficiency reaching 0.1% photon number conversion for a 10GHz microwave tone at 0.42mW of optical pump power. The presented scheme is fully compatible...

  15. Effect of carbon monoxide, hydrogen and sulfate on thermophilic (55 degrees C) hydrogenogenic carbon monoxide conversion in two anaerobic bioreactor sludges.

    Science.gov (United States)

    Sipma, J; Meulepas, R J W; Parshina, S N; Stams, A J M; Lettinga, G; Lens, P N L

    2004-04-01

    The conversion routes of carbon monoxide (CO) at 55 degrees C by full-scale grown anaerobic sludges treating paper mill and distillery wastewater were elucidated. Inhibition experiments with 2-bromoethanesulfonate (BES) and vancomycin showed that CO conversion was performed by a hydrogenogenic population and that its products, i.e. hydrogen and CO2, were subsequently used by methanogens, homo-acetogens or sulfate reducers depending on the sludge source and inhibitors supplied. Direct methanogenic CO conversion occurred only at low CO concentrations [partial pressure of CO (PCO) hydrogen production from CO, especially since after 30 min exposure to 95 degrees C, the production of CH4 at 55 degrees C was negligible. The paper mill sludge was capable of sulfate reduction with hydrogen, tolerating and using high CO concentrations (PCO>1.6 bar), indicating that CO-rich synthesis gas can be used efficiently as an electron donor for biological sulfate reduction.

  16. Solar energy conversion via hot electron internal photoemission in metallic nanostructures: Efficiency estimates

    International Nuclear Information System (INIS)

    Collection of hot electrons generated by the efficient absorption of light in metallic nanostructures, in contact with semiconductor substrates can provide a basis for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion efficiency of systems that rely on internal photoemission processes at metal-semiconductor Schottky-barrier diodes. In this theory, the current-voltage characteristics are given by the internal photoemission yield as well as by the thermionic dark current over a varied-energy barrier height. The Fowler model, in all cases, predicts solar energy-conversion efficiencies of <1% for such systems. However, relaxation of the assumptions regarding constraints on the escape cone and momentum conservation at the interface yields solar energy-conversion efficiencies as high as 1%–10%, under some assumed (albeit optimistic) operating conditions. Under these conditions, the energy-conversion efficiency is mainly limited by the thermionic dark current, the distribution of hot electron energies, and hot-electron momentum considerations

  17. Transition metal oxide-carbon composites as conversion anodes for sodium-ion battery

    International Nuclear Information System (INIS)

    Herein, we characterize various metal oxide-carbon composites, i.e. CuO-MCMB (mesocarbon microbeads), Fe2O3–MCMB and NiO-MCMB, as anode materials for application in sodium-ion battery. The electrodes, supposed to react through a conversion mechanism, are studied in terms of structure, morphology and electrochemical behavior in sodium cell. The results demonstrate a specific capacity of the order of 100 mAh g−1 for Fe2O3–MCMB and NiO-MCMB, and of about 300 mAh g−1 for CuO-MCMB. The remarkable performance of the latter suggests the copper oxide-based electrode as the preferred anode material for battery application. Indeed, further study aimed to clarify the Na/CuO-MCMB reaction mechanism is performed by ex-situ X-ray diffraction on electrode material cast onto aluminum support. The study suggests a partial conversion reaction for CuO-based anode that is considered suitable candidate in replacement of sodium metal, in efficient and safe Na-ion battery

  18. A novel MPPT method for enhancing energy conversion efficiency taking power smoothing into account

    International Nuclear Information System (INIS)

    Highlights: • We discuss the disadvantages of conventional OTC MPPT method. • We study the relationship between enhancing efficiency and power smoothing. • The conversion efficiency is enhanced and the volatility of power is suppressed. • Small signal analysis is used to verify the effectiveness of proposed method. - Abstract: With the increasing capacity of wind energy conversion system (WECS), the rotational inertia of wind turbine is becoming larger. And the efficiency of energy conversion is significantly reduced by the large inertia. This paper proposes a novel maximum power point tracking (MPPT) method to enhance the efficiency of energy conversion for large-scale wind turbine. Since improving the efficiency may increase the fluctuations of output power, power smoothing is considered as the second control objective. A T-S fuzzy inference system (FIS) is adapted to reduce the fluctuations according to the volatility of wind speed and accelerated rotor speed by regulating the compensation gain. To verify the effectiveness, stability and good dynamic performance of the new method, mechanism analyses, small signal analyses, and simulation studies are carried out based on doubly-fed induction generator (DFIG) wind turbine, respectively. Study results show that both the response speed and the efficiency of proposed method are increased. In addition, the extra fluctuations of output power caused by the high efficiency are reduced effectively by the proposed method with FIS

  19. Efficient conversion of solar energy to biomass and electricity.

    Science.gov (United States)

    Parlevliet, David; Moheimani, Navid Reza

    2014-01-01

    The Earth receives around 1000 W.m(-2) of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture.

  20. High-efficiency microwave photonic harmonic down-conversion with tunable and reconfigurable filtering.

    Science.gov (United States)

    Liao, Jinxin; Zheng, Xiaoping; Li, Shangyuan; Zhang, Hanyi; Zhou, Bingkun

    2014-12-01

    A new optical-frequency comb-based microwave photonic harmonic down-convertor with tunable and reconfigurable filtering is proposed and experimentally demonstrated. The coherent evenly spaced optical carriers offer harmonic down-conversion for ultrahigh radio frequency signals with low-frequency local oscillator, and construct a tunable and reconfigurable bandpass filter for the intermediate-frequency (IF) signal combined with dispersion. This implementation features high conversion efficiency. Experimental results show the filtered output IF signal has a clean spectrum with high quality. Measured conversion loss is 8.3 dB without extra electrical amplification. PMID:25490622

  1. DBD in burst mode: solution for more efficient CO2 conversion?

    Science.gov (United States)

    Ozkan, A.; Dufour, T.; Silva, T.; Britun, N.; Snyders, R.; Reniers, F.; Bogaerts, A.

    2016-10-01

    CO2 conversion into value-added products has gained significant interest over the few last years, as the greenhouse gas concentrations constantly increase due to anthropogenic activities. Here we report on experiments for CO2 conversion by means of a cold atmospheric plasma using a cylindrical flowing dielectric barrier discharge (DBD) reactor. A detailed comparison of this DBD ignited in a so-called burst mode (i.e. where an AC voltage is applied during a limited amount of time) and pure AC mode is carried out to evaluate their effect on the conversion of CO2 as well as on the energy efficiency. Decreasing the duty cycle in the burst mode from 100% (i.e. corresponding to pure AC mode) to 40% leads to a rise in the conversion from 16-26% and to a rise in the energy efficiency from 15 to 23%. Based on a detailed electrical analysis, we show that the conversion correlates with the features of the microfilaments. Moreover, the root-mean-square voltage in the burst mode remains constant as a function of the process time for the duty cycles  plasma voltage in the burst mode yields a higher electric field. This causes the increasing the electron energy, and therefore their involvement in the CO2 dissociation process, which is an additional explanation for the higher CO2 conversion and energy efficiency in the burst mode.

  2. Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

    Science.gov (United States)

    Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

    2016-01-01

    Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

  3. Low Threshold and High Conversion Efficiency Nanosecond Mid-Infrared KTA OPO

    Institute of Scientific and Technical Information of China (English)

    ZHONG Kai; LI Jian-Song; CUI Hai-Xia; XU Deng-Gang; WANG Yu-Ye; ZHOU Rui; WANG Jing-Li; WANG Peng; YAO Jian-Quan

    2009-01-01

    Based on a Type Ⅱ non-critically phase-matched KTA crystal,a low-threshold and high conversion efficiency midinfrared optical parametric oscillator(OPO)pumped by a diode-end-pumped Nd:YVO_4 laser is demonstrated.The OPO threshold is only 0.825 W.The maximum output power of 435mW at 3.47μm is achieved with the repetition rate of 30kHz,corresponding to an optical-to-optical conversion efficiency of 4.4%.The photon conversion efficiency is as high as about 64%.The pulse width is 3.5 ns with a peak power of 4 kW for the maximum output power.

  4. Enhanced Solar Photoelectrochemical Conversion Efficiency of ZnO:Cu Electrodes for Water-Splitting Application

    Directory of Open Access Journals (Sweden)

    Rekha Dom

    2013-01-01

    Full Text Available n-type ZnO:Cu photoanodes were fabricated by simple spray pyrolysis deposition technique. Influence of low concentration (range ~10−4–10−1% of Cu doping in hexagonal ZnO lattice on its photoelectrochemical performance has been investigated. The doped photoanodes displayed 7-time enhanced conversion efficiencies with respect to their undoped counterpart, as estimated from the photocurrents generated under simulated solar radiation. This is the highest enhancement in the solar conversion efficiency reported so far for the Cu-doped ZnO. This performance is attributed to the red shift in the band gap of the Cu-doped films and is in accordance with the incident-photon-current-conversion efficiency (IPCE measurements. Electrochemical studies reveal an n-type nature of these photoanodes. Thus, the study indicates a high potential of doped ZnO films for solar energy applications, in purview of the development of simple nanostructuring methodologies.

  5. Measurement of carbon capture efficiency and stored carbon leakage

    Science.gov (United States)

    Keeling, Ralph F.; Dubey, Manvendra K.

    2013-01-29

    Data representative of a measured carbon dioxide (CO.sub.2) concentration and of a measured oxygen (O.sub.2) concentration at a measurement location can be used to determine whether the measured carbon dioxide concentration at the measurement location is elevated relative to a baseline carbon dioxide concentration due to escape of carbon dioxide from a source associated with a carbon capture and storage process. Optionally, the data can be used to quantify a carbon dioxide concentration increase at the first location that is attributable to escape of carbon dioxide from the source and to calculate a rate of escape of carbon dioxide from the source by executing a model of gas-phase transport using at least the first carbon dioxide concentration increase. Related systems, methods, and articles of manufacture are also described.

  6. Soil carbon stocks decrease following conversion of secondary forests to rubber (Hevea brasiliensis) plantations.

    Science.gov (United States)

    de Blécourt, Marleen; Brumme, Rainer; Xu, Jianchu; Corre, Marife D; Veldkamp, Edzo

    2013-01-01

    Forest-to-rubber plantation conversion is an important land-use change in the tropical region, for which the impacts on soil carbon stocks have hardly been studied. In montane mainland southeast Asia, monoculture rubber plantations cover 1.5 million ha and the conversion from secondary forests to rubber plantations is predicted to cause a fourfold expansion by 2050. Our study, conducted in southern Yunnan province, China, aimed to quantify the changes in soil carbon stocks following the conversion from secondary forests to rubber plantations. We sampled 11 rubber plantations ranging in age from 5 to 46 years and seven secondary forest plots using a space-for-time substitution approach. We found that forest-to-rubber plantation conversion resulted in losses of soil carbon stocks by an average of 37.4±4.7 (SE) Mg C ha(-1) in the entire 1.2-m depth over a time period of 46 years, which was equal to 19.3±2.7% of the initial soil carbon stocks in the secondary forests. This decline in soil carbon stocks was much larger than differences between published aboveground carbon stocks of rubber plantations and secondary forests, which range from a loss of 18 Mg C ha(-1) to an increase of 8 Mg C ha(-1). In the topsoil, carbon stocks declined exponentially with years since deforestation and reached a steady state at around 20 years. Although the IPCC tier 1 method assumes that soil carbon changes from forest-to-rubber plantation conversions are zero, our findings show that they need to be included to avoid errors in estimating overall ecosystem carbon fluxes.

  7. Gas Phase Conversion of Carbon Tetrachloride to Alkyl Chlorides Catalyzed by Supported Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    SUN Aijun; ZHANG Jinlong; LI Chunxi; MENG Hong

    2009-01-01

    An efficient way of converting carbon tetrachloride(CTC)to alkyl chlorides is reported,which uses the catalysts of ionic liquids supported on granular active carbon.The catalytic performance was evaluated in a temperature range of 120-200℃ and atmospheric pressure for different ionic liquids,namely 1-butyl-3-methylimidazolium chloride,1-octyl-3-methylimidazolium chloride,hydrochloric salts of N-methylimidazole(MIm),pyridine and triethylamine,as well as bisulfate and dihydric phosphate of N-methylimidazole.On this basis,the reaction mechanism was proposed,and the influences of the reaction temperature and the attributes of ionic liquids were discussed.The overall reaction was assumed to be comprised of two steps,the hydrolysis of CTC and reaction of HCI with alcohols under acidic catalyst.The results indicate that the conversion of CTC increased monotonically with temperature and even approached 100% at 200 ℃,while the maximum selectivity to alkyl chlorides was obtained around 160 ℃.This reaction might be potentially applicable to the resource utilization of superfluous byproduct of CTC in the chloromethane industry.

  8. Cationic organobismuth complex as an effective catalyst for conversion of CO2 into cyclic carbonates

    Institute of Scientific and Technical Information of China (English)

    Xiaowen ZHANG; Weili DAI; Shuangfeng YIN; Shenglian LUO; Chak-Tong AU

    2009-01-01

    In order to achieve high-efficiency conversion of CO2 into valuable chemicals, and to exploit new appli-cations of organobismuth compounds, cationic organo-bismuth complex with 5,6,7,12-tetrahydrodibenz[c,f] [ 1,5 ]azabismocine framework was examined for the first time for the coupling of CO2 into cyclic carbonates, using ter-minal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions. It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO2 with a wide range of terminal epoxide. The selectivity of propylene carbonates could reach 100%, and the max-imum turnover frequency was up to 10740 h-1 at 120℃ and 3 MPa CO2 pressure when tetrabutylammonium iod-ide was used as co-catalyst. Moreover, the catalyst is environment friendly, resistant to air and water, and can be readily reused and recycled without any loss of activity,demonstrating a potential in industrial application.

  9. Efficient multicast routing in wavelength-division-multiplexing networks with light splitting and wavelength conversion

    Science.gov (United States)

    Zheng, Sheng; Tian, Jinwen; Liu, Jian

    2005-04-01

    We propose wavelength-division-multiplexing (WDM) networks with light splitting and wavelength conversion that can efficiently support multicast routing between nodes. Our iterative algorithm analyzes the original multicast routing network by decomposing it into multicast subgroups. These subgroups have the same wavelength, and the individual subgroup is combined to build a multicast tree. From the multicast tree, we can compute efficiently to multicast for short paths. Numerical results obtained for the ARPANET show that our algorithm can greatly reduce the optical blocking probability and the number of required wavelength conversions.

  10. Carbon conversion and metabolic rate in two marine sponges

    NARCIS (Netherlands)

    Koopmans, M.; Van Rijswijk, P.; Martens, D.; Egorova-Zachernyuk, T.A.; Middelburg, J.J.; Wijffels, R.H.

    2011-01-01

    The carbon metabolism of two marine sponges, Haliclona oculata and Dysidea avara, has been studied using a 13C isotope pulse-chase approach. The sponges were fed 13C-labeled diatoms (Skeletonema costatum) for 8 h and they took up between 75 and 85%. At different times, sponges were sampled for total

  11. Efficient and low-noise single-photon-level frequency conversion interfaces using silicon nanophotonics

    CERN Document Server

    Li, Qing; Srinivasan, Kartik

    2015-01-01

    Optical frequency conversion has applications ranging from tunable light sources to telecommunications-band interfaces for quantum information science. Here, we demonstrate efficient, low-noise frequency conversion on a nanophotonic chip through four-wave-mixing Bragg scattering in compact (footprint 60 % for the last two processes, a signal conversion bandwidth > 1 GHz, < 60 mW of continuous-wave pump power needed, and background noise levels between a few fW and a few pW, these devices are suitable for quantum frequency conversion of single photon states from InAs quantum dots. Simulations based on coupled mode equations and the Lugiato-Lefever equation are used to model device performance, and show quantitative agreement with measurements.

  12. Conversion of organic carbon in the decomposable organic wastes in anaerobic lysimeters under different temperatures

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The quantitative fractions of conversion of organic carbon in the decomposable organic wastes with initial moisture of 70% sorted from municipal solid wastes(MSW) in lysimeters into biogas, leachate and solid residue were characterized, under temperatures of 25, 30 and 41℃, respectively, and circulation of leachate generated within the lysimeters. It is found that 27% of organic carbon in the wastes are conversed into gases, 0.8% into leachate, and the other 72% remained in the decomposable solid residues, after 180 days' degradation at 41℃. Higher temperature will lead to more rapid degradation and result to higher conversion of the organic carbon to biogas and lower to both solid residues and leachate, while the pollutant concentrations in leachate will be lower at a higher temperature and the values of COD are quite consistent with TOC.

  13. Conversion of organic carbon in the decomposable organic wastes in anaerobic lysimeters under different temperatures.

    Science.gov (United States)

    Zhao, You-Cai; Wang, Luo-Chun

    2003-05-01

    The quantitative fractions of conversion of organic carbon in the decomposable organic wastes with initial moisture of 70% sorted from municipal solid wastes (MSW) in lysimeters into biogas, leachate and solid residue were characterized, under temperatures of 25, 30 and 41 degrees C, respectively, and circulation of leachate generated within the lysimeter. It is found that 27% of organic carbon in the wastes are conversed into gases, 0.8% into leachate, and the other 72% remained in the decomposable solid residues, after 180 days' degradation at 41 degrees C. Higher temperature will lead to more rapid degradation and result to higher conversion of the organic carbon to biogas and lower to both solid residues and leachate, while the pollutant concentrations in leachate will be lower at a higher temperature and the values of COD are quite consistent with TOC. PMID:12938979

  14. Supercritical Carbon Dioxide Brayton Cycle Energy Conversion System

    International Nuclear Information System (INIS)

    This report contains the description of the S-CO2 Brayton cycle coupled to KALIMER-600 as an alternative energy conversion system. For system development, a computer code was developed to calculate heat balance of 100% power operation condition. Based on the computer code, the S-CO2 Brayton cycle energy conversion system was constructed for the KALIMER-600. Using the developed turbomachinery models, the off-design characteristics and the sensitivities of the S-CO2 turbomachinery were investigated. For the development of PCHE models, a one-dimensional analysis computer code was developed to evaluate the performance of the PCHE. Possible control schemes for power control in the KALIMER-600 S-CO2 Brayton cycle were investigated by using the MARS code. Simple power reduction and recovery event was selected and analyzed for the transient calculation. For the evaluation of Na/CO2 boundary failure event, a computer was developed to simulate the complex thermodynamic behaviors coupled with the chemical reaction between liquid sodium and CO2 gas. The long term behavior of a Na/CO2 boundary failure event and its consequences which lead to a system pressure transient were evaluated

  15. Supercritical Carbon Dioxide Brayton Cycle Energy Conversion System

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jae Eun; Kim, S. O.; Seong, S. H.; Eoh, J. H.; Lee, T. H.; Choi, S. K.; Han, J. W.; Bae, S. W

    2007-12-15

    This report contains the description of the S-CO{sub 2} Brayton cycle coupled to KALIMER-600 as an alternative energy conversion system. For system development, a computer code was developed to calculate heat balance of 100% power operation condition. Based on the computer code, the S-CO{sub 2} Brayton cycle energy conversion system was constructed for the KALIMER-600. Using the developed turbomachinery models, the off-design characteristics and the sensitivities of the S-CO{sub 2} turbomachinery were investigated. For the development of PCHE models, a one-dimensional analysis computer code was developed to evaluate the performance of the PCHE. Possible control schemes for power control in the KALIMER-600 S-CO{sub 2} Brayton cycle were investigated by using the MARS code. Simple power reduction and recovery event was selected and analyzed for the transient calculation. For the evaluation of Na/CO{sub 2} boundary failure event, a computer was developed to simulate the complex thermodynamic behaviors coupled with the chemical reaction between liquid sodium and CO{sub 2} gas. The long term behavior of a Na/CO{sub 2} boundary failure event and its consequences which lead to a system pressure transient were evaluated.

  16. Tunable Second Harmonic Generation with High Conversion Efficiency in Periodically Poled Lithium Niobate Channel Waveguide

    Institute of Scientific and Technical Information of China (English)

    XU Rong-hui; CHEN Xian-feng; CHEN Yu-ping; YE Zhi-qing; XIA Yu-xing

    2007-01-01

    The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported.The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications.The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc2 shape.The peak of SHG conversion efficiency was 75% · W-1 · cm-2 as well as reported. The relationship between the center fundamental wavelength and tempera ture shows that SHG can be effectively tuned by the temperature in PPLN waveguide.

  17. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    International Nuclear Information System (INIS)

    We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals

  18. Thermodynamics and energy conversion of near-field thermal radiation: Maximum work and efficiency bounds

    Directory of Open Access Journals (Sweden)

    Latella Ivan

    2014-01-01

    Full Text Available We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.

  19. Thermodynamics and energy conversion of near-field thermal radiation: maximum work and efficiency bounds

    OpenAIRE

    Latella Ivan; Pérez-Madrid Agustín; Rubi J. Miguel

    2015-01-01

    We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.

  20. A power-efficient ultra-wideband pulse generator based on multiple PM-IM conversions

    OpenAIRE

    Lui, KS; Wong, KKY; Zhou, E.; Xu, X.

    2010-01-01

    A novel photonic generation of power-efficient ultra-wideband (UWB) pulse by incoherent summation of two asymmetric monocycle pulses with inverted polarities is experimentally demonstrated. The principles of multiple cross-phase modulations in a highly nonlinear fiber and multiple phase modulation to intensity modulation conversions in a commercially available arrayed-waveguide grating are used. The combined UWB pulse exploiting spectral efficiency of 50.59% in experiment is fully compliant w...

  1. Monocrystalline silicon photovoltaic luminescent solar concentratorr with 4.2% power conversion efficiency

    NARCIS (Netherlands)

    Desmet, L.; Ras, A.J.M.; De Boer, D.K.G.; Debije, M.G.

    2012-01-01

    We report conversion efficiencies of experimental single and dual lightguide luminescent solar concentrators. We have built several 5x5cm2 and 10x10 cm2 LSC demonstrators, consisting of c-Si photovoltaiccells attached to luminescent lightguides of Lumogen F Red 305 dyeand perylene perinone dye. The

  2. Patchy zooplankton grazing and high energy conversion efficiency: ecological implications of sandeel behavior and strategy

    DEFF Research Database (Denmark)

    Deurs, Mikael van; Christensen, Asbjørn; Rindorf, Anna

    2013-01-01

    of prey. Here we studied zooplankton consumption and energy conversion efficiency of lesser sandeel (Ammodytes marinus) in the central North Sea, using stomach data, length and weight-at-age data, bioenergetics, and hydrodynamic modeling. The results suggested: (i) Lesser sandeel in the Dogger area depend...... sandeel densities and growth rates per area than larger habitats...

  3. Effect of end reflections on conversion efficiency of coaxial relativistic backward wave oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Yan; Chen, Changhua; Sun, Jun; Shi, Yanchao; Ye, Hu; Wu, Ping; Li, Shuang; Xiong, Xiaolong [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2015-11-07

    This paper theoretically investigates the effect of end reflections on the operation of the coaxial relativistic backward wave oscillator (CRBWO). It is found that the considerable enhancement of the end reflection at one end increases the conversion efficiency, but excessively large end reflections at both ends weaken the asynchronous wave-beam interaction and thus reduce the conversion efficiency. Perfect reflection at the post end significantly improves the interaction between the electron beam and the asynchronous harmonic so that the conversion efficiency is notably increased. Based on the theoretical research, the diffraction-CRBWO with the generated microwave diffracted and output through the front end of the coaxial slow wave structure cavity is proposed. The post end is conductively closed to provide the perfect reflection. This promotes the amplitude and uniformity of the longitudinal electric field on the beam transmission line and improves the asynchronous wave-beam interaction. In numerical simulations under the diode voltage and current of 450 kV and 5.84 kA, microwave generation with the power of 1.45 GW and the conversion efficiency of 55% are obtained at the frequency of 7.45 GHz.

  4. Effect of end reflections on conversion efficiency of coaxial relativistic backward wave oscillator

    Science.gov (United States)

    Teng, Yan; Chen, Changhua; Sun, Jun; Shi, Yanchao; Ye, Hu; Wu, Ping; Li, Shuang; Xiong, Xiaolong

    2015-11-01

    This paper theoretically investigates the effect of end reflections on the operation of the coaxial relativistic backward wave oscillator (CRBWO). It is found that the considerable enhancement of the end reflection at one end increases the conversion efficiency, but excessively large end reflections at both ends weaken the asynchronous wave-beam interaction and thus reduce the conversion efficiency. Perfect reflection at the post end significantly improves the interaction between the electron beam and the asynchronous harmonic so that the conversion efficiency is notably increased. Based on the theoretical research, the diffraction-CRBWO with the generated microwave diffracted and output through the front end of the coaxial slow wave structure cavity is proposed. The post end is conductively closed to provide the perfect reflection. This promotes the amplitude and uniformity of the longitudinal electric field on the beam transmission line and improves the asynchronous wave-beam interaction. In numerical simulations under the diode voltage and current of 450 kV and 5.84 kA, microwave generation with the power of 1.45 GW and the conversion efficiency of 55% are obtained at the frequency of 7.45 GHz.

  5. A Study of Energy Conversion Efficiency Versus Plasma Density by Lower Hybrid Current Drive in HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    丁伯江; 匡光力; 刘岳修; 刘登成; 单家方; 刘甫坤; 沈慰慈; 石跃江; 吴振伟; 林建安; 俞家文; 徐汉东; 商连全; 张晓东; 刘小宁; 赵燕平; 李建刚

    2002-01-01

    Ramp-up experiments by means of lower hybrid wave on HT-7 superconducting tokamak have been performed and analyzed. A ramp-up rate of over 300 kA/s is obtained and a conversion efficiency of over 10% has been achieved during the ramp-up phase. The study of the dependence of conversion efficiency on plasma density shows that the conversion efficiency is affected by the driven current, which is mainly dominated by the competition of impurity concentration with wave accessibility condition. In addition, the effect of current profile may play an important role in determining the conversion efficiency.

  6. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  7. 14.7% efficient mesoscopic perovskite solar cells using single walled carbon nanotubes/carbon composite counter electrodes

    Science.gov (United States)

    Li, Hao; Cao, Kun; Cui, Jin; Liu, Shuangshuang; Qiao, Xianfeng; Shen, Yan; Wang, Mingkui

    2016-03-01

    A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive.A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07347b

  8. Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings.

    Science.gov (United States)

    Zahran, Zaki N; Mohamed, Eman A; Naruta, Yoshinori

    2016-01-01

    Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe-containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push-pull mechanism. Bio-inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe-Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe-Fe separation distance. PMID:27087483

  9. Bio-inspired cofacial Fe porphyrin dimers for efficient electrocatalytic CO2 to CO conversion: Overpotential tuning by substituents at the porphyrin rings

    Science.gov (United States)

    Zahran, Zaki N.; Mohamed, Eman A.; Naruta, Yoshinori

    2016-04-01

    Efficient reduction of CO2 into useful carbon resources particularly CO is an essential reaction for developing alternate sources of fuels and for reducing the greenhouse effect of CO2. The binuclear Ni, Fe‑containing carbon monoxide dehydrogenase (CODHs) efficiently catalyzes the reduction of CO2 to CO. The location of Ni and Fe at proper positions allows their cooperation for CO2 to CO conversion through a push‑pull mechanism. Bio‑inspired from CODHs, we used several cofacial porphyrin dimers with different substituents as suitable ligands for holding two Fe ions with suitable Fe‑Fe separation distance to efficiently and selectively promote CO2 to CO conversion with high turnover frequencies, TOFs. The substituents on the porphyrin rings greatly affect the catalysis process. By introducing electron-withdrawing/-donating groups, e.g. electron-withdrawing perfluorophenyl, at all meso positions of the porphyrin rings, the catalysis overpotential, η was minimized by ≈0.3 V compared to that obtained by introducing electron-donating mesityl groups. The Fe porphyrin dimers among reported catalysts are the most efficient ones for CO2 to CO conversion. Control experiments indicate that the high performance of the current CO2 to CO conversion catalysts is due to the presence of binuclear Fe centers at suitable Fe‑Fe separation distance.

  10. DBD in burst mode: solution for more efficient CO2 conversion?

    CERN Document Server

    Ozkan, A; Silva, T; Britun, N; Snyders, R; Reniers, F; Bogaerts, A

    2016-01-01

    CO2 conversion into value-added products has gained significant interest over the few last years, as the greenhouse gas concentrations constantly increase due to anthropogenic activities. Here we report on experiments for CO2 conversion by means of a cold atmospheric plasma using a cylindrical flowing dielectric barrier discharge (DBD) reactor. A detailed comparison of this DBD ignited in a so-called burst mode (i.e. where an AC voltage is applied during a limited amount of time) and pure AC mode is carried out to evaluate their effect on the conversion of CO2 as well as on the energy efficiency. Decreasing the duty cycle in the burst mode from 100% (i.e. corresponding to pure AC mode) to 40% leads to a rise in the conversion from 16--26% and to a rise in the energy efficiency from 15 to 23%. Based on a detailed electrical analysis, we show that the conversion correlates with the features of the microfilaments. Moreover, the root-mean-square voltage in the burst mode remains constant as a function of the proc...

  11. Carbon conversion and metabolic rate in two marine sponges.

    Science.gov (United States)

    Koopmans, M; van Rijswijk, P; Martens, D; Egorova-Zachernyuk, T A; Middelburg, J J; Wijffels, R H

    2011-01-01

    The carbon metabolism of two marine sponges, Haliclona oculata and Dysidea avara, has been studied using a (13)C isotope pulse-chase approach. The sponges were fed (13)C-labeled diatoms (Skeletonema costatum) for 8 h and they took up between 75 and 85%. At different times, sponges were sampled for total (13)C enrichment, and fatty acid (FA) composition and (13)C enrichment. Algal biomarkers present in the sponges were highly labeled after feeding but their labeling levels decreased until none was left 10 days after enrichment. The sponge-specific FAs incorporated (13)C label already during the first day and the amount of (13)C label inside these FAs kept increasing until 3 weeks after labeling. The algal-derived carbon captured by the sponges during the 8-h feeding period was thus partly respired and partly metabolized during the weeks following. Apparently, sponges are able to capture enough food during short periods to sustain longer-term metabolism. The change of carbon metabolic rate of fatty acid synthesis due to mechanical damage of sponge tissue was studied by feeding sponges with (13)C isotope-labeled diatom (Pheaodactylum tricornutum) either after or before damaging and tracing back the (13)C content in the damaged and healthy tissue. The filtration and respiration in both sponges responded quickly to damage. The rate of respiration in H. oculata reduced immediately after damage, but returned to its initial level after 6 h. The (13)C data revealed that H. oculata has a higher metabolic rate in the tips where growth occurs compared to the rest of the tissue and that the metabolic rate is increased after damage of the tissue. For D. avara, no differences were found between damaged and non-damaged tissue. However, the filtration rate decreased directly after damage. PMID:24489407

  12. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans

    NARCIS (Netherlands)

    Henstra, A.M.; Stams, A.J.M.

    2011-01-01

    Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial cat

  13. How will conversion to organic cereal production affect carbon stocks in Swedish agricultural soils?

    OpenAIRE

    Andrén, Olof; Kätterer, Thomas; Kirchmann, Holger

    2008-01-01

    Soil carbon changes were modelled over 30 years with the focus on cereal crops, since leys are often managed similarly in organic and conventional agriculture. Other crops were not considered due to difficulties in large-scale cropping of oilseed rape and potatoes organically because of pest problems. Four scenarios were used: 0%, 8% (current), 20% and 100% organic cereal production. Conversion to organic cereal crop production was found to reduce the amount of carbon stored as organic matter...

  14. Phase conversion in silicon and carbon nanomaterials at extreme pressure

    Science.gov (United States)

    Crane, Matthew; Smith, Bennett; Abramson, Evan; Pauzauskie, Peter

    The high pressures and temperatures accessible in laser-heated diamond anvil cells (LH-DAC) have produced fundamental insights by identifying metastable states with extraordinary properties. However, the actual conditions necessary to access a metastable state depend on the kinetics of phase transformation. The explosion of research in nanomaterials has generated interest in exploring how phase transformations occur in materials with high radii of curvature, and how we can leverage these effects. We present work investigating phase transformations in Si- and C-based nanomaterials with high radii of curvature. We have loaded a LH-DAC with Si nanowires (NWs) and examined the phase at a range of pressures to discover a recoverable phase transition to a wurtzite crystal structure. For C materials, we have synthesized a pyrolyzed carbon aerogel, an amorphous carbon sol gel with size features of ~10 nm and incredibly low density and thermal conductivity (~10-2 W/m-K). We investigate spatial resolution of heating under pressure and the effect of temperature on resulting material electronic structure. Finally, we model heating with Mie theory to provide insights into the phase transformations of nanomaterials.

  15. 76 FR 6488 - Notice of Submission of Proposed Information Collection to OMB Conversion of Efficiency Units to...

    Science.gov (United States)

    2011-02-04

    ... URBAN DEVELOPMENT Notice of Submission of Proposed Information Collection to OMB Conversion of... and forms to permit the conversion of efficiencies to one-bedrooms provided it can be demonstrated that the conversion is warranted by local demands and results in the long- term financial and...

  16. Environmentally Printing Efficient Organic Tandem Solar Cells with High Fill Factors: A Guideline Towards 20% Power Conversion Efficiency

    DEFF Research Database (Denmark)

    Li, Ning; Baran, Derya; Spyropoulos, George D.;

    2014-01-01

    to enhance the power conversion efficiency (PCE). However, due to the undeveloped deposition techniques, the challenges in ink formulation as well as the lack of commercially available high performance active materials, roll-to-roll fabrication of highly efficient organic tandem solar cells currently...... presents a major challenge. The reported high PCE values from lab-scale spin-coated devices are, of course, representative, but not helpful for commercialization. Here, organic tandem solar cells with exceptionally high fill factors and PCE values of 7.66% (on glass) and 5.56% (on flexible substrate...

  17. Toward High-Power Klystrons With RF Power Conversion Efficiency on the Order of 90%

    CERN Document Server

    Baikov, Andrey Yu; Syratchev, Igor

    2015-01-01

    The increase in efficiency of RF power generation for future large accelerators is considered a high priority issue. The vast majority of the existing commercial high-power RF klystrons operates in the electronic efficiency range between 40% and 55%. Only a few klystrons available on the market are capable of operating with 65% efficiency or above. In this paper, a new method to achieve 90% RF power conversion efficiency in a klystron amplifier is presented. The essential part of this method is a new bunching technique - bunching with bunch core oscillations. Computer simulations confirm that the RF production efficiency above 90% can be reached with this new bunching method. The results of a preliminary study of an L-band, 20-MW peak RF power multibeam klystron for Compact Linear Collider with the efficiency above 85% are presented.

  18. Efficient mode conversion in an optical nanoantenna mediated by quantum emitters

    CERN Document Server

    Straubel, Jakob; Rockstuhl, Carsten; Slowik, Karolina

    2016-01-01

    Converting signals between different electromagnetic modes is an asset for future information technologies. In general, slightly asymmetric optical nanoantennas enable the coupling between bright and dark modes sustained by an optical nanoantenna. However, the conversion efficiency might be very low. Here, we show that the additional incorporation of a quantum emitter allows to tremendously enhance this efficiency. The enhanced local density of states cycles the quantum emitter between its upper and lower level at an extremely hight rate; hence converting the energy very efficient. The process is robust with respect to possible experimental tolerances and adds a new ingredient to be exploited while studying and applying coupling phenomena in optical nanosystems.

  19. Characterization of the major reactions during conversion of lignin to carbon fiber

    Directory of Open Access Journals (Sweden)

    Hendrik Mainka

    2015-10-01

    Full Text Available Lightweight design is an essential part of the overall Volkswagen strategy for reducing the CO2 emissions. The use of carbon fiber offers an enormous lightweight potential. In comparison to steel enabling a mass reduction of up to 70% in automotive parts without a degradation of the functionalities is possible. Today, the use of carbon fiber is limited in mass series applications of the automotive industry by the cost of the conventional C-fiber precursor polyacrylonitrile (PAN. 50% of the cost of a conventional carbon fiber already belongs to the cost of the PAN precursor. Lignin as a precursor for carbon fiber production can realize enormous savings in cost. For qualifying lignin-based carbon fiber for automotive mass production a detailed characterization of this new material is necessary. Therefore, nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy are used. Using the results of these experiments, the major reactions during conversion of lignin to carbon fiber are proposed.

  20. Long-term shifts in life-cycle energy efficiency and carbon intensity.

    Science.gov (United States)

    Yeh, Sonia; Mishra, Gouri Shankar; Morrison, Geoff; Teter, Jacob; Quiceno, Raul; Gillingham, Kenneth; Riera-Palou, Xavier

    2013-03-19

    The quantity of primary energy needed to support global human activity is in large part determined by how efficiently that energy is converted to a useful form. We estimate the system-level life-cycle energy efficiency (EF) and carbon intensity (CI) across primary resources for 2005-2100. Our results underscore that although technological improvements at each energy conversion process will improve technology efficiency and lead to important reductions in primary energy use, market mediated effects and structural shifts toward less efficient pathways and pathways with multiple stages of conversion will dampen these efficiency gains. System-level life-cycle efficiency may decrease as mitigation efforts intensify, since low-efficiency renewable systems with high output have much lower GHG emissions than some high-efficiency fossil fuel systems. Climate policies accelerate both improvements in EF and the adoption of renewable technologies, resulting in considerably lower primary energy demand and GHG emissions. Life-cycle EF and CI of useful energy provide a useful metric for understanding dynamics of implementing climate policies. The approaches developed here reiterate the necessity of a combination of policies that target efficiency and decarbonized energy technologies. We also examine life-cycle exergy efficiency (ExF) and find that nearly all of the qualitative results hold regardless of whether we use ExF or EF. PMID:23409918

  1. Changes in organic carbon stocks upon land use conversion in the Brazilian Cerrado: A review. Agriculture

    NARCIS (Netherlands)

    Batlle-Bayer, L.; Batjes, N.H.; Bindraban, P.S.

    2010-01-01

    This paper reviews current knowledge on changes in carbon stocks upon land use conversion in the Brazilian Cerrado. First, we briefly characterize the savanna ecosystem and summarize the main published data on C stocks under natural conditions. The effects of increased land use pressure in the Cerra

  2. Large-scale cauliflower-shaped hierarchical copper nanostructures for efficient photothermal conversion.

    Science.gov (United States)

    Fan, Peixun; Wu, Hui; Zhong, Minlin; Zhang, Hongjun; Bai, Benfeng; Jin, Guofan

    2016-08-14

    Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent heating up effect under the sunlight illumination. In the experiment of evaporating water, the structured surface yields an overall photothermal conversion efficiency over 60% under an illuminating solar power density of ∼1 kW m(-2). The presented technology provides a cost-effective, reliable, and simple way for realizing broadband omnidirectional light absorptive metal surfaces for efficient solar energy harvesting and utilization, which is highly demanded in various light harvesting, anti-reflection, and photothermal conversion applications. Since the structure is directly formed by femtosecond laser writing, it is quite suitable for mass production and can be easily extended to a large surface area. PMID:27430171

  3. New Architecture towards Ultrathin CdTe Solar Cells for High Conversion Efficiency

    Directory of Open Access Journals (Sweden)

    A. Teyou Ngoupo

    2015-01-01

    Full Text Available Solar Cell Capacitance Simulator in 1 Dimension (SCAPS-1D is used to investigate the possibility of realizing ultrathin CdTe based solar cells with high and stable conversion efficiency. In the first step, we modified the conventional cell structure by substituting the CdS window layer with a CdS:O film having a wide band gap ranging from 2.42 to 3.17 eV. Thereafter, we simulated the quantum efficiency, as well as the parameters of J-V characteristics, and showed how the thickness of CdS:O layer influences output parameters of Glass/SnO2/ZTO/CdS:O/CdTe1-xSx/CdTe/Ni reference cell. High conversion efficiency of 17.30% has been found using CdTe1-xSx (x=0.12 and CdTe layers of thickness 15 nm and 4 μm, respectively. Secondly, we introduced a BSR layer between the absorber layer and back metal contact, which led to Glass/SnO2/ZTO/CdS:O/CdTe1-xSx/CdTe/BSR/Ni configuration. We found that a few nanometers (about 5 nm of CdTe1-xSx layer is sufficient to obtain high conversion efficiency. For BSR layer, different materials with large band gap, such as ZnTe, Cu2Te, and p+-CdTe, have been used in order to reduce minority carrier recombination at the back contact. When ZnTe is used, high conversion efficiency of 21.65% and better stability are obtained, compared to other BSR.

  4. Evaluation of conversion efficiency of light to hydrogen energy by Anabaena variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jong Hyun; Hae Shin, Ji; Park, Tai Hyun [School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Mi-Sun [Biomass Research Team, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of); Jun Sim, Sang [Department of Chemical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2006-05-15

    Cyanobacteria provide an efficient system for producing H{sub 2} from water using solar energy. The energy conversion efficiency can be defined by the ratio of H{sub 2} produced to the light energy absorbed. An IR and opalescent plate method was used to measure the light energy absorbed. Since cyanobacteria absorb light in the visible range but not in the infrared range, the net amount of light energy absorbed by the cells can be estimated by measuring the IR and visible light intensities transmitted through the biochamber. A rectangular biochamber was used for measuring the conversion efficiency from light energy to H{sub 2} energy. A quantum meter and radiometer were used to measure the light intensity transmitted through the chamber. Anabaena variabilis was cultured in a BG11 medium with 3.6mM NaNO{sub 3} and the light intensity was 40-50{mu}mol/m{sup 2}/s in the growth phase and 120-140{mu}mol/m{sup 2}/s in the H{sub 2} production phase. The maximum H{sub 2} production was 50ml for 40h and cell density was 1.2g/l. The H{sub 2} production rate was 4.1ml H{sub 2}/g dry cell weight/h. Based on the light absorbed in the H{sub 2} production phase, the energy conversion efficiency from light to H{sub 2} was 1.5% on average and 3.9% at the maximum. Based on the light energy absorbed in the cell growth and H{sub 2} production phases, the energy conversion efficiency was 1.1% on average. (author)

  5. Conversion efficiency limits and bandgap designs for multi-junction solar cells with internal radiative efficiencies below unity.

    Science.gov (United States)

    Zhu, Lin; Mochizuki, Toshimitsu; Yoshita, Masahiro; Chen, Shaoqiang; Kim, Changsu; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-05-16

    We calculated the conversion-efficiency limit ηsc and the optimized subcell bandgap energies of 1 to 5 junction solar cells without and with intermediate reflectors under 1-sun AM1.5G and 1000-sun AM1.5D irradiations, particularly including the impact of internal radiative efficiency (ηint) below unity for realistic subcell materials on the basis of an extended detailed-balance theory. We found that the conversion-efficiency limit ηsc significantly drops when the geometric mean ηint* of all subcell ηint in the stack reduces from 1 to 0.1, and that ηsc degrades linearly to logηint* for ηint* below 0.1. For ηint*<0.1 differences in ηsc due to additional intermediate reflectors became very small if all subcells are optically thick for sun light. We obtained characteristic optimized bandgap energies, which reflect both ηint* decrease and AM1.5 spectral gaps. These results provide realistic efficiency targets and design principles.

  6. Conversion efficiency limits and bandgap designs for multi-junction solar cells with internal radiative efficiencies below unity.

    Science.gov (United States)

    Zhu, Lin; Mochizuki, Toshimitsu; Yoshita, Masahiro; Chen, Shaoqiang; Kim, Changsu; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-05-16

    We calculated the conversion-efficiency limit ηsc and the optimized subcell bandgap energies of 1 to 5 junction solar cells without and with intermediate reflectors under 1-sun AM1.5G and 1000-sun AM1.5D irradiations, particularly including the impact of internal radiative efficiency (ηint) below unity for realistic subcell materials on the basis of an extended detailed-balance theory. We found that the conversion-efficiency limit ηsc significantly drops when the geometric mean ηint* of all subcell ηint in the stack reduces from 1 to 0.1, and that ηsc degrades linearly to logηint* for ηint* below 0.1. For ηint*<0.1 differences in ηsc due to additional intermediate reflectors became very small if all subcells are optically thick for sun light. We obtained characteristic optimized bandgap energies, which reflect both ηint* decrease and AM1.5 spectral gaps. These results provide realistic efficiency targets and design principles. PMID:27409948

  7. Enhanced conversion efficiency in perovskite solar cells by effectively utilizing near infrared light.

    Science.gov (United States)

    Que, Meidan; Que, Wenxiu; Yin, Xingtian; Chen, Peng; Yang, Yawei; Hu, Jiaxing; Yu, Boyan; Du, Yaping

    2016-08-14

    Up-conversion β-NaYF4:Yb(3+),Tm(3+)/NaYF4 core-shell nanoparticles (NYF NPs) with a high luminous intensity in the visible light region were synthesized by a hydrothermal reaction process. Photocurrent densities of the mesoscopic perovskite solar cells fabricated by incorporating up-conversion NYF NPs into the electron transporting layer are effectively enhanced. The effects of the thicknesses of the electron transporting layer and the weight ratio of up-conversion NYF NPs/TiO2 on the power conversion efficiency (PCE) of the as-fabricated devices were also investigated. The results indicate that the PCE of the optimized device achieves 16.9%, which is 20% higher than that of the device without introducing NYF NPs, and the steady-state PCE of the as-fabricated devices is close to its transient-state PCE. The up-conversion effect of NYF NPs is conducive to higher device performance rather than the nanoparticles as scattering centers to increase possible light absorption of the perovskite film or the electronic effect of the NaYF4 shell surface. These results can be further confirmed by finite-difference time-domain simulation. Photoluminescence results suggest that the multiphonon-assistance can accelerate the nonradiative recombination process at a lower temperature. Incorporating NYF NPs into the electron transporting layer opens a new approach to a promising family of electron transporting materials for mesoscopic perovskite solar cells. PMID:27406678

  8. Efficiency enhancement of stationary solar energy based power conversion systems in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Sharan, Anand M. [Faculty of Engineering, Memorial University of Newfoundland, St. John' s, Newfoundland (Canada)

    2009-09-15

    This paper presents the optimum energy conversion conditions of stationary photovoltaic panels used for electrical power generation. The results are arrived at after performing calculations for 180 days in a given year at the latitude of St. John's, Newfoundland. The latitude of this city is close to other Canadian major population centers. Various angular orientations of sun's rays on the earth are considered. On a given day, the incident energy flux of sun is resolved into three components, and the conversion efficiency is based on the flux normal to the panels. The efficiency of conversion of the incident energy is measured with respect to a solar tracking process. The numbers of days in a given year are divided into two groups - one between the winter solstice and the spring equinox, and another between the spring equinox and the summer solstice. The results show the existence of two maxima, one for each of the two periods. By setting the panels at each of these maxima, very significant improvement in energy conversion can be achieved. (author)

  9. Efficient and high speed depth-based 2D to 3D video conversion

    Science.gov (United States)

    Somaiya, Amisha Himanshu; Kulkarni, Ramesh K.

    2013-09-01

    Stereoscopic video is the new era in video viewing and has wide applications such as medicine, satellite imaging and 3D Television. Such stereo content can be generated directly using S3D cameras. However, this approach requires expensive setup and hence converting monoscopic content to S3D becomes a viable approach. This paper proposes a depth-based algorithm for monoscopic to stereoscopic video conversion by using the y axis co-ordinates of the bottom-most pixels of foreground objects. This code can be used for arbitrary videos without prior database training. It does not face the limitations of single monocular depth cues nor does it combine depth cues, thus consuming less processing time without affecting the efficiency of the 3D video output. The algorithm, though not comparable to real-time, is faster than the other available 2D to 3D video conversion techniques in the average ratio of 1:8 to 1:20, essentially qualifying as high-speed. It is an automatic conversion scheme, hence directly gives the 3D video output without human intervention and with the above mentioned features becomes an ideal choice for efficient monoscopic to stereoscopic video conversion. [Figure not available: see fulltext.

  10. Carbon membranes for efficient water-ethanol separation

    CERN Document Server

    Gravelle, Simon; Joly, Laurent; Ybert, Christophe; Bocquet, Lydéric

    2016-01-01

    We demonstrate, on the basis of molecular dynamics simulations, the possibility of an efficient water-ethanol separation using nanoporous carbon membranes, namely carbon nanotube membranes, nanoporous graphene sheets, and multilayer graphene membranes. While these carbon membranes are in general permeable to both pure liquids, they exhibit a counter-intuitive "self-semi-permeability" to water in the presence of water-ethanol mixtures. This originates in a preferred ethanol adsorption in nanoconfinement that prevents water molecules from entering the carbon nanopores. An osmotic pressure is accordingly expressed across the carbon membranes for the water-ethanol mixture, which agrees with the classic van't Hoff type expression. This suggests a robust and versatile membrane-based separation, built on a pressure-driven reverse-osmosis process across these carbon-based membranes. In particular, the recent development of large-scale 'graphene-oxide' like membranes then opens an avenue for a versatile and efficient ...

  11. The effects of prey species on food conversion efficiency and growth of an insectivorous lizard.

    Science.gov (United States)

    Rich, C Nelson; Talent, Larry G

    2008-05-01

    Little is known about the effects of different prey species on lizard growth. We conducted a 6-week study to determine the relative effects of prey species on growth parameters of hatchling western fence lizards, Sceloporus occidentalis. Lizards were fed house cricket nymphs, Acheta domesticus, or mealworm larvae, Tenebrio molitor. The effects of prey species on growth were determined by measuring prey consumption, gross conversion efficiency of food [gain in mass (g)/food consumed (g)], gain in mass, and gain in snout-vent length. Lizards grew well on both the prey species. However, lizards that fed on crickets consumed a significantly higher percentage of their body mass per day than those fed mealworms. Nevertheless, lizards that consumed mealworms ingested significantly more metabolizable energy, had significantly higher food conversion efficiencies, significantly higher daily gains in mass, and significantly greater total growth in mass than lizards that fed on crickets. PMID:19360616

  12. A High Efficiency Wavelength Conversion Scheme Based on Four Wave Minxing in a Semiconductor Optical Amplifier

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new approach of all optical wavelength converter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) with the conjugate wave reflected by a fiber Bragg grating (FBG) and then amplified by the SOA is reported. By adjusting the pump power, the conversion efficiency could be improved 7~10dB with signal-to-background-noise-ratio (SBR) deteriorated 1~2dB, compared with traditional single pump four wave mixing.

  13. New Architecture towards Ultrathin CdTe Solar Cells for High Conversion Efficiency

    OpenAIRE

    A. Teyou Ngoupo; Ouédraogo, S.; Zougmoré, F.; Ndjaka, J. M. B.

    2015-01-01

    Solar Cell Capacitance Simulator in 1 Dimension (SCAPS-1D) is used to investigate the possibility of realizing ultrathin CdTe based solar cells with high and stable conversion efficiency. In the first step, we modified the conventional cell structure by substituting the CdS window layer with a CdS:O film having a wide band gap ranging from 2.42 to 3.17 eV. Thereafter, we simulated the quantum efficiency, as well as the parameters of J-V characteristics, and showed how the thickness of CdS:O l...

  14. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    Energy Technology Data Exchange (ETDEWEB)

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1997-12-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle vs. wavelength to second order, we efficiently doubled tunable fundamental light near 660 nm over a range of 80 nm using a 4-mm-long type-I {beta}-Barium Borate (BBO) crystal. Another lossless set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%.

  15. Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

    KAUST Repository

    Li, Yanbo

    2013-10-03

    Spurred by the decreased availability of fossil fuels and global warming, the idea of converting solar energy into clean fuels has been widely recognized. Hydrogen produced by photoelectrochemical water splitting using sunlight could provide a carbon dioxide lean fuel as an alternative to fossil fuels. A major challenge in photoelectrochemical water splitting is to develop an efficient photoanode that can stably oxidize water into oxygen. Here we report an efficient and stable photoanode that couples an active barium-doped tantalum nitride nanostructure with a stable cobalt phosphate co-catalyst. The effect of barium doping on the photoelectrochemical activity of the photoanode is investigated. The photoanode yields a maximum solar energy conversion efficiency of 1.5%, which is more than three times higher than that of state-of-the-art single-photon photoanodes. Further, stoichiometric oxygen and hydrogen are stably produced on the photoanode and the counter electrode with Faraday efficiency of almost unity for 100 min. © 2013 Macmillan Publishers Limited. All rights reserved.

  16. Efficient Direct Solar-to-Hydrogen Conversion by In Situ Interface Transformation of a Tandem Structure

    OpenAIRE

    May, Matthias M.; Lewerenz, Hans-Joachim; Lackner, David; Dimroth, Frank; Hannappel, Thomas

    2015-01-01

    Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilises customised tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here, a combined che...

  17. Efficiently Dispersing Carbon Nanotubes in Polyphenylene Sulfide

    OpenAIRE

    Sommer, Kevin M; Pipes, R. Byron

    2013-01-01

    Thermal plastics are replacing conventional metals in the aerospace, sporting, electronics, and other industries. Thermal plastics are able to withstand relatively high temperatures, have good fatigue properties, and are lighter than metals. Unfortunately, they are not very electrically conductive. However, adding carbon nanotubes to thermal plastics such as polyphenylene sulfide (PPS) can drastically increase the plastic's conductivity at a low weight percent of nanotubes called the percolat...

  18. Performance and fuel conversion efficiency of a spark ignition engine fueled with iso-butanol

    International Nuclear Information System (INIS)

    Highlights: ► Iso-butanol use in a port injection spark ignition engine. ► Fuel conversion efficiency calculated based on chassis dynamometer measurements. ► Combined study of engine efficiency and air–fuel mixture temperature. ► Excellent running characteristics with minor fuel system modifications. ► Up to 11% relative drop in part load efficiency due to incomplete fuel vaporization. -- Abstract: Alcohols are increasingly used as fuels for spark ignition engines. While ethanol is most commonly used, long chain alcohols such as butanol feature several advantages like increased heating value and reduced corrosive action. This study investigated the effect of fueling a port injection engine with iso-butanol, as compared to gasoline operation. Performance levels were maintained within the same limits as with the fossil fuel without modifications to any engine component. An additional electronic module was used for increasing fuel flow by extending the injection time. Fuel conversion efficiency decreased when the engine was fueled with iso-butanol by up to 9% at full load and by up to 11% at part load, calculated as relative values. Incomplete fuel evaporation was identified as the factor most likely to cause the drop in engine efficiency.

  19. Carbon materials as additives to WO3 for an enhanced conversion of simulated solar light

    Directory of Open Access Journals (Sweden)

    Rocío Jiménez Carmona

    2016-02-01

    Full Text Available We have explored the impact of the incorporation of nanoporous carbons as additives to tungsten oxide on the photocatalytic degradation of two recalcitrant pollutants: rhodamine B and phenol, under simulated solar light. For this purpose, WO3/carbon mixtures were prepared using three carbon materials with different properties (in terms of porosity, structural order and surface chemistry. Despite the low carbon content used (2 wt. %, a significant increase in the photocatalytic performance of the semiconductor was observed for all the catalysts. Moreover, the influence of the carbon additive on the performance of the photocatalysts was found to be very different for the two pollutants. Carbon additives of hydrophobic nature increased the photodegradation yield of phenol compared to bare WO3, likely due to the higher affinity and stronger interactions of phenol molecules towards basic nanoporous carbons. Oppositely, the use of acidic carbon additives led to higher rhodamine B conversions due to increased acidity of the WO3/carbon mixtures and the stronger affinity of the pollutant for acidic catalyst’s surfaces. As a result, the photooxidation of rhodamine B is favored by means of a coupled (photosensitized and photocatalytic degradation mechanism. All these results highlight the importance of favoring the interactions of the pollutant with the catalyst’s surface through a detailed design of the features of the photocatalyst.

  20. Large-scale cauliflower-shaped hierarchical copper nanostructures for efficient photothermal conversion

    Science.gov (United States)

    Fan, Peixun; Wu, Hui; Zhong, Minlin; Zhang, Hongjun; Bai, Benfeng; Jin, Guofan

    2016-07-01

    Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent heating up effect under the sunlight illumination. In the experiment of evaporating water, the structured surface yields an overall photothermal conversion efficiency over 60% under an illuminating solar power density of ~1 kW m-2. The presented technology provides a cost-effective, reliable, and simple way for realizing broadband omnidirectional light absorptive metal surfaces for efficient solar energy harvesting and utilization, which is highly demanded in various light harvesting, anti-reflection, and photothermal conversion applications. Since the structure is directly formed by femtosecond laser writing, it is quite suitable for mass production and can be easily extended to a large surface area.Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent

  1. Conversion to No-Till Improves Maize Nitrogen Use Efficiency in a Continuous Cover Cropping System

    Science.gov (United States)

    Habbib, Hazzar; Verzeaux, Julien; Nivelle, Elodie; Roger, David; Lacoux, Jérôme; Catterou, Manuella; Hirel, Bertrand; Dubois, Frédéric; Tétu, Thierry

    2016-01-01

    A two-year experiment was conducted in the field to measure the combined impact of tilling and N fertilization on various agronomic traits related to nitrogen (N) use efficiency and to grain yield in maize cultivated in the presence of a cover crop. Four years after conversion to no-till, a significant increase in N use efficiency N harvest index, N remobilization and N remobilization efficiency was observed both under no and high N fertilization conditions. Moreover, we observed that grain yield and grain N content were higher under no-till conditions only when N fertilizers were applied. Thus, agronomic practices based on continuous no-till appear to be a promising for increasing N use efficiency in maize. PMID:27711154

  2. Surface structural evolvement in the conversion of polyacrylonitrile precursors to carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Xin, E-mail: qx3023@nimte.ac.cn; Zou, Ruifen; OuYang, Qin; Wang, Xuefei; Zhang, Yonggang

    2015-02-01

    Highlights: • The characteristic striated topography of PAN precursors resulted from the wet spinning process could pass down to carbon fibers. • The ridges and grooves monitored became much more well-defined after the thermo-oxidation. • Both the depth and the width of longitudinal grooves decreased after the carbonization. • Carbon, nitrogen, oxygen and silicon were the governing elements on the fiber surface. - Abstract: Surface structural evolvement in the conversion of polyacrylonitrile (PAN) precursors to carbon fibers was investigated through scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). SEM results showed that the characteristic striated topography of PAN precursors resulted from the wet spinning process could pass down to carbon fibers. The fiber diameter gradually decreased from 11.3 μm to 5.5 μm and the corresponding density increased from 1.18 g/cm{sup 3} to 1.80 g/cm{sup 3} in the conversion of PAN precursors to carbon fibers. The ridges and grooves monitored by AFM became much more well-defined after the thermo-oxidation. However, the original longitudinal grooves were destroyed and both the depth and the width of longitudinal grooves decreased after the carbonization. XPS results revealed that carbon, nitrogen, oxygen and silicon were the governing elements on the fiber surface. The −C−C functional groups was the dominant groups and the relative contents of −C=O and −COO groups gradually increased in the process of thermo-oxidation and carbonization.

  3. Coating Carbon Nanosphere with Patchy Gold for Production of Highly Efficient Photothermal Agent.

    Science.gov (United States)

    Wang, Xiaoxiao; Cao, Dongwei; Tang, Xuejiao; Yang, Jingjing; Jiang, Daoyong; Liu, Mei; He, Nongyue; Wang, Zhifei

    2016-08-01

    Gold- or carbon-based photothermal therapy (PTT) agents have shown encouraging therapeutic effects of PTT in the near-infrared region (NIR) in many preclinical animal experiments. It is expected that gold/carbon hybrid nanomaterial will possess combinational NIR light absorption and can achieve further improvement in photothermal conversion efficiency. In this work, we design and construct a novel PTT agent by coating a carbon nanosphere with patchy gold. To synthesize this composite particle with Janus structure, a new versatile approach based on a facile adsorption-reduction method was presented. Different from the conventional fabrication procedures, the formation of patchy gold in this approach is mainly a thermodynamics-driven spontaneous process. The results show that when compared with the conventional PTT agent gold nanorod the obtained nanocomposites not only have higher photothermal conversion efficiency but also perform more thermally stable. On the basis of these outstanding photothermal effects, the in vitro and in vivo photothermal performances in a MCF-7 cells (human breast adenocarcinoma cell line) and mice were investigated separately. Additionally, to further illustrate the advantage of this asymmetric structure, their potential was explored by selective surface functionalization, taking advantage of the affinity of both patchy gold and carbon domain to different functional molecules. These results suggest that this new hybrid nanomaterial can be used as an effective PTT agent for cancer treatment in the future. PMID:27351062

  4. Metal-Free Counter Electrode for Efficient Dye-Sensitized Solar Cells through High Surface Area and Large Porous Carbon

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available Highly efficient, large mesoporous carbon is fabricated as a metal-free counter electrode for dye-sensitized solar cells. The mesoporous carbon shows very high energy conversion efficiency of 7.1% compared with activated carbon. The mesoporous carbon is prepared and characterized by nitrogen adsorption, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The nitrogen adsorption data reveals that the material possesses BET specific surface area ca.1300 m2/g and pore diameter 4.4 nm. Hexagonal rod-like morphology and ordered pore structure of mesoporous carbon are confirmed by electron microscopy data. The better performance of this carbon material is greatly benefited from its ordered interconnected mesoporous structure and high surface area.

  5. High-ratio voltage conversion in CMOS for efficient mains-connected standby

    CERN Document Server

    Meyvaert, Hans

    2016-01-01

    This book describes synergetic innovation opportunities offered by combining the field of power conversion with the field of integrated circuit (IC) design. The authors demonstrate how integrating circuits enables increased operation frequency, which can be exploited in power converters to reduce drastically the size of the discrete passive components. The authors introduce multiple power converter circuits, which are very compact as result of their high level of integration. First, the limits of high-power-density low-voltage monolithic switched-capacitor DC-DC conversion are investigated to enable on-chip power granularization. AC-DC conversion from the mains to a low voltage DC is discussed, enabling an efficient and compact, lower-power auxiliary power supply to take over the power delivery during the standby mode of mains-connected appliances, allowing the main power converter of these devices to be shut down fully. Discusses high-power-density monolithic switched-capacitor DC-DC conversion in bulk CMOS,...

  6. Power conversion efficiency exceeding the Shockley–Queisser limit in a ferroelectric insulator

    Science.gov (United States)

    Spanier, Jonathan E.; Fridkin, Vladimir M.; Rappe, Andrew M.; Akbashev, Andrew R.; Polemi, Alessia; Qi, Yubo; Gu, Zongquan; Young, Steve M.; Hawley, Christopher J.; Imbrenda, Dominic; Xiao, Geoffrey; Bennett-Jackson, Andrew L.; Johnson, Craig L.

    2016-09-01

    Ferroelectric absorbers, which promote carrier separation and exhibit above-gap photovoltages, are attractive candidates for constructing efficient solar cells. Using the ferroelectric insulator BaTiO3 we show how photogeneration and the collection of hot, non-equilibrium electrons through the bulk photovoltaic effect (BPVE) yields a greater-than-unity quantum efficiency. Despite absorbing less than a tenth of the solar spectrum, the power conversion efficiency of the BPVE device under 1 sun illumination exceeds the Shockley–Queisser limit for a material of this bandgap. We present data for devices that feature a single-tip electrode contact and an array with 24 tips (total planar area of 1 × 1 μm2) capable of generating a current density of 17 mA cm–2 under illumination of AM1.5 G. In summary, the BPVE at the nanoscale provides an exciting new route for obtaining high-efficiency photovoltaic solar energy conversion.

  7. Modeling recombination processes and predicting energy conversion efficiency of dye sensitized solar cells from first principles

    Science.gov (United States)

    Ma, Wei; Meng, Sheng

    2014-03-01

    We present a set of algorithms based on solo first principles calculations, to accurately calculate key properties of a DSC device including sunlight harvest, electron injection, electron-hole recombination, and open circuit voltages. Two series of D- π-A dyes are adopted as sample dyes. The short circuit current can be predicted by calculating the dyes' photo absorption, and the electron injection and recombination lifetime using real-time time-dependent density functional theory (TDDFT) simulations. Open circuit voltage can be reproduced by calculating energy difference between the quasi-Fermi level of electrons in the semiconductor and the electrolyte redox potential, considering the influence of electron recombination. Based on timescales obtained from real time TDDFT dynamics for excited states, the estimated power conversion efficiency of DSC fits nicely with the experiment, with deviation below 1-2%. Light harvesting efficiency, incident photon-to-electron conversion efficiency and the current-voltage characteristics can also be well reproduced. The predicted efficiency can serve as either an ideal limit for optimizing photovoltaic performance of a given dye, or a virtual device that closely mimicking the performance of a real device under different experimental settings.

  8. Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion.

    Science.gov (United States)

    Xing, Sida; Grassani, Davide; Kharitonov, Svyatoslav; Billat, Adrien; Brès, Camille-Sophie

    2016-05-01

    We experimentally demonstrate wavelength conversion in the 2 µm region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of -25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 µm. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 µm pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW. PMID:27137588

  9. Feasibility of sustaining the upland conversion program by establishing a domestic carbon market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To sustain the upland conversion program (UCP) in China after the government compensation expires, we suggest an establishment of a domestic carbon market where forest carbon from the UCP can be traded. Taking southwest China's Yunnan Province as an example, we explored the feasibility of switching the UCP to a carbon offset project. The breakeven carbon price which is equivalent to the opportunity cost of agricultural cultivation was estimated and then compared with the carbon price in the  international market. We found that it is feasible to change the UCP to a carbon offset project if the duration is longer than 10 years at a discount rate of 7%, and if the recent bid price (147.2 Yuan-t1) for Chinese carbon offset project prevails. The feasibility is better for converted land with lower productivity when the project duration is given. For a given site index, the feasibility is lower as pro-ject length is reduced. The results of sensitivity analysis show that the feasibility will be enhanced as the discount rate increases;however, the changes in the price of agricultural products and the amount of sequestered carbon have insignificant effects on the choice of sites and project duration.

  10. Photosynthesis: The Path of Carbon in Photosynthesis and the Primary Quantum Conversion Act of Photosynthesis

    Science.gov (United States)

    Calvin, Melvin

    1952-11-22

    This constitutes a review of the path of carbon in photosynthesis as it has been elaborated through the summer of 1952, with particular attention focused on those aspects of carbon metabolism and its variation which have led to some direct information regarding the primary quantum conversion act. An introduction to the arguments which have been adduced in support of the idea that chlorophyll is a physical sensitizer handing its excitation on to thioctic acid, a compound containing a strained 1, 2 -dithiolcyclopentane ring, is given.

  11. Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation

    Energy Technology Data Exchange (ETDEWEB)

    Schleyer, F.; Cairns, Iver H. [School of Physics, University of Sydney, NSW 2006 (Australia); Kim, E.-H. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2013-03-15

    Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence {theta} of the Langmuir/z-mode wave, temperature {beta}=T{sub e}/m{sub e}c{sup 2}, adiabatic index {gamma}, and orientation angle {phi} between the ambient density gradient {nabla}N{sub 0} and ambient magnetic field B{sub 0} in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of {theta}, {gamma}, and {beta} with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency {epsilon} is strongly dependent on {gamma}{beta}, {phi} and {theta}, with {epsilon}{proportional_to}({gamma}{beta}){sup 1/2} and {theta}{proportional_to}({gamma}{beta}){sup 1/2}. The power conversion efficiency {epsilon}{sub p}, on the other hand, is independent of {gamma}{beta} but does vary significantly with {theta} and {phi}. The efficiencies are shown to be maximum for approximately perpendicular density gradients ({phi} Almost-Equal-To 90 Degree-Sign ) and minimal for parallel orientation ({phi}=0 Degree-Sign ) and both the energy and power conversion efficiencies peak at the same {theta}.

  12. Enhanced conversion efficiency in perovskite solar cells by effectively utilizing near infrared light

    Science.gov (United States)

    Que, Meidan; Que, Wenxiu; Yin, Xingtian; Chen, Peng; Yang, Yawei; Hu, Jiaxing; Yu, Boyan; Du, Yaping

    2016-07-01

    Up-conversion β-NaYF4:Yb3+,Tm3+/NaYF4 core-shell nanoparticles (NYF NPs) with a high luminous intensity in the visible light region were synthesized by a hydrothermal reaction process. Photocurrent densities of the mesoscopic perovskite solar cells fabricated by incorporating up-conversion NYF NPs into the electron transporting layer are effectively enhanced. The effects of the thicknesses of the electron transporting layer and the weight ratio of up-conversion NYF NPs/TiO2 on the power conversion efficiency (PCE) of the as-fabricated devices were also investigated. The results indicate that the PCE of the optimized device achieves 16.9%, which is 20% higher than that of the device without introducing NYF NPs, and the steady-state PCE of the as-fabricated devices is close to its transient-state PCE. The up-conversion effect of NYF NPs is conducive to higher device performance rather than the nanoparticles as scattering centers to increase possible light absorption of the perovskite film or the electronic effect of the NaYF4 shell surface. These results can be further confirmed by finite-difference time-domain simulation. Photoluminescence results suggest that the multiphonon-assistance can accelerate the nonradiative recombination process at a lower temperature. Incorporating NYF NPs into the electron transporting layer opens a new approach to a promising family of electron transporting materials for mesoscopic perovskite solar cells.Up-conversion β-NaYF4:Yb3+,Tm3+/NaYF4 core-shell nanoparticles (NYF NPs) with a high luminous intensity in the visible light region were synthesized by a hydrothermal reaction process. Photocurrent densities of the mesoscopic perovskite solar cells fabricated by incorporating up-conversion NYF NPs into the electron transporting layer are effectively enhanced. The effects of the thicknesses of the electron transporting layer and the weight ratio of up-conversion NYF NPs/TiO2 on the power conversion efficiency (PCE) of the as

  13. Theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions.

    Science.gov (United States)

    Cushing, Scott K; Bristow, Alan D; Wu, Nianqiang

    2015-11-28

    Plasmonics can enhance solar energy conversion in semiconductors by light trapping, hot electron transfer, and plasmon-induced resonance energy transfer (PIRET). The multifaceted response of the plasmon and multiple interaction pathways with the semiconductor makes optimization challenging, hindering design of efficient plasmonic architectures. Therefore, in this paper we use a density matrix model to capture the interplay between scattering, hot electrons, and dipole-dipole coupling through the plasmon's dephasing, including both the coherent and incoherent dynamics necessary for interactions on the plasmon's timescale. The model is extended to Shockley-Queisser limit calculations for both photovoltaics and solar-to-chemical conversion, revealing the optimal application of each enhancement mechanism based on plasmon energy, semiconductor energy, and plasmon dephasing. The results guide application of plasmonic solar-energy harvesting, showing which enhancement mechanism is most appropriate for a given semiconductor's weakness, and what nanostructures can achieve the maximum enhancement.

  14. Electrokinetic Energy Conversion in Nanofluidic Channels: Addressing the Loose Ends in Nanodevice Efficiency

    CERN Document Server

    Bakli, Chirodeep

    2014-01-01

    We bring out a non-trivial coupling of the intrinsic wettability, surface charge and electrokinetic energy conversion characteristics of nanofluidic devices. Our analyses demonstrate that nanofluidic energy conversion efficiencies may get amplified with increase in surface charge density, not perpetually, but only over a narrow regime of low surface charges, and may get significantly arrested to reach a plateau beyond a threshold surface charging condition, as attributed to a complex interplay between fluid structuration and ionic transport within a charged interfacial layer. We explain the corresponding findings from our molecular dynamics simulations with the aid of a simple modified continuum based theory. We attribute our findings to hitherto-unexplored four-way integration of surface charge, interfacial slip, ionic transport, and the water molecule structuration. The consequent complex non-linear nature of the energy transfer characteristics may bear far-ranging scientific and technological implications ...

  15. Highly integrated CO2 capture and conversion: Direct synthesis of cyclic carbonates from industrial flue gas

    KAUST Repository

    Barthel, Alexander

    2016-02-08

    Robust and selective catalytic systems based on early transition metal halides (Y, Sc, Zr) and organic nucleophiles were found able to quantitatively capture CO2 from diluted streams via formation of hemicarbonate species and to convert it to cyclic organic carbonates under ambient conditions. This observation was exploited in the direct and selective chemical fixation of flue gas CO2 collected from an industrial exhaust, affording high degrees of CO2 capture and conversion.

  16. Electromagnetic Spectrum Analysis and Its Influence on the Photoelectric Conversion Efficiency of Solar Cells.

    Science.gov (United States)

    Hu, Kexiang; Ding, Enjie; Wangyang, Peihua; Wang, Qingkang

    2016-06-01

    The electromagnetic spectrum and the photoelectric conversion efficiency of the silicon hexagonal nanoconical hole (SiHNH) arrays based solar cells is systematically analyzed according to Rigorous Coupled Wave Analysis (RCWA) and Modal Transmission Line (MTL) theory. An ultimate efficiency of the optimized SiHNH arrays based solar cell is up to 31.92% in consideration of the absorption spectrum, 4.52% higher than that of silicon hexagonal nanoconical frustum (SiHNF) arrays. The absorption enhancement of the SiHNH arrays is due to its lower reflectance and more supported guided-mode resonances, and the enhanced ultimate efficiency is insensitive to bottom diameter (D(bot)) of nanoconical hole and the incident angle. The result provides an additional guideline for the nanostructure surface texturing fabrication design for photovoltaic applications. PMID:27427668

  17. Enhancing Heralding Efficiency and Biphoton Rate in Type-I Spontaneous Parametric Down-Conversion

    CERN Document Server

    Guilbert, Hannah E

    2014-01-01

    The nonlinear optical process of spontaneous parametric down-conversion (SPDC) is widely studied for applications in quantum information science due to its ability to produce two photons that can be entangled in many degrees of freedom. For applications in quantum communication, two metrics of this process are particularly important: heralding efficiency and total joint rate. Here, we derive expressions for both quantities for a variety of different beam geometries and frequencies. We pay specific attention to the spectrum of both biphotons and individual photons. We reveal the underlying mechanisms responsible for the spectral shape and show they differ for different geometries and frequencies. We then use these spectra to calculate heralding efficiency and joint count rate and examine how each of these metrics changes with different geometries, frequencies, and spectral filtering and beam parameters. Interestingly, we find very high heralding efficiencies are achievable for collinear geometries, while nonco...

  18. Efficient photosynthesis of carbon monoxide from CO2 using perovskite photovoltaics.

    Science.gov (United States)

    Schreier, Marcel; Curvat, Laura; Giordano, Fabrizio; Steier, Ludmilla; Abate, Antonio; Zakeeruddin, Shaik M; Luo, Jingshan; Mayer, Matthew T; Grätzel, Michael

    2015-01-01

    Artificial photosynthesis, mimicking nature in its efforts to store solar energy, has received considerable attention from the research community. Most of these attempts target the production of H2 as a fuel and our group recently demonstrated solar-to-hydrogen conversion at 12.3% efficiency. Here, in an effort to take this approach closer to real photosynthesis, which is based on the conversion of CO2, we demonstrate the efficient reduction of CO2 to carbon monoxide driven solely by simulated sunlight using water as the electron source. Employing series-connected perovskite photovoltaics and high-performance catalyst electrodes, we reach a solar-to-CO efficiency exceeding 6.5%, which represents a new benchmark in sunlight-driven CO2 conversion. Considering hydrogen as a secondary product, an efficiency exceeding 7% is observed. Furthermore, this study represents one of the first demonstrations of extended, stable operation of perovskite photovoltaics, whose large open-circuit voltage is shown to be particularly suited for this process.

  19. Modelling carbon dynamics from urban land conversion: fundamental model of city in relation to a local carbon cycle

    Directory of Open Access Journals (Sweden)

    Schellnhuber Hans-Joachim

    2006-08-01

    Full Text Available Abstract Background The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process of urbanization to the Global Carbon Cycle (GCC. Note that, on the contrary to many investigations that have considered direct anthropogenic emission of CO2(urbanized territories produce ca. 96–98% of it, we are interested in more subtle, and up until the present time, weaker processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized". Results In order to fulfil this task, we first develop a fundamental model of urban space, since the type of land cover within a city makes a difference for a local carbon cycle. Hence, a city is sub-divided by built-up, „green" (parks, etc. and informal settlements (favelas fractions. Another aspect is a sub-division of the additional two regions, which makes the total number reaching eight regions, while the UN divides the world by six. Next, the basic model of the local carbon cycle for urbanized territories is built. We consider two processes: carbon emissions as a result of conversion of natural lands caused by urbanization; and the transformation of carbon flows by "urbanized" ecosystems; when carbon, accumulated by urban vegetation, is exported to the neighbouring territories. The total carbon flow in the model depends, in general, on two groups of parameters. The first includes the NPP, and the sum of living biomass and dead organic matter of ecosystems involved in the process of urbanization, and namely them we calculate here, using a new more realistic approach and taking into account the difference in regional cities' evolution. Conclusion There is also another group of parameters, dealing with the areas of urban territories, and their annual increments. A method of dynamic forecasting

  20. Basic aspects for improving the energy conversion efficiency of hetero-junction organic photovoltaic cells.

    Science.gov (United States)

    Ryuzaki, Sou; Onoe, Jun

    2013-01-01

    Hetero-junction organic photovoltaic (OPV) cells consisting of donor (D) and acceptor (A) layers have been regarded as next-generation PV cells, because of their fascinating advantages, such as lightweight, low fabrication cost, resource free, and flexibility, when compared to those of conventional PV cells based on silicon and semiconductor compounds. However, the power conversion efficiency (η) of the OPV cells has been still around 8%, though more than 10% efficiency has been required for their practical use. To fully optimize these OPV cells, it is necessary that the low mobility of carriers/excitons in the OPV cells and the open circuit voltage (V OC), of which origin has not been understood well, should be improved. In this review, we address an improvement of the mobility of carriers/excitons by controlling the crystal structure of a donor layer and address how to increase the V OC for zinc octaethylporphyrin [Zn(OEP)]/C60 hetero-junction OPV cells [ITO/Zn(OEP)/C60/Al]. It was found that crystallization of Zn(OEP) films increases the number of inter-molecular charge transfer (IMCT) excitons and enlarges the mobility of carriers and IMCT excitons, thus significantly improving the external quantum efficiency (EQE) under illumination of the photoabsorption band due to the IMCT excitons. Conversely, charge accumulation of photo-generated carriers in the vicinity of the donor/acceptor (D/A) interface was found to play a key role in determining the V OC for the OPV cells.

  1. Basic aspects for improving the energy conversion efficiency of hetero-junction organic photovoltaic cells

    Directory of Open Access Journals (Sweden)

    Sou Ryuzaki

    2013-07-01

    Full Text Available Hetero-junction organic photovoltaic (OPV cells consisting of donor (D and acceptor (A layers have been regarded as next-generation PV cells, because of their fascinating advantages, such as lightweight, low fabrication cost, resource free, and flexibility, when compared to those of conventional PV cells based on silicon and semiconductor compounds. However, the power conversion efficiency (η of the OPV cells has been still around 8%, though more than 10% efficiency has been required for their practical use. To fully optimize these OPV cells, it is necessary that the low mobility of carriers/excitons in the OPV cells and the open circuit voltage (VOC, of which origin has not been understood well, should be improved. In this review, we address an improvement of the mobility of carriers/excitons by controlling the crystal structure of a donor layer and address how to increase the VOC for zinc octaethylporphyrin [Zn(OEP]/C60 hetero-junction OPV cells [ITO/Zn(OEP/C60/Al]. It was found that crystallization of Zn(OEP films increases the number of inter-molecular charge transfer (IMCT excitons and enlarges the mobility of carriers and IMCT excitons, thus significantly improving the external quantum efficiency (EQE under illumination of the photoabsorption band due to the IMCT excitons. Conversely, charge accumulation of photo-generated carriers in the vicinity of the donor/acceptor (D/A interface was found to play a key role in determining the VOC for the OPV cells.

  2. Estimating Energy Conversion Efficiency of Thermoelectric Materials: Constant Property Versus Average Property Models

    Science.gov (United States)

    Armstrong, Hannah; Boese, Matthew; Carmichael, Cody; Dimich, Hannah; Seay, Dylan; Sheppard, Nathan; Beekman, Matt

    2016-08-01

    Maximum thermoelectric energy conversion efficiencies are calculated using the conventional "constant property" model and the recently proposed "cumulative/average property" model (Kim et al. in Proc Natl Acad Sci USA 112:8205, 2015) for 18 high-performance thermoelectric materials. We find that the constant property model generally predicts higher energy conversion efficiency for nearly all materials and temperature differences studied. Although significant deviations are observed in some cases, on average the constant property model predicts an efficiency that is a factor of 1.16 larger than that predicted by the average property model, with even lower deviations for temperature differences typical of energy harvesting applications. Based on our analysis, we conclude that the conventional dimensionless figure of merit ZT obtained from the constant property model, while not applicable for some materials with strongly temperature-dependent thermoelectric properties, remains a simple yet useful metric for initial evaluation and/or comparison of thermoelectric materials, provided the ZT at the average temperature of projected operation, not the peak ZT, is used.

  3. Efficiency enhancement of the ocean thermal energy conversion system with a vapor–vapor ejector

    Directory of Open Access Journals (Sweden)

    Ho-Saeng Lee

    2015-03-01

    Full Text Available In this article, 20 kW ocean thermal energy conversion with a vapor–vapor ejector is newly proposed. As a vapor–vapor ejector is installed in the system, the pressure difference between the turbine inlet and outlet increases. Therefore, the amount of the working fluid required for the total turbine work of 20 kW is less than when no vapor–vapor ejector is installed. Therefore, installing a vapor–vapor ejector in the system decreases the evaporation capacity and the pump work. The performance analysis considered the outlet pressure of the high-stage turbine, the mass flow ratio of the working fluid at the outlet of a separator just after the high-stage turbine, and the nozzle diameters of the vapor–vapor ejector. As the outlet pressure of high-stage turbine becomes lower, the turbine gross power of high-stage turbine and system efficiency increase although lower outlet pressure of high-stage turbine results in lower ejector performance. Similarly, in terms of mass flow ratio, the highest system efficiency was shown at mass flow ratio of 0.4 at the outlet of a separator just after the high-stage turbine. On the other hand, the performance of the ejector at mass flow ratio of 0.5 at the outlet of a separator was largest. When the nozzle diameters of the vapor–vapor ejector are properly designed, the vapor–vapor ejector shows the highest performance. After the optimization of the operation parameters, system efficiency of the proposed ocean thermal energy conversion power cycle was 2.47%, relatively 15% higher than that of the basic ocean thermal energy conversion power cycle (2.2%.

  4. Method of Measuring the Efficiency of the Conversion of Nuclear Energy into Optical Energy

    Directory of Open Access Journals (Sweden)

    Erlan G. Batyrbekov

    2015-01-01

    Full Text Available A method of measuring the efficiency of converting nuclear energy into optical energy was developed based on correlations between intensities of the research line and the nitrogen second positive system in an Ar-N2 mixture. In addition, the values of the coefficient of the conversion of nuclear energy into radiation at the lines of a Hg triplet in mixtures of Хе-Hg and Kr-Hg were determined. The values measured correspond to a selectiveness of pumping of 73S1 that was close to 1 (δ=0.8±0.2.

  5. High efficiency chemical energy conversion system based on a methane catalytic decomposition reaction and two fuel cells: Part I. Process modeling and validation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghua; Tian, Ye; Li, Hongjiao; Jia, Lijun; Xia, Chun; Li, Yongdan [Tianjin Key Laboratory of Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Thompson, Levi T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2010-10-01

    A highly efficient integrated energy conversion system is built based on a methane catalytic decomposition reactor (MCDR) together with a direct carbon fuel cell (DCFC) and an internal reforming solid oxide fuel cell (IRSOFC). In the MCDR, methane is decomposed to pure carbon and hydrogen. Carbon is used as the fuel of DCFC to generate power and produce pure carbon dioxide. The hydrogen and unconverted methane are used as the fuel in the IRSOFC. A gas turbine cycle is also used to produce more power output from the thermal energy generated in the IRSOFC. The output performance and efficiency of both the DCFC and IRSOFC are investigated and compared by development of exact models of them. It is found that this system has a unique loading flexibility due to the good high-loading property of DCFC and the good low loading property of IRSOFC. The effects of temperature, pressure, current densities, and methane conversion on the performance of the fuel cells and the system are discussed. The CO{sub 2} emission reduction is effective, up to 80%, can be reduced with the proposed system. (author)

  6. Conversion of methane-derived carbon and microbial community in enrichment cultures in response to O2 availability.

    Science.gov (United States)

    Wei, Xiao-Meng; He, Ruo; Chen, Min; Su, Yao; Ma, Ruo-Chan

    2016-04-01

    Methanotrophs not only play an important role in mitigating CH4 emissions from the environment, but also provide a large quantity of CH4-derived carbon to their habitats. In this study, the distribution of CH4-derived carbon and microbial community was investigated in a consortium enriched at three O2 tensions, i.e., the initial O2 concentrations of 2.5 % (LO-2), 5 % (LO-1), and 21 % (v/v) (HO). The results showed that compared with the O2-limiting environments (2.5 and 5 %), more CH4-derived carbon was converted into CO2 and biomass under the O2 sufficient condition (21 %). Besides biomass and CO2, a high conversion efficiency of CH4-derived carbon to dissolved organic carbon was detected in the cultures, especially in LO-2. Quantitative PCR and Miseq sequencing both showed that the abundance of methanotroph increased with the increasing O2 concentrations. Type II methanotroph Methylocystis dominated in the enrichment cultures, accounting for 54.8, 48.1, and 36.9 % of the total bacterial 16S rRNA gene sequencing reads in HO, LO-1, and LO-2, respectively. Methylotrophs, mainly including Methylophilus, Methylovorus, Hyphomicrobium, and Methylobacillus, were also abundant in the cultures. Compared with the O2 sufficient condition (21 %), higher microbial biodiversity (i.e., higher Simpson and lower Shannon indexes) was detected in LO-2 enriched at the initial O2 concentration of 2.5 %. These findings indicated that compared with the O2 sufficient condition, more CH4-derived carbon was exuded into the environments and promoted the growth of non-methanotrophic microbes in O2-limiting environments. PMID:26728286

  7. Managing carbon emissions in China through building energy efficiency.

    Science.gov (United States)

    Li, Jun; Colombier, Michel

    2009-06-01

    This paper attempts to analyse the role of building energy efficiency (BEE) in China in addressing climate change mitigation. It provides an analysis of the current situation and future prospects for the adoption of BEE technologies in Chinese cities. It outlines the economic and institutional barriers to large-scale deployment of the sustainable, low-carbon, and even carbon-free construction techniques. Based on a comprehensive overview of energy demand characteristics and development trends driven by economic and demographic growth, different policy tools for cost-effective CO(2) emission reduction in the Chinese construction sector are described. We propose a comprehensive approach combining building design and construction, and the urban planning and building material industries, in order to drastically improve BEE during this period of rapid urban development. A coherent institutional framework needs to be established to ensure the implementation of efficiency policies. Regulatory and incentive options should be integrated into the policy portfolios of BEE to minimise the efficiency gap and to realise sizeable carbon emissions cuts in the next decades. We analyse in detail several policies and instruments, and formulate relevant policy proposals fostering low-carbon construction technology in China. Specifically, Our analysis shows that improving building energy efficiency can generate considerable carbon emissions reduction credits with competitive price under the CDM framework. PMID:19344996

  8. Managing carbon emissions in China through building energy efficiency.

    Science.gov (United States)

    Li, Jun; Colombier, Michel

    2009-06-01

    This paper attempts to analyse the role of building energy efficiency (BEE) in China in addressing climate change mitigation. It provides an analysis of the current situation and future prospects for the adoption of BEE technologies in Chinese cities. It outlines the economic and institutional barriers to large-scale deployment of the sustainable, low-carbon, and even carbon-free construction techniques. Based on a comprehensive overview of energy demand characteristics and development trends driven by economic and demographic growth, different policy tools for cost-effective CO(2) emission reduction in the Chinese construction sector are described. We propose a comprehensive approach combining building design and construction, and the urban planning and building material industries, in order to drastically improve BEE during this period of rapid urban development. A coherent institutional framework needs to be established to ensure the implementation of efficiency policies. Regulatory and incentive options should be integrated into the policy portfolios of BEE to minimise the efficiency gap and to realise sizeable carbon emissions cuts in the next decades. We analyse in detail several policies and instruments, and formulate relevant policy proposals fostering low-carbon construction technology in China. Specifically, Our analysis shows that improving building energy efficiency can generate considerable carbon emissions reduction credits with competitive price under the CDM framework.

  9. Suppression of Tla1 gene expression for improved solar conversion efficiency and photosynthetic productivity in plants and algae

    Science.gov (United States)

    Melis, Anastasios; Mitra, Mautusi

    2010-06-29

    The invention provides method and compositions to minimize the chlorophyll antenna size of photosynthesis by decreasing TLA1 gene expression, thereby improving solar conversion efficiencies and photosynthetic productivity in plants, e.g., green microalgae, under bright sunlight conditions.

  10. Carbon dioxide efficiency of terrestrial enhanced weathering.

    Science.gov (United States)

    Moosdorf, Nils; Renforth, Phil; Hartmann, Jens

    2014-05-01

    Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimistic scenarios. The results show that the choice of source rocks and material comminution technique dominate the CO2 efficiency of enhanced weathering. CO2 emissions from transport amount to on average 0.5-3% of potentially sequestered CO2. The emissions of material mining and application are negligible. After accounting for all emissions, 0.5-1.0 t CO2 can be sequestered on average per tonne of rock, translating into a unit cost from 1.6 to 9.9 GJ per tonne CO2 sequestered by enhanced weathering. However, to control or reduce atmospheric CO2 concentrations substantially with enhanced weathering would require very large amounts of rock. Before enhanced weathering could be applied on large scales, more research is needed to assess weathering rates, potential side effects, social acceptability, and mechanisms of governance.

  11. The affect of erbium hydride on the conversion efficience to accelerated protons from ultra-shsort pulse laser irradiated foils

    Energy Technology Data Exchange (ETDEWEB)

    Offermann, Dustin Theodore [The Ohio State Univ., Columbus, OH (United States)

    2008-01-01

    This thesis work explores, experimentally, the potential gains in the conversion efficiency from ultra-intense laser light to proton beams using erbium hydride coatings. For years, it has been known that contaminants at the rear surface of an ultra-intense laser irradiated thin foil will be accelerated to multi-MeV. Inertial Confinement Fusion fast ignition using proton beams as the igniter source requires of about 1016 protons with an average energy of about 3MeV. This is far more than the 1012 protons available in the contaminant layer. Target designs must include some form of a hydrogen rich coating that can be made thick enough to support the beam requirements of fast ignition. Work with computer simulations of thin foils suggest the atomic mass of the non-hydrogen atoms in the surface layer has a strong affect on the conversion efficiency to protons. For example, the 167amu erbium atoms will take less energy away from the proton beam than a coating using carbon with a mass of 12amu. A pure hydrogen coating would be ideal, but technologically is not feasible at this time. In the experiments performed for my thesis, ErH3 coatings on 5 μm gold foils are compared with typical contaminants which are approximately equivalent to CH1.7. It will be shown that there was a factor of 1.25 ± 0.19 improvement in the conversion efficiency for protons above 3MeV using erbium hydride using the Callisto laser. Callisto is a 10J per pulse, 800nm wavelength laser with a pulse duration of 200fs and can be focused to a peak intensity of about 5 x 1019W/cm2. The total number of protons from either target type was on the order of 1010. Furthermore, the same experiment was performed on the Titan laser, which has a 500fs pulse duration, 150J of energy and can be focused to about 3 x 1020 W/cm2. In this experiment 1012 protons were seen from both erbium hydride and

  12. Development of a high-energy distributed energy source electromagnetic railgun with improved energy conversion efficiency

    International Nuclear Information System (INIS)

    Vought Corporation in cooperation with the Center for Electromechanics at the University of Texas (CEM-UT) has developed under sponsorship by the Defense Advanced Research Projects Agency (DARPA) and the Army Armament, Munitions, and Chemical Command (AMCCOM) a high-energy distributed energy source (DES) electromagnetic (EM) railgun accelerator. This paper discusses the development and current status of the DES railgun which has the design capability to launch projectile masses up to 60 grams to the 3-4 km/sec velocity regime with energy conversion efficiencies above 35 percent. These goals are being accomplished through utilization of scaled-energy CEM-UT railgun experiments for sequenced timing/staging and a full energy (575 kJ) design at Vought for high efficiency capability. The operational Vought single-pulse railgun forms the baseline for the full energy testing

  13. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    International Nuclear Information System (INIS)

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle versus wavelength to second order, we efficiently doubled tunable fundamental light near 660nm over a range of 80nm, using a 4-mm-long type I β-barium borate crystal without tuning the crystal angle. Another set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 μrad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%. copyright 1998 Optical Society of America

  14. Comparative Evaluation of Feed Conversion Efficiency and Mortality Rate of Two Broiler Strains under the Same Dietary Conditions

    Directory of Open Access Journals (Sweden)

    A.G. Badamasi

    2014-02-01

    Full Text Available This study is aimed at comparing the feed conversion efficiency and mortality rate of Hubbard and Arboracre commercial broiler chicks treated under the same dietary and environmental condition. A total of 200 broiler chicks comprising of one 100 Hubbard and one hundred Arboracre strains were used in the comparative evaluation of their feed conversion efficiency and mortality rate from day old to 56 days (8 weeks of age. Body weight was taken three times in a week. Feed intakes as well as the mortality rate were taken daily. Data obtained from body weight and feed intake were computed statistically to obtain the feed conversion efficiency. Hubbard broiler strain shows the feed conversion efficiency of 111.6247±2.8487, 82.35±1.0879, 58.72±0.75536 and 45.4407±0.80352 at 2, 4, 6 and 8 weeks of age while Aboracre strain attained the feed conversion efficiency of 114.615±4.1562, 89.105±2.79432, 75.8299±0.75536 and 54.3710±0.80352 at 2, 4, 6 and 8 weeks of age. Hubbard broiler strain has the mortality rate of 17.5% while arboracre strain has the mortality rate of 26.5% at 8 weeks of age. Under the same management system, arboracre strain showed superiority in feed conversion efficiency and mortality rate over Hubbard strain.

  15. Conversion from cropland to short rotation coppice willow and poplar: Accumulation of soil organic carbon

    Science.gov (United States)

    Georgiadis, Petros; Stupak, Inge; Vesterdal, Lars; Raulund-Rasmussen, Karsten

    2015-04-01

    Increased demand for bioenergy has intensified the production of Short Rotation Coppice (SRC) willow and poplar in temperate zones. We used a combined chronosequence and paired plot approach to study the potential of SRC willow and poplar stands to increase the soil carbon stock compared to stocks of the previous arable land-use. The study focused on well-drained soils. We sampled soil from 30 SRC stands in Denmark and southern Sweden including soils from their adjacent arable fields. The 18 willow and 12 poplar stands formed a chronosequence ranging between 4 and 29 years after conversion. The soil was sampled both with soil cores taken by fixed depths of 0-5, 5-10, 10-15, 15-25, and 25-40 cm and by genetic horizons from soil pits to 1m depth. The aim of the study was to estimate the difference and the ratio between soil carbon contents of the SRC and annual crop land and analyze the results as a chronosequence to examine the effect of age after conversion on the difference. Covariates such as soil type, fertilization type and harvest frequency were also taken into account. Preliminary results suggest an overall increase in carbon stocks over time with average accumulation rates ranging from 0.25 to 0.4 Mg ha-1 yr-1 in willow and poplar stands. Poplar stands had higher rates of C gain, probably due to less frequent harvesting. The differences in carbon between the SRC and the paired cropland were initially negative but changed to positive over time, implying loss of carbon after conversion and a later gain in soil carbon with stand age. Pairwise differences ranged from -25 Mg C ha-1 to 37 Mg C ha-1 for the top 40 cm. The carbon stock ratio of the SRC stand to the arable land was estimated to minimize the effect of site-related factors. The results of this analysis suggested that the ratio increased significantly with age after conversion for the top 10 cm of the soil, both for poplar and willow. A slight increase with age was also noticed at the deeper depths, but

  16. Improved Power Conversion Efficiency of InP Solar Cells Using Organic Window Layers

    Energy Technology Data Exchange (ETDEWEB)

    Li, N; Lee, K.; Renshaw, C. K.; Xiao, X.; Forrest, Stephen R.

    2011-01-01

    We employ the organic semiconductor 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) as a nanometer thick window layer for p-InP/indium tin oxide (ITO) Schottky barrierdiodesolar cells. The power conversion efficiency is enhanced compared to ITO/InP cells lacking the PTCDA window layer, primarily due to neutralizing InP surface state charges via hole injection from the PTCDA. This leads to an increased ITO/p-InP Schottky barrier height, and hence to an increased open circuit voltage. The power conversion efficiency of the cells increases from 13.2±0.5% for the ITO/InP cell to 15.4±0.4% for the ITO/4 nm PTCDA/p-InP cell under 1 sun, AM1.5G simulated solar illumination. The PTCDA window layer is also shown to contribute to the photocurrent by light absorption followed by exciton dissociation at the organic/inorganic semiconductor interface.

  17. Inorganic hole conductor-based lead halide perovskite solar cells with 12.4% conversion efficiency

    KAUST Repository

    Qin, Peng

    2014-05-12

    Organo-lead halide perovskites have attracted much attention for solar cell applications due to their unique optical and electrical properties. With either low-temperature solution processing or vacuum evaporation, the overall conversion efficiencies of perovskite solar cells with organic hole-transporting material were quickly improved to over 15% during the last 2 years. However, the organic hole-transporting materials used are normally quite expensive due to complicated synthetic procedure or high-purity requirement. Here, we demonstrate the application of an effective and cheap inorganic p-type hole-transporting material, copper thiocyanate, on lead halide perovskite-based devices. With low-temperature solution-process deposition method, a power conversion efficiency of 12.4% was achieved under full sun illumination. This work represents a well-defined cell configuration with optimized perovskite morphology by two times of lead iodide deposition, and opens the door for integration of a class of abundant and inexpensive material for photovoltaic application. © 2014 Macmillan Publishers Limited.

  18. Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes

    Science.gov (United States)

    Dong, Guo-Xiang; Shi, Hong-Yu; Xia, Song; Li, Wei; Zhang, An-Xue; Xu, Zhuo; Wei, Xiao-Yong

    2016-08-01

    In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency, covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%. At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471292, 61331005, 61471388, 51277012, 41404095, and 61501365), the 111 Project, China (Grant No. B14040), the National Basic Research Program of China (Grant No. 2015CB654602), and the China Postdoctoral Science Foundation ( Grant No. 2015M580849).

  19. Direct nitrogen fixation at the edges of graphene nanoplatelets as efficient electrocatalysts for energy conversion.

    Science.gov (United States)

    Jeon, In-Yup; Choi, Hyun-Jung; Ju, Myung Jong; Choi, In Taek; Lim, Kimin; Ko, Jaejung; Kim, Hwan Kyu; Kim, Jae Cheon; Lee, Jae-Joon; Shin, Dongbin; Jung, Sun-Min; Seo, Jeong-Min; Kim, Min-Jung; Park, Noejung; Dai, Liming; Baek, Jong-Beom

    2013-01-01

    Nitrogen fixation is essential for the synthesis of many important chemicals (e.g., fertilizers, explosives) and basic building blocks for all forms of life (e.g., nucleotides for DNA and RNA, amino acids for proteins). However, direct nitrogen fixation is challenging as nitrogen (N₂) does not easily react with other chemicals. By dry ball-milling graphite with N₂, we have discovered a simple, but versatile, scalable and eco-friendly, approach to direct fixation of N₂ at the edges of graphene nanoplatelets (GnPs). The mechanochemical cracking of graphitic C--C bonds generated active carbon species that react directly with N₂ to form five- and six-membered aromatic rings at the broken edges, leading to solution-processable edge-nitrogenated graphene nanoplatelets (NGnPs) with superb catalytic performance in both dye-sensitized solar cells and fuel cells to replace conventional Pt-based catalysts for energy conversion.

  20. Investigation on the influence of BBO thermal-induced phase mismatching in 266nm UV laser conversion efficiency

    Science.gov (United States)

    Yu, Kai; Jin, Guangyong; Yu, Miao; Huang, Zhulong; Zhai, Ruizhi; Wang, Lei

    2014-12-01

    266nm UV laser has a wide range of applications in many fields, such as laser medical treatment, laser processing, precision measure and other applications for the reason of its advantages in wavelength, small diffraction effects, high single-photon energy, and high resolution and so on. BBO crystals absorb parts of the fundamental laser energy and second harmonic laser energy are unavoidable, and thus the temperature raise, so that the existing crystal phase matching conditions change, resulting in phase mismatching in the high-power frequency doubling, greatly influence the 266nm UV laser conversion efficiency. To further study the effect of phase mismatching to conversion efficiency, and improve the conversion efficiency, output power and other output characteristics of 266nm laser, the article mainly describe from the following three aspects. Firstly, took the use of three-dimensional nonlinear crystal temperature distribution which is obtained, the process of BBO crystal thermal-induced phase mismatching is analyzed. Secondly, based on frequency doubling theory, the effects of the thermal-induced phase mismatching affected of conversion in crystals are analyzed. Combining with the phase mismatching of the three-dimensional distributions, the fourth harmonic conversion efficiency with thermal phase mismatching changes of BBO 266nm UV laser are simulated for the first time. Thirdly, by using MATLAB software, the effects of phase mismatching to conversion efficiency in crystal for different waist radius, 532nm laser power and the fundamental beam quality are simulated. The results indicate a good physical interpretation of reasons of high power laser frequency doubling system. It shows that the model established explains the reason of the reduction of conversion efficiency, output power and the beam quality excellently. All results make a leading sense to the research on the compensating of the phase mismatching and on the improvement of conversion efficiency.

  1. Audio power amplifier techniques with energy efficient power conversion. Vol. 1

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Karsten

    1998-04-01

    A fundamental study of both analog and digital pulse modulation methods is carried out. A novel class of multi-level pulse modulation methods - Phase Shifted Carrier Pulse Width Modulation (PSCPWM) - is introduced and show to have several advantageous features, primarily caused by the much improved synthesis of the modulating signal. Enhanced digital pulse modulation methods for digital Pulse Modulation Amplifier (PMA) systems are investigated, and a simple methodology for digital PWM modulator synthesis is devised. It is concluded, that the modulator performance is not a limitation in the system, regardless of the domain of modulator implementation. Power conversion in PMA systems is adressed from the perspective of both linearity and efficienty optimization. Based on detailed studies of the distortion mechanisms in the power conversion stage it is concluded, that this is the fundamental limitation on system performance due to several physical limitations. The analysis of general power stage efficiency concludes that dramatic improvements in energy efficiency are possible with PMA systems that are optimized for efficiency. A control system design methodology is devised as a platform for synthesis of robust control systems. Investigations of three fundamental control structures show that even simple control systems offer a remarkable value, although the considered topologies also have their limitations which is verified by practical evaluation in hardware. A novel control method is introduced - Multivariable Enhanced Cascade Control (MECC). MECC provides flexible control over all essential system parameters and is furthermore simple in realization. Practical evaluation of a MECC based PMA shows state-of-the-art performance. The application of non-linear control methods is investigated with the introduction of an enhanced non-linear control/modulator topology. Although the non-linear controller is theoretically interesting, the method proves to suffer from various

  2. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes.

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D; Baughman, Ray H; Lee, Hong H; Kang, Tae June; Kim, Yong Hyup

    2016-02-03

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.

  3. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes.

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D; Baughman, Ray H; Lee, Hong H; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  4. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  5. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-02-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m-2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.

  6. Functional carbons and carbon nanohybrids for the catalytic conversion of biomass to renewable chemicals in the condensed phase

    Energy Technology Data Exchange (ETDEWEB)

    Matthiesen, John; Hoff, Thomas; Liu, Chi; Pueschel, Charles; Rao, Radhika; Tessonnier, Jean-Philippe

    2014-06-01

    The production of chemicals from lignocellulosic biomass provides opportunities to synthesize chemicals with new functionalities and grow a more sustainable chemical industry. However, new challenges emerge as research transitions from petrochemistry to biorenewable chemistry. Compared to petrochemisty, the selective conversion of biomass-derived carbohydrates requires most catalytic reactions to take place at low temperatures (< 300°C) and in the condensed phase to prevent reactants and products from degrading. The stability of heterogeneous catalysts in liquid water above the normal boiling point represents one of the major challenges to overcome. Herein, we review some of the latest advances in the field with an emphasis on the role of carbon materials and carbon nanohybrids in addressing this challenge.

  7. Formation Mechanism of the First Carbon-Carbon Bond and the First Olefin in the Methanol Conversion into Hydrocarbons.

    Science.gov (United States)

    Liu, Yue; Müller, Sebastian; Berger, Daniel; Jelic, Jelena; Reuter, Karsten; Tonigold, Markus; Sanchez-Sanchez, Maricruz; Lercher, Johannes A

    2016-05-01

    The elementary reactions leading to the formation of the first carbon-carbon bond during early stages of the zeolite-catalyzed methanol conversion into hydrocarbons were identified by combining kinetics, spectroscopy, and DFT calculations. The first intermediates containing a C-C bond are acetic acid and methyl acetate, which are formed through carbonylation of methanol or dimethyl ether even in presence of water. A series of acid-catalyzed reactions including acetylation, decarboxylation, aldol condensation, and cracking convert those intermediates into a mixture of surface bounded hydrocarbons, the hydrocarbon pool, as well as into the first olefin leaving the catalyst. This carbonylation based mechanism has an energy barrier of 80 kJ mol(-1) for the formation of the first C-C bond, in line with a broad range of experiments, and significantly lower than the barriers associated with earlier proposed mechanisms. PMID:27037603

  8. Functional carbons and carbon nanohybrids for the catalytic conversion of biomass to renewable chemicals in the condensed phase

    Institute of Scientific and Technical Information of China (English)

    John Matthiesen; Thomas Hoff; Chi Liu; Charles Pueschel; Radhika Rao; Jean-Philippe Tessonnier

    2014-01-01

    The production of chemicals from lignocellulosic biomass provides opportunities to synthesize chemicals with new functionalities and grow a more sustainable chemical industry. However, new challenges emerge as research transitions from petrochemistry to biorenewable chemistry. Com-pared to petrochemisty, the selective conversion of biomass-derived carbohydrates requires most catalytic reactions to take place at low temperatures (<300 °C) and in the condensed phase to pre-vent reactants and products from degrading. The stability of heterogeneous catalysts in liquid water above the normal boiling point represents one of the major challenges to overcome. Herein, we review some of the latest advances in the field with an emphasis on the role of carbon materials and carbon nanohybrids in addressing this challenge.

  9. Direct Conversion of Carbon Fuels in a Molten Carbonate Fuel Cell

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, N J; Fiet, K J; Krueger, R; Jankowski, A F; Cooper, J F

    2004-01-28

    Anodes of elemental carbon may be discharged in a galvanic cell using a molten carbonate electrolyte, a nickel-foam anode-current collector, and a porous nickel air cathode to achieve power densities of 40-100 mW/cm{sup 2}. We report cell and anode polarization, surface area, primary particle size and a crystallization index for nine particulate carbon samples derived from fuel oil, methane, coal, charred biological material and petroleum coke. At 800 C, current densities of 50-125 mA/cm{sup 2} were measured at a representative cell voltage of 0.8 V. Power densities for cells with two carbon-anode materials were found to be nearly the same on scales of 2.8- and 60 cm{sup 2} active area. Constant current operation of a small cell was accompanied by constant voltage during multiple tests of 10-30 hour duration. Cell voltage fell off after the carbon inventory was consumed. Three different cathode structures are compared, indicating that an LLNL fabricated porous nickel electrode with <10 {micro}m pores provides improved rates compared with nickel foam with 100-300 {micro}m pores. Petroleum coke containing substantial sulfur and ash discharges at a slightly lower rate than purified petroleum coke. The sulfur leads to degradation of the anode current collector over time. A conceptual model for electrochemical reactivity of carbon is presented which indicates the importance of (1) bulk lattice disorder, which continually provides surface reactive sites during anodic dissolution and (2) electrical conductivity, which lowers the ohmic component of anode polarization.

  10. Effect of carbon monoxide, hydrogen and sulfate on thermophilic (55°C) hydrogenogenic carbon monoxide conversion in two anaerobic bioreactor sludges

    NARCIS (Netherlands)

    Sipma, J.; Meulepas, R.J.W.; Stams, A.J.M.; Lettinga, G.; Lens, P.N.L.

    2004-01-01

    The conversion routes of carbon monoxide (CO) at 55°C by full-scale grown anaerobic sludges treating paper mill and distillery wastewater were elucidated. Inhibition experiments with 2-bromoethanesulfonate (BES) and vancomycin showed that CO conversion was performed by a hydrogenogenic population an

  11. Carbonic Anhydrase: An Efficient Enzyme with Possible Global Implications

    Directory of Open Access Journals (Sweden)

    Christopher D. Boone

    2013-01-01

    Full Text Available As the global atmospheric emissions of carbon dioxide (CO2 and other greenhouse gases continue to grow to record-setting levels, so do the demands for an efficient and inexpensive carbon sequestration system. Concurrently, the first-world dependence on crude oil and natural gas provokes concerns for long-term availability and emphasizes the need for alternative fuel sources. At the forefront of both of these research areas are a family of enzymes known as the carbonic anhydrases (CAs, which reversibly catalyze the hydration of CO2 into bicarbonate. CAs are among the fastest enzymes known, which have a maximum catalytic efficiency approaching the diffusion limit of 108 M−1s−1. As such, CAs are being utilized in various industrial and research settings to help lower CO2 atmospheric emissions and promote biofuel production. This review will highlight some of the recent accomplishments in these areas along with a discussion on their current limitations.

  12. Soil Organic Carbon Loss and Turnover Resulting from Forest Conversion to Maize Fields in Eastern Thailand

    Institute of Scientific and Technical Information of China (English)

    S. JAIARREE; A. CHIDTHAISONG; N. TANGTHAM; C. POLPRASERT; E. SAROBOL; S. C. TYLER

    2011-01-01

    Soil organic carbon (SOC) content and its stable carbon isotopic composition (within the upper 1 m) were measured to determine the effect of land-use changes from dry evergreen forest to maize fields in eastern Thailand.Digital land cover maps,derived from aerial photography and satellite images for years 1989,1996,and 2002 were used in association with field surveys and farmer interviews to derive land-use history and to assist in study site selection.Conversion from forest to maize cultivation for the duration of 12 years reduced SOC stocks at the rate of 6.97 Mg C ha-1 year-1.Reduction was most pronounced in the top 10 cm soil layer,which was 47% after 12 years of cultivation.Stable carbon isotope data revealed that the main fraction lost was forest-derived C.Generally low input rates of maize-derived C were not sufficient to maintain SOC at the level prior to forest conversion.After 12 years of continuous maize cultivation,the maize-derived C fraction made up about 20% of total SOC (5 Mg ha-1 of the total 25.31 Mg ha-1).

  13. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer.

    Science.gov (United States)

    Inada, Natsumi; Asakawa, Hitoshi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid. PMID:27335733

  14. Perovskite Solar Cells: Influence of Hole Transporting Materials on Power Conversion Efficiency.

    Science.gov (United States)

    Ameen, Sadia; Rub, Malik Abdul; Kosa, Samia A; Alamry, Khalid A; Akhtar, M Shaheer; Shin, Hyung-Shik; Seo, Hyung-Kee; Asiri, Abdullah M; Nazeeruddin, Mohammad Khaja

    2016-01-01

    The recent advances in perovskite solar cells (PSCs) created a tsunami effect in the photovoltaic community. PSCs are newfangled high-performance photovoltaic devices with low cost that are solution processable for large-scale energy production. The power conversion efficiency (PCE) of such devices experienced an unprecedented increase from 3.8 % to a certified value exceeding 20 %, demonstrating exceptional properties of perovskites as solar cell materials. A key advancement in perovskite solar cells, compared with dye-sensitized solar cells, occurred with the replacement of liquid electrolytes with solid-state hole-transporting materials (HTMs) such as 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD), which contributed to enhanced PCE values and improved the cell stability. Following improvements in the perovskite crystallinity to produce a smooth, uniform morphology, the selective and efficient extraction of positive and negative charges in the device dictated the PCE of PSCs. In this Review, we focus mainly on the HTMs responsible for hole transport and extraction in PSCs, which is one of the essential components for efficient devices. Here, we describe the current state-of-the-art in molecular engineering of hole-transporting materials that are used in PSCs and highlight the requisites for market-viability of this technology. Finally, we include an outlook on molecular engineering of new functional HTMs for high efficiency PSCs. PMID:26692567

  15. The development of efficient X-ray conversion material for digital mammography

    International Nuclear Information System (INIS)

    In this study, an experimental method based on theory is used to develop photoconductor that can replace the a-Se currently used as X-ray conversion layer in digital mammography. This is necessary because a-Se produced by the commercial fabrication method, of physical vapor deposition, has exhibited several problems when applied to digital mammography: instability due to crystallization and defect expansion due to high operating voltages, which is called the aging effect. Therefore, our work focused on developing a method of fabricating X-ray conversion films that do not suffer from crystallization and X-ray damage and optimizing the factors affecting the properties of the candidate photoconductors in order to acquire sufficient electrical signals to detect minute calcifications. The photoconductors were initially selected after the requirements for X-ray conversion materials, such as high atomic absorption, density, band-gap energy, work function, and resistivity, were examined. We selected HgI2, PbI2, and PbO because of their basic properties. Next, we experimentally investigated the performance of film samples fabricated by sedimentation and screen printing instead of physical vapor deposition. The structure of the X-ray conversion films (e.g., the thickness, electrodes, and blocking layer) were optimized for the application of a relatively low voltage to the X-ray conversion layer. The performance of the films were morphologically and electrically evaluated under mammography X-ray exposure conditions, and compared with those of a-Se films produced by physical vapor deposition. PbO appeared to be the most suitable alternative material because its electrical properties, such as the dark current, sensitivity, and signal-to-noise ratio (SNR), did not reveal the X-ray damage problem, and thus were maintained after repeated exposure to X-rays. Although PbO showed low sensitivity to X-ray exposure, its SNR was superior to that of the other materials, which is expected

  16. Enhanced conversion efficiency in nanocrystalline solar cells using optically functional patterns

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yang Doo; Park, Sang Jun [Department of Materials and Science Engineering, Korea University, 5-1 Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Jang, Eunseok [Photovoltaic Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Oh, Kyoung Suk [KIER-UNIST Advanced Center for Energy, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Cho, Jun-Sik, E-mail: jscho@kier.re.kr [Photovoltaic Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials and Science Engineering, Korea University, 5-1 Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of)

    2015-07-31

    The lower conversion efficiency of nanocrystalline silicon (nc-Si:H) solar cells is a result of its lower photon absorption capability of nc-Si:H. To increase photon absorption of nc-Si:H, the Ag substrates were fabricated with optically functional patterns. Two types of patterns, with random and regular structures, were formed by direct imprint technology. Owing to these optically functional patterns, the scattering of reflected light at the surface of the patterned Ag was enhanced and the optical path became longer. Thus, a greater amount of photons was absorbed by the nc-Si:H layer. Compared to flat Ag (without a surface pattern), the light absorption value of the nc-Si:H layer with a random structure pattern was increased at wavelengths ranging from 600 to 1100 nm. In the case of the regular patterned Ag, the light absorption value of the nc-Si:H layer was higher than the flat Ag at 300 to 1100 nm. Subsequently, nc-Si:H solar cells constructed on the optically functional pattern exhibit a 15.7% higher J{sub sc} value and a 19.5% higher overall conversion efficiency, compared to an identical solar cell on flat Ag. - Highlights: • Optically functional patterns were fabricated by direct printing technique. • The light absorption of solar cells was increased by the patterned Ag substrate. • Current density of solar cells on patterned Ag increased by approximately 15.7%. • The efficiency of solar cells on patterned Ag increased by 19.5%.

  17. Enhanced conversion efficiency in nanocrystalline solar cells using optically functional patterns

    International Nuclear Information System (INIS)

    The lower conversion efficiency of nanocrystalline silicon (nc-Si:H) solar cells is a result of its lower photon absorption capability of nc-Si:H. To increase photon absorption of nc-Si:H, the Ag substrates were fabricated with optically functional patterns. Two types of patterns, with random and regular structures, were formed by direct imprint technology. Owing to these optically functional patterns, the scattering of reflected light at the surface of the patterned Ag was enhanced and the optical path became longer. Thus, a greater amount of photons was absorbed by the nc-Si:H layer. Compared to flat Ag (without a surface pattern), the light absorption value of the nc-Si:H layer with a random structure pattern was increased at wavelengths ranging from 600 to 1100 nm. In the case of the regular patterned Ag, the light absorption value of the nc-Si:H layer was higher than the flat Ag at 300 to 1100 nm. Subsequently, nc-Si:H solar cells constructed on the optically functional pattern exhibit a 15.7% higher Jsc value and a 19.5% higher overall conversion efficiency, compared to an identical solar cell on flat Ag. - Highlights: • Optically functional patterns were fabricated by direct printing technique. • The light absorption of solar cells was increased by the patterned Ag substrate. • Current density of solar cells on patterned Ag increased by approximately 15.7%. • The efficiency of solar cells on patterned Ag increased by 19.5%

  18. Phosphorus-assisted biomass thermal conversion: reducing carbon loss and improving biochar stability.

    Science.gov (United States)

    Zhao, Ling; Cao, Xinde; Zheng, Wei; Kan, Yue

    2014-01-01

    There is often over 50% carbon loss during the thermal conversion of biomass into biochar, leading to it controversy for the biochar formation as a carbon sequestration strategy. Sometimes the biochar also seems not to be stable enough due to physical, chemical, and biological reactions in soils. In this study, three phosphorus-bearing materials, H3PO4, phosphate rock tailing (PRT), and triple superphosphate (TSP), were used as additives to wheat straw with a ratio of 1: 0.4-0.8 for biochar production at 500°C, aiming to alleviate carbon loss during pyrolysis and to increase biochar-C stabilization. All these additives remarkably increased the biochar yield from 31.7% (unmodified biochar) to 46.9%-56.9% (modified biochars). Carbon loss during pyrolysis was reduced from 51.7% to 35.5%-47.7%. Thermogravimetric analysis curves showed that the additives had no effect on thermal stability of biochar but did enhance its oxidative stability. Microbial mineralization was obviously reduced in the modified biochar, especially in the TSP-BC, in which the total CO2 emission during 60-d incubation was reduced by 67.8%, compared to the unmodified biochar. Enhancement of carbon retention and biochar stability was probably due to the formation of meta-phosphate or C-O-PO3, which could either form a physical layer to hinder the contact of C with O2 and bacteria, or occupy the active sites of the C band. Our results indicate that pre-treating biomass with phosphors-bearing materials is effective for reducing carbon loss during pyrolysis and for increasing biochar stabilization, which provides a novel method by which biochar can be designed to improve the carbon sequestration capacity. PMID:25531111

  19. Apparatus and method for enabling quantum-defect-limited conversion efficiency in cladding-pumped Raman fiber lasers

    Energy Technology Data Exchange (ETDEWEB)

    Heebner, John E.; Sridharan, Arun K.; Dawson, Jay Walter; Messerly, Michael J.; Pax, Paul H.

    2016-09-20

    Cladding-pumped Raman fiber lasers and amplifiers provide high-efficiency conversion efficiency at high brightness enhancement. Differential loss is applied to both single-pass configurations appropriate for pulsed amplification and laser oscillator configurations applied to high average power cw source generation.

  20. Blending Influence on the Conversion Efficiency of the Cogasification Process of Corn Stover and Coal

    Directory of Open Access Journals (Sweden)

    Anthony Ike Anukam

    2016-01-01

    Full Text Available Characterizations of biomass and coal were undertaken in order to compare their properties and determine the combustion characteristics of both feedstocks. The study was also intended to establish whether the biomass (corn stover used for this study is a suitable feedstock for blending with coal for the purpose of cogasification based on composition and properties. Proximate and ultimate analyses as well as energy value of both samples including their blends were undertaken and results showed that corn stover is a biomass material well suited for blending with coal for the purpose of cogasification, given its high volatile matter content which was measured and found to be 75.3% and its low ash content of 3.3% including its moderate calorific value of 16.1%. The results of the compositional analyses of both pure and blended samples of corn stover and coal were used to conduct computer simulation of the cogasification processes in order to establish the best blend that would result in optimum cogasification efficiency under standard gasifier operating conditions. The final result of the cogasification simulation process indicated that 90% corn stover/10% coal resulted in a maximum efficiency of about 58% because conversion was efficiently achieved at a temperature that is intermediate to that of coal and corn stover independently.

  1. Stabilized Conversion Efficiency and Dye-Sensitized Solar Cells from Beta vulgaris Pigment

    Directory of Open Access Journals (Sweden)

    Susana Vargas

    2013-02-01

    Full Text Available Dye-Sensitized Solar Cells (DSSCs, based on TiO2 and assembled using a dye from Beta vulgaris extract (BVE with Tetraethylorthosilicate (TEOS, are reported. The dye BVE/TEOS increased its UV resistance, rendering an increase in the cell lifetime; the performance of these solar cells was compared to those prepared with BVE without TEOS. The efficiency η for the solar energy conversion was, for BVE and BVE/TEOS, of 0.89% ± 0.006% and 0.68% ± 0.006% with a current density Jsc of 2.71 ± 0.003 mA/cm2 and 2.08 ± 0.003 mA/cm2, respectively, using in both cases an irradiation of 100 mW/cm2 at 25 °C. The efficiency of the BVE solar cell dropped from 0.9 ± 0.006 to 0.85 ± 0.006 after 72 h of operation, whereas for the BVE/TEOS, the efficiency remained practically constant in the same period of time.

  2. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Science.gov (United States)

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Zeng, Hui; Fang, Jingyun

    2013-01-01

    Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC) dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008) from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR), shrubland (SH), as well as in evergreen coniferous (EC), deciduous coniferous (DC) and deciduous broadleaved forest (DB), to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China. PMID:24058408

  3. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Directory of Open Access Journals (Sweden)

    Wei Wang

    Full Text Available Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008 from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR, shrubland (SH, as well as in evergreen coniferous (EC, deciduous coniferous (DC and deciduous broadleaved forest (DB, to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  4. Zero Waste and Conversion Efficiencies of Various Technologies for Disposal of Municipal Solid Waste

    Institute of Scientific and Technical Information of China (English)

    Zhang Wenyang

    2005-01-01

    Zero waste is a philosophy and a design principle of dealing with our waste stream for the 21st century. After reviewing the available information, the goal of zero waste from landfill is considered to be unachievable by using known and proven methods and approaches. The comparison of various technologies shows that the conversion efficiencies depend upon the type of system chosen for processing residual waste, and the best overall diversion rate of waste management system that can be achieved is about 71%. The maximum achievable overall diversion rate can be increased to approximate 92% if current environmental regulations to permit the routine use of the bottom ash or char for advanced thermal technologies.

  5. Efficient Conversion of Inulin to Inulooligosaccharides through Endoinulinase from Aspergillus niger.

    Science.gov (United States)

    Xu, Yanbing; Zheng, Zhaojuan; Xu, Qianqian; Yong, Qiang; Ouyang, Jia

    2016-03-30

    Inulooligosaccharides (IOS) represent an important class of oligosaccharides at industrial scale. An efficient conversion of inulin to IOS through endoinulinase from Aspergillus niger is presented. A 1482 bp codon optimized gene fragment encoding endoinulinase from A. niger DSM 2466 was cloned into pPIC9K vector and was transformed into Pichia pastoris KM71. Maximum activity of the recombinant endoinulinase, 858 U/mL, was obtained at 120 h of the high cell density fermentation process. The optimal conditions for inulin hydrolysis using the recombinant endoinulinase were investigated. IOS were harvested with a high concentration of 365.1 g/L and high yield up to 91.3%. IOS with different degrees of polymerization (DP, mainly DP 3-6) were distributed in the final reaction products.

  6. Methods of Measuring Energy Conversion Efficiency in Dye-sensitized Solar Cells

    Science.gov (United States)

    Koide, Naoki; Chiba, Yasuo; Han, Liyuan

    2005-06-01

    The current-voltage characteristics of dye-sensitized solar cells (DSCs) were measured and compared with those of crystalline silicon solar cells. It was found that the energy conversion efficiency of DSCs is dependent on voltage sweep direction and sampling delay time (Td). Measurement of the transient photocurrent revealed that this dependence is due to the longer time constant of DSCs. This dependence was also confirmed in a simulation of current-voltage curves based on an equivalent circuit model of DSCs. Analysis of the current-voltage characteristics of polymer-based bulk heterojunction solar cells (BHSCs) and simulated measurements showed that the longer time constant is due to slow movement of ions in the electrolyte. To improve accuracy, the I-V measurement should be carried out from short circuit to open circuit with Td of 100 ms or longer.

  7. Efficient Conversion of Inulin to Inulooligosaccharides through Endoinulinase from Aspergillus niger.

    Science.gov (United States)

    Xu, Yanbing; Zheng, Zhaojuan; Xu, Qianqian; Yong, Qiang; Ouyang, Jia

    2016-03-30

    Inulooligosaccharides (IOS) represent an important class of oligosaccharides at industrial scale. An efficient conversion of inulin to IOS through endoinulinase from Aspergillus niger is presented. A 1482 bp codon optimized gene fragment encoding endoinulinase from A. niger DSM 2466 was cloned into pPIC9K vector and was transformed into Pichia pastoris KM71. Maximum activity of the recombinant endoinulinase, 858 U/mL, was obtained at 120 h of the high cell density fermentation process. The optimal conditions for inulin hydrolysis using the recombinant endoinulinase were investigated. IOS were harvested with a high concentration of 365.1 g/L and high yield up to 91.3%. IOS with different degrees of polymerization (DP, mainly DP 3-6) were distributed in the final reaction products. PMID:26961750

  8. Enhanced Conversion Efficiency of Cu(In,Ga)Se2 Solar Cells via Electrochemical Passivation Treatment.

    Science.gov (United States)

    Tsai, Hung-Wei; Thomas, Stuart R; Chen, Chia-Wei; Wang, Yi-Chung; Tsai, Hsu-Sheng; Yen, Yu-Ting; Hsu, Cheng-Hung; Tsai, Wen-Chi; Wang, Zhiming M; Chueh, Yu-Lun

    2016-03-01

    Defect control in Cu(In,Ga)Se2 (CIGS) materials, no matter what the defect type or density, is a significant issue, correlating directly to PV performance. These defects act as recombination centers and can be briefly categorized into interface recombination and Shockley-Read-Hall (SRH) recombination, both of which can lead to reduced PV performance. Here, we introduce an electrochemical passivation treatment for CIGS films that can lower the oxygen concentration at the CIGS surface as observed by X-ray photoelectron spectrometer analysis. Temperature-dependent J-V characteristics of CIGS solar cells reveal that interface recombination is suppressed and an improved rollover condition can be achieved following our electrochemical treatment. As a result, the surface defects are passivated, and the power conversion efficiency performance of the solar cell devices can be enhanced from 4.73 to 7.75%.

  9. Efficient catalytic system for the conversion of fructose into 5-ethoxymethylfurfural.

    Science.gov (United States)

    Wang, Hongliang; Deng, Tiansheng; Wang, Yingxiong; Qi, Yongqin; Hou, Xianglin; Zhu, Yulei

    2013-05-01

    DMSO can improve the selectivity of 5-hydroxymethylfurfural (HMF) in the conversion of carbohydrates. However, one of the bottlenecks in its application is product separation. Thus a one-pot synthesis of 5-ethoxymethylfurfural (EMF) rather than HMF from fructose in ethanol-DMSO was investigated. Phosphotungstic acid was used as an effective catalyst. The yield of EMF can be reached as high as 64% in the mixed solvent system of DMSO and ethanol within 130 min at 140 °C. Ethyl levulinate (LAE) was detected as the main by-product, the yield of which increased with the reaction time, temperature and the amount of catalyst. In addition, the existence of water could significantly reduce the yield of EMF and increased the yield of LAE. Most importantly, it was discovered that EMF could be much more efficiently extracted from the reaction solvent system by some organic solvents than HMF. PMID:23567707

  10. Piezoelectric coupling in energy-harvesting fluttering flexible plates : linear stability analysis and conversion efficiency

    CERN Document Server

    Doare, Olivier

    2011-01-01

    This paper investigates the energy harvested from the flutter of a plate in an axial flow by making use of piezoelectric materials. The equations for fully-coupled linear dynamics of the fluid-solid and electrical systems are derived. The continuous limit is then considered, when the characteristic length of the plate's deformations is large compared to the piezoelectric patches' length. The linear stability analysis of the coupled system is addressed from both a local and global point of view. Piezoelectric energy harvesting adds rigidity and damping on the motion of the flexible plate, and destabilization by dissipation is observed for negative energy waves propagating in the medium. This result is confirmed in the global analysis of fluttering modes of a finite-length plate. It is finally observed that waves or modes destabilized by piezoelectric coupling maximize the energy conversion efficiency.

  11. Efficient frequency conversion by stimulated Raman scattering in a sodium nitrate aqueous solution

    International Nuclear Information System (INIS)

    Frequency conversion of laser beams, based on stimulated Raman scattering (SRS) is an appealing technique for generating radiation at new wavelengths. Here, we investigated experimentally the SRS due to a single pass of a collimated frequency-doubled Nd:YAG laser beam (532 nm) through a saturated aqueous solution of sodium nitrate (NaNO3), filling a 50 cm long cell. These experiments resulted in simultaneous generation of 1st (564 nm) and 2nd (599 nm) Stokes beams, corresponding to the symmetric stretching mode of the nitrate ion, ν1(NO3−), with 40 and 12 mJ/pulse maximal converted energies, equivalent to 12% and 4% efficiencies, respectively, for a 340 mJ/pulse pump energy. The results indicate that the pump and SRS beams were thermally defocused and that four-wave mixing was responsible for the second order Stokes process onset

  12. A Carbon Exergy Tax Evaluation Based on the Efficient Use of Energy Resources: A Case Study

    Directory of Open Access Journals (Sweden)

    Massimo Santarelli

    2000-09-01

    Full Text Available

    An instrument to promote the CO2 emission reductions, taking the Kyoto Protocol goal into account, can be the assignment to energy conversion plants of a monetary charge linked to their specific emission intensity. Once the choice of a charge is defined, the next problem is the choice of a strategy to determine the amount of the imposed charge, named Carbon Tax (CT.

    In this paper an analytical procedure for the Carbon Tax evaluation is proposed and applied. This approach is based on the concept of Efficiency Penalty of the energy system, that represents the evaluation of the cost of the exergy destroyed inside the system and the cost of the exergy rejected in the biosphere with the plant wastes; the Efficiency Penalty term is coupled with the evaluation of the Index of CO2 Emission, which connects the amount of the CO2 emitted by the plant with the Second Law efficiency of the plant itself. The evaluated charge on the CO2 emissions is defined as Carbon Exergy Tax (CET. The procedure is applied here to the analysis of a 700 MW combined plant burning fossil fuels in two different configurations: a typical natural gas fired combined plant, and a coal fired combined plant burning coal in a Pressurised Fluidised Bed Combustor (PFBC.

  13. Designing interfaces of hydrogenase-nanomaterial hybrids for efficient solar conversion.

    Science.gov (United States)

    King, Paul W

    2013-01-01

    The direct conversion of sunlight into biofuels is an intriguing alternative to a continued reliance on fossil fuels. Natural photosynthesis has long been investigated both as a potential solution, and as a model for utilizing solar energy to drive a water-to-fuel cycle. The molecules and organizational structure provide a template to inspire the design of efficient molecular systems for photocatalysis. A clear design strategy is the coordination of molecular interactions that match kinetic rates and energetic levels to control the direction and flow of energy from light harvesting to catalysis. Energy transduction and electron-transfer reactions occur through interfaces formed between complexes of donor-acceptor molecules. Although the structures of several of the key biological complexes have been solved, detailed descriptions of many electron-transfer complexes are lacking, which presents a challenge to designing and engineering biomolecular systems for solar conversion. Alternatively, it is possible to couple the catalytic power of biological enzymes to light harvesting by semiconductor nanomaterials. In these molecules, surface chemistry and structure can be designed using ligands. The passivation effect of the ligand can also dramatically affect the photophysical properties of the semiconductor, and energetics of external charge-transfer. The length, degree of bond saturation (aromaticity), and solvent exposed functional groups of ligands can be manipulated to further tune the interface to control molecular assembly, and complex stability in photocatalytic hybrids. The results of this research show how ligand selection is critical to designing molecular interfaces that promote efficient self-assembly, charge-transfer and photocatalysis. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. PMID:23541891

  14. Power conversion and luminous efficiency performance of nanophosphor quantum dots on color-conversion LEDs for high-quality general lighting

    Science.gov (United States)

    Erdem, Talha; Nizamoglu, Sedat; Demir, Hilmi Volkan

    2012-03-01

    For high-quality general lighting, a white light source is required to exhibit good photometric and colorimetric performance along with a high level of electrical efficiency. For example, a warm white shade is desirable for indoors, corresponding to correlated color temperatures >=4000 K, together with color rendering indices >=90. Additionally, the luminous efficacy of optical radiation (LER) should be high, preferably >=380 lm/Wopt. Conventional white LEDs cannot currently satisfy these requirements simultaneously. On the other hand, color-conversion white LEDs (WLEDs) integrated with quantum dots (QDs) can simultaneously reach such high levels of photometric and colorimetric performance. However, their electrical efficiency performance and limits have been unknown. To understand their potential of luminous efficiency (lm/Welect), we modeled and studied different QD-WLED architectures based on layered QD films and QD blends, all integrated on blue LED chips. The architecture of red, yellow and green emitting QD films (in this order from the chip outwards) is demonstrated to outperform the rest. In this case, for photometrically efficient spectra, the maximum achievable LE is predicted to be 327 lm/Welect. Using a state-of-the-art blue LED reported with a power conversion efficiency (PCE) of 81.3%, the overall WLED PCE is shown to be 69%. To achieve LEs of 100, 150 and 200 lm/Welect, the required minimum quantum efficiencies of the color-converting QDs are found to be 39, 58 and 79%, respectively.

  15. Elevated soil nitrogen pools after conversion of turfgrass to water-efficient residential landscapes

    Science.gov (United States)

    Heavenrich, Hannah; Hall, Sharon J.

    2016-08-01

    As a result of uncertain resource availability and growing populations, city managers are implementing conservation plans that aim to provide services for people while reducing household resource use. For example, in the US, municipalities are incentivizing homeowners to replace their water-intensive turfgrass lawns with water-efficient landscapes consisting of interspersed drought-tolerant shrubs and trees with rock or mulch groundcover (e.g. xeriscapes, rain gardens, water-wise landscapes). While these strategies are likely to reduce water demand, the consequences for other ecosystem services are unclear. Previous studies in controlled, experimental landscapes have shown that conversion from turfgrass to shrubs may lead to high rates of nutrient leaching from soils. However, little is known about the long-term biogeochemical consequences of this increasingly common land cover change across diverse homeowner management practices. We explored the fate of soil nitrogen (N) across a chronosequence of land cover change from turfgrass to water-efficient landscapes in privately owned yards in metropolitan Phoenix, Arizona, in the arid US Southwest. Soil nitrate ({{{{NO}}}3}-–N) pools were four times larger in water-efficient landscapes (25 ± 4 kg {{{{NO}}}3}-–N/ha 0–45 cm depth) compared to turfgrass lawns (6 ± 7 kg {{{{NO}}}3}-–N/ha). Soil {{{{NO}}}3}-–N also varied significantly with time since landscape conversion; the largest pools occurred at 9–13 years after turfgrass removal and declined to levels comparable to turfgrass thereafter. Variation in soil {{{{NO}}}3}-–N with landscape age was strongly influenced by management practices related to soil water availability, including shrub cover, sub-surface plastic sheeting, and irrigation frequency. Our findings show that transitioning from turfgrass to water-efficient residential landscaping can lead to an accumulation of {{{{NO}}}3}-–N that may be lost from the plant rooting zone over time following

  16. Elevated soil nitrogen pools after conversion of turfgrass to water-efficient residential landscapes

    Science.gov (United States)

    Heavenrich, Hannah; Hall, Sharon J.

    2016-08-01

    As a result of uncertain resource availability and growing populations, city managers are implementing conservation plans that aim to provide services for people while reducing household resource use. For example, in the US, municipalities are incentivizing homeowners to replace their water-intensive turfgrass lawns with water-efficient landscapes consisting of interspersed drought-tolerant shrubs and trees with rock or mulch groundcover (e.g. xeriscapes, rain gardens, water-wise landscapes). While these strategies are likely to reduce water demand, the consequences for other ecosystem services are unclear. Previous studies in controlled, experimental landscapes have shown that conversion from turfgrass to shrubs may lead to high rates of nutrient leaching from soils. However, little is known about the long-term biogeochemical consequences of this increasingly common land cover change across diverse homeowner management practices. We explored the fate of soil nitrogen (N) across a chronosequence of land cover change from turfgrass to water-efficient landscapes in privately owned yards in metropolitan Phoenix, Arizona, in the arid US Southwest. Soil nitrate ({{{{NO}}}3}--N) pools were four times larger in water-efficient landscapes (25 ± 4 kg {{{{NO}}}3}--N/ha 0-45 cm depth) compared to turfgrass lawns (6 ± 7 kg {{{{NO}}}3}--N/ha). Soil {{{{NO}}}3}--N also varied significantly with time since landscape conversion; the largest pools occurred at 9-13 years after turfgrass removal and declined to levels comparable to turfgrass thereafter. Variation in soil {{{{NO}}}3}--N with landscape age was strongly influenced by management practices related to soil water availability, including shrub cover, sub-surface plastic sheeting, and irrigation frequency. Our findings show that transitioning from turfgrass to water-efficient residential landscaping can lead to an accumulation of {{{{NO}}}3}--N that may be lost from the plant rooting zone over time following irrigation or

  17. Mediatorless solar energy conversion by covalently bonded thylakoid monolayer on the glassy carbon electrode.

    Science.gov (United States)

    Lee, Jinhwan; Im, Jaekyun; Kim, Sunghyun

    2016-04-01

    Light reactions of photosynthesis that take place in thylakoid membranes found in plants or cyanobacteria are among the most effective ways of utilizing light. Unlike most researches that use photosystem I or photosystem II as conversion units for converting light to electricity, we have developed a simple method in which the thylakoid monolayer was covalently immobilized on the glassy carbon electrode surface. The activity of isolated thylakoid membrane was confirmed by measuring evolving oxygen under illumination. Glassy carbon surfaces were first modified with partial or full monolayers of carboxyphenyl groups by reductive C-C coupling using 4-aminobenzoic acid and aniline and then thylakoid membrane was bioconjugated through the peptide bond between amine residues of thylakoid and carboxyl groups on the surface. Surface properties of modified surfaces were characterized by cyclic voltammetry, contact angle measurements, and electrochemical impedance spectroscopy. Photocurrent of 230 nA cm(-2) was observed when the thylakoid monolayer was formed on the mixed monolayer of 4-carboxylpheny and benzene at applied potential of 0.4V vs. Ag/AgCl. A small photocurrent resulted when the 4-carboxyphenyl full monolayer was used. This work shows the possibility of solar energy conversion by directly employing the whole thylakoid membrane through simple surface modification.

  18. Maximizing the solar to H{sub 2} energy conversion efficiency of outdoor photobioreactors using mixed cultures

    Energy Technology Data Exchange (ETDEWEB)

    Berberoglu, Halil [Mechanical Engineering Department, Cockrell School of Engineering, The University of Texas at Austin - Austin, TX 78712 (United States); Pilon, Laurent [Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science University of California, Los Angeles - Los Angeles, CA 90095 (United States)

    2010-01-15

    A numerical study is presented aiming to maximize the solar to hydrogen energy conversion efficiency of a mixed culture containing microorganisms with different radiation characteristics. The green algae Chlamydomonas reinhardtii CC125 and the purple non-sulfur bacteria Rhodobacter sphearoides ATCC 49419 are chosen for illustration purposes. The previously measured radiation characteristics of each microorganism are used as input parameters in the radiative transport equation for calculating the local spectral incident radiation within a flat panel photobioreactor. The specific hydrogen production rate for each microorganism as a function of the available incident radiation is recovered from data reported in the literature. The results show that for mono-cultures, the solar to H{sub 2} energy conversion efficiency, for all combinations of microorganism concentrations and photobioreactor thicknesses, fall on a single line with respect to the optical thickness of the system. The maximum solar energy conversion efficiency of mono-cultures of C. reinhardtii and R. spaheroides are 0.061 and 0.054%, respectively, corresponding to optical thicknesses of 200 and 16, respectively. Using mixed cultures, a total conversion efficiency of about 0.075% can be achieved corresponding to an increase of about 23% with respect to that of a mono-culture of C. reinhardtii. It has been shown that the choice of microorganism concentrations for maximum solar energy conversion efficiency in mixed cultures is non-trivial and requires careful radiation transfer analysis coupled with H{sub 2} production kinetics taking into account the photobioreactor thickness. (author)

  19. Toward the Development and Deployment of Large-Scale Carbon Dioxide Capture and Conversion Processes

    DEFF Research Database (Denmark)

    Yuan, Zhihong; Eden, Mario R.; Gani, Rafiqul

    2016-01-01

    In light of the depletion of fossil fuels and the increased daily requirements for liquid fuels and chemicals, CO2 should indeed be regarded as a valuable C-1. additional feedstock for sustainable manufacturing of liquid fuels and chemicals. Development and deployment of CO2 capture and chemical...... conversion processes are among the grand challenges faced by today's scientists and engineers. Very few of the reported CO2 capture and conversion technologies have been employed for industrial installations on a large scale, where high-efficiency, cost/energy-effectiveness, and environmental friendliness...... are three keys factors. The CO2 capture technologies from stationary sources and ambient air based on solvents, solid sorbents, and membranes are discussed first. Transforming CO2 to liquid fuels and chemicals, which are presently produced from petroleum, through thermochemical, electrochemical...

  20. Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

    KAUST Repository

    Zhang, Zhonghai

    2013-02-26

    In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

  1. Recovery Act: Integrated DC-DC Conversion for Energy-Efficient Multicore Processors

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, Kenneth L

    2013-03-31

    In this project, we have developed the use of thin-film magnetic materials to improve in energy efficiency of digital computing applications by enabling integrated dc-dc power conversion and management with on-chip power inductors. Integrated voltage regulators also enables fine-grained power management, by providing dynamic scaling of the supply voltage in concert with the clock frequency of synchronous logic to throttle power consumption at periods of low computational demand. The voltage converter generates lower output voltages during periods of low computational performance requirements and higher output voltages during periods of high computational performance requirements. Implementation of integrated power conversion requires high-capacity energy storage devices, which are generally not available in traditional semiconductor processes. We achieve this with integration of thin-film magnetic materials into a conventional complementary metal-oxide-semiconductor (CMOS) process for high-quality on-chip power inductors. This project includes a body of work conducted to develop integrated switch-mode voltage regulators with thin-film magnetic power inductors. Soft-magnetic materials and inductor topologies are selected and optimized, with intent to maximize efficiency and current density of the integrated regulators. A custom integrated circuit (IC) is designed and fabricated in 45-nm CMOS silicon-on-insulator (SOI) to provide the control system and power-train necessary to drive the power inductors, in addition to providing a digital load for the converter. A silicon interposer is designed and fabricated in collaboration with IBM Research to integrate custom power inductors by chip stacking with the 45-nm CMOS integrated circuit, enabling power conversion with current density greater than 10A/mm2. The concepts and designs developed from this work enable significant improvements in performance-per-watt of future microprocessors in servers, desktops, and mobile

  2. Influences of bulk and surface recombinations on the power conversion efficiency of perovskite solar cells

    Science.gov (United States)

    Xie, Ziang; Sun, Shuren; Yan, Yu; Wang, Wei; Qin, Laixiang; Qin, G. G.

    2016-07-01

    For a novel kind of solar cell (SC) material, it is critical to estimate how far the power conversion efficiencies (PCEs) of the SCs made of it can go. In 2010 Han and Chen proposed the equation for the ultimate efficiency of SCs without considering the carrier recombination η un. η un is capable of estimating the theoretical upper limits of the SC efficiencies and has attracted much attention. However, carrier recombination, which is one of the key factors influencing the PCEs of the SCs, is ignored in the equation for η un. In this paper, we develop a novel equation to calculate the ultimate efficiency for the SCs, η ur, which considers both the bulk and the surface carrier recombinations. The novel equation for η ur can estimate how much the bulk and the surface carrier recombinations influence the PCEs of the SCs. Moreover, with η ur we can estimate how much PCE improvement space can be gained only by reducing the influence of the carrier recombination to the least. The perovskite organometal trihalide SCs have attracted tremendous attention lately. For the planar CH3NH3PbI3 SCs, in the material depth range from 31.25–2000 nm, we apply the equation of η ur to investigate how the bulk and the surface carrier recombinations affect PCE. From a typically reported PCE of 15% for the planar CH3NH3PbI3 SC, using the equation of η ur, it is concluded that by reducing the influence of carrier recombination to the least the improvement of PCE is in the range of 17–30%.

  3. Carbon isotopes and water use efficiency in C4 plants.

    Science.gov (United States)

    Ellsworth, Patrick Z; Cousins, Asaph B

    2016-06-01

    Drought is a major agricultural problem worldwide. Therefore, selection for increased water use efficiency (WUE) in food and biofuel crop species will be an important trait in plant breeding programs. The leaf carbon isotopic composition (δ(13)Cleaf) has been suggested to serve as a rapid and effective high throughput phenotyping method for WUE in both C3 and C4 species. This is because WUE, leaf carbon discrimination (Δ(13)Cleaf), and δ(13)Cleaf are correlated through their relationships with intercellular to ambient CO2 partial pressures (Ci/Ca). However, in C4 plants, changing environmental conditions may influence photosynthetic efficiency (bundle-sheath leakiness) and post-photosynthetic fractionation that will potentially alter the relationship between δ(13)Cleaf and Ci/Ca. Here we discuss how these factors influence the relationship between δ(13)Cleaf and WUE, and the potential of using δ(13)Cleaf as a meaningful proxy for WUE.

  4. Nanoporous Carbon Nitride: A High Efficient Filter for Seawater Desalination

    CERN Document Server

    Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2015-01-01

    The low efficiency of commercially-used reverse osmosis (RO) membranes has been the main obstacle in seawater desalination application. Here, we report the auspicious performance, through molecular dynamics simulations, of a seawater desalination filter based on the recently-synthesized graphene-like carbon nitride (g-C2N) [Nat. Commun., 2015, 6, 6486]. Taking advantage of the inherent nanopores and excellent mechanical properties of g-C2N filter, highly efficient seawater desalination can be achieved by modulating the nanopores under tensile strain. The water permeability can be improved by two orders of magnitude compared to RO membranes, which offers a promising approach to the global water shortage solution.

  5. Tailored exciton diffusion in organic photovoltaic cells for enhanced power conversion efficiency.

    Science.gov (United States)

    Menke, S Matthew; Luhman, Wade A; Holmes, Russell J

    2013-02-01

    Photoconversion in planar-heterojunction organic photovoltaic cells (OPVs) is limited by a short exciton diffusion length (L(D)) that restricts migration to the dissociating electron donor/acceptor interface. Consequently, bulk heterojunctions are often used to realize high efficiency as these structures reduce the distance an exciton must travel to be dissociated. Here, we present an alternative approach that seeks to directly engineer L(D) by optimizing the intermolecular separation and consequently, the photophysical parameters responsible for excitonic energy transfer. By diluting the electron donor boron subphthalocyanine chloride into a wide-energy-gap host material, we optimize the degree of interaction between donor molecules and observe a ~50% increase in L(D). Using this approach, we construct planar-heterojunction OPVs with a power conversion efficiency of (4.4 ± 0.3)%, > 30% larger than the case of optimized devices containing an undiluted donor layer. The underlying correlation between L(D) and the degree of molecular interaction has wide implications for the design of both OPV active materials and device architectures.

  6. The Liquid Droplet Radiator - an Ultralightweight Heat Rejection System for Efficient Energy Conversion in Space

    Science.gov (United States)

    Mattick, A. T.; Hertzberg, A.

    1984-01-01

    A heat rejection system for space is described which uses a recirculating free stream of liquid droplets in place of a solid surface to radiate waste heat. By using sufficiently small droplets ( 100 micron diameter) of low vapor pressure liquids the radiating droplet sheet can be made many times lighter than the lightest solid surface radiators (heat pipes). The liquid droplet radiator (LDR) is less vulnerable to damage by micrometeoroids than solid surface radiators, and may be transported into space far more efficiently. Analyses are presented of LDR applications in thermal and photovoltaic energy conversion which indicate that fluid handling components (droplet generator, droplet collector, heat exchanger, and pump) may comprise most of the radiator system mass. Even the unoptimized models employed yield LDR system masses less than heat pipe radiator system masses, and significant improvement is expected using design approaches that incorporate fluid handling components more efficiently. Technical problems (e.g., spacecraft contamination and electrostatic deflection of droplets) unique to this method of heat rejectioon are discussed and solutions are suggested.

  7. Efficient Eucalypt Cell Wall Deconstruction and Conversion for Sustainable Lignocellulosic Biofuels.

    Science.gov (United States)

    Healey, Adam L; Lee, David J; Furtado, Agnelo; Simmons, Blake A; Henry, Robert J

    2015-01-01

    In order to meet the world's growing energy demand and reduce the impact of greenhouse gas emissions resulting from fossil fuel combustion, renewable plant-based feedstocks for biofuel production must be considered. The first-generation biofuels, derived from starches of edible feedstocks, such as corn, create competition between food and fuel resources, both for the crop itself and the land on which it is grown. As such, biofuel synthesized from non-edible plant biomass (lignocellulose) generated on marginal agricultural land will help to alleviate this competition. Eucalypts, the broadly defined taxa encompassing over 900 species of Eucalyptus, Corymbia, and Angophora are the most widely planted hardwood tree in the world, harvested mainly for timber, pulp and paper, and biomaterial products. More recently, due to their exceptional growth rate and amenability to grow under a wide range of environmental conditions, eucalypts are a leading option for the development of a sustainable lignocellulosic biofuels. However, efficient conversion of woody biomass into fermentable monomeric sugars is largely dependent on pretreatment of the cell wall, whose formation and complexity lend itself toward natural recalcitrance against its efficient deconstruction. A greater understanding of this complexity within the context of various pretreatments will allow the design of new and effective deconstruction processes for bioenergy production. In this review, we present the various pretreatment options for eucalypts, including research into understanding structure and formation of the eucalypt cell wall. PMID:26636077

  8. Tailoring Membrane Nanostructure and Charge Density for High Electrokinetic Energy Conversion Efficiency.

    Science.gov (United States)

    Haldrup, Sofie; Catalano, Jacopo; Hinge, Mogens; Jensen, Grethe V; Pedersen, Jan S; Bentien, Anders

    2016-02-23

    The electrokinetic energy conversion (EKEC) of hydraulic work directly into electrical energy has been investigated in charged polymeric membranes with different pore charge densities and characteristic diameters of the nanoporous network. The membranes were synthesized from blends of nitrocellulose and sulfonated polystyrene (SPS) and were comprehensively characterized with respect to structure, composition, and transport properties. It is shown that the SPS can be used as a sacrificial pore generation medium to tune the pore size and membrane porosity, which in turn highly affects the transport properties of the membranes. Furthermore, it is shown that very high EKEC efficiencies (>35%) are encountered in a rather narrow window of the properties of the nanoporous membrane network, that is, with pore diameters of ca. 10 nm and pore charge densities of 4.6 × 10(2) to 1.5 × 10(3) mol SO3(-) m(-3) for dilute solutions (0.03 M LiCl). The high absolute value of the efficiency combined with the determination of the optimal membrane morphology makes membrane-based EKEC devices a step closer to practical applications and high-performance membrane design less empirical.

  9. Hot-electron-transfer enhancement for the efficient energy conversion of visible light.

    Science.gov (United States)

    Yu, Sungju; Kim, Yong Hwa; Lee, Su Young; Song, Hyeon Don; Yi, Jongheop

    2014-10-13

    Great strides have been made in enhancing solar energy conversion by utilizing plasmonic nanostructures in semiconductors. However, current generation with plasmonic nanostructures is still somewhat inefficient owing to the ultrafast decay of plasmon-induced hot electrons. It is now shown that the ultrafast decay of hot electrons across Au nanoparticles can be significantly reduced by strong coupling with CdS quantum dots and by a Schottky junction with perovskite SrTiO3 nanoparticles. The designed plasmonic nanostructure with three distinct components enables a hot-electron-assisted energy cascade for electron transfer, CdS→Au→SrTiO3, as demonstrated by steady-state and time-resolved photoluminescence spectroscopy. Consequently, hot-electron transfer enabled the efficient production of H2 from water as well as significant electron harvesting under irradiation with visible light of various wavelengths. These findings provide a new approach for overcoming the low efficiency that is typically associated with plasmonic nanostructures. PMID:25169852

  10. Optimization of nanoparticle structure for improved conversion efficiency of dye solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Norani Muti, E-mail: noranimuti-mohamed@petronas.com.my [Centre of Innovative Nanostructure and Nanodevices, Universiti Teknologi PETRONAS, Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Zaine, Siti Nur Azella, E-mail: ct.azella@gmail.com.my [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-10-24

    Heavy dye loading and the ability to contain the light within the thin layer (typically ∼12 μm) are the requirement needed for the photoelectrode material in order to enhance the harvesting efficiency of dye solar cell. This can be realized by optimizing the particle size with desirable crystal structure. The paper reports the investigation on the dependency of the dye loading and light scattering on the properties of nanostructured photoelectrode materials by comparing 4 different samples of TiO{sub 2} in the form of nanoparticles and micron-sized TiO{sub 2} aggregates which composed of nanocrystallites. Their properties were evaluated by using scanning electron microscopy, X-ray diffraction and UVVis spectroscopy while the performance of the fabricated test cells were measured using universal photovoltaic test system (UPTS) under 1000 W/cm{sup 2} intensity of radiation. Nano sized particles provide large surface area which allow for greater dye adsorption but have no ability to retain the incident light in the TiO{sub 2} film. In contrast, micron-sized particles in the form of aggregates can generate light scattering allowing the travelling distance of the light to be extended and increasing the interaction between the photons and dye molecules adsorb on TiO{sub 2}nanocrystallites. This resulted in an improvement in the conversion efficiency of the aggregates that demonstrates the close relation between light scattering effect and the structure of the photolectrode film.

  11. Efficient Eucalypt Cell Wall Deconstruction and Conversion for Sustainable Lignocellulosic Biofuels.

    Science.gov (United States)

    Healey, Adam L; Lee, David J; Furtado, Agnelo; Simmons, Blake A; Henry, Robert J

    2015-01-01

    In order to meet the world's growing energy demand and reduce the impact of greenhouse gas emissions resulting from fossil fuel combustion, renewable plant-based feedstocks for biofuel production must be considered. The first-generation biofuels, derived from starches of edible feedstocks, such as corn, create competition between food and fuel resources, both for the crop itself and the land on which it is grown. As such, biofuel synthesized from non-edible plant biomass (lignocellulose) generated on marginal agricultural land will help to alleviate this competition. Eucalypts, the broadly defined taxa encompassing over 900 species of Eucalyptus, Corymbia, and Angophora are the most widely planted hardwood tree in the world, harvested mainly for timber, pulp and paper, and biomaterial products. More recently, due to their exceptional growth rate and amenability to grow under a wide range of environmental conditions, eucalypts are a leading option for the development of a sustainable lignocellulosic biofuels. However, efficient conversion of woody biomass into fermentable monomeric sugars is largely dependent on pretreatment of the cell wall, whose formation and complexity lend itself toward natural recalcitrance against its efficient deconstruction. A greater understanding of this complexity within the context of various pretreatments will allow the design of new and effective deconstruction processes for bioenergy production. In this review, we present the various pretreatment options for eucalypts, including research into understanding structure and formation of the eucalypt cell wall.

  12. Enhanced power conversion efficiency of dye-sensitized solar cells assisted with phosphor materials

    Science.gov (United States)

    Lee, Yong-Min; Kim, Dong In; Hwang, Ki-Hwan; Nam, Sang Hun; Boo, Jin-Hyo

    2016-07-01

    Theoretically dye-sensitized solar cells (DSSCs) are high efficiency solar cells. However, DSSCs have lower power conversion efficiency (PCE) than silicon based solar cells. In this study, we use scattering layer and phosphor materials, such as ZrO2 and Zn2SiO4:Mn (Green), to enhance the PCE of DSSCs. The scattering layer and phosphor materials were prepared and used as an effective scattering layer on the transparent TiO2 photoelectrode through the doctor blade method. We confirmed that the scattering layer improves the PCE and J sc due to the enhancement of light harvesting by increasing the scattering and absorbance in the visible range. Under sun illumination AM 1.5 conditions, the PCE of the mesoporous TiO2 based DSSCs was 5.18%. The PCE of the DSSCs with ZrO2 scattering layer was 5.61% and Zn2SiO4:Mn as the scattering layer was enhanced to 5.72%. In order to compare the change in optical properties, DSSCs were measured by EQE, reflectance and PCE. At the same time, FE-SEM and XRD were used to confirm the structural changes in each layer. [Figure not available: see fulltext.

  13. Synthesis of carbon black/carbon nitride intercalation compound composite for efficient hydrogen production.

    Science.gov (United States)

    Wu, Zhaochun; Gao, Honglin; Yan, Shicheng; Zou, Zhigang

    2014-08-21

    The photoactivity of g-C3N4 is greatly limited by its high recombination rate of photogenerated carriers. Coupling g-C3N4 with other materials has been demonstrated to be an effective way to facilitate the separation and transport of charge carriers. Herein we report a composite of conductive carbon black and carbon nitride intercalation compound synthesized through facile one-step molten salt method. The as-prepared carbon black/carbon nitride intercalation compound composite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), UV-vis absorption spectrum and photoluminescence spectroscopy (PL). The carbon black nanoparticles, homogeneously dispersed on the surface of carbon nitride intercalation compound, efficiently enhanced separation and transport of photogenerated carriers, thus improving the visible-light photocatalytic activity. The composite of 0.5 wt% carbon black and carbon nitride intercalation compound exhibited a H2 production rate of 68.9 μmol h(-1), which is about 3.2 times higher than hydrogen production on pristine carbon nitride intercalation compound.

  14. Genetic variation for growth rate, feed conversion efficiency, and disease resistance exists within a farmed population of rainbow trout

    DEFF Research Database (Denmark)

    Henryon, Mark; Jokumsen, Alfred; Berg, Peer;

    2002-01-01

    The objective of this study was to test that additive genetic (co)variation for survival, growth rate, feed conversion efficiency, and resistance to viral haemorrhagic septicaemia (VHS) exists within a farmed population of rainbow trout. Thirty sires and 30 dams were mated by a partly factorial...... on days 52, 76, 96, 123, 157, 185, and 215, and body length on days 52 and 215); feed conversion efficiency between days 52-215, 52-76, 77-96, 97-123, 124-157, 158-185, and 186-215, and VHS resistance. REML estimates of additive genetic variation for the body weights, body lengths, and feed conversion...... efficiencies were obtained by fitting univariate linear (reduced) animal models. Additive genetic variation for VHS resistance was estimated by fitting a Weibull, sire-dam frailty model to time until death of fish challenged with VHS. Genetic correlations were estimated among the body weights, body length...

  15. Effect of post-deposition treatment on energy conversion efficiency of nanostructured CdS/Cu2S thin films

    International Nuclear Information System (INIS)

    In the present manuscript we report about synthesis of nanostructured CdS/Cu2S thin films by economically viable soft chemical route and effect of post deposition treatments such as annealing in air and swift heavy ion irradiation on solar energy conversion efficiency of the heterojunction device. These as grown, annealed and irradiated thin films are characterized for structural, morphological, optical and I-V properties. X-ray diffraction pattern (XRD) represents structural as well as crystallite modifications, atomic force microscopy (AFM) shows improvement in surface appearance of the materials. The solar energy conversion efficiency calculated from I-V exhibited increase in conversion efficiency i. e. 0.09, 0.24 and 0.48 % for as grown, annealed and SHI irradiated thin films.

  16. Evaluation of Powdered Activated Carbon Efficiency in Removal of Dissolved Organic Carbon inWater Treatment

    OpenAIRE

    G.R Bonyadi nejad; R Hadian; M Saadani; B Jaberian; M.M Amin; A Khodabakhshi

    2010-01-01

    "n "nBackgrounds and Objectives: Powdered Activated$ carbon is known as a suitable absorbent for organic materials. The aim of this research is evaluation of Powdered Activated-Carbon (PAC) efficiency in removal of Dissolved Organic Carbon (DOC) in water treatment in Isfahan."nMaterials and Methods : The increase of PAC for DOC reduction has done in three paths in the Isfahan water treatment plant (WTP). These paths including: 1) Intake up to entrance of WTP 2) Intake to exit ofWTP 3) Between...

  17. Efficient textured colour conversion layer of a down-converted white organic light-emitting diode by transfer imprinting

    International Nuclear Information System (INIS)

    In this paper, we demonstrated an efficient textured colour conversion layer (CCL) of a down-converted white organic light-emitting diode (WOLED), which was fabricated by a very simple transfer imprinting method based on silicon wafer. The textured CCL not only helped to extract wave-guided light in the device, but also had an outstanding performance in enhancing the colour conversion rate, which was 1.75 times greater than that of flat CCL. Compared to flat CCL, the lower-doped textured CCL produced better white emission and higher efficiency simultaneously. Moreover, the WOLED with textured CCL also exhibited good colour stability at various voltages. (paper)

  18. Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO{sub 2} slurry-based photoanode

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jiaoping; Chen, Zexiang, E-mail: zxchen@uestc.edu.cn; Li, Jun; Wang, Yan, E-mail: zxchen@uestc.edu.cn; Zhang, Jijun; Li, Hai [School of Opto-electronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Xiang, Dong [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-02-15

    A new titanium dioxide (TiO{sub 2}) slurry formulation is herein reported for the fabrication of TiO{sub 2} photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO{sub 2} photoanode featured a highly uniform mesoporous structure with well-dispersed TiO{sub 2} nanoparticles. The energy conversion efficiency of the resulting TiO{sub 2} slurry-based DSSC was ∼63% higher than that achieved by a DSSC prepared using a commercial TiO{sub 2} slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs) into the TiO{sub 2} slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO{sub 2} photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ∼0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO{sub 2} slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.

  19. A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells: Multijunction Tandem, Lower Dimensional, Photonic Up/Down Conversion and Plasmonic Nanometallic Structures

    Directory of Open Access Journals (Sweden)

    Katsuaki Tanabe

    2009-07-01

    Full Text Available Solar cells are a promising renewable, carbon-free electric energy resource to address the fossil fuel shortage and global warming. Energy conversion efficiencies around 40% have been recently achieved in laboratories using III-V semiconductor compounds as photovoltaic materials. This article reviews the efforts and accomplishments made for higher efficiency III-V semiconductor compound solar cells, specifically with multijunction tandem, lower-dimensional, photonic up/down conversion, and plasmonic metallic structures. Technological strategies for further performance improvement from the most efficient (AlInGaP/(InGaAs/Ge triple-junction cells including the search for 1.0 eV bandgap semiconductors are discussed. Lower-dimensional systems such as quantum well and dot structures are being intensively studied to realize multiple exciton generation and multiple photon absorption to break the conventional efficiency limit. Implementation of plasmonic metallic nanostructures manipulating photonic energy flow directions to enhance sunlight absorption in thin photovoltaic semiconductor materials is also emerging.

  20. Analysis of energy efficiency and carbon dioxide reduction in the Chinese pulp and paper industry

    International Nuclear Information System (INIS)

    Pulp and paper production, an energy-intensive process, is among the main light industries contributing to energy saving and pollution emission reduction in China. The improvement of energy efficiency is essential for energy consumption and sustainable development. This study analyzes the negative factors in the pulp and paper sector by calculating energy efficiency from the lengthways time and investigating the gap between China and foreign countries through a horizontal comparison. Accordingly, energy efficiency has increased in the Chinese pulp and paper industry with years of efforts, but its transformation remains unclear. Furthermore, the energy-saving potential, energy cost saving, and carbon dioxide emission reduction in the pulp and paper industry are evaluated according to the Twelfth Five-year Plan (2011–2015). The results show that the pulp and paper industry has further capabilities for energy-saving and carbon dioxide emission reduction by improving energy efficiency in China, resulting in great economic benefit. In brief, new technology and energy structure adjustment are long-term strategies for energy conversation, with changes in the scale of mills expected to provide huge opportunities to improve energy efficiency in China within a short period. - Highlights: • Energy efficiency in pulp and paper industry changes markedly from 1985 to 2010. • This paper will identify better opportunities for energy conservation in China. • This paper will also confirm better opportunities for CO2 emission mitigation. • The negative factors do exist in the pulp and paper sector. • Energy efficient policies are suggested, especially in short term

  1. Energy efficiency and carbon trading potential in Malaysia

    International Nuclear Information System (INIS)

    The damage inflicted by global warming is happening far faster than any experts have predicted or anticipated. Since the Kyoto Protocol was signed in 1997 to fight global warming through reducing global greenhouse gases (GHGs) emission, the world climate pattern has worsened at an accelerated rate beyond expectation. While developed countries sanctioned by the protocol are committed to achieve their GHG emission targets, developing nations play similar roles on a voluntary basis. Since almost all of the GHGs emissions come from energy sector, it is obvious that energy policy and related regulatory frameworks play imperative roles in realizing the Kyoto Protocol objectives. With carbon dioxide (CO2) touted as the main remedy in the GHGs emissions, it is only reasonable that carbon trading becomes the essential element in the Protocol. Recently a milestone is marked in the Kyoto Protocol with the 2009 Climate Summit in Copenhagen, Denmark, with all participating countries further committed themselves in fulfilling the protocol's obligations before the commitment period due in 2012. It is worthwhile to review the various energy efficiency efforts and carbon trading potential in Malaysia, a country which although does not bear any obligation, has ratified and lauded the cause of the protocol. Malaysia as a developing nation is seen as a direct beneficiary from carbon trading and in this paper, how the country energy policies have evolved over the years with concerted efforts from the government to minimize its carbon footprint through numerous energy efficiency implementations are discussed in length. The impact from the 2009 Climate Summit on Malaysia is also briefed. (author)

  2. A thermogravimetric analysis (TGA) method to determine the catalytic conversion of cellulose from carbon-supported hydrogenolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Glauco F. [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil); Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Ramos, Luiz A. [Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Barrett, Dean H. [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil); Curvelo, Antonio Aprígio S. [Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6179, 13083-970 Campinas, SP (Brazil); Rodella, Cristiane B., E-mail: cristiane.rodella@lnls.br [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil)

    2015-09-20

    Graphical abstract: - Highlights: • A new method to determine the catalytic conversion of cellulose using TGA has been developed. • TGA is able to differentiate between carbon from cellulose and carbon from the catalyst. • Building an analytical curve from TGA results enables the accurate determination of cellulose conversion. - Abstract: The ability to determine the quantity of solid reactant that has been transformed after a catalytic reaction is fundamental in accurately defining the conversion of the catalyst. This quantity is also central when investigating the recyclability of a solid catalyst as well as process control in an industrial catalytic application. However, when using carbon-supported catalysts for the conversion of cellulose this value is difficult to obtain using only a gravimetric method. The difficulty lies in weighing errors caused by loss of the solid mixture (catalyst and non-converted cellulose) after the reaction and/or moisture adsorption by the substrate. These errors are then propagated into the conversion calculation giving erroneous results. Thus, a quantitative method using thermogravimetric analysis (TGA) has been developed to determine the quantity of cellulose after a catalytic reaction by using a tungsten carbide catalyst supported on activated carbon. Stepped separation of TGA curves was used for quantitative analysis where three thermal events were identified: moisture loss, cellulose decomposition and CO/CO{sub 2} formation. An analytical curve was derived and applied to quantify the residual cellulose after catalytic reactions which were performed at various temperatures and reaction times. The catalytic conversion was calculated and compared to the standard gravimetric method. Results showed that catalytic cellulose conversion can be determined using TGA and exhibits lower uncertainty (±2%) when compared to gravimetric determination (±5%). Therefore, it is a simple and relatively inexpensive method to determine

  3. Zinc oxide nanorod assisted rapid single-step process for the conversion of electrospun poly(acrylonitrile) nanofibers to carbon nanofibers with a high graphitic content

    Science.gov (United States)

    Nain, Ratyakshi; Singh, Dhirendra; Jassal, Manjeet; Agrawal, Ashwini K.

    2016-02-01

    The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for immobilization of polymer chains and assisted in uniform heat distribution. This facilitated rapid and efficient conversion of the polymer structure to the ladder, and subsequently, the graphitized structure. At the end of the process, the ZnO nanorods were found to completely separate from the carbonized fibers yielding pure carbon nanofibers with a high graphitic content and surface area. The approach could be used to eliminate the slow, energy intensive stabilization step and achieve fast conversion of randomly laid carbon nanofiber webs in a single step to carbon nanofibers without the application of external tension or internal templates usually employed to achieve a high graphitic content in such systems.The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for

  4. High Efficiency Wavelength Conversion of 40 Gbps Signals at 1550 nm in SOI Nano-Rib Waveguides Using p-i-n Diodes

    DEFF Research Database (Denmark)

    Gajda, Andrzej; Da Ros, Francesco; Vukovic, Dragana;

    2013-01-01

    We demonstrate enhancement of FWM wavelength conversion of a 40 Gbps signal in a reverse-biased p-i-n junction silicon waveguide. A conversion efficiency of −4.6 dB enables a conversion power penalty as low as 0.2 dB.......We demonstrate enhancement of FWM wavelength conversion of a 40 Gbps signal in a reverse-biased p-i-n junction silicon waveguide. A conversion efficiency of −4.6 dB enables a conversion power penalty as low as 0.2 dB....

  5. Carbon and nutrient use efficiencies optimally balance stoichiometric imbalances

    Science.gov (United States)

    Manzoni, Stefano; Čapek, Petr; Lindahl, Björn; Mooshammer, Maria; Richter, Andreas; Šantrůčková, Hana

    2016-04-01

    Decomposer organisms face large stoichiometric imbalances because their food is generally poor in nutrients compared to the decomposer cellular composition. The presence of excess carbon (C) requires adaptations to utilize nutrients effectively while disposing of or investing excess C. As food composition changes, these adaptations lead to variable C- and nutrient-use efficiencies (defined as the ratios of C and nutrients used for growth over the amounts consumed). For organisms to be ecologically competitive, these changes in efficiencies with resource stoichiometry have to balance advantages and disadvantages in an optimal way. We hypothesize that efficiencies are varied so that community growth rate is optimized along stoichiometric gradients of their resources. Building from previous theories, we predict that maximum growth is achieved when C and nutrients are co-limiting, so that the maximum C-use efficiency is reached, and nutrient release is minimized. This optimality principle is expected to be applicable across terrestrial-aquatic borders, to various elements, and at different trophic levels. While the growth rate maximization hypothesis has been evaluated for consumers and predators, in this contribution we test it for terrestrial and aquatic decomposers degrading resources across wide stoichiometry gradients. The optimality hypothesis predicts constant efficiencies at low substrate C:N and C:P, whereas above a stoichiometric threshold, C-use efficiency declines and nitrogen- and phosphorus-use efficiencies increase up to one. Thus, high resource C:N and C:P lead to low C-use efficiency, but effective retention of nitrogen and phosphorus. Predictions are broadly consistent with efficiency trends in decomposer communities across terrestrial and aquatic ecosystems.

  6. Impregnation of Catalytic Metals in Single-Walled Carbon Nanotubes for Toxic Gas Conversion in Life Support System

    Science.gov (United States)

    Li, Jing; Wignarajah, Kanapathipillai; Cinke, Marty; Partridge, Harry; Fisher, John

    2004-01-01

    Carbon nanotubes (CNTs) possess extraordinary properties such as high surface area, ordered chemical structure that allows functionalization, larger pore volume, and very narrow pore size distribution that have attracted considerable research attention from around the world since their discovery in 1991. The development and characterization of an original and innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches due to the ability to direct the selective uptake of gaseous species based on their controlled pore size, increased adsorptive capacity due to their increased surface area and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. We present our recent investigation of using SWNTs as catalytic supporting materials to impregnate metals, such as rhodium (Rh), palladium (Pd) and other catalysts. A protocol has been developed to oxidize the SWNTs first and then impregnate the Rh in aqueous rhodium chloride solution, according to unique surface properties of SWNTs. The Rh has been successfully impregnated in SWNTs. The Rh-SWNTs have been characterized by various techniques, such as TGA, XPS, TEM, and FTIR. The project is funded by a NASA Research Announcement Grant to find applications of single walled nanocarbons in eliminating toxic gas Contaminant in life support system. This knowledge will be utilized in the development of a prototype SWNT KO, gas purification system that would represent a significant step in the development of high efficiency systems capable of selectively removing specific gaseous for use in regenerative life support system for human exploration missions.

  7. Carbon trading as incentive for conversion to organic agriculture. Case study. Organic peanuts in Tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, F.

    2005-12-15

    In this pilot project, the climate effects of the conversion from conventional to organic cultivation of peanuts are evaluated. We could aim at voluntary carbon credits that do not comply with the CDM (Clean Development Mechanisms) rules, but we try to meet the CDM rules by combining it with a agroforestry component. However, in the example of Tanzania meeting the CDM rules was a problem. The agricultural system in Tanzania consists of a rotation of several years cultivation and several years fallow. This fallow of grass, shrubs and trees could be considered as 'forest'. Taking fallow land into cultivation would then be deforestation, which would make the planting of trees no longer eligible under CDM. This is a shame because the traditional 'slash and burn' system emits a lot of greenhouse gases.

  8. Genetic Modification of Short Rotation Poplar Biomass Feedstock for Efficient Conversion to Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Dinus, R.J.

    2000-08-30

    The Bioenergy Feedstock Development Program, Environmental Sciences Division, Oak Ridge National Laboratory is developing poplars (Populus species and hybrids) as sources of renewable energy, i.e., ethanol. Notable increases in adaptability, volume productivity, and pest/stress resistance have been achieved via classical selection and breeding and intensified cultural practices. Significant advances have also been made in the efficiencies of harvesting and handling systems. Given these and anticipated accomplishments, program leaders are considering shifting some attention to genetically modifying feedstock physical and chemical properties, so as to improve the efficiency with which feedstocks can be converted to ethanol. This report provides an in-depth review and synthesis of opportunities for and feasibilities of genetically modifying feedstock qualities via classical selection and breeding, marker-aided selection and breeding, and genetic transformation. Information was collected by analysis of the literature, with emphasis on that published since 1995, and interviews with prominent scientists, breeders, and growers. Poplar research is well advanced, and literature is abundant. The report therefore primarily reflects advances in poplars, but data from other species, particularly other shortrotation hardwoods, are incorporated to fill gaps. An executive summary and recommendations for research, development, and technology transfer are provided immediately after the table of contents. The first major section of the report describes processes most likely to be used for conversion of poplar biomass to ethanol, the various physical and chemical properties of poplar feedstocks, and how such properties are expected to affect process efficiency. The need is stressed for improved understanding of the impact of change on both overall process and individual process step efficiencies. The second part documents advances in trait measurement instrumentation and methodology

  9. Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

    Science.gov (United States)

    Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

    2016-01-15

    With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes.

  10. Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

    Science.gov (United States)

    Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

    2016-01-15

    With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes. PMID:26712095

  11. Carbon Dioxide Conversion to Valuable Chemical Products over Composite Catalytic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dagle, Robert A.; Hu, Jianli; Jones, Susanne B.; Wilcox, Wayne A.; Frye, John G.; White, J. F.; Jiang, Juyuan; Wang, Yong

    2013-05-01

    Presented is an experimental study on catalytic conversion of carbon dioxide into methanol, ethanol and acetic acid. Catalysts having different catalytic functions were synthesized and combined in different ways to enhance selectivity to desired products. The combined catalyst system possessed the following functions: methanol synthesis, Fischer-Tropsch synthesis, water-gas-shift and hydrogenation. Results showed that the methods of integrating these catalytic functions played important role in achieving desired product selectivity. It was speculated that if methanol synthesis sites were located adjacent to the C-C chain growth sites, the formation rate of C2 oxygenates would be enhanced. The advantage of using high temperature methanol catalyst PdZnAl in the combined catalyst system was demonstrated. In the presence of PdZnAl catalyst, the combined catalyst system was stable at temperature of 380oC. It was observed that, at high temperature, kinetics favored oxygenate formation. Results implied that the process can be intensified by operating at high temperature using Pd-based methanol synthesis catalyst. Steam reforming of the byproduct organics was demonstrated as a means to provide supplemental hydrogen. Preliminary process design, simulation, and economic analysis of the proposed CO2 conversion process were carried out. Economic analysis indicates how ethanol production cost was affected by the price of CO2 and hydrogen.

  12. Modifying woody plants for efficient conversion to liquid and gaseous fuels

    Energy Technology Data Exchange (ETDEWEB)

    Dinus, R.J.; Dimmel, D.R.; Feirer, R.P.; Johnson, M.A.; Malcolm, E.W. (Institute of Paper Science and Technology, Atlanta, GA (USA))

    1990-07-01

    The Short Rotation Woody Crop Program (SRWCP), Department of Energy, is developing woody plant species as sources of renewable energy. Much progress has been made in identifying useful species, and testing site adaptability, stand densities, coppicing abilities, rotation lengths, and harvesting systems. Conventional plant breeding and intensive cultural practices have been used to increase above-ground biomass yields. Given these and foreseeable accomplishments, program leaders are now shifting attention to prospects for altering biomass physical and chemical characteristics, and to ways for improving the efficiency with which biomass can be converted to gaseous and liquid fuels. This report provides a review and synthesis of literature concerning the quantity and quality of such characteristics and constituents, and opportunities for manipulating them via conventional selection and breeding and/or molecular biology. Species now used by SRWCP are emphasized, with supporting information drawn from others as needed. Little information was found on silver maple (Acer saccharinum), but general comparisons (Isenberg 1981) suggest composition and behavior similar to those of the other species. Where possible, conclusions concerning means for and feasibility of manipulation are given, along with expected impacts on conversion efficiency. Information is also provided on relationships to other traits, genotype X environment interactions, and potential trade-offs or limitations. Biomass productivity per se is not addressed, except in terms of effects that may by caused by changes in constituent quality and/or quantity. Such effects are noted to the extent they are known or can be estimated. Likely impacts of changes, however effected, on suitability or other uses, e.g., pulp and paper manufacture, are notes. 311 refs., 4 figs., 9 tabs.

  13. Resource limits and conversion efficiency with implications for climate change and California's energy supply

    Science.gov (United States)

    Croft, Gregory Donald

    on aggregated reserve numbers. Electric power generation consumes 92 percent of U.S. coal production. Natural gas competes with coal as a baseload power generation fuel with similar or slightly better generation efficiency. Fischer-Tropsch synthesis, described in Chapter 2, creates transportation fuel from coal with an efficiency of less than 45 percent. Claims of higher efficiencies are based on waste heat recovery, since this is a highly exothermic process. The yield of liquid fuel as a proportion of the energy content of the coal input is always less than 45 percent. Compressed natural gas can be used for vehicle fuel with efficiency greater than 98 percent. If we view Fischer-Tropsch synthesis as a form of arbitrage between markets for electricity and transportation fuel, coal cannot simultaneously compete with natural gas for both transportation fuel and electric power. This is because Fischer-Tropsch synthesis is a way to turn power generation fuel into transportation fuel with low efficiency, while natural gas can be converted to transportation fuel with much greater efficiency. For this reason, Fischer-Tropsch synthesis will be an uneconomic source of transportation fuel as long as natural gas is economic for power generation. This conclusion holds even without the very high capital cost of coal-to-liquids plants. The Intergovernmental Panel on Climate Change (IPCC) has generated forty carbon production and emissions scenarios, see the IPCC Special Report on Emissions Scenarios (2000). Chapter 4 develops a base-case scenario for global coal production based on the physical multi-cycle Hubbert analysis of historical production data. Areas with large resources but little production history, such as Alaska or Eastern Siberia, can be treated as sensitivities on top of this base case. The value of our approach is that it provides a reality check on the magnitude of carbon emissions in a business-as-usual (BAU) scenario. The resulting base case is significantly

  14. Efficient frequency conversion by stimulated Raman scattering in a sodium nitrate aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ganot, Yuval, E-mail: yuvalga@sapir.ac.il, E-mail: ibar@bgu.ac.il [Department of Engineering, Sapir Academic College, D. N. Hof Ashkelon 79165 (Israel); Bar, Ilana, E-mail: yuvalga@sapir.ac.il, E-mail: ibar@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2015-09-28

    Frequency conversion of laser beams, based on stimulated Raman scattering (SRS) is an appealing technique for generating radiation at new wavelengths. Here, we investigated experimentally the SRS due to a single pass of a collimated frequency-doubled Nd:YAG laser beam (532 nm) through a saturated aqueous solution of sodium nitrate (NaNO{sub 3}), filling a 50 cm long cell. These experiments resulted in simultaneous generation of 1st (564 nm) and 2nd (599 nm) Stokes beams, corresponding to the symmetric stretching mode of the nitrate ion, ν{sub 1}(NO{sub 3}{sup −}), with 40 and 12 mJ/pulse maximal converted energies, equivalent to 12% and 4% efficiencies, respectively, for a 340 mJ/pulse pump energy. The results indicate that the pump and SRS beams were thermally defocused and that four-wave mixing was responsible for the second order Stokes process onset.

  15. Designation of highly efficient catalysts for one pot conversion of glycerol to lactic acid

    Science.gov (United States)

    Tao, Meilin; Dan Zhang; Guan, Hongyu; Huang, Guohui; Wang, Xiaohong

    2016-07-01

    Production of lactic acid from glycerol is a cascade catalytic procedure using multifunctional catalysts combined with oxidative and acidic catalytic sites. Therefore, a series of silver-exchanged phosphomolybdic acid catalysts (AgxH3‑xPMo12O40, x = 1 ~ 3, abbreviated as AgxPMo) was designed and applied in glycerol oxidation with O2 as an oxidant to produce lactic acid (LA) without adding any base. Among all, total silver exchanged phosphomolybdic acid (Ag3PMo) was found to be the most active one with LA selectivity of 93% at 99% conversion under mild conditions of 5 h at 60 °C. The exceptionally high efficiency was contributed to the generation of strong Lewis acid sites, enhanced redox potentials and water-tolerance. More importantly, Ag3PMo was tolerant in crude glycerol from biodiesel production. And the reaction mechanism was also discussed. Meanwhile, Ag3PMo acted as a heterogeneous catalyst for 12 recycles without loss of activity.

  16. Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification.

    Science.gov (United States)

    Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

    2016-01-01

    Prions are formed of misfolded assemblies (PrP(Sc)) of the variably N-glycosylated cellular prion protein (PrP(C)). In infected species, prions replicate by seeding the conversion and polymerization of host PrP(C). Distinct prion strains can be recognized, exhibiting defined PrP(Sc) biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrP(Sc) assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrP(C) glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrP(C) species of interest as substrate. Applying the technique to PrP(C) glycosylation mutants expressing cells revealed that neither PrP(C) nor PrP(Sc) glycoform stoichiometry was instrumental to PrP(Sc) formation and strainness perpetuation. Our study supports the view that strain properties, including PrP(Sc) glycotype are enciphered within PrP(Sc) structural backbone, not in the attached glycans. PMID:27384922

  17. Influence of Titania Dispersivity on the Conversion Efficiency of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Yasuhiro Yamamoto

    2011-01-01

    Full Text Available Titania powder (P25 was dispersed by bead-milling breakdown method, and the dispersivity of TiO2 was controlled by adjusting the mean secondary TiO2 particle size to 45, 56, and 75 nm by changing the dispersion solvent blend ratio of ethanol and terpineol. The transparency of the coated layer increased when the particle size of TiO2 aggregates became smaller than 100 nm. Although the transparency was significantly different according to differences in the size of nanocrystallyne-TiO2 aggregates, the resulting photovoltaic (PV effect of a dye-sensitized solar cell (DSSC was not significantly different between the different aggregate sizes. A double layer structure (transparent TiO2 layer/opaque TiO2 layer was adopted to improve the PV effect, which resulted in an improvement of the photocurrent and conversion efficiency of 13.2% and 11.1%, respectively, from that for the DSSCs with single-layered TiO2 electrodes.

  18. Designation of highly efficient catalysts for one pot conversion of glycerol to lactic acid.

    Science.gov (United States)

    Tao, Meilin; Dan Zhang; Guan, Hongyu; Huang, Guohui; Wang, Xiaohong

    2016-01-01

    Production of lactic acid from glycerol is a cascade catalytic procedure using multifunctional catalysts combined with oxidative and acidic catalytic sites. Therefore, a series of silver-exchanged phosphomolybdic acid catalysts (AgxH3-xPMo12O40, x = 1 ~ 3, abbreviated as AgxPMo) was designed and applied in glycerol oxidation with O2 as an oxidant to produce lactic acid (LA) without adding any base. Among all, total silver exchanged phosphomolybdic acid (Ag3PMo) was found to be the most active one with LA selectivity of 93% at 99% conversion under mild conditions of 5 h at 60 °C. The exceptionally high efficiency was contributed to the generation of strong Lewis acid sites, enhanced redox potentials and water-tolerance. More importantly, Ag3PMo was tolerant in crude glycerol from biodiesel production. And the reaction mechanism was also discussed. Meanwhile, Ag3PMo acted as a heterogeneous catalyst for 12 recycles without loss of activity. PMID:27431610

  19. Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels.

    Science.gov (United States)

    Singh, Meenesh R; Clark, Ezra L; Bell, Alexis T

    2015-11-10

    Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

  20. Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

    Science.gov (United States)

    Singh, Meenesh R.; Clark, Ezra L.; Bell, Alexis T.

    2015-11-01

    Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

  1. Effects of Conversion from Boreal Forest to Arctic Steppe on Soil Communities and Ecosystem Carbon Pools

    Science.gov (United States)

    Han, P. D.; Natali, S.; Schade, J. D.; Zimov, N.; Zimov, S. A.

    2014-12-01

    The end of the Pleistocene marked the extinction of a great variety of arctic megafauna, which, in part, led to the conversion of arctic grasslands to modern Siberian larch forest. This shift may have increased the vulnerability of permafrost to thawing because of changes driven by the vegetation shift; the higher albedo of grassland and low insulation of snow trampled by animals may have decreased soil temperatures and reduced ground thaw in the grassland ecosystem, resulting in protection of organic carbon in thawed soil and permafrost. To test these hypothesized impacts of arctic megafauna, we examined an experimental reintroduction of large mammals in northeast Siberia, initiated in 1988. Pleistocene Park now contains 23 horses, three musk ox, one bison, and several moose in addition to the native fauna. The park is 16 square km with a smaller enclosure (animals spend most of their time and our study was focused. We measured carbon-pools in forested sites (where scat surveys showed low animal use), and grassy sites (which showed higher use), within the park boundaries. We also measured thaw depth and documented the soil invertebrate communities in each ecosystem. There was a substantial difference in number of invertebrates per kg of organic soil between the forest (600 ± 250) and grassland (300 ± 250), though these differences were not statistically significant they suggest faster nutrient turnover in the forest or a greater proportion of decomposition by invertebrates than other decomposers. While thaw depth was deeper in the grassland (60 ± 4 cm) than in the forest (40 ± 6 cm), we did not detect differences in organic layer depth or percent organic matter between grassland and forest. However, soil in the grassland had higher bulk density, and higher carbon stocks in the organic and mineral soil layers. Although deeper thaw depth in the grassland suggests that more carbon is available to microbial decomposers, ongoing temperature monitoring will help

  2. Analysis of efficiency of solar energy conversion by tandem CdxZn1-xTe/Si solar cell

    International Nuclear Information System (INIS)

    In this work efficiency of solar energy conversion by solar cell based on tandem structure CdZnTe/Si is analyzed. It is shown that CdTe-CdZnTe-ZnTe material system is promising for creation of high-performance cascade solar cells

  3. Evaluation of Powdered Activated Carbon Efficiency in Removal of Dissolved Organic Carbon inWater Treatment

    Directory of Open Access Journals (Sweden)

    G.R Bonyadi nejad

    2010-07-01

    Full Text Available "n "nBackgrounds and Objectives: Powdered Activated$ carbon is known as a suitable absorbent for organic materials. The aim of this research is evaluation of Powdered Activated-Carbon (PAC efficiency in removal of Dissolved Organic Carbon (DOC in water treatment in Isfahan."nMaterials and Methods : The increase of PAC for DOC reduction has done in three paths in the Isfahan water treatment plant (WTP. These paths including: 1 Intake up to entrance of WTP 2 Intake to exit ofWTP 3 Between entrance and exit of waterworks. The paths were simulated by the Jar test system. Then DOC and UV254 absorption were analyzed and SUVA parameter for samples and activated-carbon adsorption isotherm was calculated."nResults: The injected PAC doses of 20,40,60,80 and 100 mg/l caused decreasing in DOC and UV254 absorption in every sample in all paths. The average of this decrease, from intake to WTP.s exit (second path was the greatest 69.8± 3.9%and the commonWTP process had capability of removing 35% of DOC. The first path also showed that PAC can reduce 33± 2% DOC of raw water by itself. Activated-carbon absorption results were adhered from Freundlich adsorption isotherm."nConclusion: In the third path therewas lessDOCremoval efficiency than exceptedwhen Activated- Carbon injected in rapid mixed basin with coagulant. Powdered activated carbon porosity reduction due to effect of coagulant can be the reason for this issue.Also according to different paths, the point of intake is more suitable for powdered activated carbon addition.

  4. Enhanced energy conversion efficiency from high strength synthetic organic wastewater by sequential dark fermentative hydrogen production and algal lipid accumulation.

    Science.gov (United States)

    Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Xing, Defeng; Ren, Nan-Qi

    2014-04-01

    A two-stage process of sequential dark fermentative hydrogen production and microalgal cultivation was applied to enhance the energy conversion efficiency from high strength synthetic organic wastewater. Ethanol fermentation bacterium Ethanoligenens harbinense B49 was used as hydrogen producer, and the energy conversion efficiency and chemical oxygen demand (COD) removal efficiency reached 18.6% and 28.3% in dark fermentation. Acetate was the main soluble product in dark fermentative effluent, which was further utilized by microalga Scenedesmus sp. R-16. The final algal biomass concentration reached 1.98gL(-1), and the algal biomass was rich in lipid (40.9%) and low in protein (23.3%) and carbohydrate (11.9%). Compared with single dark fermentation stage, the energy conversion efficiency and COD removal efficiency of two-stage system remarkably increased 101% and 131%, respectively. This research provides a new approach for efficient energy production and wastewater treatment using a two-stage process combining dark fermentation and algal cultivation. PMID:24582427

  5. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans

    OpenAIRE

    Henstra, Anne M.; Stams, Alfons J. M.

    2011-01-01

    Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently lo...

  6. Efficient energy conversion in the pulp and paper industry: application to a sulfite wood pulping process

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, F.

    2007-07-01

    This report measures the actions performed in 2006 and the actions planned for 2007 within the framework of the project Efficient Energy Conversion in the Pulp and Paper Industry. In addition to the data reconciliation models of the steam and condensate networks and of the process of Borregaard Schweiz AG, process models have been developed with the goal of defining the heat requirements of the process. The combination of utility system data reconciliation with the process models allows to considerably reduce the need for detailed process modelling and for on-site data collection and measurement. A systematic definition of the hot and cold streams in the process has been developed in order to compute the minimum energy requirement of the process. The process requirements have been defined using the dual representation concept where the energy requirement of the process unit operations are systematically analysed from their thermodynamic requirement and the way they are satisfied by the technology that implements the operation. Corresponding to the same energy requirement but realised with different temperature allows on one hand to define the exergy efficiency of the heat transfer system in each of the process unit operations and to identify possible energy savings by heat exchange in the system. The analysis has been completed by the definition of the possible energy recovery from waste streams. The minimum energy requirement of the process using the different requirement representation has been realised and the analysis of the energy savings opportunities is now under preparation. This new step will first concern the definition of the utility system integration and the systematic analysis of the energy savings opportunities followed by the techno-economic evaluation of the most profitable energy savings options in the process. The national and international collaborations constitute also an important part of this project. The project is done in close

  7. Power conversion and quality of the Santa Clara 2 MW direct carbonate fuel cell demonstration plant

    Energy Technology Data Exchange (ETDEWEB)

    Skok, A.J. [Fuel Cell Engineering Corp., Danbury, CT (United States); Abueg, R.Z. [Basic Measuring Instruments, Santa Clara, CA (United States); Schwartz, P. [Fluor Daniel, Inc., Irvine, CA (United States)] [and others

    1996-12-31

    The Santa Clara Demonstration Project (SCDP) is the first application of a commercial-scale carbonate fuel cell power plant on a US electric utility system. It is also the largest fuel cell power plant ever operated in the United States. The 2MW plant, located in Santa Clara, California, utilizes carbonate fuel cell technology developed by Energy Research Corporation (ERC) of Danbury, Connecticut. The ultimate goal of a fuel cell power plant is to deliver usable power into an electrical distribution system. The power conversion sub-system does this for the Santa Clara Demonstration Plant. A description of this sub-system and its capabilities follows. The sub-system has demonstrated the capability to deliver real power, reactive power and to absorb reactive power on a utility grid. The sub-system can be operated in the same manner as a conventional rotating generator except with enhanced capabilities for reactive power. Measurements demonstrated the power quality from the plant in various operating modes was high quality utility grade power.

  8. Design of hybrid nanoheterostructure systems for enhanced quantum and solar conversion efficiencies in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kılıç, Bayram, E-mail: bkilic@yalova.edu.tr, E-mail: kbayramkilic@gmail.com [Department of Energy Systems Engineering, Faculty of Engineering, Yalova University, 77100 Yalova (Turkey); Telli, Hakan; Başaran, Ali; Pirge, Gursev [Turkish Air Force Academy, Institute of Aeronautics and Space Technologies, Istanbul (Turkey); Tüzemen, Sebahattin [Department of Physics, Faculty of Science, Ataturk University, Erzurum (Turkey)

    2015-04-07

    Dye sensitized solar cells (DSSCs) with an innovative design involving controlled-morphology vertically aligned (VA) ZnO nanowires within mesoporous TiO{sub 2} structures with ultrahigh surface area for implementation as photoanodes are herein reported. Although TiO{sub 2} nanostructures exhibit excellent power conversion efficiency, the electron transport rate is low owing to low electron mobility. To overcome this, ZnO nanowires with high electron mobility have been investigated as potential candidates for photoanodes. However, the power conversion efficiency of ZnO nanowires is still lower than that of TiO{sub 2} owing to their low internal surface area. Consequently, in this work, vertical growth of ZnO nanowires within mesoporous TiO{sub 2} structures is carried out to increase their solar power conversion efficiency. The photovoltaic performance of solar cells using ZnO nanowires, mesoporous TiO{sub 2}, and TiO{sub 2}/ZnO hybrid structures are compared. The VA TiO{sub 2}/ZnO hybrid structures are found to provide direct electron transfer compared with the tortuous pathway of zero-dimensional nanostructures, resulting in an increased conversion efficiency. It is demonstrated that the light scattering of the photoanode film is increased and electron recombination is decreased when an appropriate amount of mesoporous TiO{sub 2} is used as a substrate for ZnO nanowires. The DSSC fabricated with the TiO{sub 2}/ZnO hybrid photoanode prepared with 15.8 wt. % TiO{sub 2} showed the highest conversion efficiency of 7.30%, approximately 5%, 18%, and 40% higher than that of DSSCs fabricated with 3.99 wt. % TiO{sub 2}, pure TiO{sub 2}, and pure ZnO photoanodes, respectively.

  9. Design of hybrid nanoheterostructure systems for enhanced quantum and solar conversion efficiencies in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Dye sensitized solar cells (DSSCs) with an innovative design involving controlled-morphology vertically aligned (VA) ZnO nanowires within mesoporous TiO2 structures with ultrahigh surface area for implementation as photoanodes are herein reported. Although TiO2 nanostructures exhibit excellent power conversion efficiency, the electron transport rate is low owing to low electron mobility. To overcome this, ZnO nanowires with high electron mobility have been investigated as potential candidates for photoanodes. However, the power conversion efficiency of ZnO nanowires is still lower than that of TiO2 owing to their low internal surface area. Consequently, in this work, vertical growth of ZnO nanowires within mesoporous TiO2 structures is carried out to increase their solar power conversion efficiency. The photovoltaic performance of solar cells using ZnO nanowires, mesoporous TiO2, and TiO2/ZnO hybrid structures are compared. The VA TiO2/ZnO hybrid structures are found to provide direct electron transfer compared with the tortuous pathway of zero-dimensional nanostructures, resulting in an increased conversion efficiency. It is demonstrated that the light scattering of the photoanode film is increased and electron recombination is decreased when an appropriate amount of mesoporous TiO2 is used as a substrate for ZnO nanowires. The DSSC fabricated with the TiO2/ZnO hybrid photoanode prepared with 15.8 wt. % TiO2 showed the highest conversion efficiency of 7.30%, approximately 5%, 18%, and 40% higher than that of DSSCs fabricated with 3.99 wt. % TiO2, pure TiO2, and pure ZnO photoanodes, respectively

  10. Design of hybrid nanoheterostructure systems for enhanced quantum and solar conversion efficiencies in dye-sensitized solar cells

    Science.gov (United States)

    Kılıç, Bayram; Telli, Hakan; Tüzemen, Sebahattin; Başaran, Ali; Pirge, Gursev

    2015-04-01

    Dye sensitized solar cells (DSSCs) with an innovative design involving controlled-morphology vertically aligned (VA) ZnO nanowires within mesoporous TiO2 structures with ultrahigh surface area for implementation as photoanodes are herein reported. Although TiO2 nanostructures exhibit excellent power conversion efficiency, the electron transport rate is low owing to low electron mobility. To overcome this, ZnO nanowires with high electron mobility have been investigated as potential candidates for photoanodes. However, the power conversion efficiency of ZnO nanowires is still lower than that of TiO2 owing to their low internal surface area. Consequently, in this work, vertical growth of ZnO nanowires within mesoporous TiO2 structures is carried out to increase their solar power conversion efficiency. The photovoltaic performance of solar cells using ZnO nanowires, mesoporous TiO2, and TiO2/ZnO hybrid structures are compared. The VA TiO2/ZnO hybrid structures are found to provide direct electron transfer compared with the tortuous pathway of zero-dimensional nanostructures, resulting in an increased conversion efficiency. It is demonstrated that the light scattering of the photoanode film is increased and electron recombination is decreased when an appropriate amount of mesoporous TiO2 is used as a substrate for ZnO nanowires. The DSSC fabricated with the TiO2/ZnO hybrid photoanode prepared with 15.8 wt. % TiO2 showed the highest conversion efficiency of 7.30%, approximately 5%, 18%, and 40% higher than that of DSSCs fabricated with 3.99 wt. % TiO2, pure TiO2, and pure ZnO photoanodes, respectively.

  11. High efficiency carbonate fuel cell/turbine hybrid power cycles

    Energy Technology Data Exchange (ETDEWEB)

    Steinfeld, G. [Energy Research Corp., Danbury, CT (United States)

    1995-10-19

    Carbonate fuel cells developed by Energy Research Corporation, in commercial 2.85 MW size, have an efficiency of 57.9 percent. Studies of higher efficiency hybrid power cycles were conducted in cooperation with METC to identify an economically competitive system with an efficiency in excess of 65 percent. A hybrid power cycle was identified that includes a direct carbonate fuel cell, a gas turbine and a steam cycle, which generates power at a LHV efficiency in excess of 70 percent. This new system is called a Tandem Technology Cycle (TTC). In a TTC operating on natural gas fuel, 95 percent of the fuel is mixed with recycled fuel cell anode exhaust, providing water for the reforming of the fuel, and flows to a direct carbonate fuel cell system which generates 72 percent of the power. The portion of the fuel cell anode exhaust which is not recycled, is burned and heat is transferred to the compressed air from a gas turbine, raising its temperature to 1800{degrees}F. The stream is then heated to 2000{degrees}F in the gas turbine burner and expands through the turbine generating 13 percent of the power. Half the exhaust from the gas turbine flows to the anode exhaust burner, and the remainder flows to the fuel cell cathodes providing the O{sub 2} and CO{sub 2} needed in the electrochemical reaction. Exhaust from the fuel cells flows to a steam system which includes a heat recovery steam generator and stages steam turbine which generates 15 percent of the TTC system power. Studies of the TTC for 200-MW and 20-MW size plants quantified performance, emissions and cost-of-electricity, and compared the characteristics of the TTC to gas turbine combined cycles. A 200-MW TTC plant has an efficiency of 72.6 percent, and is relatively insensitive to ambient temperature, but requires a heat exchanger capable of 2000{degrees}F. The estimated cost of electricity is 45.8 mills/kWhr which is not competitive with a combined cycle in installations where fuel cost is under $5.8/MMBtu.

  12. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 5: Combined gas-steam turbine cycles. [energy conversion efficiency in electric power plants

    Science.gov (United States)

    Amos, D. J.; Foster-Pegg, R. W.; Lee, R. M.

    1976-01-01

    The energy conversion efficiency of gas-steam turbine cycles was investigated for selected combined cycle power plants. Results indicate that it is possible for combined cycle gas-steam turbine power plants to have efficiencies several point higher than conventional steam plants. Induction of low pressure steam into the steam turbine is shown to improve the plant efficiency. Post firing of the boiler of a high temperature combined cycle plant is found to increase net power but to worsen efficiency. A gas turbine pressure ratio of 12 to 1 was found to be close to optimum at all gas turbine inlet temperatures that were studied. The coal using combined cycle plant with an integrated low-Btu gasifier was calculated to have a plant efficiency of 43.6%, a capitalization of $497/kW, and a cost of electricity of 6.75 mills/MJ (24.3 mills/kwh). This combined cycle plant should be considered for base load power generation.

  13. Resource limits and conversion efficiency with implications for climate change and California's energy supply

    Science.gov (United States)

    Croft, Gregory Donald

    on aggregated reserve numbers. Electric power generation consumes 92 percent of U.S. coal production. Natural gas competes with coal as a baseload power generation fuel with similar or slightly better generation efficiency. Fischer-Tropsch synthesis, described in Chapter 2, creates transportation fuel from coal with an efficiency of less than 45 percent. Claims of higher efficiencies are based on waste heat recovery, since this is a highly exothermic process. The yield of liquid fuel as a proportion of the energy content of the coal input is always less than 45 percent. Compressed natural gas can be used for vehicle fuel with efficiency greater than 98 percent. If we view Fischer-Tropsch synthesis as a form of arbitrage between markets for electricity and transportation fuel, coal cannot simultaneously compete with natural gas for both transportation fuel and electric power. This is because Fischer-Tropsch synthesis is a way to turn power generation fuel into transportation fuel with low efficiency, while natural gas can be converted to transportation fuel with much greater efficiency. For this reason, Fischer-Tropsch synthesis will be an uneconomic source of transportation fuel as long as natural gas is economic for power generation. This conclusion holds even without the very high capital cost of coal-to-liquids plants. The Intergovernmental Panel on Climate Change (IPCC) has generated forty carbon production and emissions scenarios, see the IPCC Special Report on Emissions Scenarios (2000). Chapter 4 develops a base-case scenario for global coal production based on the physical multi-cycle Hubbert analysis of historical production data. Areas with large resources but little production history, such as Alaska or Eastern Siberia, can be treated as sensitivities on top of this base case. The value of our approach is that it provides a reality check on the magnitude of carbon emissions in a business-as-usual (BAU) scenario. The resulting base case is significantly

  14. Color-conversion efficiency enhancement of quantum dots via selective area nano-rods light-emitting diodes.

    Science.gov (United States)

    Liu, Che-Yu; Chen, Tzu-Pei; Kao, Tsung Sheng; Huang, Jhih-Kai; Kuo, Hao-Chung; Chen, Yang-Fang; Chang, Chun-Yen

    2016-08-22

    A large enhancement of color-conversion efficiency of colloidal quantum dots in light-emitting diodes (LEDs) with novel structures of nanorods embedded in microholes has been demonstrated. Via the integration of nano-imprint and photolithography technologies, nanorods structures can be fabricated at specific locations, generating functional nanostructured LEDs for high-efficiency performance. With the novel structured LED, the color-conversion efficiency of the existing quantum dots can be enhanced by up to 32.4%. The underlying mechanisms can be attributed to the enhanced light extraction and non-radiative energy transfer, characterized by conducting a series of electroluminescence and time-resolved photoluminescence measurements. This hybrid nanostructured device therefore exhibits a great potential for the application of multi-color lighting sources. PMID:27557273

  15. Efficiency enhancement in dye-sensitized solar cells with down conversion material ZnO: Eu3+, Dy3+

    Science.gov (United States)

    Yao, Nannan; Huang, Jinzhao; Fu, Ke; Liu, Shiyou; E, Dong; Wang, Yanhao; Xu, Xijin; Zhu, Min; Cao, Bingqiang

    2014-12-01

    The down conversion (DC) material ZnO: Eu3+, Dy3+ are synthesized by precipitation method and used to prepare the photo anode of dye-sensitized solar cells (DSSCs). The effects of down conversion material on the photoelectric performance of the DSSC were characterized by the X-ray diffraction (XRD), photoluminescence (PL), scanning electron microscope (SEM), current-voltage (I-V) curve, incident-photon-to-current conversion efficiency (IPCE) and UV-vis-NIR absorption spectroscopy. In this paper, Eu3+, Dy3+ codoped ZnO excited by from UV to blue light converts blue to red light emission, corresponding to the absorption region of the dye (N719). At the concentration 1.75% of ZnO: Eu3+, Dy3+ (weight ratio of DC to TiO2), the short-circuit current density and conversion efficiency of the DSSCs reached to the optimal values: 8.92 mA cm-2 and 4.48%, about 212% and 245% higher than with pure TiO2 and about 91.4% and 105% higher than with TiO2/graphene (G) structure, respectively. The research result reveals that the application of DC material can improve the efficiency of DSSCs.

  16. Integrated Three-Dimensional Carbon Paper/Carbon Tubes/Cobalt-Sulfide Sheets as an Efficient Electrode for Overall Water Splitting.

    Science.gov (United States)

    Wang, Jun; Zhong, Hai-xia; Wang, Zhong-li; Meng, Fan-lu; Zhang, Xin-bo

    2016-02-23

    The development of an efficient catalytic electrode toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for overall water splitting associated with the conversion and storage of clean and renewable energy. In this study, carbon paper/carbon tubes/cobalt-sulfide is introduced as an integrated three-dimensional (3D) array electrode for cost-effective and energy-efficient HER and OER in alkaline medium. Impressively, this electrode displays superior performance compared to non-noble metal catalysts reported previously, benefiting from the unique 3D array architecture with increased exposure and accessibility of active sites, improved vectorial electron transport capability, and enhanced release of gaseous products. Such an integrated and versatile electrode makes the overall water splitting proceed in a more direct and smooth manner, reducing the production cost of practical technological devices. PMID:26783885

  17. Conversion of CO2 into Commercial Materials Using Carbon Feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Jian-Ping [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Peters, Jonathan [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Lail, Marty [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Mobley, Paul [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Turk, Brian [Research Triangle Institute (RTI), Research Triangle Park, NC (United States)

    2014-05-31

    In this project, our research focused on developing reaction chemistry that would support using carbon as a reductant for CO2 utilization that would permit CO2 consumption on a scale that would match or exceed anthropomorphic CO2 generation for energy production from fossil fuels. Armed with the knowledge that reactions attempting to produce compounds with an energy content greater than CO2 would be thermodynamically challenged and/or require significant amounts of energy, we developed a potential process that utilized a solid carbon source and recycled the carbon to effectively provide infinite time for the carbon to react. During testing of different carbon sources, we found a wide range of reaction rates. Biomass-derived samples had the most reactivity and coals and petcoke had the lowest. Because we had anticipated this challenge, we recognized that a catalyst would be necessary to improve reaction rates and conversion. From the data analysis of carbon samples, we recognized that alkali metals improved the reaction rate. Through parametric testing of catalyst formulations we were able to increase the reaction rate with petcoke by a factor of >70. Our efforts to identify the reaction mechanism to assist in improving the catalyst formulation demonstrated that the catalyst was catalyzing the extraction of oxygen from CO2 and using this extracted oxygen to oxidize carbon. This was a significant discovery in that if we could modify the catalyst formulation to permit controlled the oxidation, we would have a very power selective oxidation process. With selective oxidation, CO2 utilization could be effective used as one of the process steps in making many of the large volume commodity chemicals that support our modern lifestyles. The key challenges for incorporating these functionalities into the catalyst formulation were to make the oxidation selective and lower the temperature required for catalytic

  18. Pt/Mesoporous Carbon Counter Electrode with a Low Pt Loading for High-Efficient Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Guiqiang Wang

    2010-01-01

    Full Text Available Pt/Mesoporous carbon counter electrodes with a low Pt loading for dye-sensitized solar cells were fabricated by coating Pt/mesoporous carbon on fluorine-doped tin oxide glass. Pt/mesoporous carbon samples were prepared by reducing H2PtCl6 with NaBH4 in mesoporous carbon and characterized by N2 adsorption analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Pt particles deposited on mesoporous carbon support were found to be in uniform shape and narrow range of particle size. Low-Pt-loading Pt/mesoporous carbon counter electrode showed a high electrocatalytic activity for triiodide reduction. Electrochemical impedance spectroscopy measurement displayed a low charge-transfer resistance of 1.2 Ωcm2 for 1-Pt/mesoporous carbon counter electrode. Dye-sensitized solar cells based on the 1-Pt/mesoporous carbon counter electrode achieved an overall conversion efficiency of 6.62% under one sun illumination, which is higher than that of the cell with the conventional Pt counter electrode.

  19. High-Efficiency, Nanowire Based Thermoelectric Devices for Radioisotope Power Conversion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal responds to topic S3.03 of the 2010 NASA SBIR solicitation, for Power Generation and Conversion. Thermoelectric devices offer a simple...

  20. External magnetic field effect on bifacial silicon solar cell''s electric power and conversion efficiencyExternal magnetic field effect on bifacial silicon solar cell''s electric power and conversion efficiency

    OpenAIRE

    ZERBO, ISSA; ZOUNGRANA, MARTIAL; SOURABIE, IDRISSA; Ouedraogo, Adama; ZOUMA, BERNARD; BATHIEBO, DIEUDONNE JOSEPH

    2015-01-01

    This article presents a modelling study of external magnetic field effect on a bifacial silicon solar cell's electric power and conversion efficiency. After the resolution of the magnetotransport equation and continuity equation of excess minority carriers, we calculate the photocurrent density and the photovoltage and then we deduce the solar cell's electric power before discussing the influence of the magnetic field on those electrical parameters. Using the electric power curves...

  1. Carbon materials for an efficient use of energy by electrochemical devices

    OpenAIRE

    Lázaro, M. J.; I. Suelves; R. Moliner

    2012-01-01

    [EN] The efficient use of energy, in particular electricity, requires devices allowing its storage and subsequent conversion into work with a high yield. Electrochemical devices are very effective since the absence of mechanical moving parts reduces irreversibility and provides high efficient conversions. The efficiency of the device depends on the performance of the electrodes, which depends on the properties of the materials that compose them. Because most of the ...

  2. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 12: Fuel cells. [energy conversion efficiency of, for use in electric power plants

    Science.gov (United States)

    Warde, C. J.; Ruka, R. J.; Isenberg, A. O.

    1976-01-01

    A parametric assessment of four fuel cell power systems -- based on phosphoric acid, potassium hydroxide, molten carbonate, and stabilized zirconia -- has shown that the most important parameters for electricity-cost reduction and/or efficiency improvement standpoints are fuel cell useful life and power density, use of a waste-heat recovery system, and fuel type. Typical capital costs, overall energy efficiencies (based on the heating value of the coal used to produce the power plant fuel), and electricity costs are: phosphoric acid $350-450/kWe, 24-29%, and 11.7 to 13.9 mills/MJ (42 to 50 mills/kWh); alkaline $450-700/kWe, 26-31%, and 12.8 to 16.9 mills/MJ (46 to 61 mills/kWh); molten carbonate $480-650/kWe, 32-46%, and 10.6 to 19.4 mills/MJ (38 to 70 mills/kWh), stabilized zirconia $420-950/kWe, 26-53%, and 9.7 to 16.9 mills/MJ (35 to 61 mills/kWh). Three types of fuel cell power plants -- solid electrolytic with steam bottoming, molten carbonate with steam bottoming, and solid electrolyte with an integrated coal gasifier -- are recommended for further study.

  3. A field study on the conversion ratio of phytoplankton biomass carbon to chlorophyll-a in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    L(U) Shuguo; Wang Xuchen; Han Boping

    2009-01-01

    A one-year field study was conducted to determine the conversion ratio of phytoplankton biomass carbon (Phyto-C) to chlorophyll-a (Chl-a) in Jiaozhou Bay, China. We measured suspended particulate organic carbon (POC) and phytoplankton Chl-a samples collected in surface water monthly from March 2005 to February 2006. The temporal and spatial variations of Chl-a and POC concentrations were observed in the bay. Based on the field measurements, a linear regression model II was used to generate the conversion ratio of Phyto-C to Chl-a. In most cases, a good linear correlation was found between the observed POC and Chl-a concentrations, and the calculated conversion ratios ranged from 26 to 250 with a mean value of 56 ìg ìg~(-1). The conversion ratio in the fall was higher than that in the winter and spring months, and had the lowest values in the summer. The ratios also exhibited spatial variations, generally with low values in the near shore regions and relatively high values in offshore waters. Our study suggests that temperature was likely to be the main factor influencing the observed seasonal variations of conversion ratios while nutrient supply and light penetration played important roles in controlling the spatial variations.

  4. Optimal Materials and Deposition Technique Lead to Cost-Effective Solar Cell with Best-Ever Conversion Efficiency (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2012-07-01

    This fact sheet describes how the SJ3 solar cell was invented, explains how the technology works, and why it won an R&D 100 Award. Based on NREL and Solar Junction technology, the commercial SJ3 concentrator solar cell - with 43.5% conversion efficiency at 418 suns - uses a lattice-matched multijunction architecture that has near-term potential for cells with {approx}50% efficiency. Multijunction solar cells have higher conversion efficiencies than any other type of solar cell. But developers of utility-scale and space applications crave even better efficiencies at lower costs to be both cost-effective and able to meet the demand for power. The SJ3 multijunction cell, developed by Solar Junction with assistance from foundational technological advances by the National Renewable Energy Laboratory, has the highest efficiency to date - almost 2% absolute more than the current industry standard multijunction cell-yet at a comparable cost. So what did it take to create this cell having 43.5% efficiency at 418-sun concentration? A combination of materials with carefully designed properties, a manufacturing technique allowing precise control, and an optimized device design.

  5. High energy conversion efficiency in laser-proton acceleration by controlling laser-energy deposition onto thin foil targets

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, C. M. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Robinson, A. P. L.; Markey, K.; Scott, R. H. H.; Lancaster, K. L.; Musgrave, I. O.; Spindloe, C.; Winstone, T.; Wyatt, D.; Neely, D. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom); Gray, R. J.; McKenna, P. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Rosinski, M.; Badziak, J.; Wolowski, J. [Institute of Plasma Physics and Laser Microfusion, 00-908 Warsaw (Poland); Deppert, O. [Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt (Germany); Batani, D. [Dipartimento di Fisica G. Occhialini, Universita di Milano Bicocca, 20126 Milan (Italy); Davies, J. R. [Laboratory for Laser Energetics, Fusion Science Center for Extreme States of Matter, University of Rochester, Rochester, New York 14623 (United States); Hassan, S. M.; Tatarakis, M. [Department of Electronics Engineering, Centre for Plasma Physics and Lasers, 73133 Chania, 74100 Rethymno, Crete (Greece); and others

    2014-02-24

    An all-optical approach to laser-proton acceleration enhancement is investigated using the simplest of target designs to demonstrate application-relevant levels of energy conversion efficiency between laser and protons. Controlled deposition of laser energy, in the form of a double-pulse temporal envelope, is investigated in combination with thin foil targets in which recirculation of laser-accelerated electrons can lead to optimal conditions for coupling laser drive energy into the proton beam. This approach is shown to deliver a substantial enhancement in the coupling of laser energy to 5–30 MeV protons, compared to single pulse irradiation, reaching a record high 15% conversion efficiency with a temporal separation of 1 ps between the two pulses and a 5 μm-thick Au foil. A 1D simulation code is used to support and explain the origin of the observation of an optimum pulse separation of ∼1 ps.

  6. Optimal enhancement in conversion efficiency of crystalline Si solar cells using inverse opal photonic crystals as back reflectors

    International Nuclear Information System (INIS)

    The effect of using inverse opal photonic crystals as back reflectors on the power conversion efficiency of c-Si solar cells is investigated. The reflection spectra of inverse opal photonic crystals with different diameters of air spheres are simulated using the finite difference time domain (FDTD) method. The reflection peaks are correlated with photonic band gaps present in the photonic band gap diagram. Significant improvement in the optical absorption of the crystalline silicon layer is recorded when inverse opal photonic crystals are considered. Physical mechanisms which may contribute to the enhancement of the light absorption are underlined. With higher short-circuit current enhancement possible, and with no corresponding degradation in open-circuit voltage Voc or the fill factor, the power conversion efficiency is increased significantly when inverse opal photonic crystals are used as back reflectors with optimized diameter of air spheres. (paper)

  7. X-ray conversion efficiency as a function of atomic number for 0.26-micron-laser - Irradiated targets

    Science.gov (United States)

    Alaterre, P.; Pepin, H.; Fabbro, R.; Faral, B.

    1986-11-01

    Soft-X-ray low-resolution experimental spectra are obtained for a large set of targets irradiated at 2 x 10 to the 14th W/sq cm by 0.26-micron radiation. X-ray conversion efficiencies in various spectral ranges are studied as a function of atomic number. To calculate the emissivity, a simple, multiple-Z atomic-physics model is developed based on a screened-hydrogenic description for the atomic structure and on a non-LTE modified Saha approach to plasma-ionization properties. Experimental soft-X-ray spectra are replicated by using a discrete summation of emissivities over a few temperatures with appropriate weighting factors determined from the experiment or through a separate hydrodynamic-code simulation. The modulations in the Z dependence of the X-ray conversion efficiency in various spectral ranges are well described and interpreted.

  8. Patterning ITO by Template-Assisted Colloidal-Lithography for Enhancing Power Conversion Efficiency in Organic Photovoltaic.

    Science.gov (United States)

    Lee, Jin-Su; Yu, Jung-Hun; Hwang, Ki-Hwan; Nam, Sang-Hun; Boo, Jin-Hyo; Yun, Sang H

    2016-05-01

    Highly structured interfaces are very desirable in organic photovoltaic solar cells (OPVs), in order to enhance power conversion efficiency (PCE) by decreasing of the transport path for excited charge carriers in the absorber and increasing the optical path length for photon absorption. Many complicated, high-cost lithographic methods have been attempted to modify the surface of the absorber or substrate. However, solution-based colloidal-lithography processes are scalable and cost-effective, but generally result in non-uniform structured surfaces. In this report, we demonstrated an optimized silica-templated colloidal lithographical approach to create a well-defined and controlled transparent ITO layer for enhancing power conversion efficiency (PCE). Additionally, morphological effects of the patterned ITO on optical properties and PCE were analyzed in detail. PMID:27483864

  9. Efficient continuous-wave nonlinear frequency conversion in high-Q Gallium Nitride photonic crystal cavities on Silicon

    CERN Document Server

    Mohamed, Mohamed Sabry; Carlin, Jean-François; Minkov, Momchil; Gerace, Dario; Savona, Vincenzo; Grandjean, Nicolas; Galli, Matteo; Houdré, Romuald

    2016-01-01

    We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG) and third harmonic generation (THG) in suspended gallium nitride slab photonic crystal (PhC) cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4$\\times10^{4}$, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving normalized conversion efficiency of 2.4$\\times10^{-3}$ $W^{-1}$, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  10. Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

    Institute of Scientific and Technical Information of China (English)

    Aiying Yang; Yunan Sun

    2008-01-01

    @@ 40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.

  11. Fabrication of Natural Sensitizer Extracted from Mixture of Purple Cabbage, Roselle, Wormwood and Seaweed with High Conversion Efficiency for DSSC.

    Science.gov (United States)

    Chang, Ho; Lai, Xuan-Rong

    2016-02-01

    This study aims to deal with the influence of different solvent in extraction of natural sensitizer and different thickness of photoelectrode thin film on the photoelectric conversion efficiency and the electron transport properties for the prepared dye-sensitized solar cells (DSSC). The natural dyes of anthocyanin and chlorophyll dyes are extracted from mixture of purple cabbage and roselle and mixture of wormwood and seaweed, respectively. The experimental results show the cocktail dye extracted with ethanol and rotating speed of spin coating at 1000 rpm can achieve the greatest photoelectric conversion efficiency up to 1.85%. Electrochemical impedance result shows that the effective diffusion coefficient for the prepared DSSC with the thickness of photoelectrode thin film at 21 microm are 5.23 x 10(-4) cm2/s. PMID:27433731

  12. Dehydrogenation of Formic Acid at Room Temperature: Boosting Palladium Nanoparticle Efficiency by Coupling with Pyridinic-Nitrogen-Doped Carbon.

    Science.gov (United States)

    Bi, Qing-Yuan; Lin, Jian-Dong; Liu, Yong-Mei; He, He-Yong; Huang, Fu-Qiang; Cao, Yong

    2016-09-19

    The use of formic acid (FA) to produce molecular H2 is a promising means of efficient energy storage in a fuel-cell-based hydrogen economy. To date, there has been a lack of heterogeneous catalyst systems that are sufficiently active, selective, and stable for clean H2 production by FA decomposition at room temperature. For the first time, we report that flexible pyridinic-N-doped carbon hybrids as support materials can significantly boost the efficiency of palladium nanoparticle for H2 generation; this is due to prominent surface electronic modulation. Under mild conditions, the optimized engineered Pd/CN0.25 catalyst exhibited high performance in both FA dehydrogenation (achieving almost full conversion, and a turnover frequency of 5530 h(-1) at 25 °C) and the reversible process of CO2 hydrogenation into FA. This system can lead to a full carbon-neutral energy cycle. PMID:27552650

  13. Conducting polymer/carbon nanocoil composite electrodes for efficient supercapacitors

    KAUST Repository

    Baby, Rakhi Raghavan

    2012-01-01

    Herein, we report for the first time, conducting polymer (polyaniline (PANI) and polypyrrole (PPY)) coated carbon nanocoils (CNCs) as efficient binder-free electrode materials for supercapacitors. CNCs act as a perfect backbone for the uniform distribution of the conducting polymers in the composites. In two electrode configuration, the samples exhibited high specific capacitance with the values reaching up to 360 and 202 F g -1 for PANI/CNCs and PPY/CNCs respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be comparable to one of the best reported values for polymer coated multi-walled carbon nanotubes. In addition, the fabricated PANI/CNC based supercapacitors exhibited a high value of 44.61 Wh kg -1 for maximum storage energy per unit mass. Although the devices exhibit an initial capacitance loss due to the instability of the polymer, the specific capacitance stabilizes at a fixed value after 500 charge-discharge cycles. © 2012 The Royal Society of Chemistry.

  14. Extremely Efficient Multiple Electron-hole Pair Generation in Carbon Nanotube Photodiodes

    Science.gov (United States)

    Gabor, Nathaniel

    2010-03-01

    The efficient generation of multiple electron-hole (e-h) pairs from a single photon could improve the efficiency of photovoltaic solar cells beyond standard thermodynamic limits [1] and has been the focus of much recent work in semiconductor nanomaterials [2,3]. In single walled carbon nanotubes (SWNTs), the small Fermi velocity and low dielectric constant suggests that electron-electron interactions are very strong and that high-energy carriers should efficiently generate e-h pairs. Here, I will discuss observations of highly efficient generation of e-h pairs due to impact excitation in SWNT p-n junction photodiodes [4]. To investigate optoelectronic transport properties of individual SWNT photodiodes, we focus a laser beam over the device while monitoring the electronic characteristics. Optical excitation into the second electronic subband E22 ˜ 2 EGAP leads to striking photocurrent steps in the device I-VSD characteristics that occur at voltage intervals of the band gap energy EGAP/ e. Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple e-h pairs from a single hot E22 carrier. We conclude that in the SWNT photodiode, a single photon with energy greater than 2EGAP is converted into multiple e-h pairs, leading to enhanced photocurrent and increased photo-conversion efficiency. [1] W. Shockley, and H. J. Queisser, Journal of Applied Physics 32, 510 (1961). [2] R. D. Schaller, and V. I. Klimov, Physical Review Letters 92 (18), 186601 (2004). [3] R. J. Ellingson, et al, Nano Letters, 5 (5), 865-871 (2005). [4] Nathaniel M. Gabor, Zhaohui Zhong, Ken Bosnick, Jiwoong Park, and Paul McEuen, Science, 325, 1367 (2009).

  15. Annealing group III-V compound doped silicon-germanium alloy for improved thermo-electric conversion efficiency

    Science.gov (United States)

    Vandersande, Jan W. (Inventor); Wood, Charles (Inventor); Draper, Susan L. (Inventor)

    1989-01-01

    The thermoelectric conversion efficiency of a GaP doped SiGe alloy is improved about 30 percent by annealing the alloy at a temperature above the melting point of the alloy, preferably stepwise from 1200 C to 1275 C in air to form large grains having a size over 50 microns and to form a GeGaP rich phase and a silicon rich phase containing SiP and SiO2 particles.

  16. Increase in the DSSC efficiency when using metal-coated carbon nanowall counter electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangjoon; Choi, Wonseok [Hanbat National University, Daejeon (Korea, Republic of); Lim, Donggun [Korea National University of Transportation, Chungju (Korea, Republic of); Choi, Eunchang; Hong, Byungyou [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-08-15

    This research was conducted to improve the efficiency of dye-sensitized solar cells (DSSCs) using metal-layer-coated carbon nanowalls (CNWs) as counter electrodes. The CNWs were synthesized on a fluorine-doped tin-oxide (FTO) glass substrate in a microwave plasma-enhanced chemical vapor deposition (PECVD) system using methane (CH{sub 4}), and the CNWS were sputter-coated with metal films several times by using an RF magnetron sputtering system and four-inch metal targets (Cu, W and Ni, separately). Then, the metal-layer-coated CNWs were used as counter electrodes for manufacturing the DSCCs. The vertical and the surface conditions of the metal-coated CNWs used as the DSCC electrodes were characterized by their electrical variations through field-emission scanning electron microscopy (FE-SEM) and Hall measurements. Their optical characteristics were analyzed using UV-Vis equipment, and the energy conversion efficiencies of the DSSCs manufactured using the metal-layer-coated CNWs as the counter electrodes were measured. The results confirmed that the efficiency improved when the W-coated CNW was used as the counter electrode.

  17. Design of electrolyzer for carbon dioxide conversion to fuels and chemicals

    Science.gov (United States)

    Rosen, Jonathan S.

    The stabilization of global atmospheric CO2 levels requires a transition towards a renewable energy based economy as well as methods for handling current CO2 output from fossil fuels. Challenges with renewable energy intermittency have thus far limited the use of these alternative energy sources to only a fraction of the current energy portfolio. To enable more widespread use of renewable energy systems, methods of large scale energy storage must be developed to store excess renewable energy when demand is low and allow for combined use of energy storage and renewable systems when demand is high. To date, no one technique has demonstrated energy storage methods on the gigawatt scale needed for integration with renewable sources; therefore the development of suitable energy storage technologies, such as CO2 electrolysis to fuels is needed. In this work, research efforts have focused on two major thrusts related to electrochemical methods of CO 2 conversion to fuels. The first thrust focuses on the synthesis and design of highly efficient anode and cathode catalysts with emphasis on understanding structure-property relationships. A second thrust focuses on the design of novel electrochemical devices for CO2 conversion and integration of synthesized materials into flow cell systems. On the anode side, the synthesis of highly active catalysts using abundant transition metals is crucial to reducing capital costs and enabling widespread use of electrochemical CO2 conversion devices. Highly active mesoporous Co3O4 and metal-substituted Co3O4 water oxidation catalysts were designed to investigate the role of the spinel structure on water oxidation activity. Further analysis of metal substituted samples reveal the importance of the octahedral sites in the spinel structure, which was later used to design an Mg-Co3O4 sample with improved water oxidation activity. The design of efficient cathode materials which can selectivity reduce CO2 to fuels and chemicals is critical to

  18. Bacterial growth efficiency in a tropical estuary: Seasonal variability subsidized by allochthonous carbon

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.S.P.; Nair, S.; Chandramohan, D.

    Bacterial growth efficiency (BGE) is a key factor in understanding bacterial influence on carbon flow in aquatic ecosystems. Intra-annual variability in BGE, and bacteria-mediated carbon flow in the tropical Mandovi and Zuari estuaries (southwest...

  19. High efficiency light source using solid-state emitter and down-conversion material

    Science.gov (United States)

    Narendran, Nadarajah; Gu, Yimin; Freyssinier, Jean Paul

    2010-10-26

    A light emitting apparatus includes a source of light for emitting light; a down conversion material receiving the emitted light, and converting the emitted light into transmitted light and backward transmitted light; and an optic device configured to receive the backward transmitted light and transfer the backward transmitted light outside of the optic device. The source of light is a semiconductor light emitting diode, a laser diode (LD), or a resonant cavity light emitting diode (RCLED). The down conversion material includes one of phosphor or other material for absorbing light in one spectral region and emitting light in another spectral region. The optic device, or lens, includes light transmissive material.

  20. Thermal energy harvesting and solar energy conversion utilizing carbon-based nanomaterials

    Science.gov (United States)

    McCarthy, Patrick T.

    This dissertation provides details of carbon-based nanomaterial fabrication for applications in energy harvesting and generation. As energy demands increase, and concerns about mankind's environmental impact increase, alternative methods of generating energy will be widely researched. Carbon-based nanomaterials may be effective in such applications as their fabrication is often inexpensive and they have highly desirable electrical, mechanical, and thermal properties. Synthesis and characterization of carbon nanotube thermal interfaces on gadolinium foils is described herein. Total thermal interface resistances of carbon nanotube coated gadolinium were measured using a one-dimensional reference calorimeter technique, and the effect of hydrogen embrittlement on the magnetic properties of gadolinium foils is discussed. The samples generated in this study were consistently measured with reduced total thermal interface resistances of 55-70% compared to bare gadolinium. Characterization of gadolinium foils in a cooling device called a magneto thermoelectric generator was also performed. A gadolinium shuttle drives the device as it transitions between ferromagnetic and paramagnetic states. Reduced interface resistances from the carbon nanotube arrays led to increased shuttle frequency and effective heat transfer coefficients. Detailed theoretical derivations for electron emission during thermal and photo-excitation are provided for both three-dimensional and two-dimensional materials. The derived theories were fitted to experimental data from variable temperature photoemission studies of potassium-intercalated graphitic nanopetals. A work function reduction from approximately 4.5 eV to 2 -- 3 eV resulted from potassium intercalation and adsorption. While changes in the electron energy distribution shape and intensity were significant within 310 -- 680 K, potassium-intercalated graphitic petals demonstrate very high thermal stability after heating to nearly 1000 K. Boron

  1. Highly efficient Cooper pair splitting with carbon nanotube quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Schindele, Jens; Baumgartner, Andreas; Schoenenberger, Christian [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    2012-07-01

    An elegant idea for the creation of entangled electrons in a solid-state device is to split spin-singlet Cooper pairs by coupling a superconductor to two parallel quantum dots (QDs) in a Y-junction geometry. Such Cooper pair splitting (CPS) was successfully detected in recent transport experiments on devices based on InAs nanowires and Carbon nanotubes (CNTs). Here we present experiments on a CNT based Cooper pair splitter device with low inter-dot tunnel coupling. We find an unprecedented splitting efficiency, often much larger than 50%, the upper limit in devices with large inter-dot coupling. Such CPS rates allow us to investigate this effect as a function of a variety of external parameters. In addition, we discuss Fano line-shapes as a feature of our QD resonances. A high CPS efficiency is a prerequisite for Bell state measurements, a clear way of proving that Cooper pairs can be extracted coherently and lead to spatially separated entangled electron pairs.

  2. An asymmetric broad waveguide structure for a 0.98-μm high-conversion-efficiency diode laser

    Institute of Scientific and Technical Information of China (English)

    Chong Feng; Wang Jun; Xiong Cong; Wang Cuiluan; Han Lin; Wu Peng; Wang Guan; Ma Xiaoyu

    2009-01-01

    A novel asymmetric broad waveguide diode laser structure was designed for high power conversion efficiency (PCE). The internal quantum efficiency, the series resistance, and the thermal resistance were theoretically optimized. The series resistance and the thermal resistance were greatly decreased by optimizing the thickness of the P-waveguide and the P-cladding layers. The internal quantum efficiency was increased by introducing a novel strain-compensated GaAs0.9P0.1/InGaAs quantum well. Experimentally, a single 1-cm bar with 20% fill factor and 900 μm cavity length was mounted P-side down on a microchannel-cooled heatsink, and a peak PCE of 60% is obtained at 26.3-W continuous wave output power. The results prove that this novel asymmetric waveguide structure design is an efficient approach to improve the PCE.

  3. Preparation and CO conversion activity of ceria nanotubes by carbon nanotubes templating method

    Institute of Scientific and Technical Information of China (English)

    FANG Jianhui; CAO Zhiyuan; ZHANG Dengsong; SHEN Xia; DING Weizhong; SHI Liyi

    2008-01-01

    Ceria nanotubes with high CO conversion activity by means of carbon nanotubes as removable templates in the simple liquid phase process were fabricated under moderate conditions. The pristine CNTs were first pretreated by refluxing in a 30% nitric acid solution at 140 °C for 24 h, then dispersed in an ethanolic Ce(NO3)3·6H2O solution with ultrasonic radiation at room temperature for 1 h. Under vigorous stirring, NaOH solution was added drop by drop into the above ethanolic solution until the pH value was 10. The product was collected and repeatedly washed with ethanol and on drying at 60 °C, the CeO2/CNT composites were obtained. Then, the as-prepared composites were heated at 450 °C in an air atmosphere for 30 min to remove CNTs. The ceria nanotubes were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-Ray Photoelectron Spectrum (XPS). The results showed that the ceria nanotubes were polycrystalline face-centered cubic phase and were composed of lots of dense ceria nanoparticles. The diameter of ceria nanotubes was about 40-50 nm. Catalytic activity of the product for CO oxidation was carried out at the region of 30-300 °C in a U-shaped quartz reactor with feeding about 0.15 g of the catalyst, which was loaded on Al2O3 carrier. The inlet gas composition was 1.0% CO and 28% O2 with N2 as balance, and the rate of flow was kept at 40 ml/min. The catalytic products were analyzed by gas chromatography. The as-prepared CeO2 nanotubes showed higher CO oxidation activity, which indicated that the morphology of ceria products affected the catalytic performance. The ceria nanotubes supported on Al2O3 demonstrated that conversion temperature for CO oxidation to CO2 was lower than that for bulk catalysts.

  4. Holey tungsten oxynitride nanowires: novel anodes efficiently integrate microbial chemical energy conversion and electrochemical energy storage.

    Science.gov (United States)

    Yu, Minghao; Han, Yi; Cheng, Xinyu; Hu, Le; Zeng, Yinxiang; Chen, Meiqiong; Cheng, Faliang; Lu, Xihong; Tong, Yexiang

    2015-05-20

    Holey tungsten oxynitride nanowires with superior conductivity, good biocompatibility, and good stability achieve excellent performance as anodes for both asymmetric supercapacitors and microbial fuel cells. Moreover, an innovative system is devised based on these as-prepared tungsten oxynitride anodes, which can simultaneously realize both energy conversion from chemical to electric energy and its storage. PMID:25854325

  5. Effect of Native Oxide Film on Commercial Magnesium Alloys Substrates and Carbonate Conversion Coating Growth and Corrosion Resistance

    Directory of Open Access Journals (Sweden)

    Sebastián Feliu, Jr.

    2014-03-01

    Full Text Available Possible relations between the native oxide film formed spontaneously on the AZ31 and AZ61 magnesium alloy substrates with different surface finish, the chemistry of the outer surface of the conversion coatings that grows after their subsequent immersion on saturated aqueous NaHCO3 solution treatment and the enhancement of corrosion resistance have been studied. The significant increase in the amount of aluminum and carbonate compounds on the surface of the conversion coating formed on the AZ61 substrate in polished condition seems to improve the corrosion resistance in low chloride ion concentration solutions. In contrast, the conversion coatings formed on the AZ31 substrates in polished condition has little effect on their protective properties compared to the respective as-received surface.

  6. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans

    Directory of Open Access Journals (Sweden)

    Anne M. Henstra

    2011-01-01

    Full Text Available Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently low levels of CO are reached. Here we study CO conversion and final CO levels in cultures of C. hydrogenoformans grown in batch cultures that were started with a 100% CO gas phase with and without removal of formed CO2. Final CO levels were 117 ppm without CO2 removal and below 2 ppm with CO2 removal. The Gibbs free energy change calculated with measured end concentrations and the detection of acetate suggest that C. hydrogenoformans shifted from a hydrogenogenic to an acetogenic metabolism.

  7. Sn-MCM-41 as Efficient Catalyst for the Conversion of Glucose into 5-Hydroxymethylfurfural in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Qing Xu

    2013-11-01

    Full Text Available Recently, much attention has been paid to the development of technologies that facilitate the conversion of biomass into platform chemicals such as 5-hydroxymethylfurfural (5-HMF. In this paper, a tin-containing silica molecular sieve (Sn-MCM-41 was found to act as a bifunctional heterogeneous catalyst for the efficient conversion of glucose into 5-HMF in ionic liquid. In the presence of [EMIM]Br, the yield of 5-HMF converted from glucose reached 70% at 110 °C after 4 h. During the reaction, the active center of the catalyst first catalyzed the isomerization of glucose into fructose and then the dehydration of fructose into 5-HMF. After the reaction, the heterogeneous catalyst Sn-MCM-41 could be easily recovered and reused without a significant loss in activity. The catalyst Sn-MCM-41 was also able to catalyze the conversion of fructose into 5-HMF at an 80% yield. Moreover, the low toxicity of the Sn-based catalyst makes the method a greener approach for the conversion of saccharides into 5-HMF.

  8. Environmental remediation and conversion of carbon dioxide (CO(2)) into useful green products by accelerated carbonation technology.

    Science.gov (United States)

    Lim, Mihee; Han, Gi-Chun; Ahn, Ji-Whan; You, Kwang-Suk

    2010-01-01

    This paper reviews the application of carbonation technology to the environmental industry as a way of reducing carbon dioxide (CO(2)), a green house gas, including the presentation of related projects of our research group. An alternative technology to very slow natural carbonation is the co-called 'accelerated carbonation', which completes its fast reaction within few hours by using pure CO(2). Carbonation technology is widely applied to solidify or stabilize solid combustion residues from municipal solid wastes, paper mill wastes, etc. and contaminated soils, and to manufacture precipitated calcium carbonate (PCC). Carbonated products can be utilized as aggregates in the concrete industry and as alkaline fillers in the paper (or recycled paper) making industry. The quantity of captured CO(2) in carbonated products can be evaluated by measuring mass loss of heated samples by thermo-gravimetric (TG) analysis. The industrial carbonation technology could contribute to both reduction of CO(2) emissions and environmental remediation.

  9. Characterization of surface carbon formed during the conversion of methane to benzene over Mo/H-ZSM-5 catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Rosynek, Michael P.; Lunsford, Jack H.

    2001-01-01

    During the conversion of methane to benzene in the absence of oxygen over a 2 wt% Mo/H-ZSM-5 catalyst at 700 °C, three different types of surface carbon have been observed by X-ray photoelectron spectroscopy: adventitious or graphitic-like C (284.6 eV), carbidic-like C (282.7 eV), and hydrogen-poor

  10. Solar Energy Conversion by Dye-Sensitized Photovoltaic Cells Using High Surface Area Mesoporous Carbon Counter Electrode

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available Development of new counter electrode materials is vital for commercialization of efficient dye-sensitized solar cells (DSCs process. Research on DSCs has been focused mainly on using platinum as counter electrode, which makes them expensive. In this paper, we report DSCs fabricated with high surface area mesoporous carbon thin film with uniform spherical particles as counter electrode. An overall light-to-electricity efficiency as high as 7.6% has been achieved under illumination of air mass (AM 1.5 sunlight (100 mW/cm2. In comparison with activated carbon, high surface area mesoporous carbon shows superior performance. Our results show that mesoporous carbon with high specific surface area and uniform pore size distribution proved to be better efficient electrode material for DSCs.

  11. Ordered crystalline TiO2 nanohexagon arrays for improving conversion efficiency of dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Anatase TiO2 nanohexagon arrays were grown by using an anodization process of Ti foil in fluoride containing electrolytes. Photoanode based on the as-grown anatase TiO2 nanohexagon arrays for DSSCs showed a power photoconversion efficiency of 4.01% and incident photon-to-current conversion efficiency of 68%, which are significantly higher than those of the device based on anatase TiO2 nanotube arrays. This improvement in power conversion efficiency should be attributed to the fact that the nanotubes with hexagonal structure have higher surface area to allow the uploading of more dye molecules for light harvesting. Also, the spacing introduced inside the hexagon might allow the dye molecules to cover the interior of the walls. In addition, it is believed that the photoconversion efficiency can be further increased by optimizing the hexagonal structure through the electrochemical conditions. - Graphical abstract: Nanotubes with hexagonal structure have higher surface area to allow the uploading of more dye molecules for light harvesting in dye-sensitized solar cells. - Highlights: • A unique TiO2 nanohexagon arrays were grown by an anodization process. • Higher surface area for dye uploading provided by the hexagon structure. • TiO2 nanohexagon based photoanode has PCE of 4.01% and IPCE of 68%

  12. Ordered crystalline TiO{sub 2} nanohexagon arrays for improving conversion efficiency of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Javed, Hafiz Muhammad Asif [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Yin, Xingtian; Xing, Yonglei; Liu, Xiaobin; Asghar, Ali; Shao, Jinyou [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China); Kong, Ling Bing, E-mail: ELBKong@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 (Singapore)

    2015-10-15

    Anatase TiO{sub 2} nanohexagon arrays were grown by using an anodization process of Ti foil in fluoride containing electrolytes. Photoanode based on the as-grown anatase TiO{sub 2} nanohexagon arrays for DSSCs showed a power photoconversion efficiency of 4.01% and incident photon-to-current conversion efficiency of 68%, which are significantly higher than those of the device based on anatase TiO{sub 2} nanotube arrays. This improvement in power conversion efficiency should be attributed to the fact that the nanotubes with hexagonal structure have higher surface area to allow the uploading of more dye molecules for light harvesting. Also, the spacing introduced inside the hexagon might allow the dye molecules to cover the interior of the walls. In addition, it is believed that the photoconversion efficiency can be further increased by optimizing the hexagonal structure through the electrochemical conditions. - Graphical abstract: Nanotubes with hexagonal structure have higher surface area to allow the uploading of more dye molecules for light harvesting in dye-sensitized solar cells. - Highlights: • A unique TiO{sub 2} nanohexagon arrays were grown by an anodization process. • Higher surface area for dye uploading provided by the hexagon structure. • TiO{sub 2} nanohexagon based photoanode has PCE of 4.01% and IPCE of 68%.

  13. Non-native Co-, Mn-, and Ti-oxyhydroxide nanocrystals in ferritin for high efficiency solar energy conversion.

    Science.gov (United States)

    Erickson, S D; Smith, T J; Moses, L M; Watt, R K; Colton, J S

    2015-01-01

    Quantum dot solar cells seek to surpass the solar energy conversion efficiencies achieved by bulk semiconductors. This new field requires a broad selection of materials to achieve its full potential. The 12 nm spherical protein ferritin can be used as a template for uniform and controlled nanocrystal growth, and to then house the nanocrystals for use in solar energy conversion. In this study, precise band gaps of titanium, cobalt, and manganese oxyhydroxide nanocrystals within ferritin were measured, and a change in band gap due to quantum confinement effects was observed. The range of band gaps obtainable from these three types of nanocrystals is 2.19-2.29 eV, 1.93-2.15 eV, and 1.60-1.65 eV respectively. From these measured band gaps, theoretical efficiency limits for a multi-junction solar cell using these ferritin-enclosed nanocrystals are calculated and found to be 38.0% for unconcentrated sunlight and 44.9% for maximally concentrated sunlight. If a ferritin-based nanocrystal with a band gap similar to silicon can be found (i.e. 1.12 eV), the theoretical efficiency limits are raised to 51.3% and 63.1%, respectively. For a current matched cell, these latter efficiencies become 41.6% (with an operating voltage of 5.49 V), and 50.0% (with an operating voltage of 6.59 V), for unconcentrated and maximally concentrated sunlight respectively. PMID:25490522

  14. The Greenhouse Gas Flux and Carbon Budget of Land Use Conversion from Pasture to Energy Cane Production

    Science.gov (United States)

    Duval, B.; Davis, S. C.; Parton, W. J.; Long, S. P.; DeLucia, E. H.

    2011-12-01

    The United States is committed to produce 140 billion liters of ethanol by 2022. To meet this goal, and mitigate concerns about the "fuel versus food" conundrum, there is a pressing need for a second generation of sustainable biofuel feedstocks. Energy cane is a high yield, cold-tolerant C4 grass that can be efficiently used to produce bio-ethanol via existing cellulo-lignosic conversion technologies. There is exciting promise for Energy cane as an ethanol feedstock, however the climate implications of large-scale land use change from pasture (a significant use of land in the Southeastern USA) to production of an energy grass has not been fully explored. Furthermore, the soil type on which Energy cane will be grown will likely have a significant impact on greenhouse gases (GHG). We use DAYCENT, a process based biogeochemical model, to forecast how land use change from pasture to Energy cane production influences ecosystem level GHG flux and soil carbon flux. Because Energy cane is not widely cultivated, we use the available sugar cane literature to validate our in silico experiments. DAYCENT simulations suggest that soil type and fertilization rates have a strong control on the GHG and soil C dynamics after changing land from pasture to Energy cane. Our model results show net losses of ecosystem level C when Energy cane is grown on Histosols (organic matter rich soils), and a net gain of ecosystem C when that crop is grown on Spodosols (sandy soils). Respired CO2, N2O and total GHG efflux is significantly higher on Histosols compared to Spodosols in cane production. We conclude that the soil type on which Energy cane is grown determines the climatic impact of changing a landscape from pasture to Energy cane, and the greatest long-term climate benefit comes from growing cane on Spodosols.

  15. Graphitic Carbon Nitride/Nitrogen-Rich Carbon Nanofibers: Highly Efficient Photocatalytic Hydrogen Evolution without Cocatalysts.

    Science.gov (United States)

    Han, Qing; Wang, Bing; Gao, Jian; Qu, Liangti

    2016-08-26

    An interconnected framework of mesoporous graphitic-C3 N4 nanofibers merged with in situ incorporated nitrogen-rich carbon has been prepared. The unique composition and structure of the nanofibers as well as strong coupling between the components endow them with efficient light-harvesting properties, improved charged separation, and a multidimensional electron transport path that enhance the performance of hydrogen production. The as-obtained catalyst exhibits an extremely high hydrogen-evolution rate of 16885 μmol h(-1)  g(-1) , and a remarkable apparent quantum efficiency of 14.3 % at 420 nm without any cocatalysts, which is much higher than most reported g-C3 N4 -based photocatalysts even in the presence of Pt-based cocatalysts.

  16. Efficient conversion of acetate into lipids by the oleaginous yeast Cryptococcus curvatus

    OpenAIRE

    Gong, Zhiwei; Shen, Hongwei; Zhou, Wengting; Wang, Yandan; Yang, Xiaobing; Zhao, Zongbao K.

    2015-01-01

    Background Acetic acid is routinely generated during lignocelluloses degradation, syngas fermentation, dark hydrogen fermentation and other anaerobic bioprocesses. Acetate stream is commonly regarded as a by-product and detrimental to microbial cell growth. Conversion of acetate into lipids by oleaginous yeasts may be a good choice to turn the by-product into treasure. Results Ten well-known oleaginous yeasts were evaluated for lipid production on acetate under flask culture conditions. It wa...

  17. Adaptive Critic Based Neuro-Fuzzy Tracker for Improving Conversion Efficiency in PV Solar Cells

    OpenAIRE

    Halimeh Rashidi; Saeed Niazi; Jamshid Khorshidi

    2012-01-01

    The output power of photovoltaic systems is directly related to the amount of solar energy collected by the system and it is therefore necessary to track the sun’s position with high accuracy. This study proposes multi-agent adaptive critic based nero fuzzy solar tracking system dedicated to PV panels. The proposed tracker ensures the optimal conversion of solar energy into electricity by properly adjusting the PV panels according to the position of the sun. To evaluate the usefulness of the ...

  18. Environmental Remediation and Conversion of Carbon Dioxide (CO2 into Useful Green Products by Accelerated Carbonation Technology

    Directory of Open Access Journals (Sweden)

    Kwang-Suk You

    2010-01-01

    Full Text Available This paper reviews the application of carbonation technology to the environmental industry as a way of reducing carbon dioxide (CO2, a green house gas, including the presentation of related projects of our research group. An alternative technology to very slow natural carbonation is the co-called ‘accelerated carbonation’, which completes its fast reaction within few hours by using pure CO2. Carbonation technology is widely applied to solidify or stabilize solid combustion residues from municipal solid wastes, paper mill wastes, etc. and contaminated soils, and to manufacture precipitated calcium carbonate (PCC. Carbonated products can be utilized as aggregates in the concrete industry and as alkaline fillers in the paper (or recycled paper making industry. The quantity of captured CO2 in carbonated products can be evaluated by measuring mass loss of heated samples by thermo-gravimetric (TG analysis. The industrial carbonation technology could contribute to both reduction of CO2 emissions and environmental remediation.

  19. Synthesis of a Sulfonated Two-Dimensional Covalent Organic Framework as an Efficient Solid Acid Catalyst for Biobased Chemical Conversion.

    Science.gov (United States)

    Peng, Yongwu; Hu, Zhigang; Gao, Yongjun; Yuan, Daqiang; Kang, Zixi; Qian, Yuhong; Yan, Ning; Zhao, Dan

    2015-10-12

    Because of limited framework stability tolerance, de novo synthesis of sulfonated covalent organic frameworks (COFs) remains challenging and unexplored. Herein, a sulfonated two-dimensional crystalline COF, termed TFP-DABA, was synthesized directly from 1,3,5-triformylphloroglucinol and 2,5-diaminobenzenesulfonic acid through a previously reported Schiff base condensation reaction, followed by irreversible enol-to-keto tautomerization, which strengthened its structural stability. TFP-DABA is a highly efficient solid acid catalyst for fructose conversion with remarkable yields (97 % for 5-hydroxymethylfurfural and 65 % for 2,5-diformylfuran), good chemoselectivity, and good recyclability. The present study sheds light on the de novo synthesis of sulfonated COFs as novel solid acid catalysts for biobased chemical conversion.

  20. Synthesis of a Sulfonated Two-Dimensional Covalent Organic Framework as an Efficient Solid Acid Catalyst for Biobased Chemical Conversion.

    Science.gov (United States)

    Peng, Yongwu; Hu, Zhigang; Gao, Yongjun; Yuan, Daqiang; Kang, Zixi; Qian, Yuhong; Yan, Ning; Zhao, Dan

    2015-10-12

    Because of limited framework stability tolerance, de novo synthesis of sulfonated covalent organic frameworks (COFs) remains challenging and unexplored. Herein, a sulfonated two-dimensional crystalline COF, termed TFP-DABA, was synthesized directly from 1,3,5-triformylphloroglucinol and 2,5-diaminobenzenesulfonic acid through a previously reported Schiff base condensation reaction, followed by irreversible enol-to-keto tautomerization, which strengthened its structural stability. TFP-DABA is a highly efficient solid acid catalyst for fructose conversion with remarkable yields (97 % for 5-hydroxymethylfurfural and 65 % for 2,5-diformylfuran), good chemoselectivity, and good recyclability. The present study sheds light on the de novo synthesis of sulfonated COFs as novel solid acid catalysts for biobased chemical conversion. PMID:26448524

  1. Committed carbon emissions, deforestation, and community land conversion from oil palm plantation expansion in West Kalimantan, Indonesia.

    Science.gov (United States)

    Carlson, Kimberly M; Curran, Lisa M; Ratnasari, Dessy; Pittman, Alice M; Soares-Filho, Britaldo S; Asner, Gregory P; Trigg, Simon N; Gaveau, David A; Lawrence, Deborah; Rodrigues, Hermann O

    2012-05-01

    Industrial agricultural plantations are a rapidly increasing yet largely unmeasured source of tropical land cover change. Here, we evaluate impacts of oil palm plantation development on land cover, carbon flux, and agrarian community lands in West Kalimantan, Indonesian Borneo. With a spatially explicit land change/carbon bookkeeping model, parameterized using high-resolution satellite time series and informed by socioeconomic surveys, we assess previous and project future plantation expansion under five scenarios. Although fire was the primary proximate cause of 1989-2008 deforestation (93%) and net carbon emissions (69%), by 2007-2008, oil palm directly caused 27% of total and 40% of peatland deforestation. Plantation land sources exhibited distinctive temporal dynamics, comprising 81% forests on mineral soils (1994-2001), shifting to 69% peatlands (2008-2011). Plantation leases reveal vast development potential. In 2008, leases spanned ∼65% of the region, including 62% on peatlands and 59% of community-managed lands, yet lands are cleared for oil palm, generating 26% of net carbon emissions. Intact forest cover declines to 4%, and the proportion of emissions sourced from peatlands increases 38%. Prohibiting intact and logged forest and peatland conversion to oil palm reduces emissions only 4% below BAU, because of continued uncontrolled fire. Protecting logged forests achieves greater carbon emissions reductions (21%) than protecting intact forests alone (9%) and is critical for mitigating carbon emissions. Extensive allocated leases constrain land management options, requiring trade-offs among oil palm production, carbon emissions mitigation, and maintaining community landholdings.

  2. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

    Science.gov (United States)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1993-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

  3. Limiting efficiencies of GaInP/GaAs/Ge up-conversion systems: Addressing the issue of radiative coupling

    Science.gov (United States)

    Lan, Dongchen; Green, Martin A.

    2016-09-01

    Recent work proposed up-conversion of sunlight through low-band-gap solar cells in combination with a large-band-gap light-emitting diode (LED), with one possibility being the use of a GaAs/Ge tandem photovoltaic device to drive a GaInP LED. One-sun limiting efficiencies for a GaInP bifacial solar cell with such an up-converter attached to its rear are reported for varying band-gap of GaInP junctions, both when there are radiative couplings between cells in the rear up-converter and when there are not. With a maximum theoretical efficiency of 44%, it is shown that the top cell's band-gap is a trade-off and radiative coupling in the rear up-converter reduces the efficiency, where physical reasons are given as is insight into the practice.

  4. New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

    CERN Document Server

    Wang, DongLin

    2014-01-01

    Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350nm-800nm, the conversion efficiency of solar cells can be further enhanced.

  5. Efficiency of a gyroscopic device for conversion of mechanical wave energy to electrical energy

    DEFF Research Database (Denmark)

    Carlsen, Martin; Darula, Radoslav; Gravesen, Jens;

    2011-01-01

    We consider a recently proposed gyroscopic device for conversion of mechanical ocean wave energy to electrical energy. Two models of the device derived from standard engineering mechanics from the literature are analysed, and a model is derived from analytical mechanics considerations. From...... these models, estimates of the power production, eciency, forces and moments are made. We nd that it is possible to extract a signicant amount of energy from an ocean wave using the described device. Further studies are required for a full treatment of the device....

  6. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    Science.gov (United States)

    Ledru, G.; Catalano, C.; Dupuis, P.; Zissis, G.

    2014-10-01

    A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor's thickness and operating current of the laser diode over the (x, y) chromaticity coordinates, Correlated Color Temperature (CCT) and Color Rendering Index (CRI). The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

  7. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    Directory of Open Access Journals (Sweden)

    G. Ledru

    2014-10-01

    Full Text Available A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y chromaticity coordinates, Correlated Color Temperature (CCT and Color Rendering Index (CRI. The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

  8. Catalytic conversion of xylose and corn stalk into furfural over carbon solid acid catalyst in γ-valerolactone.

    Science.gov (United States)

    Zhang, Tingwei; Li, Wenzhi; Xu, Zhiping; Liu, Qiyu; Ma, Qiaozhi; Jameel, Hasan; Chang, Hou-min; Ma, Longlong

    2016-06-01

    A novel carbon solid acid catalyst was synthesized by the sulfonation of carbonaceous material which was prepared by carbonization of sucrose using 4-BDS as a sulfonating agent. TEM, N2 adsorption-desorption, elemental analysis, XPS and FT-IR were used to characterize the catalyst. Then, the catalyst was applied for the conversion of xylose and corn stalk into furfural in GVL. The influence of the reaction time, temperature and dosage of catalyst on xylose dehydration were also investigated. The Brønsted acid catalyst exhibited high activity in the dehydration of xylose, with a high furfural yield of 78.5% at 170°C in 30min. What's more, a 60.6% furfural yield from corn stalk was achieved in 100min at 200°C. The recyclability of the sulfonated carbon catalyst was perfect, and it could be reused for 5times without the loss of furfural yields.

  9. Efficient Solar Energy Conversion Using CaCu3Ti4O12 Photoanode for Photocatalysis and Photoelectrocatalysis

    OpenAIRE

    H. S. Kushwaha; Niyaz A Madhar; B. Ilahi; Thomas, P; Aditi Halder; Rahul Vaish

    2016-01-01

    A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm2, indicating the visible...

  10. High and Stable Conversion Efficiency Obtaining in Single-Stage Multi-Crystal Optical Parametric Chirped Pulse Amplification System

    Institute of Scientific and Technical Information of China (English)

    JIANG Yong-Liang; LENG Yu-Xin; ZHAO Bao-Zhen; WANG Cheng; LIANG Xiao-Yan; LU Hai-He; XU Zhi-Zhan

    2005-01-01

    @@ An optical parametric chirped-pulse amplification system is demonstrated to provide 32.9% pump-to-signal con-version efficiency. Special techniques are used to make the signal and pump pulses match with each other inboth spectral and temporal domains. The broadband 9.5-mJ pulses are produced at the repetition rate of 1 Hzwith the gain of over 1.9 × 108. The output energy fluctuation of 7.8% is achieved for the saturated amplificationprocess against the pump fluctuation of 10%.

  11. Grating-structured freestanding triboelectric-layer nanogenerator for harvesting mechanical energy at 85% total conversion efficiency.

    Science.gov (United States)

    Xie, Yannan; Wang, Sihong; Niu, Simiao; Lin, Long; Jing, Qingshen; Yang, Jin; Wu, Zhengyun; Wang, Zhong Lin

    2014-10-01

    A newly-designed triboelectric nanogenerator is demonstrated which is composed of a grating-segmented freestanding triboelectric layer and two groups of interdigitated electrodes with the same periodicity. The sliding motion of the grating units across the electrode fingers can be converted into multiple alternating currents through the external load due to the contact electrification and electrostatic induction. Working in non-contact mode, the device shows excellent stability and the total conversion efficiency can reach up to 85% at low operation frequency. PMID:25156128

  12. Integrated four-channel all-fiber up-conversion single-photon-detector with adjustable efficiency and dark count

    CERN Document Server

    Zheng, Ming-Yang; Ma, Fei; Zhou, Fei; Zhang, Hai-Ting; Dai, Yun-Qi; Xie, Xiuping; Zhang, Qiang; Pan, Jian-Wei

    2016-01-01

    Up-conversion single photon detector (UCSPD) has been widely used in many research fields including quantum key distribution (QKD), lidar, optical time domain reflectrometry (OTDR) and deep space communication. For the first time in laboratory, we have developed an integrated four-channel all-fiber UCSPD which can work in both free-running and gate modes. This compact module can satisfy different experimental demands with adjustable detection efficiency and dark count. We have characterized the key parameters of the UCSPD system.

  13. Development of a Supercritical Carbon Dioxide Brayton Cycle: Improving VHTR Efficiency and Testing Material Compatibility - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chang H. Oh

    2006-06-01

    Generation IV reactors will need to be intrinsically safe, having a proliferation-resistant fuel cycle and several advantages relative to existing light water reactor (LWR). They, however, must still overcome certain technical issues and the cost barrier before it can be built in the U.S. The establishment of a nuclear power cost goal of 3.3 cents/kWh is desirable in order to compete with fossil combined-cycle, gas turbine power generation. This goal requires approximately a 30 percent reduction in power cost for stateof-the-art nuclear plants. It has been demonstrated that this large cost differential can be overcome only by technology improvements that lead to a combination of better efficiency and more compatible reactor materials. The objectives of this research are (1) to develop a supercritical carbon dioxide Brayton cycle in the secondary power conversion side that can be applied to the Very-High-Temperature Gas-Cooled Reactor (VHTR), (2) to improve the plant net efficiency by using the carbon dioxide Brayton cycle, and (3) to test material compatibility at high temperatures and pressures. The reduced volumetric flow rate of carbon dioxide due to higher density compared to helium will reduce compression work, which eventually increase plant net efficiency.

  14. Alkali metal carbon dioxide electrochemical system for energy storage and/or conversion of carbon dioxide to oxygen

    Science.gov (United States)

    Hagedorn, Norman H. (Inventor)

    1993-01-01

    An alkali metal, such as lithium, is the anodic reactant; carbon dioxide or a mixture of carbon dioxide and carbon monoxide is the cathodic reactant; and carbonate of the alkali metal is the electrolyte in an electrochemical cell for the storage and delivery of electrical energy. Additionally, alkali metal-carbon dioxide battery systems include a plurality of such electrochemical cells. Gold is a preferred catalyst for reducing the carbon dioxide at the cathode. The fuel cell of the invention produces electrochemical energy through the use of an anodic reactant which is extremely energetic and light, and a cathodic reactant which can be extracted from its environment and therefore exacts no transportation penalty. The invention is, therefore, especially useful in extraterrestrial environments.

  15. Time-resolved optical spectroscopy on Er-doped fluorozirconate-based glasses for efficient up-conversion

    International Nuclear Information System (INIS)

    Fluorozirconate(FZ)-based glasses have shown their potential as hosts for rare-earth (RE) ions such as Er, in these glasses REs show emissions that would be quenched in other glasses. Such material systems are of practical interest for photon up-conversion. For photovoltaic applications, the efficiency of bifacial solar cells could be vastly improved by an up-converting back layer. Up-conversion is the sequential absorption of two or more low-energy infrared photons by a RE ion followed by subsequent emission of a visible photon. This process is dependent on the intermediate level lifetime of the RE ion, which is determined by the phonon energies of the host material. Low phonon energy glasses like FZ glasses are thus desirable hosts. The lifetimes of the energy levels involved in the up-conversion process are investigated by time-resolved spectroscopy. Short laser pulses at different wavelengths are used for excitation; the emissions are detected via time-correlated photon counting. The radiative and non-radiative decay processes in Er-doped FZ glasses are analyzed and discussed.

  16. Environmental and energy efficiency evaluation of straw treatment and conversion technology

    OpenAIRE

    Kalinauskaitė, Solveiga

    2014-01-01

    Research goal. We seek to validate optimal composition of straw biomass fuel and energy efficiency of straw utilization for energy needs, to assess straw biomass fuel preparation technology in respect to energy efficiency, and to determine emissions that are generated during straw combustion. Research objectives. The following objectives were planned to reach the goal of the research: 1) Process analysis of preparation of biomass fuel (pellets and briquettes) for burning, 2) Validation of mix...

  17. Study on an environmental-friendly and high-efficient fuel cell energy conversion system

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The kinds and the distribution of the coal in China areinvestigated in this paper. The results indicated that the 80% coalin China is used by the method of the coal gasification. Thepossibility of utilization and development of the fuel cell powerplant in China is analyzed. A combined cycle generation system isdesigned. Its net electrical efficiency is about 55%(LHV), which ishigher than that of the fire power plant. So it isenvironmental-friendly and high-efficient generation mode.

  18. Design of environment-friendly and next generation-type conversion system for unused carbon resources by developing highly functional materials; Kokino zairyo kaihatsu ni yoru kankyo chowagata jisedai miriyo tanso shigen tenkan system no kochiku

    Energy Technology Data Exchange (ETDEWEB)

    Wakabayashi, K.; Morooka, S.; Arai, Y. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Sakanishi, K. [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1997-02-01

    Studies are conducted for the development of now-unused kinds of fossil carbon resources, such as low rank coal and heavy gravity crude oil, into higher-value liquid fuel. In the preliminary treatment process, the fossil carbon resources are dried by use of supercritical carbon dioxide, when it is found that the resources are disintegrated and water is desorbed. In a low rank coal liquefaction process using the NiMo/KB (Kefjen Black) catalyst, more than 60% is converted into oil, which rate is improved by use of the dual-temperature liquefaction process. This catalyst may be recovered by separation utilizing specific gravity difference. As a low temperature gasification catalyst, the alkaline carbonate-carried carbon catalyst is very quick at the initial stage of reaction. The perovskite-carried alkaline carbonate catalyst is high in carbon oxidizing/activating efficiency at low temperatures. The silica film deposited on an alumina-coated support tube is excellent in selectivity and speed as a hydrogen separating film, and a carbonized polyimide film as a carbon dioxide separating film. For the supercritical phase adsorption/separation of chemicals not to be distilled easily, the NaY-type zeolite functions effectively. Pd/ZrO2 serving as a carbon monoxide conversion catalyst enables the recovery of more MeOH when Pd grains are smaller in diameter.

  19. Designing nitrogen-enriched echinus-like carbon capsules for highly efficient oxygen reduction reaction and lithium ion storage.

    Science.gov (United States)

    Hu, Chuangang; Wang, Lixia; Zhao, Yang; Ye, Minhui; Chen, Qing; Feng, Zhihai; Qu, Liangti

    2014-07-21

    Both structural and compositional modulations are important for high-performance electrode materials in energy conversion/storage devices. Here hierarchical-structure nitrogen-rich hybrid porous carbon capsules with bamboo-like carbon nanotube whiskers (N-CC@CNTs) grown in situ have been specifically designed, which combine the advantageous features of high surface area, abundant active sites, easy access to medium and favorable mass transport. As a result, the newly prepared N-CC@CNTs show highly efficient catalytic activity in oxygen reduction reaction in alkaline media for fuel cells, which not only outperforms commercial Pt-based catalysts in terms of kinetic limiting current, stability and tolerance to methanol crossover effect, but is also better than most of the nanostructured carbon-based catalysts reported previously. On the other hand, as an anode material for lithium ion batteries, the N-CC@CNTs obtained also exhibit an excellent reversible capacity of ca. 1337 mA h g(-1) at 0.5 A g(-1), outstanding rate capability and long cycling stability, even at a current density of 20 A g(-1). The capacity is the highest among all the heteroatom-doped carbon materials reported so far, and is even higher than that of many of the composites of metal, metal oxides or metal sulfides with carbon materials. PMID:24906180

  20. HE CONVERSION OF THE EFFICIENCY OF LABOR, RESPECTIVELY OF LABOR PRODUCTIVITY IN THE ECONOMIC AND COMMERCIAL RATE OF RETURN

    Directory of Open Access Journals (Sweden)

    Constantin CĂRUNTU

    2010-12-01

    Full Text Available Generally, an activity is considered to be efficient if the production implies low costs or if the revenues from selling the products on the market outweigh the expenditures that were made to achieve them. Labor productivity as an efficiency indicator of a production process represents an expression of the relationship between effect (products, services and effort (work means, labor force, work items. Through the labor productivity conversion in rates of return (economic and commercial is determined an evolution and an influence on these rates, driving the company’s own efforts to innovate, produce and harness goods, works and services with maximum utility, efficiency and competitiveness services. The aim of this paper is to highlight the work efficiency, respectively the labor productivity detached from the factorial context in the trade and economic rates of return. The introduction presents some general aspects referring to labor productivity, then it will be presented and discussed the analytical methods used in the process of reflecting the labor productivity in the rates of return, the results analysis, and at the end of this paper it will be presented some conclusions based on the study case. The expected results consist in identifying the mechanisms by which labor efficiency is converted into the company’s economic and financial performance.

  1. Adaptive Critic Based Neuro-Fuzzy Tracker for Improving Conversion Efficiency in PV Solar Cells

    Directory of Open Access Journals (Sweden)

    Halimeh Rashidi

    2012-08-01

    Full Text Available The output power of photovoltaic systems is directly related to the amount of solar energy collected by the system and it is therefore necessary to track the sun’s position with high accuracy. This study proposes multi-agent adaptive critic based nero fuzzy solar tracking system dedicated to PV panels. The proposed tracker ensures the optimal conversion of solar energy into electricity by properly adjusting the PV panels according to the position of the sun. To evaluate the usefulness of the proposed method, some computer simulations are performed and compared with fuzzy PD controller. Obtained results show the proposed control strategy is very robust, flexible and could be used to get the desired performance levels. The response time is also very fast. Simulation results that have been compared with fuzzy PD controller show that our method has the better control performance than fuzzy PD controller.

  2. Advances with vertical epitaxial heterostructure architecture (VEHSA) phototransducers for optical to electrical power conversion efficiencies exceeding 50 percent

    Science.gov (United States)

    Fafard, S.; Proulx, F.; York, M. C. A.; Wilkins, M.; Valdivia, C. E.; Bajcsy, M.; Ban, D.; Jaouad, A.; Bouzazi, B.; Arès, R.; Aimez, V.; Hinzer, K.; Masson, D. P.

    2016-03-01

    A monolithic compound semiconductor phototransducer optimized for narrow-band light sources was designed for and has achieved conversion efficiencies exceeding 50%. The III-V heterostructure was grown by MOCVD, based on the vertical stacking of a number of partially absorbing GaAs n/p junctions connected in series with tunnel junctions. The thicknesses of the p-type base layers of the diodes were engineered for optimal absorption and current matching for an optical input with wavelengths centered in the 830 nm to 850 nm range. The device architecture allows for improved open-circuit voltage in the individual base segments due to efficient carrier extraction while simultaneously maintaining a complete absorption of the input photons with no need for complicated fabrication processes or reflecting layers. Progress for device outputs achieving in excess of 12 V is reviewed in this study.

  3. 海洋鱼类的转换效率及其影响因子%A review of the conversion efficiency and its influencers in marine fishes

    Institute of Scientific and Technical Information of China (English)

    郭学武; 唐启升

    2004-01-01

    A review of conversion efficiency and its influencers in marine fishes is presented in this paper. The conversion efficiency is the efficiency of food utilization for growth, usually expressed as energy conversion efficiency, i. e, growth efficiency, when measured in energy, or food conversion efficiency when measured in biomass. So, estimation of conversion efficiency is basically a work on determinations of food consumption and weight growth of fish. Influence factor of conversion efficiency are mostly those influencing food consumption and weight growth, containing abiotic, biotic, and physiological factors, and limitations of controlled conditions in experiments, in many cases, which leads to results not reflecting the natural states. The abiotic influencers include water temperature, salinity, pH, dissolved oxygen, ammonia nitrogen, current surrounding, and photoperiod, of which water temperature and photoperiod are the most important. In experiments without food limitation, the growth rate of fish increases generally with rising of water temperature, and reaches a maximum at an optimum temperature. But that the optimum temperature for growth goes down at low ration levels indicates that the temperature influence on growth depends upon food availability for fishes. The photoperiod can speed up or keep down the fish growth with its alternation during a year. The biotic influencers contain food availability, competition, and predation. The food availability is considered as a key factor, as important as water temperature, manipulating food consumption and growth of fish, It is density dependent and is diversified temporally and spatially due to climate change, physical and chemical oceanography processes in the ecosystem. The availability of food that contains high calorie is a primary reason why food type shifts evidently the food conversion efficiency in a species of fish. Comparatively, the energy conversion efficiency is much more steady with the change of

  4. Efficient fabrication of carbon nanotube micro tip arrays by tailoring cross-stacked carbon nanotube sheets.

    Science.gov (United States)

    Wei, Yang; Liu, Peng; Zhu, Feng; Jiang, Kaili; Li, Qunqing; Fan, Shoushan

    2012-04-11

    Carbon nanotube (CNT) micro tip arrays with hairpin structures on patterned silicon wafers were efficiently fabricated by tailoring the cross-stacked CNT sheet with laser. A blade-like structure was formed at the laser-cut edges of the CNT sheet. CNT field emitters, pulled out from the end of the hairpin by an adhesive tape, can provide 150 μA intrinsic emission currents with low beam noise. The nice field emission is ascribed to the Joule-heating-induced desorption of the emitter surface by the hairpin structure, the high temperature annealing effect, and the surface morphology. The CNT emitters with hairpin structures will greatly promote the applications of CNTs in vacuum electronic devices and hold the promises to be used as the hot tips for thermochemical nanolithography. More CNT-based structures and devices can be fabricated on a large scale by this versatile method. PMID:22433000

  5. Non-native Co-, Mn-, and Ti-oxyhydroxide nanocrystals in ferritin for high efficiency solar energy conversion

    International Nuclear Information System (INIS)

    Quantum dot solar cells seek to surpass the solar energy conversion efficiencies achieved by bulk semiconductors. This new field requires a broad selection of materials to achieve its full potential. The 12 nm spherical protein ferritin can be used as a template for uniform and controlled nanocrystal growth, and to then house the nanocrystals for use in solar energy conversion. In this study, precise band gaps of titanium, cobalt, and manganese oxyhydroxide nanocrystals within ferritin were measured, and a change in band gap due to quantum confinement effects was observed. The range of band gaps obtainable from these three types of nanocrystals is 2.19–2.29 eV, 1.93–2.15 eV, and 1.60–1.65 eV respectively. From these measured band gaps, theoretical efficiency limits for a multi-junction solar cell using these ferritin-enclosed nanocrystals are calculated and found to be 38.0% for unconcentrated sunlight and 44.9% for maximally concentrated sunlight. If a ferritin-based nanocrystal with a band gap similar to silicon can be found (i.e. 1.12 eV), the theoretical efficiency limits are raised to 51.3% and 63.1%, respectively. For a current matched cell, these latter efficiencies become 41.6% (with an operating voltage of 5.49 V), and 50.0% (with an operating voltage of 6.59 V), for unconcentrated and maximally concentrated sunlight respectively. (paper)

  6. Solution-Processed Organic Solar Cells with Power Conversion Efficiencies of 2.5% using Benzothiadiazole/Imide-Based Acceptors

    KAUST Repository

    Bloking, Jason T.

    2011-12-27

    A new series of electron-deficient molecules based on a central benzothiadiazole moiety flanked with vinylimides has been synthesized via Heck chemistry and used in solution-processed organic photovoltaics (OPV). Two new compounds, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (PI-BT) and 4,7-bis(4-(N-hexyl-naphthalimide)vinyl)benzo[c]1,2,5-thiadiazole (NI-BT), show significantly different behaviors in bulk heterojunction (BHJ) solar cells using poly(3-hexylthiophene) (P3HT) as the electron donor. Two-dimensional grazing incidence X-ray scattering (2D GIXS) experiments demonstrate that PI-BT shows significant crystallization in spin-coated thin films, whereas NI-BT does not. Density functional theory (DFT) calculations predict that while PI-BT maintains a planar structure in the ground state, steric interactions cause a twist in the NI-BT molecule, likely preventing significant crystallization. In BHJ solar cells with P3HT as donor, PI-BT devices achieved a large open-circuit voltage of 0.96 V and a maximum device power-conversion efficiency of 2.54%, whereas NI-BT containing devices only achieved 0.1% power-conversion efficiency. © 2011 American Chemical Society.

  7. Effect of soybean diet: Growth and conversion efficiencies of fingerling of stinging cat fish, Heteropneustes fossilis (Bloch

    Directory of Open Access Journals (Sweden)

    Muzzammil Iqbal Siddiqui

    2014-04-01

    Full Text Available Replacement of 15% protein from soybean meal in Diet II was feasible for the stinging cat fish, Heteropneustes fossilis and no significant differences in growth parameters were found in fish fed soybean meal-based diets compared to those fed control diet (Diet I. Live weight gain percent (165% obtained in fish fed soybean meal based diet was not significantly different to that achieved (171% in fish fed Diet I. Specific growth rate percent, SGR (2.79%, feed conversion ratio FCR (1.40 and protein efficiency ratio PER (1.79 recorded in fish fed Diet II were also more less comparable to those fed control diet. Mortality was not recorded in the period of the feeding trial. Body composition of the fish fed soybean meal based diet (Diet II was also comparable to that fed control diet. Significantly higher fat content was noted in fish fed Diet II. However, the protein contents were not changed in fish fed Diet I and II. Similarly, no significant differences (P > 0.05 in protein productive value were noted between the two groups. However, ash content differed significantly (P < 0.05 in fish fed Diet I and II. Although soybean meal-based diet depressed growth and feed conversion efficiencies of the fish to some extent, inclusion of soybean meal was found to be cost-effective alternative to fish meal.

  8. Development of a data base for carbon dioxide releases resulting from conversion of land to agricultural uses

    Energy Technology Data Exchange (ETDEWEB)

    Richards, J.F.; Olson, J.S.

    1983-07-01

    Published information on worldwide conversion of land to regular agricultural uses for the periods 1860 to 1920 and 1920 to 1978 is summarized. New estimates are made for nation-by-nation conversion of land into permanent cropland. Estimated carbon content was tabulated for each type of vegetation removed. The estimated increased releases of CO/sub 2/ are presented by country or colony and by world region, and in a global summary for the two chronological periods. A global tabulation excluding Greenland and Antarctica, reveals that approximately 440 million hectares were converted to arable land between 1860 and 1920, increasing during 1920 to 1978 to 470 million hectares. Shrinkage of arable land within individual countries - which presumes reversion to woodland or lesser vegetation - totaled only 8.7 million hectares in the first period in contrast to 51 million hectares in the second period. Expansion of regularly cropped area resulted in releases of nearly 39 x 10/sup 9/ tons of carbon from the live plant mass during the 118-year period. Preliminary estimates of losses from oxidation of humus from the same area were smaller, amounting to about 23 x 10/sup 9/ tons of carbon.

  9. Improved conversion efficiency of amorphous Si solar cells using a mesoporous ZnO pattern

    Science.gov (United States)

    Go, Bit-Na; Kim, Yang Doo; suk Oh, Kyoung; Kim, Chaehyun; Choi, Hak-Jong; Lee, Heon

    2014-09-01

    To provide a front transparent electrode for use in highly efficient hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, porous flat layer and micro-patterns of zinc oxide (ZnO) nanoparticle (NP) layers were prepared through ultraviolet nanoimprint lithography (UV-NIL) and deposited on Al-doped ZnO (AZO) layers. Through this, it was found that a porous micro-pattern of ZnO NPs dispersed in resin can optimize the light-trapping pattern, with the efficiency of solar cells based on patterned or flat mesoporous ZnO layers increased by 27% and 12%, respectively.

  10. Efficient telecom to visible wavelength conversion in doubly resonant GaP microdisks

    CERN Document Server

    Lake, David P; Jayakumar, Harishankar; Santos, Laís Fujii dos; Curic, Davor; Barclay, Paul E

    2015-01-01

    Resonant second harmonic generation between 1550 nm and 775 nm with outside efficiency $> 4.4\\times10^{-4}\\, \\text{mW}^{-1}$ is demonstrated in a gallium phosphide microdisk cavity supporting high-$Q$ modes at visible ($Q \\sim 10^4$) and infrared ($Q \\sim 10^5$) wavelengths. The double resonance condition was satisfied through intracavity photothermal temperature tuning using $\\sim 360\\,\\mu$W of 1550 nm light input to a fiber taper and resonantly coupled to the microdisk. Above this pump power efficiency was observed to decrease. The observed behavior is consistent with a simple model for thermal tuning of the double resonance condition.

  11. Efficient telecom to visible wavelength conversion in doubly resonant gallium phosphide microdisks

    Science.gov (United States)

    Lake, David P.; Mitchell, Matthew; Jayakumar, Harishankar; dos Santos, Laís Fujii; Curic, Davor; Barclay, Paul E.

    2016-01-01

    Resonant second harmonic generation between 1550 nm and 775 nm with normalized outside efficiency > 3.8 × 10 - 4 mW - 1 is demonstrated in a gallium phosphide microdisk supporting high-Q modes at visible ( Q ˜ 10 4 ) and infrared ( Q ˜ 10 5 ) wavelengths. The double resonance condition is satisfied for a specific pump power through intracavity photothermal temperature tuning using ˜ 360 μ W of 1550 nm light input to a fiber taper and coupled to a microdisk resonance. Power dependent efficiency consistent with a simple model for thermal tuning of the double resonance condition is observed.

  12. Options for the Swedish steel industry - Energy efficiency measures and fuel conversion

    OpenAIRE

    Johansson, Maria; Söderström, Mats

    2011-01-01

    The processes of iron and steel making are energy intensive and consume large quantities of electricity and fossil fuels. In order to meet future climate targets and energy prices, the iron and steel industry has to improve its energy and resource efficiency. For the iron and steel industry to utilize its energy resources more efficiently and at the same time reduce its CO2 emissions a number of options are available. In this paper, opportunities for both integrated and scrap-based steel plan...

  13. Carbon Nanotube-based Nanohybrid Materials as Counter Electrode for Highly Efficient Dye-sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-Soo; Sim, Eun-Ju; Dao, Van-Duong; Choi, Ho-Suk [Chungnam National University, Daejeon (Korea, Republic of)

    2016-04-15

    In this study, we present an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic PtAu nanoparticles (NPs) on a multi-walled carbon nanotube (MWNT)-coated layer through dry plasma reduction. The NPs are stably and uniformly immobilized on the surface of MWNTs and the nanohybrid materials are applied to counter electrode (CE) of dye-sensitized solar cells (DSCs). The electrochemical properties of CEs are examined through cyclic voltammogram, electrochemical impedance spectroscopy, and Tafel measurements. As a result, both electrochemical catalytic activity and electrical conductivity are highest for PtAu/MWNT electrode. The DSC employing PtAu/MWNT CE exhibits power conversion efficiency of 7.9%. The efficiency is better than those of devices with MWNT (2.6%), AuNP/MWNT (2.7%) and PtNP/MWNT (7.5%) CEs.

  14. Facile synthesis of unique NiO nanostructures for efficiently catalytic conversion of CH4 at low temperature

    Science.gov (United States)

    Ye, Yucheng; Zhao, Yanting; Ni, Liuliu; Jiang, Kedan; Tong, Guoxiu; Zhao, Yuling; Teng, Botao

    2016-01-01

    A simple one-pot thermal decomposition approach to the selective synthesis of NiO nanomaterials was developed. The morphologies of the NiO nanomaterials were nanoparticle-based sheets, octahedra, nanosheet-built agglomerates, and nanoparticle-based microspheres. The samples were characterized by field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and N2 adsorption analyses. The morphology, crystal size, and texture properties of the products can be easily modulated by selecting various decomposition temperatures and precursors. Samples with high specific surface area and small crystal size were found to easily form at low sintering temperatures and when basic nickel carbonate and nickel oxalate dihydrate were used as precursors. Reduction property and CH4 conversion, as functions of decomposition temperature and precursor type, were systematically investigated. When NiCO3·2Ni(OH)2·4H2O and NiC2O4·2H2O were used as precursors, the as-obtained nanosheet-built agglomerates and nanoparticle-based sheets presented a high CH4 conversion rate because of the small crystal size and large specific surface area.

  15. Stability Constrained Efficiency Optimization for Droop Controlled DC-DC Conversion System

    DEFF Research Database (Denmark)

    Meng, Lexuan; Dragicevic, Tomislav; Guerrero, Josep M.;

    2013-01-01

    implementing tertiary regulation. Moreover, system dynamic is affected when shifting VRs. Therefore, the stability is considered in optimization by constraining the eigenvalues arising from dynamic state space model of the system. Genetic algorithm is used in searching for global efficiency optimum while...

  16. Bromine-catalyzed conversion of CO2 and epoxides to cyclic carbonates under continuous flow conditions.

    Science.gov (United States)

    Kozak, Jennifer A; Wu, Jie; Su, Xiao; Simeon, Fritz; Hatton, T Alan; Jamison, Timothy F

    2013-12-11

    A continuous method for the formation of cyclic carbonates from epoxides and carbon dioxide (CO2) is described. The catalysts used are inexpensive and effective in converting the reagents to the products in a residence time (t(R)) of 30 min. The cyclic carbonate products are obtained in good to excellent yield (51-92%). On the basis of a series of kinetics experiments, we propose a reaction mechanism involving epoxide activation by electrophilic bromine and CO2 activation by an amide.

  17. 锥台光纤的功率转换效率研究%Power conversion efficiency of tapered fiber

    Institute of Scientific and Technical Information of China (English)

    蒋瑶; 肖志刚

    2011-01-01

    锥台光纤在激光束到单模光纤以及多模光纤到单模光纤的耦合中,在一些需要质量很高光束的同时有较高功率要求的场合有广泛应用.在这些应用中,锥台光纤的功率转换效率是很重要的一个参数.介绍了锥台光纤的熔拉研磨制作方法,分析了锥台光纤的传输特性.建立了高斯近似模型,采用模场耦合理论,计算了锥台光纤的功率转换效率.在以下参数条件下对细端半径分别为(4±1)μm,(5±1)μm,(6±1)μm,(7±1)μm和(8±1)μm的锥台光纤的功率转换效率进行了实验测定,激光器输出光波长532 nm;多模光纤NA=O.11,纤芯丰径a =12.5μm;得到了与理论计算吻合的结果.%Since tapered fiber works as a connector between multi-mode fiber and single-mode fiber to improve the coupling efficiency and transmits laser beam with high power and good beam quality under single-mode conditions, the power conversion efficiency of the tapered fiber is important. A method of melting and drawing tapered fiber was introduced and the transmission characteristic of tapered fiber was discussed. A Gaussian approximation model to calculate the conversion efficiency of tapered fiber was presented based on mode field coupling theory. The simulation result was discussed and an experiment was conducted with 532 nm laser, multi-mode fiber with NA=0. 11, a=12. 5 μm and tapered fiber with NA = 0. 11, a = (4±l)μm,(5± 1)μm, (6± l)μm, (7 ± 1)μm and (8±l)μm respectively, to measure the conversion efficiency of tapered fiber. The experimental results agree with the theoretical prediction.

  18. Dual-Layer Nanostructured Flexible Thin-Film Amorphous Silicon Solar Cells with Enhanced Light Harvesting and Photoelectric Conversion Efficiency.

    Science.gov (United States)

    Lin, Yinyue; Xu, Zhen; Yu, Dongliang; Lu, Linfeng; Yin, Min; Tavakoli, Mohammad Mahdi; Chen, Xiaoyuan; Hao, Yuying; Fan, Zhiyong; Cui, Yanxia; Li, Dongdong

    2016-05-01

    Three-dimensional (3-D) structures have triggered tremendous interest for thin-film solar cells since they can dramatically reduce the material usage and incident light reflection. However, the high aspect ratio feature of some 3-D structures leads to deterioration of internal electric field and carrier collection capability, which reduces device power conversion efficiency (PCE). Here, we report high performance flexible thin-film amorphous silicon solar cells with a unique and effective light trapping scheme. In this device structure, a polymer nanopillar membrane is attached on top of a device, which benefits broadband and omnidirectional performances, and a 3-D nanostructure with shallow dent arrays underneath serves as a back reflector on flexible titanium (Ti) foil resulting in an increased optical path length by exciting hybrid optical modes. The efficient light management results in 42.7% and 41.7% remarkable improvements of short-circuit current density and overall efficiency, respectively. Meanwhile, an excellent flexibility has been achieved as PCE remains 97.6% of the initial efficiency even after 10 000 bending cycles. This unique device structure can also be duplicated for other flexible photovoltaic devices based on different active materials such as CdTe, Cu(In,Ga)Se2 (CIGS), organohalide lead perovskites, and so forth. PMID:27052357

  19. Revisiting Morrison and Osterle 1965: the efficiency of membrane-based electrokinetic energy conversion

    Science.gov (United States)

    Catalano, J.; Hamelers, H. V. M.; Bentien, A.; Biesheuvel, P. M.

    2016-08-01

    We revisit Morrison and Osterle (1965) who derived a phenomenological expression for the ‘figure-of-merit’ {β\\text{EK}} of the electrokinetic energy conversion (EKEC) of a pressure difference into electric energy (and vice versa) using charged nanotubes, nanopores or ion-exchange membranes. We show the equivalence with Morrison and Osterle of a novel expression of {β\\text{EK}} derived by Bentien et al (2013). We analyze two physical models for ionic and solvent flow which directly relate {β\\text{EK}} to nanopore characteristics such as pore size and wall charge density. For the uniform potential model, we derive an analytical expression as a function of pore size, viscosity, ion diffusion coefficients and membrane charge density, and compare results with the full space-charge model by Osterle and co-workers as a function of pore size and ion diffusion coefficient. We present a novel expression for {β\\text{EK}} for salt solutions with ions with unequal diffusion coefficients (mobilities) and show that to increase {β\\text{EK}} the counterion mobility must be low and the coion mobility high.

  20. Efficient conversion of phenylpyruvic acid to phenyllactic acid by using whole cells of Bacillus coagulans SDM.

    Directory of Open Access Journals (Sweden)

    Zhaojuan Zheng

    Full Text Available BACKGROUND: Phenyllactic acid (PLA, a novel antimicrobial compound with broad and effective antimicrobial activity against both bacteria and fungi, can be produced by many microorganisms, especially lactic acid bacteria. However, the concentration and productivity of PLA have been low in previous studies. The enzymes responsible for conversion of phenylpyruvic acid (PPA into PLA are equivocal. METHODOLOGY/PRINCIPAL FINDINGS: A novel thermophilic strain, Bacillus coagulans SDM, was isolated for production of PLA. When the solubility and dissolution rate of PPA were enhanced at a high temperature, whole cells of B. coagulans SDM could effectively convert PPA into PLA at a high concentration (37.3 g l(-1 and high productivity (2.3 g l(-1 h(-1 under optimal conditions. Enzyme activity staining and kinetic studies identified NAD-dependent lactate dehydrogenases as the key enzymes that reduced PPA to PLA. CONCLUSIONS/SIGNIFICANCE: Taking advantage of the thermophilic character of B. coagulans SDM, a high yield and productivity of PLA were obtained. The enzymes involved in PLA production were identified and characterized, which makes possible the rational design and construction of microorganisms suitable for PLA production with metabolic engineering.

  1. Lipase cocktail for efficient conversion of oils containing phospholipids to biodiesel.

    Science.gov (United States)

    Amoah, Jerome; Ho, Shih-Hsin; Hama, Shinji; Yoshida, Ayumi; Nakanishi, Akihito; Hasunuma, Tomohisa; Ogino, Chiaki; Kondo, Akihiko

    2016-07-01

    The presence of phospholipid has been a challenge in liquid enzymatic biodiesel production. Among six lipases that were screened, lipase AY had the highest hydrolysis activity and a competitive transesterification activity. However, it yielded only 21.1% FAME from oil containing phospholipids. By replacing portions of these lipases with a more robust bioFAME lipase, CalT, the combination of lipase AY-CalT gave the highest FAME yield with the least amounts of free fatty acids and partial glycerides. A higher methanol addition rate reduced FAME yields for lipase DF-CalT and A10D-CalT combinations while that of lipase AY-CalT combination improved. Optimizing the methanol addition rate for lipase AY-CalT resulted in a FAME yield of 88.1% at 2h and more than 95% at 6h. This effective use of lipases could be applied for the rapid and economic conversion of unrefined oils to biodiesel. PMID:27019125

  2. Efficient conversion of xylose to ethanol by stress-tolerant Kluyveromyces marxianus BUNL-21.

    Science.gov (United States)

    Nitiyon, Sukanya; Keo-Oudone, Chansom; Murata, Masayuki; Lertwattanasakul, Noppon; Limtong, Savitree; Kosaka, Tomoyuki; Yamada, Mamoru

    2016-01-01

    The fermentation ability of thermotolerant Kluyveromyces marxianus BUNL-21 isolated in Laos was investigated. Comparison with thermotolerant K. marxianus DMKU3-1042 as one of the most thermotolerant yeasts isolated previously revealed that the strain possesses stronger ability for conversion of xylose to ethanol, resistance to 2-deoxyglucose in the case of pentose, and tolerance to various stresses including high temperature and hydrogen peroxide. K. marxianus BUNL-21 was found to have ethanol fermentation activity from xylose that is slightly lower and much higher than that of Scheffersomyces stipitis (Pichia stipitis) at 30 °C and at higher temperatures, respectively. The lower ethanol production seems to be due to large accumulation of acetic acid. The possible mechanism of acetic acid accumulation is discussed. In addition, it was found that both K. marxianus strains produced ethanol in the presence of 10 mM hydroxymethylfurfural or furfural, at a level almost equivalent to that in their absence. Therefore, K. marxianus BUNL-21 is a highly competent yeast for high-temperature ethanol fermentation with lignocellulosic biomass. PMID:27026881

  3. Efficient control of odors and VOC emissions via activated carbon technology.

    Science.gov (United States)

    Mohamed, Farhana; Kim, James; Huang, Ruey; Nu, Huong Ton; Lorenzo, Vlad

    2014-07-01

    This research study was undertaken to enhance the efficiency and economy of carbon scrubbers in controlling odors and volatile organic compounds (VOCs) at the wastewater collection and treatment facilities of the Bureau of Sanitation, City of Los Angeles. The butane activity and hydrogen sulfide breakthrough capacity of activated carbon were assessed. Air streams were measured for odorous gases and VOCs and removal efficiency (RE) determined. Carbon towers showed average to excellent removal of odorous compounds, VOCs, and siloxanes; whereas, wet scrubbers demonstrated good removal of odorous compounds but low to negative removal of VOCs. It was observed that the relative humidity and empty bed contact time are one of the most important operating parameters of carbon towers impacting the pollutant RE. Regular monitoring of activated carbon and VOCs has resulted in useful information on carbon change-out frequency, packing recommendations, and means to improve performance of carbon towers.

  4. Multi-keV X-Ray Conversion Efficiency in Laser-Produced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Back, C A; Landen, O L; Hammer, J H; Suter, L J; Miller, M C; Davis, J; Grun, J

    2002-10-31

    X-ray sources are created at the Nova and Omega laser by irradiating a confined volume of Ar, Xe, or Kr gas. The gas is heated by forty 0.35 {micro}m wavelength, 1-ns square laser beams to produce He-like ions that radiate K-shell emission over mm-sized dimensions. The targets are designed to be ''underdense'', meaning that the initial gas density is lower than the critical density of the laser, n{sub c} {approx} 10{sup 21} cm{sup -3}. The laser energy is primarily absorbed by inverse bremsstrahlung and a supersonic heat wave efficiently ionizes the gas. Results from time-resolved and time-integrated diagnostics over a range of experimental parameters are compared. This work represents an important, new method for development of efficient, large-area, tailored multi-keV x-ray sources.

  5. Elementary Mode Analysis for the Rational Design of Efficient Succinate Conversion from Glycerol by Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zhen Chen

    2010-01-01

    Full Text Available By integrating the restriction of oxygen and redox sensing/regulatory system, elementary mode analysis was used to predict the metabolic potential of glycerol for succinate production by E. coli under either anaerobic or aerobic conditions. It was found that although the theoretical maximum succinate yields under both anaerobic and aerobic conditions are 1.0 mol/mol glycerol, the aerobic condition was considered to be more favorable for succinate production. Although increase of the oxygen concentration would reduce the succinate yield, the calculation suggests that controlling the molar fraction of oxygen to be under 0.65 mol/mol would be beneficial for increasing the succinate productivity. Based on the elementary mode analysis, the rational genetic modification strategies for efficient succinate production under aerobic and anaerobic conditions were obtained, respectively. Overexpressing the phosphoenolpyruvate carboxylase or heterogonous pyruvate carboxylase is considered to be the most efficient strategy to increase the succinate yield.

  6. Advanced Organic Vapor Cycles for Improving Thermal Conversion Efficiency in Renewable Energy Systems

    OpenAIRE

    Ho, Tony

    2012-01-01

    The Organic Flash Cycle (OFC) is proposed as a vapor power cycle that could potentially increase power generation and improve the utilization efficiency of renewable energy and waste heat recovery systems. A brief review of current advanced vapor power cycles including the Organic Rankine Cycle (ORC), the zeotropic Rankine cycle, the Kalina cycle, the transcritical cycle, and the trilateral flash cycle is presented. The premise and motivation for the OFC concept is that essentially by impro...

  7. Robust triboelectric nanogenerator based on rolling electrification and electrostatic induction at an instantaneous energy conversion efficiency of ∼ 55%.

    Science.gov (United States)

    Lin, Long; Xie, Yannan; Niu, Simiao; Wang, Sihong; Yang, Po-Kang; Wang, Zhong Lin

    2015-01-27

    In comparison to in-pane sliding friction, rolling friction not only is likely to consume less mechanical energy but also presents high robustness with minimized wearing of materials. In this work, we introduce a highly efficient approach for harvesting mechanical energy based on rolling electrification and electrostatic induction, aiming at improving the energy conversion efficiency and device durability. The rolling triboelectric nanogenerator is composed of multiple steel rods sandwiched by two fluorinated ethylene propylene (FEP) thin films. The rolling motion of the steel rods between the FEP thin films introduces triboelectric charges on both surfaces and leads to the change of potential difference between each pair of electrodes on back of the FEP layer, which drives the electrons to flow in the external load. As power generators, each pair of output terminals works independently and delivers an open-circuit voltage of 425 V, and a short-circuit current density of 5 mA/m(2). The two output terminals can also be integrated to achieve an overall power density of up to 1.6 W/m(2). The impacts of variable structural factors were investigated for optimization of the output performance, and other prototypes based on rolling balls were developed to accommodate different types of mechanical energy sources. Owing to the low frictional coefficient of the rolling motion, an instantaneous energy conversion efficiency of up to 55% was demonstrated and the high durability of the device was confirmed. This work presents a substantial advancement of the triboelectric nanogenerators toward large-scope energy harvesting and self-powered systems. PMID:25555045

  8. Conversion of biomass-derived sorbitol to glycols over carbon-materials supported Ru-based catalysts

    Science.gov (United States)

    Guo, Xingcui; Guan, Jing; Li, Bin; Wang, Xicheng; Mu, Xindong; Liu, Huizhou

    2015-11-01

    Ruthenium (Ru) supported on activated carbon (AC) and carbon nanotubes (CNTs) was carried out in the hydrogenolysis of sorbitol to ethylene glycol (EG) and 1,2-propanediol (1,2-PD) under the promotion of tungsten (WOx) species and different bases. Their catalytic activities and glycols selectivities strongly depended on the support properties and location of Ru on CNTs, owning to the altered metal-support interactions and electronic state of ruthenium. Ru located outside of the tubes showed excellent catalytic performance than those encapsulated inside the nanotubes. Additionally, the introduction of WOx into Ru/CNTs significantly improved the hydrogenolysis activities, and a complete conversion of sorbitol with up to 60.2% 1,2-PD and EG yields was obtained on RuWOx/CNTs catalyst upon addition of Ca(OH)2. Stability study showed that this catalyst was highly stable against leaching and poisoning and could be recycled several times.

  9. Design techniques for modular integrated utility systems. [energy production and conversion efficiency

    Science.gov (United States)

    Wolfer, B. M.

    1977-01-01

    Features basic to the integrated utility system, such as solid waste incineration, heat recovery and usage, and water recycling/treatment, are compared in terms of cost, fuel conservation, and efficiency to conventional utility systems in the same mean-climatic area of Washington, D. C. The larger of the two apartment complexes selected for the test showed the more favorable results in the three areas of comparison. Restrictions concerning the sole use of currently available technology are hypothetically removed to consider the introduction and possible advantages of certain advanced techniques in an integrated utility system; recommendations are made and costs are estimated for each type of system.

  10. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    OpenAIRE

    Martí, A.; De Luque, A.

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base–emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers th...

  11. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    OpenAIRE

    Martí Vega, Antonio; Luque López, Antonio

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base-emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers th...

  12. Low Emission Conversion of Fossil Fuels with Simultaneous or Consecutive Storage of Carbon Dioxide

    NARCIS (Netherlands)

    Eftekhari, A. A.

    2013-01-01

    This thesis evaluates the possibility of using underground coal gasification with a low CO2 footprint. The thesis consists of two parts. In the first part, by using the concept of exergy, a framework was constructed through which the practicality (feasibility) of an energy conversion/extraction meth

  13. Microwave energy application on carbon cathode for high efficient microbial electrosynthesis

    Science.gov (United States)

    Nie, Huarong; Cui, Mengmeng; Zhang, Tian; Lovley, Derek; Russell, Thomas

    2013-03-01

    Microbial electrosynthesis represents a promising strategy of energy storage through microbial conversion of carbon dioxide to transportation fuels or other organic commodities. One key feature for its commercialization is to enhance the cathode performance associated with microbial inoculums. A biocompatible, high surface area, multi-level porous cathode was developed from microwave pyrolysis of ferrocene on carbon felt to support the microorganism to produce acetate from carbon dioxide. The formed nanostructure flake composite on fibers increased the biofilm-cathode interfacial surface area, the interaction between the cathode surface and the microbial biofilm and the electractivity of cathode, while the macroscale porous structure of the intertwined carbon fibers provides easy microbe access. Around 743 mM cm-2 d-1 of acetate was generated by Sporomusa, which is 3.2 fold larger than the reported highest value coming from the chitosan coated carbon cloth cathode.

  14. Current matching using CdSe quantum dots to enhance the power conversion efficiency of InGaP/GaAs/Ge tandem solar cells.

    Science.gov (United States)

    Lee, Ya-Ju; Yao, Yung-Chi; Tsai, Meng-Tsan; Liu, An-Fan; Yang, Min-De; Lai, Jiun-Tsuen

    2013-11-01

    A III-V multi-junction tandem solar cell is the most efficient photovoltaic structure that offers an extremely high power conversion efficiency. Current mismatching between each subcell of the device, however, is a significant challenge that causes the experimental value of the power conversion efficiency to deviate from the theoretical value. In this work, we explore a promising strategy using CdSe quantum dots (QDs) to enhance the photocurrent of the limited subcell to match with those of the other subcells and to enhance the power conversion efficiency of InGaP/GaAs/Ge tandem solar cells. The underlying mechanism of the enhancement can be attributed to the QD's unique capacity for photon conversion that tailors the incident spectrum of solar light; the enhanced efficiency of the device is therefore strongly dependent on the QD's dimensions. As a result, by appropriately selecting and spreading 7 mg/mL of CdSe QDs with diameters of 4.2 nm upon the InGaP/GaAs/Ge solar cell, the power conversion efficiency shows an enhancement of 10.39% compared to the cell's counterpart without integrating CdSe QDs. PMID:24514936

  15. Preface for the Special Column of Carbon Materials for Energy Conversion

    Institute of Scientific and Technical Information of China (English)

    Xiulian Pan

    2012-01-01

    Carbon is one of the few elements known since ancient time.It exists as diamond and graphite in nature.Since synthetic carbon became available almost a century ago,it has been widely used in many fields and the best known applications are adsorbents and catalyst supports.Development of material science and nanotechnologies has allowed tailored design and synthesis of carbon allotropes with markedly different properties by combining the basic building blocks in different configurations.This has led to the discovery of Buckminsterfullerene or buckyball (C60),carbon nanotubes (CNTs),and graphene,and their derivatives within last 30 years highlighted by several Nobel Prize awards.Their superior properties of chemical stability,rich surface chemistry and fast electron mobility with rather well defined structure in contrast to "classical" carbon materials based on graphite and carbon black have aroused worldwide enthusiasm in many scientific and technological areas.On top of that,careful modification and decoration of these carbon allotropes with functional groups make it possible to further fine tune their properties.This has invoked significant interest in assembling them into functionalized materials for applications in energy-related processes e.g.catalytic processes,fuel cells,batteries and supercapacitors.

  16. Conversion of sand filters into activated carbon filters at the La Presa (Valencia) water works; Conversion de filtros de arena porcarbon activo en la ETAP de La Presa (Valencia)

    Energy Technology Data Exchange (ETDEWEB)

    Macian Cervera, V. J.; Monforte Monleon, L.; Ribera Orts, R.; Suris Jorda, J. I.; Klee, J. M.

    2007-07-01

    To improve the water quality at potable water treatment plant of La P esa (Valencia), the sand filters have been replaced for activated carbon filters. In the following review the results and conclusions of the direct sand filter conversion into activated carbon filters will be presented. The leads to a simple and fast solution to odour and taste removal, as well as dissolved organic matter, without investments in works at the water works. (Author)

  17. Anatase TiO(2) nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells.

    Science.gov (United States)

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO(2) nanosheets (TiO(2)-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC(4)H(9))(4) as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N(2) adsorption-desorption isotherms. The photoelectric conversion performances of TiO(2)-NSs solar cells are also compared with TiO(2) nanoparticles (TiO(2)-NPs) and commercial-grade Degussa P25 TiO(2) nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO(2)-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO(2) nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  18. Anatase TiO2 nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye-sensitized solar cells

    Science.gov (United States)

    Yu, Jiaguo; Fan, Jiajie; Lv, Kangle

    2010-10-01

    Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO2 nanosheets (TiO2-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC4H9)4 as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of TiO2-NSs solar cells are also compared with TiO2 nanoparticles (TiO2-NPs) and commercial-grade Degussa P25 TiO2 nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO2-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO2 nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

  19. Rapid and Efficient Direct Conversion of Human Adult Somatic Cells into Neural Stem Cells by HMGA2/let-7b

    Directory of Open Access Journals (Sweden)

    Kyung-Rok Yu

    2015-01-01

    Full Text Available A recent study has suggested that fibroblasts can be converted into mouse-induced neural stem cells (miNSCs through the expression of defined factors. However, successful generation of human iNSCs (hiNSCs has proven challenging to achieve. Here, using microRNA (miRNA expression profile analyses, we showed that let-7 microRNA has critical roles for the formation of PAX6/NESTIN-positive colonies from human adult fibroblasts and the proliferation and self-renewal of hiNSCs. HMGA2, a let-7-targeting gene, enables induction of hiNSCs that displayed morphological/molecular features and in vitro/in vivo differentiation potential similar to H9-derived NSCs. Interestingly, HMGA2 facilitated the efficient conversion of senescent somatic cells or blood CD34+ cells into hiNSCs through an interaction with SOX2, whereas other combinations or SOX2 alone showed a limited conversion ability. Taken together, these findings suggest that HMGA2/let-7 facilitates direct reprogramming toward hiNSCs in minimal conditions and maintains hiNSC self-renewal, providing a strategy for the clinical treatment of neurological diseases.

  20. Colloidal CuFeS2 Nanocrystals: Intermediate Fe d-Band Leads to High Photothermal Conversion Efficiency

    CERN Document Server

    Ghosh, S; Petrelli, A; Kriegel, I; Gaspari, R; Almeida, G; Bertoni, G; Cavalli, A; Scotognella, F; Pellegrino, T; Manna, L

    2016-01-01

    We describe the colloidal hot-injection synthesis of phase-pure nanocrystals (NCs) of a highly abundant mineral, chalcopyrite (CuFeS2). Absorption bands centered at around 480 and 950 nm, spanning almost the entire visible and near infrared regions, encompass their optical extinction characteristics. These peaks are ascribable to electronic transitions from the valence band (VB) to the empty intermediate band (IB), located in the fundamental gap and mainly composed of Fe 3d orbitals. Laser-irradiation (at 808 nm) of an aqueous suspension of CuFeS2 NCs exhibited significant heating, with a photothermal conversion efficiency of 49%. Such efficient heating is ascribable to the carrier relaxation within the broad IB band (owing to the indirect VB-IB gap), as corroborated by transient absorption measurements. The intense absorption and high photothermal transduction efficiency (PTE) of these NCs in the so-called biological window (650-900 nm) makes them suitable for photothermal therapy as demonstrated by tumor ce...

  1. Scalable water splitting on particulate photocatalyst sheets with a solar-to-hydrogen energy conversion efficiency exceeding 1%

    Science.gov (United States)

    Wang, Qian; Hisatomi, Takashi; Jia, Qingxin; Tokudome, Hiromasa; Zhong, Miao; Wang, Chizhong; Pan, Zhenhua; Takata, Tsuyoshi; Nakabayashi, Mamiko; Shibata, Naoya; Li, Yanbo; Sharp, Ian D.; Kudo, Akihiko; Yamada, Taro; Domen, Kazunari

    2016-06-01

    Photocatalytic water splitting using particulate semiconductors is a potentially scalable and economically feasible technology for converting solar energy into hydrogen. Z-scheme systems based on two-step photoexcitation of a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) are suited to harvesting of sunlight because semiconductors with either water reduction or oxidation activity can be applied to the water splitting reaction. However, it is challenging to achieve efficient transfer of electrons between HEP and OEP particles. Here, we present photocatalyst sheets based on La- and Rh-codoped SrTiO3 (SrTiO3:La, Rh; ref. ) and Mo-doped BiVO4 (BiVO4:Mo) powders embedded into a gold (Au) layer. Enhancement of the electron relay by annealing and suppression of undesirable reactions through surface modification allow pure water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm. The photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors.

  2. Scalable water splitting on particulate photocatalyst sheets with a solar-to-hydrogen energy conversion efficiency exceeding 1.

    Science.gov (United States)

    Wang, Qian; Hisatomi, Takashi; Jia, Qingxin; Tokudome, Hiromasa; Zhong, Miao; Wang, Chizhong; Pan, Zhenhua; Takata, Tsuyoshi; Nakabayashi, Mamiko; Shibata, Naoya; Li, Yanbo; Sharp, Ian D; Kudo, Akihiko; Yamada, Taro; Domen, Kazunari

    2016-06-01

    Photocatalytic water splitting using particulate semiconductors is a potentially scalable and economically feasible technology for converting solar energy into hydrogen. Z-scheme systems based on two-step photoexcitation of a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) are suited to harvesting of sunlight because semiconductors with either water reduction or oxidation activity can be applied to the water splitting reaction. However, it is challenging to achieve efficient transfer of electrons between HEP and OEP particles. Here, we present photocatalyst sheets based on La- and Rh-codoped SrTiO3 (SrTiO3:La, Rh; ref. ) and Mo-doped BiVO4 (BiVO4:Mo) powders embedded into a gold (Au) layer. Enhancement of the electron relay by annealing and suppression of undesirable reactions through surface modification allow pure water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm. The photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors.

  3. Characterization of deliberately nickel-doped silicon wafers and solar cells. [microstructure, electrical properties, and energy conversion efficiency

    Science.gov (United States)

    Salama, A. M.

    1980-01-01

    Microstructural and electrical evaluation tests were performed on nickel-doped p-type silicon wafers before and after solar cell fabrication. The concentration levels of nickel in silicon were 5 x 10 to the 14th power, 4 x 10 to the 15th power, and 8 x 10 to the 15th power atoms/cu cm. It was found that nickel precipitated out during the growth process in all three ingots. Clumps of precipitates, some of which exhibited star shape, were present at different depths. If the clumps are distributed at depths approximately 20 micron apart and if they are larger than 10 micron in diameter, degradation occurs in solar cell electrical properties and cell conversion efficiency. The larger the size of the precipitate clump, the greater the degradation in solar cell efficiency. A large grain boundary around the cell effective area acted as a gettering center for the precipitates and impurities and caused improvement in solar cell efficiency. Details of the evaluation test results are given.

  4. Effects of cadmium, 2,4-dichlorophenol, and pentachlorophenol on feeding, growth, and particle-size-conversion efficiency of white sucker larvae and young common shiners

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.; Ralph, K.M.

    1986-09-01

    Feeding rates, growth rates, and biomass conversion efficiencies were determined for white sucker larvae and young common shiners fed natural zooplankton during one week exposures to cadmium (suckers and shiners), 2,4-dichlorophenol (DCP) (shiners only), or pentachlorophenol (PCP) (shiners only). All three toxicants significantly reduced growth rates at sublethal concentrations. Growth rates were reduced up to 67 to 100% by DCP and cadmium, but the effect was smaller (a 25% reduction) for shiners. Feeding rates were not significantly affected by cadmium or DCP exposure, but shiners exposed to PCP had significantly increased feeding rates. All toxicants, therefore, reduced conversion efficiencies by > 50% at sublethal concentrations. Toxicants which reduce conversion efficiency have the potential for reducing the production of top predators (large piscivores) by an amount greater than the relative effect on any one trophic level (as demonstrated in laboratory experiments) because reductions in efficiency over multiple trophic levels are cumulative.

  5. Perspectives of the microbial carbon pump with special references to microbial respiration and ecological efficiency

    Directory of Open Access Journals (Sweden)

    H. Dang

    2014-01-01

    Full Text Available Although respiration consumes fixed carbon and produce CO2, it provides energy for essential biological processes of an ecosystem, including the microbial carbon pump (MCP. In MCP-driving biotransformation of labile DOC to recalcitrant DOC (RDOC, microbial respiration provides the metabolic energy for environmental organic substrate sensing, cellular enzyme syntheses and catalytic processes such as uptake, secretion, modification, fixation and storage of carbon compounds. The MCP efficiency of a heterotrophic microorganism is thus related to its energy production efficiency and hence to its respiration efficiency. Anaerobically respiring microbes usually have lower energy production efficiency and lower energy-dependent carbon transformation efficiency, and consequently lower MCP efficiency at per cell level. This effect is masked by the phenomena that anoxic environments often store more organic matter. Here we point out that organic carbon preservation and RDOC production is different in mechanisms, and anaerobically respiring ecosystems could also have lower MCP ecological efficiency. Typical cases can be found in large river estuarine ecosystems. Due to strong terrigenous input of nutrients and organic matter, estuarine ecosystems usually experience intense heterotrophic respiration processes that rapidly consume dissolved oxygen, potentially producing hypoxic and anoxic zones in the water column. The lowered availability of dissolved oxygen and the excessive supply of nutrients such as nitrate from river input prompt enhanced anaerobic respiration processes. Thus, some nutrients may be consumed by anaerobically respiring heterotrophic microorganisms, instead of being utilized by phytoplankton for carbon fixation and primary production. In this situation, the ecological functioning of the estuarine ecosystem is altered and the ecological efficiency is lowered, as less carbon is fixed and less energy is produced. Ultimately this would have

  6. Perspectives of the microbial carbon pump with special references to microbial respiration and ecological efficiency

    Science.gov (United States)

    Dang, H.; Jiao, N.

    2014-01-01

    Although respiration consumes fixed carbon and produce CO2, it provides energy for essential biological processes of an ecosystem, including the microbial carbon pump (MCP). In MCP-driving biotransformation of labile DOC to recalcitrant DOC (RDOC), microbial respiration provides the metabolic energy for environmental organic substrate sensing, cellular enzyme syntheses and catalytic processes such as uptake, secretion, modification, fixation and storage of carbon compounds. The MCP efficiency of a heterotrophic microorganism is thus related to its energy production efficiency and hence to its respiration efficiency. Anaerobically respiring microbes usually have lower energy production efficiency and lower energy-dependent carbon transformation efficiency, and consequently lower MCP efficiency at per cell level. This effect is masked by the phenomena that anoxic environments often store more organic matter. Here we point out that organic carbon preservation and RDOC production is different in mechanisms, and anaerobically respiring ecosystems could also have lower MCP ecological efficiency. Typical cases can be found in large river estuarine ecosystems. Due to strong terrigenous input of nutrients and organic matter, estuarine ecosystems usually experience intense heterotrophic respiration processes that rapidly consume dissolved oxygen, potentially producing hypoxic and anoxic zones in the water column. The lowered availability of dissolved oxygen and the excessive supply of nutrients such as nitrate from river input prompt enhanced anaerobic respiration processes. Thus, some nutrients may be consumed by anaerobically respiring heterotrophic microorganisms, instead of being utilized by phytoplankton for carbon fixation and primary production. In this situation, the ecological functioning of the estuarine ecosystem is altered and the ecological efficiency is lowered, as less carbon is fixed and less energy is produced. Ultimately this would have negatively impacts

  7. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

    Science.gov (United States)

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-06-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation.

  8. Tunneling-injection in vertical quasi-2D heterojunctions enabled efficient and adjustable optoelectronic conversion.

    Science.gov (United States)

    Tan, Wei-Chun; Chiang, Chia-Wei; Hofmann, Mario; Chen, Yang-Fang

    2016-01-01

    The advent of 2D materials integration has enabled novel heterojunctions where carrier transport proceeds thrsough different ultrathin layers. We here demonstrate the potential of such heterojunctions on a graphene/dielectric/semiconductor vertical stack that combines several enabling features for optoelectronic devices. Efficient and stable light emission was achieved through carrier tunneling from the graphene injector into prominent states of a luminescent material. Graphene's unique properties enable fine control of the band alignment in the heterojunction. This advantage was used to produce vertical tunneling-injection light-emitting transistors (VtiLET) where gating allows adjustment of the light emission intensity independent of applied bias. This device was shown to simultaneously act as a light detecting transistor with a linear and gate tunable sensitivity. The presented development of an electronically controllable multifunctional light emitter, light detector and transistor open up a new route for future optoelectronics. PMID:27507171

  9. AREA EFFICIENT FRACTIONAL SAMPLE RATE CONVERSION ARCHITECTURE FOR SOFTWARE DEFINED RADIOS

    Directory of Open Access Journals (Sweden)

    Latha Sahukar

    2014-09-01

    Full Text Available The modern software defined radios (SDRs use complex signal processing algorithms to realize efficient wireless communication schemes. Several such algorithms require a specific symbol to sample ratio to be maintained. In this context the fractional rate converter (FRC becomes a crucial block in the receiver part of SDR. The paper presents an area optimized dynamic FRC block, for low power SDR applications. The limitations of conventional cascaded interpolator and decimator architecture for FRC are also presented. Extending the SINC function interpolation based architecture; towards high area optimization and providing run time configuration with time register are presented. The area and speed analysis are carried with Xilinx FPGA synthesis tools. Only 15% area occupancy with maximum clock speed of 133 MHz are reported on Spartan-6 Lx45 Field Programmable Gate Array (FPGA.

  10. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling.

    Science.gov (United States)

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-01-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation. PMID:27324578

  11. Tunneling-injection in vertical quasi-2D heterojunctions enabled efficient and adjustable optoelectronic conversion

    Science.gov (United States)

    Tan, Wei-Chun; Chiang, Chia-Wei; Hofmann, Mario; Chen, Yang-Fang

    2016-08-01

    The advent of 2D materials integration has enabled novel heterojunctions where carrier transport proceeds thrsough different ultrathin layers. We here demonstrate the potential of such heterojunctions on a graphene/dielectric/semiconductor vertical stack that combines several enabling features for optoelectronic devices. Efficient and stable light emission was achieved through carrier tunneling from the graphene injector into prominent states of a luminescent material. Graphene’s unique properties enable fine control of the band alignment in the heterojunction. This advantage was used to produce vertical tunneling-injection light-emitting transistors (VtiLET) where gating allows adjustment of the light emission intensity independent of applied bias. This device was shown to simultaneously act as a light detecting transistor with a linear and gate tunable sensitivity. The presented development of an electronically controllable multifunctional light emitter, light detector and transistor open up a new route for future optoelectronics.

  12. Three-Phase PWM Power Conversion--The Route to Ultra High Power Density and Efficiency

    Institute of Scientific and Technical Information of China (English)

    J W Kolar; J Minib(o)ck; T Nussbaumer

    2005-01-01

    A review of three-phase PWM converter topologies which do show a low complexity/high reliability and high efficiency and power density and are therefore of main interest for a future industrial application is presented.A three-switch/level Boost-type PWM rectifier (VIENNA Rectifier),a Buck+Boost-type PWM rectifier with wide output voltage range and the AC/AC Sparse Matrix Converter concept are discussed in detail and topics to be treated in the course of further research are identified. Finally,it is shown how the aspects being relevant for the realization of highly compact converter systems could be integrated into education in the field.

  13. Efficient conversion of surface-plasmon-like modes to spatial radiated modes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jun Jun; Zhang, Hao Chi; Zhang, Qian; Cui, Tie Jun, E-mail: tjcui@seu.edu.cn [State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096 (China)

    2015-01-12

    We propose a spoof surface plasmon polariton (SPP) emitter which is composed of ultrathin corrugated metallic strips, exhibiting the directional radiation property. The spoof SPP emitter provides a way to quickly convert the SPP mode to a radiated mode. By controlling phase modulations produced by the phase-gradient metasurface on the ultrathin metallic strips, we demonstrate theoretically and experimentally that spoof SPP waves are converted into spatial propagating waves with high efficiency, which are further radiated with flexible beam steering. The proposed method sets up a link between SPP waves and radiation waves in a highly controllable way, which would possibly open an avenue in designing new kinds of microwave and optical elements in engineering.

  14. Outstanding efficiency in energy conversion for electric motors constructed by nanocrystalline soft magnetic alloy "NANOMET®" cores

    Science.gov (United States)

    Nishiyama, N.; Tanimoto, K.; Makino, A.

    2016-05-01

    Recently updated nanocrystalline soft magnetic Fe-Co-Si-B-P-Cu alloys "NANOMET®" exhibit high saturation magnetic flux density (Bs > 1.8 T), low coercivity (Hc motors or transformers for electrical appliances are now under developing by industry-academia collaboration. In particular, it is found that a brushless DC motor using NANOMET® core exhibited remarkable improvement in energy consumption. The prototype motor with an outer core diameter of 70 mm and a core thickness of 50 mm was constructed using laminated nano-crystallized NANOMET® ribbons. Core-loss for the constructed motor was improved from 1.4 W to 0.4 W only by replacing the non-oriented Si-steel core with NANOMET® one. The overall motor efficiency is evaluated to be 3% improvement. In this work, the relation between processing and resulting magnetic properties will be presented. In addition, feasibility for commercialization will also be discussed.

  15. Effects of feed intake and genetics on tissue nitrogen-15 enrichment and feed conversion efficiency in sheep.

    Science.gov (United States)

    Cheng, L; Logan, C M; Dewhurst, R J; Hodge, S; Zhou, H; Edwards, G R

    2015-12-01

    This study investigated the effects of sheep genetics and feed intake on nitrogen isotopic fractionation (ΔN) and feed conversion efficiency (FCE; live weight gain/DMI), using a 2 × 2 factorial design, with 2 levels of genetic merit for growth (high vs. low) and 2 levels of feed intake (110 vs. 170% of ME for maintenance [MEm]). No effect of genetic merit was detected for live weight gain ( = 0.64), FCE ( = 0.46), plasma urea nitrogen ( = 0.52), plasma glucose ( = 0.78), and ΔN of wool ( = 0.45), blood ( = 0.09), and plasma ( = 0.51). Sheep receiving 170% of MEm had 175% higher live weight gain ( feed. There was a higher blood, plasma, and wool ∆N for the low feed intake group than the high feed intake group ( biomarker of FCE in sheep, despite there being no effects of genetic treatment on FCE and ∆N. PMID:26641195

  16. Stearic-acid/carbon-nanotube composites with tailored shape-stabilized phase transitions and light–heat conversion for thermal energy storage

    International Nuclear Information System (INIS)

    Highlights: • A facile preparation of shape-stabilized composite PCMs for thermal energy storage. • The composite PCMs present tunable phase change temperatures and enthalpy. • Sunlight-driven phase change for photothermal conversion and storage. - Abstract: The development of functional materials with both light–heat conversion and thermal energy storage properties is of crucial importance for efficient utilization of sunlight to meet the growing demand for sustainable energy. In this work, the shape-stabilized phase change composites were designed and prepared by integration of stearic acid (SA) and acid-treated carbon nanotubes (a-CNTs). The a-CNTs not only acted as a flexible matrix but also endowed the composites high light–heat conversion ability. The reversible phase transitions shifted from high temperatures (Tm = 74 °C, Tf = 57 °C) of pure SA to near room temperature (Tm = ∼30 °C, Tf = ∼22 °C) of SA/a-CNTs composites, probably resulting from the strong interface confinement effect. The phase change enthalpy of the SA/a-CNTs composite could also be tailored by changing the mass ratio of SA and a-CNTs. The composites containing SA of 54.2 wt.%, 67.8 wt.% and 79.5 wt.% presented the melting enthalpy of 76.3 J/g, 98.8 J/g and 111.8 J/g, respectively. Moreover, the phase transition of SA/a-CNTs composite could be driven by sunlight for the energy storage/release. Therefore, this research provides a new platform for improving solar utilization, and understanding the phase transition behaviors of organic PCMs in dimensionally confined environments as well

  17. Fabrication of voids-involved SnO2@C nanofibers electrodes with highly reversible Sn/SnO2 conversion and much enhanced coulombic efficiency for lithium-ion batteries

    Science.gov (United States)

    Xie, Wenhe; Gu, Lili; Xia, Fangyuan; Liu, Boli; Hou, Xiaoyi; Wang, Qi; Liu, Dequan; He, Deyan

    2016-09-01

    Despite their potential application in lithium-ion battery electrodes, one apparent disadvantage for SnO2-based materials is that the electrodes suffer low coulombic efficiency especially for the initial cycle, which originates from the irreversible conversion of SnO2 to Sn, the formation of solid electrolyte interphase and the other possible side reactions. Here we design a novel nanofiber structure in which SnO2 nanoparticles are well separated and confined by inner porous carbon framework and then hooped by outer carbon shell. The resultant SnO2/voids@C nanofibers electrode displays not only a high reversible capacity of 986 mAh g-1 at 200 mA g-1 after 200 cycles, but also a high initial coulombic efficiency of 73.5%. It has been shown that such a rational design can efficiently reduce the side reactions and promote the reversible conversion of Sn to SnO2 for both half and full cells.

  18. IMPROVING THE EFFICIENCY OF CARBON DIOXIDE SUPPLY ON UREA SYNTHESIS

    OpenAIRE

    Лавренченко, Г. К.; Копытин, А. В.; Афанасьев, С. В.; Рощенко, О. С.

    2011-01-01

    Aggregates of urea synthesis are reconstructed with the purpose decrease in specific expenses and increase their productivity. Supply of additional quantities of carbon dioxide and ammonia is necessary to increase production volumes of urea. In most cases there is a problem with the supply of СО2, as the equipment for its compression is not any necessary reserves. Installation for supply of carbon dioxide using a pump is considered. For liquefaction of CO2 at low pressure the cold of the liqu...

  19. Carbon sequestration from waste via conversion to charcoal : equipment for a small scale operation

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, S.C. [Cenovus Energy Inc., Calgary, AB (Canada); Struyk, A. [AST Technical Services, Calgary, AB (Canada); Gilbert, D. [GTEC Consulting, Calgary, AB (Canada)

    2010-07-01

    Carbon capture and sequestration (CCS) is not very cost effective in oilsand operations. For that reason, this study examined the feasibility of using charcoal sequestration (CS) as an alternative carbon offset method to CCS. The economics of the charcoal approach depends on 2 factors, notably the cost of the feed biomass and the cost of processing. The first factor was addressed in this study by using municipal waste as feedstock which is available free of charge. Since the cost of processing depends on the apparatus and the scale of operation, a robust kiln was designed to convert waste at remote industrial camp sites to charcoal. In charcoal sequestration, carbon contained in a portion of naturally produced biomass is preserved in solid form by converting it to charcoal, thus preventing it from entering into atmosphere as carbon dioxide. The paper showed that the newly designed equipment can contribute to a reduction in waste disposal costs and that the study can serve as a demonstration and data collection project for waste-to-charcoal projects for carbon sequestration. These demo projects can also help evaluate various aspects of this novel method of sequestration, and enhance public awareness on the subject. In view of the growing per capita waste worldwide, use of municipal waste as feedstock for charcoal sequestration can be a significant measure of carbon offset at global scale. 10 refs., 7 figs.

  20. Aboveground carbon stocks in oil palm plantations and the threshold for carbon-neutral vegetation conversion on mineral soils

    NARCIS (Netherlands)

    Khasanah, N.; Noordwijk, van M.; Ningsih, H.

    2015-01-01

    The carbon (C) footprint of palm oil production is needed to judge emissions from potential biofuel use. Relevance includes wider sustainable palm oil debates. Within life cycle analysis, aboveground C debt is incurred if the vegetation replaced had a higher C stock than oil palm plantations. Our st

  1. Point Climat no. 27 'Unlocking private investments in energy efficiency through carbon finance'

    International Nuclear Information System (INIS)

    Among the publications of CDC Climat Research, 'Climate Briefs' presents, in a few pages, hot topics in climate change policy. This issue addresses the following points: According to the latest IEA World Energy Outlook, energy efficiency is a 'key option' in transition to a low-carbon economy. A decade of experience with the CDM and JI demonstrates that carbon finance can be used as an effective tool to unlock private investments in energy efficiency. Capital investments in offset projects may significantly exceed the expected carbon revenues resulting in an average weighted leverage ratio of 4:1 and 9:1 for the CDM and JI respectively, which is comparable to other international financial instruments. So far carbon finance has been used mostly for large-scale industrial energy efficiency projects in advanced developing countries and economies in transition, although it is increasingly suited to tap into scattered household energy efficiency projects

  2. Theranostic carbon dots derived from garlic with efficient anti-oxidative effects towards macrophages

    DEFF Research Database (Denmark)

    Yang, Chuanxu; Ogaki, Ryosuke; Hansen, Line;

    2015-01-01

    Luminescent garlic carbon dots with superior photostability are synthesized via microwave assisted heating. The garlic dots are biocompatible, have low toxicity and can be used as benign theranostic nanoparticles for bioimaging with efficient anti-oxidative effects towards macrophages....

  3. Linking Transformational Materials and Processing for an Energy-Efficient and Low-Carbon Economy, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, Warren H. [Minerals, Metals, and Materials Society (TMS), Warrendale, PA (United States); Brindle, Ross [Nexight Group, LLC, Silver Spring, MD (United States); James, Mallory [Energetics Inc., Columbia, MD (United States); Justiniano, Mauricio [Energetics Inc., Columbia, MD (United States); Sabouni, Ridah [Energetics Inc., Columbia, MD (United States); Seader, Melanie [Energetics Inc., Columbia, MD (United States); Ruch, Jennifer [Energetics Inc., Columbia, MD (United States); Andres, Howard [Energetics Inc., Columbia, MD (United States); Zafar, Muhammad [Energetics Inc., Columbia, MD (United States)

    2010-06-01

    The Energy Materials Blue Ribbon Panel, representing experts from industry, academia, and government, identifies new materials and processing breakthroughs that could lead to transformational advances in energy efficiency, energy security, and carbon reduction.

  4. Low Emission Conversion of Fossil Fuels with Simultaneous or Consecutive Storage of Carbon Dioxide

    OpenAIRE

    Eftekhari, A.A.

    2013-01-01

    This thesis evaluates the possibility of using underground coal gasification with a low CO2 footprint. The thesis consists of two parts. In the first part, by using the concept of exergy, a framework was constructed through which the practicality (feasibility) of an energy conversion/extraction method can be systematically evaluated. This framework, based on exergy analysis and cumulative degree of perfection, is described by analyzing a low emission underground coal gasification (UCG) proces...

  5. Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid

    OpenAIRE

    Xuezheng Liang; Shao-Qin Lv; Lin-Mei Rong; Sheng-Xian Zhao; Chunqing Li; Baowei Hu; Chenze Qi

    2010-01-01

    The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols ...

  6. Efficient near-infrared up-conversion photoluminescence in carbon nanotubes

    OpenAIRE

    Akizuki, Naoto; Aota, Shun; Mouri, Shinichiro; Matsuda, Kazunari; Miyauchi, Yuhei

    2015-01-01

    カーボンナノチューブの新しい光機能「アップコンバージョン発光」を発見 -生体組織内部の近赤外光イメージング応用に期待-. 京都大学プレスリリース. 2015-11-17.

  7. Efficient multi-mode to single-mode conversion in a 61 port photonic lantern

    Science.gov (United States)

    Noordegraaf, D.; Skovgaard, P. M. W.; Maack, M. D.; Bland-Hawthorn, J.; Haynes, R.; Lægsgaard, J.

    2010-02-01

    We demonstrate the fabrication of a multi-mode (MM) to 61 port single-mode (SM) splitter or "Photonic Lantern". Low port count Photonic Lanterns were first described by Leon-Saval et al. (2005). These are based on a photonic crystal fiber type design, with air-holes defining the multi-mode fiber (MMF) cladding. Our fabricated Photonic Lanterns are solid all-glass versions, with the MMF defined by a low-index tube surrounding the single-mode fibers (SMFs). We show experimentally that these devices can be used to achieve efficient and reversible coupling between a MMF and 61 SMFs, when perfectly matched launch conditions into the MMF are ensured. The total coupling loss from a 100 μm core diameter MM section to the ensemble of 61 SMFs and back to another 100 μm core MM section is measured to be as low as 0.76 dB. This demonstrates the feasibility of using the Photonic Lanterns within the field of astrophotonics for coupling MM star-light to an ensemble of SM fibers in order to perform fiber Bragg grating based spectral filtering.

  8. Efficient multi-mode to single-mode conversion in a 61 port photonic lantern

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Skovgaard, Peter M. W.; Dybendahl Maack, Martin;

    2010-01-01

    We demonstrate the fabrication of a multi-mode (MM) to 61 port single-mode (SM) splitter or "Photonic Lantern". Low port count Photonic Lanterns were first described by Leon-Saval et al. (2005). These are based on a photonic crystal fiber type design, with air-holes defining the multi-mode fiber...... (MMF) cladding. Our fabricated Photonic Lanterns are solid all-glass versions, with the MMF defined by a low-index tube surrounding the single-mode fibers (SMFs). We show experimentally that these devices can be used to achieve efficient and reversible coupling between a MMF and 61 SMFs, when perfectly...... matched launch conditions into the MMF are ensured. The total coupling loss from a 100 µm core diameter MM section to the ensemble of 61 SMFs and back to another 100 µm core MM section is measured to be as low as 0.76 dB. This demonstrates the feasibility of using the Photonic Lanterns within the field...

  9. Evaluation of the Wave Energy Conversion Efficiency in Various Coastal Environments

    Directory of Open Access Journals (Sweden)

    Eugen Rusu

    2014-06-01

    Full Text Available The main objective of the present work was to assess and compare the wave power resources in various offshore and nearshore areas. From this perspective, three different groups of coastal environments were considered: the western Iberian nearshore, islands and an enclosed environment with sea waves, respectively. Some of the most representative existent wave converters were evaluated in the analysis and a second objective was to compare their performances at the considered locations, and in this way to determine which is better suited for potential commercial exploitation. In order to estimate the electric power production expected in a certain location, the bivariate distributions of the occurrences corresponding to the sea states, defined by the significant wave height and the energy period, were constructed in each coastal area. The wave data were provided by hindcast studies performed with numerical wave models or based on measurements. The transformation efficiency of the wave energy into electricity is evaluated via the load factor and also through the capture width, defined as the ratio between the electric power estimated to be produced by each specific wave energy converters (WEC and the expected wave power corresponding to the location considered. Finally, by evaluating these two different indicators, comparisons of the performances of three WEC types (Aqua Buoy, Pelamis and Wave Dragon in the three different groups of coastal environments considered have been also carried out. The work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments.

  10. Polyacrylonitrile/carbon nanotube composite fibers: Reinforcement efficiency and carbonization studies

    Science.gov (United States)

    Chae, Han Gi

    Polyacrylonitrile (PAN)/carbon nanotube (CNT) composite fibers were made using various processing methods such as conventional solution spinning, gel spinning, and bi-component gel spinning. The detailed characterization exhibited that the smaller and longer CNT will reinforce polymer matrix mostly in tensile strength and modulus, respectively. Gel spinning combined with CNT also showed the promising potential of PAN/CNT composite fiber as precursor fiber of the next generation carbon fiber. High resolution transmission electron microscopy showed the highly ordered PAN crystal layer on the CNT, which attributed to the enhanced physical properties. The subsequent carbonization study revealed that carbonized PAN/CNT fibers have at least 50% higher tensile strength and modulus as compared to those of carbonized PAN fibers. Electrical conductivity of CNT containing carbon fiber was also 50% higher than that of carbonized PAN fiber. In order to have carbon fiber with high tensile strength, the smaller diameter precursor fiber is preferable. Bi-component gel spinning produced 1-2 mum precursor fiber, resulting in ˜1 mum carbon fiber. The tensile strength of the carbonized bi-component fiber (islands fibers) is as high as 6 GPa with tensile modulus of ˜500 GPa. Further processing optimization may lead to the next generation carbon fiber.

  11. Energy Efficiency and Carbon Management in Mineral Processing Plants

    OpenAIRE

    Miti, Wilson

    2014-01-01

    Copper processing plants involved in smelting, electro-refining and electro-winning are heat-intensive undertakings that provide extensive challenges for attainment of high energy efficiency. Literature has shown that most of these plants, especially smelters, operate at low overall energy efficiency due to the seemingly complex energy scenario where heat and electricity as forms of energy are treated distinctively from each other. Many copper processing plants have not yet explored both avai...

  12. Catalytic conversion of alcohols having at least three carbon atoms to hydrocarbon blendstock

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.

    2015-11-13

    A method for producing a hydrocarbon blendstock, the method comprising contacting at least one saturated acyclic alcohol having at least three and up to ten carbon atoms with a metal-loaded zeolite catalyst at a temperature of at least 100°C and up to 550°C, wherein the metal is a positively-charged metal ion, and the metal-loaded zeolite catalyst is catalytically active for converting the alcohol to the hydrocarbon blendstock, wherein the method directly produces a hydrocarbon blendstock having less than 1 vol % ethylene and at least 35 vol % of hydrocarbon compounds containing at least eight carbon atoms.

  13. Water Boiling inside Carbon Nanotubes: Towards Efficient Drug Release

    OpenAIRE

    Chaban, Vitaly V.; Prezhdo, Oleg V.

    2012-01-01

    We show using molecular dynamics simulation that spatial confinement of water inside carbon nanotubes (CNT) substantially increases its boiling temperature and that a small temperature growth above the boiling point dramatically raises the inside pressure. Capillary theory successfully predicts the boiling point elevation down to 2 nm, below which large deviations between the theory and atomistic simulation take place. Water behaves qualitatively different inside narrow CNTs, exhibiting trans...

  14. Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing

    Directory of Open Access Journals (Sweden)

    Andrej Petrov

    2016-05-01

    CONCLUSION: Multifunctional fractional carbon dioxide laser used in treatment of patients with acne and pigmentation from acne, as well as in the treatment of scars from different backgrounds, is an effective and safe method that causes statistically significant better effect of the treatment, greater patients’ satisfaction, minimal side effects and statistically better response to the therapy, according to assessments by the patient and the therapist.

  15. Competitive distortions, carbon emissions efficiencies or the green ultimatum?

    OpenAIRE

    Truxal, S.

    2008-01-01

    Discusses whether the US air transport industry will be obliged to reduce carbon emissions if the liberalisation of transatlantic air transport is to continue under the European Union-United States Open Skies Air Transport Agreement 2007. Considers the EU proposal to require airlines which fly to or from Europe to join the EU emissions trading scheme or a comparable national scheme under Directive 2003/87 art.25. Compares the arguments for environmental taxes or emissions trading schemes, and...

  16. Roll-coating fabrication of flexible large area small molecule solar cells with power conversion efficiency exceeding 1%

    DEFF Research Database (Denmark)

    Liu, Wenqing; Liu, Shiyong; Zawacka, Natalia Klaudia;

    2014-01-01

    All solution-processed flexible large area small molecule bulk heterojunction solar cells were fabricated via roll-coating technology. Our devices were produced from slot-die coating on a lab-scale mini roll-coater under ambient conditions without the use of spin-coating or vacuum evaporation...... methods. Four diketopyrrolopyrrole based small molecules (SMs 1-4) were utilized as electron donors with (6,6)phenyl- C61-butyric acid methyl ester as an acceptor and their photovoltaic performances based on roll-coated devices were investigated. The best power conversion efficiency (PCE) of 1.......01%, combined with an open circuit voltage of 0.73 V, a short-circuit current density of 3.13 mA cm (2) and a fill factor of 44% were obtained for the device with SM1, which was the first example reported for efficient roll-coating fabrication of flexible large area small molecule solar cells with PCE exceeding...

  17. Unraveling the Fundamental Mechanisms of Solvent-Additive-Induced Optimization of Power Conversion Efficiencies in Organic Photovoltaic Devices.

    Science.gov (United States)

    Herath, Nuradhika; Das, Sanjib; Zhu, Jiahua; Kumar, Rajeev; Chen, Jihua; Xiao, Kai; Gu, Gong; Browning, James F; Sumpter, Bobby G; Ivanov, Ilia N; Lauter, Valeria

    2016-08-10

    The realization of controllable morphologies of bulk heterojunctions (BHJ) in organic photovoltaics (OPVs) is one of the key factors enabling high-efficiency devices. We provide new insights into the fundamental mechanisms essential for the optimization of power conversion efficiencies (PCEs) with additive processing to PBDTTT-CF:PC71BM system. We have studied the underlying mechanisms by monitoring the 3D nanostructural modifications in BHJs and correlated the modifications with the optical analysis and theoretical modeling of charge transport. Our results demonstrate profound effects of diiodooctane (DIO) on morphology and charge transport in the active layers. For small amounts of DIO (3 vol %), DIO facilitates a loosely packed mixed morphology with large clusters of PC71BM, leading to deterioration in PCE. Theoretical modeling of charge transport reveals that DIO increases the mobility of electrons and holes (the charge carriers) by affecting the energetic disorder and electric field dependence of the mobility. Our findings show the implications of phase separation and carrier transport pathways to achieve optimal device performances.

  18. Improved power conversion efficiency of dye-sensitized solar cells using side chain liquid crystal polymer embedded in polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Woosum [Department of Chemistry Education, and Department of Frontier Materials Chemistry, and Institute for Plastic Information and Energy Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Lee, Jae Wook, E-mail: jlee@donga.ac.kr [Department of Chemistry, Dong-A University, Busan 604-714 (Korea, Republic of); Gal, Yeong-Soon [Polymer Chemistry Lab, College of General Education, Kyungil University, Hayang 712-701 (Korea, Republic of); Kim, Mi-Ra, E-mail: mrkim2@pusan.ac.kr [Department of Polymer Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Jin, Sung Ho, E-mail: shjin@pusan.ac.kr [Department of Chemistry Education, and Department of Frontier Materials Chemistry, and Institute for Plastic Information and Energy Materials, Pusan National University, Busan 609-735 (Korea, Republic of)

    2014-02-14

    Side chain liquid crystal polymer (SCLCP) embedded in poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based polymer electrolytes (PVdF-co-HFP:side chain liquid crystal polymer (SCLCP)) was prepared for dye-sensitized solar cell (DSSC) application. The polymer electrolytes contained tetrabutylammonium iodide (TBAI), iodine (I{sub 2}), and 8 wt% PVdF-co-HFP in acetonitrile. DSSCs comprised of PVdF-co-HFP:SCLCP-based polymer electrolytes displayed enhanced redox couple reduction and reduced charge recombination in comparison to those of the conventional PVdF-co-HFP-based polymer electrolyte. The significantly increased short-circuit current density (J{sub sc}, 10.75 mA cm{sup −2}) of the DSSCs with PVdF-co-HFP:SCLCP-based polymer electrolytes afforded a high power conversion efficiency (PCE) of 5.32% and a fill factor (FF) of 0.64 under standard light intensity of 100 mW cm{sup −2} irradiation of AM 1.5 sunlight. - Highlights: • We developed the liquid crystal polymer embedded on polymer electrolyte for DSSCs. • We fabricated the highly efficient DSSCs using polymer electrolyte. • The best PCE achieved for P1 is 5.32% using polymer electrolyte.

  19. Conceptual Design of Solar-micro Hydro Power Plant to Increase Conversion Efficiency for Supporting Remote Tribal Community of Bangladesh

    Directory of Open Access Journals (Sweden)

    Anmona Shabnam Pranti

    2014-11-01

    Full Text Available Bangladesh is endowed with people along with limited primary energy sources and low electrification rate. Most of the hilly areas are out of the coverage of national grid where tribal people, a significant part of the country, are dwelling. The economic development of the whole country depends upon their advancement which is related to the electrification rate. Available micro hydro potential in hilly region could be a solution for this crisis if modified design is used. This paper deals with a new design of water power potential conversion efficiency increment of a micro hydro power plant to 95% from about 50% by using solar power for heating the water. In this proposed hybrid design, a parabolic reflector is considered to be used after comparative solar intensity analysis on different micro hydro power sites in Bangladesh to increase the velocity as well as the flow rate through penstock by heating the water to increase power production and efficiency. The main purpose of this concept is to supply electricity to more people, especially, remote tribal community by available renewable energy sources for economic development.

  20. Enhancement of the power conversion efficiency for organic photovoltaic cells with a Liq/bathocuproine electron transport bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ke; Kim, Dae Hun; Lee, Se Han; Kim, Tae Whan, E-mail: twk@hanyang.ac.kr

    2013-11-29

    Organic photovoltaic (OPV) cells based on a poly(3-hexylthiophene) (P3HT):fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) active layer with a bathocuproine (BCP)/8-hydroxyquinoline lithium (Liq) electron transport layer were fabricated to enhance their power conversion efficiency (PCE). Absorbance spectra showed that the absorbance intensity of the spectra for the P3HT:PCBM active layer with a Liq layer in the wavelength between 500 and 600 nm was enhanced due to the damage of the active layer. The PCE of the fabricated OPV cells with a Liq/BCP layer was significantly enhanced by up to 4.29% in comparison with that of OPV cells with a BCP or a Liq layer. - Highlights: • Organic photovoltaic cell with a bathocuproine (BCP)/8-hydroxyquinoline lithium (Liq) layer. • The BCP layer prevented the performance deterioration. • The efficiency of the photovoltaic cell with a BCP/Liq layer was enhanced.

  1. Unraveling the Fundamental Mechanisms of Solvent-Additive-Induced Optimization of Power Conversion Efficiencies in Organic Photovoltaic Devices.

    Science.gov (United States)

    Herath, Nuradhika; Das, Sanjib; Zhu, Jiahua; Kumar, Rajeev; Chen, Jihua; Xiao, Kai; Gu, Gong; Browning, James F; Sumpter, Bobby G; Ivanov, Ilia N; Lauter, Valeria

    2016-08-10

    The realization of controllable morphologies of bulk heterojunctions (BHJ) in organic photovoltaics (OPVs) is one of the key factors enabling high-efficiency devices. We provide new insights into the fundamental mechanisms essential for the optimization of power conversion efficiencies (PCEs) with additive processing to PBDTTT-CF:PC71BM system. We have studied the underlying mechanisms by monitoring the 3D nanostructural modifications in BHJs and correlated the modifications with the optical analysis and theoretical modeling of charge transport. Our results demonstrate profound effects of diiodooctane (DIO) on morphology and charge transport in the active layers. For small amounts of DIO (3 vol %), DIO facilitates a loosely packed mixed morphology with large clusters of PC71BM, leading to deterioration in PCE. Theoretical modeling of charge transport reveals that DIO increases the mobility of electrons and holes (the charge carriers) by affecting the energetic disorder and electric field dependence of the mobility. Our findings show the implications of phase separation and carrier transport pathways to achieve optimal device performances. PMID:27403964

  2. Influence of metal grid spacing on the conversion efficiency of concentration solar cell at different illumination levels

    International Nuclear Information System (INIS)

    Highlights: • Grid shadowing ratio dominated the performance of SC at low concentration levels. • Grid shadowing ratio and resistance need optimal balance at high concentration levels. • Pioneering study (theoretical and experimental): the effect of metallic grid patterns on SC. - Abstract: The design of front metal grid spacing of linear grid pattern for III–V multi-junction concentrated solar cells is a critical issue when high density photocurrent is induced under concentrated sunlight and a poor grid spacing results in resistive losses. In the present work we have performed outdoor experiment and investigated both theoretically and experimentally the effect of ten different metal grid spacing on the electrical performance of high efficiency GaInP/GaInAs/Ge concentrated solar cells under various concentrating level of sunlight. The shadowing ratio of metal grids was adjusted from 3.07% to 6.66%. We have observed that the variation of experimentally obtained variation of power conversion efficiency data with grid spacing is consistent with the variation of theoretical estimation of total power loss with grid spacing. Moreover, the total power loss was dominated by grid shadowing effect at lower concentration levels; while at higher concentration levels the lowest total power loss condition was found when a compromise occurred mainly between grid shadowing effect and resistance of metal lines

  3. Designing carbon nanotube membranes for efficient water desalination.

    Science.gov (United States)

    Corry, Ben

    2008-02-01

    The transport of water and ions through membranes formed from carbon nanotubes ranging in diameter from 6 to 11 A is studied using molecular dynamics simulations under hydrostatic pressure and equilibrium conditions. Membranes incorporating carbon nanotubes are found to be promising candidates for water desalination using reverse osmosis, and the size and uniformity of tubes that is required to achieve a desired salt rejection is determined. By calculating the potential of mean force for ion and water translocation, we show that ions face a large energy barrier and will not pass through the narrower tubes studied ((5,5) and (6,6) "armchair" type tubes) but can pass through the wider (7,7) and (8,8) nanotubes. Water, however, faces no such impediment due to the formation of stable hydrogen bonds and crosses all of the tubes studied at very large rates. By measuring this conduction rate under a hydrostatic pressure difference, we show that membranes incorporating carbon nanotubes can, in principle, achieve a high degree of desalination at flow rates far in excess of existing membranes. PMID:18163610

  4. Calcium carbonate electronic-insulating layers improve the charge collection efficiency of tin oxide photoelectrodes in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    In dye-sensitized solar cells (DSSCs), a surface passivation layer has been employed on the tin oxide (SnO2) photoanodes to enhance the charge collection efficiency, and thus the power conversion efficiency. Herein, we demonstrate that the electronic-insulating layering of calcium carbonate (CaCO3) can improve the charge collection efficiency in dye-sensitized solar cells designed with photoanodes. In order to evaluate the effectiveness of CaCO3 layering, both layered and pristine SnO2 photoanodes are characterized with regard to their structures, morphologies, and photo-electrochemical measurements. The SnO2-6L CaCO3 photoanode has demonstrated as high as 3.5% power conversion efficiency; 3.5-fold greater than that of the pristine SnO2 photoanode. The enhancement in the power conversion efficiency is corroborated with the number of the dye molecules, the passivation of surface states, a negative shift in the conduction band position, and the reduced electron recombination rate of photoelectrons following the coating of the CaCO3 surface layer

  5. Efficiency of inhibitor for biocorrosion influenced by consortium sulfate reducing bacteria on carbon steel

    Science.gov (United States)

    Mahat, Nur Akma; Othman, Norinsan Kamil; Sahrani, Fathul Karim

    2015-09-01

    The inhibition efficiency of benzalkonium chloride (BKC) in controlling biocorrosion on the carbon steel surfaces has been investigated. The carbon steel coupons were incubated in the presence of consortium SRB (C-SRB) with and without BKC for the difference medium concentration. The corrosion rate and inhibition efficiency have been evaluated by a weight loss method. The morphology of biofilm C-SRB on the steel surfaces were characterized with variable pressure scanning electron microscopy (VPSEM). The results revealed that BKC exhibits a low corrosion rate, minimizing the cell growth and biofilm development on the carbon steel surfaces.

  6. Efficiency of inhibitor for biocorrosion influenced by consortium sulfate reducing bacteria on carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Mahat, Nur Akma; Othman, Norinsan Kamil [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Sahrani, Fathul Karim [School of Environment and Natural Resources Science, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2015-09-25

    The inhibition efficiency of benzalkonium chloride (BKC) in controlling biocorrosion on the carbon steel surfaces has been investigated. The carbon steel coupons were incubated in the presence of consortium SRB (C-SRB) with and without BKC for the difference medium concentration. The corrosion rate and inhibition efficiency have been evaluated by a weight loss method. The morphology of biofilm C-SRB on the steel surfaces were characterized with variable pressure scanning electron microscopy (VPSEM). The results revealed that BKC exhibits a low corrosion rate, minimizing the cell growth and biofilm development on the carbon steel surfaces.

  7. Genetic Polymorphisms of Mc4R and IGF2 Gene Association with Feed Conversion Efficiency Traits in Beef Cattle

    Directory of Open Access Journals (Sweden)

    Xin-hua Du§, Cui Chen§, Zheng-rong Yuan, Li-min Zhang, Xiao-jie Chen, Yan-hui Wang, Xue Gao, Lu-pei Zhang, Hui-jiang Gao, Jun-ya Li and Shang-zhong Xu*

    2013-11-01

    Full Text Available Melanocortin-4 receptor (MC4R gene is part of the central melanocortin pathway located in the hypothalamus, an area of the brain in which appetite is regulated. Insulin-like growth factor 2 (IGF2 gene plays a role in muscle growth, myoblast proliferation and differentiation. Thus, they are candidate genes for feed conversion efficiency (FCE. The study was to investigate the effects of variants in cattle MC4R and IGF2 gene on FCE traits including residual feed intake (RFI, feed conversion ratio (FCR and average daily gain (ADG. We screened single nucleotide polymorphisms (SNPs of the two genes in 118 Simmental bulls by DNA-pool sequencing and genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS analysis. C1069G locus of MC4R and four SNPs (C2209T, G18587C, A22950T and G26920T of IGF2 were identified in the population. The χ2 test showed that only MC4R-C1069G, IGF2-C2209T and IGF2-G18587C loci fitted with Hardy-Weinberg equilibrium (P>0.05. General linear model (GLM was used to analyze differences between genotypes. The results showed that only IGF2-G18587C locus has a significant effect on ADG (P0.05. CC and GG genotypes were the dominant genotypes; individual with CC or GG genotype had a larger ADG than GC (P<0.05.

  8. Heat pumps; Synergy of high efficiency and low carbon electricity

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Akio

    2010-09-15

    Heat pump is attracting wide attention for its high efficiency to utilize inexhaustible and renewable ambient heat in the environment. With its rapid innovation and efficiency improvement, this technology has a huge potential to reduce CO2 emissions by replacing currently widespread fossil fuel combustion systems to meet various heat demands from the residential, commercial and industrial sectors. Barriers to deployment such as low public awareness and a relatively long pay-back period do exist, so it is strongly recommended that each country implement policies to promote heat pumps as a renewable energy option and an effective method to combat global warming.

  9. Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid

    Directory of Open Access Journals (Sweden)

    Xuezheng Liang

    2010-08-01

    Full Text Available The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and β-keto esters make this novel carbon based acid one of the best choices for the reaction.

  10. Removal efficiency of radioactive methyl iodide on TEDA-impregnated activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Garcia, C.M.; Gonzalez, J.F.; Roman, S. [Extremadura Univ., Badajoz (Spain). Dept. de Fisica Aplicada

    2011-02-15

    Activated carbons were prepared by different series of carbon dioxide and steam activation from walnut shells for their optimal use as radioactive methyl iodide adsorbents in Nuclear Plants. The knowledge of the most favourable textural characteristics of the activated carbons was possible by the previous study of the commercial activated carbon currently used for this purpose. In order to increase their methyl iodide affinity, the effect of triethylenediamine impregnation was studied at 5 and 10 wt.%. The results obtained indicated that in both cases the adsorption efficiency is markedly improved by the addition of impregnant, which allows the adsorbate uptake to occur not only by physical adsorption, via non-specific interactions (as in non-impregnated carbons) but also by the specific interaction of triethylenediamine with radioactive methyl iodide. Methyl iodide retention efficiencies up to 98.1% were achieved. (author)

  11. Copper indium disulfide nanocrystals supported on carbonized chicken eggshell membranes as efficient counter electrodes for dye-sensitized solar cells

    Science.gov (United States)

    Wang, Lidan; He, Jianxin; Zhou, Mengjuan; Zhao, Shuyuan; Wang, Qian; Ding, Bin

    2016-05-01

    A domestic waste, chicken eggshell membrane (ESM), is used as a raw material to fabricate carbonized ESM loaded with chalcopyrite CuInS2 nanocrystals (denoted CESM-CuInS2) by a simple liquid impregnation and carbonization method. The CESM-CuInS2 composite possesses a natural three-dimensional macroporous network structure in which numerous CuInS2 nanocrystals with a size of about 25 nm are inlaid in carbon submicron fibers that form a microporous network. The CESM-CuInS2 composite is used as the counter electrode in a dye-sensitized solar cell (DSSC) and its photoelectric performance is tested. The DSSC with a CESM-CuInS2 counter electrode exhibits a short-circuit current density of 12.48 mA cm-2, open-circuit voltage of 0.78 V and power conversion efficiency of 5.8%; better than the corresponding values for a DSSC with a CESM counter electrode, and comparable to that of a reference DSSC with a platinum counter electrode. The favorable photoelectric performance of the CESM-CuInS2 counter electrode is attributed to its hierarchical structure, which provides a large specific surface area and numerous catalytically active sites to facilitate the oxidation of the electrolyte. This new composite material has many advantages, such as low cost and simple preparation, compared with Pt and pure CuInS2 counter electrodes.

  12. Conversion of UF6 to UO2: A quasi-optimization of the ammonium uranyl carbonate process

    International Nuclear Information System (INIS)

    The ammonium uranyl carbonate (AUC) wet conversion process, one of the most important routes for preparation of uranium dioxide from UF6, was intensively investigated for process improvement and product identification. Both process variables and unit equipment were concerned. The target of this task was to prepare high quality UO2 ceramic powder and pellets. From the test results of UO2 pelletizing and sintering, the operation conditions were selected for process optimization. The criteria used in optimization condition determination were the reproducibility of the AUC product and the compressibility, the reactivity, as well as the sinterability of UO2 powder. Experimental results showed that UO2 pellets with sintered density higher than 98% TD were achieved. A set of quasi-optimum conditions for this process was also proposed. (orig.)

  13. Relationship between initial efficiency and structure parameters of carbon anode material for Li-ion battery

    Institute of Scientific and Technical Information of China (English)

    SHEN Jian-bin; TANG You-gen; LIANG Yi-zeng; TAN Xin-xin

    2008-01-01

    The initial efficiency is a very important criterion for carbon anode material of Li-ion battery. The relationship between initial efficiency and structure parameters of carbon anode material of Li-ion battery was investigated by an artificial intelligence approach called Random Forests using D10, D50, D90, BET specific surface area and TP density as inputs, initial efficiency as output.The results give good classification performance with 91% accuracy. The variable importance analysis results show the impact of 5 variables on the initial efficiency descends in the order of D90, TP density, BET specific surface area, D50 and D10; smaller D90 and larger TP density have positive impact on initial efficiency. The contribution of BET specific surface area on classification is only 18.74%, which indicates the shortcoming of BET specific surface area as a widely used parameter for initial efficiency evaluation.

  14. Assessment of the Soil Organic Carbon Sink in a Project for the Conversion of Farmland to Forestland: A Case Study in Zichang County, Shaanxi, China

    OpenAIRE

    Mu, Lan; Liang, Yinli; Han, Ruilian

    2014-01-01

    The conversion of farmland to forestland not only changes the ecological environment but also enriches the soil with organic matter and affects the global carbon cycle. This paper reviews the influence of land use changes on the soil organic carbon sink to determine whether the Chinese “Grain-for-Green” (conversion of farmland to forestland) project increased the rate of SOC content during its implementation between 1999 and 2010 in the hilly and gully areas of the Loess Plateau in north-cent...

  15. Transformation of Nickelalactones to Methyl Acrylate: On the Way to a Catalytic Conversion of Carbon Dioxide

    KAUST Repository

    Lee, S. Y. Tina

    2011-08-26

    Mu-nick: The methyl iodide-mediated ring opening of nickelalactones, which can be formed by oxidative coupling of carbon dioxide and ethylene at Ni 0 complexes, induces β-H elimination, producing methyl acrylate in yields of up to 56 %. This reaction is found to be very sensitive to the ligands coordinated to the central nickel atom. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Techniques for the conversion to carbon dioxide of oxygen from dissolved sulfate in thermal waters

    Science.gov (United States)

    Nehring, N.L.; Bowen, P.A.; Truesdell, A.H.

    1977-01-01

    The fractionation of oxygen isotopes between dissolved sulfate ions and water provides a useful geothermometer for geothermal waters. The oxygen isotope composition of dissolved sulfate may also be used to indicate the source of the sulfate and processes of formation. The methods described here for separation, purification and reduction of sulfate to prepare carbon dioxide for mass spectrometric analysis are modifications of methods by Rafter (1967), Mizutani (1971), Sakai and Krouse (1971), and Mizutani and Rafter (1969). ?? 1976.

  17. Soil carbon sensitivity to temperature and carbon use efficiency compared across microbial-ecosystem models of varying complexity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianwei [University of Oklahoma; Wang, Gangsheng [ORNL; Allison, Steven D. [University of California, Irvine; Mayes, Melanie [ORNL; Luo, Yiqi [University of Oklahoma

    2014-01-01

    Global ecosystem models may require microbial components to accurately predict feedbacks between climate warming and soil decomposition, but it is unclear what parameters and levels of complexity are ideal for scaling up to the globe. Here we conducted a model comparison using a conventional model with first-order decay and three microbial models of increasing complexity that simulate short- to long-term soil carbon dynamics. We focused on soil carbon responses to microbial carbon use efficiency (CUE) and temperature. Three scenarios were implemented in all models: constant CUE (held at 0.31), varied CUE ( 0.016 C 1), and 50 % acclimated CUE ( 0.008 C 1). Whereas the conventional model always showed soil carbon losses with increasing temperature, the microbial models each predicted a temperature threshold above which warming led to soil carbon gain. The location of this threshold depended on CUE scenario, with higher temperature thresholds under the acclimated and constant scenarios. This result suggests that the temperature sensitivity of CUE and the structure of the soil carbon model together regulate the long-term soil carbon response to warming. Equilibrium soil carbon stocks predicted by the microbial models were much less sensitive to changing inputs compared to the conventional model. Although many soil carbon dynamics were similar across microbial models, the most complex model showed less pronounced oscillations. Thus, adding model complexity (i.e. including enzyme pools) could improve the mechanistic representation of soil carbon dynamics during the transient phase in certain ecosystems. This study suggests that model structure and CUE parameterization should be carefully evaluated when scaling up microbial models to ecosystems and the globe.

  18. Catalytic conversion of biomass-derived feedstocks into olefins and aromatics with ZSM-5: the hydrogen to carbon effective ratio

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huiyan; Cheng, Yu-Ting; Vispute, Tushar; Xiao, R; Huber, George W.

    2011-01-01

    Catalytic conversion of ten biomass-derived feedstocks, i.e.glucose, sorbitol, glycerol, tetrahydrofuran, methanol and different hydrogenated bio-oil fractions, with different hydrogen to carbon effective (H/C{sub eff}) ratios was conducted in a gas-phase flow fixed-bed reactor with a ZSM-5 catalyst. The aromatic + olefin yield increases and the coke yield decreases with increasing H/C{sub eff} ratio of the feed. There is an inflection point at a H/C{sub eff} ratio = 1.2, where the aromatic + olefin yield does not increase as rapidly as it does prior to this point. The ratio of olefins to aromatics also increases with increasing H/C{sub eff} ratio. CO and CO₂ yields go through a maximum with increasing H/C{sub eff} ratio. The deactivation rate of the catalyst decreases significantly with increasing H/C{sub eff} ratio. Coke was formed from both homogeneous and heterogeneous reactions. Thermogravimetric analysis (TGA) for the ten feedstocks showed that the formation of coke from homogeneous reactions decreases with increasing H/C{sub eff} ratio. Feedstocks with a H/C{sub eff} ratio less than 0.15 produce large amounts of undesired coke (more than 12 wt%) from homogeneous decomposition reactions. This paper shows that the conversion of biomass-derived feedstocks into aromatics and olefins using zeolite catalysts can be explained by the H/C{sub eff} ratio of the feed.

  19. The ecosystem carbon accumulation after conversion of grasslands to pine plantations in subtropical red soil of South China

    International Nuclear Information System (INIS)

    Since 1980s, afforestation in China has led to the establishment of over 0.53 x 108 ha of new plantation forests. While this leads to rapid accumulation of carbon (C) in vegetation, the effects of afforestation on soil C are poorly understood. In this study, a new version of the Atmosphere-Vegetation Interaction Model (AVIM2) was used to examine how changes in plant C inputs following afforestation might lead to changes in soil C at one of the Chinaflux sites and to estimate the effect of afforestation on ex-grassland. The potential total C accumulation of tree plantation was also predicted. The model was calibrated by net ecosystem exchange (NEE), ecosystem respiration (RE) and gross primary production (GPP) based on eddy-covariance measurements. The simulated vegetation C and soil C stocks were compared with the filed observations. The simulates indicate that after 22 yr of conversion of grassland to needle leaf forests (Pinus massoniana and Pinus elliottii), the net carbon accumulation in tree ecosystem was 1.96 times more than that in grassland. The soil C in the initial 7 yr of planting decreased at a rate of 0.1871 kg C/m2/yr, and after that it increased at a rate of 0.090 kg C/m2/yr. The C accumulation in the studied plantation ecosystem is estimated to be 76-81% of that value in equilibrium state (the net ecosystem productivity approaches to zero). Sensitivity analyses show that conversion from grassland to plantation caused an initial (7 or 8 yr) periods of decrease in soil C stocks in wider red soil area of southern China. The soil C stocks were reduced between 19.2 and 20.4% in the initial decreasing period. After 7 or 8 yr C loss, the increased in soil C stocks was predicted to be between 0.073 and 0.074 kg C/m2/yr

  20. Utilization of spent activated carbon to enhance the combustion efficiency of organic sludge derived fuel.

    Science.gov (United States)

    Chen, Wei-Sheng; Lin, Chang-Wen; Chang, Fang-Chih; Lee, Wen-Jhy; Wu, Jhong-Lin

    2012-06-01

    This study examines the heating value and combustion efficiency of organic sludge derived fuel, spent activated carbon derived fuel, and derived fuel from a mixture of organic sludge and spent activated carbon. Spent activated carbon was sampled from an air pollution control device of an incinerator and characterized by XRD, XRF, TG/DTA, and SEM. The spent activated carbon was washed with deionized water and solvent (1N sulfuric acid) and then processed by the organic sludge derived fuel manufacturing process. After washing, the salt (chloride) and sulfide content could be reduced to 99% and 97%, respectively; in addition the carbon content and heating value were increased. Different ratios of spent activated carbon have been applied to the organic sludge derived fuel to reduce the NO(x) emission of the combustion.