WorldWideScience

Sample records for autonomous solar hydrogen

  1. Solar Hydrogen Reaching Maturity

    Directory of Open Access Journals (Sweden)

    Rongé Jan

    2015-09-01

    Full Text Available Increasingly vast research efforts are devoted to the development of materials and processes for solar hydrogen production by light-driven dissociation of water into oxygen and hydrogen. Storage of solar energy in chemical bonds resolves the issues associated with the intermittent nature of sunlight, by decoupling energy generation and consumption. This paper investigates recent advances and prospects in solar hydrogen processes that are reaching market readiness. Future energy scenarios involving solar hydrogen are proposed and a case is made for systems producing hydrogen from water vapor present in air, supported by advanced modeling.

  2. Autonomous solar refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Bougard, J.; Vokaert, D. (Faculte Polytechnique de Mons, Universite Libre de Bruxelles (Belgium))

    1982-11-01

    A compression refrigerator, fed by a flat solar pannel and composed of two thermal machines, working on a Rankine-Hirn cycle, is described. Mechanical energy is transferred by a double effect free-piston which is at the same time engine, pump, compressor and electric generator for auxiliaries. Freon R12 or R114 is used as the working fluid. Performances of a prototype are given. Investment for a classical unit, fed by a photovoltaic pannel would be more than twice.

  3. Hydrogen production from solar energy

    Science.gov (United States)

    Eisenstadt, M. M.; Cox, K. E.

    1975-01-01

    Three alternatives for hydrogen production from solar energy have been analyzed on both efficiency and economic grounds. The analysis shows that the alternative using solar energy followed by thermochemical decomposition of water to produce hydrogen is the optimum one. The other schemes considered were the direct conversion of solar energy to electricity by silicon cells and water electrolysis, and the use of solar energy to power a vapor cycle followed by electrical generation and electrolysis. The capital cost of hydrogen via the thermochemical alternative was estimated at $575/kW of hydrogen output or $3.15/million Btu. Although this cost appears high when compared with hydrogen from other primary energy sources or from fossil fuel, environmental and social costs which favor solar energy may prove this scheme feasible in the future.

  4. Future hybrid systems: solar and hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States); Broussard, K. [National Renewable Energy Lab., Golden, CO (United States)]|[NREL MURA Intern from Southern Univ., Baton Rouge, LA (United States)

    2003-07-01

    Future solar and hydrogen hybrid systems are discussed in terms of the evolving hydrogen economy. The focus is on distributed hydrogen, relying on the same distributed-energy strengths of solar-photovoltaic electricity in the built environment. Solar-hydrogen residences, as well as solar parks, are presented. Landarea issues are evaluated, and the economics and potential of these approaches are examined in terms of roadmap predictions on PV and hydrogen pathways. (orig.)

  5. Solar hydrogen for urban trucks

    Energy Technology Data Exchange (ETDEWEB)

    Provenzano, J.: Scott, P.B.; Zweig, R. [Clean Air Now, Northridge, CA (United States)

    1997-12-31

    The Clean Air Now (CAN) Solar Hydrogen Project, located at Xerox Corp., El Segundo, California, includes solar photovoltaic powered hydrogen generation, compression, storage and end use. Three modified Ford Ranger trucks use the hydrogen fuel. The stand-alone electrolyzer and hydrogen dispensing system are solely powered by a photovoltaic array. A variable frequency DC-AC converter steps up the voltage to drive the 15 horsepower compressor motor. On site storage is available for up to 14,000 standard cubic feet (SCF) of solar hydrogen, and up to 80,000 SCF of commercial hydrogen. The project is 3 miles from Los Angeles International airport. The engine conversions are bored to 2.9 liter displacement and are supercharged. Performance is similar to that of the Ranger gasoline powered truck. Fuel is stored in carbon composite tanks (just behind the driver`s cab) at pressures up to 3600 psi. Truck range is 144 miles, given 3600 psi of hydrogen. The engine operates in lean burn mode, with nil CO and HC emissions. NO{sub x} emissions vary with load and rpm in the range from 10 to 100 ppm, yielding total emissions at a small fraction of the ULEV standard. Two trucks have been converted for the Xerox fleet, and one for the City of West Hollywood. A public outreach program, done in conjunction with the local public schools and the Department of Energy, introduces the local public to the advantages of hydrogen fuel technologies. The Clean Air Now program demonstrates that hydrogen powered fleet development is an appropriate, safe, and effective strategy for improvement of urban air quality, energy security and avoidance of global warming impact. Continued technology development and cost reduction promises to make such implementation market competitive.

  6. Solar Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Koval, C. [Univ. of Colorado, Boulder (United States); Sutin, N. [Brookhaven National Lab., Upton, NY (United States); Turner, J. [National Renewable Energy Lab., Golden, CO (United States)

    1996-09-01

    This panel addressed different methods for the photoassisted dissociation of water into its component parts, hydrogen and oxygen. Systems considered include PV-electrolysis, photoelectrochemical cells, and transition-metal based microheterogeneous and homogeneous systems. While none of the systems for water splitting appear economically viable at the present time, the panel identified areas of basic research that could increase the overall efficiency and decrease the costs. Common to all the areas considered was the underlying belief that the water-to-hydrogen half reaction is reasonably well characterized, while the four-electron oxidation of water-to-oxygen is less well understood and represents a significant energy loss. For electrolysis, research in electrocatalysis to reduce overvoltage losses was identified as a key area for increased efficiency. Non-noble metal catalysts and less expensive components would reduce capital costs. While potentially offering higher efficiencies and lower costs, photoelectrochemical-based direct conversion systems undergo corrosion reactions and often have poor energetics for the water reaction. Research is needed to understand the factors that control the interfacial energetics and the photoinduced corrosion. Multi-photon devices were identified as promising systems for high efficiency conversion.

  7. Autonomous solar air conditioner. 100 percent solar powered; Solar autarke Klimatisierung. Mit 100% Sonnenenergie

    Energy Technology Data Exchange (ETDEWEB)

    Hindenburg, C. [Fraunhofer ISE, Freiburg (Germany)

    2004-11-01

    Autonomous solar cooling is an interesting option in all cases where storage of chilled products brings about large inherent thermal (cold) storage potential, e.g. wine production. There are also applications in air conditioning of buildings in which autonomous solar cooling systems are technically feasible and economically interesting. (orig.) [German] Generell sind alle Faelle von Prozesskuehlung, in denen durch die Lagerung von gekuehlten Produkten prozessinhaerent grosse thermische (Kaelte-)Speicher vorhanden sind, fuer die solar autarke Kuehlung interessant, beispielsweise die Weinherstellung. Es gibt aber auch Anwendungsfaelle im Bereich der Gebaeudeklimatisierung, bei denen eine solar autarke Kuehlung technisch machbar und zugleich oekonomisch darstellbar ist. (orig.)

  8. Revisiting the solar hydrogen alternative

    Energy Technology Data Exchange (ETDEWEB)

    Tomkiewicz, M. [Brooklyn College of CUNY, NY (United States)

    1996-09-01

    Research aimed at the development of technology to advance the solar-hydrogen alternative is per definition mission oriented. The priority that society puts on such research rise and fall with the priorities that we associate with the mission. The mission that we associate with the hydrogen economy is to provide a technological option for an indefinitely sustainable energy and material economies in which society is in equilibrium with its environment. In this paper we try to examine some global aspects of the hydrogen alternative and recommend formulation of a {open_quotes}rational{close_quotes} tax and regulatory system that is based on efforts needed to restore the ecological balance. Such a system, once entered into the price structure of the alternative energy schemes, will be used as a standard to compare energy systems that in turn will serve as a base for prioritization of publicly supported research and development.

  9. Prospects of solar thermal hydrogen production processes

    Energy Technology Data Exchange (ETDEWEB)

    Pregger, Thomas; Krewitt, Wolfram [German Aerospace Center (DLR), Institute of Technical Thermodynamics, Department of Systems Analysis and Technology Assessment, Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany); Graf, Daniela; Sattler, Christian; Roeb, Martin; Moeller, Stephan [German Aerospace Center (DLR), Institute of Technical Thermodynamics, Department of Solar Research, Linder Hoehe, D-51147 Cologne (Germany)

    2009-05-15

    This article provides a critical discussion of prospects of solar thermal hydrogen production in terms of technological and economic potentials and their possible role for a future hydrogen supply. The study focuses on solar driven steam methane reforming, thermochemical cycles, high temperature water electrolysis and solar methane cracking. Development status and technological challenges of the processes and objectives of ongoing research are described. Estimated hydrogen production costs are shown in comparison to other options. A summary of current discussions and today's scenarios of future use of hydrogen as an energy carrier and a brief overview on the development status of end-use technologies characterise uncertainties whether hydrogen could emerge as important energy carrier until 2050. Another focus is on industrial hydrogen demand in areas with high direct solar radiation which may be the main driver for the further development of solar thermal hydrogen production processes in the coming decades. (author)

  10. Solar based hydrogen production systems

    CERN Document Server

    Dincer, Ibrahim

    2013-01-01

    This book provides a comprehensive analysis of various solar based hydrogen production systems. The book covers first-law (energy based) and second-law (exergy based) efficiencies and provides a comprehensive understanding of their implications. It will help minimize the widespread misuse of efficiencies among students and researchers in energy field by using an intuitive and unified approach for defining efficiencies. The book gives a clear understanding of the sustainability and environmental impact analysis of the above systems. The book will be particularly useful for a clear understanding

  11. The solar-hydrogen economy: an analysis

    Science.gov (United States)

    Reynolds, Warren D.

    2007-09-01

    The 20th Century was the age of the Petroleum Economy while the 21st Century is certainly the age of the Solar-Hydrogen Economy. The global Solar-Hydrogen Economy that is now emerging follows a different logic. Under this new economic paradigm, new machines and methods are once again being developed while companies are restructuring. The Petroleum Economy will be briefly explored in relation to oil consumption, Hubbert's curve, and oil reserves with emphasis on the "oil crash". Concerns and criticisms about the Hydrogen Economy will be addressed by debunking some of the "hydrogen myths". There are three major driving factors for the establishment of the Solar-Hydrogen Economy, i.e. the environment, the economy with the coming "oil crash", and national security. The New Energy decentralization pathway has developed many progressive features, e.g., reducing the dependence on oil, reducing the air pollution and CO II. The technical and economic aspects of the various Solar-Hydrogen energy options and combinations will be analyzed. A proposed 24-hour/day 200 MWe solar-hydrogen power plant for the U.S. with selected energy options will be discussed. There are fast emerging Solar Hydrogen energy infrastructures in the U.S., Europe, Japan and China. Some of the major infrastructure projects in the transportation and energy sectors will be discussed. The current and projected growth in the Solar-Hydrogen Economy through 2045 will be given.

  12. Solar hydrogen production: renewable hydrogen production by dry fuel reforming

    Science.gov (United States)

    Bakos, Jamie; Miyamoto, Henry K.

    2006-09-01

    SHEC LABS - Solar Hydrogen Energy Corporation constructed a pilot-plant to demonstrate a Dry Fuel Reforming (DFR) system that is heated primarily by sunlight focusing-mirrors. The pilot-plant consists of: 1) a solar mirror array and solar concentrator and shutter system; and 2) two thermo-catalytic reactors to convert Methane, Carbon Dioxide, and Water into Hydrogen. Results from the pilot study show that solar Hydrogen generation is feasible and cost-competitive with traditional Hydrogen production. More than 95% of Hydrogen commercially produced today is by the Steam Methane Reformation (SMR) of natural gas, a process that liberates Carbon Dioxide to the atmosphere. The SMR process provides a net energy loss of 30 to 35% when converting from Methane to Hydrogen. Solar Hydrogen production provides a 14% net energy gain when converting Methane into Hydrogen since the energy used to drive the process is from the sun. The environmental benefits of generating Hydrogen using renewable energy include significant greenhouse gas and criteria air contaminant reductions.

  13. Solar Thermochemical Hydrogen Production Plant Design

    OpenAIRE

    Littlefield, Jesse

    2012-01-01

    A plant was designed that uses a solar sulfur-ammonia thermochemical water-splitting cycle for the production of hydrogen. Hydrogen is useful as a fuel for stationary and mobile fuel cells. The chemical process simulator Aspen Plus® was used to model the plant and conduct simulations. The process utilizes the electrolytic oxidation of aqueous ammonium sulfite in the hydrogen production half cycle and the thermal decomposition of molten potassium pyrosulfate and gaseous sulfur trioxide in t...

  14. Solar driven technologies for hydrogen production

    Directory of Open Access Journals (Sweden)

    Medojević Milovan M.

    2016-01-01

    Full Text Available Bearing in mind that the production of hydrogen based on renewable energy sources, without doubt, is an important aspect to be taken into account when considering the potential of this gas, where as particularly interesting technologies stand out the ones which are based on the use of solar energy to produce hydrogen. The goal of this paper provides basic technological trajectories, with the possibility of combining, for solar driven hydrogen production, such as: electrochemical, photochemical and thermochemical process. Furthermore, the paper presents an analysis of those technologies from a technical as well as economic point of view. In addition, the paper aims to draw attention to the fact that the generation of hydrogen using renewable energy should be imposed as a logical and proper way to store solar energy in the form of chemical energy.

  15. Solar-hydrogen generation and solar concentration (Conference Presentation)

    NARCIS (Netherlands)

    Chinello, Enrico; Modestino, Miquel A.; Schüttauf, Jan-Willem; Lambelet, David; Delfino, Antonio; Domine, Didier; Faes, Antonin; Despeisse, Matthieu; Bailat, Julien; Psaltis, Demetri; Fernandez Rivas, David; Ballif, Christophe; Moser, Christophe; Sulima, Oleg V.; Conibeer, Gavin

    2016-01-01

    We successfully demonstrated and reported the highest solar-to-hydrogen efficiency with crystalline silicon cells and Earth-abundant electrocatalysts under unconcentrated solar radiation. The combination of hetero-junction silicon cells and a 3D printed Platinum/Iridium-Oxide electrolyzer has been p

  16. Control design for an autonomous wind based hydrogen production system

    Energy Technology Data Exchange (ETDEWEB)

    Valenciaga, F.; Evangelista, C.A. [CONICET, Laboratorio de Electronica Industrial Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata, CC.91, C.P. 1900, La Plata (Argentina)

    2010-06-15

    This paper presents a complete control scheme to efficiently manage the operation of an autonomous wind based hydrogen production system. This system comprises a wind energy generation module based on a multipolar permanent magnet synchronous generator, a lead-acid battery bank as short term energy storage and an alkaline von Hoerner electrolyzer. The control is developed in two hierarchical levels. The higher control level or supervisor control determines the general operation strategy for the whole system according to the wind conditions and the state of charge of the battery bank. On the other hand, the lower control level includes the individual controllers that regulate the respective module operation assuming the set-points determined by the supervisor control. These last controllers are approached using second-order super-twisting sliding mode techniques. The performance of the closed-loop system is assessed through representative computer simulations. (author)

  17. Power supply of autonomous systems using solar modules

    Science.gov (United States)

    Yurchenko, A. V.; Zotov, L. G.; Mekhtiev, A. D.; Yugai, V. V.; Tatkeeva, G. G.

    2015-04-01

    The article shows the methods of constructing autonomous decentralized energy systems from solar modules. It shows the operation of up DC inverter. It demonstrates the effectiveness of DC inverters with varying structure. The system has high efficiency and low level of conductive impulse noise and at the same time the system is practically feasible. Electrical processes have been analyzed to determine the characteristics of operating modes of the main circuit elements. Recommendations on using the converters have been given.

  18. Design and realization of an autonomous solar system

    Science.gov (United States)

    Gaga, A.; Diouri, O.; Es-sbai, N.; Errahimi, F.

    2017-03-01

    The aim of this work is the design and realization of an autonomous solar system, with MPPT control, a regulator charge/discharge of batteries, an H-bridge multi-level inverter with acquisition system and supervising based on a microcontroller. The proposed approach is based on developing a software platform in the LabVIEW environment which gives the system a flexible structure for controlling, monitoring and supervising the whole system in real time while providing power maximization and best quality of energy conversion from DC to AC power. The reliability of the proposed solar system is validated by the simulation results on PowerSim and experimental results achieved with a solar panel, a Lead acid battery, solar regulator and an H-bridge cascaded topology of single-phase inverter.

  19. Screening analysis of solar thermochemical hydrogen concepts.

    Energy Technology Data Exchange (ETDEWEB)

    Diver, Richard B., Jr.; Kolb, Gregory J.

    2008-03-01

    A screening analysis was performed to identify concentrating solar power (CSP) concepts that produce hydrogen with the highest efficiency. Several CSP concepts were identified that have the potential to be much more efficient than today's low-temperature electrolysis technology. They combine a central receiver or dish with either a thermochemical cycle or high-temperature electrolyzer that operate at temperatures >600 C. The solar-to-hydrogen efficiencies of the best central receiver concepts exceed 20%, significantly better than the 14% value predicted for low-temperature electrolysis.

  20. Solar hydrogen: the Great Sahara project

    Energy Technology Data Exchange (ETDEWEB)

    Eljrushi, G.S. (High Industrial Inst., Misurata (Libyan Arab Jamahiriya)); Zubia, J.N. (Secretariat of Light Industry, Misurata (Libyan Arab Jamahiriya))

    1994-03-01

    This paper discusses a proposal for an international solar hydrogen project to be installed in North Africa, near the town of Ghadames in the middle of the desert, to exploit the enormous Sahara solar power resource. It suggests some practical steps to implement this project in three successive stages. The financing of the project is discussed, and the relevant local activities have been outlined. It also discusses the forming of a task force from interested parties to take initiatives and to present facts about the benefits that would result from harnessing the Sahara's limitless reservoir of solar energy. (author)

  1. Solar hydrogen and solar electricity using mesoporous materials

    Science.gov (United States)

    Mahoney, Luther

    The development of cost-effective materials for effective utilization of solar energy is a major challenge for solving the energy problems that face the world. This thesis work relates to the development of mesoporous materials for solar energy applications in the areas of photocatalytic water splitting and the generation of electricity. Mesoporous materials were employed throughout the studies because of their favorable physico-chemical properties such as high surface areas and large porosities. The first project was related to the use of a cubic periodic mesoporous material, MCM-48. The studies showed that chromium loading directly affected the phase of mesoporous silica formed. Furthermore, within the cubic MCM-48 structure, the loading of polychromate species determined the concentration of solar hydrogen produced. In an effort to determine the potential of mesoporous materials, titanium dioxide was prepared using the Evaporation-Induced Self-Assembly (EISA) synthetic method. The aging period directly determined the amount of various phases of titanium dioxide. This method was extended for the preparation of cobalt doped titanium dioxide for solar simulated hydrogen evolution. In another study, metal doped systems were synthesized using the EISA procedure and rhodamine B (RhB) dye sensitized and metal doped titania mesoporous materials were evaluated for visible light hydrogen evolution. The final study employed various mesoporous titanium dioxide materials for N719 dye sensitized solar cell (DSSC) materials for photovoltaic applications. The materials were extensively characterized using powder X-ray diffraction (XRD), nitrogen physisorption, diffuse reflectance spectroscopy (DRS), UV-Vis spectroscopy, Fourier-Transform-Infrared Spectroscopy (FT-IR), Raman spectroscopy, chemisorption, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In addition, photoelectrochemical measurements were completed using

  2. From Extended Nanofluidics to an Autonomous Solar-Light-Driven Micro Fuel-Cell Device.

    Science.gov (United States)

    Pihosh, Yuriy; Uemura, Jin; Turkevych, Ivan; Mawatari, Kazuma; Kazoe, Yutaka; Smirnova, Adelina; Kitamori, Takehiko

    2017-07-03

    Autonomous micro/nano mechanical, chemical, and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro-power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage, and delivery to the sensor. Herein, we realized a solar-light-driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen fuel is then consumed by the μFC to generate electricity. Importantly, the by-product water returns back to the photocatalytic μFG via recirculation loop without losses. Both devices rely on novel phenomena in extended-nano-fluidic channels that ensure ultra-fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ca. 17.2 mWh cm(-2) at room temperature. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Solar-hydrogen generation and solar concentration (Conference Presentation)

    Science.gov (United States)

    Chinello, Enrico; Modestino, Miguel A.; Schüttauf, Jan-Willem; Lambelet, David; Delfino, Antonio; Dominé, Didier; Faes, Antonin; Despeisse, Matthieu; Bailat, Julien; Psaltis, Demetri; Fernandez Rivas, David; Ballif, Christophe; Moser, Christophe

    2016-09-01

    We successfully demonstrated and reported the highest solar-to-hydrogen efficiency with crystalline silicon cells and Earth-abundant electrocatalysts under unconcentrated solar radiation. The combination of hetero-junction silicon cells and a 3D printed Platinum/Iridium-Oxide electrolyzer has been proven to work continuously for more than 24 hours in neutral environment, with a stable 13.5% solar-to-fuel efficiency. Since the hydrogen economy is expected to expand to a global scale, we demonstrated the same efficiency with an Earth-abundant electrolyzer based on Nickel in a basic medium. In both cases, electrolyzer and photovoltaic cells have been specifically sized for their characteristic curves to intersect at a stable operating point. This is foreseen to guarantee constant operation over the device lifetime without performance degradation. The next step is to lower the production cost of hydrogen by making use of medium range solar concentration. It permits to limit the photoabsorbing area, shown to be the cost-driver component. We have recently modeled a self-tracking solar concentrator, able to capture sunlight within the acceptance angle range +/-45°, implementing 3 custom lenses. The design allows a fully static device, avoiding the external tracker that was necessary in a previously demonstrated +/-16° angular range concentrator. We will show two self-tracking methods. The first one relies on thermal expansion whereas the second method relies on microfluidics.

  4. Hydrogen Passivation in Mc-Si for Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effect of hydrogen passivation on multicrystalline silicon (mc-Si) used for solar cells is described, and the mechanism of hydrogen diffusion and passivation is also investigated. Then, the hydrogen passivation processes applied in industries and research laboratories are introduced. Finally the existing problems and the prospects of hydrogen passivation are reviewed.

  5. Hydrogen passivation of multi-crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    胡志华; 廖显伯; 刘祖明; 夏朝凤; 陈庭金

    2003-01-01

    The effects of hydrogen passivation on multi-crystalline silicon (mc-Si) solar cells are reported in this paper.Hydrogen plasma was generated by means of ac glow discharge in a hydrogen atmosphere. Hydrogen passivation was carried out with three different groups of mc-Si solar cells after finishing contacts. The experimental results demonstrated that the photovoltaic performances of the solar cell samples have been improved after hydrogen plasma treatment, with a relative increase in conversion efficiency up to 10.6%. A calculation modelling has been performed to interpret the experimental results using the model for analysis of microelectronic and photonic structures developed at Pennsylvania State University.

  6. Hydrogen Generation by Solar Photolysis of Water

    Science.gov (United States)

    Graetzel, Michael

    2004-03-01

    Prospects of near term fuel cell applications for transportation and communication have stimulated recently great interest in systems that can generate hydrogen through water cleavage by sunlight. A device that appears very promising to accomplish this goal is a tandem cell based on two superimposed photoactive layers [1]. The top layer consists of nanocrystalline oxide film absorbing the blue part of the solar spectrum and producing oxygen from water under light excitation. This is placed directly on top of a dye-sensitized nanocrystalline TiO2 film (DSC) capturing the green and red part of the solar spectrum. The voltage generated by this second photosystem enables hydrogen production to proceed without application of an external electric bias. The overall reaction corresponds to the splitting of water into hydrogen and oxygen by visible light. The maximum conversion efficiency achieved so far with these systems is about 6-7 electrode a nanocrystalline WO3 film. The use of nanoparticles for the top layer has several great advantages. They are translucent avoiding losses by light scattering and their small size is within the minority carrier diffusion length, allowing the valence band hole reaction with water at the particle surface to proceed with high efficiency. Recent work has focused on replacing the WO3 by semiconductor oxide absorbing a larger fraction of visible light than tungsten trioxide, e.g. Fe2O3.The principles and current state of this research will be briefly reviewed. Literature 1. M. Graetzel, "Photoelectrochemical Cells" Nature, 414, 332-344 (2001)

  7. Solar and Wind Technologies for Hydrogen Production Report to Congress

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2005-12-01

    DOE's Solar and Wind Technologies for Hydrogen Production Report to Congress summarizes the technology roadmaps for solar- and wind-based hydrogen production. Published in December 2005, it fulfills the requirement under section 812 of the Energy Policy Act of 2005.

  8. Solar hydrogen: harvesting light and heat from sun (Presentation Recording)

    Science.gov (United States)

    Guo, Liejin; Jing, Dengwei

    2015-09-01

    My research group in the State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF), Xi'an Jiaotong University has been focusing on renewable energy, especially solar hydrogen, for about 20 years. In this presentation, I will present the most recent progress in our group on solar hydrogen production using light and heat. Firstly, "cheap" photoelectrochemical and photocatalytic water splitting, including both nanostructured materials and pilot-scale demonstration in our group for light-driven solar hydrogen (artificial photosynthesis) will be introduced. Then I will make a deep introduction to the achievements on the thermal-driven solar hydrogen, i.e., biomass/coal gasification in supercritical water for large-scale and low-cost hydrogen production using concentrated solar light.

  9. Solar/hydrogen systems technologies. Volume II (Part 1 of 2). Solar/hydrogen systems assessment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Escher, W. J.D.; Foster, R. W.; Tison, R. R.; Hanson, J. A.

    1980-06-02

    Volume II of the Solar/Hydrogen Systems Assessment contract report (2 volumes) is basically a technological source book. Relying heavily on expert contributions, it comprehensively reviews constituent technologies from which can be assembled a wide range of specific solar/hydrogen systems. Covered here are both direct and indirect solar energy conversion technologies; respectively, those that utilize solar radiant energy input directly and immediately, and those that absorb energy from a physical intermediary, previously energized by the sun. Solar-operated hydrogen energy production technologies are also covered in the report. The single most prominent of these is water electrolysis. Utilization of solar-produced hydrogen is outside the scope of the volume. However, the important hydrogen delivery step is treated under the delivery sub-steps of hydrogen transmission, distribution and storage. An exemplary use of the presented information is in the synthesis and analysis of those solar/hydrogen system candidates documented in the report's Volume I. Morever, it is intended that broad use be made of this technology information in the implementation of future solar/hydrogen systems. Such systems, configured on either a distributed or a central-plant basis, or both, may well be of major significance in effecting an ultimate transition to renewable energy systems.

  10. Solar/hydrogen systems technologies. Volume II (Part 2 of 2). Solar/hydrogen systems assessment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Escher, W. J.D.; Foster, R. W.; Tison, R. R.; Hanson, J. A.

    1980-06-02

    Volume II of the Solar/Hydrogen Systems Assessment contract report (2 volumes) is basically a technological source book. Relying heavily on expert contributions, it comprehensively reviews constituent technologies from which can be assembled a wide range of specific solar/hydrogen systems. Covered here are both direct and indirect solar energy conversion technologies; respectively, those that utilize solar radiant energy input directly and immediately, and those that absorb energy from a physical intermediary, previously energized by the sun. Solar-operated hydrogen energy production technologies are also covered in the report. The single most prominent of these is water electrolysis. Utilization of solar-produced hydrogen is outside the scope of the volume. However, the important hydrogen delivery step is treated under the delivery sub-steps of hydrogen transmission, distribution and storage. An exemplary use of the presented information is in the synthesis and analysis of those solar/hydrogen system candidates documented in the report's Volume I. Moreover, it is intended that broad use be made of this technology information in the implementation of future solar/hydrogen systems. Such systems, configured on either a distributed or a central-plant basis, or both, may well be a major significance in effecting an ultimate transition to renewable energy systems.

  11. Solar Thermochemical Hydrogen Production Research (STCH)

    Energy Technology Data Exchange (ETDEWEB)

    Perret, Robert [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2011-05-01

    Eight cycles in a coordinated set of projects for Solar Thermochemical Cycles for Hydrogen production (STCH) were self-evaluated for the DOE-EERE Fuel Cell Technologies Program at a Working Group Meeting on October 8 and 9, 2008. This document reports the initial selection process for development investment in STCH projects, the evaluation process meant to reduce the number of projects as a means to focus resources on development of a few most-likely-to-succeed efforts, the obstacles encountered in project inventory reduction and the outcomes of the evaluation process. Summary technical status of the projects under evaluation is reported and recommendations identified to improve future project planning and selection activities.

  12. An assessment on hydrogen production using central receiver solar systems

    Science.gov (United States)

    Bilgen, C.; Bilgen, E.

    An assessment is presented on hydrogen production using a dedicated central receiver solar system concept coupled to two types of hydrogen producing processes, electrolysis and thermochemical. The study on solar electrolytic hydrogen was carried out using solar electricity and four different electrolytic technologies, namely, industrial unipolar 1980 and 1983 technologies, industrial bipolar and solid polymer electrolyte technology. The thermochemical process was the sulphur/iodine cycle, which is being developed by General Atomic Co. Systems, which is capable of producing about one-million GJ hydrogen per year, was developed at the conceptual level, and site specific computations were carried out. A general mathematical model was developed to predict the optical and thermal performance of the central receiver system coupled directly to the chemical plant. Cost models were developed for each subsystem based on the database published in the literature. Levelized and delevelized costs of solar hydrogen were then computed.

  13. Decentralized and direct solar hydrogen production: Towards a hydrogen economy in MENA region

    Energy Technology Data Exchange (ETDEWEB)

    Bensebaa, Farid; Khalfallah, Mohamed; Ouchene, Majid

    2010-09-15

    Hydrogen has certainly some advantages in spite of its high cost and low efficiency when compared to other energy vectors. Solar energy is an abundant, clean and renewable source of energy, currently competing with fossil fuel for water heating without subsidy. Photo-electrochemical, thermo-chemicals and photo-biological processes for hydrogen production processes have been demonstrated. These decentralised hydrogen production processes using directly solar energy do not require expensive hydrogen infrastructure for packaging and delivery in the short and medium terms. MENA region could certainly be considered a key area for a new start to a global deployment of hydrogen economy.

  14. IR characterization of hydrogen in crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Stavola, M., E-mail: michael.stavola@Lehigh.ed [Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States); Kleekajai, S.; Wen, L.; Peng, C. [Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States); Yelundur, V.; Rohatgi, A. [School of Electrical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Carnel, L. [REC Wafer AS, NO-3908 Porsgrunn (Norway); Kalejs, J. [American Capital Energy, N. Chelmsford, MA 01863 (United States)

    2009-12-15

    Hydrogen is commonly introduced into silicon solar cells to reduce the deleterious effects of defects and to increase cell efficiency. A process that is widely used by industry to introduce hydrogen is by the post-deposition annealing of a hydrogen-rich SiN{sub x} layer that is used as an anti-reflection coating. A number of questions about this hydrogen introduction process and hydrogen's subsequent interactions with defects have proved difficult to address because of the low concentration of hydrogen that is introduced into the Si bulk. We have used the fundamental knowledge of hydrogenated defects that has been revealed by recent investigations of impurity-H complexes to develop strategies by which hydrogen in silicon can be detected by IR spectroscopy with high sensitivity. The introduction of hydrogen into Si by the post-deposition annealing of a SiN{sub x} coating has been investigated.

  15. ANTS: Exploring the Solar System with an Autonomous Nanotechnology Swarm

    Science.gov (United States)

    Clark, P. E.; Curtis, S.; Rilee, M.; Truszkowski, W.; Marr, G.

    2002-01-01

    ANTS (Autonomous Nano-Technology Swarm), a NASA advanced mission concept, calls for a large (1000 member) swarm of pico-class (1 kg) totally autonomous spacecraft to prospect the asteroid belt. Additional information is contained in the original extended abstract.

  16. A study on the solar hydrogen production techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bozoglan, Elif [Department of Management, Taris Olive Oil, Agricultural, Industrial and Commercial Company, (Turkey); Midilli, Adnan [Energy Technologies, Turgut Kiran Maritime College, Marine Engineering, Rize University (Turkey); Hepbasli, Arif [Department of Mechanical Engineering, College of Engineering, King Saud University (Saudi Arabia)

    2011-07-01

    With the depletion of fossil fuels and the rising concerns about the environment, interest in green energy, which is both sustainable and clean, is growing. Among the different techniques, solar energy based hydrogen production appears to be one of the simpler and more convenient methods. Several solar hydrogen production methods exist and the aim of this paper is to determine the environmental and sustainability performances of an electrolyser. A solar hydrogen system was designed to meet the demands of 100 families in Misurata, Libya, whose average consumption is 268 kW and an exergy analysis was performed on the system. Results showed that the exergy destruction factor was 0.14 and the environmental destruction factor was 0.16. This study demonstrated that producing hydrogen using solar energy is an environmentally friendly and sustainable method which does not generate any greenhouse gases in the operating stage.

  17. Solar Hydrogen Fuel Cell Projects at Brooklyn Tech

    Science.gov (United States)

    Fedotov, Alex; Farah, Shadia; Farley, Daithi; Ghani, Naureen; Kuo, Emmy; Aponte, Cecielo; Abrescia, Leo; Kwan, Laiyee; Khan, Ussamah; Khizner, Felix; Yam, Anthony; Sakeeb, Khan; Grey, Daniel; Anika, Zarin; Issa, Fouad; Boussayoud, Chayama; Abdeldayem, Mahmoud; Zhang, Alvin; Chen, Kelin; Chan, Kameron Chuen; Roytman, Viktor; Yee, Michael

    2010-01-01

    This article describes the projects on solar hydrogen powered vehicles using water as fuel conducted by teams at Brooklyn Technical High School. Their investigations into the pure and applied chemical thermodynamics of hydrogen fuel cells and bio-inspired devices have been consolidated in a new and emerging sub-discipline that they define as solar…

  18. Solar Photovoltaic Hydrogen: The Technologies and Their Place in Our Roadmaps and Energy Economics

    Energy Technology Data Exchange (ETDEWEB)

    Kazmerski, L. L.; Broussard, K.

    2004-08-01

    Future solar photovoltaics-hydrogen systems are discussed in terms of the evolving hydrogen economy. The focus is on distributed hydrogen, relying on the same distributed-energy strengths of solar-photovoltaic electricity in the built environment. Solar-hydrogen residences/buildings, as well as solar parks, are presented. The economics, feasibility, and potential of these approaches are evaluated in terms of roadmap predictions on photovoltaic and hydrogen pathways-and whether solar-hydrogen fit in these strategies and timeframes. Issues with the ''hydrogen future'' are considered, and alternatives to this hydrogen future are examined.

  19. Solar photovoltaic hydrogen: the technologies and their place in our road-maps and energy economics

    Energy Technology Data Exchange (ETDEWEB)

    Kazmerski, L.L. [National Renewable Energy Laboratory, Golden, Colorado (United States); Broussard, K. [Southern Univ., Baton Rouge, LA (United States)

    2004-07-01

    Future solar photovoltaic-hydrogen systems are discussed in terms of the evolving hydrogen economy. The focus is on distributed hydrogen, relying on the same distributed-energy strengths of solar-photovoltaic electricity in the built environment. Solar-hydrogen residences/buildings, as well as solar parks, are presented. The economics, feasibility, and potential of these approaches are evaluated in terms of road-map predictions on photovoltaic and hydrogen pathways and whether solar-hydrogen fit in these strategies and time-frames. Issues with the ''hydrogen future'' are considered, and alternatives to this hydrogen future are examined. (authors)

  20. Selective production of hydrogen peroxide and oxidation of hydrogen sulfide in an unbiased solar photoelectrochemical cell

    DEFF Research Database (Denmark)

    Zong, Xu; Chen, Hongjun; Seger, Brian

    2014-01-01

    A solar-to-chemical conversion process is demonstrated using a photoelectrochemical cell without external bias for selective oxidation of hydrogen sulfide (H2S) to produce hydrogen peroxide (H2O2) and sulfur (S). The process integrates two redox couples anthraquinone/anthrahydroquinone and I−/I3...

  1. Powering Autonomous Sensors An Integral Approach with Focus on Solar and RF Energy Harvesting

    CERN Document Server

    Penella-López, María Teresa

    2011-01-01

    Autonomous sensors transmit data and power their electronics without using cables. They can be found in e.g. wireless sensor networks (WSNs) or remote acquisition systems. Although primary batteries provide a simple design for powering autonomous sensors, they present several limitations such as limited capacity and power density, and difficulty in predicting their condition and state of charge. An alternative is to extract energy from the ambient (energy harvesting). However, the reduced dimensions of most autonomous sensors lead to a low level of available power from the energy transducer. Thus, efficient methods and circuits to manage and gather the energy are a must. An integral approach for powering autonomous sensors by considering both primary batteries and energy harvesters is presented. Two rather different forms of energy harvesting are also dealt with: optical (or solar) and radiofrequency (RF). Optical energy provides high energy density, especially outdoors, whereas RF remote powering is possibly...

  2. Development of a low cost, portable solar hydrogen generation device

    Science.gov (United States)

    Rose, Kyle; Aggarwal, M. D.; Batra, Ashok; Wingo, Dennis

    2014-10-01

    Hydrogen is a clean energy source that is environmentally friendly and safe. It is well known that electrolysis is a common method used to produce hydrogen. Other high cost methods for hydrogen production can be countered by the development of this low cost pulse width modulated circuit, using direct current provided by naturally existing solar energy as a power source. Efforts are being made in the scientific community to produce a low cost, portable, solar hydrogen generating device for a number of clean energy applications such as fuel cells and energy storage. Proof of concept has already been tested in the laboratory and a small prototype system is being designed and fabricated in the workshop at Alabama A&M University. Our results of this study and details of the electronic circuit and the prototype are presented.

  3. Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M.; Stradins, P.

    2012-06-01

    Post-deposition hydrogenation by remote plasma significantly improves performance of heteroepitaxial silicon solar cells. Heteroepitaxial deposition of thin crystal silicon on sapphire for photovoltaics (PV) is an excellent model system for the study and improvement of deposition on inexpensive Al2O3-coated (100) biaxially-textured metal foils. Without hydrogenation, PV conversion efficiencies are less than 1% on our model system. Performance is limited by carrier recombination at electrically active dislocations that result from lattice mismatch, and other defects. We find that low-temperature hydrogenation at 350 degrees C is more effective than hydrogenation at 610 degrees C. In this work, we use measurements such as spectral quantum efficiency, secondary ion mass spectrometry (SIMS), and vibrational Si-H spectroscopies to understand the effects of hydrogenation on the materials and devices. Quantum efficiency increases most at red and green wavelengths, indicating hydrogenation is affecting the bulk more than the surface of the cells. SIMS shows there are 100X more hydrogen atoms in our cells than dangling bonds along dislocations. Yet, Raman spectroscopy indicates that only low temperature hydrogenation creates Si-H bonds; trapped hydrogen does not stably passivate dangling-bond recombination sites at high temperatures.

  4. Solar/hydrogen systems for the 1985 to 2000 time frame. Volume I. Solar/hydrogen systems assessment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Foster, R. W.; Tison, R. R.; Escher, W. J.D.; Hanson, J. A.

    1980-06-01

    The findings of a study of opportunities for commercialization of systems capable of producing hydrogen from solar energy are presented in two volumes. A compendium of monographs by specialists in the fields of solar energy conversion technologies, hydrogen production technologies and related technology descriptions from the general literature comprise Volume II. This data base was used to support an evaluation and selection process that identified four candidate solar/hydrogen systems best suited to commercialization within the next two decades. Volume I first reviews the background of the work and the methods used. Then an evaluation of the hydrogen product costs that might be achieved by the four selected candidate systems (photovoltaic/water electrolysis, thermal-heat engine/water electrolysis, wind energy/water electrolysis, small hydrogen/water electrolysis) is compared with the pricing structure and practices of the commodity gas market. Subsequently, product cost and market price match is noted to exist in the small user sector of the hydrogen marketplace. Barriers to and historical time lags in, commercialization of new technologies are then reviewed. Finally, recommendations for development and demonstration programs designed to accelerate the commercialization of the candidate systems are presented.

  5. Autonomous energy technological complex with hydrogen as the secondary energy carrier

    Energy Technology Data Exchange (ETDEWEB)

    Muminov, M.; Zakhidov, R. [AN Uzbekskoj SSR, Tashkent (Uzbekistan). Inst. Yadernoj Fiziki; Basteev, A.; Bazima, L. [Zhukovsky National Aerospace Univ. ' ' Kharkov Aviation Inst.' ' , Kharkov (Ukraine); Rashkovan, V. [Inst. Politecnico Nacional de Mexico, SEPI, Culhucan, La Escuela Superior de Ingenieria Mecanica Y Electrica (Mexico); Solovey, V.; Prognimak, A. [Podgorny Inst. of Mechanical Engineering Problems, National Academy of Sciences, Kharkov (Ukraine); Glazkov, V.; Golubenko, N. [Yangel State Design Office ' ' YUZHNOYE' ' (Ukraine)

    2001-07-01

    The energy-technological complex (ETC) destination is the transforming of primary sun/wind energy into electric one as well the sub-products fabrication. The ETC consists of the following constituent elements that should be characterized by the harmonized parameters: wind power station, photo-voltaic transformer, distiller, fuel cell, hydrogen and oxygen generator like the electrolyzer and compressed gases storing and supply system (SSS). The hydrogen and oxygen are generated in the electrolyzer and stored in the SSS and then used in fuel cell for standard electric energy generation. The desalination of seawater and sea salt yielding is the ETC output as well. The base ETC configuration with power 6 - 10 kW are considered. The operational peculiarities of ETC constituent element are considered as well. The creation and operational demonstration of the autonomous ETC are supported by STCU (projectaUZB-23j). (orig.)

  6. Scope for solar hydrogen power plants along Indian coasts

    Science.gov (United States)

    Hajra, Debdyut; Mukhopadhyay, Swarnav

    2016-09-01

    Energy is at the core of economic growth and development in the present day world. But relentless and unchecked use of harmful energy resources like fossil fuels (coil and oil), nuclear energy has taken a toll on mother nature. The energy coffers are being rapidly depleted and within a few years all of them will become empty, leaving nothing for the future generations to build on. Their constant usage has degraded the air quality and given way to land and water pollution. Scientists and world leaders have initiated a call for action to shift our dependence from currently popular energy sources to cleaner and renewable energy sources. Search for such energy sources have been going on for many years. Solar energy, wind energy, ocean energy, tidal energy, biofuel, etc. have caught the attention of people. Another such important which has become popular is 'Solar Hydrogen'. Many visionary scientists have called hydrogen the energy of the future. It is produced from water by direct or indirect use of sunlight in a sustainable manner. This paper discusses the current energy scenario, the importance of solar-hydrogen as a fuel and most importantly the scope for solar hydrogen power plants along Indian coastline.

  7. Solar/hydrogen systems assessment. Volume 1: Solar/hydrogen systems for the 1985 - 2000 time frame

    Science.gov (United States)

    Foster, R. W.; Tison, R. R.; Escher, W. J. D.; Hanson, J. A.

    1980-01-01

    Opportunities for commercialization of systems capable of producing hydrogen from solar energy were studied. The hydrogen product costs that might be achieved by the four selected candidate systems was compared with the pricing structure and practices of the commodity gas market. Subsequently, product cost and market price match was noted to exist in the small user sector of the hydrogen marketplace. Barriers to and historical time lags in, commercialization of new technologies are reviewed. Recommendations for development and demonstration programs designed to accelerate the commercialization of the candidate systems are presented.

  8. Solar/hydrogen systems for the 1985-2000 time frame - A review and assessment

    Science.gov (United States)

    Hanson, J. A.; Foster, R. W.; Escher, W. J. D.; Tison, R. R.

    1982-01-01

    A comprehensive state-of-the-art review of solar/hydrogen technologies has been conducted. From this, solar/hydrogen production systems which could be commercialized by the year 2000 have been characterized technically and economically. Incentives and disincentives for the early commercialization of four solar/hydrogen systems have been explored, conclusions drawn and recommendations made.

  9. III-V nitride semiconductors for solar hydrogen production

    Science.gov (United States)

    Parameshwaran, Vijay; Gallinat, Chad; Enck, Ryan W.; Sampath, Anand V.; Shen, Paul H.; Kuykendall, Tevye; Aloni, Shaul; Wraback, Michael; Clemens, Bruce M.

    2012-06-01

    Photoelectrochemical cells are devices that can convert solar radiation to hydrogen gas through a water decomposition process. In this process, energy is converted from incident photons to the bonds of the generated H2 molecules. The solar radiation absorption, electron-hole pair splitting, and photoelectrolysis half reactions all occur in the vicinity of the electrode-electrolyte interface. As a result, engineering the electrode material and its interaction with the electrolyte is important in investigating and improving the energy conversion process in these devices. III-V nitride materials are promising candidates for photoelectrochemical energy applications. We demonstrate solar-to-hydrogen conversion in these cells using p-type GaN and n-type InGaN as a photocathode and photoanode material, respectively. Additionally, we demonstrate heteroepitaxial MOCVD growth of GaP on Si, enabling future work in developing GaPN as a photocathode material.

  10. Black TiO2 for solar hydrogen conversion

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2017-06-01

    Full Text Available Titanium dioxide (TiO2 has been widely investigated for photocatalytic H2 evolution and photoelectrochemical (PEC water splitting since 1972. However, its wide bandgap (3.0–3.2 eV limits the optical absorption of TiO2 for sufficient utilization of solar energy. Blackening TiO2 has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities, and aroused widespread research interest. In this article, we reviewed the recent progress of black TiO2 for photocatalytic H2 evolution and PEC water splitting, along with detailed introduction to its unique structural features, optical property, charge carrier transfer property and related theoretical calculations. As summarized in this review article, black TiO2 could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting, and continuous efforts are deserved for improving its solar hydrogen efficiency.

  11. Solar-hydrogen energy system model for Libya

    Energy Technology Data Exchange (ETDEWEB)

    Eljrushi, G.S.

    1987-01-01

    A solar-hydrogen energy-system model for Libya was developed, obtaining relationships for and between the main energy and energy related parameters of Libya and the world. The parameters included are: population, energy demand, fossil-fuel production, fossil-fuel resources, hydrogen production, hydrogen introduction rates, energy prices, gross domestic product, pollution and quality of life. The trends of these parameters with and without hydrogen introduction were investigated over a period of time - through the year 2100. The results indicate that the fossil-fuel resources in Libya could be exhausted, due to production for local and export demands, within three to four decades unless serious measures for reducing production are taken. The results indicate that adopting solar-hydrogen energy system would extend the availability of fossil-fuel resources for a longer time period, reduce pollution, improve quality of life and establish a permanent energy system for Libya. It also shows that eventually Libya could export hydrogen in lieu of oil and natural gas.

  12. Hydrogen based energy storage for solar energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Vanhanen, J.P.; Hagstroem, M.T.; Lund, P.H. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Engineering Physics and Mathematics; Leppaenen, J.R.; Nieminen, J.P. [Neste Oy (Finland)

    1998-12-31

    Hydrogen based energy storage options for solar energy systems was studied in order to improve their overall performance. A 1 kW photovoltaic hydrogen (PV-H2) pilot-plant and commercial prototype were constructed and a numerical simulation program H2PHOTO for system design and optimisation was developed. Furthermore, a comprehensive understanding of conversion (electrolysers and fuel cells) and storage (metal hydrides) technologies was acquired by the project partners. The PV-H{sub 2} power system provides a self-sufficient solution for applications in remote locations far from electric grids and maintenance services. (orig.)

  13. High Efficiency Solar Thermochemical Reactor for Hydrogen Production.

    Energy Technology Data Exchange (ETDEWEB)

    McDaniel, Anthony H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-09-30

    This research and development project is focused on the advancement of a technology that produces hydrogen at a cost that is competitive with fossil-based fuels for transportation. A twostep, solar-driven WS thermochemical cycle is theoretically capable of achieving an STH conversion ratio that exceeds the DOE target of 26% at a scale large enough to support an industrialized economy [1]. The challenge is to transition this technology from the laboratory to the marketplace and produce hydrogen at a cost that meets or exceeds DOE targets.

  14. Solar Hydrogen Energy Systems Science and Technology for the Hydrogen Economy

    CERN Document Server

    Zini, Gabriele

    2012-01-01

    It is just a matter of time when fossil fuels will become unavailable or uneconomical to retrieve. On top of that, their environmental impact is already too severe. Renewable energy sources can be considered as the most important substitute to fossil energy, since they are inexhaustible and have a very low, if none, impact on the environment. Still, their unevenness and unpredictability are drawbacks that must be dealt with in order to guarantee a reliable and steady energy supply to the final user. Hydrogen can be the answer to these problems. This book presents the readers with the modeling, functioning and implementation of solar hydrogen energy systems, which efficiently combine different technologies to convert, store and use renewable energy. Sources like solar photovoltaic or wind, technologies like electrolysis, fuel cells, traditional and advanced hydrogen storage are discussed and evaluated together with system management and output performance. Examples are also given to show how these systems are ...

  15. Solar to hydrogen: Compact and cost effective CPV field for rooftop operation and hydrogen production

    KAUST Repository

    Burhan, Muhammad

    2016-11-25

    Current commercial CPV systems are designed as large units which are targeted to be installed in open desert fields with high DNI availability. It appeared that the CPV is among some of those technologies which gained very little attention of people, with less customers and market. For conventional PV systems, the installations at the rooftop of commercial and residential buildings have a significant share in the total installed capacity of PV systems. That is why for most of the countries, the PV installations at the rooftop of commercial and residential buildings are aimed to be increased to half of total installed PV. On the other hand, there is no commercial CPV system available to be suitable for rooftop operation, giving motivation for the development of CPV field of compact systems. This paper discusses the development of a CPV field for the rooftop operation, comprising of compact CPV system with cost effective but highly accurate solar tracking sensor and wireless master slave control. In addition, the performance of the developed CPV systems is evaluated for production of hydrogen, which can be used as energy carrier or energy storage and a maximum solar to hydrogen efficiency of 18% is obtained. However, due to dynamic nature of the weather data and throughout the day variations in the performance of CPV and electrolyser, the solar to hydrogen performance is proposed to be reported as daily and long term average efficiency. The CPV-Hydrogen system showed daily average conversion efficiency of 15%, with solar to hydrogen production rate of 218 kW h/kg.

  16. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor.

    Science.gov (United States)

    Xia, Xinhui; Luo, Jingshan; Zeng, Zhiyuan; Guan, Cao; Zhang, Yongqi; Tu, Jiangping; Zhang, Hua; Fan, Hong Jin

    2012-01-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO(2)/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseudocapacitance is clearly demonstrated, and the charge/discharge is indicated by reversible color changes (photochromism). In such an integrated device, the photogenerated electrons are utilized for H(2) generation and holes for pseudocapacitive charging, so that both the reductive and oxidative energies are captured and converted. Specific capacitances of 482 F g(-1) at 0.5 A g(-1) and 287 F g(-1) at 1 A g(-1) are obtained with TiO(2)/Ni(OH)(2) nanorod arrays. This study provides a new research strategy for integrated pseudocapacitor and solar energy application.

  17. Optimized autonomous operations of a 20 K space hydrogen sorption cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Borders, J.; Prina, M.; Pearson, D.; Bhandari, P. [California Inst. of Technology, Jet Propulsion Lab., Pasadena, CA (United States); Morgante, G. [California Inst. of Technology, Jet Propulsion Lab., Pasadena, CA (United States); IASF/CNR-Sezione di Bologna, Bologna (Italy)

    2004-08-01

    A fully redundant hydrogen sorption cryocooler is being developed for the European Space Agency Planck mission, dedicated to the measurement of the temperature anisotropies of the cosmic microwave background radiation with unprecedented sensitivity and resolution [Advances in Cryogenic Engineering 45A (2000) 499]. In order to achieve this ambitious scientific task, this cooler is required to provide a stable temperature reference ({approx}20 K) and appropriate cooling ({approx}1 W) to the two instruments on-board, with a flight operational lifetime of 18 months. During mission operations, communication with the spacecraft will be possible in a restricted time-window, not longer than 2 h/day. This implies the need for an operations control structure with the required robustness to safely perform autonomous procedures. The cooler performance depends on many operating parameters (such as the temperatures of the pre-cooling stages and the warm radiator), therefore the operation control system needs the capability to adapt to variations of these boundary conditions, while maintaining safe operating procedures. An engineering bread board (EBB) cooler was assembled and tested to evaluate the behavior of the system under conditions simulating flight operations and the test data were used to refine and improve the operation control software. In order to minimize scientific data loss, the cooler is required to detect all possible failure modes and to autonomously react to them by taking the appropriate action in a rapid fashion. Various procedures and schemes both general and specific in nature were developed, tested and implemented to achieve these goals. In general, the robustness to malfunctions was increased by implementing an automatic classification of anomalies in different levels relative to the seriousness of the error. The response is therefore proportional to the failure level. Specifically, the start-up sequence duration was significantly reduced, allowing a much

  18. Tool for optimal design and operation of hydrogen storage based autonomous energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Oberschachtsiek, B.; Lemken, D. [ZBT - Duisburg (Germany); Stark, M.; Krost, G. [Duisburg-Essen Univ. (Germany)

    2010-07-01

    Decentralized small scale electricity generation based on renewable energy sources usually necessitates decoupling of volatile power generation and consumption by means of energy storage. Hydrogen has proven as an eligible storage medium for mid- and long-term range, which - when indicated - can be reasonably complemented by accumulator short term storage. The selection of appropriate system components - sources, storage devices and the appertaining peripherals - is a demanding task which affords a high degree of freedom but, on the other hand, has to account for various operational dependencies and restrictions of system components, as well as for conduct of load and generation. An innovative tool facilitates the configuration and dimensioning of renewable energy based power supply systems with hydrogen storage paths, and allows for applying appropriate operation strategies. This tool accounts for the characteristics and performances of relevant power sources, loads, and types of energy storage, and also regards safety rules the energy system has to comply with. In particular, the tool is addressing small, detached and autonomous supply systems. (orig.)

  19. EXPERIMENTAL STUDY OF THE PRODUCTION OF SOLAR HYDROGEN IN ALGERIA

    Directory of Open Access Journals (Sweden)

    W. Bendaikha

    2015-08-01

    Full Text Available Hydrogen is a sustainable fuel option and one of the potential solutions for the current energy and environmental problems. In this study hydrogen is produced using a hydrogen generator with a Proton Exchange Membrane (PEM electrolyser. An experimental study is done in the Center of Development of the Renewable Energy, Algiers, Algeria.The experimental device contains essentially a photovoltaic module, a PEM electrolyser, a gasometer and the devices of measures of characteristics of the PEM electrolyser as well as two pyranometers for the horizontal and diffuse global radiance registration. This system in pilots scale is permitted on the one hand, to measured and analyzed the characteristics: of the PEM electrolyser for two different pressures of working (Patm and P=3 bar, on the other hand, to study the volume of hydrogen produces in the time with different sources of electrical power (generator, photovoltaic module, fluorescent lamp, the efficiency for every case is calculated and compared. We present in this paper the variation of the solar hydrogen flow rate produced according to the global radiance and according to the time for a typical day’s of August.

  20. Solar-driven hydrogen production in green algae.

    Science.gov (United States)

    Burgess, Steven J; Tamburic, Bojan; Zemichael, Fessehaye; Hellgardt, Klaus; Nixon, Peter J

    2011-01-01

    The twin problems of energy security and global warming make hydrogen an attractive alternative to traditional fossil fuels with its combustion resulting only in the release of water vapor. Biological hydrogen production represents a renewable source of the gas and can be performed by a diverse range of microorganisms from strict anaerobic bacteria to eukaryotic green algae. Compared to conventional methods for generating H(2), biological systems can operate at ambient temperatures and pressures without the need for rare metals and could potentially be coupled to a variety of biotechnological processes ranging from desalination and waste water treatment to pharmaceutical production. Photobiological hydrogen production by microalgae is particularly attractive as the main inputs for the process (water and solar energy) are plentiful. This chapter focuses on recent developments in solar-driven H(2) production in green algae with emphasis on the model organism Chlamydomonas reinhardtii. We review the current methods used to achieve sustained H(2) evolution and discuss possible approaches to improve H(2) yields, including the optimization of culturing conditions, reducing light-harvesting antennae and targeting auxiliary electron transport and fermentative pathways that compete with the hydrogenase for reductant. Finally, industrial scale-up is discussed in the context of photobioreactor design and the future prospects of the field are considered within the broader context of a biorefinery concept.

  1. Design of the Wireless Telecommunication System of an Autonomous Solar Vehicle

    OpenAIRE

    Moyà Porcel, Rafel

    2011-01-01

    Projecte de final de carrera fet en col.laboració amb ETH-Swiss Federal Institute of Technology. English: The Automatic Control Lab at the Swiss Federal Institute of technology Zurich (ETH) is currently designing and building an autonomously driving solar vehicle (ASV). Having the size of a Radio Control Model Car, the main purpose of it is to serve as a research platform to test new control methods and strategies. The ASV project has been divided into different stages such as mechanical d...

  2. Analysis of a hydrogen-solar system for the Brazil; Analise de um sistema hidrogenio-solar para o Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Samuel N.M. de; Mendes, Nathan; Lima, Lutero C. de [Uberlandia Univ., MG (Brazil). Dept. de Engenharia Mecanica; Veziroglu, T.N. [Miami Univ., Coral Gables, FL (United States)

    1995-07-01

    In this article it is proposed the study of technical aspects and costs of the implantation of a system of solar hydrogen utilization in Brazil. Forecasts are made of the total photovoltaic cell, water demand for the production of electrolytic hydrogen, investments, benefits and comparative price between fossil fuel and hydrogen. (author)

  3. Raman spectroscopy of PIN hydrogenated amorphous silicon solar cells

    Science.gov (United States)

    Keya, Kimitaka; Torigoe, Yoshihiro; Toko, Susumu; Yamashita, Daisuke; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) is a key issue for enhancing competitiveness in solar cell market. A-Si:H films with a lower density of Si-H2 bonds shows higher stability. Here we identified Si-H2 bonds in PIN a-Si:H solar cells fabricated by plasma CVD using Raman spectroscopy. A-Si:H solar cell has a structure of B-doped μc-SiC:H (12.5 nm)/ non-doped a-Si:H (250nm)/ P-doped μc-Si:H (40 nm) on glass substrates (Asahi-VU). By irradiating HeNe laser light from N-layer, peaks correspond to Si-H2 bonds (2100 cm-1) and Si-H bonds (2000 cm-1) have been identified in Raman scattering spectra. The intensity ratio of Si-H2 and Si-H ISiH2/ISiH is found to correlate well to light induced degradation of the cells Therefore, Raman spectroscopy is a promising method for studying origin of light-induced degradation of PIN solar cells.

  4. Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30.

    Science.gov (United States)

    Jia, Jieyang; Seitz, Linsey C; Benck, Jesse D; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S; Jaramillo, Thomas F

    2016-10-31

    Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

  5. Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30%

    Science.gov (United States)

    Jia, Jieyang; Seitz, Linsey C.; Benck, Jesse D.; Huo, Yijie; Chen, Yusi; Ng, Jia Wei Desmond; Bilir, Taner; Harris, James S.; Jaramillo, Thomas F.

    2016-10-01

    Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

  6. A Solar Energy Powered Autonomous Wireless Actuator Node for Irrigation Systems

    Science.gov (United States)

    Lajara, Rafael; Alberola, Jorge; Pelegrí-Sebastiá, José

    2011-01-01

    The design of a fully autonomous and wireless actuator node (“wEcoValve mote”) based on the IEEE 802.15.4 standard is presented. The system allows remote control (open/close) of a 3-lead magnetic latch solenoid, commonly used in drip irrigation systems in applications such as agricultural areas, greenhouses, gardens, etc. The very low power consumption of the system in conjunction with the low power consumption of the valve, only when switching positions, allows the system to be solar powered, thus eliminating the need of wires and facilitating its deployment. By using supercapacitors recharged from a specifically designed solar power module, the need to replace batteries is also eliminated and the system is completely autonomous and maintenance free. The “wEcoValve mote” firmware is based on a synchronous protocol that allows a bidirectional communication with a latency optimized for real-time work, with a synchronization time between nodes of 4 s, thus achieving a power consumption average of 2.9 mW. PMID:22346580

  7. Solar powered hydrogen generating facility and hydrogen powered vehicle fleet. Final technical report, August 11, 1994--January 6, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Provenzano, J.J.

    1997-04-01

    This final report describes activities carried out in support of a demonstration of a hydrogen powered vehicle fleet and construction of a solar powered hydrogen generation system. The hydrogen generation system was permitted for construction, constructed, and permitted for operation. It is not connected to the utility grid, either for electrolytic generation of hydrogen or for compression of the gas. Operation results from ideal and cloudy days are presented. The report also describes the achievement of licensing permits for their hydrogen powered trucks in California, safety assessments of the trucks, performance data, and information on emissions measurements which demonstrate performance better than the Ultra-Low Emission Vehicle levels.

  8. Computational design of materials for solar hydrogen generation

    Science.gov (United States)

    Umezawa, Naoto

    Photocatalysis has a great potential for the production of hydrogen from aquerous solution under solar light. In this talk, two different approaches toward the computational materials desing for solar hydrogen generation will be presented. Tin (Sn), which has two major oxidation states, Sn2+ and Sn4+, is abundant on the earth's crust. Recently, visible-light responsive photocatalytc H2 evolution reaction was identified over a mixed valence tin oxide Sn3O4. We have carried out crystal structure prediction for mixed valence tin oxides in different atomic compositions under ambient pressure condition using advanced computational methods based on the evolutionary crystal-structure search and density-functional theory. The predicted novel crystal structures realize the desirable band gaps and band edge positions for H2 evolution under visible light irradiation. It is concluded that multivalent tin oxides have a great potential as an abundant, cheap and environmentally-benign solar-energy conversion photofunctional materials. Transition metal doping is effective for sensitizing SrTiO3 under visible light. We have theoretically investigated the roles of the doped Cr in STO based on hybrid density-functional calculations. Cr atoms are preferably substituting for Ti under any equilibrium growth conditions. The lower oxidation state Cr3+, which is stabilized under an n-type condition of STO, is found to be advantageous for the photocatalytic performance. It is firther predicted that lanthanum is the best codopant for stabilizing the favorable oxidation state, Cr3+. The prediction was validated by our experiments that La and Cr co-doped STO shows the best performance among examined samples. This work was supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) and International Research Fellow program of Japan Society for the Promotion of Science (JSPS) through project P14207.

  9. Neutral Hydrogen and Its Emission Lines in the Solar Corona

    Science.gov (United States)

    Vial, Jean-Claude; Chane-Yook, Martine

    2016-12-01

    Since the Lyman-α rocket observations of Gabriel ( Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic-equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisional and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations ( e.g. Lα from Ultraviolet Coronal Spectrometer) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 Å wide) bandpass filter.

  10. Hydrogen passivation of polycrystalline Si thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gorka, Benjamin

    2010-12-15

    Hydrogen passivation is a key process step in the fabrication of polycrystalline Si (poly-Si) thin film solar cells. In this work a parallel plate rf plasma setup was used for the hydrogen passivation treatment. The main topics that have been investigated are (i) the role of plasma parameters (like hydrogen pressure, electrode gap and plasma power), (ii) the dynamics of the hydrogen treatment and (iii) passivation of poly-Si with different material properties. Passivation was characterized by measuring the open-circuit voltage V{sub OC} of poly-Si reference samples. Optimum passivation conditions were found by measurements of the breakdown voltage V{sub brk} of the plasma for different pressures p and electrode gaps d. For each pressure, the best passivation was achieved at a gap d that corresponded to the minimum in V{sub brk}. Plasma simulations were carried out, which indicate that best V{sub OC} corresponds to a minimum in ion energy. V{sub OC} was not improved by a larger H flux. Investigations of the passivation dynamic showed that a plasma treatment in the lower temperature range ({<=}400 C) is slow and takes several hours for the V{sub OC} to saturate. Fast passivation can be successfully achieved at elevated temperatures around 500 C to 600 C with a plateau time of 10 min. It was found that prolonged hydrogenation leads to a loss in V{sub OC}, which is less pronounced within the observed optimum temperature range (500 C-600 C). Electron beam evaporation has been investigated as an alternative method to fabricate poly-Si absorbers. The material properties have been tuned by alteration of substrate temperature T{sub dep}=200-700 C and were characterized by Raman, ESR and V{sub OC} measurements. Largest grains were obtained after solid phase crystallization (SPC) of a-Si, deposited in the temperature range of 300 C. The defect concentration of Si dangling bonds was lowered by passivation by about one order of magnitude. The lowest dangling bond concentration

  11. Solar photochemical production of HBr for off-peak electrolytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Heaton, H. [Solar Reactor Technologies Inc., Miami, FL (United States)

    1996-10-01

    Progress is reported on the development of a unique and innovative hydrogen production concept utilizing renewable (Solar) energy and incorporating energy storage. The concept is based on a solar-electrolytic system for production of hydrogen and oxygen. It employs water, bromine, solar energy, and supplemental electrical power. The process consumes only water, sunlight and off-peak electricity, and produces only hydrogen, oxygen, and peaking electrical power. No pollutants are emitted, and fossil fuels are not consumed. The concept is being developed by Solar Reactor Technologies, Inc., (SRT) under the auspices of a Cooperative Agreement with the U.S. Department of Energy (DOE).

  12. Broad Spectrum Photoelectrochemical Diodes for Solar Hydrogen Generation

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Craig A.

    2014-11-26

    Under program auspices we have investigated material chemistries suitable for the solar generation of hydrogen by water photoelectrolysis. We have built upon, and extended, our knowledge base on the synthesis and application of TiO2 nanotube arrays, a material architecture that appears ideal for water photoelectrolysis. To date we have optimized, refined, and greatly extended synthesis techniques suitable for achieving highly ordered TiO2 nanotube arrays of given length, wall thickness, pore diameter, and tube-to-tube spacing for use in water photoelectrolysis. We have built upon this knowledge based to achieve visible light responsive, photocorrosion stable n-type and p-type ternary oxide nanotube arrays for use in photoelectrochemical diodes.

  13. Solar hydrogen production on some water splitting photocatalysts

    Science.gov (United States)

    Takata, Tsuyoshi; Hisatomi, Takashi; Domen, Kazunari

    2016-09-01

    Photocatalytic overall water splitting into H2 and O2 is expected to be a promising method for the efficient utilization of solar energy. The design of optimal photocatalyst structures is a key to efficient overall water splitting, and the development of photocatalysts which can efficiently convert large portion of visible light spectrum has been required. Recently, a series of complex perovskite type transition metal oxynitrides, LaMgxT 1-xO1+3xN2-3x, was developed as photocatalysts for direct water splitting operable at wide wavelength of visible light. In addition two-step excitation water splitting via a novel photocatalytic device termed as photocatalyst sheet was developed. This consists of two types of semiconductors (hydrogen evolution photocatalyst and oxygen evolution photocatalyst) particles embedded in a conductive layer, and showed high efficiency for overall water splitting. These recent advances in photocatalytic water splitting were introduced.

  14. Solar photo-degradation of a pharmaceutical wastewater effluent in a semi-industrial autonomous plant.

    Science.gov (United States)

    Expósito, Antonio J; Durán, Antonio; Monteagudo, José M; Acevedo, Alba

    2016-05-01

    An industrial wastewater effluent coming from a pharmaceutical laboratory has been treated in a semi-industrial autonomous solar compound parabolic collector (CPC) plant. A photo-Fenton process assisted with ferrioxalate has been used. Up to 79% of TOC can be removed in 2 h depending on initial conditions when treating an aqueous effluent containing up to 400 ppm of initial organic carbon concentration (TOC). An initial ratio of Fe(II)/TOC higher than 0.5 guarantees a high removal. It can be seen that most of TOC removal occurs early in the first hour of reaction. After this time, mineralization was very slow, although H2O2 was still present in solution. Indeed it decomposed to form oxygen in inefficient reactions. It is clear that remaining TOC was mainly due to the presence of acetates which are difficult to degrade.

  15. Electrochemical preparation of hematite nanostructured films for solar hydrogen production

    Directory of Open Access Journals (Sweden)

    Ebadzadeh T.

    2012-10-01

    Full Text Available Photoelectrochemical water splitting is a clean and promising technique for using a renewable source of energy, i.e., solar energy, to produce hydrogen. In this work electrochemical formation of iron oxyhydroxide and its conversion to hematite (α- Fe2O3 through thermal treatment have been studied. Oxyhydroxide iron compounds have been prepared onto SnO2/F covered glass substrate by potential cycling with two different potential sweep rate values; then calcined at 520 °C in air to obtain α-Fe2O3 nanostrutured films for their implementation as photoanode in a photoelectrochemical cell. X-ray diffraction analysis allowed finding that iron oxides films have nanocrystalline character. Scanning electron microscopy revealed that films have nanostructured morphology. The obtained results are discussed considering the influence of potential sweep rate employed during the preparation of iron oxyhydroxide film on optical, structural and morphological properties of hematite nanostructured films. Results show that films have acceptable characteristics as photoanode in a photoelectrochemical cell for hydrogen generation from water.

  16. Neutral Hydrogen and its Emission Lines in the Solar Corona

    CERN Document Server

    Vial, Jean-Claude

    2016-01-01

    Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisionnal and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun cente...

  17. Quantum molecular dynamics simulations of hydrogen production and solar cells

    Science.gov (United States)

    Mou, Weiwei

    The global energy crisis presents two major challenges for scientists around the world: Producing cleaner energy which is sustainable for the environment; And improving the efficiency of energy production as well as consumption. It is crucial and yet elusive to understand the atomistic mechanisms and electronic properties, which are needed in order to tackle those challenges. Quantum molecular dynamics simulations and nonadiabatic quantum molecular dynamics are two of the dominant methods used to address the atomistic and electronic properties in various energy studies. This dissertation is an ensemble of three studies in energy research: (1) Hydrogen production from the reaction of aluminum clusters with water to provide a renewable energy cycle; (2) The photo-excited charge transfer and recombination at a quaterthiophene/zinc oxide interface to improve the power conversion efficiency of hybrid poly(3-hexylthiophene) (P3HT) /ZnO solar cells; and (3) the charge transfer at a rubrene/C60 interface to understand why phenyl groups in rubrene improve the performance of rubrene/C60 solar cells.

  18. The Solar Wind Charge-Exchange Production Factor for Hydrogen

    CERN Document Server

    Kuntz, K D; Collier, M R; Connor, H K; Cravens, T E; Koutroumpa, D; Porter, F S; Robertson, I P; Sibeck, D G; Snowden, S L; Thomas, N E; Wash, B M

    2015-01-01

    The production factor, or broad band averaged cross-section, for solar wind charge-exchange with hydrogen producing emission in the ROSAT 1/4 keV (R12) band is $3.8\\pm0.2\\times10^{-20}$ count degree$^{-2}$ cm$^4$. This value is derived from a comparison of the Long-Term (background) Enhancements in the ROSAT All-Sky Survey with magnetohysdrodynamic simulations of the magnetosheath. This value is 1.8 to 4.5 times higher than values derived from limited atomic data, suggesting that those values may be missing a large number of faint lines. This production factor is important for deriving the exact amount of 1/4 keV band flux that is due to the Local Hot Bubble, for planning future observations in the 1/4 keV band, and for evaluating proposals for remote sensing of the magnetosheath. The same method cannot be applied to the 3/4 keV band as that band, being composed primarily of the oxygen lines, is far more sensitive to the detailed abundances and ionization balance in the solar wind. We also show, incidentally,...

  19. Bibliographic Review about Solar Hydrogen Production Through Thermochemical Cycles; Revision Bibliografica sobre la Produccion de Hidrogeno Solar Mediante Ciclos Termoquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.

    2007-12-28

    This report presents a summary of the different thermical processes used to obtain hydrogen through solar energy, paying more attention to the production of hydrogen from water through thermochemical cycles. In this aspect, it is briefly described the most interesting thermochemical cycles, focusing on thermochemical cycles based on oxides. (Author) 25 refs.

  20. Bibliographic Review about Solar Hydrogen Production Through Thermochemical Cycles; Revision Bibliografica sobre la Produccion de Hidrogeno Solar Mediante Ciclos Termoquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.

    2008-08-06

    This report presents a summary of the different thermical processes used to obtain hydrogen through solar energy, paying more attention to the production of hydrogen from water through thermochemical cycles. In this aspect, it is briefly y described the most interesting thermochemical cycles, focusing on thermochemical cycles based on oxides. (Author) 25 refs.

  1. The Autonomous House: A Bio-Hydrogen Based Energy Self-Sufficient Approach

    Directory of Open Access Journals (Sweden)

    Ming-jen Cheng

    2009-04-01

    Full Text Available In the wake of the greenhouse effect and global energy crisis, finding sources of clean, alternative energy and developing everyday life applications have become urgent tasks. This study proposes the development of an "autonomous house" emphasizing the use of modern green energy technology to reduce environmental load, achieve energy autonomy and use energy intelligently in order to create a sustainable, comfortable living environment. The houses' two attributes are: (1 a self-sufficient energy cycle and (2 autonomous energy control to maintain environmental comfort. The autonomous house thus combines energy-conserving, carbon emission-reducing passive design with active elements needed to maintain a comfortable environment.

  2. The autonomous house: a bio-hydrogen based energy self-sufficient approach.

    Science.gov (United States)

    Chen, Shang-Yuan; Chu, Chen-Yeon; Cheng, Ming-Jen; Lin, Chiu-Yue

    2009-04-01

    In the wake of the greenhouse effect and global energy crisis, finding sources of clean, alternative energy and developing everyday life applications have become urgent tasks. This study proposes the development of an "autonomous house" emphasizing the use of modern green energy technology to reduce environmental load, achieve energy autonomy and use energy intelligently in order to create a sustainable, comfortable living environment. The houses' two attributes are: (1) a self-sufficient energy cycle and (2) autonomous energy control to maintain environmental comfort. The autonomous house thus combines energy-conserving, carbon emission-reducing passive design with active elements needed to maintain a comfortable environment.

  3. The electrohydraulic balance of the solar heat storage with autonomous power supply

    Directory of Open Access Journals (Sweden)

    M. K. Marahtanov

    2014-01-01

    Full Text Available The introduction of the paper emphasizes an increasingly important role of alternative power sources nowadays. At the same time, a solar collector (suntrap is one of the most frequent techniques to use the solar energy. It is an absorber that picks up solar radiation and heats a heat carrier circulating in the close loop. Then the heat is transferred to the heat accumulator that is integrated in the hot-tap water system (HWS.The paper presents a prospective circuit of the solar collector. It differs from the traditional one because, in addition to absorbing panel, it uses photoconverters to generate electric power for the circulating pump. The advantage of this system is that for operation such a solar energy converter has no need in external power sources, i.e. it is autonomous. The need to calculate the essential thermo-physical parameters that ensure no-break system operation was stated as a main objective of the work.The suggested circuit has a photocell panel to convert solar radiation into dc voltage of 12 V. In case of a lack of the solar energy an accumulator battery can be used for feeding. To ensure the no-break supply of power an adaptor is offered.To calculate a density distribution of solar radiation a sine law is offered depending on the time of day and geographical locality. This dependence was used to obtain the expressions for calculating the water temperature in boiler over daytime.Further, the calculations have been done for the operating conditions under which an efficient heat exchange will be provided with the minimum consumption of electric power for the heat carrier circulation in the first loop. For this purpose, a pump power was calculated depending on consumption and hydraulic losses of head in the pipeline. As a minimum required consumption the value has been chosen at which a laminar flow regime changes to the turbulent one because of the most efficient heat exchange being both in collector and in heat accumulator

  4. Mapping the coronal hydrogen temperature in view of the forthcoming coronagraph observations by Solar Orbiter

    Science.gov (United States)

    Dolei, S.; Spadaro, D.; Ventura, R.

    2016-08-01

    Context. Synergistic visible light and ultraviolet coronagraphic observations are essential to investigate the link of the Sun to the inner heliosphere through the study of the dynamic properties of the solar wind. Aims: We perform spectroscopic mapping of the outer solar corona to constitute a statistically significant database of neutral hydrogen coronal temperatures, which is suitable for overcoming the lack of spectrometric information in observations performed by coronagraphs that are solely equipped for visible light and ultraviolet imaging; these include the forthcoming Metis instrument on board Solar Orbiter. Methods: We systematically analysed neutral hydrogen Lyα line data that was obtained by UVCS/SOHO observations of the extended solar corona relevant to a lot of polar, mid-latitude and equatorial structures at different phases of solar activity, and collected far longer than a whole solar cycle (1996-2012). Results: We created a database consisting in both the neutral hydrogen temperature components, which are perpendicular and parallel to the radially symmetric coronal magnetic field lines, as a function of the heliocentric distance and polar angle and for different phases of the solar activity cycle. We validated the reliability of the constituted neutral hydrogen temperature database, investigating a new set of UVCS Lyα data with the Doppler dimming technique. The solar wind outflow velocities obtained by adopting both the neutral hydrogen temperature distribution directly derived from the observed Lyα profiles and those taken from our database well agree within the uncertainties.

  5. A Technical and Economic Review of Solar Hydrogen Production Technologies

    Science.gov (United States)

    Wilhelm, Erik; Fowler, Michael

    2006-01-01

    Hydrogen energy systems are being developed to replace fossil fuels-based systems for transportation and stationary application. One of the challenges facing the widespread adoption of hydrogen as an energy vector is the lack of an efficient, economical, and sustainable method of hydrogen production. In the short term, hydrogen produced from…

  6. Bio-inspired co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie; Vesborg, Peter Christian Kjærgaard;

    2011-01-01

    part of the spectrum is utilized for hydrogen evolution while the blue part is reserved for the more difficult oxygen evolution. The samples have been illuminated with a simulated red part of the solar spectrum i.e. long wavelength (" > 620 nm) part of simulated AM 1.5G radiation. The current densities...... deposited on various supports. It will be demonstrated how this overpotential can be eliminated by depositing the same type of hydrogen evolution catalyst on p-type Si which can harvest the red part of the solar spectrum. Such a system could constitute the cathode part of a tandem dream device where the red...... at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10%. The experimental observations are supported by DFT calculations of the Mo3S4 cluster adsorbed on the hydrogen-terminated silicon surface providing insights...

  7. Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma

    CERN Document Server

    Maruca, Bennett A; Sorriso-Valvo, Luca; Kasper, Justin C; Stevens, Michael L

    2013-01-01

    In situ observations of the solar wind frequently show the temperature of $\\alpha$-particles (fully ionized helium), $T_\\alpha$, to significantly differ from that of protons (ionized hydrogen), $T_p$. Many heating processes in the plasma act preferentially on $\\alpha$-particles, even as collisions among ions act to gradually establish thermal equilibrium. Measurements from the $\\textit{Wind}$ spacecraft's Faraday cups reveal that, at $r=1.0\\ \\textrm{AU}$ from the Sun, the observed values of the $\\alpha$-proton temperature ratio, $\\theta_{\\alpha p} \\equiv T_\\alpha\\,/\\,T_p$ has a complex, bimodal distribution. This study applied a simple model for the radial evolution of $\\theta_{\\alpha p}$ to these data to compute expected values of $\\theta_{\\alpha p}$ at $r=0.1\\ \\textrm{AU}$. These inferred $\\theta_{\\alpha p}$-values have no trace of the bimodality seen in the $\\theta_{\\alpha p}$-values measured at $r=1.0\\ \\textrm{AU}$ but are instead consistent with the actions of the known mechanisms for $\\alpha$-particle p...

  8. The effect of primordial hydrogen/helium fractionation on the solar neutrino flux

    Science.gov (United States)

    Wheeler, J. C.; Cameron, A. G. W.

    1975-01-01

    If hydrogen and helium are immiscible below some critical temperature, gravitational separation could occur in the proto-sun, resulting in a nearly pure helium core and a nearly pure hydrogen shell. We have constructed solar models according to this scenario and find the neutrino flux reduced to 1.5-3 SNU.

  9. Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

    Science.gov (United States)

    Hooke, Rebecca; Pearson, Andy; O'Hagan, John

    2014-01-01

    Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown.

  10. Solar Thermal Upper Stage Liquid Hydrogen Pressure Control Testing

    Science.gov (United States)

    Moore, J. D.; Otto, J. M.; Cody, J. C.; Hastings, L. J.; Bryant, C. B.; Gautney, T. T.

    2015-01-01

    High-energy cryogenic propellant is an essential element in future space exploration programs. Therefore, NASA and its industrial partners are committed to an advanced development/technology program that will broaden the experience base for the entire cryogenic fluid management community. Furthermore, the high cost of microgravity experiments has motivated NASA to establish government/aerospace industry teams to aggressively explore combinations of ground testing and analytical modeling to the greatest extent possible, thereby benefitting both industry and government entities. One such team consisting of ManTech SRS, Inc., Edwards Air Force Base, and Marshall Space Flight Center (MSFC) was formed to pursue a technology project designed to demonstrate technology readiness for an SRS liquid hydrogen (LH2) in-space propellant management concept. The subject testing was cooperatively performed June 21-30, 2000, through a partially reimbursable Space Act Agreement between SRS, MSFC, and the Air Force Research Laboratory. The joint statement of work used to guide the technical activity is presented in appendix A. The key elements of the SRS concept consisted of an LH2 storage and supply system that used all of the vented H2 for solar engine thrusting, accommodated pressure control without a thermodynamic vent system (TVS), and minimized or eliminated the need for a capillary liquid acquisition device (LAD). The strategy was to balance the LH2 storage tank pressure control requirements with the engine thrusting requirements to selectively provide either liquid or vapor H2 at a controlled rate to a solar thermal engine in the low-gravity environment of space operations. The overall test objective was to verify that the proposed concept could enable simultaneous control of LH2 tank pressure and feed system flow to the thruster without necessitating a TVS and a capillary LAD. The primary program objectives were designed to demonstrate technology readiness of the SRS concept

  11. High Efficiency Generation of Hydrogen Fuels Using Solar Thermochemical Splitting of Water

    Energy Technology Data Exchange (ETDEWEB)

    Heske, Clemens; Moujaes, Samir; Weimer, Alan; Wong, Bunsen; Siegal, Nathan; McFarland, Eric; Miller, Eric; Lewis, Michele; Bingham, Carl; Roth, Kurth; Sabacky, Bruce; Steinfeld, Aldo

    2011-09-29

    The objective of this work is to identify economically feasible concepts for the production of hydrogen from water using solar energy. The ultimate project objective was to select one or more competitive concepts for pilot-scale demonstration using concentrated solar energy. Results of pilot scale plant performance would be used as foundation for seeking public and private resources for full-scale plant development and testing. Economical success in this venture would afford the public with a renewable and limitless source of energy carrier for use in electric power load-leveling and as a carbon-free transportation fuel. The Solar Hydrogen Generation Research (SHGR) project embraces technologies relevant to hydrogen research under the Office of Hydrogen Fuel Cells and Infrastructure Technology (HFCIT) as well as concentrated solar power under the Office of Solar Energy Technologies (SET). Although the photoelectrochemical work is aligned with HFCIT, some of the technologies in this effort are also consistent with the skills and technologies found in concentrated solar power and photovoltaic technology under the Office of Solar Energy Technologies (SET). Hydrogen production by thermo-chemical water-splitting is a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or a combination of heat and electrolysis instead of pure electrolysis and meets the goals for hydrogen production using only water and renewable solar energy as feed-stocks. Photoelectrochemical hydrogen production also meets these goals by implementing photo-electrolysis at the surface of a semiconductor in contact with an electrolyte with bias provided by a photovoltaic source. Here, water splitting is a photo-electrolytic process in which hydrogen is produced using only solar photons and water as feed-stocks. The thermochemical hydrogen task engendered formal collaborations among two universities, three national laboratories and two private sector

  12. Multi-criteria analysis on how to select solar radiation hydrogen production system

    Energy Technology Data Exchange (ETDEWEB)

    Badea, G.; Naghiu, G. S., E-mail: naghiu.george@gmail.com; Felseghi, R.-A.; Giurca, I., E-mail: giurca-ioan@yahoo.com [Technical University of Cluj-Napoca, Faculty of Building Services Engineering, Boulevard December 21, no. 128-130, Cluj-Napoca, 400604 (Romania); Răboacă, S. [National R& D Institute for Cryogenic and Isotopic Technologies, str. Uzinei, no. 4, Rm. Vălcea, 240050 (Romania); Aşchilean, I. [SC ACI Cluj SA, Avenue Dorobanţilor, no. 70, Cluj-Napoca, 400609 (Romania)

    2015-12-23

    The purpose of this article is to present a method of selecting hydrogen-production systems using the electric power obtained in photovoltaic systems, and as a selecting method, we suggest the use of the Advanced Multi-Criteria Analysis based on the FRISCO formula. According to the case study on how to select the solar radiation hydrogen production system, the most convenient alternative is the alternative A4, namely the technical solution involving a hydrogen production system based on the electrolysis of water vapor obtained with concentrated solar thermal systems and electrical power obtained using concentrating photovoltaic systems.

  13. Multi-criteria analysis on how to select solar radiation hydrogen production system

    Science.gov (United States)

    Badea, G.; Naghiu, G. S.; Felseghi, R.-A.; Rǎboacǎ, S.; Aşchilean, I.; Giurca, I.

    2015-12-01

    The purpose of this article is to present a method of selecting hydrogen-production systems using the electric power obtained in photovoltaic systems, and as a selecting method, we suggest the use of the Advanced Multi-Criteria Analysis based on the FRISCO formula. According to the case study on how to select the solar radiation hydrogen production system, the most convenient alternative is the alternative A4, namely the technical solution involving a hydrogen production system based on the electrolysis of water vapor obtained with concentrated solar thermal systems and electrical power obtained using concentrating photovoltaic systems.

  14. Commentary on the Liquid Metallic Hydrogen Model of the Sun III. Insight into Solar Lithium Abundances

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-04-01

    Full Text Available The apparent depletion of lithium represents one of the grea test challenges to modern gaseous solar models. As a result, lithium has been hypothes ized to undergo nuclear burning deep within the Sun. Conversely, extremely low lith ium abundances can be easily accounted for within the liquid metallic hydrogen mo del, as lithium has been hypothesized to greatly stabilize the formation of metalli c hydrogen (E. Zurek et al. A little bit of lithium does a lot for hydrogen. Proc. Nat. Acad. Sci. USA , 2009, v. 106, no. 42, 17640–17643. Hence, the abundances of lithium on th e solar surface can be explained, not by requiring the nuclear burning of this elem ent, but rather, by suggesting that the Sun is retaining lithium within the solar body in ord er to help stabilize its liquid metallic hydrogen lattice. Unlike lithium, many of t he other elements synthesized within the Sun should experience powerful lattice exclusio nary forces as they are driven out of the intercalate regions between the layered liquid me tallic hydrogen hexagonal planes (Robitaille J.C. and Robitaille P.M. Liquid Metalli c Hydrogen III. Intercalation and Lattice Exclusion Versus Gravitational Settling and Th eir Consequences Relative to Internal Structure, Surface Activity, and Solar Winds in the Sun. Progr. Phys ., 2013, v. 2, in press. As for lithium, its stabilizing role within t he solar interior helps to account for the lack of this element on the surface of the Sun.

  15. Improved performance in GaInNAs solar cells by hydrogen passivation

    Science.gov (United States)

    Fukuda, M.; Whiteside, V. R.; Keay, J. C.; Meleco, A.; Sellers, I. R.; Hossain, K.; Golding, T. D.; Leroux, M.; Al Khalfioui, M.

    2015-04-01

    The effect of UV-activated hydrogenation on the performance of GaInNAs solar cells is presented. A proof-of-principle investigation was performed on non-optimum GaInNAs cells, which allowed a clearer investigation of the role of passivation on the intrinsic nitrogen-related defects in these materials. Upon optimized hydrogenation of GaInNAs, a significant reduction in the presence of defect and impurity based luminescence is observed as compared to that of unpassivated reference material. This improvement in the optical properties is directly transferred to an improved performance in solar cell operation, with a more than two-fold improvement in the external quantum efficiency and short circuit current density upon hydrogenation. Temperature dependent photovoltaic measurements indicate a strong contribution of carrier localization and detrapping processes, with non-radiative processes dominating in the reference materials, and evidence for additional strong radiative losses in the hydrogenated solar cells.

  16. Improved performance in GaInNAs solar cells by hydrogen passivation

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, M.; Whiteside, V. R.; Keay, J. C.; Meleco, A.; Sellers, I. R. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, Oklahoma 73019 (United States); Hossain, K.; Golding, T. D. [Amethyst Research Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); Leroux, M.; Al Khalfioui, M. [CRHEA-CNRS, Rue Bernard Gregory, Valbonne 06560 (France)

    2015-04-06

    The effect of UV-activated hydrogenation on the performance of GaInNAs solar cells is presented. A proof-of-principle investigation was performed on non-optimum GaInNAs cells, which allowed a clearer investigation of the role of passivation on the intrinsic nitrogen-related defects in these materials. Upon optimized hydrogenation of GaInNAs, a significant reduction in the presence of defect and impurity based luminescence is observed as compared to that of unpassivated reference material. This improvement in the optical properties is directly transferred to an improved performance in solar cell operation, with a more than two-fold improvement in the external quantum efficiency and short circuit current density upon hydrogenation. Temperature dependent photovoltaic measurements indicate a strong contribution of carrier localization and detrapping processes, with non-radiative processes dominating in the reference materials, and evidence for additional strong radiative losses in the hydrogenated solar cells.

  17. Future production of hydrogen from solar energy and water - A summary and assessment of U.S. developments

    Science.gov (United States)

    Hanson, J. A.; Escher, W. J. D.

    1979-01-01

    The paper examines technologies of hydrogen production. Its delivery, distribution, and end-use systems are reviewed, and a classification of solar energy and hydrogen production methods is suggested. The operation of photoelectric processes, biophotolysis, photocatalysis, photoelectrolysis, and of photovoltaic systems are reviewed, with comments on their possible hydrogen production potential. It is concluded that solar hydrogen derived from wind energy, photovoltaic technology, solar thermal electric technology, and hydropower could supply some of the hydrogen for air transport by the middle of the next century.

  18. Hydrogen as the solar energy translator. [in photochemical and photovoltaic processes

    Science.gov (United States)

    Kelley, J. H.

    1979-01-01

    Many concepts are being investigated to convert sunlight to workable energy forms with emphasis on electricity and thermal energy. The electrical alternatives include direct conversion of photons to electricity via photovoltaic solar cells and solar/thermal production of electricity via heat-energy cycles. Solar cells, when commercialized, are expected to have efficiencies of about 12 to 14 percent. The cells would be active about eight hours per day. However, solar-operated water-splitting process research, initiated through JPL, shows promise for direct production of hydrogen from sunlight with efficiencies of up to 35 to 40 percent. The hydrogen, a valuable commodity in itself, can also serve as a storable energy form, easily and efficiently converted to electricity by fuel cells and other advanced-technology devices on a 24-hour basis or on demand with an overall efficiency of 25 to 30 percent. Thus, hydrogen serves as the fundamental translator of energy from its solar form to electrical form more effectively, and possibly more efficiently, than direct conversion. Hydrogen also can produce other chemical energy forms using solar energy.

  19. Hydrogen as the solar energy translator. [in photochemical and photovoltaic processes

    Science.gov (United States)

    Kelley, J. H.

    1979-01-01

    Many concepts are being investigated to convert sunlight to workable energy forms with emphasis on electricity and thermal energy. The electrical alternatives include direct conversion of photons to electricity via photovoltaic solar cells and solar/thermal production of electricity via heat-energy cycles. Solar cells, when commercialized, are expected to have efficiencies of about 12 to 14 percent. The cells would be active about eight hours per day. However, solar-operated water-splitting process research, initiated through JPL, shows promise for direct production of hydrogen from sunlight with efficiencies of up to 35 to 40 percent. The hydrogen, a valuable commodity in itself, can also serve as a storable energy form, easily and efficiently converted to electricity by fuel cells and other advanced-technology devices on a 24-hour basis or on demand with an overall efficiency of 25 to 30 percent. Thus, hydrogen serves as the fundamental translator of energy from its solar form to electrical form more effectively, and possibly more efficiently, than direct conversion. Hydrogen also can produce other chemical energy forms using solar energy.

  20. Evaluation of the photochemical production of hydrogen from solar energy

    Energy Technology Data Exchange (ETDEWEB)

    Heppert, J. A.

    1977-08-09

    The potential for utilizing solar energy through photochemical storage were investigated. Both water and nitrosyl chloride systems are examined. A comprehensive review of the literature led to the conclusion that many major questions must be answered before photochemical energy storage becomes a viable alternate means of exploiting solar energy.

  1. Calculation of the hydrogen produced by a PEM electrolyzer based on solar radiation in Zacatecas; Estimacion del hidrogeno producido por un electrolizador PEM a partir de la radiacion solar en Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S. M.; Villagrana-Munoz, L.E.; Garcia-Saldivar, V.M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico)]. E-mail: duronsm@prodigy.net.mx; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)

    2009-09-15

    This work presents the calculation of the amount of hydrogen obtained from the use of a proton exchange membrane electrolysis cell. Measurements performed at the solarimeter station of the Campus Siglo XXI at the Zacatecas Autonomous University were used as a basis. Solar radiation was analyzed for the period November 2007 to April 2008, corresponding to when there is less solar radiation. The amount of average irradiation measured was de 6.6 kW-h/ m{sup 2}. The evaluation of the solar-hydrogen system was conducted with linear regressions of the behavior of the hydrogen flow in LN/min versus the solar irradiance in W/m{sup 2} for a PEM electrolyzer. The results obtained indicate that the maximum amount of hydrogen produced occurred in the month of April, with 9LN/min produced with a radiation intensity of roughly 900 W/m{sup 2}; a minimum of 6 LN/min was produced with a radiation of roughly 600 W/m{sup 2} during the month of December. Based on these results, we can foresee a minimum amount of hydrogen generated of 6 to 9 LN/min in the state of Zacatecas during an entire year, since the months evaluated are those with the least solar radiation. The measurements performed by the Siglo XXI station show that the solar radiation power measured is higher than the national and worldwide means, making Zacatecas a strategic state for the use of this renewable energy. The amounts calculated of hydrogen produced would indicate that it is feasible to establish solar-hydrogen systems in this region in order to obtain this energy using PEM electrolyzers. [Spanish] En este trabajo se presenta el calculo de la cantidad de hidrogeno que se obtendria, empleando un electrolizador de membrana de intercambio de protones tipo, tomando como base las medidas realizadas en la Estacion Solarimetrica del Campus Siglo XXI en la Universidad Autonoma de Zacatecas. El analisis de la radiacion solar se realizo en el periodo de noviembre de 2007 a abril de 2008 correspondiendo a la epoca de menor

  2. Simple and Efficient System for Combined Solar Energy Harvesting and Reversible Hydrogen Storage.

    Science.gov (United States)

    Li, Lu; Mu, Xiaoyue; Liu, Wenbo; Mi, Zetian; Li, Chao-Jun

    2015-06-24

    Solar energy harvesting and hydrogen economy are the two most important green energy endeavors for the future. However, a critical hurdle to the latter is how to safely and densely store and transfer hydrogen. Herein, we developed a reversible hydrogen storage system based on low-cost liquid organic cyclic hydrocarbons at room temperature and atmospheric pressure. A facile switch of hydrogen addition (>97% conversion) and release (>99% conversion) with superior capacity of 7.1 H2 wt % can be quickly achieved over a rationally optimized platinum catalyst with high electron density, simply regulated by dark/light conditions. Furthermore, the photodriven dehydrogenation of cyclic alkanes gave an excellent apparent quantum efficiency of 6.0% under visible light illumination (420-600 nm) without any other energy input, which provides an alternative route to artificial photosynthesis for directly harvesting and storing solar energy in the form of chemical fuel.

  3. Hydrogen production with a solar steam–methanol reformer and colloid nanocatalyst

    KAUST Repository

    Lee, Ming-Tsang

    2010-01-01

    In the present study a small steam-methanol reformer with a colloid nanocatalyst is utilized to produce hydrogen. Radiation from a focused continuous green light laser (514 nm wavelength) is used to provide the energy for steam-methanol reforming. Nanocatalyst particles, fabricated by using pulsed laser ablation technology, result in a highly active catalyst with high surface to volume ratio. A small novel reformer fabricated with a borosilicate capillary is employed to increase the local temperature of the reformer and thereby increase hydrogen production. The hydrogen production output efficiency is determined and a value of 5% is achieved. Experiments using concentrated solar simulator light as the radiation source are also carried out. The results show that hydrogen production by solar steam-methanol colloid nanocatalyst reforming is both feasible and promising. © 2009 Professor T. Nejat Veziroglu.

  4. Solar-driven Hydrogen Production by the use of MIEC Membranes : A Techno-Economic Assessment

    OpenAIRE

    Nilsson, Mattias

    2012-01-01

    This thesis comprises an assessment of a novel concept to produce high purity hydrogen using mixed oxide ion/electronic conductor (MIEC) membranes and energy provided by solar concentrators (i.e. parabolic troughs or parabolic dishes). The vision of this concept is that it will be used to produce tons of high purity hydrogen for fuel cells, which is a scarce commodity with an increasing demand from residential and transportation power generation applications. The MIEC membrane activates a ste...

  5. Stable, high-efficiency amorphous silicon solar cells with low hydrogen content

    Energy Technology Data Exchange (ETDEWEB)

    Fortmann, C.M.; Hegedus, S.S. (Institute of Energy Conversion, Newark, DE (United States))

    1992-12-01

    Results and conclusions obtained during a research program of the investigation of amorphous silicon and amorphous silicon based alloy materials and solar cells fabricated by photo-chemical vapor and glow discharge depositions are reported. Investigation of the effects of the hydrogen content in a-si:H i-layers in amorphous silicon solar cells show that cells with lowered hydrogen content i-layers are more stable. A classical thermodynamic formulation of the Staebler-Wronski effect has been developed for standard solar cell operating temperatures and illuminations. Methods have been developed to extract a lumped equivalent circuit from the current voltage characteristic of a single junction solar cell in order to predict its behavior in a multijunction device.

  6. Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals

    KAUST Repository

    Chen, X.

    2011-01-20

    When used as a photocatalyst, titanium dioxide (TiO 2) absorbs only ultraviolet light, and several approaches, including the use of dopants such as nitrogen, have been taken to narrow the band gap of TiO 2. We demonstrated a conceptually different approach to enhancing solar absorption by introducing disorder in the surface layers of nanophase TiO 2 through hydrogenation. We showed that disorder-engineered TiO 2 nanocrystals exhibit substantial solar-driven photocatalytic activities, including the photo-oxidation of organic molecules in water and the production of hydrogen with the use of a sacrificial reagent.

  7. Enhanced Photovoltaic Properties of the Solar Cells Based on Cosensitization of CdS and Hydrogenation

    Directory of Open Access Journals (Sweden)

    Hongcai He

    2015-01-01

    Full Text Available The hydrogenated TiO2 porous nanocrystalline film is modified with CdS quantum dots by successive ionic layer adsorption and reaction (SILAR method to prepare the cosensitized TiO2 solar cells by CdS quantum dots and hydrogenation. The structure and topography of the composite photoanode film were confirmed by X-ray diffraction and scanning electron microscopy. With deposited CdS nanoparticles, UV absorption spectra of H:TiO2 photoanode film indicated a considerably enhanced absorption in the visible region. The cosensitized TiO2 solar cell by CdS quantum dots and hydrogenation presents much better photovoltaic properties than either CdS sensitized TiO2 solar cells or hydrogenated TiO2 solar cells, which displays enhanced photovoltaic performance with power conversion efficiency (η of 1.99% (Jsc=6.26 mA cm−2, Voc=0.65 V, and FF = 0.49 under full one-sun illumination. The reason for the enhanced photovoltaic performance of the novel cosensitized solar cell is primarily explained by studying the Nyquist spectrums, IPCE spectra, dark current, and photovoltaic performances.

  8. Nanocatalysts for Solar Water Splitting and a Perspective on Hydrogen Economy.

    Science.gov (United States)

    Grewe, Tobias; Meggouh, Mariem; Tüysüz, Harun

    2016-01-01

    In this review article, nanocatalysts for solar hydrogen production are the focus of discussion as they can contribute to the development of sustainable hydrogen production in order to meet future energy demands. Achieving this task is subject of scientific aspirations in the field of photo- and photoelectrocatalysis for solar water splitting where systems of single catalysts or tandem configurations are being investigated. In search of a suitable catalyst, a number of crucial parameters are laid out which need to be considered for material design, in particular for nanostructured materials that provide exceptional physical and chemical properties in comparison to their bulk counterparts. Apart from synthetic approaches for nanocatalysts, key parameters and properties of nanostructured photocatalysts such as light absorption, charge carrier generation, charge transport, separation and recombination, and other events that affect nanoscale catalysts are discussed. To provide a deeper understanding of these key parameters and properties, their contribution towards existing catalyst systems is evaluated for photo- and photoelectrocatalytic solar hydrogen evolution. Finally, an insight into hydrogen production processes is given, stressing the current development of sustainable hydrogen sources and presenting a perspective towards a hydrogen-based economy.

  9. Hydrogen and oxygen from water. Part 6: Quenching the effluent from a solar furnace

    Science.gov (United States)

    Diver, R. B.; Pederson, S.; Kappauf, T.; Fletcher, E. A.

    1983-04-01

    Numerical integration of a set of rate equations applicable to the hydrogen-oxygen system suggests that it should be possible to recover H2 and O2 by rapid cooling of low-pressure equilibrium mixtures from a solar furnace. Using the University of Minnesota 4.2 m solar furnace, we were able to recover explosive mixtures of H2 and O2 from water which had been heated to about 2100K. The numerical calculations and the experiment are described.

  10. A noie on the loss of hydrogen and the supply of hydrogen to the Earth as a direct or indirect effect of the solar wind

    Directory of Open Access Journals (Sweden)

    N. A. BARRICELLI

    1969-06-01

    Full Text Available The rate at which hydrogen is supplied to the Earth
    by the solar wind, and the rate at which hydrogen escapes from the Earth
    by diffusion into space are compared 011 the basis of recent estimates. It
    is found that the hydrogen supplied by the solar wind is roughly comparable
    to or may even be larger than present hydrogen losses. The Earth
    may have lost most of its hydrogen at an early stage when, according to
    Urey and Miller (1959, Pox (1960 and others, the Earth had a reducing,
    instead of an oxidizing atmosphere. However, no sufficient evidence is
    yet available to determine whether the Earth is still losing more hydrogen
    than it receives. The common notion that the Earth is still in the process
    of losing its hydrogen is therefore in question.

  11. Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-01-01

    Full Text Available The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature (TL on Gibbs free energy related to the H2 production step were examined in detail. The cycle (ηcycle and solar-to-fuel energy conversion (ηsolar-to-fuel efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that ηcycle and ηsolar-to-fuel increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (TH. It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At TH=2280 K, by applying 60% heat recuperation, maximum ηcycle of 39.0% and ηsolar-to-fuel of 47.1% for the Tb-WS cycle can be attained.

  12. Amorphous Hydrogenated Carbon-Nitrogen Alloy Thin Films for Solar Cell Application

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-Bin; DING Zheng-Ming; PANG Qian-Jun; CUI Rong-Qiang

    2001-01-01

    Amorphous hydrogenated carbon-nitrogen alloy (a-CNx :H) thin films have been deposited on silicon substratesby improved dc magnetron sputtering from a graphite target in nitrogen and hydrogen gas discharging. Thefilms are investigated by using Raman spectroscopy, x-ray photoelectron spectroscopy, spectral ellipsometer and electron spin resonance techniques. The optimized process condition for solar cell application is discussed. Thephotovoltaic property of a-CNx:H/silicon heterojunctions can be improved by the adjustment of the pressureratio of hydrogen to nitrogen and unbalanced magnetic field intensity. Open-circuit voltage and short-circuitcurrent reach 300mV and 5.52 Ma/cm2, respectively.

  13. Photobiological production of hydrogen: a solar energy conversion option

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.; Lien, S.; Seibert, M.

    1979-01-01

    This literature survey of photobiological hydrogen production covers the period from its discovery in relatively pure cultures during the early 1930s to the present. The focus is hydrogen production by phototrophic organisms (and their components) which occurs at the expense of light energy and electron-donating substrates. The survey covers the major contributions in the area; however, in many cases, space has limited the degree of detail provided. Among the topics included is a brief historical overview of hydrogen metabolism in photosynthetic bacteria, eucaryotic algae, and cyanobacteria (blue--green algae). The primary enzyme systems, including hydrogenase and nitrogenase, are discussed along with the manner in which they are coupled to electron transport and the primary photochemistry of photosynthesis. A number of in vivo and in vitro photobiological hydrogen evolving schemes including photosynthetic bacterial, green algal, cyanobacterial, two-stage, and cell-free systems are examined in some detail. The remainder of the review discusses specific technical problem areas that currently limit the yield and duration of many of the systems and research that might lead to progress in these specific areas. The final section outlines, in broadest terms, future research directions necessary to develop practical photobiological hydrogen-producing systems. Both whole cell (near- to mid-term) and cell-free (long-term) systems should be emphasized. Photosynthetic bacteria currently show the most promise for near-term applied systems.

  14. Possibly scalable solar hydrogen generation with quasi-artificial leaf approach

    OpenAIRE

    Patra, Kshirodra Kumar; Bhuskute, Bela D.; Chinnakonda S. Gopinath

    2017-01-01

    Any solar energy harvesting technology must provide a net positive energy balance, and artificial leaf concept provided a platform for solar water splitting (SWS) towards that. However, device stability, high photocurrent generation, and scalability are the major challenges. A wireless device based on quasi-artificial leaf concept (QuAL), comprising Au on porous TiO2 electrode sensitized by PbS and CdS quantum dots (QD), was demonstrated to show sustainable solar hydrogen (490???25??mol/h (co...

  15. Extremely high reflection of solar wind protons as neutral hydrogen atoms from regolith in space

    CERN Document Server

    Wieser, Martin; Futaana, Yoshifumi; Holmström, Mats; Bhardwaj, Anil; Sridharan, R; Dhanya, MB; Wurz, Peter; Schaufelberger, Audrey; Asamura, Kazushi; 10.1016/j.pss.2009.09.012

    2010-01-01

    We report on measurements of extremely high reflection rates of solar wind particles from regolith-covered lunar surfaces. Measurements by the Sub-keV Atom Reflecting Analyzer (SARA) instrument on the Indian Chandrayaan-1 spacecraft in orbit around the Moon show that up to 20% of the impinging solar wind protons are reflected from the lunar surface back to space as neutral hydrogen atoms. This finding, generally applicable to regolith-covered atmosphereless bodies, invalidates the widely accepted assumption that regolith almost completely absorbs the impinging solar wind.

  16. Autonomous system for wireless network communication powered by photovoltaic solar energy; Sistema autonomo de comunicacao sem fio em malha alimentado por energia solar fotovoltaica

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Rafael Herrero

    2009-07-01

    The wireless mesh network communication technology, based on the IEEE802.11 standard, has been a relevant technology solution for wireless networking in the recent years. However, even with the elimination of cables for data communication, the wireless mesh networks have to be connected to a voltage source using an electrical cable that may not be available at the local installation. In this scenario, being Brazil a country located in a tropical zone that receives large annual solar irradiation, the conversion of photons to electricity can be an alternative to eliminate the needs of wiring to the mesh access points. This work contributes to the development of autonomous wireless mesh communication systems powered by solar energy, with easy installation in urban or rural areas. This work also describes its evaluations in aspects such as autonomy, wireless coverage, number of users supported, installation height and throughput. (author)

  17. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  18. Hydrogenated Silicon Layers and Solar Cells Deposited at Very Low Substrate Temperature

    NARCIS (Netherlands)

    Bronsveld, P.C.P.

    2013-01-01

    For direct production of solar cells on cheap plastics, the quality of VHF-PECVD deposited intrinsic and doped silicon layers made at substrate temperatures ≤ 100 °C was optimized. The investigation showed that at lower substrate temperatures, higher hydrogen dilution of the source gas silane was re

  19. Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere

    NARCIS (Netherlands)

    Leenaarts, J.; Carlsson, M.; Hansteen, V.; Rutten, R.J.

    2007-01-01

    Context: The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of magneto-acoustic shocks. Since the pressure, temperature, and

  20. Thermal ideality factor of hydrogenated amorphous silicon p-i-n solar cells

    NARCIS (Netherlands)

    Kind, R.; Van Swaaij, R.A.C.M.M.; Rubinelli, F.A.; Solntsev, S.; Zeman, M.

    2011-01-01

    The performance of hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells is limited, as they contain a relatively high concentration of defects. The dark current voltage (JV) characteristics at low forward voltages of these devices are dominated by recombination processes. The recombination rate

  1. Efficient solar hydrogen production by photocatalytic water splitting: From fundamental study to pilot demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Dengwei; Guo, Liejin; Zhao, Liang; Zhang, Ximin; Liu, Huan; Li, Mingtao; Shen, Shaohua; Liu, Guanjie; Hu, Xiaowei; Zhang, Xianghui; Zhang, Kai; Ma, Lijin; Guo, Penghui [State Key Lab of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, 28 Xianning West Road, Xi' an 710049 (China)

    2010-07-15

    Photocatalytic water splitting with solar light is one of the most promising technologies for solar hydrogen production. From a systematic point of view, whether it is photocatalyst and reaction system development or the reactor-related design, the essentials could be summarized as: photon transfer limitations and mass transfer limitations (in the case of liquid phase reactions). Optimization of these two issues are therefore given special attention throughout our study. In this review, the state of the art for the research of photocatalytic hydrogen production, both outcomes and challenges in this field, were briefly reviewed. Research progress of our lab, from fundamental study of photocatalyst preparation to reactor configuration and pilot level demonstration, were introduced, showing the complete process of our effort for this technology to be economic viable in the near future. Our systematic and continuous study in this field lead to the development of a Compound Parabolic Concentrator (CPC) based photocatalytic hydrogen production solar rector for the first time. We have demonstrated the feasibility for efficient photocatalytic hydrogen production under direct solar light. The exiting challenges and difficulties for this technology to proceed from successful laboratory photocatalysis set-up up to an industrially relevant scale are also proposed. These issues have been the object of our research and would also be the direction of our study in future. (author)

  2. Integrating Wind And Solar With Hydrogen Producing Fuel Cells

    NARCIS (Netherlands)

    Hemmes, K.

    2007-01-01

    The often proposed solution for the fluctuating wind energy supply is the conversion of the surplus of wind energy into hydrogen by means of electrolysis. In this paper a patented alternative is proposed consisting of the integration of wind turbines with internal reforming fuel-cells, capable of

  3. Integrating Wind And Solar With Hydrogen Producing Fuel Cells

    NARCIS (Netherlands)

    Hemmes, K.

    2007-01-01

    The often proposed solution for the fluctuating wind energy supply is the conversion of the surplus of wind energy into hydrogen by means of electrolysis. In this paper a patented alternative is proposed consisting of the integration of wind turbines with internal reforming fuel-cells, capable of co

  4. Solar chemistry / hydrogen - Summary report on the research programme 2002; Forschungsprogramm Solarchemie / Wasserstoff

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This summary report for the Swiss Federal Office of Energy (SFOE) on the solar chemistry / hydrogen research programme presents an overview of work done in these fields in Switzerland in 2002. It includes an overview of work done on 12 research and development projects and 9 pilot and demonstration projects. The volume is completed with a selection of 13 annual reports on particular topics, including transformation and storage of energy by photo-chemical, photo-electrochemical and photovoltaic means, generation of hydrogen using water splitting, solar production of zinc and calcium, catalytic synthesis, redox processes for the production of hydrogen and compressed air as a means of storing energy. Also covered are the topics of how solar chemistry can help reduce CO{sub 2} emissions and the management of the International Energy Agency's hydrogen annex 14. Further reports look at the destabilisation of metal hydride compounds, materials for sustainable energy technologies and diffusion barriers for high-pressure hydrogen tanks.

  5. Systems of solar hydrogen storage; Sistemas de almacenamiento de hidrogeno solar

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, E.; Isorna, F.; Rosa, F.

    2004-07-01

    Hydrogen has the potential to play a major role in a future energy system. Hydrogen production from renewable energy can solve some of the associated problems to such energies. From production to end-users, it is essential the development of suitable hydrogen delivery and storage systems, taking into consideration the particular characteristics of each project. This article describes, in a general way, main choices for hydrogen storage when produced from renewable energy, and shows the particular case of the INTA's Hydrogen Production Plant. (Author)

  6. Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure.

    Science.gov (United States)

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

    2015-09-15

    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 utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

  7. Solar-Driven Hydrogen Peroxide Production Using Polymer-Supported Carbon Dots as Heterogeneous Catalyst

    Science.gov (United States)

    Gogoi, Satyabrat; Karak, Niranjan

    2017-10-01

    Safe, sustainable, and green production of hydrogen peroxide is an exciting proposition due to the role of hydrogen peroxide as a green oxidant and energy carrier for fuel cells. The current work reports the development of carbon dot-impregnated waterborne hyperbranched polyurethane as a heterogeneous photo-catalyst for solar-driven production of hydrogen peroxide. The results reveal that the carbon dots possess a suitable band-gap of 2.98 eV, which facilitates effective splitting of both water and ethanol under solar irradiation. Inclusion of the carbon dots within the eco-friendly polymeric material ensures their catalytic activity and also provides a facile route for easy catalyst separation, especially from a solubilizing medium. The overall process was performed in accordance with the principles of green chemistry using bio-based precursors and aqueous medium. This work highlights the potential of carbon dots as an effective photo-catalyst.

  8. Light induced electrical and macroscopic changes in hydrogenated polymorphous silicon solar cells

    Science.gov (United States)

    Kim, K. H.; Johnson, E. V.; Abramov, A.; Cabarrocas, P. Roca i.

    2012-07-01

    We report on light-induced electrical and macroscopic changes in hydrogenated polymorphous silicon (pm-Si:H) PIN solar cells. To explain the particular light-soaking behavior of such cells - namely an increase of the open circuit voltage (Voc) and a rapid drop of the short circuit current density (Jsc) - we correlate these effects to changes in hydrogen incorporation and structural properties in the layers of the cells. Numerous techniques such as current-voltage characteristics, infrared spectroscopy, hydrogen exodiffusion, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and spectroscopic ellipsometry are used to study the light-induced changes from microscopic to macroscopic scales (up to tens of microns). Such comprehensive use of complementary techniques lead us to suggest that light-soaking produces the diffusion of molecular hydrogen, hydrogen accumulation at p-layer/substrate interface and localized delamination of the interface. Based on these results we propose that light-induced degradation of PIN solar cells has to be addressed from not only as a material issue, but also a device point of view. In particular we bring experimental evidence that localized delamination at the interface between the p-layer and SnO2 substrate by light-induced hydrogen motion causes the rapid drop of Jsc.

  9. Light induced electrical and macroscopic changes in hydrogenated polymorphous silicon solar cells

    Directory of Open Access Journals (Sweden)

    Roca i Cabarrocas P.

    2012-07-01

    Full Text Available We report on light-induced electrical and macroscopic changes in hydrogenated polymorphous silicon (pm-Si:H PIN solar cells. To explain the particular light-soaking behavior of such cells – namely an increase of the open circuit voltage (Voc and a rapid drop of the short circuit current density (Jsc – we correlate these effects to changes in hydrogen incorporation and structural properties in the layers of the cells. Numerous techniques such as current-voltage characteristics, infrared spectroscopy, hydrogen exodiffusion, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and spectroscopic ellipsometry are used to study the light-induced changes from microscopic to macroscopic scales (up to tens of microns. Such comprehensive use of complementary techniques lead us to suggest that light-soaking produces the diffusion of molecular hydrogen, hydrogen accumulation at p-layer/substrate interface and localized delamination of the interface. Based on these results we propose that light-induced degradation of PIN solar cells has to be addressed from not only as a material issue, but also a device point of view. In particular we bring experimental evidence that localized delamination at the interface between the p-layer and SnO2 substrate by light-induced hydrogen motion causes the rapid drop of Jsc.

  10. Solar hydrogen energy pilot project for Libya, SHEPL

    Energy Technology Data Exchange (ETDEWEB)

    Gibril S Eljrushi [Faculty of Engineering, University of 7th October, Misurata, (Libyan Arab Jamahiriya); Madani A Dakhil [Faculty of Science, Al-Fateh University, Tripoli, (Libyan Arab Jamahiriya); Mohammed F Aldrini [G. S., Faculty of Engineering, University of 7th October, Misurata, (Libyan Arab Jamahiriya)

    2006-07-01

    This work presents the first stage of the SHEPL project which includes technical and economic analysis of the main project components. These are Photovoltaics power generation of one MW, electrolysis plant for hydrogen production, fuel cells power plant to generate electricity at night time, sea water desalination plant, and other required facilities. The project is intended to supply a small community of twenty families with all its energy and water requirements, to be completely independent from local utilities. (authors)

  11. Estimation of the hydrogen flux from a PEM electrolyzer, based in the solar irradiation measured in Zacatecas Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Villagrana-Munoz, L.E.; Garcia-Saldivar, V.M.; Escalante-Garcia, I.L. [Univ. Autonoma de Zacatecas, Zacatecas (Mexico). Unidad Academica de Ciencias Quimicas; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo (Mexico)

    2010-07-15

    The current cost of obtaining hydrogen from electrolyzers is higher than the cost of producing fossil fuels. However, with advances in technology and greater use of alternative energy sources, the cost of electrolytic hydrogen production may decrease to the point of being competitive. This study calculated how much hydrogen can be produced in a typical polymer exchange membrane (PEM) electrolyzer. Local solar irradiation measurements were carried out from November 2007 to April 2008 at the Campus Siglo 21 Solarimetric Station at Zacatecas University in Mexico. The mean irradiation measured was 6.6 kW-h per m{sup 2}. Based on the solar data obtained at the station, the hydrogen produced by a typical solar-hydrogen (SH) system was evaluated. The study showed that an important quantity of hydrogen as an energy vector could be obtained from solar radiation. April was determined to be the month of maximum hydrogen production. The lowest hydrogen production was in November. The data obtained during this study can be used to evaluate the solar renewable energy resource expressed as hydrogen production. 19 refs., 1 tab., 4 figs.

  12. Hydrogen production by hydrogen sulfide splitting using concentrated solar energy - Thermodynamics and economic evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Villasmil, W. [Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland); Steinfeld, A. [Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland); Solar Technology Laboratory, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2010-11-15

    Thermodynamic and economic analyses were carried out to evaluate the use of concentrated solar energy for driving the endothermic dissociation reaction H{sub 2}S {yields} H{sub 2} + 0.5S{sub 2}. Three different schemes were assessed: (1) a pure solar process; (2) a hybrid process, which uses both solar and natural gas combustion as the energy sources of high-temperature process heat; and (3) the Claus process. This study indicates that the pure solar process has the potential of lowering the disposal costs of H{sub 2}S vis-a-vis the conventional Claus process while co-producing H{sub 2} without concomitant CO{sub 2} emissions. An economic assessment for a 40 MWth chemical plant using solar tower technology indicates savings of approximately 45% in comparison to the Claus process. Solar H{sub 2} production is estimated at a cost in the range of 0.061-0.086 $/kW h, based on its lower heating value and without credit attributed to H{sub 2}S disposal. A sensitivity analysis revealed that the quench efficiency represents the parameter with the highest impact on the economics of the process. A hybrid natural gas/solar plant design able to operate 24 h-a-day is predicted to reduce the H{sub 2} production cost to 0.058 $/kW h at current fuel prices, however, at the expense of increased complexity related with the hybrid reactor design and operation plus the associated CO{sub 2} emissions of 0.42 kg/kW h. (author)

  13. 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.

  14. Economic comparison of solar hydrogen generation by means of thermochemical cycles and electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Graf, D.; Monnerie, N.; Roeb, M.; Schmitz, M.; Sattler, C. [German Aerospace Center, Institute of Technical Thermodynamics, Solar Research, Linder Hoehe, 51147 Cologne (Germany)

    2008-09-15

    Hydrogen is acclaimed to be an energy carrier of the future. Currently, it is mainly produced by fossil fuels, which release climate-changing emissions. Thermochemical cycles, represented here by the hybrid-sulfur cycle and a metal oxide based cycle, along with electrolysis of water are the most promising processes for 'clean' hydrogen mass production for the future. For this comparison study, both thermochemical cycles are operated by concentrated solar thermal power for multistage water splitting. The electricity required for the electrolysis is produced by a parabolic trough power plant. For each process investment, operating and hydrogen production costs were calculated on a 50 MW{sub th} scale. The goal is to point out the potential of sustainable hydrogen production using solar energy and thermochemical cycles compared to commercial electrolysis. A sensitivity analysis was carried out for three different cost scenarios. As a result, hydrogen production costs ranging from 3.9-5.6 EUR/kg for the hybrid-sulfur cycle, 3.5-12.8 EUR/kg for the metal oxide based cycle and 2.1-6.8 EUR/kg for electrolysis were obtained. (author)

  15. Hot wire deposited hydrogenated amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mahan, A.H.; Iwaniczko, E.; Nelson, B.P.; Reedy, R.C. Jr.; Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    This paper details the results of a study in which low H content, high deposition rate hot wire (HW) deposited amorphous silicon (a-Si:H) has been incorporated into a substrate solar cell. The authors find that the treatment of the top surface of the HW i layer while it is being cooled from its high deposition temperature is crucial to device performance. They present data concerning these surface treatments, and correlate these treatments with Schottky device performance. The authors also present first generation HW n-i-p solar cell efficiency data, where a glow discharge (GD) {mu}c-Si(p) layer was added to complete the partial devices. No light trapping layer was used to increase the device Jsc. Their preliminary investigations have yielded efficiencies of up to 6.8% for a cell with a 4000 {Angstrom} thick HW i-layer, which degrade less than 10% after a 900 hour light soak. The authors suggest avenues for further improvement of their devices.

  16. STEREO Observations of Energetic Neutral Hydrogen Atoms during the 5 December 2006 Solar Flare

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Davis, A. J.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We report the discovery of energetic neutral hydrogen atoms emitted during the X9 solar event of December 5, 2006. Beginning 1 hour following the onset of this E79 flare, the Low Energy Telescopes (LETs) on both the STEREO A and B spacecraft observed a sudden burst of 1.6 to 15 MeV protons beginning hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within 10 of the Sun, consistent with the measurement resolution. The derived emission profile at the Sun had onset and peak times remarkably similar to the GOES soft X-ray profile and continued for more than an hour. The observed arrival directions and energy spectrum argue strongly that the particle events less than 5 MeV were due to energetic neutral hydrogen atoms (ENAs). To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. Possible origins for the production of ENAs in a large solar event are considered. We conclude that the observed ENAs were most likely produced in the high corona and that charge-transfer reactions between accelerated protons and partially-stripped coronal ions are an important source of ENAs in solar events.

  17. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  18. Hydrogen based energy storage for solar energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Vanhanen, J.; Hagstroem, M.; Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland). Advanced Energy Systems

    1998-10-01

    The main technical constraint in solar energy systems which operate around the year is the lack of suitable long-term energy storage. Conventional solutions to overcome the problem of seasonal storage in PV power systems are to use oversized batteries as a seasonal energy storage, or to use a diesel back-up generator. However, affordable lead-acid batteries are not very suitable for seasonal energy storage because of a high self-discharge rate and enhanced deterioration and divergence of the single cells during prolonged periods of low state of charge in times of low irradiation. These disadvantages can be avoided by a back-up system, e.g. a diesel generator, which car supply energy to the loads and charge the battery to the full state of charge to avoid the above mentioned disadvantages. Unfortunately, diesel generators have several disadvantages, e.g. poor starting reliability, frequent need for maintenance and noise

  19. Wiring photosystem I for direct solar hydrogen production.

    Science.gov (United States)

    Lubner, Carolyn E; Grimme, Rebecca; Bryant, Donald A; Golbeck, John H

    2010-01-26

    The generation of H(2) by the use of solar energy is a promising way to supply humankind's energy needs while simultaneously mitigating environmental concerns that arise due to climate change. The challenge is to find a way to connect a photochemical module that harnesses the sun's energy to a catalytic module that generates H(2) with high quantum yields and rates. In this review, we describe a technology that employs a "molecular wire" to connect a terminal [4Fe-4S] cluster of Photosystem I directly to a catalyst, which can be either a Pt nanoparticle or the distal [4Fe-4S] cluster of an [FeFe]- or [NiFe]-hydrogenase enzyme. The keys to connecting these two moieties are surface-located cysteine residues, which serve as ligands to Fe-S clusters and which can be changed through site-specific mutagenesis to glycine residues, and the use of a molecular wire terminated in sulfhydryl groups to connect the two modules. The sulfhydryl groups at the end of the molecular wire form a direct chemical linkage to a suitable catalyst or can chemically rescue a [4Fe-4S] cluster, thereby generating a strong coordination bond. Specifically, the molecular wire can connect the F(B) iron-sulfur cluster of Photosystem I either to a Pt nanoparticle or, by using the same type of genetic modification, to the differentiated iron atom of the distal [4Fe-4S].(Cys)(3)(Gly) cluster of hydrogenase. When electrons are supplied by a sacrificial donor, this technology forms the cathode of a photochemical half-cell that evolves H(2) when illuminated. If such a device were connected to the anode of a photochemical half-cell that oxidizes water, an in vitro solar energy converter could be realized that generates only O(2) and H(2) in the light. A similar methodology can be used to connect Photosystem I to other redox proteins that have surface-located [4Fe-4S] clusters. The controlled light-driven production of strong reductants by such systems can be used to produce other biofuels or to provide

  20. Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

    Science.gov (United States)

    Young, James L.; Steiner, Myles A.; Döscher, Henning; France, Ryan M.; Turner, John A.; Deutsch, Todd G.

    2017-03-01

    Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-doped photocathodes by using a buried p-n junction. Advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.

  1. Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

    Energy Technology Data Exchange (ETDEWEB)

    Young, James L.; Steiner, Myles A.; Döscher, Henning; France, Ryan M.; Turner, John A.; Deutsch, Todd G.

    2017-03-13

    Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-doped photocathodes by using a buried p-n junction. Advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.

  2. Local Interstellar Hydrogen's Disappearance at 1 Au: Four Years of IBEX in the Rising Solar Cycle

    CERN Document Server

    Saul, Lukas; Fuselier, Stephen; Kubiak, Marzena; McComas, Dave; Möbius, Eberhard; Sokół, Justina; Rodríguez, Diego; Scheer, Juergen; Wurz, Peter

    2013-01-01

    NASA's Interstellar Boundary Explorer (IBEX) mission has recently opened a new window on the interstellar medium (ISM) by imaging neutral atoms. One "bright" feature in the sky is the interstellar wind flowing into the solar system. Composed of remnants of stellar explosions as well as primordial gas and plasma, the ISM is by no means uniform. The interaction of the local ISM with the solar wind shapes our heliospheric environment with hydrogen being the dominant component of the very local ISM. In this paper, we report on direct sampling of the neutral hydrogen of the local ISM over four years of IBEX observations. The hydrogen wind observed at 1 AU has decreased and nearly disappeared as the solar activity has increased over the last four years; the signal at 1 AU has dropped off in 2012 by a factor of ~8 to near background levels. The longitudinal offset has also increased with time presumably due to greater radiation pressure deflecting the interstellar wind. We present longitudinal and latitudinal arriva...

  3. Hydrogen passivation of electrically active defects in crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Milstein, J B; Tsuo, Y S; Osterwald, C R; White, C W

    1984-06-01

    We have observed significant improvements in the efficiencies of dendritic web and edge-supported-pulling (ESP) silicon sheet solar cells after hydrogen ion beam passivation for a period of ten minutes or less. We have studied the effects of the hydrogen ion beam treatment with respect to silicon material damage, silicon sputter rate, introduction of impurities, and changes in reflectance. We have determined that the silicon sputter rate for a constant ion beam flux of 0.60 +- 0.05 mA/cm/sup 2/ exhibits a maximum at approximately 1400 eV ion beam energy. We have observed that hydrogen ion beam treatment can result in a reduced fill factor, which is caused by damage to the front metallization of the cell rather than by damage to the p-n junction.

  4. Thermochemical cycles based on metal oxides for solar hydrogen production; Ciclos termoquimicos basados en oxidos metalicos para produccion de hidrogeno solar

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Saavedra, R.; Quejido Cabezas, J.

    2012-11-01

    The growing demand for energy requires the development and optimization of alternative energy sources. One of the options currently being investigated is solar hydrogen production with thermochemical cycles. This process involves the use of concentrated solar radiation as an energy source to dissociate water through a series of endothermic and exothermic chemical reactions, for the purpose of obtaining hydrogen on a sustainable basis. Of all the thermochemical cycles that have been evaluated, the most suitable ones for implementation with solar energy are those based on metal oxides. (Author) 20 refs.

  5. Possibly scalable solar hydrogen generation with quasi-artificial leaf approach.

    Science.gov (United States)

    Patra, Kshirodra Kumar; Bhuskute, Bela D; Gopinath, Chinnakonda S

    2017-07-26

    Any solar energy harvesting technology must provide a net positive energy balance, and artificial leaf concept provided a platform for solar water splitting (SWS) towards that. However, device stability, high photocurrent generation, and scalability are the major challenges. A wireless device based on quasi-artificial leaf concept (QuAL), comprising Au on porous TiO2 electrode sensitized by PbS and CdS quantum dots (QD), was demonstrated to show sustainable solar hydrogen (490 ± 25 µmol/h (corresponds to 12 ml H2 h(-1)) from ~2 mg of photoanode material coated over 1 cm(2) area with aqueous hole (S(2-)/SO3(2-)) scavenger. A linear extrapolation of the above results could lead to hydrogen production of 6 L/h.g over an area of ~23 × 23 cm(2). Under one sun conditions, 4.3 mA/cm(2) photocurrent generation, 5.6% power conversion efficiency, and spontaneous H2 generation were observed at no applied potential (see S1). A direct coupling of all components within themselves enhances the light absorption in the entire visible and NIR region and charge utilization. Thin film approach, as in DSSC, combined with porous titania enables networking of all the components of the device, and efficiently converts solar to chemical energy in a sustainable manner.

  6. Solar Hydrogen Production by Amorphous Silicon Photocathodes Coated with a Magnetron Sputter Deposited Mo2C Catalyst.

    Science.gov (United States)

    Morales-Guio, Carlos G; Thorwarth, Kerstin; Niesen, Bjoern; Liardet, Laurent; Patscheider, Jörg; Ballif, Christophe; Hu, Xile

    2015-06-10

    Coupling of Earth-abundant hydrogen evolution catalysts to photoabsorbers is crucial for the production of hydrogen fuel using sunlight. In this work, we demonstrate the use of magnetron sputtering to deposit Mo2C as an efficient hydrogen evolution reaction catalyst onto surface-protected amorphous silicon (a-Si) photoabsorbers. The a-Si/Mo2C photocathode evolves hydrogen under simulated solar illumination in strongly acidic and alkaline electrolytes. Onsets of photocurrents are observed at potentials as positive as 0.85 V vs RHE. Under AM 1.5G (1 sun) illumination, the photocathodes reach current densities of -11.2 mA cm(-2) at the reversible hydrogen potential in 0.1 M H2SO4 and 1.0 M KOH. The high photovoltage and low-cost of the Mo2C/a-Si assembly make it a promising photocathode for solar hydrogen production.

  7. Research on the optimum hydrogenated silicon thin films for application in solar cells

    Institute of Scientific and Technical Information of China (English)

    Lei Qing-Song; Wu Zhi-Meng; Geng Xin-Hua; Zhao Ying; Sun Jian; Xi Jian-Ping

    2006-01-01

    Hydrogenated silicon (Si:H) thin films for application in solar cells were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 ℃. The electrical,structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage (Ⅰ - Ⅴ) characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

  8. Hydrogen-treated commercial WO3 as an efficient electrocatalyst for triiodide reduction in dye-sensitized solar cells.

    Science.gov (United States)

    Cheng, Ling; Hou, Yu; Zhang, Bo; Yang, Shuang; Guo, Jian Wei; Wu, Long; Yang, Hua Gui

    2013-07-07

    The electrocatalytically inactive commercial WO3 can be transformed into an efficient counter electrode (CE) material for dye-sensitized solar cells (DSCs) via facile hydrogen treatment. The energy conversion efficiency of the DSCs with the hydrogen-treated WO3 CE was 5.43%, while the corresponding value for commercial WO3 with the stoichiometric surface was only 0.63%.

  9. Hydrogen production by Rhodobacter sphaeroides O.U.001 in a flat plate solar bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Eroglu, Inci; Tabanoglu, Altan; Eroglu, Ela [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey); Guenduez, Ufuk; Yuecel, Meral [Department of Biology, Middle East Technical University, 06531 Ankara (Turkey)

    2008-01-15

    Rhodobacter sphaeroides O.U.001 can produce hydrogen under anaerobic conditions and illumination. The objective of this study was to investigate the performance of an 8 l flat plate solar bioreactor operating in outdoor conditions. Different organic acids were used as carbon sources (malate, lactate and acetate) and olive mill waste water was used as a sole substrate source. The consumption and the production of the organic acids were determined by HPLC. The accumulation of by-products, such as poly-{beta}-hydroxybutyrate (PHB) and carotenoid, throughout the course of hydrogen production was determined. The hydrogen production rate was highest (0.01 l/l/h) when malate was the carbon source. Formate was observed as the fermentation end product. Acetate resulted in low hydrogen gas production and high PHB accumulation. When acetate was used as the carbon source, butyrate was produced as a result of fermentation. Promising amounts of PHB and caretenoid were accumulated during hydrogen production from diluted olive mill wastewater. (author)

  10. Commentary on the Liquid Metallic Hydrogen Model of the Sun: Insight Relative to Coronal Holes, Sunspots, and Solar Activity

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-04-01

    Full Text Available While mankind will always remain unable to sample the interior of the Sun, the presence of sunspots and coronal holes can provide clues as to its subsurface structure. Insight relative to the solar body can also be gained by recognizing that the Sun must exist in the condensed state and support a discrete lattice structure, as required for the production of its continuous spectrum. In this regard, the layered liquid metallic hydrogen lattice advanced as a condensed model of the Sun (Robitaille P.M. Liquid Metallic Hydrogen: A Building Block for the Liquid Sun. Progr. Phys ., 2011, v. 3, 60–74; Robitaille P.M. Liquid Metallic Hydrogen II: A Critical Assessment of Current and Primordial Helium Levels in Sun. Progr. Phys ., 2013, v. 2, 35–47; Robitaille J.C. and Robitaille P.M. Liquid Metallic Hydrogen III. Intercalation and Lattice Exclusion Versus Gravitational Settling and Their Consequences Relative to Internal Structure, Surface Activity, and Solar Winds in the Sun. Progr. Phys ., 2013, v. 2, in press provides the ability to add structure to the solar interior. This constitutes a significant advantage over the gaseous solar models. In fact, a layered liquid metallic hydrogen lattice and the associated intercalation of non-hydrogen elements can help to account for the position of sunspots and coronal holes. At the same time, this model provides a greater understanding of the mechanisms which drive solar winds and activity.

  11. Application of metal nanowire networks on hydrogenated amorphous silicon thin film solar cells

    Science.gov (United States)

    Xie, Shouyi; Hou, Guofu; Chen, Peizhuan; Jia, Baohua; Gu, Min

    2017-02-01

    We demonstrate the application of metal nanowire (NW) networks as a transparent electrode on hydrogenated amorphous Si (a-Si:H) solar cells. We first systematically investigate the optical performances of the metal NW networks on a-Si:H solar cells in different electrode configurations through numerical simulations to fully understand the mechanisms to guide the experiments. The theoretically optimized configuration is discovered to be metal NWs sandwiched between a 40 nm indium tin oxide (ITO) layer and a 20 nm ITO layer. The overall performances of the solar cells integrated with the metal NW networks are experimentally studied. It has been found the experimentally best performing NW integrated solar cell deviates from the theoretically predicated design due to the performance degradation induced by the fabrication complicity. A 6.7% efficiency enhancement was achieved for the solar cell with metal NW network integrated on top of a 60 nm thick ITO layer compared to the cell with only the ITO layer due to enhanced electrical conductivity by the metal NW network.

  12. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Flare

    Science.gov (United States)

    Barghouty, A. F.; Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Cohen, C. M. S.; Cummings, A. C.; Labrador, A. W.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We discuss observations of energetic neutral hydrogen atoms (ENAs) from a solar flare/coronal mass ejection event reported by Mewaldt et al. (2009). The observations were made during the 5 December 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV particles arriving from the Sun. The derived solar emission profile, arrival directions, and energy spectrum all show that the atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. CME-driven shock acceleration is also considered. Taking into account ENA losses, we conclude that the observed ENAs must have been produced in the high corona at heliocentric distances .2 solar radii.

  13. Application of metal nanowire networks on hydrogenated amorphous silicon thin film solar cells.

    Science.gov (United States)

    Xie, Shouyi; Hou, Guofu; Chen, Peizhuan; Jia, Baohua; Gu, Min

    2017-02-24

    We demonstrate the application of metal nanowire (NW) networks as a transparent electrode on hydrogenated amorphous Si (a-Si:H) solar cells. We first systematically investigate the optical performances of the metal NW networks on a-Si:H solar cells in different electrode configurations through numerical simulations to fully understand the mechanisms to guide the experiments. The theoretically optimized configuration is discovered to be metal NWs sandwiched between a 40 nm indium tin oxide (ITO) layer and a 20 nm ITO layer. The overall performances of the solar cells integrated with the metal NW networks are experimentally studied. It has been found the experimentally best performing NW integrated solar cell deviates from the theoretically predicated design due to the performance degradation induced by the fabrication complicity. A 6.7% efficiency enhancement was achieved for the solar cell with metal NW network integrated on top of a 60 nm thick ITO layer compared to the cell with only the ITO layer due to enhanced electrical conductivity by the metal NW network.

  14. Advantages of N-Type Hydrogenated Microcrystalline Silicon Oxide Films for Micromorph Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Amornrat Limmanee

    2013-01-01

    Full Text Available We report on the development and application of n-type hydrogenated microcrystalline silicon oxide films (n μc-SiO:H in hydrogenated amorphous silicon oxide/hydrogenated microcrystalline silicon (a-SiO:H/μc-Si:H micromorph solar cells. The n μc-SiO:H films with high optical bandgap and low refractive index could be obtained when a ratio of carbon dioxide (CO2 to silane (SiH4 flow rate was raised; however, a trade-off against electrical property was observed. We applied the n μc-SiO:H films in the top a-SiO:H cell and investigated the changes in cell performance with respect to the electrical and optical properties of the films. It was found that all photovoltaic parameters of the micromorph silicon solar cells using the n top μc-SiO:H layer enhanced with increasing the CO2/SiH4 ratio up to 0.23, where the highest initial cell efficiency of 10.7% was achieved. The enhancement of the open circuit voltage (Voc was likely to be due to a reduction of reverse bias at subcell connection—n top/p bottom interface—and a better tunnel recombination junction contributed to the improvement in the fill factor (FF. Furthermore, the quantum efficiency (QE results also have demonstrated intermediate-reflector function of the n μc-SiO:H films.

  15. Current Status of Study on Hydrogen Production with Space Solar Power Systems (SSPS)

    Science.gov (United States)

    Mori, M.; Kagawa, H.; Nagayama, H.; Saito, Y.

    2004-12-01

    Japan Aerospace Exploration Agency (JAXA) has been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. The microwave based SSPS are huge solar power systems that generate GW power by solar cells. The electric power is transmitted via microwave from the SSPS to the ground. In the laser based SSPS, a solar condenser equipped with lenses or mirrors and laser-generator would be put into orbit. A laser beam would be sent to Earth-based hydrogen generating device. We are proposing a roadmap that consists of a stepwise approach to achieve commercial SSPS in 20-30 years. The first step is 50kW class Technology Demonstration Satellite to demonstrate microwave power transmission. The second step is to demonstrate robotic assembly of 10MW class large scale flexible structure in space on ISS co-orbit. The third step is to build a prototype SSPS in GEO. The final step is to build commercial SSPS in GEO. We continue the study of SSPS concepts and architectures, technology flight demonstration and major technology development. System design of tens of kW class Technology Demonstration Satellite and conceptual study of 10MW class demonstration system on ISS co-orbit are also conducted. Several key technologies which are needed to be developed in appropriate R&D roadmap, such as high-voltage solar cell array, fiber type of direct solar pumping solid-state laser, high efficiency magnetron, thermal control technology and control technology of large scale flexible structure etc. are also investigated. In the study of concept design of commercial SSPS mentioned above, we have studied some configurations of both microwave based SSPS and laser based SSPS. In case of microwave based SSPS, the solar energy must be converted to electricity and then converted to a microwave beam. The on-ground rectifying antenna will collect the microwave beam and convert it to electricity to connect

  16. Efficiency Evaluation of a Photovoltaic System Simultaneously Generating Solar Electricity and Hydrogen for Energy Storage

    Directory of Open Access Journals (Sweden)

    Abermann S.

    2012-10-01

    Full Text Available The direct combination of a photovoltaic system with an energy storage component appears desirable since it produces and stores electrical energy simultaneously, enabling it to compensate power generation fluctuations and supply sufficient energy during low- or non-irradiation periods. A novel concept based on hydrogenated amorphous silicon (a-Si:H triple-junction solar cells, as for example a-Si:H/a-SiGe:H/a-SiGe:H, and a solar water splitting system integrating a polymer electrolyte membrane (PEM electrolyser is presented. The thin film layer-by-layer concept allows large-area module fabrication applicable to buildings, and exhibits strong cost-reduction potential as compared to similar concepts. The evaluation shows that it is possible to achieve a sufficient voltage of greater than 1.5 V for effective water splitting with the a-Si based solar cell. Nevertheless, in the case of grid-connection, the actual energy production cost for hydrogen storage by the proposed system is currently too high.

  17. Enhanced Solar-to-Hydrogen Generation with Broadband Epsilon-Near-Zero Nanostructured Photocatalysts

    KAUST Repository

    Tian, Yi

    2017-05-08

    The direct conversion of solar energy into fuels or feedstock is an attractive approach to address increasing demand of renewable energy sources. Photocatalytic systems relying on the direct photoexcitation of metals have been explored to this end, a strategy that exploits the decay of plasmonic resonances into hot carriers. An efficient hot carrier generation and collection requires, ideally, their generation to be enclosed within few tens of nanometers at the metal interface, but it is challenging to achieve this across the broadband solar spectrum. Here the authors demonstrate a new photocatalyst for hydrogen evolution based on metal epsilon-near-zero metamaterials. The authors have designed these to achieve broadband strong light confinement at the metal interface across the entire solar spectrum. Using electron energy loss spectroscopy, the authors prove that hot carriers are generated in a broadband fashion within 10 nm in this system. The resulting photocatalyst achieves a hydrogen production rate of 9.5 µmol h-1  cm-2 that exceeds, by a factor of 3.2, that of the best previously reported plasmonic-based photocatalysts for the dissociation of H2 with 50 h stable operation.

  18. Solar thermal hydrogen production process. Annual technical progress report, January-December, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Parker, G.H.

    1979-01-01

    Westinghouse is currently under contract to DOE for technology development of the Sulfur Cycle, a hybrid thermochemical-electrochemical process for the production of hydrogen and oxygen from water. Operational studies have been conducted and have resulted in definitions of operating modes for solar/hydrogen plants and in assessments of the day/night and annual variations in performance that will influence the operating modes and the sizing of plant subsystems. Conceptual design studies have been conducted for process components that interface with the solar receiver. From related trade-off studies, a preferred configuration emerged that involves an intermediate working fluid (e.g., hot gas) between the solar receiver and the sulfuric acid decomposition reactor. The design of the reactor has been based on a shell and tube type heat exchanger configuration with catalyst placement on the shell side. A number of candidate materials for structural use in the acid decomposition reactor also have been evaluated experimentally. Screening tests and endurance tests with potential catalysts (to accelerate the rate of sulfur trioxide cracking) have been conducted with encouraging results. Approximately three dozen candidate materials for use in constructing the acid vaporizer have been tested for corrosion resistance to the expected environment. Detailed discussions of the results obtained during 1979 are presented.

  19. Series circuit of organic thin-film solar cells for conversion of water into hydrogen.

    Science.gov (United States)

    Aoki, Atsushi; Naruse, Mitsuru; Abe, Takayuki

    2013-07-22

    A series circuit of bulk hetero-junction (BHJ) organic thin-film solar cells (OSCs) is investigated for electrolyzing water to gaseous hydrogen and oxygen. The BHJ OSCs applied consist of poly(3-hexylthiophene) as a donor and [6,6]-phenyl C61 butyric acid methyl ester as an acceptor. A series circuit of six such OSC units has an open circuit voltage (V(oc)) of 3.4 V, which is enough to electrolyze water. The short circuit current (J(sc)), fill factor (FF), and energy conversion efficiency (η) are independent of the number of unit cells. A maximum electric power of 8.86 mW cm(-2) is obtained at the voltage of 2.35 V. By combining a water electrolysis cell with the series circuit solar cells, the electrolyzing current and voltage obtained are 1.09 mA and 2.3 V under a simulated solar light irradiation (100 mW cm(-2), AM1.5G), and in one hour 0.65 mL hydrogen is generated.

  20. Observations and Interpretations of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Barghouty, A. f.; Cohen, C. M. S.; Cummings, A. c.; Labrador, A. W.; vonRosenvinge, T. T.

    2009-01-01

    We discuss recently reported observations of energetic neutral hydrogen atoms (ENAs) from an X9 solar flare/coronal mass ejection event on 5 December 2006, located at E79. The observations were made by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV energetic neutral hydrogen atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. Taking into account ENA losses, we find that the observed ENAs must have been produced in the high corona at heliocentric distances > or equal to 2 solar radii. Although there are no CME images from this event, it is shown that CME-shock-accelerated protons can, in principle, produce a time-history consistent with the observations.

  1. Investigation of advanced nanostructured multijunction photoanodes for enhanced solar hydrogen generation via water splitting

    Science.gov (United States)

    Ishihara, Hidetaka

    As the worldwide demand for fossil-based fuel increases every day and the fossil reserve continues to be depleted, the need for alternative/renewable energy sources has gained momentum. Electric, hybrid, and hydrogen cars have been at the center of discussion lately among consumers, automobile manufacturers, and politicians, alike. The development of a fuel-cell based engine using hydrogen has been an ambitious research area over the last few decades-ever since Fujishima showed that hydrogen can be generated via the solar-energy driven photo-electrolytic splitting of water. Such solar cells are known as Photo-Electro-Chemical (PEC) solar cells. In order to commercialize this technology, various challenges associated with photo-conversion efficiency, chemical corrosion resistance, and longevity need to be overcome. In general, metal oxide semiconductors such as titanium dioxide (TiO 2, titania) are excellent candidates for PEC solar cells. Titania nanotubes have several advantages, including biocompatibility and higher chemical stability. Nevertheless, they can absorb only 5-7% of the solar spectrum which makes it difficult to achieve the higher photo-conversion efficiency required for successful commercial applications. A two-prong approach was employed to enhance photo-conversion efficiency: 1) surface modification of titania nanotubes using plasma treatment and 2) nano-capping of the titania nanotubes using titanium disilicide. The plasma surface treatment with N2 was found to improve the photo-current efficiency of titania nanotubes by 55%. Similarly, a facile, novel approach of nano-capping titania nanotubes to enhance their photocurrent response was also investigated. Electrochemically anodized titania nanotubes were capped by coating a 25 nm layer of titanium disilicide using RF magnetron sputtering technique. The optical properties of titania nanotubes were not found to change due to the capping; however, a considerable increase (40%) in the photocurrent

  2. Design of a Simple and Cheap Water Electrolyser for the Production of Solar Hydrogen

    Directory of Open Access Journals (Sweden)

    R. Prasad

    2009-06-01

    Full Text Available Commercially available conventional alkaline electrolyser and advanced polymer membrane electrolysers for water electrolysis are quite expensive. Taking into account this aspect, a very simple and cheap water electrolyser has been designed and fabricated utilising easily available economical materials for small scale production of hydrogen using renewable energy from photovoltaic panel. The construction details of the electrolyser with a schematic drawing of the experimental set-up for PV production of H2 are given. In order to fabricate the compact electrolyser, two coaxial tubular PVC pipes were used. The lower part of the inner pipe has fine perforations for the transport of ions through electrolyte between the electrodes. Two cylindrical electrodes, cathode and anode are kept in inner and outer pipes respectively. The performance of hydrogen production was measured using a photovoltaic panel directly connected to the electrolyser under atmospheric pressure and in 27wt% KOH solution. Flow rates of hydrogen and oxygen were measured using a digital flow meter. High purity fuel cell grade hydrogen (99.98% and oxygen (99.85% have been produced. The experimental results confirm that the present electrolyser has eligible properties for hydrogen production in remote areas. No such electrolyser has been reported prior to this work. Copyright (c 2009 by BCREC. All rights reserved.[Received: 20 May 2009, Revised: 14 August 2009, Accepted: 19 August 2009][How to Cite: R. Prasad. (2009. Design of a Simple and Cheap Water Electrolyser for the Production of Solar Hydrogen. Bulletin of Chemical Reaction Engineering and Catalysis, 4(1: 10-15. doi:10.9767/bcrec.4.1.21.10-15][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.1.21.10-15

  3. Design of a Simple and Cheap Water Electrolyser for the Production of Solar Hydrogen

    Directory of Open Access Journals (Sweden)

    Ram Prasad

    2009-06-01

    Full Text Available Commercially available conventional alkaline electrolyser and advanced polymer membrane electrolysers for water electrolysis are quite expensive. Taking into account this aspect, a very simple and cheap water electrolyser has been designed and fabricated utilising easily available economical materials for small scale production of hydrogen using renewable energy from photovoltaic panel. The construction details of the electrolyser with a schematic drawing of the experimental set-up for PV production of H2 are given. In order to fabricate the compact electrolyser, two coaxial tubular PVC pipes were used. The lower part of the inner pipe has fine perforations for the transport of ions through electrolyte between the electrodes. Two cylindrical electrodes, cathode and anode are kept in inner and outer pipes respectively. The performance of hydrogen production was measured using a photovoltaic panel directly connected to the electrolyser under atmospheric pressure and in 27wt% KOH solution. Flow rates of hydrogen and oxygen were measured using a digital flow meter. High purity fuel cell grade hydrogen (99.98% and oxygen (99.85% have been produced. The experimental results confirm that the present electrolyser has eligible properties for hydrogen production in remote areas. No such electrolyser has been reported prior to this work. Copyright (c 2009 by BCREC. All rights reserved.[Received: 20 May 2009, Revised: 14 August 2009, Accepted: 19 August 2009][How to Cite: R. Prasad. (2009. Design of a Simple and Cheap Water Electrolyser for the Production of Solar Hydrogen. Bulletin of Chemical Reaction Engineering and Catalysis, 4(1: 10-15.  doi:10.9767/bcrec.4.1.7113.10-15][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.1.7113.10-15 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7113 ] 

  4. Solar-powered electrochemical oxidation of organic compounds coupled with the cathodic production of molecular hydrogen.

    Science.gov (United States)

    Park, Hyunwoong; Vecitis, Chad D; Hoffmann, Michael R

    2008-08-21

    A Bi-doped TiO2 anode, which is prepared from a mixed metal oxide coating deposited on Ti metal, is shown to be efficient for conventional water splitting. In this hybrid photovoltaic-electrochemical system, a photovoltaic (PV) cell is used to convert solar light to electricity, which is then used to oxidize a series of phenolic compounds at the semiconductor anode to carbon dioxide with the simultaneous production of molecular hydrogen from water/proton reduction at the stainless steel cathode. Degradation of phenol in the presence of a background NaCl electrolyte produces chlorinated phenols as reaction intermediates, which are subsequently oxidized completely to carbon dioxide and low-molecular weight carboxylic acids. The anodic current efficiency for the complete oxidation of phenolic compounds ranges from 3% to 17%, while the cathodic current efficiency and the energy efficiency for hydrogen gas generation range from 68% to 95% and 30% to 70%, respectively.

  5. Hydrogen related phenomena at the ITO/a-Si:H/Si heterojunction solar cell interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ulyashin, Alexander [SINTEF Materials and Chemistry, Forskningsveien 1, P.O. Box 124, 0314 Oslo (Norway); Sytchkova, Anna [Optical Coatings Laboratory, ENEA Casaccia C.R.E., via Anguillarese 301, 00123 Rome (Italy)

    2013-04-15

    Properties of thin a-Si:H and indium-tin oxide (ITO) layers as well as properties of interfaces of Si based heterojunction (HJ) ITO/(p)a-Si:H/n-Si structures were analyzed by means of atomic force microscopy (AFM) and scanning spreading resistance microscopy. It is shown that the morphology of thin ITO layers grown on n-type polished crystalline Si or on (p)a-Si:H/n-Si substrates depends on the deposition temperature and has peculiarities on nano-scale. Formation of highly conductive nano-dots on the surface and in the bulk of ITO layers is found. The observed nano-spots and nano-dots are attributed to the influence of hydrogen initiated reduction process, which occurs upon deposition of ITO films on an a-Si:H layer during the fabrication process of a HJ solar cell. This fact is confirmed by investigation of morphological properties of ITO surfaces after treatment by hydrogen plasma. It is shown that formation of conductive nano-particles on the ITO surface initiated by hydrogen does not change essentially transparency of an ITO layer. It is concluded that conductive nano-dots at the ITO/a-Si:H interface can be considered as local conductive channels, which provide a current flow through the ITO/(p)a-Si:H interface without essential shadowing of the solar cell structure. This finding opens an interesting way for the optimization of properties of the ITO/Si-based HJ solar cells. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Hydrogen production by hybrid electrolysis combined with assistance of solar energy

    Science.gov (United States)

    Takehara, Z.; Yoshizawa, S.

    As a means of reducing the electrical energy needed to produce hydrogen from water, a process is presented, whereby an aqueous sulfuric acid solution containing Fe(2+) ions is electrolyzed, hydrogen being an energy storage material which levels load variation of electrical utilities. In an electrolytic cell, Fe(2+) ions are oxidized on a packed bed carbon anode to form Fe(3+) ions. H(+) ions diffuse through a cation exchange membrane, and are then reduced to hydrogen gas on the cathode. The Fe(3+) ions, produced in the cell, are decomposed in a photodecomposition cell. Oxygen evolves on the TiO2 anode, illuminated by solar light; the produced H(+) ions are diffused through a cation exchange membrane and electrons move through the metal inserted in the membrane to the cathode. The solution containing Fe(+) ions, introduced in the cathode chamber, is reduced cathodically on the platinized platinum. Cell voltage is determined for the process and it is found to be only about 1.0 V for electrolysis of 50mA/sq cm at room temperature. For the case of direct electrolysis of 2N NaOH aqueous solution, the cell voltage is 2.2V electrolysis of 30mA/sq cm. Results indicate a large reduction of electrical energy needed for the production of hydrogen in the process presented.

  7. Laser assisted patterning of hydrogenated amorphous silicon for interdigitated back contact silicon heterojunction solar cell

    Science.gov (United States)

    De Vecchi, S.; Desrues, T.; Souche, F.; Muñoz, D.; Lemiti, M.

    2012-10-01

    This work reports on the elaboration of a new industrial process based on laser selective ablation of dielectric layers for Interdigitated Back Contact Silicon Heterojunction (IBC Si-HJ) solar cells fabrication. Choice of the process is discussed and cells are processed to validate its performance. A pulsed green laser (515nm) with 10-20ns pulse duration is used for hydrogenated amorphous silicon (a-Si:H) layers patterning steps, whereas metallization is made by screen printed. High Open-Circuit Voltage (Voc=699mV) and Fill Factor (FF=78.5%) values are obtained simultaneously on IBC Si-HJ cells, indicating a high surface passivation level and reduced resistive losses. An efficiency of 19% on non textured 26 cm² solar cells has been reached with this new industrial process.

  8. Solar Weather Ice Monitoring Station (SWIMS). A low cost, extreme/harsh environment, solar powered, autonomous sensor data gathering and transmission system

    Science.gov (United States)

    Chetty, S.; Field, L. A.

    2013-12-01

    The Arctic ocean's continuing decrease of summer-time ice is related to rapidly diminishing multi-year ice due to the effects of climate change. Ice911 Research aims to develop environmentally respectful materials that when deployed will increase the albedo, enhancing the formation and/preservation of multi-year ice. Small scale deployments using various materials have been done in Canada, California's Sierra Nevada Mountains and a pond in Minnesota to test the albedo performance and environmental characteristics of these materials. SWIMS is a sophisticated autonomous sensor system being developed to measure the albedo, weather, water temperature and other environmental parameters. The system (SWIMS) employs low cost, high accuracy/precision sensors, high resolution cameras, and an extreme environment command and data handling computer system using satellite and terrestrial wireless communication. The entire system is solar powered with redundant battery backup on a floating buoy platform engineered for low temperature (-40C) and high wind conditions. The system also incorporates tilt sensors, sonar based ice thickness sensors and a weather station. To keep the costs low, each SWIMS unit measures incoming and reflected radiation from the four quadrants around the buoy. This allows data from four sets of sensors, cameras, weather station, water temperature probe to be collected and transmitted by a single on-board solar powered computer. This presentation covers the technical, logistical and cost challenges in designing, developing and deploying these stations in remote, extreme environments. Image captured by camera #3 of setting sun on the SWIMS station One of the images captured by SWIMS Camera #4

  9. Modeling of the steam hydrolysis in a two-step process for hydrogen production by solar concentrated energy

    Science.gov (United States)

    Valle-Hernández, Julio; Romero-Paredes, Hernando; Pacheco-Reyes, Alejandro

    2017-06-01

    In this paper the simulation of the steam hydrolysis for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 to lower-valence cerium oxide, at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. The modeling of endothermic reduction step was presented at the Solar Paces 2015. This work shows the modeling of the exothermic step; the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For this model, three sections of the pipe where the reaction occurs were considered; the steam water inlet, the porous medium and the hydrogen outlet produced. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

  10. Co-catalyst free Titanate Nanorods for improved Hydrogen production under solar light irradiation

    Indian Academy of Sciences (India)

    N Lakshmana Reddy; D Praveen Kumar; M V Shankar

    2016-04-01

    Harnessing solar energy for water splitting into hydrogen (H2) and oxygen (O2) gases in the presence of semiconductor catalyst is one of the most promising and cleaner methods of chemical fuel (H2) production. Herein, we report a simplified method for the preparation of photo-active titanate nanorods catalyst and explore the key role of calcination temperature and time period in improving catalytic properties. Both as-synthesized and calcined material showed rod-like shape and trititanate structure as evidenced from crystal structure and morphology analysis. Notably, calcination process affected both length and diameter of the nanorods into shorter and smaller size respectively. In turn, they significantly influenced the band gap reduction, resulting in visible light absorption at optimized calcination conditions. The calcined nanorods showed shift in optical absorption band edge towards longer wave length than pristine nanorods. The rate of hydrogen generation using different photocatalysts was measured by suspending trititanate nanorods (in the absence of co-catalyst) in glycerol-water mixture under solar light irradiation. Among the catalysts, nanorods calcined at 250°C for 2 hours recorded high rate of H2 production and stability confirmed for five cycles. Photocatalytic properties and plausible pathway responsible for improved H2 production are discussed in detail.

  11. Solar thermal hydrogen production process: Final report, January 1978-December 1982

    Energy Technology Data Exchange (ETDEWEB)

    1982-12-01

    Under sponsorship by the United States Department of Energy, Westinghouse Advanced Energy-Systems Division has investigated the potential for using solar thermal energy to split water into hydrogen and oxygen. A hybrid thermochemical/electrochemical process, known as the Sulfur Cycle, has been the focus of these investigations. Process studies have indicated that, with adequate and ongoing research and development, the Sulfur Cycle can be effectively driven with solar heat. Also, economic analyses have indicated that the cycle has the potential to produce hydrogen in economic competitiveness with conventional methods (e.g. methane/steam reforming) by the turn of the century. A first generation developmental system has been defined along with its critical components, i.e. those components that need substantial engineering development. Designs for those high temperature components that concentrate, vaporize and decompose the process circulating fluid, sulfuric acid, have been prepared. Extensive experimental investigations have been conducted with regard to the selection of construction materials for these components. From these experiments, which included materials endurance tests for corrosion resistance for periods up to 6000 hours, promising materials and catalysts have been identified.

  12. Engineering MoSx/Ti/InP Hybrid Photocathode for Improved Solar Hydrogen Production

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Zhong, Miao; Ma, Liguo; Wang, Faze; Ma, Li; Shen, Wenzhong

    2016-07-01

    Due to its direct band gap of ~1.35 eV, appropriate energy band-edge positions, and low surface-recombination velocity, p-type InP has attracted considerable attention as a promising photocathode material for solar hydrogen generation. However, challenges remain with p-type InP for achieving high and stable photoelectrochemical (PEC) performances. Here, we demonstrate that surface modifications of InP photocathodes with Ti thin layers and amorphous MoSx nanoparticles can remarkably improve their PEC performances. A high photocurrent density with an improved PEC onset potential is obtained. Electrochemical impedance analyses reveal that the largely improved PEC performance of MoSx/Ti/InP is attributed to the reduced charge-transfer resistance and the increased band bending at the MoSx/Ti/InP/electrolyte interface. In addition, the MoSx/Ti/InP photocathodes function stably for PEC water reduction under continuous light illumination over 2 h. Our study demonstrates an effective approach to develop high-PEC-performance InP photocathodes towards stable solar hydrogen production.

  13. An Integrated Photoelectrochemical-Chemical Loop for Solar-Driven Overall Splitting of Hydrogen Sulfide

    DEFF Research Database (Denmark)

    Zong, Xu; Han, Jingfeng; Seger, Brian

    2014-01-01

    Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H-2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop...... simulated solar light. This new conceptual design will not only provide a possible route for using solar energy to convert H2S into valuable resources, but also sheds light on some challenging photochemical reactions such as CH4 activation and CO2 reduction.......Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H-2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop...... linked by redox couples such as Fe2+/Fe3+ and I-/I-3(-) for photoelectrochemical H-2 production and H2S chemical absorption redox reactions are reported. Using functionalized Si as photoelectrodes, H2S was successfully split into elemental sulfur and H-2 with high stability and selectivity under...

  14. Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes.

    Science.gov (United States)

    Gençer, Emre; Mallapragada, Dharik S; Maréchal, François; Tawarmalani, Mohit; Agrawal, Rakesh

    2015-12-29

    We introduce a paradigm-"hydricity"-that involves the coproduction of hydrogen and electricity from solar thermal energy and their judicious use to enable a sustainable economy. We identify and implement synergistic integrations while improving each of the two individual processes. When the proposed integrated process is operated in a standalone, solely power production mode, the resulting solar water power cycle can generate electricity with unprecedented efficiencies of 40-46%. Similarly, in standalone hydrogen mode, pressurized hydrogen is produced at efficiencies approaching ∼50%. In the coproduction mode, the coproduced hydrogen is stored for uninterrupted solar power production. When sunlight is unavailable, we envision that the stored hydrogen is used in a "turbine"-based hydrogen water power (H2WP) cycle with the calculated hydrogen-to-electricity efficiency of 65-70%, which is comparable to the fuel cell efficiencies. The H2WP cycle uses much of the same equipment as the solar water power cycle, reducing capital outlays. The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-h cycle, is shown to approach ∼35%, which is nearly the efficiency attained by using the best multijunction photovoltaic cells along with batteries. In comparison, our proposed process has the following advantages: (i) It stores energy thermochemically with a two- to threefold higher density, (ii) coproduced hydrogen has alternate uses in transportation/chemical/petrochemical industries, and (iii) unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses.

  15. Solar modulation of hydrogen and helium cosmic ray nuclei spectra above 400 MeV/Nucleon, from 1976 to 1993

    Energy Technology Data Exchange (ETDEWEB)

    Morselli, A.; Picozza, P. [Rome Univ. `Tor Vergata` (Italy)]|[INFN, Rome (Italy); Barbiellini, G. [Trieste Univ. (Italy)]|[INFN, Sezione Univ.Trieste (Italy); Golden, R.L.; Paradis, P.J.; Stochaj, S.J. [New Mexico State Univ., Las Cruces, NM (United States). Particle Astrophysics Laboratory; Mauger, B.G.; Horan, S. [Physical Science laboratory, Las Cruces, NM (United States); Badwhar, G.D.; Daniel, R.R. [NASA Johnson Space Center, Houston, TX (United States)

    1995-09-01

    Hydrogen and helium cosmic ray nuclei spectra gathered from 1976 to 1993 have been corrected to the top of the atmosphere and normalized at high rigidities. The variation of these primary cosmic ray fluxes above 400 MeV/nucleon has been examined as a function of the phase of the solar cycle with the force-field approximation model. The intensity of the normalized fluxes between solar maximum and minimum conditions varies by a factor of 6 for hydrogen and a factor of 4.3 for helium at the lowest rigidities considered.

  16. Reactor Design for CO2 Photo-Hydrogenation toward Solar Fuels under Ambient Temperature and Pressure

    Directory of Open Access Journals (Sweden)

    Chun-Ying Chen

    2017-02-01

    Full Text Available Photo-hydrogenation of carbon dioxide (CO2 is a green and promising technology and has received much attention recently. This technique could convert solar energy under ambient temperature and pressure into desirable and sustainable solar fuels, such as methanol (CH3OH, methane (CH4, and formic acid (HCOOH. It is worthwhile to mention that this direction can not only potentially depress atmospheric CO2, but also weaken dependence on fossil fuel. Herein, 1 wt % Pt/CuAlGaO4 photocatalyst was successfully synthesized and fully characterized by ultraviolet-visible light (UV-vis spectroscopy, X-ray diffraction (XRD, Field emission scanning electron microscopy using energy dispersive spectroscopy analysis (FE-SEM/EDS, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and Brunauer-Emmett-Teller (BET, respectively. Three kinds of experimental photo-hydrogenation of CO2 in the gas phase, liquid phase, and gas-liquid phase, correspondingly, were conducted under different H2 partial pressures. The remarkable result has been observed in the gas-liquid phase. Additionally, increasing the partial pressure of H2 would enhance the yield of product. However, when an extra amount of H2 is supplied, it might compete with CO2 for occupying the active sites, resulting in a negative effect on CO2 photo-hydrogenation. For liquid and gas-liquid phases, CH3OH is the major product. Maximum total hydrocarbons 8.302 µmol·g−1 is achieved in the gas-liquid phase.

  17. Simulation of the outdoor energy efficiency of an autonomous solar kit based on meteorological data for a site in Central Europa

    Science.gov (United States)

    Bouzaki, Mohammed Moustafa; Chadel, Meriem; Benyoucef, Boumediene; Petit, Pierre; Aillerie, Michel

    2016-07-01

    This contribution analyzes the energy provided by a solar kit dedicated to autonomous usage and installed in Central Europa (Longitude 6.10°; Latitude 49.21° and Altitude 160 m) by using the simulation software PVSYST. We focused the analysis on the effect of temperature and solar irradiation on the I-V characteristic of a commercial PV panel. We also consider in this study the influence of charging and discharging the battery on the generator efficiency. Meteorological data are integrated into the simulation software. As expected, the solar kit provides an energy varying all along the year with a minimum in December. In the proposed approach, we consider this minimum as the lowest acceptable energy level to satisfy the use. Thus for the other months, a lost in the available renewable energy exists if no storage system is associated.

  18. Simulation of the outdoor energy efficiency of an autonomous solar kit based on meteorological data for a site in Central Europe

    Energy Technology Data Exchange (ETDEWEB)

    Bouzaki, Mohammed Moustafa, E-mail: bouzaki-physique1@yahoo.fr; Chadel, Meriem [University of Tlemcen URMER, 13000 (Algeria); Université de Lorraine, LMOPS, EA 4423, 57070 Metz (France); CentraleSupélec, LMOPS, 57070 Metz (France); Benyoucef, Boumediene [University of Tlemcen URMER, 13000 (Algeria); Petit, Pierre; Aillerie, Michel, E-mail: aillerie@metz.supelec.fr [Université de Lorraine, LMOPS, EA 4423, 57070 Metz (France); CentraleSupélec, LMOPS, 57070 Metz (France)

    2016-07-25

    This contribution analyzes the energy provided by a solar kit dedicated to autonomous usage and installed in Central Europe (Longitude 6.10°; Latitude 49.21° and Altitude 160 m) by using the simulation software PVSYST. We focused the analysis on the effect of temperature and solar irradiation on the I-V characteristic of a commercial PV panel. We also consider in this study the influence of charging and discharging the battery on the generator efficiency. Meteorological data are integrated into the simulation software. As expected, the solar kit provides an energy varying all along the year with a minimum in December. In the proposed approach, we consider this minimum as the lowest acceptable energy level to satisfy the use. Thus for the other months, a lost in the available renewable energy exists if no storage system is associated.

  19. Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water

    Science.gov (United States)

    Deng, Jinyi

    In this study, high purity bismuth iron oxide (BiFeO3/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 620 nm, corresponding to an energy band gap of 2.1 eV. Compared to BaTiO3, BFO has a better degradation of methyl orange under light radiation. Also, photocatalytic tests prove this material to be efficient towards water splitting under simulated solar light to generate hydrogen. The simple synthetic methodology adopted in this paper will be useful in developing low-cost semiconductor materials as effective photocatalysts for hydrogen generation. Photocatalytic tests followed by gas chromatography (GC) analyses show that BiFeO3 generates three times more hydrogen than commercial titania P25 catalyst under the same experimental conditions.

  20. Solar Abundances of Rock Forming Elements, Extreme Oxygen and Hydrogen in a Young Polluted White Dwarf

    CERN Document Server

    Farihi, J; Zuckerman, B; Vican, L; Gänsicke, B T; Smith, N; Walth, G; Breedt, E

    2016-01-01

    The Teff = 20,800 K white dwarf WD 1536+520 is shown to have broadly solar abundances of the major rock forming elements O, Mg, Al, Si, Ca, and Fe, together with a strong relative depletion in the volatile elements C and S. In addition to the highest metal abundances observed to date, including log(O/He) = -3.4, the helium-dominated atmosphere has an exceptional hydrogen abundance at log(H/He) = -1.7. Within the uncertainties, the metal-to-metal ratios are consistent with the accretion of an H2O-rich and rocky parent body, an interpretation supported by the anomalously high trace hydrogen. The mixed atmosphere yields unusually short diffusion timescales for a helium atmosphere white dwarf, of no more than a few hundred yr, and equivalent to those in a much cooler, hydrogen-rich star. The overall heavy element abundances of the disrupted parent body deviate modestly from a bulk Earth pattern, and suggest the deposition of some core-like material. The total inferred accretion rate is 4.2e9 g/s, and at least 4 t...

  1. Microscopic Measurements of Electrical Potential in Hydrogenated Nanocrystalline Silicon Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C. S.; Moutinho, H. R.; Reedy, R. C.; Al-Jassim, M. M.; Yan, B.; Yue, G.; Sivec, L.; Yang, J.; Guha, S.; Tong, X.

    2012-04-01

    We report on a direct measurement of electrical potential and field profiles across the n-i-p junction of hydrogenated nanocrystalline silicon (nc-Si:H) solar cells, using the nanometer-resolution potential imaging technique of scanning Kelvin probe force microscopy (SKPFM). It was observed that the electric field is nonuniform across the i layer. It is much higher in the p/i region than in the middle and the n/i region, illustrating that the i layer is actually slightly n-type. A measurement on a nc-Si:H cell with a higher oxygen impurity concentration shows that the nonuniformity of the electric field is much more pronounced than in samples having a lower O impurity, indicating that O is an electron donor in nc-Si:H materials. This nonuniform distribution of electric field implies a mixture of diffusion and drift of carrier transport in the nc-Si:H solar cells. The composition and structure of these nc-Si:H cells were further investigated by using secondary-ion mass spectrometry and Raman spectroscopy, respectively. The effects of impurity and structural properties on the electrical potential distribution and solar cell performance are discussed.

  2. Electrical properties and degradation behavior of hydrogenated amorphous Si alloys for solar cells

    Science.gov (United States)

    Krühler, W.; Kusian, W.; Karg, F.; Pfleiderer, H.

    1986-12-01

    The electrical properties and the degradation behavior of hydrogenated amorphous silicon alloys (a-Si1- x A x : H, with A=C, Ge, B, P) in designs of pin, pip, nin, and MOS structures are investigated by measuring the dark and light I(V) characteristics and the spectral response as well as the space-charge-limited current (SCLC), the time of flight (TOF) of carriers and the field effect (FE). These investigations give an overview of our recent work combined with new results emphasizing the physics of the a-Si:H pin solar cells. We discuss the stabilizing influence on the degradation behavior achieved by profiling the i layers of the pin solar cells with P and B. Two kinds of pin solar cells, namely glass/SnO2/p(C)in/metal and glass/metal/pin/ITO, are investigated and an explanation of their different spectral response behavior is given. SCLC measurements lead to the conclusion that trapping is also involved in the degradation mechanism, as is recombination. TOF experiments on a-Si1- x Ge x : H pin diodes indicate that the incorporation of Ge widens the tail-state distribution below the conduction band. FE measurements showed densities of gap states of about 5×l016cm-3eV-1.

  3. The role of hydrogenated amorphous silicon oxide buffer layer on improving the performance of hydrogenated amorphous silicon germanium single-junction solar cells

    Science.gov (United States)

    Sritharathikhun, Jaran; Inthisang, Sorapong; Krajangsang, Taweewat; Krudtad, Patipan; Jaroensathainchok, Suttinan; Hongsingtong, Aswin; Limmanee, Amornrat; Sriprapha, Kobsak

    2016-12-01

    Hydrogenated amorphous silicon oxide (a-Si1-xOx:H) film was used as a buffer layer at the p-layer (μc-Si1-xOx:H)/i-layer (a-Si1-xGex:H) interface for a narrow band gap hydrogenated amorphous silicon germanium (a-Si1-xGex:H) single-junction solar cell. The a-Si1-xOx:H film was deposited by plasma enhanced chemical vapor deposition (PECVD) at 40 MHz in a same processing chamber as depositing the p-type layer. An optimization of the thickness of the a-Si1-xOx:H buffer layer and the CO2/SiH4 ratio was performed in the fabrication of the a-Si1-xGex:H single junction solar cells. By using the wide band gap a-Si1-xOx:H buffer layer with optimum thickness and CO2/SiH4 ratio, the solar cells showed an improvement in the open-circuit voltage (Voc), fill factor (FF), and short circuit current density (Jsc), compared with the solar cells fabricated using the conventional a-Si:H buffer layer. The experimental results indicated the excellent potential of the wide-gap a-Si1-xOx:H buffer layers for narrow band gap a-Si1-xGex:H single junction solar cells.

  4. An Isotope Study of Hydrogenation of poly-Si/SiOx Passivated Contacts for Si Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, Manuel; Nemeth, William; van de Loo, Bas, W.H.; Macco, Bart; Kessels, Wilhelmus, M.M.; Stradins, Paul; Young, David, L.

    2017-06-26

    For many years, the record Si solar cell efficiency stood at 25.0%. Only recently have several companies and institutes managed to produce more efficient cells, using passivated contacts of made doped poly-Si or a-Si:H and a passivating intrinsic interlayer in all cases. Common to these designs is the need to passivate the layer stack with hydrogen. In this contribution, we perform a systematic study of passivated contact passivation by hydrogen, using poly-Si/SiOx passivated contacts on n-Cz-Si, and ALD Al2O3 followed by a forming gas anneal (FGA) as the hydrogen source. We study p-type and n-type passivated contacts with implied Voc exceeding 690 and 720 mV, respectively, and perform either the ALD step or the FGA with deuterium instead of hydrogen in order to separate the two processes via SIMS. By examining the deuterium concentration at the SiOx in both types of samples, we demonstrate that the FGA supplies negligible hydrogen species to the SiOx, regardless of whether the FGA is hydrogenated or deuterated. Instead, it supplies the thermal energy needed for hydrogen species in the Al2O3 to diffuse there. Furthermore, the concentration of hydrogen species at the SiOx can saturate while implied Voc continues to increase, showing that the energy from the FGA is also required for hydrogen species already at the SiOx to find recombination-active defects to passivate.

  5. Time-dependent hydrogen ionisation in 3D simulations of the solar chromosphere. Methods and first results

    NARCIS (Netherlands)

    Leenaarts, J.; Wedemeyer-Bohm, S.

    2006-01-01

    Context. The hydrogen ionisation degree deviates substantially from statistical equilibrium under the conditions of the solar chromosphere. A realistic description of this atmospheric layer thus must account for time-dependent non-equilibrium effects. Aims. Advancing the realism of numerical simulat

  6. Optimization studies of bio-hydrogen production in a coupled microbial electrolysis-dye sensitized solar cell system.

    Science.gov (United States)

    Ajayi, Folusho Francis; Kim, Kyoung-Yeol; Chae, Kyu-Jung; Choi, Mi-Jin; Chang, In Seop; Kim, In S

    2010-03-01

    Bio-hydrogen production in light-assisted microbial electrolysis cell (MEC) with a dye sensitized solar cell (DSSC) was optimized by connecting multiple MECs to a single dye (N719) sensitized solar cell (V(OC) approx. 0.7 V). Hydrogen production occurred simultaneously in all the connected MECs when the solar cell was irradiated with light. The amount of hydrogen produced in each MEC depends on the activity of the microbial catalyst on their anode. Substrate (acetate) to hydrogen conversion efficiencies ranging from 42% to 65% were obtained from the reactors during the experiment. A moderate light intensity of 430 W m(-2) was sufficient for hydrogen production in the coupled MEC-DSSC. A higher light intensity of 915 W m(-2), as well as an increase in substrate concentration, did not show any improvement in the current density due to limitation caused by the rate of microbial oxidation on the anode. A significant reduction in the surface area of the connected DSSC only showed a slight effect on current density in the coupled MEC-DSSC system when irradiated with light.

  7. Strategic partnerships final LDRD report : nanocomposite materials for efficient solar hydrogen production.

    Energy Technology Data Exchange (ETDEWEB)

    Corral, Erica L. (University of Arizona, Tucson, AZ); Miller, James Edward; Walker, Luke S. (University of Arizona, Tucson, AZ); Evans, Lindsey R.

    2012-05-01

    This 'campus executive' project sought to advance solar thermochemical technology for producing the chemical fuels. The project advanced the common interest of Sandia National Laboratories and the University of Arizona in creating a sustainable and viable alternative to fossil fuels. The focus of this effort was in developing new methods for creating unique monolithic composite structures and characterizing their performance in thermochemical production of hydrogen from water. The development and processing of the materials was undertaken in the Materials Science and Engineering Department at the University of Arizona; Sandia National Laboratories performed the thermochemical characterization. Ferrite/yttria-stabilized zirconia composite monoliths were fabricated and shown to have exceptionally high utilization of the ferrite for splitting CO{sub 2} to obtain CO (a process analogous to splitting H{sub 2}O to obtain H{sub 2}).

  8. Dark Photocatalysis: Storage of Solar Energy in Carbon Nitride for Time-Delayed Hydrogen Generation.

    Science.gov (United States)

    Lau, Vincent Wing-Hei; Klose, Daniel; Kasap, Hatice; Podjaski, Filip; Pignié, Marie-Claire; Reisner, Erwin; Jeschke, Gunnar; Lotsch, Bettina V

    2017-01-09

    While natural photosynthesis serves as the model system for efficient charge separation and decoupling of redox reactions, bio-inspired artificial systems typically lack applicability owing to synthetic challenges and structural complexity. We present herein a simple and inexpensive system that, under solar irradiation, forms highly reductive radicals in the presence of an electron donor, with lifetimes exceeding the diurnal cycle. This radical species is formed within a cyanamide-functionalized polymeric network of heptazine units and can give off its trapped electrons in the dark to yield H2 , triggered by a co-catalyst, thus enabling the temporal decoupling of the light and dark reactions of photocatalytic hydrogen production through the radical's longevity. The system introduced here thus demonstrates a new approach for storing sunlight as long-lived radicals, and provides the structural basis for designing photocatalysts with long-lived photo-induced states.

  9. Modeling of a CeO2 thermochemistry reduction process for hydrogen production by solar concentrated energy

    Science.gov (United States)

    Valle-Hernández, Julio; Romero-Paredes, Hernando; Arancibia-Bulnes, Camilo A.; Villafan-Vidales, Heidi I.; Espinosa-Paredes, Gilberto

    2016-05-01

    In this paper the simulation of the thermal reduction for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. For the thermochemical process, a solar reactor prototype is proposed; consisting of a cubic receptacle made of graphite fiber thermally insulated. Inside the reactor a pyramidal arrangement with nine tungsten pipes is housed. The pyramidal arrangement is made respect to the focal point where the reflected energy is concentrated. The solar energy is concentrated through the solar furnace of high radiative flux. The endothermic step is the reduction of the cerium oxide to lower-valence cerium oxide, at very high temperature. The exothermic step is the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For the modeling, three sections of the pipe where the reaction occurs were considered; the carrier gas inlet, the porous medium and the reaction products outlet. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

  10. Photo-electrochemical hydrogen generation using band-gap modified nanotubular titanium oxide in solar light

    Science.gov (United States)

    Raja, K. S.; Misra, M.; Mahajan, V. K.; Gandhi, T.; Pillai, P.; Mohapatra, S. K.

    Anodization of Ti in acidified fluoride solution results in an ordered nanotubular titanium oxide surface. In this study, vertically oriented arrays of TiO 2 nanotubes were prepared by incorporating nitrate and phosphate species during the anodization process. These nanotubes were annealed at 650 °C in a carbonaceous atmosphere using a chemical vapor deposition (CVD) furnace for a brief period. The carbon-modified nanotubular TiO 2 produced a photo-current density of more than 2.75 mA cm -2 at 0.2 V Ag/AgCl under solar light illumination. This photo-current density corresponds to a hydrogen evolution rate of about 11 l h -1 using a photo-anode of 1 m 2 area. The enhanced hydrogen evolution behavior of carbon-modified nanotubular TiO 2 is highly reproducible and sustainable for long duration. Annealed (at 350 °C in nitrogen atmosphere) TiO 2 nanotubes showed improved photo-activity as compared to the as-anodized or thermally oxidized TiO 2 photo-anodes.

  11. Multi-Generation Concentrating Solar-Hydrogen Power System for Sustainable Rural Development

    Energy Technology Data Exchange (ETDEWEB)

    Krothapalli, A.; Greska, B.

    2007-07-01

    This paper describes an energy system that is designed to meet the demands of rural populations that currently have no access to grid-connected electricity. Besides electricity, it is well recognized that rural populations need at least a centralized refrigeration system for storage of medicines and other emergency supplies, as well as safe drinking water. Here we propose a district system that will employ a multi-generation concentrated solar power (CSP) system that will generate electricity and supply the heat needed for both absorption refrigeration and membrane distillation (MD) water purification. The electricity will be used to generate hydrogen through highly efficient water electrolysis and individual households can use the hydrogen for generating electricity, via affordable proton exchange membrane (PEM) fuel cells, and as a fuel for cooking. The multi-generation system is being developed such that its components will be easy to manufacture and maintain. As a result, these components will be less efficient than their typical counterparts but their low cost-to-efficiency ratio will allow for us to meet our installation cost goal of $1/Watt for the entire system. The objective of this paper is to introduce the system concept and discuss the system components that are currently under development. (auth)

  12. Ribbon Si solar cells with efficiencies over 18% by hydrogenation of defects

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Seop; Yelundur, Vijay; Nakayashiki, Kenta; Rounsaville, Brian; Meemongkolkiat, Vichai; Rohatgi, Ajeet [University Center of Excellence for Photovoltaics Research and Education, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Gabor, Andrew M. [Evergreen Solar Inc., 259 Cedar Hill Street, Marlboro, MA 01752 (United States)

    2006-05-23

    We have fabricated 4cm{sup 2} solar cells on String Ribbon Si wafers and edge-defined film-fed grown (EFG) Si wafers with using a combination of laboratory and industrial processes. The highest efficiency on String Ribbon Si wafer is 17.8% with an open circuit voltage (V{sub oc}) of 620mV, a short circuit current density (J{sub sc}) of 36.8mA/cm{sup 2} and a fill factor (FF) of 0.78. The maximum efficiency on EFG Si is 18.2% with a V{sub oc} of 620mV, a J{sub sc} of 37.5mA/cm{sup 2} and a FF of 0.78. These are the most efficient ribbon Si devices made to date, demonstrating the high quality of the processed Si ribbon and its potential for industrial cells. Co-firing of SiN{sub x} and Al by rapid thermal processing was used to boost the minority carrier lifetime of bulk Si from 3-5{mu}s to 70-100{mu}s. Photolithography-defined front contacts were used to achieve low shading losses and low contact resistance with a good blue response. The effects of firing temperature and time were studied to understand the trade-off between hydrogen retention and Al-doped back surface field (Al-BSF) formation. Excellent bulk defect hydrogenation and high-quality thick Al-BSF formation was achieved in a very short time ({approx}1s) at firing temperatures of 740-750{sup o}C. It was found that the bulk lifetime decreases at annealing temperatures above 750{sup o}C or annealing time above 1s due to dissociation of hydrogenated defects. (author)

  13. The effects of hydrogen dilution on Voc in a-Si:H pin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Q.; Crandall, R.S.; Han, D.

    1997-07-01

    The authors study the effects of hydrogen dilution on the open circuit voltage of a-Si:H pin solar cells fabricated by rf glow discharge growth. They keep the p and n layers the same and only vary the i-layer properties. A normal a-Si:H i-layer, an H-diluted i-layer, and a thin H-diluted layer inserted between p and normal i layer are selected for this study. They measure the JV characteristics and the internal electric field distribution using a transient-null-current technique both in annealed and light soaked states. They find that hydrogen dilution does stabilize the Voc either in a bulk H-diluted i layer or in a thin layer between p and normal i layer after 100 hours Am1 sun light soaking. From dark IV measurement, both H-diluted cells show little change in current at voltage near Voc before and after light soaking; while the normal a-Si:H cell does show a noticeable change. Also the internal field measurements find a stronger electric field starting from p and i interface for both H-diluted cells compared to the normal a-Si:H cell. Furthermore, there are no measurable changes in the field profiles after 100 hour AM1 light-soaking for both H-diluted and normal a-Si cells. All these suggest that hydrogen dilution increases the field strength near p and i interface, which is the key that leads to a more stable Voc of H-diluted cells.

  14. Collisional thermalization of hydrogen and helium in solar-wind plasma.

    Science.gov (United States)

    Maruca, B A; Bale, S D; Sorriso-Valvo, L; Kasper, J C; Stevens, M L

    2013-12-13

    In situ observations of the solar wind frequently show the temperature of α particles (fully ionized helium) Tα to significantly differ from that of protons (ionized hydrogen) Tp. Many heating processes in the plasma act preferentially on α particles, even as collisions among ions act to gradually establish thermal equilibrium. Measurements from the Wind spacecraft's Faraday cups reveal that, at r=1.0  AU from the Sun, the observed values of the α-proton temperature ratio, θαp≡Tα/Tp, has a complex, bimodal distribution. This study applied a simple model for the radial evolution of θαp to these data to compute expected values of θαp at r=0.1  AU. These inferred θαp values have no trace of the bimodality seen in the θαp values measured at r=1.0  AU but are instead consistent with the actions of the known mechanisms for α-particle preferential heating. This result underscores the importance of collisional processes in the dynamics of the solar wind and suggests that similar mechanisms may lead to preferential α-particle heating in both slow and fast wind.

  15. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VII. Further Insights into the Chromosphere and Corona

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available In the liquid metallic hydrogen model of the Sun, the chromosphere is responsible for the capture of atomic hydrogen in the solar atmosphere and its eventual re-entry onto the photospheric surface (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Prog. Phys., 2013, v. 3, L15–L21. As for the corona, it represents a diffuse region containing both gaseous plasma and condensed matter with elevated electron affinity (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona. Prog. Phys., 2013, v. 3, L22–L25. Metallic hydrogen in the corona is thought to enable the continual harvest of electrons from the outer reaches of the Sun, thereby preserving the neutrality of the solar body. The rigid rotation of the corona is offered as the thirty-third line of evidence that the Sun is comprised of condensed matter. Within the context of the gaseous models of the Sun, a 100 km thick transition zone has been hypothesized to exist wherein temperatures increase dramatically from 104–106 K. Such extreme transitional temperatures are not reasonable given the trivial physical scale of the proposed transition zone, a region adopted to account for the ultra-violet emission lines of ions such as C IV, O IV, and Si IV. In this work, it will be argued that the transition zone does not exist. Rather, the intermediate ionization states observed in the solar atmosphere should be viewed as the result of the simultaneous transfer of protons and electrons onto condensed hydrogen structures, CHS. Line emissions from ions such as C IV, O IV, and Si IV are likely to be the result of condensation reactions, manifesting the involvement of species such as CH4, SiH4, H3O+ in the synthesis of CHS in the chromosphere. In addition, given the presence of a true solar surface at the level of the photosphere in the liquid metallic hydrogen model

  16. Impact of contamination on hydrogenated amorphous silicon thin films and solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Woerdenweber, Jan

    2011-09-26

    This thesis deals with atmospheric contamination and cross-contamination of boron (single-chamber process) of the intrinsic absorber layer (i-layer) of p-i-n thin film solar cells based on hydrogenated amorphous silicon. The atmospheric contaminations were introduced by means of intentional leaks. Hereby, the focus is on the influence of contamination species (oxygen and nitrogen), quantity of contamination (leak flow), source of contamination (leaks at chamber wall or in the process gas pipe), and plasma power on the properties of solar cells. Thereby, the minimum requirements for the purity of vacuum and process gas as well as leak conditions of the recipient and gas pipe system have been determined. Additionally, deposition regimes were developed, where the incorporation of impurities is significantly suppressed. For standard processes critical levels of nitrogen and oxygen contamination are determined to be {proportional_to} 4 x 10{sup 18} cm{sup -3} and {proportional_to} 2 x 10{sup 19} cm{sup -3}, respectively, for a leak situated at the chamber wall. Above these concentrations the solar cell efficiency deteriorates. In literature, incorporation of oxygen and nitrogen in doping configuration is assumed to be the reason for the cell deterioration. This assumption is supported by additional material studies of contaminated absorber layers done in this work. The difference in critical concentration is due to the higher doping efficiency of nitrogen compared to that for oxygen. Nevertheless, applying an air leak the critical concentrations of O and N are reached almost simultaneously since the incorporation probability of oxygen is about one order of magnitude higher compared to that for nitrogen. Applying a leak in the process gas pipe the critical oxygen contamination level increases to {proportional_to} 2 x 10{sup 20} cm{sup -3} whereas the critical nitrogen level remains unchanged compared to a chamber wall leak. Applying a deposition regime with a very high

  17. Towards efficient solar-to-hydrogen conversion: Fundamentals and recent progress in copper-based chalcogenide photocathodes

    Directory of Open Access Journals (Sweden)

    Chen Yubin

    2016-09-01

    Full Text Available Photoelectrochemical (PEC water splitting for hydrogen generation has been considered as a promising route to convert and store solar energy into chemical fuels. In terms of its large-scale application, seeking semiconductor photoelectrodes with high efficiency and good stability should be essential. Although an enormous number of materials have been explored for solar water splitting in the last several decades, challenges still remain for the practical application. P-type copper-based chalcogenides, such as Cu(In, GaSe2 and Cu2ZnSnS4, have shown impressive performance in photovoltaics due to narrow bandgaps, high absorption coefficients, and good carrier transport properties. The obtained high efficiencies in photovoltaics have promoted the utilization of these materials into the field of PEC water splitting. A comprehensive review on copper-based chalcogenides for solar-to-hydrogen conversion would help advance the research in this expanding area. This review will cover the physicochemical properties of copper-based chalco-genides, developments of various photocathodes, strategies to enhance the PEC activity and stability, introductions of tandem PEC cells, and finally, prospects on their potential for the practical solar-to-hydrogen conversion. We believe this review article can provide some insights of fundamentals and applications of copper-based chalco-genide thin films for PEC water splitting.

  18. Towards efficient solar-to-hydrogen conversion: Fundamentals and recent progress in copper-based chalcogenide photocathodes

    Science.gov (United States)

    Chen, Yubin; Feng, Xiaoyang; Liu, Maochang; Su, Jinzhan; Shen, Shaohua

    2016-09-01

    Photoelectrochemical (PEC) water splitting for hydrogen generation has been considered as a promising route to convert and store solar energy into chemical fuels. In terms of its large-scale application, seeking semiconductor photoelectrodes with high efficiency and good stability should be essential. Although an enormous number of materials have been explored for solar water splitting in the last several decades, challenges still remain for the practical application. P-type copper-based chalcogenides, such as Cu(In, Ga)Se2 and Cu2ZnSnS4, have shown impressive performance in photovoltaics due to narrow bandgaps, high absorption coefficients, and good carrier transport properties. The obtained high efficiencies in photovoltaics have promoted the utilization of these materials into the field of PEC water splitting. A comprehensive review on copper-based chalcogenides for solar-to-hydrogen conversion would help advance the research in this expanding area. This review will cover the physicochemical properties of copper-based chalco-genides, developments of various photocathodes, strategies to enhance the PEC activity and stability, introductions of tandem PEC cells, and finally, prospects on their potential for the practical solar-to-hydrogen conversion. We believe this review article can provide some insights of fundamentals and applications of copper-based chalco-genide thin films for PEC water splitting.

  19. Performance improvement of n-i-p μc-Si:H solar cells by gradient hydrogen dilution technique

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    High pressure radio frequency plasma enhanced chemical vapor deposition(RF-PECVD)process was adopted to investigate the effect of constant hydrogen dilution technique and gradient hydrogen dilu-tion technique on the structural evolution of intrinsic films and the performance of n-i-p microcrystal-line silicon solar cells.The experiment results demonstrated that the grain size and crystalline volume fraction along the growth direction of intrinsic films can be controlled and the performance of solar cells can be greatly improved by gradient hydrogen dilution technique.An initial active-area efficiency of 5.7%(Voc=0.47V,Jsc=20.2mA/cm2,FF=60%)for the μc-Si:H single-junction n-i-p solar cells and an initial active-area efficiency of 10.12%(Voc=1.2V,Jsc=12.05mA/cm2,FF=70%)for the a-Si:H/μc-Si:H tandem n-i-p solar cells has been achieved.

  20. Hydrogen passivation of defects and rapid thermal processing for high-efficiency silicon ribbon solar cells

    Science.gov (United States)

    Jeong, Ji-Weon

    2002-01-01

    The use of photovoltaic (PV) system offers a unique opportunity to solve the energy and the environmental problems simultaneously because solar energy is free and can be directly converted into electrical energy by solar cells without any undesirable impact on the environment. In spite of the many advantages, PV still accounts for less than 0.05% of the current U.S. energy portfolio. This is mainly because PV is 2-4 times more expensive than traditional energy sources. PV modules should cost about $1/W to produce electricity at a rate of 6¢/kWh and to compete with fossil fuels. Since Si material accounts for ˜40% of the cost of current Si PV modules, the use of low-cost Si substrate is critical for cost reduction. Edge-defined film-fed grown (EFG) Si ribbon is the focus as substrate materials for this research because it is one of the most promising for low-cost PV. However, as-grown EFG Si has a lot of impurities and crystal defects resulted from the Si feedstock and its growth system, which reduce the bulk lifetime of less than 3 ms. In this research, first, the requirements for achieving 16% efficiency have been established using computer model simulations. To improve the bulk lifetime, manufacturable P and Al gettering techniques are developed to remove the lifetime-killing impurities from the active to inactive device regions. PECVD SiN-induced hydrogen defect passivation is investigated and maximized through the fundamental understanding of the role of Al, the impact of RTP firing, and the difference between two PECVD SiN films. For low-cost contact formation, a novel RTP firing process is developed for high-quality screen-printed contacts and Al-BSF. Finally, a complete process sequence that involves the optimal conditions for defect passivation and contacts is developed to produce ˜16% efficiency on screen-printed EFG Si solar cells, which is the highest efficiency for any screen-printed Si ribbon solar cells to date.

  1. LOCAL INTERSTELLAR HYDROGEN'S DISAPPEARANCE AT 1 AU: FOUR YEARS OF IBEX IN THE RISING SOLAR CYCLE

    Energy Technology Data Exchange (ETDEWEB)

    Saul, Lukas; Rodriguez, Diego; Scheer, Juergen; Wurz, Peter [University of Bern, Bern (Switzerland); Bzowski, Maciej; Kubiak, Marzena; Sokol, Justina [Space Research Centre PAS, Warsaw (Poland); Fuselier, Stephen; McComas, Dave [Southwest Research Institute, San Antonio, TX (United States); Moebius, Eberhard [University of New Hampshire, Durham, NH (United States)

    2013-04-20

    NASA's Interstellar Boundary Explorer (IBEX) mission has recently opened a new window on the interstellar medium (ISM) by imaging neutral atoms. One ''bright'' feature in the sky is the interstellar wind flowing into the solar system. Composed of remnants of stellar explosions as well as primordial gas and plasma, the ISM is by no means uniform. The interaction of the local ISM with the solar wind shapes our heliospheric environment with hydrogen being the dominant component of the very local ISM. In this paper, we report on direct sampling of the neutral hydrogen of the local ISM over four years of IBEX observations. The hydrogen wind observed at 1 AU has decreased and nearly disappeared as the solar activity has increased over the last four years; the signal at 1 AU has dropped off in 2012 by a factor of {approx}8 to near background levels. The longitudinal offset has also increased with time presumably due to greater radiation pressure deflecting the interstellar wind. We present longitudinal and latitudinal arrival direction measurements of the bulk flow as measured over four years beginning at near solar minimum conditions. The H distribution we observe at 1 AU is expected to be different from that outside the heliopause due to ionization, photon pressure, gravity, and filtration by interactions with heliospheric plasma populations. These observations provide an important benchmark for modeling of the global heliospheric interaction. Based on these observations we suggest a further course of scientific action to observe neutral hydrogen over a full solar cycle with IBEX.

  2. A solar-powered microbial electrolysis cell with a platinum catalyst-free cathode to produce hydrogen.

    Science.gov (United States)

    Chae, Kyu-Jung; Choi, Mi-Jin; Kim, Kyoung-Yeol; Ajayi, Folusho F; Chang, In-Seop; Kim, In S

    2009-12-15

    This paper reports successful hydrogen evolution using a dye-sensitized solar cell (DSSC)-powered microbial electrolysis cell (MEC) without a Pt catalyst on the cathode, indicating a solution for the inherent drawbacks of conventional MECs, such as the need for an external bias and catalyst. DSSCs fabricated by assembling a ruthenium dye-loaded TiO(2) film and platinized FTO glass with an I(-)/I(3)(-) redox couple were demonstrated as an alternative bias (V(oc) = 0.65 V). Pt-loaded (0.3 mg Pt/cm(2)) electrodes with a Pt/C nanopowder showed relatively faster hydrogen production than the Pt-free electrodes, particularly at lower voltages. However, once the applied photovoltage exceeded a certain level (0.7 V), platinum did not have any additional effect on hydrogen evolution in the solar-powered MECs: hydrogen conversion efficiency was almost comparable for either the plain (71.3-77.0%) or Pt-loaded carbon felt (79.3-82.0%) at >0.7 V. In particular, the carbon nanopowder-coated electrode without Pt showed significantly enhanced performance compared to the plain electrode, which indicates efficient electrohydrogenesis, even without Pt by enhancing the surface area. As the applied photovoltage was increased, anodic methanogenesis decreased gradually, resulting in increasing hydrogen yield.

  3. Solar-hydrogen energy as an alternative energy source for mobile robots and the new-age car

    Science.gov (United States)

    Sulaiman, A.; Inambao, F.; Bright, G.

    2014-07-01

    The disastrous effects of climate change as witnessed in recent violent storms, and the stark reality that fossil fuels are not going to last forever, is certain to create renewed demands for alternative energy sources. One such alternative source, namely solar energy, although unreliable because of its dependence on available sunlight, can nevertheless be utilised to generate a secondary source of energy, namely hydrogen, which can be stored and thereby provide a constant and reliable source of energy. The only draw-back with hydrogen, though, is finding efficient means for its storage. This study demonstrates how this problem can be overcome by the use of metal hydrides which offers a very compact and safe way of storing hydrogen. It also provides a case study of how solar and hydrogen energy can be combined in an energy system to provide an efficient source of energy that can be applied for modern technologies such as a mobile robot. Hydrogen energy holds out the most promise amongst the various alternative energy sources, so much so that it is proving to be the energy source of choice for automobile manufacturers in their quest for alternative fuels to power their cars of the future.

  4. Direct thermal water splitting by concentrated solar radiation for hydrogen production. Phase O: Proof of concept experiment

    Science.gov (United States)

    Genequand, P.

    1980-01-01

    The direct production of hydrogen from water and solar energy concentrated into a high temperature aperture is described. A solar powered reactor able to dissociate water vapor and to separate the reaction product at high temperature was developed, and direct water splitting has been achieved in a laboratory reactor. Water vapor and radiative heating from a carbon dioxide laser are fed into the reactor, and water vapor enriched in hydrogen and water vapor enriched in oxygen are produced. The enriched water vapors are separated through a separation membrane, a small disc of zirconium dioxide heated to a range of 1800 k to 2800 k. To avoid water vapor condensation within the reactor, the total pressure within the reactor was limited to 0.15 torr. A few modifications would enable the reactor to be operated at an increased pressure of a few torrs. More substantial modifications would allow for a reaction pressure of 0.1 atmosphere.

  5. Resolution of the discrepancy between Balmer alpha emission rates, the solar Lyman beta flux, and models of geocoronal hydrogen concentration

    Science.gov (United States)

    Levasseur, A.-C.; Meier, R. R.; Tinsley, B. A.

    1976-01-01

    New satellite Balmer alpha measurements and solar Lyman beta flux and line profile measurements, together with new measurements of the zodiacal light intensity used in correcting both ground and satellite Balmer alpha measurements for the effects of the Fraunhofer line in the zodiacal light, have been used in a reevaluation of the long-standing discrepancy between ground-based Balmer alpha emission rates and other geocoronal hydrogen parameters. The solar Lyman beta line center flux is found to be (4.1 plus or minus 1.3) billion photons per sq cm per sec per angstrom at S(10.7) equals 110 and, together with a current hydrogen model which has 92,000 atoms per cu cm at 650 km for T(inf) equals 950 K, gives good agreement between calculated Balmer alpha emission rates and the ground-based and satellite measurements.

  6. Polarized Light from the Sun: Unification of the Corona and Analysis of the Second Solar Spectrum — Further Implications of a Liquid Metallic Hydrogen Solar Model

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2015-07-01

    Full Text Available In order to account for the slight polarization of the continuum towards the limb, propo- nents of the Standard Solar Model (SSM must have recourse to electron or hydrogen- based scattering of light, as no other mechanism is possible in a gaseous Sun. Con- versely, acceptance that the solar body is comprised of condensed matter opens up new avenues in the analysis of this problem, even if the photospheric surface itself is viewed as incapable of emitting polarized light. Thus, the increased disk polarization, from the center to the limb, can be explained by invoking the scattering of light by the at- mosphere above the photosphere. The former is reminiscent of mechanisms which are known to account for the polarization of sunlight in the atmosphere of the Earth. Within the context of the Liquid Metallic Hydrogen Solar Model (LMHSM, molecules and small particles, not electrons or hydrogen atoms as required by the SSM, would primarily act as scattering agents in regions also partially comprised of condensed hy- drogen structures (CHS. In addition, the well-known polarization which characterizes the K-corona would become a sign of emission polarization from an anisotropic source, without the need for scattering. In the LMHSM, the K, F, and T- coronas can be viewed as emissive and reflective manifestations of a single corona l entity adopting a radially anisotropic structure, while slowly cooling with altitude above the photosphere. The presence of “dust particles”, advanced by proponents of the SSM, would no longer be required to explain the F and T-corona, as a single cooling structure would account for the properties of the K, F, and T coronas. At the same time, the polarized “Second Solar Spectrum”, characterized by the dominance of certain elemental or ionic spectral lines and an abundance of molecular lines, could be explained in the LMHSM, by first invoking interface polarization and coordination of these species with condensed matter

  7. Hydrogenated TiO{sub 2} film for enhancing photovoltaic properties of solar cells and self-sensitized effect

    Energy Technology Data Exchange (ETDEWEB)

    He, Hongcai; Yang, Kui; Wang, Ning, E-mail: ning-wang@uestc.edu.cn; Luo, Feifei; Chen, Haijun [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2013-12-07

    Hydrogenated TiO{sub 2} film was obtained by annealing TiO{sub 2} film at 350 °C for 2 h with hydrogen, and TiO{sub 2} films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO{sub 2} film and pristine TiO{sub 2} film. Through optical and electrochemical characterization, the hydrogenated TiO{sub 2} film showed enhanced absorption and narrowed band gap, as well as reduced TiO{sub 2} surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO{sub 2} as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO{sub 2} film, which excited electrons injecting internal conduction band of TiO{sub 2} to generate more photocurrent.

  8. Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

    Directory of Open Access Journals (Sweden)

    Mason L. Terry

    2007-01-01

    Full Text Available The changes in open-circuit voltage (Voc, short-circuit current density (Jsc, and internal quantum efficiency (IQE of aLuminum induced crystallization, ion-assisted deposition (ALICIA polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation are examined. Voc improvements from 130 mV to 430 mV, Jsc improvements from 1.2 mA/cm2 to 11.3 mA/cm2, and peak IQE improvements from 16% to > 70% are achieved. A 1-second RTA plateau at 1000°C followed by hydrogenation increases the Jsc by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 μm due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and Voc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

  9. SOLAR RADIATION PRESSURE AND LOCAL INTERSTELLAR MEDIUM FLOW PARAMETERS FROM INTERSTELLAR BOUNDARY EXPLORER LOW ENERGY HYDROGEN MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Schwadron, N. A.; Moebius, E.; Kucharek, H.; Lee, M. A.; French, J. [University of New Hampshire, Durham, NH 03824 (United States); Saul, L.; Wurz, P. [University of Bern, 3012 Bern (Switzerland); Bzowski, M. [Space Research Centre of the Polish Academy of Sciences, Warsaw (Poland); Fuselier, S. A.; Livadiotis, G.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States); Frisch, P. [University of Chicago, Chicago, IL 60637 (United States); Gruntman, M. [University of Southern California, Los Angeles, CA 90089 (United States); Mueller, H. R. [Dartmouth College, Hanover, NH 03755 (United States)

    2013-10-01

    Neutral hydrogen atoms that travel into the heliosphere from the local interstellar medium (LISM) experience strong effects due to charge exchange and radiation pressure from resonant absorption and re-emission of Lyα. The radiation pressure roughly compensates for the solar gravity. As a result, interstellar hydrogen atoms move along trajectories that are quite different than those of heavier interstellar species such as helium and oxygen, which experience relatively weak radiation pressure. Charge exchange leads to the loss of primary neutrals from the LISM and the addition of new secondary neutrals from the heliosheath. IBEX observations show clear effects of radiation pressure in a large longitudinal shift in the peak of interstellar hydrogen compared with that of interstellar helium. Here, we compare results from the Lee et al. interstellar neutral model with IBEX-Lo hydrogen observations to describe the distribution of hydrogen near 1 AU and provide new estimates of the solar radiation pressure. We find over the period analyzed from 2009 to 2011 that radiation pressure divided by the gravitational force (μ) has increased slightly from μ = 0.94 ± 0.04 in 2009 to μ = 1.01 ± 0.05 in 2011. We have also derived the speed, temperature, source longitude, and latitude of the neutral H atoms and find that these parameters are roughly consistent with those of interstellar He, particularly when considering the filtration effects that act on H in the outer heliosheath. Thus, our analysis shows that over the period from 2009 to 2011, we observe signatures of neutral H consistent with the primary distribution of atoms from the LISM and a radiation pressure that increases in the early rise of solar activity.

  10. Experimental results of acetone hydrogenation on a heat exchanger type reactor for solar chemical heat pump; Solar chemical heat pump ni okeru acetone suisoka hanno netsu kaishu jikken

    Energy Technology Data Exchange (ETDEWEB)

    Takashima, T.; Doi, T.; Tanaka, T.; Ando, Y. [Electrotechnical Laboratory, Tsukuba (Japan); Miyahara, R.; Kamoshida, J. [Shibaura Institute of Technology, Tokyo (Japan)

    1996-10-27

    With the purpose of converting solar heat energy to industrial heat energy, an experiment of acetone hydrogenation was carried out using a heat exchanger type reactor that recovers heat generated by acetone hydrogenation, an exothermic reaction, and supplies it to an outside load. In the experiment, a pellet-like activated carbon-supported ruthenium catalyst was used for the acetone hydrogenation with hydrogen and acetone supplied to the catalyst layer at a space velocity of 400-1,200 or so. In the external pipe of the double-pipe type reactor, a heating medium oil was circulated in parallel with the flow of the reactant, with the heat of reaction recovered that was generated from the acetone hydrogenation. In this experiment, an 1wt%Ru/C catalyst and a 5wt%Ru/C catalyst were used so as to examine the effects of variation in the space velocity. As a result, from the viewpoint of recovering the heat of reaction, it was found desirable to increase the reaction speed by raising catalytic density and also to supply the reactant downstream inside the reaction pipe by increasing the space velocity. 1 ref., 6 figs., 1 tab.

  11. Doppler speeds of the hydrogen Lyman lines in solar flares from EVE

    CERN Document Server

    Brown, Stephen A; Labrosse, Nicolas

    2016-01-01

    The hydrogen Lyman lines provide important diagnostic information about the dynamics of the chromosphere, but there have been few systematic studies of their variability during flares. We investigate Doppler shifts in these lines in several flares, and use these to calculate plasma speeds. We use spectral data from the Multiple EUV Grating Spectrograph B (MEGS-B) detector of the Extreme-Ultraviolet Variability Experiment (EVE) instrument on the Solar Dynamics Observatory. MEGS-B obtains full-disk spectra of the Sun at a resolution of 0.1nm in the range 37-105 nm, which we analyse using three independent methods. The first method performs Gaussian fits to the lines, and compares the quiet-Sun centroids with the flaring ones to obtain the Doppler shifts. The second method uses cross-correlation to detect wavelength shifts between the quiet-Sun and flaring line profiles. The final method calculates the "center-of-mass" of the line profile, and compares the quiet-Sun and flaring centroids to obtain the shift. In ...

  12. Understanding and Enhancing the Photostability of Nanoporous Metal Oxide Thin Films for Solar Hydrogen Generation

    Science.gov (United States)

    Chitrada, Kalyan Chakravarthi

    Solar water splitting is an environmentally benign process which has received wide attention in the recent years as an alternate method for a clean and safe production of hydrogen. This process employs a semiconductor based photocatalyst, water, and sunlight to produce hydrogen. Metal-oxide based semiconductors are considered to be ideal photocatalytic materials because of their stability against photo-corrosion combined with relatively narrow energy band-gap, appropriately placed band edge positions with reference to oxygen and hydrogen energy levels, less scattering of charges due to wider valence band, high dielectric constant, natural abundance, and non-toxicity. In this dissertation, two metal oxide based semiconductors viz., iron (III) oxide and bismuth (III) oxide were investigated to understand and enhance their photo activity as photoanodes for solar water splitting application. Iron (III) oxide has a well suited band gap to capture solar spectrum but it suffers from inappropriately positioned band edges, recombination losses due to low electron mobility, and a small minority carrier diffusion length. However, it was hypothesized that the Iron (III) oxide might show interesting photoelectrochemical properties by alloying with 4f elements and shifting the conduction band minimum of the iron oxide favorably to more negative potentials. In the present study, a nanoporous iron oxide layer incorporated with Nd3+ and B3+ was synthesized by electrochemical anodization of a FeNdB alloy. The photoelectrochemical behavior of this oxide was compared with thermally oxidized FeNdB alloy and the iron oxides obtained by anodization and thermal oxidation of pure iron foil. Incorporation of Nd3+ and B3+ in the iron oxide showed a direct bandgap of 2.05 eV, an indirect bandgap of 1.9 eV and shifted the flatband potentials to --0.8 VAg/AgCl in 1 M KOH solution. The FeNdB oxide showed marginally better catalytic activity for the oxygen evolution reaction than pure iron oxide

  13. OBSERVATIONS OF THE INTERPLANETARY HYDROGEN DURING SOLAR CYCLES 23 AND 24. WHAT CAN WE DEDUCE ABOUT THE LOCAL INTERSTELLAR MEDIUM?

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Frédéric E.; Quémerais, Eric; Koutroumpa, Dimitra [Université Versailles St.-Quentin, Sorbonne Universités, UPMC Univ. Paris 06, CRNS/INSU, LATMOS-IPSL, 11 boulevard d' Alembert, 78280 Guyancourt (France); Katushkina, Olga; Izmodenov, Vladislav [Space Research Institute of Russian Academy of Sciences, Moscow (Russian Federation); Ben-Jaffel, Lotfi [UPMC Univ. Paris 06, UMR7095, Institut d' Astrophysique de Paris, F-75014, Paris (France); Harris, Walter M. [University of Arizona, Lunar and Planetary Laboratory, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Clarke, John [Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)

    2014-06-20

    Observations of interstellar helium atoms by the Interstellar Boundary Explorer (IBEX) spacecraft in 2009 reported a local interstellar medium (LISM) velocity vector different from the results of the Ulysses spacecraft between 1991 and 2002. The interplanetary hydrogen (IPH), a population of neutrals that fills the space between planets inside the heliosphere, carries the signatures of the LISM and its interaction with the solar wind. More than 40 yr of space-based studies of the backscattered solar Lyα emission from the IPH provided limited access to the velocity distribution, with the first temporal evolution map of the IPH line-shift during solar cycle 23. This work presents the results of the latest IPH observations made by the Hubble Space Telescope's Space Telescope Imaging Spectrograph during solar cycle 24. These results have been compiled with previous measurements, including data from the Solar Wind Anisotropies instrument on the Solar and Heliospheric Observatory. The whole set has been compared to physically realistic models to test both sets of LISM physical parameters as measured by Ulysses and IBEX, respectively. This comparison shows that the LISM velocity vector has not changed significantly since Ulysses measurements.

  14. Sacrificial hydrogen generation from aqueous triethanolamine with Eosin Y-sensitized Pt/TiO2 photocatalyst in UV, visible and solar light irradiation.

    Science.gov (United States)

    Chowdhury, Pankaj; Gomaa, Hassan; Ray, Ajay K

    2015-02-01

    In this paper, we have studied Eosin Y-sensitized sacrificial hydrogen generation with triethanolamine as electron donor in UV, visible, and solar light irradiation. Aeroxide TiO2 was loaded with platinum metal via solar photo-deposition method to reduce the electron hole recombination process. Photocatalytic sacrificial hydrogen generation was influenced by several factors such as platinum loading (wt%) on TiO2, solution pH, Eosin Y to Pt/TiO2 mass ratio, triethanolamine concentration, and light (UV, visible and solar) intensities. Detailed reaction mechanisms in visible and solar light irradiation were established. Oxidation of triethanolamine and formaldehyde formation was correlated with hydrogen generation in both visible and solar lights. Hydrogen generation kinetics followed a Langmuir-type isotherm with reaction rate constant and adsorption constant of 6.77×10(-6) mol min(-1) and 14.45 M(-1), respectively. Sacrificial hydrogen generation and charge recombination processes were studied as a function of light intensities. Apparent quantum yields (QYs) were compared for UV, visible, and solar light at four different light intensities. Highest QYs were attained at lower light intensity because of trivial charge recombination. At 30 mW cm(-2) we achieved QYs of 10.82%, 12.23% and 11.33% in UV, visible and solar light respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Annealing Kinetic Model Using Fast and Slow Metastable Defects for Hydrogenated-Amorphous-Silicon-Based Solar Cells

    Directory of Open Access Journals (Sweden)

    Seung Yeop Myong

    2007-01-01

    Full Text Available The two-component kinetic model employing “fast” and “slow” metastable defects for the annealing behaviors in pin-type hydrogenated-amorphous-silicon- (a-Si:H- based solar cells is simulated using a normalized fill factor. Reported annealing data on pin-type a-Si:H-based solar cells are revisited and fitted using the model to confirm its validity. It is verified that the two-component model is suitable for fitting the various experimental phenomena. In addition, the activation energy for annealing of the solar cells depends on the definition of the recovery time. From the thermally activated and high electric field annealing behaviors, the plausible microscopic mechanism on the defect removal process is discussed.

  16. Hydrogen-Enhanced Lunar Oxygen Extraction and Storage Using Only Solar Power

    Science.gov (United States)

    Burton, rodney; King, Darren

    2013-01-01

    The innovation consists of a thermodynamic system for extracting in situ oxygen vapor from lunar regolith using a solar photovoltaic power source in a reactor, a method for thermally insulating the reactor, a method for protecting the reactor internal components from oxidation by the extracted oxygen, a method for removing unwanted chemical species produced in the reactor from the oxygen vapor, a method for passively storing the oxygen, and a method for releasing high-purity oxygen from storage for lunar use. Lunar oxygen exists in various types of minerals, mostly silicates. The energy required to extract the oxygen from the minerals is 30 to 60 MJ/kg O. Using simple heating, the extraction rate depends on temperature. The minimum temperature is approximately 2,500 K, which is at the upper end of available oven temperatures. The oxygen is released from storage in a purified state, as needed, especially if for human consumption. This method extracts oxygen from regolith by treating the problem as a closed batch cycle system. The innovation works equally well in Earth or Lunar gravity fields, at low partial pressure of oxygen, and makes use of in situ regolith for system insulation. The innovation extracts oxygen from lunar regolith using a method similar to vacuum pyrolysis, but with hydrogen cover gas added stoichiometrically to react with the oxygen as it is produced by radiatively heating regolith to 2,500 K. The hydrogen flows over and through the heating element (HE), protecting it from released oxygen. The H2 O2 heat of reaction is regeneratively recovered to assist the heating process. Lunar regolith is loaded into a large-diameter, low-height pancake reactor powered by photovoltaic cells. The reactor lid contains a 2,500 K HE that radiates downward onto the regolith to heat it and extract oxygen, and is shielded above by a multi-layer tungsten radiation shield. Hydrogen cover gas percolates through the perforated tungsten shielding and HE, preventing

  17. [Autonomic neuropathies].

    Science.gov (United States)

    Siepmann, T; Penzlin, A I; Illigens, B M W

    2013-07-01

    Autonomic neuropathies are a heterogeneous group of diseases that involve damage of small peripheral autonomic Aδ- and C-fibers. Causes of autonomic nerve fiber damage are disorders such as diabetes mellitus and HIV-infection. Predominant symptoms of autonomic neuropathy are orthostatic hypotension, gastro-intestinal problems, urogenital dysfunction, and cardiac arrhythmia, which can severely impair the quality of life in affected patients. Furthermore, autonomic neuropathies can be induced by autoimmune diseases such as acute inflammatory demyelinating polyneuropathy, hereditary disorders such as the lysosomal storage disorder Fabry disease and hereditary sensory and autonomic neuropathies, as well as certain toxins and drugs.

  18. Hydrogen production from salt water by Marine blue green algae and solar radiation

    Science.gov (United States)

    Mitsui, A.; Rosner, D.; Kumazawa, S.; Barciela, S.; Phlips, E.

    1985-01-01

    Two marine bluegreen algae, Oscillatoria sp. Miami BG 7 and Synechococcus sp Miami 041511 have been selected as the result of over 10 years continuous and intensive effort of isolation, growth examination, and the screening of hydrogen photoproduction capability in this laboratory. Both strains photoproduced hydrogen for several days at high rates and a quantity of hydrogen was accumulated in a closed vessel. Overall hydrogen donor substance of the hydrogen photoproduction was found to be salt water. Using strain Miami BG 7, a two step method of hydrogen photoproduction from salt water was successfully developed and this was recycled several times over a one month period using both free cells and immobilized cells in both indoor and outdoor under natural sunlight. According to these experiments, a prototype floating hydrogen production system was designed for further development of the biosolar hydrogen production system.

  19. Hydrogen production from salt water by Marine blue green algae and solar radiation

    Science.gov (United States)

    Mitsui, A.; Rosner, D.; Kumazawa, S.; Barciela, S.; Phlips, E.

    1985-01-01

    Two marine bluegreen algae, Oscillatoria sp. Miami BG 7 and Synechococcus sp Miami 041511 have been selected as the result of over 10 years continuous and intensive effort of isolation, growth examination, and the screening of hydrogen photoproduction capability in this laboratory. Both strains photoproduced hydrogen for several days at high rates and a quantity of hydrogen was accumulated in a closed vessel. Overall hydrogen donor substance of the hydrogen photoproduction was found to be salt water. Using strain Miami BG 7, a two step method of hydrogen photoproduction from salt water was successfully developed and this was recycled several times over a one month period using both free cells and immobilized cells in both indoor and outdoor under natural sunlight. According to these experiments, a prototype floating hydrogen production system was designed for further development of the biosolar hydrogen production system.

  20. Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

    Science.gov (United States)

    Wu, Ming-Chung; Chen, Ching-Hsiang; Huang, Wei-Kang; Hsiao, Kai-Chi; Lin, Ting-Han; Chan, Shun-Hsiang; Wu, Po-Yeh; Lu, Chun-Fu; Chang, Yin-Hsuan; Lin, Tz-Feng; Hsu, Kai-Hsiang; Hsu, Jen-Fu; Lee, Kun-Mu; Shyue, Jing-Jong; Kordás, Krisztián; Su, Wei-Fang

    2017-01-01

    Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications. PMID:28102314

  1. Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf

    Science.gov (United States)

    Farihi, J.; Koester, D.; Zuckerman, B.; Vican, L.; Gänsicke, B. T.; Smith, N.; Walth, G.; Breedt, E.

    2016-12-01

    The Teff = 20 800 K white dwarf WD 1536+520 is shown to have broadly solar abundances of the major rock-forming elements O, Mg, Al, Si, Ca, and Fe, together with a strong relative depletion in the volatile elements C and S. In addition to the highest metal abundances observed to date, including log (O/He) = -3.4, the helium-dominated atmosphere has an exceptional hydrogen abundance at log (H/He) = -1.7. Within the uncertainties, the metal-to-metal ratios are consistent with the accretion of an H2O-rich and rocky parent body, an interpretation supported by the anomalously high trace hydrogen. The mixed atmosphere yields unusually short diffusion time-scales for a helium atmosphere white dwarf, of no more than a few hundred years, and equivalent to those in a much cooler, hydrogen-rich star. The overall heavy element abundances of the disrupted parent body deviate modestly from a bulk Earth pattern, and suggest the deposition of some core-like material. The total inferred accretion rate is 4.2 × 109 g s-1, and at least four times higher than for any white dwarf with a comparable diffusion time-scale. Notably, when accretion is exhausted in this system, both metals and hydrogen will become undetectable within roughly 300 Myr, thus supporting a scenario where the trace hydrogen is related to the ongoing accretion of planetary debris.

  2. Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure.

    Science.gov (United States)

    Wu, Ming-Chung; Chen, Ching-Hsiang; Huang, Wei-Kang; Hsiao, Kai-Chi; Lin, Ting-Han; Chan, Shun-Hsiang; Wu, Po-Yeh; Lu, Chun-Fu; Chang, Yin-Hsuan; Lin, Tz-Feng; Hsu, Kai-Hsiang; Hsu, Jen-Fu; Lee, Kun-Mu; Shyue, Jing-Jong; Kordás, Krisztián; Su, Wei-Fang

    2017-01-19

    Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti(3+) interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

  3. Improved Solar-Driven Photocatalytic Performance of Highly Crystalline Hydrogenated TiO2 Nanofibers with Core-Shell Structure

    Science.gov (United States)

    Wu, Ming-Chung; Chen, Ching-Hsiang; Huang, Wei-Kang; Hsiao, Kai-Chi; Lin, Ting-Han; Chan, Shun-Hsiang; Wu, Po-Yeh; Lu, Chun-Fu; Chang, Yin-Hsuan; Lin, Tz-Feng; Hsu, Kai-Hsiang; Hsu, Jen-Fu; Lee, Kun-Mu; Shyue, Jing-Jong; Kordás, Krisztián; Su, Wei-Fang

    2017-01-01

    Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

  4. A hydrogen-solar energy model for the Brazil: energy demand forecasting and economical aspects; Um modelo a hidrogenio-solar para o Brasil: projecoes de demanda de energia e aspectos economicos

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Samuel N.M. de [Univesidade Estadual de Campins (UNICAMP), SP (Brazil). Dept. de Energia; Lima, Lutero C. de; Mendes, Nathan [Uberlandia Univ., MG (Brazil). Dept. de Engenharia Mecanica

    1994-07-01

    This study proposes the introduction of hydrogen-solar renewable and clean fuel for replacing the present fossil fuels. The hydrogen can be produced by electric energy from using photovoltaic cells. The Brazil can be considered a suitable country for this system due to the high insulation in various areas of the country. Forecast for total energy demand, fossil energy, hydrogen prices and total cost of the project is performed by using mathematical modelling.

  5. Project Maghreb - Europe: Solar Production of Hydrogen. Phase I: Feasibility and opportunity study of the project; Projet Maghreb - Europe: Production d'hydrogene solaire. Phase I: Etude d'opportunite et de faisabilite du projet

    Energy Technology Data Exchange (ETDEWEB)

    Mahmah, Bouziane; Belhamel, Maiouf; Chader, Samira; M' Raoui, Abdelhamid; Harouadi, Farid; Etievant, Claude; Lechevalier, Steve; Cherigui, Abdel-Nasser

    2007-07-01

    During the 16th World Hydrogen Energy Conference which held on June 13-16, 2006, in Lyon (France), an important project appeared, the Maghreb-Europe Project for production and export of solar hydrogen, proposed in the Algiers Declaration of the hydrogen of origin renewable and directed by the researchers efforts of the Renewable Energies Development Center of Algiers (CDER) and members of the European company of Hydrogen Technologies (CETH). The present introductory communication exposes a scientific study on the appropriateness and the feasibility of the Project, as well as the objectives, missions and the fundamental elements for a scientific and technique accompaniment of this important project. (auth)

  6. Efficiency and stability aspects of CdS photoanode for solar hydrogen generation technology

    Science.gov (United States)

    Pareek, Alka; Gopalakrishnan, Arthi; Borse, Pramod H.

    2016-10-01

    Photoelectrochemical (PEC) cell based technology is expected to be one of the easiest green technologies to harness and to convert available solar energy into hydrogen [1]. Among the known systems of GaAs, Si, GaP and CdS- Cadmium sulphide is one of the best suited PEC materials that display a balance between its efficiency and stability. It has capability to absorb the visible light photons (E∼1.5eV - 3eV), and displays the band- energetics that suits for water-splitting reaction (H2O→H2+O2), that ultimately is based on the electronic and optical structure of the sulphides. However, the photo-induced dissolution of CdS in an electrolyte during its photo-illumination in PEC cell is its major drawback [2]. Though arsenides and phosphides show higher efficiency however CdS exhibits significant stability. In contrast though TiO2/ ZnO show good stability but CdS displays good optical response towards visible light photons as compared null response of titanate like systems. This necessitates one to identify the practical way to inhibit the photocorrosion in case of CdS photoanodes which is mainly facilitated due to interaction of photogenerated holes with CdS lattice. In past, Pt/ RuO2/ Ru modified CdS surface were found to control the unwanted photocorrosion [3]. Commercially, usage of such materials is un-economic option for any technological usage. The present work discusses that with advent of present day new synthetic routes how the dynamics of photo generated holes and electrons can be controlled to improve the stability and efficiency of the sulphide photoanodes, which in turn shows an an improvement in the performance and stability of the PEC cell for desirable technological applications.

  7. Hydrogen-doped Brookite TiO2 Nanobullets Array as a Novel Photoanode for Efficient Solar Water Splitting

    Science.gov (United States)

    Choi, Mingi; Lee, June Ho; Jang, Youn Jeong; Kim, Donghyung; Lee, Jae Sung; Jang, Hyun Myung; Yong, Kijung

    2016-01-01

    As a representative photocatalyst for photoelectrochemical solar water splitting, TiO2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO2, rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H+. which has the minimum formation energy among three states of hydrogen (H+. H0, and H−). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO2. PMID:27782198

  8. Ultrathin Co(Ni)-doped MoS2 nanosheets as catalytic promoters enabling efficient solar hydrogen production

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Ma; Jinquan Li; Changhua An; Juan Feng; Yuhua Chi; Junxue Liu; Jun Zhang

    2016-01-01

    The design of efficient artificial photosynthetic systems that harvest solar energy to drive the hydrogen evolution reaction via water reduction is of great importance from both the theoretical and practical viewpoints.Integrating appropriate co-catalyst promoters with strong light absorbing materials represents an ideal strategy to enhance the conversion efficiency of solar energy in hydrogen production.Herein,we report,for the first time,the synthesis of a class of unique hybrid structures consisting of ultrathin Co(Ni)-doped MoS2 nanosheets (co-catalyst promoter) intimately grown on semiconductor CdS nanorods (light absorber).The as-synthesized one-dimensional CdS@doped-MoS2 heterostructures exhibited very high photocatalytic activity (with a quantum yield of 17.3%) and stability towards H2 evolution from the photoreduction of water.Theoretical calculations revealed that Ni doping can increase the number of uncoordinated atoms at the edge sites of MoS2 nanosheets to promote electron transfer across the CdS/MoS2 interfaces as well as hydrogen reduction,leading to an efficient H2 evolution reaction.

  9. 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.

  10. Hydrogen-doped Brookite TiO2 Nanobullets Array as a Novel Photoanode for Efficient Solar Water Splitting

    Science.gov (United States)

    Choi, Mingi; Lee, June Ho; Jang, Youn Jeong; Kim, Donghyung; Lee, Jae Sung; Jang, Hyun Myung; Yong, Kijung

    2016-10-01

    As a representative photocatalyst for photoelectrochemical solar water splitting, TiO2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO2, rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H+. which has the minimum formation energy among three states of hydrogen (H+. H0, and H-). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO2.

  11. 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.

  12. Hydro Solar 21- A building energetic demand providing system based on renewable energies and hydrogen; Hydro Solar 21- Energias renovables e hidrogeno para el abastecimiento energetico de un edificio

    Energy Technology Data Exchange (ETDEWEB)

    Renilla Collado, R.; Ortega Izquierdo, M.

    2008-07-01

    Hydro Solar 21 is an energy innovation Project carried out in Burgos City to develop an energy production system based on renewable energies to satisfy light and air condition requirements of a restored building. Nocturnal light demand is satisfied with hydrogen consumption in fuel cells. This hydrogen is produced with an energy renewable system made up of two wind turbine generators and a photovoltaic system. The air conditioning demand is satisfied with an adsorption solar system which produces cold water using thermal solar energy. (Author) 8 refs.

  13. Automatic dosage of hydrogen peroxide in solar photo-Fenton plants: Development of a control strategy for efficiency enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Gomez, E. [Department of Chemical Engineering, University of Almeria, 04120 Almeria (Spain); CIESOL, Joint Centre of the University of Almeria-CIEMAT, 04120 Almeria (Spain); Moreno Ubeda, J.C. [Department of Language and Computation, University of Almeria, 04120 Almeria (Spain); Alvarez Hervas, J.D. [Department of Language and Computation, University of Almeria, 04120 Almeria (Spain); Department of Language and Computation, University of Sevilla, 41092 Sevilla (Spain); Casas Lopez, J.L.; Santos-Juanes Jorda, L. [Department of Chemical Engineering, University of Almeria, 04120 Almeria (Spain); CIESOL, Joint Centre of the University of Almeria-CIEMAT, 04120 Almeria (Spain); Sanchez Perez, J.A., E-mail: jsanchez@ual.es [Department of Chemical Engineering, University of Almeria, 04120 Almeria (Spain); CIESOL, Joint Centre of the University of Almeria-CIEMAT, 04120 Almeria (Spain)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer Dissolved oxygen monitoring is used for automatic dosage of H{sub 2}O{sub 2} in photo-Fenton. Black-Right-Pointing-Pointer PI with anti-windup minimises H{sub 2}O{sub 2} consumption. Black-Right-Pointing-Pointer The H{sub 2}O{sub 2} consumption was reduced up to 50% with respect to manual addition strategies. Black-Right-Pointing-Pointer Appropriate H{sub 2}O{sub 2} dosage is achieved by PI with anti-windup under disturbances. - Abstract: The solar photo-Fenton process is widely used for the elimination of pollutants in aqueous effluent and, as such, is amply cited in the literature. In this process, hydrogen peroxide represents the highest operational cost. Up until now, manual dosing of H{sub 2}O{sub 2} has led to low process performance. Consequently, there is a need to automate the hydrogen peroxide dosage for use in industrial applications. As it has been demonstrated that a relationship exists between dissolved oxygen (DO) concentration and hydrogen peroxide consumption, DO can be used as a variable in optimising the hydrogen peroxide dosage. For this purpose, a model was experimentally obtained linking the dynamic behaviour of DO to hydrogen peroxide consumption. Following this, a control system was developed based on this model. This control system - a proportional and integral controller (PI) with an anti-windup mechanism - has been tested experimentally. The assays were carried out in a pilot plant under sunlight conditions and with paracetamol used as the model pollutant. In comparison with non-assisted addition methods (a sole initial or continuous addition), a decrease of 50% in hydrogen peroxide consumption was achieved when the automatic controller was used, driving an economic saving and an improvement in process efficiency.

  14. Comparative study of the activity of nickel ferrites for solar hydrogen production by two-step thermochemical cycles

    Energy Technology Data Exchange (ETDEWEB)

    Fresno, Fernando [Solar Concentrating Systems, CIEMAT-PSA. Avda. Complutense, 22, 28040 Madrid (Spain); Yoshida, Tomoaki; Gokon, Nobuyuki; Kodama, Tatsuya [Department of Chemistry and Chemical Engineering and Center for Transdisciplinary Research, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Fernandez-Saavedra, Rocio [Chemistry Division, CIEMAT. Avda. Complutense, 22, 28040 Madrid (Spain)

    2010-08-15

    In this work, we compare the activity of unsupported and monoclinic zirconia - supported nickel ferrites, calcined at two different temperatures, for solar hydrogen production by two-step water-splitting thermochemical cycles at low thermal reduction temperature. Commercial nickel ferrite, both as-received and calcined in the laboratory, as well as laboratory made supported NiFe{sub 2}O{sub 4}, are employed for this purpose. The samples leading to higher hydrogen yields, averaged over three cycles, are those calcined at 700 C in each group (supported and unsupported) of materials. The comparison of the two groups shows that higher chemical yields are obtained with the supported ferrites due to better utilisation of the active material. Therefore, the highest activity is obtained with ZrO{sub 2}-supported NiFe{sub 2}O{sub 4} calcined at 700 C. (author)

  15. Hydrogenated indium oxide window layers for high-efficiency Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jäger, Timo, E-mail: timo.jaeger@empa.ch; Romanyuk, Yaroslav E.; Nishiwaki, Shiro; Bissig, Benjamin; Pianezzi, Fabian; Fuchs, Peter; Gretener, Christina; Tiwari, Ayodhya N. [Empa – Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Thin Films and Photovoltaics, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Döbeli, Max [ETH Zürich, Swiss Federal Institute of Technology, Laboratory of Ion Beam Physics, Otto-Stern-Weg 5, 8093 Zürich (Switzerland)

    2015-05-28

    High mobility hydrogenated indium oxide is investigated as a transparent contact for thin film Cu(In,Ga)Se{sub 2} (CIGS) solar cells. Hydrogen doping of In{sub 2}O{sub 3} thin films is achieved by injection of H{sub 2}O water vapor or H{sub 2} gas during the sputter process. As-deposited amorphous In{sub 2}O{sub 3}:H films exhibit a high electron mobility of ∼50 cm{sup 2}/Vs at room temperature. A bulk hydrogen concentration of ∼4 at. % was measured for both optimized H{sub 2}O and H{sub 2}-processed films, although the H{sub 2}O-derived film exhibits a doping gradient as detected by elastic recoil detection analysis. Amorphous IOH films are implemented as front contacts in CIGS based solar cells, and their performance is compared with the reference ZnO:Al electrodes. The most significant feature of IOH containing devices is an enhanced open circuit voltage (V{sub OC}) of ∼20 mV regardless of the doping approach, whereas the short circuit current and fill factor remain the same for the H{sub 2}O case or slightly decrease for H{sub 2}. The overall power conversion efficiency is improved from 15.7% to 16.2% by substituting ZnO:Al with IOH (H{sub 2}O) as front contacts. Finally, stability tests of non-encapsulated solar cells in dry air at 80 °C and constant illumination for 500 h demonstrate a higher stability for IOH-containing devices.

  16. Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie L.; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    -abundant alternatives are needed for large-scale use. We show that bioinspired molecular clusters based on molybdenum and sulphur evolve hydrogen at rates comparable to that of platinum. The incomplete cubane-like clusters (Mo3S 4) efficiently catalyse the evolution of hydrogen when coupled to a p-type Si semiconductor......The production of fuels from sunlight represents one of the main challenges in the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and although platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution, earth...

  17. Effective plasma hydrogen passivation of mc-Si solar cells after finishing contacts%多晶硅太阳电池的有效等离子体氢钝化

    Institute of Scientific and Technical Information of China (English)

    胡志华; 刘祖明; 陈庭金; 廖显伯; 廖华

    2002-01-01

    A simple equipment and process for hydrogen passivation of multicrystalline silicon (mc-Si) solar cells are reported in this work. Hydrogen plasma is generated by means of AC glow discharge in hydrogen atmosphere. Hydrogen passivation is carried out with three different groups of mc-Si solar cells after finishing contacts. The experimental results demonstrate that the photovoltaic performances of the solar cell samples have been improved after hydrogen plasma treatment, with a relative increase in conversion efficiency up to 10.6%.

  18. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The E-corona is the site of numerous emission lines associated with high ionization states (i.e. FeXIV-FeXXV. Modern gaseous models of the Sun require that these states are produced by atomic irradiation, requiring the sequential removal of electrons to infinity, without an associated electron acceptor. This can lead to computed temperatures in the corona which are unrealistic (i.e. ∼30–100 MK contrasted to solar core values of ∼16 MK. In order to understand the emission lines of the E-corona, it is vital to recognize that they are superimposed upon the K-corona, which produces a continuous spectrum, devoid of Fraunhofer lines, arising from this same region of the Sun. It has been advanced that the K-corona harbors self-luminous condensed matter (Robitaille P.M. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere II. Continuous Emission and Condensed Matter Within the Corona. Progr. Phys., 2013, v. 3, L8–L10; Robitaille P.M. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere III. Importance of Continuous Emission Spectra from Flares, Coronal Mass Ejections, Prominences, and Other Coronal Structures. Progr. Phys., 2013, v. 3, L11–L14. Condensed matter can possess elevated electron affinities which may strip nearby atoms of their electrons. Such a scenario accounts for the high ionization states observed in the corona: condensed matter acts to harness electrons, ensuring the electrical neutrality of the Sun, despite the flow of electrons and ions in the solar winds. Elevated ionization states reflect the presence of materials with high electron affinities in the corona, which is likely to be a form of metallic hydrogen, and does not translate into elevated temperatures in this region of the solar atmosphere. As a result, the many mechanisms advanced to account for coronal heating in the gaseous models of the Sun

  19. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VI. Helium in the Chromosphere

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available Molecular hydrogen and hydrides have recently been advanced as vital agents in the generation of emission spectra in the chromosphere. This is a result of the role they play in the formation of condensed hydrogen structures (CHS within the chromosphere (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Progr. Phys., 2013, v. 3, 15–21. Next to hydrogen, helium is perhaps the most intriguing component in this region of the Sun. Much like other elements, which combine with hydrogen to produce hydrides, helium can form the well-known helium hydride molecular ion, HeH+, and the excited neutral helium hydride molecule, HeH∗. While HeH+ is hypothesized to be a key cosmologicalmolecule, its possible presence in the Sun, and that of its excited neutral counterpart, has not been considered. Still, these hydrides are likely to play a role in the synthesis of CHS, as the He I and He II emission lines strongly suggest. In this regard, the study of helium emission spectra can provide insight into the condensed nature of the Sun, especially when considering the 10830 Å line associated with the 23P→2 3S triplet state transition. This line is strong in solar prominences and can be seen clearly on the disk. The excessive population of helium triplet states cannot be adequately explained using the gaseous models, since these states should be depopulated by collisional processes. Conversely, when He-based molecules are used to build CHS in a liquid metallic hydrogen model, an ever increasing population of the 23S and 23P states might be expected. The overpopulation of these triplet states leads to the conclusion that these emission lines are unlikely to be produced through random collisional or photon excitation, as required by the gaseous models. This provides a significant hurdle for these models. Thus, the strong 23P→2 3S lines and the overpopulation of the helium triplet

  20. High-energy, stable and recycled molecular solar thermal storage materials using AZO/graphene hybrids by optimizing hydrogen bonds

    Science.gov (United States)

    Luo, Wen; Feng, Yiyu; Qin, Chengqun; Li, Man; Li, Shipei; Cao, Chen; Long, Peng; Liu, Enzuo; Hu, Wenping; Yoshino, Katsumi; Feng, Wei

    2015-10-01

    An important method for establishing a high-energy, stable and recycled molecular solar heat system is by designing and preparing novel photo-isomerizable molecules with a high enthalpy and a long thermal life by controlling molecular interactions. A meta- and ortho-bis-substituted azobenzene chromophore (AZO) is covalently grafted onto reduced graphene oxide (RGO) for solar thermal storage materials. High grafting degree and close-packed molecules enable intermolecular hydrogen bonds (H-bonds) for both trans-(E) and cis-(Z) isomers of AZO on the surface of nanosheets, resulting in a dramatic increase in enthalpy and lifetime. The metastable Z-form of AZO on RGO is thermally stabilized with a half-life of 52 days by steric hindrance and intermolecular H-bonds calculated using density functional theory (DFT). The AZO-RGO fuel shows a high storage capacity of 138 Wh kg-1 by optimizing intermolecular H-bonds with a good cycling stability for 50 cycles induced by visible light at 520 nm. Our work opens up a new method for making advanced molecular solar thermal storage materials by tuning molecular interactions on a nano-template.An important method for establishing a high-energy, stable and recycled molecular solar heat system is by designing and preparing novel photo-isomerizable molecules with a high enthalpy and a long thermal life by controlling molecular interactions. A meta- and ortho-bis-substituted azobenzene chromophore (AZO) is covalently grafted onto reduced graphene oxide (RGO) for solar thermal storage materials. High grafting degree and close-packed molecules enable intermolecular hydrogen bonds (H-bonds) for both trans-(E) and cis-(Z) isomers of AZO on the surface of nanosheets, resulting in a dramatic increase in enthalpy and lifetime. The metastable Z-form of AZO on RGO is thermally stabilized with a half-life of 52 days by steric hindrance and intermolecular H-bonds calculated using density functional theory (DFT). The AZO-RGO fuel shows a high

  1. Potential of ITO nanoparticles formed by hydrogen treatment in PECVD for improved performance of back grid contact crystalline silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Sourav; Mitra, Suchismita; Dhar, Sukanta; Ghosh, Hemanta; Banerjee, Chandan, E-mail: chandanbanerjee74@gmail.com; Datta, Swapan K.; Saha, Hiranmoy

    2015-09-15

    Highlights: • Indium tin oxide (ITO) nanoparticles as back scatterers in c-Si solar cells. • ITO NP have comparatively low dissipative losses and tunable optical properties. • ITO NP formed by hydrogen plasma treatment on sputtered ITO film. • Enhanced absorption and carrier collection at longer wavelengths due to enhanced light trapping. - Abstract: This paper discusses the prospect of using indium tin oxide (ITO) nanoparticles as back scatterers in crystalline silicon solar cells instead of commonly used metal nanoparticles as ITO nanoparticles have comparatively low dissipative losses and tunable optical properties. ITO nanoparticles of ∼5–10 nm size is developed on the rear side of the solar cell by deposition of ∼5–10 nm thick ITO layer by DC magnetron sputtering followed by hydrogen treatment in PECVD. The silicon solar cell is fabricated in the laboratory using conventional method with grid metal contact at the back surface. Various characterizations like FESEM, TEM, AFM, XRD, EQE and IV characteristics are performed to analyze the morphology, chemical composition, optical characteristics and electrical performance of the device. ITO nanoparticles at the back surface of the solar cell significantly enhances the short circuit current, open circuit voltage and efficiency of the solar cell. These enhancements may be attributed to the increased absorption and carrier collection at longer wavelengths of solar spectrum due to enhanced light trapping by the ITO nanoparticles and surface passivation by the hydrogen treatment of the back surface.

  2. Study on the viability for the implantation of a hydrogen-solar-aeolian system for the state of Ceara, Brazil; Estudo de viabilidade para implantacao de um sistema a hidrogenio-solar-eolico para o estado do Ceara, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Sales, A.D.; Sacramento, E.M. do; Lima, L.C. de [Universidade Estadual do Ceara (UECE), Fortaleza, CE (Brazil)

    2008-07-01

    The state of the Ceara imports most of its consumed energy, configuring itself as a region eminently energy importer. However, the manufacture of its wind power Atlas demonstrated a high potential for the generation of electric energy originated from this renewable source. It is known, also, through studies, that this state possesses high potential for the exploitation of solar energy also for the generation of electric energy. A clean option to obtain hydrogen is the utilization of such renewable sources. This work presents results of the application of a model of solar-wind hydrogen energy for the Ceara state and variables such as population, gross intern product, energetic demand, energy imports, fossil fuel and hydrogen prices, income from hydrogen sale, and others parameters. The hydrogen will be produced from the sea water desalinisation, using solar and wind energies. The produced hydrogen eventually will be introduced in Ceara State through three scenarios which are one of, fast introduction, other of slow introduction and other of no introduction of hydrogen. (author)

  3. Photogating effect as a defect probe in hydrogenated nanocrystalline silicon solar cells

    NARCIS (Netherlands)

    Li, H. B. T.; Schropp, R.E.I.; Rubinelli, F.A.

    2010-01-01

    The measurement of the spectrally resolved collection efficiency is of great importance in solar cell characterization. Under standard conditions the bias light is a solar simulator or a light source with a similar broadband irradiation spectrum. When a colored blue or red bias light is used instead

  4. Autonomic neuropathies

    Science.gov (United States)

    Low, P. A.

    1998-01-01

    A limited autonomic neuropathy may underlie some unusual clinical syndromes, including the postural tachycardia syndrome, pseudo-obstruction syndrome, heat intolerance, and perhaps chronic fatigue syndrome. Antibodies to autonomic structures are common in diabetes, but their specificity is unknown. The presence of autonomic failure worsens prognosis in the diabetic state. Some autonomic neuropathies are treatable. Familial amyloid polyneuropathy may respond to liver transplantation. There are anecdotal reports of acute panautonomic neuropathy responding to intravenous gamma globulin. Orthostatic hypotension may respond to erythropoietin or midodrine.

  5. Recent advances in visible-light-responsive photocatalysts for hydrogen production and solar energy conversion--from semiconducting TiO2 to MOF/PCP photocatalysts.

    Science.gov (United States)

    Horiuchi, Yu; Toyao, Takashi; Takeuchi, Masato; Matsuoka, Masaya; Anpo, Masakazu

    2013-08-28

    The present perspective describes recent advances in visible-light-responsive photocatalysts intended to develop novel and efficient solar energy conversion technologies, including water splitting and photofuel cells. Water splitting is recognized as one of the most promising techniques to convert solar energy as a clean and abundant energy resource into chemical energy in the form of hydrogen. In recent years, increasing concern is directed to not only the development of new photocatalytic materials but also the importance of technologies to produce hydrogen and oxygen separately. Photofuel cells can convert solar energy into electrical energy by decomposing bio-related compounds and livestock waste as fuels. The advances of photocatalysts enabling these solar energy conversion technologies have been going on since the discovery of semiconducting titanium dioxide materials and have extended to organic-inorganic hybrid materials, such as metal-organic frameworks and porous coordination polymers (MOF/PCP).

  6. Stable, high-efficiency amorphous silicon solar cells with low hydrogen content. Annual subcontract report, 1 March 1991--31 January 1992

    Energy Technology Data Exchange (ETDEWEB)

    Fortmann, C.M.; Hegedus, S.S. [Institute of Energy Conversion, Newark, DE (United States)

    1992-12-01

    Results and conclusions obtained during a research program of the investigation of amorphous silicon and amorphous silicon based alloy materials and solar cells fabricated by photo-chemical vapor and glow discharge depositions are reported. Investigation of the effects of the hydrogen content in a-si:H i-layers in amorphous silicon solar cells show that cells with lowered hydrogen content i-layers are more stable. A classical thermodynamic formulation of the Staebler-Wronski effect has been developed for standard solar cell operating temperatures and illuminations. Methods have been developed to extract a lumped equivalent circuit from the current voltage characteristic of a single junction solar cell in order to predict its behavior in a multijunction device.

  7. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The chromosphere is the site of weak emission lines characterizing the flash spectrum observed for a few seconds during a total eclipse. This layer of the solar atmosphere is known to possess an opaque Hα emission and a great number of spicules, which can extend well above the photosphere. A stunning variety of hydrogen emission lines have been observed in this region. The production of these lines has provided the seventeenth line of evidence that the Sun is comprised of condensed matter (Robitaille P.M. Liquid Metallic Hydrogen II: A critical assessment of current and primordial helium levels in Sun. Progr. Phys., 2013, v. 2, 35–47. Contrary to the gaseous solar models, the simplest mechanism for the production of emission lines is the evaporation of excited atoms from condensed surfaces existing within the chromosphere, as found in spicules. This is reminiscent of the chemiluminescence which occurs during the condensation of silver clusters (Konig L., Rabin I., Schultze W., and Ertl G. Chemiluminescence in the Agglomeration of Metal Clusters. Science, v. 274, no. 5291, 1353–1355. The process associated with spicule formation is an exothermic one, requiring the transport of energy away from the site of condensation. As atoms leave localized surfaces, their electrons can occupy any energy level and, hence, a wide variety of emission lines are produced. In this regard, it is hypothesized that the presence of hydrides on the Sun can also facilitate hydrogen condensation in the chromosphere. The associated line emission from main group and transition elements constitutes the thirtieth line of evidence that the Sun is condensed matter. Condensation processes also help to explain why spicules manifest an apparently constant temperature over their entire length. Since the corona supports magnetic field lines, the random orientations associated with spicule formation suggests that the hydrogen condensates in the chromosphere are not metallic in

  8. Stand-alone power systems for the future: Optimal design, operation and control of solar-hydrogen energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Ulleberg, Oeystein

    1998-12-31

    This thesis gives a systematic review of the fundamentals of energy systems, the governing physical and chemical laws related to energy, inherent characteristics of energy system, and the availability of the earth`s energy. It shows clearly why solar-hydrogen systems are one of the most viable options for the future. The main subject discussed is the modelling of SAPS (Stand-Alone Power Systems), with focus on photovoltaic-hydrogen energy systems. Simulation models for a transient simulation program are developed for PV-H{sub 2} components, including models for photovoltaics, water electrolysis, hydrogen storage, fuel cells, and secondary batteries. A PV-H{sub 2} demonstration plant in Juelich, Germany, is studied as a reference plant and the models validated against data from this plant. Most of the models developed were found to be sufficiently accurate to perform short-term system simulations, while all were more than accurate enough to perform long-term simulations. Finally, the verified simulation models are used to find the optimal operation and control strategies of an existing PV-H{sub 2} system. The main conclusion is that the simulation methods can be successfully used to find optimal operation and control strategies for a system with fixed design, and similar methods could be used to find alternative system designs. 148 refs., 78 figs., 31 tabs.

  9. Novel functionality of organic 6,13-Pentacenequinone as a photocatalyst for hydrogen production under solar light.

    Science.gov (United States)

    Pandit, Vikram U; Arbuj, Sudhir S; Mulik, Uttam P; Kale, Bharat B

    2014-04-01

    6,13-Pentacenequinone (PQ), an intermediate for an organic semiconductor pentacene, was synthesized by single step solvent free solid state reaction at room temperature under ambient conditions which is hitherto unattempted. The phase purity has been confirmed by XRD and NMR. Optical study showed the absorption at 390 and 412 nm attributed to the π-π* and n-π* transitions, respectively. Cyclic voltammetry indicates the semiconducting nature of PQ having a band gap of 3 eV. The photoluminescence study revealed emissions at 408 and 432 nm. Considering the good thermal stability and absorption well within visible region, wisely, PQ has been used as a photocatalyst for the hydrogen production under solar light. Surprisingly we observed the utmost hydrogen evolution i.e. 4848 μmol/h/0.1 g (quantum efficiency 6.8%). The repeatability and reusability study confirmed the stability of the photocatalyst. The confirmation of the photocatalytic effect was also confirmed using methylene blue (MB) dye degradation under natural sunlight. The observed rate constant (Kapp) for photocatalytic MB degradation was 1.60 × 10(-2) min(-1). The use of an organic photocatalyst for hydrogen production has been demonstrated for the first time. This novel organic photocatalyst can also be explored for water splitting.

  10. Metal-encapsulated organolead halide perovskite photocathode for solar-driven hydrogen evolution in water

    OpenAIRE

    Crespo-Quesada, Micaela; Pazos-Outón, Luis M.; Warnan, Julien; Kuehnel, Moritz F; Friend, Richard H.; Reisner, Erwin

    2016-01-01

    Lead-halide perovskites have triggered the latest breakthrough in photovoltaic technology. Despite the great promise shown by these materials, their instability towards water even in the presence of low amounts of moisture makes them, a priori, unsuitable for their direct use as light harvesters in aqueous solution for the production of hydrogen through water splitting. Here, we present a simple method that enables their use in photoelectrocatalytic hydrogen evolution while immersed in an aqu...

  11. Solar hydrogen production with semiconductor metal oxides: new directions in experiment and theory

    DEFF Research Database (Denmark)

    Valdes, Alvaro; Brillet, Jeremie; Graetzel, Michael

    2012-01-01

    An overview of a collaborative experimental and theoretical effort toward efficient hydrogen production via photoelectrochemical splitting of water into di-hydrogen and di-oxygen is presented here. We present state-of-the-art experimental studies using hematite and TiO2 functionalized with gold n...... nanoparticles as photoanode materials, and theoretical studies on electro and photo-catalysis of water on a range of metal oxide semiconductor materials, including recently developed implementation of self-interaction corrected energy functionals....

  12. Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

    OpenAIRE

    Rahul Bhosale; Anand Kumar; Fares AlMomani; Ujjal Ghosh; Mohammad Saad Anis; Konstantinos Kakosimos; Rajesh Shende; Marc A. Rosen

    2016-01-01

    The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar) step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and wat...

  13. Liquid Metallic Hydrogen III. Intercalation and Lattice Exclusion Versus Gravitational Settling and Their Consequences Relative to Internal Structure, Surface Activity, and Solar Winds in the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-04-01

    Full Text Available Invocation of a liquid metallic hydrogen model (Robitaille P.M. Liquid Metallic Hydro- gen: A Building Block for the Liquid Sun. Progr. Phys ., 2011, v. 3, 60–74; Robitaille P.M. Liquid Metallic Hydrogen II: A Critical Assessment of Current and Primordial He- lium Levels in Sun. Progr. Phys ., 2013, v. 2, 35–47 brings with it a set of advantages for understanding solar physics which will always remain unavailable to the gaseous models. Liquids characteristically act as solvents and incorporate solutes within their often fleeting structural matrix. They possess widely varying solubility products and often reject the solute altogether. In that case, the solute becomes immiscible. “Lattice exclusion” can be invoked for atoms which attempt to incorporate themselves into liquid metallic hydrogen. In order to conserve the integrity of its conduction bands, it is antic- ipated that a graphite-like metallic hydrogen lattice should not permit incorporation of other elements into its in-plane hexagonal hydrogen framework. Based on the physics observed in the intercalation compounds of graphite, non-hydrogen atoms within liq- uid metallic hydrogen could reside between adjacent hexagonal proton planes. Conse- quently, the forces associated with solubility products and associated lattice exclusion envisioned in liquid metallic hydrogen for solutes would restrict gravitational settling. The hexagonal metallic hydrogen layered lattice could provide a powerful driving force for excluding heavier elements from the solar body. Herein lies a new exfoliative force to drive both surface activity (flares, coronal mass ejections, prominences and solar winds with serious consequences relative to the p–p reaction and CNO cycle in the Sun. At the same time, the idea that non-hydrogen atomic nuclei can exist between layers of metallic hydrogen leads to a fascinating array of possibilities with respect to nucleosyn- thesis. Powerful parallels can be drawn to the

  14. High-energy, stable and recycled molecular solar thermal storage materials using AZO/graphene hybrids by optimizing hydrogen bonds.

    Science.gov (United States)

    Luo, Wen; Feng, Yiyu; Qin, Chengqun; Li, Man; Li, Shipei; Cao, Chen; Long, Peng; Liu, Enzuo; Hu, Wenping; Yoshino, Katsumi; Feng, Wei

    2015-10-21

    An important method for establishing a high-energy, stable and recycled molecular solar heat system is by designing and preparing novel photo-isomerizable molecules with a high enthalpy and a long thermal life by controlling molecular interactions. A meta- and ortho-bis-substituted azobenzene chromophore (AZO) is covalently grafted onto reduced graphene oxide (RGO) for solar thermal storage materials. High grafting degree and close-packed molecules enable intermolecular hydrogen bonds (H-bonds) for both trans-(E) and cis-(Z) isomers of AZO on the surface of nanosheets, resulting in a dramatic increase in enthalpy and lifetime. The metastable Z-form of AZO on RGO is thermally stabilized with a half-life of 52 days by steric hindrance and intermolecular H-bonds calculated using density functional theory (DFT). The AZO-RGO fuel shows a high storage capacity of 138 Wh kg(-1) by optimizing intermolecular H-bonds with a good cycling stability for 50 cycles induced by visible light at 520 nm. Our work opens up a new method for making advanced molecular solar thermal storage materials by tuning molecular interactions on a nano-template.

  15. Solar conversion by concentration cells with hydrides. [Based on hydrogen pressure differential across protonic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Salomon, R.E.

    1979-01-01

    The efficiency of solar energy conversion in an electrochemical concentration cell which uses a metal hydride chemisorber is evaluated. It is shown that both constant volume and constant pressure cells can achieve the Carnot efficiency in principle. (SPH)

  16. Autonomic neuropathy

    DEFF Research Database (Denmark)

    Hilsted, J

    1983-01-01

    The diagnosis of autonomic neuropathy is often difficult to establish, since clinical symptoms generally appear late in the course of the disease, and may be non-specific. A number of recently developed quantifiable and reproducible autonomic nerve function tests are reviewed, with emphasis on th...

  17. Autonomic neuropathy

    DEFF Research Database (Denmark)

    Hilsted, J

    1980-01-01

    In order to elucidate the physiological significance of autonomic neuropathy in juvenile diabetics, cardiovascular, hormonal and metabolic functions have been investigated in three groups of juvenile diabetics: One group had no signs of neuropathy, one group had presumably slight autonomic...... neuropathy (reduced beat-to-beat variation in heart rate during hyperventilation) and one group had clinically severe autonomic neuropathy, defined by presence of orthostatic hypotension. In all three experimental situations we found sympathetic dysfunction causing cardiovascular and/or hormonal...... maladjustments in patients with autonomic neuropathy. Regarding metabolic functions we found normal responses to graded exercise and insulin-induced hypoglycemia in patients with autonomic neuropathy in spite of blunted catecholamine responses, suggesting increased sensitivity of glycogen stores and adipose...

  18. Hydrogen passivation of n+p and p+n heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, B.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    High-efficiency, heteroepitaxial (HE) InP solar cells, grown on GaAs, Si or Ge substrates, are desirable for their mechanically strong, light-weight and radiation-hard properties. However, dislocations, caused by lattice mismatch, currently limit the performance of the HE cells. This occurs through shunting paths across the active photovoltaic junction and by the formation of deep levels. In previous work we have demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of dislocations in specially designed HE InP test structures. In this work, we present the first report of successful hydrogen passivation in actual InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in HE n+n InP cell structures from as-grown values of approximately 10(exp 15)/cm(exp -3), down to 1-2 x 10(exp 13)/cm(exp -3). The deep levels in the p-type base region of the cell structure match those of our earlier p-type test structures, which were attributed to dislocations or related point defect complexes. All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. I-V analysis indicated a subsequent approximately 10 fold decrease in reverse leakage current at -1 volt reverse bias, and no change in the forward biased series resistance of the cell structure which indicates complete reactivation of the n+ emitter. Furthermore, electrochemical C-V profiling indicates greatly enhanced passivation depth, and hence hydrogen diffusion, for heteroepitaxial structures when compared with identically processed homoepitaxial n+p InP structures. An analysis of hydrogen diffusion in dislocated InP will be discussed, along with comparisons of passivation effectiveness for n+p versus p+n heteroepitaxial cell configurations. Preliminary hydrogen

  19. Exospheric hydrogen density distributions for equinox and summer solstice observed with TWINS1/2 during solar minimum

    Directory of Open Access Journals (Sweden)

    J. H. Zoennchen

    2013-03-01

    Full Text Available The Lyman-α Detectors (LAD on board the two TWINS 1/2-satellites allow for the simultaneous stereo imaging of the resonant emission glow of the H-geocorona from very different orbital positions. Terrestrial exospheric atomic hydrogen (H resonantly scatters solar Lyman-α (121.567 nm radiation. During the past solar minimum, relevant solar parameters that influence these emissions were quite stable. Here, we use simultaneous LAD1/2-observations from TWINS1 and TWINS2 between June 2008 and June 2010 to study seasonal variations in the H-geocorona. Data are combined to produce two datasets containing (summer solstice and (combined spring and fall equinox emissions. In the range from 3 to 10 Earth radii (RE, a three-dimensional (3-D mathematical model is used that allows for density asymmetries in longitude and latitude. At lower geocentric distances (RE, a best fitting r-dependent (Chamberlain, 1963-like model is adapted to enable extrapolation of our information to lower heights. We find that dawn and dusk H-geocoronal densities differ by up to a factor of 1.3 with higher densities on the dawn side. Also, noon densities are greater by up to a factor of 2 compared to the dawn and dusk densities. The density profiles are aligned well with the Earth–Sun line and there are clear density depletions over both poles that show additional seasonal effects. These solstice and equinox empirical fits can be used to determine H-geocoronal densities for any day of the year for solar minimum conditions.

  20. Simulation of a solar-hydrogen-fuel cell system: results for different locations in Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Torres, L.A.; Rodriguez, F.J.; Sebastian, P.J. [CIE-UNAM, Morelos (Mexico). Centro de Computo

    1998-12-31

    The authors report the results obtained from the simulation of a PV-hydrogen-fuel-cell (PVHFC) hybrid system for different locations in Mexico. The hybrid system consists of photovoltaic arrays coupled with an electrolyzer to produce hydrogen, a fuel cell which converts chemical energy (H{sub 2}) to electricity, a hydrogen storage, a battery storage system, and the load. In this kind of system, all components can be connected electrically in parallel. The voltage of the PV arrays the fuel cell must be high enough to charge the battery, and the voltage of the electrolyzer must be low enough for the battery to power it during periods of low insolation. The simulation is based on the electrical component models and variable insolation data depending on the location. (author)

  1. Metal-encapsulated organolead halide perovskite photocathode for solar-driven hydrogen evolution in water

    Science.gov (United States)

    Crespo-Quesada, Micaela; Pazos-Outón, Luis M.; Warnan, Julien; Kuehnel, Moritz F.; Friend, Richard H.; Reisner, Erwin

    2016-09-01

    Lead-halide perovskites have triggered the latest breakthrough in photovoltaic technology. Despite the great promise shown by these materials, their instability towards water even in the presence of low amounts of moisture makes them, a priori, unsuitable for their direct use as light harvesters in aqueous solution for the production of hydrogen through water splitting. Here, we present a simple method that enables their use in photoelectrocatalytic hydrogen evolution while immersed in an aqueous solution. Field's metal, a fusible InBiSn alloy, is used to efficiently protect the perovskite from water while simultaneously allowing the photogenerated electrons to reach a Pt hydrogen evolution catalyst. A record photocurrent density of -9.8 mA cm-2 at 0 V versus RHE with an onset potential as positive as 0.95+/-0.03 V versus RHE is obtained. The photoelectrodes show remarkable stability retaining more than 80% of their initial photocurrent for ~1 h under continuous illumination.

  2. Development of performance model and optimization strategy for standalone operation of CPV-hydrogen system utilizing multi-junction solar cell

    KAUST Repository

    Burhan, Muhammad

    2017-09-16

    Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.

  3. Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-04-01

    Full Text Available The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle and solar-to-fuel energy conversion efficiency (ηsolar−to−fuel attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar−to−fuel both increase with decreasing TH, due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore, the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance, in the case where TH = 2280 K, ηcycle = 24.4% and ηsolar−to−fuel = 29.5% (without heat recuperation, while ηcycle = 31.3% and ηsolar−to−fuel = 37.8% (with 40% heat recuperation.

  4. Gallex 1 measures hydrogen fusion neutrinos. A look into the solar furnace. Gallex 1 misst Wasserstoff-Fusions-Neutrinos. Blick in den Ofen der Sonne

    Energy Technology Data Exchange (ETDEWEB)

    Hintsches, E. (Max-Planck-Gesellschaft, Muenchen (Germany). Pressereferat)

    1992-09-25

    One of the central mysteries of science is about to be solved. The 'solar furnace' appears to function along the principles established by theoretical studies. The European gallium experiment 'Gallex' is the first to measure the main function of hydrogen fusion neutrinos. There is nothing to suggest neutrino mass. (orig.).

  5. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Shih, A. Y.; von Rosenvinge, T. T.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Cummings, A. C.

    2009-01-01

    We report the first observations of energetic neutral atoms (ENAs) from a solar flare/coronal mass ejection event. The observations were made during the December 5, 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on the STEREO A and B spacecraft. Within 1-2 hours of the flare onset, both LETs observed a sudden burst of 1.6 to 15 MeV protons arriving hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within +-10 degrees of the Sun. The derived emission profile at the Sun lasted for more than an hour and had a profile remarkably similar to the GOES soft X-ray profile. The observed arrival directions and energy spectrum argue strongly that the particle events atoms that were stripped of their electrons upon entering the LET sensor. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. We discuss possible origins for the production of ENAs in solar events, including charge-transfer reactions involving both flare and shock-accelerated protons. Assuming isotropic emission, we find that 2 x 10E28 ENAs escaped from the Sun in the upper hemisphere. Based on the 2.2 MeV gamma-ray emission observed by RHESSI in this event, and using measured and theoretical cross sections, we estimate that 3 x 10E31 ENAs with 1.8 - 5 MeV could be produced by protons accelerated in the flare. CME-driven shock acceleration is also a possible ENA source, but unfortunately there were no CME observations available from this event. Taking into account ENA losses, we conclude that the observed ENAs were most likely produced in the high corona at heliocentric distances 1.6 solar radii.

  6. High performance photoelectrochemical hydrogen generation and solar cells with a double type II heterojunction

    NARCIS (Netherlands)

    Lai, Lai-Hung; Gomulya, Widianta; Protesescu, Loredana; Kovalenko, Maksym V.; Loi, Maria A.

    2014-01-01

    We report on the fabrication of CdSe quantum dot (QD) sensitized electrodes by direct adsorption of colloidal QDs on mesoporous TiO2 followed by 3-mercaptopropionic acid (MPA) ligand exchange. High efficiency photoelectrochemical hydrogen generation is demonstrated by means of these electrodes. The

  7. Design and construction of a cascading pressure reactor prototype for solar-thermochemical hydrogen production

    Science.gov (United States)

    Ermanoski, Ivan; Grobbel, Johannes; Singh, Abhishek; Lapp, Justin; Brendelberger, Stefan; Roeb, Martin; Sattler, Christian; Whaley, Josh; McDaniel, Anthony; Siegel, Nathan P.

    2016-05-01

    Recent work regarding the efficiency maximization for solar thermochemical fuel production in two step cycles has led to the design of a new type of reactor—the cascading pressure reactor—in which the thermal reduction step of the cycle is completed in multiple stages, at successively lower pressures. This approach enables lower thermal reduction pressures than in single-staged reactors, and decreases required pump work, leading to increased solar to fuel efficiencies. Here we report on the design and construction of a prototype cascading pressure reactor and testing of some of the key components. We especially focus on the technical challenges particular to the design, and their solutions.

  8. The 100 kW space station. [regenerative fuel cells and nickel hydrogen and nickel cadmium batteries for solar arrays

    Science.gov (United States)

    Mckhann, G.

    1977-01-01

    Solar array power systems for the space construction base are discussed. Nickel cadmium and nickel hydrogen batteries are equally attractive relative to regenerative fuel cell systems at 5 years life. Further evaluation of energy storage system life (low orbit conditions) is required. Shuttle and solid polymer electrolyte fuel cell technology appears adequate; large units (approximately four times shuttle) are most appropriate and should be studied for a 100 KWe SCB system. A conservative NiH2 battery DOD (18.6%) was elected due to lack of test data and offers considerable improvement potential. Multiorbit load averaging and reserve capacity requirements limit nominal DOD to 30% to 50% maximum, independent of life considerations.

  9. Advanced nanoporous TiO2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application

    Science.gov (United States)

    An, Ha-Rim; Park, So Young; Kim, Hyeran; Lee, Che Yoon; Choi, Saehae; Lee, Soon Chang; Seo, Soonjoo; Park, Edmond Changkyun; Oh, You-Kwan; Song, Chan-Geun; Won, Jonghan; Kim, Youn Jung; Lee, Jouhahn; Lee, Hyun Uk; Lee, Young-Chul

    2016-07-01

    We report an effect involving hydrogen (H2)-plasma-treated nanoporous TiO2(H-TiO2) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO2(a-TiO2) without annealing process. Compared with the a-TiO2, the H-TiO2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H2 plasma is a simple strategy to fabricate H-TiO2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO2 showed strong ·OH free-radical generation on the TiO2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO2 120(H2-plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) — approximately four-times higher than those of the other photocatalysts (a-TiO2 and P25) — resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications.

  10. Economic evaluation of the solar thermal co-production of zinc, synthesis gas, and hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Steinfeld, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Spiewak, I. [EC Joint Research Centre (Spain)

    1999-08-01

    The use of concentrated solar energy for co-producing Zn and synthesis gas from Zn O and natural gas upgrades the calorific value of the initial reactants by 39% and, when compared to the traditional carbothermic reduction of Zn O, has the potential of reducing CO{sub 2} emissions by up to 78%. An economic assessment for an industrial thermochemical plant, 30 to 51 MW solar input, indicates that the cost of solar production of zinc ranges between 89-133 $/t (excluding the cost of Zn O feed and credit for pollution abatement), and thus might be competitive with conventional fossil-fuel-based processes at current fuel prices. The cost of solar H{sub 2}, produced by splitting water with zinc, is estimated to be in the range 0.10-0.14 $/kWh, and it is a favorable long term prospect once the cost of energy will account for the environmental externalities from fossil fuel burning such as the costs for CO{sub 2} mitigation and pollution abatement. (author) 1 fig., 2 tabs., 5 refs.

  11. Autonomic dysreflexia

    Science.gov (United States)

    ... most common cause of autonomic dysreflexia (AD) is spinal cord injury. The nervous system of people with AD over-responds to the types of stimulation that do not bother healthy people. Other causes ...

  12. Autonomous search

    CERN Document Server

    Hamadi, Youssef; Saubion, Frédéric

    2012-01-01

    Autonomous combinatorial search (AS) represents a new field in combinatorial problem solving. Its major standpoint and originality is that it considers that problem solvers must be capable of self-improvement operations. This is the first book dedicated to AS.

  13. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VIII. "Futile" Processes in the Chromosphere (Letters to Progress in Physics

    Directory of Open Access Journals (Sweden)

    Robitaille L.

    2014-01-01

    Full Text Available In the liquid metallic hydrogen solar model (LMHSM, the chr omosphere is the site of hydrogen condensation (P.M. Robitaille. The Liquid Metall ic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosp here. Progr. Phys. , 2013, v. 3, L15–L21. Line emission is associated with the di ssipation of energy from condensed hydrogen structures, CHS. Previously considere d reactions resulted in hy- drogen atom or cluster addition to the site of condensation. In this work, an additional mechanism is presented, wherein atomic or molecular specie s interact with CHS, but do not deposit hydrogen. These reactions channel heat away f rom CHS, enabling them to cool even more rapidly. As a result, this new class of proce sses could complement true hydrogen condensation reactions by providing an auxil iary mechanism for the re- moval of heat. Such ‘futile’ reactions lead to the formation of activated atoms, ions, or molecules and might contribute to line emission from such sp ecies. Evidence that com- plimentary ‘futile’ reactions might be important in the chr omosphere can be extracted from lineshape analysis.

  14. Hydrogen-Rich Syngas Production from Gasification and Pyrolysis of Solar Dried Sewage Sludge: Experimental and Modeling Investigations

    Science.gov (United States)

    Ghrib, Amina; Friaa, Athar; Ouerghi, Aymen; Naoui, Slim; Belayouni, Habib

    2017-01-01

    Solar dried sewage sludge (SS) conversion by pyrolysis and gasification processes has been performed, separately, using two laboratory-scale reactors, a fixed-bed pyrolyzer and a downdraft gasifier, to produce mainly hydrogen-rich syngas. Prior to SS conversion, solar drying has been conducted in order to reduce moisture content (up to 10%). SS characterization reveals that these biosolids could be appropriate materials for gaseous products production. The released gases from SS pyrolysis and gasification present relatively high heating values (up to 9.96 MJ/kg for pyrolysis and 8.02  9.96 MJ/kg for gasification) due to their high contents of H2 (up to 11 and 7 wt%, resp.) and CH4 (up to 17 and 5 wt%, resp.). The yields of combustible gases (H2 and CH4) show further increase with pyrolysis. Stoichiometric models of both pyrolysis and gasification reactions were determined based on the global biomass formula, CαHβOγNδSε, in order to assist in the products yields optimization. PMID:28856162

  15. Scattering effect of the high-index dielectric nanospheres for high performance hydrogenated amorphous silicon thin-film solar cells

    Science.gov (United States)

    Yang, Zhenhai; Gao, Pingqi; Zhang, Cheng; Li, Xiaofeng; Ye, Jichun

    2016-07-01

    Dielectric nanosphere arrays are considered as promising light-trapping designs with the capability of transforming the freely propagated sunlight into guided modes. This kinds of designs are especially beneficial to the ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells due to the advantages of using lossless material and easily scalable assembly. In this paper, we demonstrate numerically that the front-sided integration of high-index subwavelength titanium dioxide (TiO2) nanosphere arrays can significantly enhance the light absorption in 100 nm-thick a-Si:H thin films and thus the power conversion efficiencies (PCEs) of related solar cells. The main reason behind is firmly attributed to the strong scattering effect excited by TiO2 nanospheres in the whole waveband, which contributes to coupling the light into a-Si:H layer via two typical ways: 1) in the short-waveband, the forward scattering of TiO2 nanospheres excite the Mie resonance, which focuses the light into the surface of the a-Si:H layer and thus provides a leaky channel; 2) in the long-waveband, the transverse waveguided modes caused by powerful scattering effectively couple the light into almost the whole active layer. Moreover, the finite-element simulations demonstrate that photocurrent density (Jph) can be up to 15.01 mA/cm2, which is 48.76% higher than that of flat system.

  16. Hydrogen-Rich Syngas Production from Gasification and Pyrolysis of Solar Dried Sewage Sludge: Experimental and Modeling Investigations.

    Science.gov (United States)

    Ben Hassen Trabelsi, Aïda; Ghrib, Amina; Zaafouri, Kaouther; Friaa, Athar; Ouerghi, Aymen; Naoui, Slim; Belayouni, Habib

    2017-01-01

    Solar dried sewage sludge (SS) conversion by pyrolysis and gasification processes has been performed, separately, using two laboratory-scale reactors, a fixed-bed pyrolyzer and a downdraft gasifier, to produce mainly hydrogen-rich syngas. Prior to SS conversion, solar drying has been conducted in order to reduce moisture content (up to 10%). SS characterization reveals that these biosolids could be appropriate materials for gaseous products production. The released gases from SS pyrolysis and gasification present relatively high heating values (up to 9.96 MJ/kg for pyrolysis and 8.02  9.96 MJ/kg for gasification) due to their high contents of H2 (up to 11 and 7 wt%, resp.) and CH4 (up to 17 and 5 wt%, resp.). The yields of combustible gases (H2 and CH4) show further increase with pyrolysis. Stoichiometric models of both pyrolysis and gasification reactions were determined based on the global biomass formula, CαHβOγNδSε, in order to assist in the products yields optimization.

  17. A metal sulfide photocatalyst composed of ubiquitous elements for solar hydrogen production.

    Science.gov (United States)

    Shiga, Y; Umezawa, N; Srinivasan, N; Koyasu, S; Sakai, E; Miyauchi, M

    2016-06-14

    A visible-light-sensitive tin sulfide photocatalyst was designed based on a ubiquitous element strategy and density functional theory (DFT) calculations. Computational analysis suggested that tin monosulfide (SnS) would be more efficient than SnS2 as a photocathode for hydrogen production because of the low ionization potential and weak ionic character of SnS. To test this experimentally, nanoparticles of SnS were loaded onto a mesoporous electrode using a wet chemical method, and the bandgap of the synthesized SnS quantum dots was found to be tunable by adjusting the number of successive ionic layer adsorption and reaction (SILAR) cycles, which controls the magnitude of the quantum confinement effect. Efficient hydrogen production was achieved when the bandgap of SnS was wider than that of the bulk form.

  18. Renewable Bio-solar Hydrogen Production from Robust Oxygenic Phototrophs: The Second Generation

    Science.gov (United States)

    2015-01-22

    of Biotechnology , 2013. 166: p. 65– 75. 4) McNeely K., Kumaraswamy G.K., et al. (2014). Metabolic Switching of Central Carbon Metabolism in...Response to Nitrate: Application to Autofermentative Hydrogen Production in Cyanobacteria. Journal of Biotechnology , 182-183, 83-91. 5) Smith, PF, Kaplan...Waksman Institute of Microbiology and the Dept of Chemistry & Chem. Biology, Rutgers The State University of New Jersey, Piscataway, NJ 5. Telephone

  19. 太阳能-氢燃料电池系统性能研究%A Study on the Performance of Solar Hydrogen Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    孙建起; 耿亮; 郭晓飞; 杨郝楠; 李嘉欣

    2016-01-01

    氢燃料电池因其来源广泛、无污染、转换率高而成为能源领域关注的焦点.以质子交换膜氢燃料电池作为研究对象,通过对其发电过程原理分析及理论计算,阐明了太阳能-氢燃料电池在太阳能发电(光能原电能转换),电解水制取氢气(电能原氢能转换),燃料电池发电(氢能原电能转换)的整个能量转换过程.结果显示:质子交换膜氢燃料电池的转换率可达36.42%,实际制氢量与理论计算值误差小于5豫.%Hydrogen fuel cell has become the focus of attention in the field of energy because of its wide source, no pollution and high conversion rate. This paper, taking the proton exchange membrane fuel cell hydrogen as the object of study, expounds the energy conversion process of the solar hydrogen fuel cell in the solar electrical energy generation (solar energy to electric energy conversion), brine electrolysis to produce hydrogen (energy hydrogen energy conversion), fuel cell power generation (hydrogen electric en-ergy conversion) by the power generation process principle analysis and theoretical calculation. Then, through the experimental analysis of output characteristics and characteristics of proton exchange membrane, the result of the conversion rate of 36.42% and the actual production of hydrogen, with the theoretical cal-culated values with an error less than 5% are obtained by using HLD-QDC-1 type analyzer.

  20. Hydrogen production via steam-gasification of petroleum coke using concentrated solar power

    Energy Technology Data Exchange (ETDEWEB)

    Obladen, M.; Romey, I.; Schulz, A.; Schiffers, U.; Gunster, W.; Nobel, W.; Laerhoven, F. van; Herman, S.

    2005-07-01

    There is an increasing tendency in refinery's scope of refinery products towards light H2-enriched chemicals simultaneously resulting in a rising amount of heavy residues which would have to be disposed of. Gasifying these residues opens various ways for utilization, first of all the cost-effective production of H2 for the refining process and for future pilot markets like stationary and mobile fuel cell applications. This finally means bridging between conventional fossil fuel and future H2-based power supply. A strong consortium comprising University of Essen as coordinator, Siemens Power Generation, Continental Engineers and ECN from the Netherlands, ELCOGAS, the Spanish operator of Puertollano IGCC station as well as IST from Lisbon, carries out a new EU-funded three-year project called MIGREYD (Modular IGCC Concepts for In-Refinery Energy and Hydrogen Supply) together with the refinery company BP as subcontractor. Within this research and technical development (RTD) project an advanced modular highly efficient in-refinery energy and hydrogen supply system will be developed, using synergetic effects, which will be suitable for the production of power, process heat, hydrogen and other chemicals from residues, biomass and low-grade fossil fuels. By enhanced total plant efficiency and extensive CO2 reduction as well as saving resources by substituting high-grade fossil fuels, sustainable pollution control is possible. The main work topics in this project are. (Author)

  1. Time-dependent hydrogen ionisation in the solar chromosphere. I: Methods and first results

    CERN Document Server

    Wedemeyer-Boehm, J L S

    2006-01-01

    An approximate method for solving the rate equations for the hydrogen populations was extended and implemented in the three-dimensional radiation (magneto-)hydrodynamics code CO5BOLD. The method is based on a model atom with six energy levels and fixed radiative rates. It has been tested extensively in one-dimensional simulations. The extended method has been used to create a three-dimensional model that extends from the upper convection zone to the chromosphere. The ionisation degree of hydrogen in our time-dependent simulation is comparable to the corresponding equilibrium value up to 500 km above optical depth unity. Above this height, the non-equilibrium ionisation degree is fairly constant over time and space, and tends to be at a value set by hot propagating shock waves. The hydrogen level populations and electron density are much more constant than the corresponding values for statistical equilibrium, too. In contrast, the equilibrium ionisation degree varies by more than 20 orders of magnitude between...

  2. Data supporting the role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells.

    Science.gov (United States)

    Scuto, Andrea; Valenti, Luca; Pierro, Silvio; Foti, Marina; Gerardi, Cosimo; Battaglia, Anna; Lombardo, Salvatore

    2015-09-01

    Hydrogenated amorphous Si (a-Si:H) solar cells are strongly affected by the well known Staebler-Wronski effect. This is a worsening of solar cell performances under light soaking which results in a substantial loss of cell power conversion efficiency compared to time zero performance. It is believed not to be an extrinsic effect, but rather a basic phenomenon related to the nature of a-Si:H and to the stability and motion of H-related species in the a-Si:H lattice. This work has been designed in support of the research article entitled "Role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells" in Solar Energy Materials & Solar Cells (Scuto et al. [1]), which discusses an electrical method based on reverse bias stress to improve the solar cell parameters, and in particular the effect of temperature, electric field intensity and illumination level as a function of the stress time. Here we provide a further set of the obtained experimental data results.

  3. Development of Electrolysis System Powered by Solar-Cell Array to Supply Hydrogen Gas for Fuel-Cell Energy Resource Systems

    Science.gov (United States)

    Priambodo, Purnomo Sidi; Yusivar, Feri; Subiantoro, Aries; Gunawan, Ridwan

    2009-09-01

    The huge demand of energy worldwide and the depletion of fossil based energy, is a strong reason to rapidly develop any kind of renewable energy resources, which has economical advantages and zero pollution effect. One of the renewable energy technologies aimed in this paper is the generation of electric-energy based on fuel-cell technology, where the input hydrogen (H2) gas is supplied by electrolysis system powered by renewable energy system based on solar cell. In this paper, the authors explain the development of electrolysis system which is powered by solar cell array to supply hydrogen for fuel-cell system. The authors explain in detail how to design an efficient electrolysis system to obtain high ratio conversion of electric energy to hydrogen gas volume. It includes the explanation of the usage of multiple anodes with a single cathode for many solar cell inputs in a single electrolysis system. Hereinafter this is referred as multiple anode electrolysis system. This multiple anode electrolysis system makes the management of hydrogen gas becomes more efficient and effective by using only a single hydrogen gas storage system. This paper also explain the careful design of the resistance value of the electrolysis system to protect or avoid the solar cell panel to deliver excessive current to the electrolysis system which can cause damage on the solar cell panel. Moreover, the electrolyte volume detector is applied on the system as a tool to measure the electrolyte concentration to assure the system resistance is still in the allowed range. Further, the hydrogen gas produced by electrolysis system is stored into the gas storage which consists of silica-gel purifier, first stage low pressure gas bottle, vacuum pump, and second stage high pressure gas bottle. In the first step, the pump will vacuum the first bottle. The first bottle will collect the hydrogen from the electrolysis system through the silica gel to get rid of water vapor. When the first bottle

  4. Analytical and Experimental Studies of the Degradation in Hydrogenated Amorphous Silicon Solar Cells and Materials.

    Science.gov (United States)

    Yeung, Ping Fai

    1995-01-01

    An improved understanding of a-Si:H pin solar cells stability was obtained by studying light induced degradation in a-Si:H films and in devices. The current -voltage characteristics and the quantum efficiencies of a-Si:H pin solar cells were measured as a function of intrinsic layer thickness, bias light intensity and degradation condition. Photoconductivity measurements on device quality intrinsic a-Si:H thin film materials showed that the majority carrier (electron) mutau product degraded from 3times 10^{-7}rm cm ^2/V to 2times 10^{ -7}rm cm^2/V after 6 minutes of 50-Suns light illumination. Using a dual beam technique with steady white light and modulated monochromatic light, a degradation profile was detected in the degraded materials. These results suggest that inhomogeneous degradation may be important to understanding the stability of a-Si:H pin solar cells. An analytical model was developed for degradation in a-Si:H pin solar cells based on inhomogeneous degradation, which was used to explain the 'blue-dip' effect observed in the quantum efficiencies of degraded cells. A new method was developed to investigate the minority carrier (hole) diffusion length in device quality a-Si:H films as a function of degradation. This method uses the Schottky barrier structure to establish a depletion region, which can be controlled by the applied voltage and the bias light intensity. Modulated blue light is used to generate electron hole pairs near the ohmic contacts, and the holes diffuse across the neutral region to be collected. The modulated current is related to the diffusion length of the holes due to this current limiting hole transport. Comparing the results of this new technique to that of the Photocarrier Grating method, the electron drift mobility was found to degrade from rm 2.5cm^2/Vs to rm 0.15cm^2/Vs after 6 minutes of 50-Suns degradation.

  5. Contributions of solar wind and micrometeoroids to molecular hydrogen in the lunar exosphere

    Science.gov (United States)

    Hurley, Dana M.; Cook, Jason C.; Retherford, Kurt D.; Greathouse, Thomas; Gladstone, G. Randall; Mandt, Kathleen; Grava, Cesare; Kaufmann, David; Hendrix, Amanda; Feldman, Paul D.; Pryor, Wayne; Stickle, Angela; Killen, Rosemary M.; Stern, S. Alan

    2017-02-01

    We investigate the density and spatial distribution of the H2 exosphere of the Moon assuming various source mechanisms. Owing to its low mass, escape is non-negligible for H2. For high-energy source mechanisms, a high percentage of the released molecules escape lunar gravity. Thus, the H2 spatial distribution for high-energy release processes reflects the spatial distribution of the source. For low energy release mechanisms, the escape rate decreases and the H2 redistributes itself predominantly to reflect a thermally accommodated exosphere. However, a small dependence on the spatial distribution of the source is superimposed on the thermally accommodated distribution in model simulations, where density is locally enhanced near regions of higher source rate. For an exosphere accommodated to the local surface temperature, a source rate of 2.2 g s-1 is required to produce a steady state density at high latitude of 1200 cm-3. Greater source rates are required to produce the same density for more energetic release mechanisms. Physical sputtering by solar wind and direct delivery of H2 through micrometeoroid bombardment can be ruled out as mechanisms for producing and liberating H2 into the lunar exosphere. Chemical sputtering by the solar wind is the most plausible as a source mechanism and would require 10-50% of the solar wind H+ inventory to be converted to H2 to account for the observations.

  6. Velocity distributions of hydrogen atoms and hydroxyl radicals produced through solar photodissociation of water

    Science.gov (United States)

    Wu, C. Y. R.; Chen, F. Z.

    1993-01-01

    The velocity distributions of H and OH fragments produced through solar photodissociation of gaseous H2O molecules under collisionless conditions are presented. The calculations are carried out using: the most recently available absolute partial cross sections for the production of H and OH through photodissociation of H2O from its absorption onset at 1860 A down to 500 A; the newly available vibrational and rotational energy distributions of both the excited and ground state OH photofragments; the calculated cross sections for the total dissociation processes; and the integrated solar flux in 10 A increments from 500 to 1860 A in the continuum regions and the specific wavelength and flux at the bright solar lines. The calculated results show that the H atoms and the OH radicals produced exhibit multiple velocity groups. Since most current cometary modeling uses a single velocity of 20 km/sec associated with the photodissociation of H2O, the present results may be useful in interpreting the many peaks observed in the velocity distributions of the H Lyman alpha and H alpha of comets.

  7. Velocity distributions of hydrogen atoms and hydroxyl radicals produced through solar photodissociation of water

    Science.gov (United States)

    Wu, C. Y. R.; Chen, F. Z.

    1993-01-01

    The velocity distributions of H and OH fragments produced through solar photodissociation of gaseous H2O molecules under collisionless conditions are presented. The calculations are carried out using: the most recently available absolute partial cross sections for the production of H and OH through photodissociation of H2O from its absorption onset at 1860 A down to 500 A; the newly available vibrational and rotational energy distributions of both the excited and ground state OH photofragments; the calculated cross sections for the total dissociation processes; and the integrated solar flux in 10 A increments from 500 to 1860 A in the continuum regions and the specific wavelength and flux at the bright solar lines. The calculated results show that the H atoms and the OH radicals produced exhibit multiple velocity groups. Since most current cometary modeling uses a single velocity of 20 km/sec associated with the photodissociation of H2O, the present results may be useful in interpreting the many peaks observed in the velocity distributions of the H Lyman alpha and H alpha of comets.

  8. Forty Lines of Evidence for Condensed Matter — The Sun on Trial: Liquid Metallic Hydrogen as a Solar Building Block

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-10-01

    . Collectively, these lines of evidence provide a systematic challenge to the gaseous models of the Sun and expose the many hurdles faced by modern approaches. Observational astronomynand laboratory physics have remained unable to properly justify claims that the solar body must be gaseous. At the same time, clear signs of condensed matter interspersed with gaseous plasma in the chromosphere and corona have been regrettably dismissed. As such, it is hoped that this exposition will serve as an invitation to consider condensed matter, especially metallic hydrogen, when pondering the phase of the Sun. The Sun is a world so different from our own . . . However [relative to understanding its structure], one must not lose heart; over the past few years science has made a lot of progress, and those who come after us will not fail to make even more. Father Angelo Secchi, S.J., 1875 [1, p. 300, V. I]∗ 1 Introduction A long time ago, men like Gustav Kirchhoff, Johann Z¨ollner, William Thomson (Lord Kelvin, and James Jeans viewed the photosphere (or the solar body as existing in the liquid state [2, 3]. Despite their stature, scientists, since the days of Herbert Spencer and Angelo Secchi, slowly drifted towards ∗Translations from French were executed by the author. the concept that the Sun was a ball

  9. 非晶硅锗电池性能的调控研究%Modification to the performance of hydrogenated amorphous silicon germanium thin film solar cell

    Institute of Scientific and Technical Information of China (English)

    刘伯飞; 白立沙; 魏长春; 孙建; 侯国付; 赵颖; 张晓丹

    2013-01-01

    采用射频等离子体增强化学气相沉积技术,研究了非晶硅锗薄膜太阳电池。针对非晶硅锗薄膜材料的本身特性,通过调控硅锗合金中硅锗的比例,实现了对硅锗薄膜太阳电池中开路电压和短路电流密度的分别控制。借助于本征层硅锗材料帯隙梯度的设计,获得了可有效用于多结叠层电池中的非晶硅锗电池。%In this paper, we study hydrogenated amorphous silicon germanium thin film solar cells prepared by the radio frequency plasma-enhanced chemical vapor deposition. In the light of the inherent characteristics of hydrogenated amorphous silicon germanium mate-rial, the modulation of the germanium/silicon ratio in silicon germanium alloys can separately control open circuit voltage (Voc) and short circuit current density (Jsc) of a-SiGe:H thin film solar cells. By the structural design of band gap profiling in the amorphous silicon germanium intrinsic layer, hydrogenated amorphous silicon germanium thin film solar cells, which can be used efficiently as the component cell of multi-junction solar cells, are obtained.

  10. Mechanism insight into the effect of I/P buffer layer on the performance of NIP-type hydrogenated microcrystalline silicon solar cells

    Science.gov (United States)

    Bai, Lisha; Liu, Bofei; Zhao, Jing; Suo, Song; Hou, Guofu; Zhang, Dekun; Sun, Jian; Wei, Changchun; Zhao, Ying; Zhang, Xiaodan

    2015-05-01

    A simulation and experimental study on the effect of the buffer layer at the I/P interface on the performance of NIP-type hydrogenated microcrystalline silicon (μc-Si:H) single-junction solar cells is presented. Device-quality hydrogenated amorphous silicon (a-Si:H) material as a buffer layer at the I/P interface obviously improves the performance of NIP-type μc-Si:H single-junction solar cells. In addition to the well-known mechanism that an a-Si:H I/P buffer layer can reduce the recombination current density at I/P interfaces, the optically and electrically calibrated simulations and supporting experimental results in this study illustrate that the performance improvement also originates from the mitigation of the electric screening effect due to the reduced defect density at the I/P interfaces, which reinforces the bulk electric field. Integrating an optimized hydrogen profiling strategy and adding a-Si:H I/P buffer layer yielded an initial efficiency of 9.20% for μc-Si:H single-junction solar cells with an active area of 0.27 cm2. This study may provide new ideas of further improving the performance of NIP-type μc-Si:H single-junction solar cells by mitigating the electric screening effect.

  11. Hydrogen production by the solar-powered hybrid sulfur process: Analysis of the integration of the CSP and chemical plants in selected scenarios

    Science.gov (United States)

    Liberatore, Raffaele; Lanchi, Michela; Turchetti, Luca

    2016-05-01

    The Hybrid Sulfur (HyS) is a water splitting process for hydrogen production powered with high temperature nuclear heat and electric power; among the numerous thermo-chemical and thermo-electro-chemical cycles proposed in the literature, such cycle is considered to have a particularly high potential also if powered by renewable energy. SOL2HY2 (Solar to Hydrogen Hybrid Cycles) is a 3 year research project, co-funded by the Fuel Cells and Hydrogen Joint Undertaking (FCH JU). A significant part of the project activities are devoted to the analysis and optimization of the integration of the solar power plant with the chemical, hydrogen production plant. This work reports a part of the results obtained in such research activity. The analysis presented in this work builds on previous process simulations used to determine the energy requirements of the hydrogen production plant in terms of electric power, medium (550°C) temperature heat. For the supply of medium temperature (MT) heat, a parabolic trough CSP plant using molten salts as heat transfer and storage medium is considered. A central receiver CSP (Concentrated Solar Power) plant is considered to provide high temperature (HT) heat, which is only needed for sulfuric acid decomposition. Finally, electric power is provided by a power block included in the MT solar plant and/or drawn from the grid, depending on the scenario considered. In particular, the analysis presented here focuses on the medium temperature CSP plant, possibly combined with a power block. Different scenarios were analysed by considering plants with different combinations of geographical location and sizing criteria.

  12. Charge Transfer Dynamics in Semiconductor Quantum Dots Relevant to Solar Hydrogen Production

    Science.gov (United States)

    Krauss, Todd

    Artificial conversion of sunlight to chemical fuels has attracted attention for several decades as a potential source of clean, renewable energy. For example, in light-driven proton reduction to molecular hydrogen, a light-absorbing molecule (the photosensitizer) rapidly transfers a photoexcited electron to a catalyst for reducing protons. We recently found that CdSe quantum dots (QDs) and simple aqueous Ni2+ salts in the presence of a sacrificial electron donor form a highly efficient, active, and robust system for photochemical reduction of protons to molecular hydrogen. To understand why this system has such extraordinary catalytic behavior, ultrafast transient absorption (TA) spectroscopy studies of electron transfer (ET) processes from the QDs to the Ni catalysts were performed. CdSe QDs transfer photoexcited electrons to a Ni-dihydrolipoic acid (Ni-DHLA) catalyst complex extremely fast and with high efficiency. Even under high fluence, the relative fraction of TA signal due to ET remains well over 80%, and depopulation from exciton-exciton annihilation is minimal (6%). We also found that increasing QD size and/or shelling the core CdSe QDs with a shell of CdS slowed the ET rate, in agreement with the relative efficiency of photochemical H2 generation. The extremely fast ET provides a fundamental explanation for the exceptional photocatalytic H2 activity of the CdSe QD/Ni-DHLA system and guides new directions for further improvements.

  13. THE PHOENIX PROJECT: SHIFTING TO A SOLAR HYDROGEN ECONOMY BY 2020

    Directory of Open Access Journals (Sweden)

    HARRY BRAUN

    2008-07-01

    Full Text Available The most serious energy, economic and environmental problems are related to the use of fossil and nuclear fuels, which are rapidly diminishing and highly polluting, and many distinguished atmospheric chemists, including Dr. James Hanson at NASA, Dr. Steven Chu, the director of Lawrence Livermore Laboratory, and Professor Ralph Cicerone, president of the National Academy of Sciences have documented that climate changes are now occurring much faster than predicted just a few years ago. The methane hydrates in the oceans and the permafrost in vast areas of the Artic regions of Siberia, Alaska and Canada are now starting to rapidly melt, and given this could release 50 to 100 times more carbon into the atmosphere than is now generated from the burning of fossil fuels, humanity is rapidly approaching an exponential “tipping point” of no return. Given this sense of urgency, Hanson and others have warned that fossil fuels need to be phased-out by 2020 if irreversible damage to the earth’s climate and food production systems is to be avoided. The Phoenix Project plan seeks to do exactly that by mass-producing wind-powered hydrogen production systems and simply modifying all the existing vehicles and power plants to use the hydrogen made from the sun, wind and water.

  14. New Catalyst for HER and CO2 Hydrogenation for Solar Fuel Production

    DEFF Research Database (Denmark)

    Chorkendorff, Ib

    2013-01-01

    of a tandem dream device where the red part of the spectrum is utilized for solar fuel evolution, while the blue part is reserved for the more difficult oxygen evolution. Recently we have found that this system can be improved considerably using a np-Si systems [6] as recently described by the Nate Lewis......V positive of RHE the cell produce an incident photon to current efficiency (IPCE) of 50%. This work represents a substantial reduction in H2 evolution overpotential for non-Pt Si-photocathode operated in acidic solution. Further improvement in corrosion protection using several 100 nm of TiO2 [8...

  15. System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

    KAUST Repository

    Ehrhart, Brian D.

    2016-09-22

    The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas-gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered. © 2016 Hydrogen Energy Publications LLC.

  16. USE OF A LONG ENDURANCE SOLAR POWERED AUTONOMOUS UNDERWATER VEHICLE (SAUV II) TO MEASURE DISSOLVED OXYGEN CONCENTRATIONS IN GREENWICH BAY, RHODE ISLAND, USA

    Science.gov (United States)

    As hypoxic water masses increase worldwide in duration and extent due to coastal eutrophication, advanced technology water quality monitoring by autonomous vehicles can increase our capability to document and respond to these environmental perturbations. We evaluated the use of a...

  17. Harvesting solar light with crystalline carbon nitrides for efficient photocatalytic hydrogen evolution

    KAUST Repository

    Bhunia, Manas Kumar

    2014-08-14

    Described herein is the photocatalytic hydrogen evolution using crystalline carbon nitrides (CNs) obtained by supramolecular aggregation followed by ionic melt polycondensation (IMP) using melamine and 2,4,6-triaminopyrimidine as a dopant. The solid state NMR spectrum of 15N-enriched CN confirms the triazine as a building unit. Controlling the amount and arrangements of dopants in the CN structure can dramatically enhance the photocatalytic performance for H2 evolution. The polytriazine imide (PTI) exhibits the apparent quantum efficiency (AQE) of 15% at 400 nm. This method successfully enables a substantial amount of visible light to be harvested for H2 evolution, and provides a promising route for the rational design of a variety of highly active crystalline CN photocatalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Platinum containing amorphous hydrogenated carbon (a-C:H/Pt) thin films as selective solar absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Yung-Hsiang; Brahma, Sanjaya [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Tzeng, Y.H. [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Ting, Jyh-Ming, E-mail: jting@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan (China)

    2014-10-15

    We have investigated a double-cermet structured thin film in which an a-C:H thin film was used as an anti-reflective (AR) layer and two platinum-containing amorphous hydrogenated carbon (a-C:H/Pt) thin films were used as the double cermet layers. A reactive co-sputter deposition method was used to prepare both the anti-reflective and cermet layers. Effects of the target power and heat treatment were studied. The obtained films were characterized using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy. The optical absorptance and emittance of the as deposited and annealed films were determined using UV–vis-NIR spectroscopy. We show that the optical absorptance of the resulting double-cermet structured thin film is as high as 96% and remains to be 91% after heat treatment at 400 °C, indicating the thermal stability of the film.

  19. Solar Metal Sulfate-Ammonia Based Thermochemical Water Splitting Cycle for Hydrogen Production

    Science.gov (United States)

    Huang, Cunping (Inventor); T-Raissi, Ali (Inventor); Muradov, Nazim (Inventor)

    2014-01-01

    Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO.sub.4--NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)(4)SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)(4)SO3 into aqueous (NH3)(2)SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)(2)SO4 with metal oxide (e.g. ZnO) to form a slurry, heating the slurry of aqueous (NH4)(2)SO4 and ZnO(s) in the low temperature reactor to produce a gaseous mixture of NH3 and H2O and solid ZnSO4(s), heating solid ZnSO4 at a high temperature reactor to produce a gaseous mixture of SO2 and O2 and solid product ZnO, mixing the gaseous mixture of SO2 and O2 with an NH3 and H2O stream in an absorber to form aqueous (NH4)(2)SO3 solution and separate O2 for aqueous solution, recycling the resultant solution back to the photoreactor and sending ZnO to mix with aqueous (NH4)(2)SO4 solution to close the water splitting cycle wherein gaseous H2 and O2 are the only products output from the closed ZnSO4--NH3 cycle.

  20. Solar Photo Catalytic Hydrogen Production from water using a dual bed photosystem

    Energy Technology Data Exchange (ETDEWEB)

    Florida Solar Energy Center

    2003-03-30

    A body of work was performed in which the feasibility of photocatalytically decomposing water into its constituent elements using a dual bed, or modular photosystem, under solar radiation was investigated. The system envisioned consists of two modules, each consisting of a shallow, flat, sealed container, in which microscopic photocatalytic particles are immobilized. The photocatalysts absorb light, generating free electrons and lattice vacancy holes, which are capable of performing reductive and oxidative chemistry, respectively. The photocatalysts would be chosen as to whether they specifically promote H{sub 2} or O{sub 2} evolution in their respective containers. An aqueous solution containing a redox mediator is pumped between the two chambers in order to transfer electron equivalents from one reaction to the other.

  1. The effect of employing the p/i buffer layers and in-situ hydrogen treatment for transparent a-Si:H solar cells.

    Science.gov (United States)

    Lee, Da Jung; Yun, Sun Jin; Park, Min A; Lim, Jung Wook

    2014-05-01

    In this study, we describe the effects of various thicknesses of triple p/i buffer layers and hydrogen treatment on various performances in the fabrication of transparent a-Si:H solar cells. For the increment of buffer layer thickness, V(oc) increases steadily and J(sc) firstly increases and then decreases. The triple buffer layers also enhance the transmittance as well as conversion efficiency. For hydrogen plasma treatment, overall performances were enhanced with plasma power due to the passivation of dangling bonds at p/i interface. Therefore, the usage of triple buffer layers with proper treatment is beneficial to obtaining transparent a-Si:H solar cells with high quality.

  2. Structural defects caused by a rough substrate and their influence on the performance of hydrogenated nano-crystalline silicon n-i-p solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo B.T.; Franken, Ronald H.; Rath, Jatindra K.; Schropp, Ruud E.I. [Nanophotonics - Physics of Devices, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht (Netherlands)

    2009-03-15

    We present a cross-sectional transmission electron microscopy study of a set of hydrogenated nano-crystalline silicon n-i-p solar cells deposited by hot-wire chemical vapour deposition on Corning glass substrates coated with ZnO-covered Ag layers with various surface roughnesses. Strip-like structural defects (voids and low-density areas) are observed in the silicon layers originating from micro-valleys of Ag grains. A correlation between the opening angles of the textured surface and the appearance of these strips was found. We propose that in order to grow high-quality hydrogenated nano-crystalline silicon absorber layers for solar cell applications, the morphology of the Ag surface is a critical property, and the micro-valleys at the ZnO surface with an opening angle smaller than around 110 should be avoided. (author)

  3. Center for Autonomous Solar Power

    Science.gov (United States)

    2013-06-26

    2012 (Under Review) (Submitted on June 6, 2012) G. P. Pandey Graphene -Based All-Solid-State Supercapacitor with Ionic Liquid Gel Polymer Electrolyte ...Polyacrylonitrile and l-Ethyl-3-MethylimidazoIium Thiocyanate Based Gel Polymer Electrolyte for Solid-State Supercapacitors with Graphene Electrodes...to-roll fabrication line. On ultracapacitors, research has begun on electrodes and electrolytes to improve energy densities, and significant progress

  4. Development and simulation of a hydrogen production plant on a solar power tower; Entwicklung und Simulation einer Wasserstofferzeugungsanlage auf einem Solarturm

    Energy Technology Data Exchange (ETDEWEB)

    Saeck, Jan-Peter

    2012-08-29

    The purpose of the present project was to develop and qualify a test plant for thermochemical hydrogen production on a solar power tower and to create and validate a systems and control model as well as an operating strategy for this purpose. [German] Ziel der Arbeit war, eine Testanlage zur thermochemischen Wasserstofferzeugung auf einem Solarturmsystem zu entwickeln und zu qualifizieren, sowie ein System- und Regelungsmodell und eine Betriebsstrategie dafuer zu erstellen und zu validieren.

  5. Designing Efficient Solar-Driven Hydrogen Evolution Photocathodes Using Semitransparent MoQxCly(Q = S, Se) Catalysts on Si Micropyramids

    KAUST Repository

    Ding, Qi

    2015-09-21

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Silicon micropyramids with n+pp+ junctions are demonstrated to be efficient absorbers for integrated solar-driven hydrogen production systems enabling significant improvements in both photocurrent and onset potential. When conformally coated with MoSxCly, a catalyst that has excellent catalytic activity and high optical transparency, the highest photocurrent density for Si-based photocathodes with earth-abundant catalysts is achieved.

  6. Design of a Metal Oxide-Organic Framework (MoOF) Foam Microreactor: Solar-Induced Direct Pollutant Degradation and Hydrogen Generation.

    Science.gov (United States)

    Zhu, Liangliang; Fu Tan, Chuan; Gao, Minmin; Ho, Ghim Wei

    2015-12-16

    A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly.

  7. Nano-sized quaternary CuGa2In3S8 as an efficient photocatalyst for solar hydrogen production

    KAUST Repository

    Kandiel, Tarek

    2014-09-03

    The synthesis of quaternary metal sulfide (QMS) nanocrystals is challenging because of the difficulty to control their stoichiometry and phase structure. Herein, quaternary CuGa2In3S8 photocatalysts with a primary particle size of ≈4nm are synthesized using a facile hot-injection method by fine-tuning the sulfur source injection temperature and aging time. Characterization of the samples reveals that quaternary CuGa2In3S8 nanocrystals exhibit n-type semiconductor characteristics with a transition band gap of ≈1.8eV. Their flatband potential is located at -0.56V versus the standard hydrogen electrode at pH6.0 and is shifted cathodically by 0.75V in solutions with pH values greater than 12.0. Under optimized conditions, the 1.0wt% Ru-loaded CuGa2In3S8 photocatalyst exhibits a photocatalytic H2 evolution response up to 700nm and an apparent quantum efficiency of (6.9±0.5)% at 560nm. These results indicate clearly that QMS nanocrystals have great potential as nano-photocatalysts for solar H2 production. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Real Costs Assessment of Solar-Hydrogen and Some Fossil Fuels by means of a Combustion Analysis

    Directory of Open Access Journals (Sweden)

    Giovanni Nicoletti

    2016-01-01

    Full Text Available In order to compare solar-hydrogen and the most used fossil fuels, the evaluation of the “external” costs related to their use is required. These costs involve the environmental damage produced by the combustion reactions, the health problems caused by air pollution, the damage to land from fuel mining, and the environmental degradation linked to the global warming, the acid rains, and the water pollution. For each fuel, the global cost is determined as sum of the market price and of the correspondent external costs. In order to obtain a quantitative comparison, the quality of the different combustion reactions and the efficiency of the technologies employed in the specific application sector have to be considered adequately. At this purpose, an entropic index that considers the degree of irreversibility produced during the combustion process and the degradation of surroundings is introduced. Additionally, an environmental index that measures the pollutants released during the combustions is proposed. The combination of these indexes and the efficiency of the several technologies employed in four energy sectors have allowed the evaluation of the total costs, highlighting an economic scenario from which the real advantages concerning the exploitation of different energy carrier are determined.

  9. Enhancement of hydrogenated amorphous silicon solar cells with front-surface hexagonal plasmonic arrays from nanoscale lithography

    Science.gov (United States)

    Zhang, Chenlong; Gwamuri, Jephias; Cvetanovic, Sandra; Sadatgol, Mehdi; Guney, Durdu O.; Pearce, Joshua M.

    2017-07-01

    The study first uses numerical simulations of hexagonal triangle and sphere arrays to optimize the performance of hydrogenated amorphous silicon (a-Si:H) photovoltaic devices. The simulations indicated the potential for a sphere array to provide optical enhancement (OE) up to 7.4% compared to a standard cell using a nanosphere radius of 250 nm and silver film thickness of 50 nm. Next a detailed series of a-Si:H cells were fabricated and tested for quantum efficiency and characteristic and current-voltage (I-V) profiles using a solar simulator. Triangle and sphere array based cells, as well as the uncoated reference cells are analyzed and the results find that the simulation does not precisely predict the observed enhancement, but it forecasts a trend and can be used to guide fabrication. In general, the measured OE follows the simulated trend: (1) for triangular arrays no enhancement is observed and as the silver thickness increases the more degradation of the cell; (2) for annealed arrays both measured and simulated OE occur with the thinner silver thickness. Measured efficiency enhancement reached 20.2% and 10.9% for nanosphere diameter D = 500 nm, silver thicknesses h = 50 nm and 25 nm, respectively. These values, which surpass simulation results, indicate that this method is worth additional investigation.

  10. III-Nitride Membranes for Thermal Bio-Sensing and Solar Hydrogen Generation

    KAUST Repository

    Elafandy, Rami Tarek Mahmoud

    2017-09-01

    III-nitride nanostructures have generated tremendous scientific and technological interests in studying and engineering their low dimensional physics phenomena. Among these, 2D planar, free standing III-nitride nanomembranes are unrivalled in their scalability for high yield manufacture and can be mechanically manipulated. Due to the increase in their surface to volume ratio and the manifestation of quantum phenomena, these nanomembranes acquire unique physical properties. Furthermore, III-nitride membranes are chemically stable and biocompatible. Finally, nanomembranes are highly flexible and can follow curvilinear surfaces present in biological systems. However, being free-standing, requires especially new techniques for handling nanometers or micrometers thick membrane devices. Furthermore, effectively transferring these membrane devices to other substrates is not a direct process which requires the use of photoresists, solvents and/or elastomers. Finally, as the membranes are transferred, they need to be properly attached for subsequent device fabrications, which often includes spin coating and rinsing steps. These engineering complications have impeded the development of novel devices based on III-nitride membranes. In this thesis, we demonstrate the versatility of III-nitride membranes where we develop a thermal bio-sensor nanomembrane and solar energy photo-anode membrane. First, we present a novel preparation technique of nanomembranes with new characteristics; having no threading dislocation cores. We then perform optical characterization to reveal changes in their defect densities compared to the bulk crystal. We also study their mechanical properties where we successfully modulate their bandgap emission by 55 meV through various external compressive and tensile strain fields. Furthermore, we characterize the effect of phonon-boundary scattering on their thermal properties where we report a reduction of thermal conductivity from 130 to 9 W/mK. We employ

  11. System optimization of solar hydrogen energy system based on hydrogen production cost. 2; Suiso seizo cost wo hyoka shihyo to shita taiyo suiso energy system no saiteki sekkei. 2

    Energy Technology Data Exchange (ETDEWEB)

    Ota, D.; Yamagami, Y.; Tani, T. [Science University of Tokyo, Tokyo (Japan)

    1996-10-27

    In this paper, to evaluate the hydrogen production cost per unit volume, system optimization of solar hydrogen energy system is discussed. Based on the simulation of the I-V characteristics of amorphous Si (a-Si) photovoltaic array, the working point between the array and hydrogen generator was determined. The cost ratio of each design point was calculated. The optimum design points were 500 W/m{sup 2} for the single crystal Si system, and 600 W/m{sup 2} for the a-Si system. When the rating capacity of design point was constant, almost constant cost ratio was obtained independent of the type of photovoltaic cells. It was found that the photovoltaic cells can be fabricated in about 15% lower cost at maximum. It was also found that the optimum design point sifts to the lower insolation site due to reduction of the photovoltaic cell cost. Since the annual hydrogen generation quantity does not depend on the type of photovoltaic cells under the constant rating capacity of design point, hydrogen can be produced in lower cost by using photovoltaic cell of lower cost. 5 refs., 10 figs., 5 tabs.

  12. 太阳能光催化制氢研究进展%Photocatalytic Hydrogen Production Utilizing Solar Energy

    Institute of Scientific and Technical Information of China (English)

    温福宇; 杨金辉; 宗旭; 马艺; 徐倩; 马保军; 李灿

    2009-01-01

    Fossil fuels are non-renewable energy sources, combustion of fossil fuels cause a series of global environmental problems, such as global wanning by releasing of green-house gas CO_2, and a series of environmental pollution problems, etc. Development of clean, environmental friendly, and sustainable (or renewable) none fossil fuel energy sources has drawn much attention and becomes an important priority stratagem in many countries. Nowadays, it is generally accepted that solar energy will play an important role in the development of new energy sources since it is abundant, clean and especially renewable. Hydrogen is an ideal candidate for the replacement of the fossil fuels, because it features high combustion energy, and no environmental pollution. As a sustainable approach for new energy sources, photocatalytic hydrogen production utilizing solar energy is a promising strategy for the world. This article briefly review the recent advances in photocatalytic hydrogen production especially summarize the recent progress in photocatalytic H_2 evolution made in our group. The prospects for the development of highly efficient photocatalysts for H_2 production is also discussed.%由于化石燃料本身的不可持续性,以及燃烧化石燃料释放的大量CO_2产生的温室效应、环境污染等严重的全球性问题,构建洁净的、环境友好的、非化石燃料的可再生新能源体系,已经成为世界各国高度关注的焦点和重大战略.太阳能由于其取之不竭、洁净无污染、可再生等优点,必将在未来的新能源开发中占据举足轻重的地位.而氢能具有高燃烧值、燃烧产物是水无环境污染等优点,因此,利用自然界丰富的太阳能光催化制氢作为可持续发展的新能源途径之一,正日益受到国际社会的高度关注.本文简要综述了近年来这一研究领域的一些重要进展,总结了本课题组在半导体光催化制氢研究方面所取得的最新结果,并对太

  13. Nature's Autonomous Oscillators

    Science.gov (United States)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  14. The relationship between the boron dipyrromethene (BODIPY) structure and the effectiveness of homogeneous and heterogeneous solar hydrogen-generating systems as well as DSSCs.

    Science.gov (United States)

    Luo, Geng-Geng; Lu, Hui; Zhang, Xiao-Long; Dai, Jing-Cao; Wu, Ji-Huai; Wu, Jia-Jia

    2015-04-21

    A series of boron dipyrromethene (BODIPY) dyes (B1–B5) having H atoms at 2,6-positions or heavy-atom I at 2-/2,6-positions, and an ortho- or a para-COOH substituted phenyl moiety at the 8-position on the BODIPY core were synthesized and characterized. These organic dyes were applied for investigating the relationship between the BODIPY structure and the effectiveness of homogeneous and heterogeneous visible-light-driven hydrogen production as well as dye-sensitized solar cells (DSSCs). For the homogeneous photocatalytic hydrogen production systems with a cobaloxime catalyst, the efficiency of hydrogen production could be tuned by substituting with heavy atoms and varying carboxyl group orientations of BODIPYs. As a result, B5 containing two I atoms and an ortho-COOH anchoring group was the most active one (TONs = 197). The activity of hydrogen generation followed the order B5 > B3 > B2 > B1 = B4 = 0. An interesting “ortho-position effect” was observed in the present homogeneous systems, i.e., substitution groups were located at the ortho-position and higher hydrogen production activities were obtained. For the heterogeneous hydrogen production systems with a platinized TiO2 catalyst, the effectiveness of hydrogen evolution was highly influenced by the intersystem crossing efficiency, molar absorptivity and positions of the anchoring group of dyes. Thus, B3 having two core iodine atoms and a para-COOH group with TONs of 70 excelled other BODIPYs and the TONs of hydrogen generation showed the trend of B3 > B5 > B2 > B1 = B4 = 0. The results demonstrate that the present photocatalytic H2 production proceeds with higher efficiency and stability in the homogeneity than in the heterogeneity. In the case of DSSCs, the overall cell performance of BODIPY chromophores was highly dependent on both the absence or the presence of iodine atoms on the BODIPY core and –COOH anchoring positions. The B1–TiO2 system showed the best cell performance, because the most

  15. Decoration of PbS nanoparticles on Al-doped ZnO nanorod array thin film with hydrogen treatment as a photoelectrode for solar water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Hsiung; Chen, Chao-Hong [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chen, Dong-Hwang, E-mail: chendh@mail.ncku.edu.tw [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-03-25

    Highlights: ► AZO nanorod array thin film is used as a photoanode for solar water splitting. ► Hydrogen treatment and sensitization by PbS nanoparticles enhance photocurrent. ► A novel ITO/FTO-free composite photoelectrode is developed. ► The pre-fabrication and use of an extra TCO thin film substrate is unnecessary. -- Abstract: Al-doped ZnO (AZO) nanorod arrays thin film with hydrogen treatment is directly used as a photoelectrode for solar water splitting without an extra transparent conducting oxide (TCO) thin film because it possesses the functions of TCO thin film and photoactive 1-dimensional nanostructured semiconductor simultaneously. To enhance the absorption in the visible region, PbS nanoparticles decorated the AZO nanorods via successive ionic layer adsorption and reaction route. The PbS nanoparticles have a face-centered cubic structure and their decoration does not destroy the 1-dimensional morphology of AZO nanorod arrays. With increasing the cycle number of PbS nanoparticles decoration, the grain size and loading of PbS nanoparticles become larger gradually which leads to lower energy bandgap and stronger absorption. A maximum photocurrent density of 1.65 mW cm{sup −2} is obtained when the cycle number is 20, which is much higher than those without PbS nanoparticles sensitization or hydrogen treatment. This demonstrates that the AZO nanorod array thin film with hydrogen treatment can be directly used as a photoelectrode without an extra TCO thin film. Because the use of expensive metals can be avoided and the pre-fabrication of TCO thin film substrate is necessary no more, the fabrication of such a composite photoelectrode becomes simple and low-cost. So, it has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

  16. Cold-starting portable microenergy system. Autonomous fuel cell system using sodium borohydride as an energy source; Kaltstartfaehiges portables Mikroenergiesystem. Autarkes BZ-System mit Natriumborhydrid als Energietraeger

    Energy Technology Data Exchange (ETDEWEB)

    Groos, Ulf; Koch, Wolfgang [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany)

    2012-10-15

    A project consortium led by Fraunhofer-Institut fuer Solare Energiesysteme ISE developed an autonomous micro energy system (AMES) with an output of 100 W{sub el} as a charging station for applications in emergency medicine. The system is designed for a wide temperature range of -15 to +50 degC during startup, operation, and shutoff. The cold starting fuel cell system is in accordance with current standards and is suited for serial production. It can be operated with common hydrogen stores, e.g. gas flasks or metal hydrides, or else with a specially developed hydrogen generator based on sodium borohydride. (orig.)

  17. Autonomous Airship

    Directory of Open Access Journals (Sweden)

    Martin POSPÍŠILÍK

    2009-06-01

    Full Text Available This paper describes a project of attaching the autonomous monitoring system to a small helium airship. The airship is capable of independent operating inside a closed hall, being driven by means of ultrasonic detectors. It is accommodated to carry different monitoring units providing students with the opportunity to process various experiments and measurements. In the first experiment, the airship will carry WiFi router, camera and IP Relay by means of which the pertinent control of the airship through external web interface is enabled, independently on the ultrasonic detecting system.

  18. Autonomous Search

    CERN Document Server

    Hamadi, Youssef; Saubion, Frédéric

    2012-01-01

    Decades of innovations in combinatorial problem solving have produced better and more complex algorithms. These new methods are better since they can solve larger problems and address new application domains. They are also more complex which means that they are hard to reproduce and often harder to fine-tune to the peculiarities of a given problem. This last point has created a paradox where efficient tools are out of reach of practitioners. Autonomous search (AS) represents a new research field defined to precisely address the above challenge. Its major strength and originality consist in the

  19. Solar energy engineering

    Energy Technology Data Exchange (ETDEWEB)

    Sayigh, A.A.M. (ed.)

    1977-01-01

    The scope and advantages of solar energy are dealt with. The nature of the sun, the solar radiation spectrum, the estimation of total, direct, and diffuse radiation, and the heat transfer fundamentals for solar energy application are explained. The fundamentals, fabrication, and uses of various water and air heaters are outlined. Optics and concentrating collectors are dealt with, as well as solar furnaces. The various applications of solar energy are discussed, namely, solar pond, solar distillation, photovoltaic conversion of solar energy, solar refrigeration, solar hydrogen production, space applications, and solar measuring equipment. The cost of solar appliances is discussed. (MHR)

  20. Design of pilot-scale solar photocatalytic reactor for the generation of hydrogen from alkaline sulfide wastewater of sewage treatment plant.

    Science.gov (United States)

    Priya, R; Kanmani, S

    2013-01-01

    Experiments were conducted for photocatalytic generation of renewable fuel hydrogen from sulphide wastewater from the sewage treatment plant. In this study, pilot-scale solar photocatalytic reactor was designed for treating 1 m3 of sulphide wastewater and also for the simultaneous generation of hydrogen. Bench-scale studies were conducted both in the batch recycle and continuous modes under solar irradiation at similar experimental conditions. The maximum of 89.7% conversion was achieved in the continuous mode. The length of the pilot-scale solar photocatalytic reactor was arrived using the design parameters such as volumetric flow rate (Q) (11 x 10(-2) m3/s), inlet concentration of sulphide ion (C(in)) (28 mol/m3), conversion (89.7%) and average mass flow destruction rate (3.488 x 10(-6) mol/m2 s). The treatment cost of the process was estimated to be 6 US$/m3. This process would be suitable for India like sub-tropical country where sunlight is abundantly available throughout the year.

  1. The effect of surface hydrogenation of metal oxides on the nanomorphology and the charge generation efficiency of polymer blend solar cells

    Science.gov (United States)

    Vasilopoulou, Maria

    2014-10-01

    In this work, the effect of surface hydrogenation of different metal oxides, in particular molybdenum and tungsten oxides widely used to enhance hole extraction and zinc and titanium oxides widely used to enhance electron extraction, on the nanomorphology and the charge generation efficiency of polymer blend solar cells is investigated. It was found that photoactive layers based on blends using different polymers, in particular poly(3-hexythiophene) (P3HT) and poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT), which normally differ in both morphology and electronic structure, benefited, for both polymers, from deposition on metal oxides with high surface hydrogen content, in the sense that they exhibited improved crystallinity/order as revealed from X-ray diffraction, UV-vis absorption and elipsometric measurements. As a result, increased charge generation efficiencies and reduced recombination losses were measured in solar cells using metal oxides with highly hydrogenated surfaces at bottom electrodes and based on blends of either P3HT or PCDTBT, with a fullerene acceptor, as was verified by transient photocurrent measurements. The power conversion efficiency (PCE) of those cells reached values of 4.5% and 7.2%, respectively, an increase of about 30% compared with the cells using metal oxides with low surface hydrogen content.In this work, the effect of surface hydrogenation of different metal oxides, in particular molybdenum and tungsten oxides widely used to enhance hole extraction and zinc and titanium oxides widely used to enhance electron extraction, on the nanomorphology and the charge generation efficiency of polymer blend solar cells is investigated. It was found that photoactive layers based on blends using different polymers, in particular poly(3-hexythiophene) (P3HT) and poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2

  2. Surface passivation of c-Si for silicon heterojunction solar cells using high-pressure hydrogen diluted plasmas

    Directory of Open Access Journals (Sweden)

    Dimitrios Deligiannis

    2015-09-01

    Full Text Available In this work we demonstrate excellent c-Si surface passivation by depositing a-Si:H in the high-pressure and high hydrogen dilution regime. By using high hydrogen dilution of the precursor gases during deposition the hydrogen content of the layers is sufficiently increased, while the void fraction is reduced, resulting in dense material. Results show a strong dependence of the lifetime on the substrate temperature and a weaker dependence on the hydrogen dilution. After applying a post-deposition annealing step on the samples equilibration of the lifetime occurs independent of the initial nanostructure.

  3. Diabetic autonomic neuropathy.

    Science.gov (United States)

    Freeman, Roy

    2014-01-01

    Diabetes mellitus is the commonest cause of an autonomic neuropathy in the developed world. Diabetic autonomic neuropathy causes a constellation of symptoms and signs affecting cardiovascular, urogenital, gastrointestinal, pupillomotor, thermoregulatory, and sudomotor systems. Several discrete syndromes associated with diabetes cause autonomic dysfunction. The most prevalent of these are: generalized diabetic autonomic neuropathy, autonomic neuropathy associated with the prediabetic state, treatment-induced painful and autonomic neuropathy, and transient hypoglycemia-associated autonomic neuropathy. These autonomic manifestations of diabetes are responsible for the most troublesome and disabling features of diabetic peripheral neuropathy and result in a significant proportion of the mortality and morbidity associated with the disease.

  4. Concentrations of carbonyl sulfide and hydrogen cyanide in the free upper troposphere and lower stratosphere deduced from ATMOS/Spacelab 3 infrared solar occultation spectra

    Science.gov (United States)

    Zander, R.; Rinsland, C. P.; Russell, J. M., III; Farmer, C. B.; Norton, R. H.

    1988-01-01

    This paper presents the results on the volume mixing ratio profiles of carbonyl sulfide and hydrogen cyanide, deduced from the spectroscopic analysis of IR solar absorption spectra obtained in the occultation mode with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during its mission aboard Spacelab 3. A comparison of the ATMOS measurements for both northern and southern latitudes with previous field investigations at low midlatitudes shows a relatively good agreement. Southern Hemisphere volume mixing ratio profiles for both molecules were obtained for the first time, as were the profiles for the Northern Hemisphere covering the upper troposphere and the lower stratosphere simultaneously.

  5. Correlation between SiH2/SiH and light-induced degradation of p-i-n hydrogenated amorphous silicon solar cells

    Science.gov (United States)

    Keya, Kimitaka; Kojima, Takashi; Torigoe, Yoshihiro; Toko, Susumu; Yamashita, Daisuke; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2016-07-01

    We have measured the hydrogen content ratio I SiH2/I SiH associated with Si-H2 and Si-H bonds in p-i-n (PIN) a-Si:H solar cells by Raman spectroscopy. With decreasing I SiH2/I SiH, the efficiency, short-circuit current density, open-circuit voltage, and fill factor of PIN a-Si:H solar cells after light soaking tend to increase. Namely, I SiH2/I SiH correlates well with light-induced degradation of the cells. While a single I-layer has a low I SiH2/I SiH of 0.03-0.09, a PIN cell has I SiH2/I SiH = 0.18 because many Si-H2 bonds exist in the P-layer and at the P/I interface of the PIN solar cells. To realize PIN solar cells with higher stability, we must suppress Si-H2 bond formation in the P-layer and at the P/I interface.

  6. Hydrogenated amorphous silicon oxide (a-SiOx:H) single junction solar cell with 8.8% initial efficiency by reducing parasitic absorptions

    Science.gov (United States)

    Kim, Do Yun; Guijt, Erwin; van Swaaij, René A. C. M. M.; Zeman, Miro

    2017-04-01

    Hydrogenated amorphous silicon oxide (a-SiOx:H) solar cells have been successfully implemented to multi-junction thin film silicon solar cells. The efficiency of these solar cells, however, has still been below that of state-of-the-art solar cells mainly due to the low Jsc of the a-SiOx:H solar cells and the unbalanced current matching between sub-cells. In this study, we carry out optical simulations to find the main optical losses for the a-SiOx:H solar cell, which so far was mainly optimized for Voc and fill-factor (FF). It is observed that a large portion of the incident light is absorbed parasitically by the p-a-SiOx:H and n-a-SiOx:H layers, although the use of these layers leads to the highest Voc × FF product. When a more transparent and conductive p-nc-SiOx:H layer is substituted for the p-a-SiOx:H layer, the parasitic absorption loss at short wavelengths is notably reduced, leading to higher Jsc. However, this gain in Jsc by the use of the p-nc-SiOx:H compromises the Voc. When replacing the n-a-SiOx:H layer for an n-nc-SiOx:H layer that has low n and k values, the plasmonic absorption loss at the n-nc-SiOx:H/Ag interfaces and the parasitic absorption in the n-nc-SiOx:H are substantially reduced. Implementation of this n-nc-SiOx:H leads to an increase of the Jsc without a drop of the Voc and FF. When implementing a thinner p-a-SiOx:H layer, a thicker i-a-SiOx:H layer, and an n-nc-SiOx:H layer, a-SiOx:H solar cells with not only high Jsc but also high Voc and FF can be fabricated. As a result, an 8.8% a-SiOx:H single junction solar cell is successfully fabricated with a Voc of 1.02 V, a FF of 0.70, and a Jsc of 12.3 mA/cm2, which is the highest efficiency ever reported for this type of solar cell.

  7. CuFe2 O4 -CuO Nanocomposites as Promising Materials for Solar Hydrogen Generation

    Science.gov (United States)

    Razavi, Mehdi; Amrollahi, Pouya; Yazdimamaghani, Mostafa; Tayebi, Lobat; Vashaee, Daryoosh

    2014-03-01

    Currently, hydrogen is produced, almost exclusively, by waterelectrolysis. This method can take advantage of economies of scale and most established techniques of producing hydrogen. We developed a nanocomposite material system composed of CuFe2O4 and CuO semiconductor particles to produce hydrogen by electrolysis of water. The nanocomposite powder was prepared using the sol-gel method. Techniques of X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy and UV diffuse reflectance analysis were employed to characterize the synthesized products.The results confirmed the formation of CuFe2O4-CuO nanocomposite powder. The hydrogen evolution was successfully observed over the new hetero-system of CuFe2O4-CuO. The electrolysis activity depended on the concentration of CuO in the system. In order to enhance the hydrogen production, we further optimized the composite material versus the concentration of the compounds.

  8. Solar hydrogen generation by a CdS-Au-TiO2 sandwich nanorod array enhanced with Au nanoparticle as electron relay and plasmonic photosensitizer.

    Science.gov (United States)

    Li, Jiangtian; Cushing, Scott K; Zheng, Peng; Senty, Tess; Meng, Fanke; Bristow, Alan D; Manivannan, Ayyakkannu; Wu, Nianqiang

    2014-06-11

    This paper presents a sandwich-structured CdS-Au-TiO2 nanorod array as the photoanode in a photoelectrochemical cell (PEC) for hydrogen generation via splitting water. The gold nanoparticles sandwiched between the TiO2 nanorod and the CdS quantum dot (QD) layer play a dual role in enhancing the solar-to-chemical energy conversion efficiency. First, the Au nanoparticles serve as an electron relay, which facilitates the charge transfer between CdS and TiO2 when the CdS QDs are photoexcited by wavelengths shorter than 525 nm. Second, the Au nanoparticles act as a plasmonic photosensitizer, which enables the solar-to-hydrogen conversion at wavelengths longer than the band edge of CdS, extending the photoconversion wavelength from 525 to 725 nm. The dual role of Au leads to a photocurrent of 4.07 mA/cm(2) at 0 V (vs Ag|AgCl) under full solar spectrum irradiation and a maximum solar-to-chemical energy conversion efficiency of 2.8%. An inversion analysis is applied to the transient absorption spectroscopy data, tracking the transfer of electrons and holes in the heterostructure, relating the relaxation dynamics to the underlying coupled rate equation and revealing that trap-state Auger recombination is a dominant factor in interfacial charge transfer. It is found that addition of Au nanoparticles increases the charge-transfer lifetime, reduces the trap-state Auger rate, suppresses the long-time scale back transfer, and partially compensates the negative effects of the surface trap states. Finally, the plasmonic energy-transfer mechanism is identified as direct transfer of the plasmonic hot carriers, and the interfacial Schottky barrier height is shown to modulate the plasmonic hot electron transfer and back transfer. Transient absorption characterization of the charge transfer shows defect states cannot be ignored when designing QD-sensitized solar cells. This facile sandwich structure combines both the electrical and the optical functions of Au nanoparticles into a

  9. A-site substitution effect of perovskite-type cobalt and manganese oxides on two-step water splitting reaction for solar hydrogen production

    Science.gov (United States)

    Kaneko, Hiroshi; Hasegawa, Takumi; Mori, Kohei

    2017-06-01

    The perovskite type metal oxides (ABO3: A and B are metal elements) are attractive material for the two-step water splitting process to produce solar hydrogen, because the diversity of perovskite compound with substitution of metal ion makes its reducibility changeable. The perovskite-type cobalt and manganese oxides are prepared with substitution of metal ion in the A-site, and the performance of two-step water splitting reaction is investigated. The LaCoO3 and Ca0.45Sr0.4La0.15MnO3-δ, containing more trivalent metal ions in the A-site of perovskite structure, are most promising materials for solar hydrogen production. It is found that the two-step water-splitting reaction with Ca0.45Sr0.4La0.15MnO3-δ of the perovskite-type manganese oxide proceed stoichiometrically and Ca0.45Sr0.4La0.15MnO3-δ can produce much H2 gas (4cm3/g-sample) at the reduction temperature of 1400 °C.

  10. Improved efficiency of a large-area Cu(In,Ga)Se₂ solar cell by a nontoxic hydrogen-assisted solid Se vapor selenization process.

    Science.gov (United States)

    Wu, Tsung-Ta; Hu, Fan; Huang, Jyun-Hong; Chang, Chia-ho; Lai, Chih-chung; Yen, Yu-Ting; Huang, Hou-Ying; Hong, Hwen-Fen; Wang, Zhiming M; Shen, Chang-Hong; Shieh, Jia-Min; Chueh, Yu-Lun

    2014-04-01

    A nontoxic hydrogen-assisted solid Se vapor selenization process (HASVS) technique to achieve a large-area (40 × 30 cm(2)) Cu(In,Ga)Se2 (CIGS) solar panel with enhanced efficiencies from 7.1 to 10.8% (12.0% for active area) was demonstrated. The remarkable improvement of efficiency and fill factor comes from improved open circuit voltage (Voc) and reduced dark current due to (1) decreased interface recombination raised from the formation of a widened buried homojunction with n-type Cd(Cu) participation and (2) enhanced separation of electron and hole carriers resulting from the accumulation of Na atoms on the surface of the CIGS film. The effects of microstructural, compositional, and electrical characteristics with hydrogen-assisted Se vapor selenization, including interdiffusion of atoms and formation of buried homojunction, were examined in detail. This methodology can be also applied to CIS (CuInSe2) thin film solar cells with enhanced efficiencies from 5.3% to 8.5% (9.4% for active area) and provides a facile approach to improve quality of CIGS and stimulate the nontoxic progress in the large scale CIGS PV industry.

  11. Well-to-wheel analysis of renewable transport fuels: synthetic natural gas from wood gasification and hydrogen from concentrated solar energy[Dissertation 17437

    Energy Technology Data Exchange (ETDEWEB)

    Felder, R.

    2007-07-01

    In order to deal with problems such as climate change, an increasing energy demand and the finiteness of fossil resources, alternative CO{sub 2}-low technologies have to be found for a sustainable growing future. Laboratories at PSI are conducting research on two pathways delivering such car fuels: synthetic natural gas from wood gasification (SNG) and hydrogen from solar thermochemical ZnO dissociation (STD). The biofuel SNG is produced using wood in an auto-thermal gasification reactor. It can be supplied to the natural-gas grid and be used in a compressed natural gas (CNG) vehicle. STD is a long-term option, using concentrated solar radiation in a thermochemical reactor, producing zinc as solar energy carrier. Zinc can be used for hydrolysis, in order to produce hydrogen as a locally low-polluting future car fuel. In the frame of the thesis, both fuels are assessed using a life cycle assessment, i.e. investigating all environmental interactions from the extraction of resources over the processing and usage steps to the final disposal. Different methodologies are applied for a rating, compared to alternatives and standard fuels of today. In addition, costs of the technologies are calculated in order to assess economic competitiveness. The thesis is structured as follows: After an introduction giving an overview (chapter A), the methodology is presented (chapter B). It includes various life cycle impact assessment methods such as greenhouse gas emissions, the cumulative energy demand or comprehensive rating approaches. Calculations of the production and supply costs of the assessed fuels are included as well as the eco-efficiency, a combination of environmental with economic indicators. In addition, external costs caused by the emissions are quantified. Sensitivity studies investigate the importance of different parameters and substantiate conclusions. In chapter C, the production, supply and use of the assessed fuels is discussed, following the well

  12. Quantitative Autonomic Testing

    OpenAIRE

    Novak, Peter

    2011-01-01

    Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory shoul...

  13. Amorphous silicon films with high deposition rate prepared using argon and hydrogen diluted silane for stable solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, Purabi; Agarwal, Pratima [Department of Physics, IIT Guwahati, Guwahati 781039 (India); Dixit, P.N. [Plasma Processed Materials Division, National Physical Laboratory, New Delhi 110012 (India)

    2007-08-15

    Hydrogenated amorphous silicon films with high deposition rate (4-5 Aa/s) and reduced Staebler-Wronski effect are prepared using a mixture of silane (SiH{sub 4}), hydrogen and argon. The films show an improvement in short and medium range order. The structural, transport and stability studies on the films are done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman scattering studies, electrical conductivity and diffusion length measurement. Presence of both atomic hydrogen and Ar{sup *} in the plasma causes breaking of weak Si-Si bonds and subsequent reconstruction of strong bonds resulting in improvement of short and medium range order. The improved structural order enhances the stability of these films against light soaking. High deposition rate is due to the lesser etching of growing surface compared to the case of only hydrogen diluted silane. (author)

  14. 太阳能光解水制氢催化剂研究进展%Hydrogen Production from Water Decomposition with Solar Enegry

    Institute of Scientific and Technical Information of China (English)

    张建斌; 查飞; 左国防; 唐慧安

    2011-01-01

    Hydrogen production from water decomposition on photocatalysts with solar energy is an efficient way to transform solar energy to hydrogen energy.Photocatalysts developed in recent years for water decomposition are metal complexes,metal oxide,inorganicla layered compounds,Z-type photocatalytic hydrogen production reaction system,photocatalytic biological reaction system.The following method can improve photocatalytic activities effectively: metal loading,ion doping,composite semiconductor,dye sensitization,electron trapers,surface chelation and derivatives and external field coupling.To discovery new photocatalysts with peculiar construction and without precious metal loading and to recycle sacrificial agent will be the future direction of development.%利用太阳能制氢是将太阳能转换成氢能的有效方式。近年来国内外发展了不同类型的太阳能光解水制氢催化剂:金属配合物、金属氧化物、无机层状化合物、Z型光催化制氢反应体系和光生物催化反应体系等,通过金属负载、离子掺杂、复合半导体、燃料光敏化、电子捕获剂、表面螯合及衍生作用、外场耦合等途径可以有效提高光催化剂活性,开发具有特殊结构的新型光催化剂、无贵金属负载催化剂以及循环使用牺牲剂将是未来太阳能光解水制氢的发展方向。

  15. Hydrogen passivation of N(+)-P and P(+)-N heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, Basab; Davis, William C.; Ringel, Steve A.; Hoffman, Richard, Jr.

    1996-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n-p and p-n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)-p and p(+)-n heteroepitaxial InP cell structures from as-grown values of 5-7 x 10(exp 14) cm(exp -3), down to 3-5 x 10(exp 12) cm(exp -3). All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. One to five analysis indicated a subsequent approximately 100 fold decrease in reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)-n structures. In addition to being passivated, dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  16. Hydrogen Passivation of N(+)P and P(+)N Heteroepitaxial InP Solar Cell Structures

    Science.gov (United States)

    Chatterjee, B.; Davis, W. C.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n(+)p and p(+)n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)p and p(+)n heteroepitaxial InP cell structures from as-grown values of 5 - 7 x 10(exp 14)/cc, down to 3 - 5 x 10(exp 12)/cc. All dopants were successfully reactivated by a 400 C, 5 minute anneal With no detectable activation of deep levels. I-V analysis indicated a subsequent approx. 100 fold decrease In reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)n structures. ln addition to being passivated,dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  17. Autonomous Systems, Robotics, and Computing Systems Capability Roadmap: NRC Dialogue

    Science.gov (United States)

    Zornetzer, Steve; Gage, Douglas

    2005-01-01

    Contents include the following: Introduction. Process, Mission Drivers, Deliverables, and Interfaces. Autonomy. Crew-Centered and Remote Operations. Integrated Systems Health Management. Autonomous Vehicle Control. Autonomous Process Control. Robotics. Robotics for Solar System Exploration. Robotics for Lunar and Planetary Habitation. Robotics for In-Space Operations. Computing Systems. Conclusion.

  18. In-situ preparation of N-TiO2/graphene nanocomposite and its enhanced photocatalytic hydrogen production by H2S splitting under solar light

    Science.gov (United States)

    Bhirud, Ashwini P.; Sathaye, Shivaram D.; Waichal, Rupali P.; Ambekar, Jalindar D.; Park, Chan-J.; Kale, Bharat B.

    2015-03-01

    Highly monodispersed nitrogen doped TiO2 nanoparticles were successfully deposited on graphene (N-TiO2/Gr) by a facile in-situ wet chemical method for the first time. N-TiO2/Gr has been further used for photocatalytic hydrogen production using a naturally occurring abundant source of energy i.e. solar light. The N-TiO2/Gr nanocomposite composition was optimized by varying the concentrations of dopant nitrogen and graphene (using various concentrations of graphene) for utmost hydrogen production. The structural, optical and morphological aspects of nanocomposites were studied using XRD, UV-DRS, Raman, XPS, FESEM, and TEM. The structural study of the nanocomposite shows existence of anatase N-TiO2. Further, the details of the components present in the composition were confirmed with Raman and XPS. The morphological study shows that very tiny, 7-10 nm sized, N-TiO2 nanoparticles are deposited on the graphene sheet. The optical study reveals a drastic change in absorption edge and consequent total absorption due to nitrogen doping and presence of graphene. Considering the extended absorption edge to the visible region, these nanocomposites were further used as a photocatalyst to transform hazardous H2S waste into eco-friendly hydrogen using solar light. The N-TiO2/Gr nanocomposite with 2% graphene exhibits enhanced photocatalytic stable hydrogen production i.e. ~5941 μmol h-1 under solar light irradiation using just 0.2 gm nanocomposite, which is much higher as compared to P25, undoped TiO2 and TiO2/Gr nanocomposite. The enhancement in the photocatalytic activity is attributed to `N' doping as well as high specific surface area and charge carrier ability of graphene. The recycling of the photocatalyst shows a good stability of the nanocomposites. This work may provide new insights to design other semiconductor deposited graphene novel nanocomposites as a visible light active photocatalyst.Highly monodispersed nitrogen doped TiO2 nanoparticles were successfully

  19. Constraining Aggregate-Scale Solar Energy Partitioning in Arctic Sea Ice Through Synthesis of Remote Sensing and Autonomous In-Situ Observations.

    Science.gov (United States)

    Wright, N.; Polashenski, C. M.; Deeb, E. J.; Morriss, B. F.; Song, A.; Chen, J.

    2015-12-01

    One of the key processes controlling sea ice mass balance in the Arctic is the partitioning of solar energy between reflection back to the atmosphere and absorption into the ice and upper ocean. We investigate the solar energy balance in the ice-ocean system using in-situ data collected from Arctic Observing Network (AON) sea ice sites and imagery from high resolution optical satellites. AON assets, including ice mass balance buoys and ice tethered profilers, monitor the storage and fluxes of heat in the ice-ocean system. High resolution satellite imagery, processed using object-based image classification techniques, allows us to quantify the evolution of surrounding ice conditions, including melt pond coverage and floe size distribution, at aggregate scale. We present results from regionally representative sites that constrain the partitioning of absorbed solar energy between ice melt and ocean storage, and quantify the strength of the ice-albedo feedback. We further demonstrate how the results can be used to validate model representations of the physical processes controlling ice-albedo feedbacks. The techniques can be extended to understand solar partitioning across the Arctic basin using additional sites and model based data integration.

  20. Multi-resonant silver nano-disk patterned thin film hydrogenated amorphous silicon solar cells for Staebler-Wronski effect compensation

    CERN Document Server

    Vora, Ankit; Pearce, Joshua M; Bergstrom, Paul L; Güney, Durdu Ö

    2014-01-01

    We study polarization independent improved light trapping in commercial thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic cells using a three-dimensional silver array of multi-resonant nano-disk structures embedded in a silicon nitride anti-reflection coating (ARC) to enhance optical absorption in the intrinsic layer (i-a-Si:H) for the visible spectrum for any polarization angle. Predicted total optical enhancement (OE) in absorption in the i-a-Si:H for AM-1.5 solar spectrum is 18.51% as compared to the reference, and producing a 19.65% improvement in short-circuit current density (JSC) over 11.7 mA/cm2 for a reference cell. The JSC in the nano-disk patterned solar cell (NDPSC) was found to be higher than the commercial reference structure for any incident angle. The NDPSC has a multi-resonant optical response for the visible spectrum and the associated mechanism for OE in i-a-Si:H layer is excitation of Fabry-Perot resonance facilitated by surface plasmon resonances. The detrimental Staebl...

  1. Photoelectrochemical hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Rocheleau, R.; Misra, A.; Miller, E. [Univ. of Hawaii, Honolulu, HI (United States)

    1998-08-01

    A significant component of the US DOE Hydrogen Program is the development of a practical technology for the direct production of hydrogen using a renewable source of energy. High efficiency photoelectrochemical systems to produce hydrogen directly from water using sunlight as the energy source represent one of the technologies identified by DOE to meet this mission. Reactor modeling and experiments conducted at UH provide strong evidence that direct solar-to-hydrogen conversion efficiency greater than 10% can be expected using photoelectrodes fabricated from low-cost, multijunction (MJ) amorphous silicon solar cells. Solar-to-hydrogen conversion efficiencies as high as 7.8% have been achieved using a 10.3% efficient MJ amorphous silicon solar cell. Higher efficiency can be expected with the use of higher efficiency solar cells, further improvement of the thin film oxidation and reduction catalysts, and optimization of the solar cell for hydrogen production rather than electricity production. Hydrogen and oxygen catalysts developed under this project are very stable, exhibiting no measurable degradation in KOH after over 13,000 hours of operation. Additional research is needed to fully optimize the transparent, conducting coatings which will be needed for large area integrated arrays. To date, the best protection has been afforded by wide bandgap amorphous silicon carbide films.

  2. High-temperature hydrogenation of pure and silver-decorated titanate nanotubes to increase their solar absorbance for photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Plodinec, Milivoj [Ruđer Bošković Institute, Bijenička 54, HR-1002 Zagreb (Croatia); Gajović, Andreja, E-mail: gajovic@irb.hr [Ruđer Bošković Institute, Bijenička 54, HR-1002 Zagreb (Croatia); Jakša, Gregor; Žagar, Kristina; Čeh, Miran [Institute Jožef Stefan, Jamova 39, 1000 Ljubljana (Slovenia)

    2014-04-05

    Graphical abstract: The aim of the work is to study how annealing in a reducing atmosphere of titanate nanotubes (TiNT) and Ag decorated titanate nanotubes (TiNT@Ag) influenced on their structure, morphology, phase transitions, UV–ViS-NIR absorbance and photocatalytic activity. An increase of photocatalytic activity after a heat treatment in a reducing atmosphere was observed in the TiNT and TiNT@Ag. We found that the hydrogenated TiNT@Ag samples (TiNT@Ag-HA) had a two-times higher photodegradation impact on the caffeine than the TiNT samples, which is a consequence of the increased absorption of visible light and the synergetic effects between the silver and the TiO{sub 2} nanoparticles that increase the efficiency of the formation of electron–hole pairs and the charge transfer to the surface of the nanoparticles. -- Highlights: • Titanate nanotubes with and without Ag nanoparticles were hydrogenated at 550 °C. • TiO{sub 2} nanostructures obtained by hydrogenation have core–shell structure. • Hydrogenated samples show absorption in the visible spectral region. • Hydrogenated Ag decorated sample show stronger absorption in visible than in UV. • Photocatalytic efficiency is improved by hydrogenation and by Ag nanoparticles. -- Abstract: Titanate nanotubes (TiNTs) and silver-decorated titanate nanotubes (TiNTs@Ag) were synthesized using the hydrothermal method. In the decorated nanotubes the silver particles were obtained by the photoreduction of AgNO{sub 3} under UV light. Pure and Ag-decorated nanotubes were high-temperature heat treated at 550 °C in a hydrogen atmosphere and the “core–shell”-structured TiO{sub 2} nanoparticles were formed. For the structural characterization of all the titanate nanostructures we used conventional and analytical transmission electron microscopy (TEM) techniques, X-ray diffraction (XRD) and Raman spectroscopy. The Ag-decorated titanate nanostructures were additionally studied by X-ray photo

  3. Modeling, Control, and Simulation of a Solar Hydrogen/Fuel Cell Hybrid Energy System for Grid-Connected Applications

    Directory of Open Access Journals (Sweden)

    Tourkia Lajnef

    2013-01-01

    Full Text Available Different energy sources and converters need to be integrated with each other for extended usage of alternative energy, in order to meet sustained load demands during various weather conditions. The objective of this paper is to associate photovoltaic generators, fuel cells, and electrolysers. Here, to sustain the power demand and solve the energy storage problem, electrical energy can be stored in the form of hydrogen. By using an electrolyser, hydrogen can be generated and stored for future use. The hydrogen produced by the electrolyser using PV power is used in the FC system and acts as an energy buffer. Thus, the effects of reduction and even the absence of the available power from the PV system can be easily tackled. Modeling and simulations are performed using MATLAB/Simulink and SimPowerSystems packages and results are presented to verify the effectiveness of the proposed system.

  4. Autoimmune autonomic disorders.

    Science.gov (United States)

    Mckeon, Andrew; Benarroch, Eduardo E

    2016-01-01

    Autoimmune autonomic disorders occur because of an immune response directed against sympathetic, parasympathetic, and enteric ganglia, autonomic nerves, or central autonomic pathways. In general, peripheral autoimmune disorders manifest with either generalized or restricted autonomic failure, whereas central autoimmune disorders manifest primarily with autonomic hyperactivity. Some autonomic disorders are generalized, and others are limited in their anatomic extent, e.g., isolated gastrointestinal dysmotility. Historically, these disorders were poorly recognized, and thought to be neurodegenerative. Over the last 20 years a number of autoantibody biomarkers have been discovered that have enabled the identification of certain patients as having an autoimmune basis for either autonomic failure or hyperactivity. Peripheral autoimmune autonomic disorders include autoimmune autonomic ganglionopathy (AAG), paraneoplastic autonomic neuropathy, and acute autonomic and sensory neuropathy. AAG manifests with acute or subacute onset of generalized or selective autonomic failure. Antibody targeting the α3 subunit of the ganglionic-type nicotinic acetylcholine receptor (α3gAChR) is detected in approximately 50% of cases of AAG. Some other disorders are characterized immunologically by paraneoplastic antibodies with a high positive predictive value for cancer, such as antineuronal nuclear antibody, type 1 (ANNA-1: anti-Hu); others still are seronegative. Recognition of an autoimmune basis for autonomic disorders is important, as their manifestations are disabling, may reflect an underlying neoplasm, and have the potential to improve with a combination of symptomatic and immune therapies.

  5. Optimization of n/i and i/p buffer layers in n-i-p hydrogenated microcrystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    Yuan Yujie; Hou Guofu; Zhang Jianjun; Xue Junming; Cao Liran; Zhao Ying; Geng Xinhua

    2009-01-01

    Hydrogenated microcrystalline silicon (μc-Si:H) intrinsic films and solar cells with n-i-p configuration were prepared by plasma enhanced chemical vapor deposition (PECVD). The influence of n/i and i/p buffer layerson the μc-Si:H cell performance was studied in detail. The experimental results demonstrated that the efficiency is much improved when there is a higher crystallinity at n/i interface and an optimized a-Si:H buffer layer at i/p interface. By combining the above methods, the performance ofμc-Si:H single-junction and a-Si:H/μc-Si:H tandemsolar ceils has been significantly improved.

  6. Autonomic Nervous System Disorders

    Science.gov (United States)

    Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart ... breathing and swallowing Erectile dysfunction in men Autonomic nervous system disorders can occur alone or as the result ...

  7. Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Yen-Tang Huang

    2014-01-01

    Full Text Available Hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H alloys were developed for application in Si-based thin-film solar cells. The effects of the germane concentration (RGeH4 and the hydrogen ratio (RH2 on the μc-Si1-xGex:H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a-Si1-xGex:H and μc-Si1-xGex:H were also compared. Similar to a-Si1-xGex:H, the preferential Ge incorporation was observed in μc-Si1-xGex:H. Moreover, a higher RH2 significantly promoted Ge incorporation for a-Si1-xGex:H, while the Ge content was not affected by RH2 in μc-Si1-xGex:H growth. Furthermore, to eliminate the crystallization effect, the 0.9 μm thick absorbers with a similar crystalline volume fraction were applied. With the increasing RGeH4, the accompanied increase in Ge content of μc-Si1-xGex:H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization of RH2 and RGeH4, the single-junction μc-Si1-xGex:H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared to μc-Si:H cell, the external quantum efficiency at 800 nm had a relative increase by 33.1%.

  8. Enhanced photocatalytic hydrogen evolution activity of CuInS{sub 2} loaded TiO{sub 2} under solar light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changjiang [Department of Chemistry, Huangshan University, Huangshan 245041 (China); Xi, Zhenhao; Fang, Wenzhang; Xing, Mingyang [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Zhang, Jinlong, E-mail: jlzhang@ecust.edu.cn [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Department of Chemistry, Tsinghua University, Beijing 100084 (China)

    2015-03-15

    In this paper, p–n type CuInS{sub 2}/TiO{sub 2} particles were prepared in ethylenediamine by the solvothermal method. The microstructural properties of the synthesized p–n type catalysts were characterized by X-ray diffraction (XRD) in order to confirm the existence of crystalline CuInS{sub 2} on the surface of TiO{sub 2}, which was also confirmed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) images provided the detailed morphological properties about the CuInS{sub 2}/TiO{sub 2} heterostructure. UV–vis diffuse reflectance spectroscopy (UV–vis DRS) was used to investigate the optical properties of the CuInS{sub 2}/TiO{sub 2} particles. The DRS results indicated that both the p–n type structure and CuInS{sub 2} acting as a sensitizer can enhance significantly the absorption of UV and visible light. The photocatalytic activities of the CuInS{sub 2}/TiO{sub 2} particles were evaluated by hydrogen evolution reactions using Xe-lamp irradiation as a simulated solar light source. The greatly enhanced photocatalytic activity of hydrogen evolution under simulated solar light is about ~7 fold higher than that of pure commercial TiO{sub 2} (Degussa P25). - Graphical abstract: The heterojunction structure of CuInS{sub 2}/TiO{sub 2} promoted the efficiency of photoinduced charge carrier transfer and highly inherited the recombination of activated electrons and holes. - Highlight: • CuInS{sub 2}/TiO{sub 2} was prepared by a one-step solvothermal method. • 2.5% CuInS{sub 2}/TiO{sub 2} has the highest activity and keeps the activity stable. • Heterojunction structure of sample promoted the separation of electrons and holes.

  9. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

    OpenAIRE

    Bao, Xiao-Qing; Cerqueira, M.F.; Alpuim, P.; Liu, Lifeng

    2015-01-01

    We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction. L. F. Liu acknowledges the financial support by the FCT Investigator grant (IF/01595/2014).

  10. Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution.

    Science.gov (United States)

    Bao, Xiao-Qing; Fatima Cerqueira, M; Alpuim, Pedro; Liu, Lifeng

    2015-07-01

    We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.

  11. [Trigeminal autonomic cephalgias].

    Science.gov (United States)

    Maximova, M Yu; Piradov, M A; Suanova, E T; Sineva, N A

    2015-01-01

    Review of literature on the trigeminal autonomic cephalgias are presented. Trigeminal autonomic cephalgias are primary headaches with phenotype consisting of trigeminal pain with autonomic sign including lacrimation, rhinorrhea and miosis. Discussed are issues of classification, pathogenesis, clinical picture, diagnosis, differential diagnosis and treatment of this headache. Special attention is paid to cluster headache, paroxysmal hemicrania, SUNCT syndrome, hemicrania continua.

  12. Copper(ii) tungstate nanoflake array films: sacrificial template synthesis, hydrogen treatment, and their application as photoanodes in solar water splitting

    Science.gov (United States)

    Hu, Dianyi; Diao, Peng; Xu, Di; Xia, Mengyang; Gu, Yue; Wu, Qingyong; Li, Chao; Yang, Shubin

    2016-03-01

    We report the preparation of CuWO4 nanoflake (NF) array films by using a solid phase reaction method in which WO3 NFs were employed as sacrificial templates. The SEM, TEM and XRD results demonstrated that the obtained CuWO4 films possessed a network structure that was composed of single crystalline NFs intersected with each other. The CuWO4 NF films showed superior photoelectrochemical (PEC) activity to other CuWO4 photoanodes reported recently for the oxygen evolution reaction (OER). We attributed the high activity to the unique morphological and crystalline structure of the CuWO4 film, which enhanced the photoactivity by providing a large specific area, a short hole transport distance from the inside of CuWO4 to the CuWO4/solution interface, and a low grain boundary density. Hydrogen treatment by annealing the CuWO4 NF film in mixed gases of H2 and Ar could further enhance the photoactivity, as hydrogen treatment significantly increased the electron density of CuWO4 by generating oxygen vacancy in the lattice. The photocurrent density for OER obtained on the hydrogen-treated (H-treated) CuWO4 NF film is the largest ever reported on CuWO4 photoanodes in the literature. Moreover, the CuWO4 photoanodes exhibit good stability in weak alkaline solution, while the H-treated CuWO4 photoanodes exhibit acceptable stability. This work not only reveals the potential of CuWO4 as a photoanode material for solar water splitting but also shows that the construction of nanostructured CuWO4 photoanodes is a promising method to achieve high PEC activity toward OER.We report the preparation of CuWO4 nanoflake (NF) array films by using a solid phase reaction method in which WO3 NFs were employed as sacrificial templates. The SEM, TEM and XRD results demonstrated that the obtained CuWO4 films possessed a network structure that was composed of single crystalline NFs intersected with each other. The CuWO4 NF films showed superior photoelectrochemical (PEC) activity to other CuWO4

  13. The microalga Chlamydomonas reinhardtii CW-15 as a solar cell for hydrogen peroxide photoproduction. Comparison between free and immobilized cells and thylakoids for energy conversion efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, W.; Galvan, F.; Rosa, F.F. de la [Instituto de Bioquimica Vegetal y Fotosintesis, Universidad de Sevilla y CSIC, Sevilla (Spain)

    1995-11-28

    Immobilized cells and thylakoid vesicles of the microalga Chlamydomonas reinhardtii CW-15 have been developed as a solar cell because of their capabilities of producing hydrogen peroxide. This compound is an efficient and clean fuel used for rocket propulsion, motors and for heating. Hydrogen peroxide is produced by the photosystem in a catalyst cycle in which a redox mediator (methyl viologen) is reduced by electrons obtained from water by the photosynthetic apparatus of the microalga and it is re-oxidized by the oxygen dissolved in the solution. The photoproduction has been investigated using a discontinuous system with whole cells, or thylakoid vesicles, free or immobilized on alginate. The stimulation by azide as an inhibitor of catalase has also been analyzed. Under determined optimum conditions, the photoproduction by Ca-alginate entrapped cells, with a rate of 33 {mu}mol H{sub 2}O{sub 2}/mg Chl.h, was maintained for several hours with an energy conversion efficiency of 0.25%

  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.

  15. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere II. Continuous Emission and Condensed Matter Within the Corona

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The K-corona, a significant portion of the solar atmosphere, displays a continuous spectrum which closely parallels photospheric emission, though without the presence of overlying Fraunhofer lines. The E-corona exists in the same region and is characterized by weak emission lines from highly ionized atoms. For instance, the famous green emission line from coronium (FeXIV is part of the E-corona. The F-corona exists beyond the K/E-corona and, like the photospheric spectrum, is characterized by Fraunhofer lines. The F-corona represents photospheric light scattered by dust particles in the interplanetary medium. Within the gaseous models of the Sun, the K-corona is viewed as photospheric radiation which has been scattered by relativistic electrons. This scattering is thought to broaden the Fraunhofer lines of the solar spectrum such that they can no longer be detected in the K-corona. Thus, the gaseous models of the Sun account for the appearance of the K-corona by distorting photospheric light, since they are unable to have recourse to condensed matter to directly produce such radiation. Conversely, it is now advanced that the continuous emission of the K-corona and associated emission lines from the E-corona must be interpreted as manifestations of the same phenomenon: condensed matter exists in the corona. It is well-known that the Sun expels large amounts of material from its surface in the form of flares and coronal mass ejections. Given a liquid metallic hydrogen model of the Sun, it is logical to assume that such matter, which exists in the condensed state on the solar surface, continues to manifest its nature once expelled into the corona. Therefore, the continuous spectrum of the K-corona provides the twenty-seventh line of evidence that the Sun is composed of condensed matter.

  16. Effect of hydrogen doping on the properties of Al and F co-doped ZnO films for thin film silicon solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang-Hsing, E-mail: fansen@dragon.nchu.edu.tw; Yang, Tung-Hsin

    2016-04-30

    Aluminum and fluorine co-doped zinc oxide (AFZO) thin films were prepared in Ar + H{sub 2} atmospheres by rf magnetron sputtering at room temperature. The structural, electrical, and optical properties of the prepared films were investigated using X-ray diffraction, scanning electron microscopy, atomic force microscopy, Hall-effect measurement, X-ray photoelectron spectroscopy, and ultraviolet–visible spectrometry, and their dependence on deposition atmosphere (i.e. H{sub 2} / (H{sub 2} + Ar) ratio) was studied. The resulting films showed a (0 0 2) diffraction peak, indicating a typical wurtzite structure, and the optimal film crystallinity was obtained with the H{sub 2} / (H{sub 2} + Ar) ratio of 3%. The electrical resistivity of AFZO films decreased to 9.16 × 10{sup −4} Ω-cm, which was lower than ZnO:Al and ZnO:F films due to double doping effect of Al and F. The resistivity further decreased to below 5 × 10{sup −4} Ω-cm for the AFZO film with the H{sub 2} / (H{sub 2} + Ar) ratio of 3%–5%. All the films regardless of hydrogen content displayed high transmittances (> 92%) in the visible wavelength range. Applying the developed AFZO films as front transparent electrodes, amorphous Si thin film solar cells were fabricated and the open-circuit voltage, fill factor, and efficiency of the cell with the hydrogenated AFZO film were improved in contrast to those without the hydrogenated film. - Highlights: • H{sub 2} doping improves optoelectronic properties of Al, F co-doped ZnO (AFZO) films. • Resistivity of AFZO films decreases to 4.4 × 10{sup −4} Ω-cm with the 3% H{sub 2}/(Ar + H{sub 2}) ratio. • AFZO films show high average visible transmittances of above 92%. • Efficiency of a-Si thin film solar cells is improved by AFZO:H as front electrode.

  17. The autonomic laboratory

    Science.gov (United States)

    Low, P. A.; Opfer-Gehrking, T. L.

    1999-01-01

    The autonomic nervous system can now be studied quantitatively, noninvasively, and reproducibly in a clinical autonomic laboratory. The approach at the Mayo Clinic is to study the postganglionic sympathetic nerve fibers of peripheral nerve (using the quantitative sudomotor axon reflex test [QSART]), the parasympathetic nerves to the heart (cardiovagal tests), and the regulation of blood pressure by the baroreflexes (adrenergic tests). Patient preparation is extremely important, since the state of the patient influences the results of autonomic function tests. The autonomic technologist in this evolving field needs to have a solid core of knowledge of autonomic physiology and autonomic function tests, followed by training in the performance of these tests in a standardized fashion. The range and utilization of tests of autonomic function will likely continue to evolve.

  18. Development of a very fast spectral response measurement system for analysis of hydrogenated amorphous silicon solar cells and modules

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.A., E-mail: jose.rodriguez@tsolar.eu [Dept. Technology, Development and Innovation, T-Solar Global S.A., Parque Tecnologico de Galicia, Avda. de Vigo 5, E-32900 San Cibrao das Vinas (Ourense) (Spain); Fortes, M. [Departamento de Electronica e Computacion, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Alberte, C.; Vetter, M.; Andreu, J. [Dept. Technology, Development and Innovation, T-Solar Global S.A., Parque Tecnologico de Galicia, Avda. de Vigo 5, E-32900 San Cibrao das Vinas (Ourense) (Spain)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Spectral response equipment for measuring a-Si:H solar cells in a few seconds. Black-Right-Pointing-Pointer Equipment based on 16 LEDs with simultaneous illumination of the solar cell. Black-Right-Pointing-Pointer The current generated by each LED is analyzed by a Fast Fourier Transform. Black-Right-Pointing-Pointer Cheap equipment without lock-in technology for the current measurement. Black-Right-Pointing-Pointer Measurement error vs. conventional measurement less than 1% in J{sub sc}. - Abstract: An important requirement for a very fast spectral response measurement system is the simultaneous illumination of the solar cell at multiple well defined wavelengths. Nowadays this can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths. For the purpose to measure the spectral response (SR) of amorphous silicon solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 800 nm was performed. In the here developed equipment the LED illumination is modulated in the frequency range from 100 Hz to 200 Hz and the current generated by each LED is analyzed by a Fast Fourier Transform (FFT) to determine the current component corresponding to each wavelength. The equipment provides a signal to noise ratio of 2-4 orders of magnitude for individual wavelengths resulting in a precise measurement of the SR over the whole wavelength range. The difference of the short circuit current determined from the SR is less than 1% in comparison to a conventional system with monochromator.

  19. Near-uv photon efficiency in a TiO2 electrode - Application to hydrogen production from solar energy

    Science.gov (United States)

    Desplat, J.-L.

    1976-01-01

    An n-type (001) TiO2 electrode irradiated at 365 nm was tested under anodic polarization. A saturation current independent of pH and proportional to light intensity has been observed. Accurate measurements of the incident power lead to a 60 per cent photon efficiency. A photoelectrochemical cell built with such an electrode, operated under solar irradiation without concentration, produced an electrolysis current of 0.7 mA/sq cm without applied voltage.

  20. Hydrogen from renewable resources research

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, P.K.; McKinley, K.R.

    1990-07-01

    In 1986 the Hawaii Natural Energy Institute (HNEI) and the Florida Solar Energy Center (FSEC) were contracted by the Solar Energy Research Institute (SERI) to conduct an assessment of hydrogen production technologies and economic feasibilities of the production and use of hydrogen from renewable resources. In the 1989/90 period all monies were directed toward research and development with an emphasis on integration of tasks, focusing on two important issues, production and storage. The current year's efforts consisted of four tasks, one task containing three subtasks: Hydrogen Production by Gasification of Glucose and Wet Biomass in Supercritical Water; Photoelectrochemical Production of Hydrogen; Photoemission and Photoluminescence Studies of Catalyzed Photoelectrode Surfaces for Hydrogen Production; Solar Energy Chemical Conversion by Means of Photoelectrochemical (PEC) Methods Using Coated Silicon Electrodes; Assessment of Impedance Spectroscopy Methods for Evaluation of Semiconductor-Electrolyte Interfaces; Solar Energy Conversion with Cyanobacteria; Nonclassical Polyhydride Metal Complexes as Hydrogen Storage Materials. 61 refs., 22 figs., 11 tabs.

  1. Hydrogen from renewable resources research

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, P.K.; McKinley, K.R.

    1990-07-01

    In 1986 the Hawaii Natural Energy Institute (HNEI) and the Florida Solar Energy Center (FSEC) were contracted by the Solar Energy Research Institute (SERI) to conduct an assessment of hydrogen production technologies and economic feasibilities of the production and use of hydrogen from renewable resources. In the 1989/90 period all monies were directed toward research and development with an emphasis on integration of tasks, focusing on two important issues, production and storage. The current year's efforts consisted of four tasks, one task containing three subtasks: Hydrogen Production by Gasification of Glucose and Wet Biomass in Supercritical Water; Photoelectrochemical Production of Hydrogen; Photoemission and Photoluminescence Studies of Catalyzed Photoelectrode Surfaces for Hydrogen Production; Solar Energy Chemical Conversion by Means of Photoelectrochemical (PEC) Methods Using Coated Silicon Electrodes; Assessment of Impedance Spectroscopy Methods for Evaluation of Semiconductor-Electrolyte Interfaces; Solar Energy Conversion with Cyanobacteria; Nonclassical Polyhydride Metal Complexes as Hydrogen Storage Materials. 61 refs., 22 figs., 11 tabs.

  2. Influence of hydrogen sulfide annealing on copper-zinc-tin-sulfide solar cells sputtered from a quaternary compound target

    Energy Technology Data Exchange (ETDEWEB)

    Bras, Patrice, E-mail: patrice.bras@angstrom.uu.se [Midsummer AB, Elektronikhöjden 6, SE-17543 Järfälla (Sweden); Solid State Electronics, Uppsala University, Box 534, 75121 Uppsala (Sweden); Sterner, Jan, E-mail: jan.sterner@midsummer.se [Midsummer AB, Elektronikhöjden 6, SE-17543 Järfälla (Sweden); Platzer-Björkman, Charlotte, E-mail: charlotte.platzer@angstrom.uu.se [Solid State Electronics, Uppsala University, Box 534, 75121 Uppsala (Sweden)

    2015-05-01

    With a theoretical efficiency around 30% and an optimized band gap for sunlight absorption, Cu{sub 2}ZnSnS{sub 4} (CZTS) is a promising, earth-abundant, material for thin film solar cells. Sputtering CZTS from a quaternary compound target is a quick and potentially industrial-scaled process that has not been investigated deeply yet. Our approach is based on an in-line vacuum system for the complete device. CZTS is sputtered from a compound target on a sodium molybdate (MoNa) pre-sputtered stainless steel substrate, and then annealed in high-pressure H{sub 2}S atmosphere. A 1 μm thick absorber is obtained within 7 minute sputtering. Top layers are then deposited, without vacuum breaking. The effects of different annealing temperatures on the absorber morphology and composition are investigated. It is observed that recrystallization already occurs at 420 °C and that crystallinity improves with increasing temperature up to 550 °C. However, micro-sphere formation underneath the film degrades the corresponding solar cell performance dramatically above 510 °C. It is shown that sodium is needed in order to enhance recrystallization of CZTS but the MoNa layer thickness seems not to be a critical parameter. Scanning electron microscopy, X-ray diffraction, X-ray fluorescence and current-voltage measurement were used to characterize the samples. - Highlights: • CZTS sputtered from a quaternary compound target for solar cell fabrication • In-line vacuum tool for the complete device • Increasing crystallinity with sodium incorporation and annealing temperature up to 550 °C • Best device exhibits 4.2% efficiency.

  3. Determination of photo conversion efficiency of nanotubular titanium oxide photo-electrochemical cell for solar hydrogen generation

    Science.gov (United States)

    Raja, K. S.; Mahajan, V. K.; Misra, M.

    Anodized and annealed titanium oxide nanotubes show enhanced photo activity and can be used as photo anodes for water electrolysis in hydrogen generation. Application of an external potential to the photo anode is required for enhancement of the photocurrent. This additional electrical energy input complicates the photo conversion efficiency calculation. In this investigation, the photo-electrochemical behavior of anodized titanium oxide nanotubular arrays have been characterized in various electrolytes. Increase in the applied potential increased the photocurrent under illumination with visible light. A simple experimental method for calculating the photo conversion efficiency has been proposed. According to this method, the potential difference between the photo anode and cathode is measured with and without light illumination. The product of the photocurrent and the increase in potential due to light irradiation is considered as the net power output. The photocurrent and the conversion efficiency increased with increase in the pH of the electrolyte. TiO 2 nanotubular arrays annealed at 350 °C for 6 h in nitrogen atmosphere showed a maximum photo conversion efficiency of ∼4% in 1 M KOH electrolyte and ∼3% in 3.5 wt.% sodium chloride solution. The results indicate that nanotubular TiO 2 can be potentially used for the photo electrolysis of seawater to generate hydrogen.

  4. Plasmonic ZnO/Ag embedded structures as collecting layers for photogenerating electrons in solar hydrogen generation photoelectrodes.

    Science.gov (United States)

    Chen, Hao Ming; Chen, Chih Kai; Tseng, Ming Lun; Wu, Pin Chieh; Chang, Chia Min; Cheng, Liang-Chien; Huang, Hsin Wei; Chan, Ting Shan; Huang, Ding-Wei; Liu, Ru-Shi; Tsai, Din Ping

    2013-09-09

    A new fabrication strategy in which Ag plasmonics are embedded in the interface between ZnO nanorods and a conducting substrate is experimentally demonstrated using a femtosecond-laser (fs-laser)-induced plasmonic ZnO/Ag photoelectrodes. This fs-laser fabrication technique can be applied to generate patternable plasmonic nanostructures for improving their effectiveness in hydrogen generation. Plasmonic ZnO/Ag nanostructure photoelectrodes show an increase in the photocurrent of a ZnO nanorod photoelectrodes by higher than 85% at 0.5 V. Both localized surface plasmon resonance in metal nanoparticles and plasmon polaritons propagating at the metal/semiconductor interface are available for improving the capture of sunlight and collecting charge carriers. Furthermore, in-situ X-ray absorption spectroscopy is performed to monitor the plasmonic-generating electromagnetic field upon the interface between ZnO/Ag nanostructures. This can reveal induced vacancies on the conduction band of ZnO, which allow effective separation of charge carriers and improves the efficiency of hydrogen generation. Plasmon-induced effects enhance the photoresponse simultaneously, by improving optical absorbance and facilitating the separation of charge carriers.

  5. Effect of TCO/μc-Si:H Interface Modification on Hydrogenated Microcrystalline Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Shin-Wei Liang

    2013-01-01

    Full Text Available The effects of H2 plasma exposure on optical, electrical, and structural properties of fluorine-doped tin oxide (FTO and AZO/FTO substrates have been investigated. With increasing the time of H2-plasma exposure, the hydrogen radical and ions penetrated through the FTO surface to form more suboxides such as SnO and metallic Sn, which was confirmed by the XPS analysis. The Sn reduction on the FTO surface can be effectively eliminated by capping the FTO with a very thin layer of sputtered aluminum-doped zinc oxide (AZO, as confirmed by the XPS analysis. By using the AZO/FTO as front TCO with the subsequent annealing, the p-i-n μc-Si:H cell exhibited a significantly enhanced JSC from 15.97 to 19.40 mA/cm2 and an increased conversion efficiency from 5.69% to 7.09%. This significant enhancement was ascribed to the effective elimination of the Sn reduction on the FTO surface by the thin AZO layer during the Si-based thin-film deposition with hydrogen-rich plasma exposure. Moreover, the subsequent annealing of the sputtered AZO could lead to less defects as well as a better interface of AZO/FTO.

  6. Electrochemically deposited Cu2O cubic particles on boron doped diamond substrate as efficient photocathode for solar hydrogen generation

    Science.gov (United States)

    Mavrokefalos, Christos K.; Hasan, Maksudul; Rohan, James F.; Compton, Richard G.; Foord, John S.

    2017-06-01

    Herein, we report a novel photocathode for the water splitting reaction. The electrochemical deposition of Cu2O particles on boron doped diamond (BDD) electrodes and the subsequent decoration with NiO nanoparticles by a dip coating method to act as co-catalyst for hydrogen evolution reaction is described. The morphology analysis by scanning electron microscope (SEM) revealed that Cu2O particles are cubic and decorated sporadically with NiO nanoparticles. X-ray photoelectron spectroscopy (XPS) confirmed the electronic interaction at the interface between Cu2O and NiO through a binding energy shift of the main Cu 2p peak. The photoelectrochemical (PEC) performance of NiO-Cu2O/BDD showed a much higher current density (-0.33 mA/cm2) and photoconversion efficiency (0.28%) compared to the unmodified Cu2O/BDD electrode, which are only -0.12 mA/cm2 and 0.06%, respectively. The enhancement in PEC performance is attributable to the synergy of NiO as an electron conduction mediator leading to the enhanced charge separation and transfer to the reaction interface for hydrogen evolution as evidenced by electrochemical impedance spectroscopy (EIS) and charge carrier density calculation. Stability tests showed that the NiO nanoparticles loading content on Cu2O surface is a crucial parameter in this regard.

  7. Solar Photocatalytic Hydrogen Production from Water Using a Dual Bed Photosystem - Phase I Final Report and Phase II Proposal

    Energy Technology Data Exchange (ETDEWEB)

    Clovis A. Linkous; Darlene K. Slattery

    2000-09-11

    In this work we are attempting to perform the highly efficient storage of solar energy in the form of H{sub 2} via photocatalytic decomposition of water. While it has been demonstrated that H{sub 2} and O{sub 2} can be evolved from a single vessel containing a single suspended photocatalyst (Sayama 1994; 1997), we are attempting to perform net water-splitting by using two photocatalysts immobilized in separate containers, or beds. A schematic showing how the device would work is shown.

  8. Solar fuels

    Energy Technology Data Exchange (ETDEWEB)

    Bolton, J.R.

    1978-11-17

    The paper is concerned with (1) the thermodynamic and kinetic limits for the photochemical conversion and storage of solar energy as it is received on the earth's surface, and (2) the evaluation of a number of possible photochemical reactions with particular emphasis on the production of solar hydrogen from water. Procedures for generating hydrogen fuel are considered. Topics examined include the general requirements for a fuel-generation reaction, the photochemical reaction, limits on the conversion of light energy to chemical energy, an estimate of chemical storage efficiency, and the water decomposition reaction.

  9. Optical and passivating properties of hydrogenated amorphous silicon nitride deposited by plasma enhanced chemical vapour deposition for application on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wight, Daniel Nilsen

    2008-07-01

    Within this thesis, several important subjects related to the use of amorphous silicon nitride made by plasma enhanced chemical vapour deposition as an anti-reflective coating on silicon solar cells are presented. The first part of the thesis covers optical simulations to optimise single and double layer anti-reflective coatings with respect to optical performance when situated on a silicon solar cell. The second part investigates the relationship between important physical properties of silicon nitride films when deposited under different conditions. The optical simulations were either based on minimising the reflectance off a silicon nitride/silicon wafer stack or maximising the transmittance through the silicon nitride into the silicon wafer. The former method allowed consideration of the reflectance off the back surface of the wafer, which occurs typically at wavelengths above 1000 nm due to the transparency of silicon at these wavelengths. However, this method does not take into consideration the absorption occurring in the silicon nitride, which is negligible at low refractive indexes but quite significant when the refractive index increases above 2.1. For high-index silicon nitride films, the latter method is more accurate as it considers both reflectance and absorbance in the film to calculate the transmittance into the Si wafer. Both methods reach similar values for film thickness and refractive index for optimised single layer anti-reflective coatings, due to the negligible absorption occurring in these films. For double layer coatings, though, the reflectance based simulations overestimated the optimum refractive index for the bottom layer, which would have lead to excessive absorption if applied to real anti-reflective coatings. The experimental study on physical properties for silicon nitride films deposited under varying conditions concentrated on the estimation of properties important for its applications, such as optical properties, passivation

  10. Dispersed conductive polymer nanoparticles on graphitic carbon nitride for enhanced solar-driven hydrogen evolution from pure water.

    Science.gov (United States)

    Sui, Yi; Liu, Jinghai; Zhang, Yuewei; Tian, Xike; Chen, Wei

    2013-10-07

    Developing new methods to improve the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) for hydrogen (H₂) evolution has attracted intensive research interests. Here, we report that the g-C₃N₄ exhibits photocatalytic activity for H₂ evolution from pure water. And, the activity is dramatically improved by loading highly dispersed conductive polymer nanoparticles. The H₂ evolution rate increases up to 50 times for g-C₃N₄ with 1.5 wt% polypyrrole (PPy) nanoparticles on the surface. The reaction proceeding in a pure water system excludes the need for sacrificial agents. The role of the highly conductive PPy in enhancing H₂ evolution is as a surface junction to increase the number of photoinduced electrons, and to facilitate electron transfer to the interface.

  11. Quantitative autonomic testing.

    Science.gov (United States)

    Novak, Peter

    2011-07-19

    Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory should have a tilt table, ECG monitor, continuous noninvasive blood pressure monitor, respiratory monitor and a mean for evaluation of sudomotor domain. The software for recording and evaluation of autonomic tests is critical for correct evaluation of data. The presented protocol evaluates 3 major autonomic domains: cardiovagal, adrenergic and sudomotor. The tests include deep breathing, Valsalva maneuver, head-up tilt, and quantitative sudomotor axon test (QSART). The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores (CASS). Detailed protocol is provided highlighting essential aspects of testing with emphasis on proper data acquisition, obtaining the relevant parameters and unbiased evaluation of autonomic signals. The normative data and CASS algorithm for interpretation of results are provided as well.

  12. Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

    National Research Council Canada - National Science Library

    Huang, Bing; Deng, Hui-Xiong; Lee, Hoonkyung; Yoon, Mina; Sumpter, Bobby G; Liu, Feng; Smith, Sean C; Wei, Su-Huai

    2014-01-01

    ...) band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect...

  13. Semi-Autonomous Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Vision The Semi-Autonomous Systems Lab focuses on developing a comprehensive framework for semi-autonomous coordination of networked robotic systems. Semi-autonomous...

  14. Semi-Autonomous Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — VisionThe Semi-Autonomous Systems Lab focuses on developing a comprehensive framework for semi-autonomous coordination of networked robotic systems. Semi-autonomous...

  15. Wind, biomass, hydrogen: renewable energies; Vent, biomasse, hydrogene: energies renouvelables

    Energy Technology Data Exchange (ETDEWEB)

    Rakotosson, V.; Brousse, Th.; Guillemet, Ph.; Scudeller, Y.; Crosnier, O.; Dugas, R.; Favier, F.; Zhou, Y.; Taberna, P.M.; Simon, P.; Toupin, M.; Belanger, D.; Ngo, Ch.; Djamie, B.; Guyard, Ch.; Tamain, B.; Ruer, J.; Ungerer, Ph.; Bonal, J.; Flamant, G

    2007-06-15

    This press kit gathers a series of articles about renewable energies: the compared availabilities of renewable energy sources (comparison at a given time); offshore wind turbines (projects under development, cost optimisation); hydrogen for transports: present day situation (production, transport and storage, hydrogen conversion into mechanical energy, indirect use in biomass conversion); biomass: future carbon source (resource potential in France, pyrolysis and fermentation, development of biofuels and synthetic fuels, stakes for agriculture); beneficial standards for the heat pumps market (market organization and quality approach); collecting solar energy (solar furnaces and future solar power plants, hydrogen generation). (J.S.)

  16. Testing for autonomic neuropathy

    DEFF Research Database (Denmark)

    Hilsted, J

    1984-01-01

    Autonomic neuropathy is a common complication in long-term diabetes, about 30% of the patients showing measurable signs of autonomic dysfunction after 10 years duration of disease. The diagnosis is often difficult to establish because clinical symptoms generally occur late in the course...

  17. Hydrogen Implantation in Silicates: The role of solar wind in OH bond formation on the lunar surface

    Science.gov (United States)

    Schaible, Micah J; Baragiola, Raul

    2014-06-01

    Airless bodies in space such as the Moon, asteroids and interplanetary dust particles are subject to bombardment from energetic electrons and ions, ultraviolet photons, micrometeorites and cosmic rays. These bombarding particles modify optical, chemical and physical characteristics of the ices and minerals that make up these bodies in a process known as space weathering. In particular, solar wind protons implanted in silicate materials can participate in hydroxylation reactions with the oxygen to form OH. This mechanism has been suggested to explain a reported 3-14% absorption signal identified as OH on the surface of lunar soil grains and present in decreasing magnitude from polar to equatorial latitudes. With the goal of determining a precise OH formation rate due to H+ implantation in silicates, a series of experiments were carried out on terrestrial minerals as analogs to lunar and interstellar material.Experiments were carried out under UHV pressures (OH in thermally grown silicon oxide and San Carlos olivine, before and after irradiated with 1 - 5 keV H+ ions. The increase in Si-OH content due to irradiation was determined by subtracting the unirradiated spectra from the irradiated spectra. The implanted protons induced OH stretch absorptions in the mid-infrared peaked at 3673 cm-1 for SiO2 and 3570 cm-1 for olivine. The initial yield (OH formed per incident ion) was ~90% and the OH absorption band was found to saturate at implantation fluences of ~2x1017 H/cm2. Irradiation also modified the Si-O stretch band at ~1090 cm-1 (9.2 μm) causing an exponential decrease in the peak height with increasing fluence and the appearance of a silanol structure peaking at ~1030 cm-1. These measurements allow constraints to be placed on stellar wind contribution to observational and theoretical models of water on the lunar surface and on interstellar dust grains.

  18. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  19. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  20. Autonomous Infrastructure for Observatory Operations

    Science.gov (United States)

    Seaman, R.

    This is an era of rapid change from ancient human-mediated modes of astronomical practice to a vision of ever larger time domain surveys, ever bigger "big data", to increasing numbers of robotic telescopes and astronomical automation on every mountaintop. Over the past decades, facets of a new autonomous astronomical toolkit have been prototyped and deployed in support of numerous space missions. Remote and queue observing modes have gained significant market share on the ground. Archives and data-mining are becoming ubiquitous; astroinformatic techniques and virtual observatory standards and protocols are areas of active development. Astronomers and engineers, planetary and solar scientists, and researchers from communities as diverse as particle physics and exobiology are collaborating on a vast range of "multi-messenger" science. What then is missing?

  1. Autonomous Spacecraft Navigation With Pulsars

    CERN Document Server

    Becker, Werner; Jessner, Axel

    2013-01-01

    An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location, the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. The unique properties of pulsars make clear already today that such a navigation system will have its application in future astronautics. In this paper we describe the basic principle of spacecraft navigation using pulsars and report on the current development status of this novel technology.

  2. Heterostructured WS2 -MoS2 Ultrathin Nanosheets Integrated on CdS Nanorods to Promote Charge Separation and Migration and Improve Solar-Driven Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Reddy, D Amaranatha; Park, Hanbit; Ma, Rory; Kumar, D Praveen; Lim, Manho; Kim, Tae Kyu

    2017-04-10

    Solar-driven photocatalytic hydrogen evolution is important to bring solar-energy-to-fuel energy-conversion processes to reality. However, there is a lack of highly efficient, stable, and non-precious photocatalysts, and catalysts not designed completely with expensive noble metals have remained elusive, which hampers their large-scale industrial application. Herein, for the first time, a highly efficient and stable noble-metal-free CdS/WS2 -MoS2 nanocomposite was designed through a facile hydrothermal approach. When assessed as a photocatalyst for water splitting, the CdS/WS2 -MoS2 nanostructures exhibited remarkable photocatalytic hydrogen-evolution performance and impressive durability. An excellent hydrogen evolution rate of 209.79 mmol g(-1)  h(-1) was achieved under simulated sunlight irradiation, which is higher than the values for CdS/MoS2 (123.31 mmol g(-1)  h(-1) ) and CdS/WS2 nanostructures (169.82 mmol g(-1)  h(-1) ) and the expensive CdS/Pt benchmark catalyst (34.98 mmol g(-1)  h(-1) ). The apparent quantum yield reached 51.4 % at λ=425 nm in 5 h. Furthermore, the obtained hydrogen evolution rate was better than those of several noble-metal-free catalysts reported previously. The observed high rate of hydrogen evolution and remarkable stability may be a result of the ultrafast separation of photogenerated charge carriers and transport between the CdS nanorods and the WS2 -MoS2 nanosheets, which thus increases the number of electrons involved in hydrogen production. The proposed designed strategy is believed to potentially open a door to the design of advanced noble-metal-free photocatalytic materials for efficient solar-driven hydrogen production. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Photoelectrochemical hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Rocheleau, R.E.; Miller, E.; Misra, A. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-10-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. One promising option to meet this goal is direct photoelectrolysis in which light absorbed by semiconductor-based photoelectrodes produces electrical power internally to split water into hydrogen and oxygen. Under this program, direct solar-to-chemical conversion efficiencies as high as 7.8 % have been demonstrated using low-cost, amorphous-silicon-based photoelectrodes. Detailed loss analysis models indicate that solar-to-chemical conversion greater than 10% can be achieved with amorphous-silicon-based structures optimized for hydrogen production. In this report, the authors describe the continuing progress in the development of thin-film catalytic/protective coatings, results of outdoor testing, and efforts to develop high efficiency, stable prototype systems.

  4. Florida Hydrogen Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Block, David L

    2013-06-30

    The Florida Hydrogen Initiative (FHI) was a research, development and demonstration hydrogen and fuel cell program. The FHI program objectives were to develop Florida?s hydrogen and fuel cell infrastructure and to assist DOE in its hydrogen and fuel cell activities The FHI program funded 12 RD&D projects as follows: Hydrogen Refueling Infrastructure and Rental Car Strategies -- L. Lines, Rollins College This project analyzes strategies for Florida's early stage adaptation of hydrogen-powered public transportation. In particular, the report investigates urban and statewide network of refueling stations and the feasibility of establishing a hydrogen rental-car fleet based in Orlando. Methanol Fuel Cell Vehicle Charging Station at Florida Atlantic University ? M. Fuchs, EnerFuel, Inc. The project objectives were to design, and demonstrate a 10 kWnet proton exchange membrane fuel cell stationary power plant operating on methanol, to achieve an electrical energy efficiency of 32% and to demonstrate transient response time of less than 3 milliseconds. Assessment of Public Understanding of the Hydrogen Economy Through Science Center Exhibits, J. Newman, Orlando Science Center The project objective was to design and build an interactive Science Center exhibit called: ?H2Now: the Great Hydrogen Xchange?. On-site Reformation of Diesel Fuel for Hydrogen Fueling Station Applications ? A. Raissi, Florida Solar Energy Center This project developed an on-demand forecourt hydrogen production technology by catalytically converting high-sulfur hydrocarbon fuels to an essentially sulfur-free gas. The removal of sulfur from reformate is critical since most catalysts used for the steam reformation have limited sulfur tolerance. Chemochromic Hydrogen Leak Detectors for Safety Monitoring ? N. Mohajeri and N. Muradov, Florida Solar Energy Center This project developed and demonstrated a cost-effective and highly selective chemochromic (visual) hydrogen leak detector for safety

  5. Physics Simulation Software for Autonomous Propellant Loading and Gas House Autonomous System Monitoring

    Science.gov (United States)

    Regalado Reyes, Bjorn Constant

    2015-01-01

    1. Kennedy Space Center (KSC) is developing a mobile launching system with autonomous propellant loading capabilities for liquid-fueled rockets. An autonomous system will be responsible for monitoring and controlling the storage, loading and transferring of cryogenic propellants. The Physics Simulation Software will reproduce the sensor data seen during the delivery of cryogenic fluids including valve positions, pressures, temperatures and flow rates. The simulator will provide insight into the functionality of the propellant systems and demonstrate the effects of potential faults. This will provide verification of the communications protocols and the autonomous system control. 2. The High Pressure Gas Facility (HPGF) stores and distributes hydrogen, nitrogen, helium and high pressure air. The hydrogen and nitrogen are stored in cryogenic liquid state. The cryogenic fluids pose several hazards to operators and the storage and transfer equipment. Constant monitoring of pressures, temperatures and flow rates are required in order to maintain the safety of personnel and equipment during the handling and storage of these commodities. The Gas House Autonomous System Monitoring software will be responsible for constantly observing and recording sensor data, identifying and predicting faults and relaying hazard and operational information to the operators.

  6. Inherited autonomic neuropathies.

    Science.gov (United States)

    Axelrod, Felicia B; Hilz, Max J

    2003-12-01

    Inherited autonomic neuropathies are a rare group of disorders associated with sensory dysfunction. As a group they are termed the "hereditary sensory and autonomic neuropathies" (HSAN). Classification of the various autonomic and sensory disorders is ongoing. In addition to the numerical classification of four distinct forms proposed by Dyck and Ohta (1975), additional entities have been described. The best known and most intensively studied of the HSANs are familial dysautonomia (Riley-Day syndrome or HSAN type III) and congenital insensitivity to pain with anhidrosis (HSAN type IV). Diagnosis of the HSANs depends primarily on clinical examinations and specific sensory and autonomic assessments. Pathologic examinations are helpful in confirming the diagnosis and in differentiating between the different disorders. In recent years identification of specific genetic mutations for some disorders has aided diagnosis. Replacement or definitive therapies are not available for any of the disorders so that treatment remains supportive and directed toward specific symptoms.

  7. Autonomic cardiac innervation

    OpenAIRE

    Hasan, Wohaib

    2013-01-01

    Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targe...

  8. Autonomous Star Tracker Algorithms

    DEFF Research Database (Denmark)

    Betto, Maurizio; Jørgensen, John Leif; Kilsgaard, Søren

    1998-01-01

    Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances.......Proposal, in response to an ESA R.f.P., to design algorithms for autonomous star tracker operations.The proposal also included the development of a star tracker breadboard to test the algorithms performances....

  9. Photoelectrochemical water splitting in separate oxygen and hydrogen cells.

    Science.gov (United States)

    Landman, Avigail; Dotan, Hen; Shter, Gennady E; Wullenkord, Michael; Houaijia, Anis; Maljusch, Artjom; Grader, Gideon S; Rothschild, Avner

    2017-06-01

    Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyser architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional photoelectrochemical systems, enabling safe and potentially affordable solar hydrogen production.

  10. CHOOSING SOLAR PHOTOVOLTAIC PLANT

    Directory of Open Access Journals (Sweden)

    Vinnikov A. V.

    2015-04-01

    Full Text Available Promising is the direction and, above all, in matters of energy saving and energy efficiency of Autonomous systems of power supply, the use of renewable sources-newable energy as a major source of energy for consumers in remote areas. Here priority is given to solar energy. Since solar radiation can be change place not only in heat and electrical. The article contains three main structural schematics of electricity supply with solar power plants. The features of their work are disclosed, as well as an algorithm for calculating solar energy systems, the sequence of which is to define the required parameters, the daily energy consumption by consumers of electric power, the calculation capacity of the battery, the choice of the inverter and determining the area of solar batteries. The article reveals the conditions that affect the calculation of the PV system. It is shown that the greatest efficiency, including economic and reliability we have at combined (hybrid Autonomous system, which was carried out with both solar power and wind power and gas stations. The important matters of improving the reliability of solar systems are the introduction to the design of a new element of the base, and first and foremost, Autonomous inventors performed on a single-phase transformer with a rotating magnetic field

  11. Multilayer Dye Aggregation at Dye/TiO2 Interface via π…π Stacking and Hydrogen Bond and Its Impact on Solar Cell Performance: A DFT Analysis

    Science.gov (United States)

    Zhang, Lei; Liu, Xiaogang; Rao, Weifeng; Li, Jingfa

    2016-10-01

    Multilayer dye aggregation at the dye/TiO2 interface of dye-sensitized solar cells is probed via first principles calculations, using p-methyl red azo dye as an example. Our calculations suggest that the multilayer dye aggregates at the TiO2 surface can be stabilized by π…π stacking and hydrogen bond interactions. Compared with previous two-dimensional monolayer dye/TiO2 model, the multilayer dye aggregation model proposed in this study constructs a three-dimensional multilayer dye/TiO2 interfacial structure, and provides a better agreement between experimental and computational results in dye coverage and dye adsorption energy. In particular, a dimer forms by π…π stacking interactions between two neighboring azo molecules, while one of them chemisorbs on the TiO2 surface; a trimer may form by introducing one additional azo molecule on the dimer through a hydrogen bond between two carboxylic acid groups. Different forms of multilayer dye aggregates, either stabilized by π…π stacking or hydrogen bond, exhibit varied optical absorption spectra and electronic properties. Such variations could have a critical impact on the performance of dye sensitized solar cells.

  12. Solid electrolyte membranes and the system to produce hydrogen from thermally decomposed water by solar energy; Taiyo energy riyo ni yoru mizu no chokusetsu netsubunkai kara no suiso seizoyo

    Energy Technology Data Exchange (ETDEWEB)

    Nigara, K.; Watanabe, K.; Kawamura, K.; Kawada, T.; Mizusaki, J.; Ishigame, M. [Tohoku University, Sendai (Japan). Research Institute for Scientific Measurements

    1996-10-27

    For conversion of solar heat to transportable energy, hydrogen production by direct thermal decomposition of water using concentrated high-temperature solar heat was studied. Water vapor is injected into the tubular target with high melting point and high oxygen permeability at high temperature while heating the target by concentrated solar heat over 2000K. Oxygen in decomposed gas is discharged through an oxygen permeable membrane to extract hydrogen. Solid electrolyte is used as one of the target materials. Oxygen gas in the high-oxygen partial pressure site changes into oxygen ion by accepting two electrons at the target surface, and returns to neutral oxygen gas in the low-oxygen partial pressure site by discharging two electrons at the surface after permeation through oxygen vacancy. In the case of n-type solid electrolyte, to obtain constant permeation of a large amount of oxygen, flow of a large amount of electrons is indispensable in the opposite direction to oxygen ion. Among [(ZrO2)(1-x)(CeO2)x](0.9)(CaO)(0.1), materials of 0.4-0.5 in x seems to be useful as the target material. 7 refs., 7 figs.

  13. CdS nanoparticles sensitization of Al-doped ZnO nanorod array thin film with hydrogen treatment as an ITO/FTO-free photoanode for solar water splitting.

    Science.gov (United States)

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2012-10-25

    Aluminum-doped zinc oxide (AZO) nanorod array thin film with hydrogen treatment possesses the functions of transparent conducting oxide thin film and 1-D nanostructured semiconductor simultaneously. To enhance the absorption in the visible light region, it is sensitized by cadmium sulfide (CdS) nanoparticles which efficiently increase the absorption around 460 nm. The CdS nanoparticles-sensitized AZO nanorod array thin film with hydrogen treatment exhibits significantly improved photoelectrochemical property. After further heat treatment, a maximum short current density of 5.03 mA cm-2 is obtained under illumination. They not only are much higher than those without CdS nanoparticles sensitization and those without Al-doping and/or hydrogen treatment, but also comparable and even slightly superior to some earlier works for the CdS-sensitized zinc oxide nanorod array thin films with indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) as substrates. This demonstrated successfully that the AZO nanorod array thin film with hydrogen treatment is quite suitable as an ITO/FTO-free photoanode and has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

  14. Future: Solar energy. Zukunft: Sonnenenergie

    Energy Technology Data Exchange (ETDEWEB)

    Lange, V.

    1987-01-01

    The first chapter, 'Solar energy - more than just Utopia' deals with the following: Alternatives to nuclear energy problems of energy supply, solar energy use, commencement of the solar age in space, solar technology in the Federal Republic of Germany, solar collectors, wind power, energy from hydrogen. The second chapter 'Solar energy - its contribution to future energy supply' discusses prospects for the future (interviews with scientists and engineers). The third and last chapter gives practical hints (solar energy use: self-construction of solar plants). (HWJ).

  15. Autonomous Evolutionary Information Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Traditional information systems are passive, i.e., data orknowledge is created , retrieved, modified, updated, and deleted only in response to operations issued by users or application programs, and the systems only can execute queries or t ransactions explicitly submitted by users or application programs but have no ab ility to do something actively by themselves. Unlike a traditional information system serving just as a storehouse of data or knowledge and working passively a ccording to queries or transactions explicitly issued by users and application p rograms, an autonomous evolutionary information system serves as an autonomous a nd evolutionary partner of its users that discovers new knowledge from its datab ase or knowledge-base autonomously, cooperates with its users in solving proble m s actively by providing the users with advices, and has a certain mechanism to i mprove its own state of “knowing” and ability of “working”. This paper semi nall y defines what is an autonomous evolutionary information system, explain why aut onomous evolutionary information systems are needed, and presents some new issue s, fundamental considerations, and research directions in design and development of autonomous evolutionary information systems.

  16. Autonomic disturbances in narcolepsy.

    Science.gov (United States)

    Plazzi, Giuseppe; Moghadam, Keivan Kaveh; Maggi, Leonardo Serra; Donadio, Vincenzo; Vetrugno, Roberto; Liguori, Rocco; Zoccoli, Giovanna; Poli, Francesca; Pizza, Fabio; Pagotto, Uberto; Ferri, Raffaele

    2011-06-01

    Narcolepsy is a clinical condition characterized mainly by excessive sleepiness and cataplexy. Hypnagogic hallucinations and sleep paralysis complete the narcoleptic tetrad; disrupted night sleep, automatic behaviors and weight gain are also usual complaints. Different studies focus on autonomic changes or dysfunctions among narcoleptic patients, such as pupillary abnormalities, fainting spells, erectile dysfunction, night sweats, gastric problems, low body temperature, systemic hypotension, dry mouth, heart palpitations, headache and extremities dysthermia. Even if many studies lack sufficient standardization or their results have not been replicated, a non-secondary involvement of the autonomic nervous system in narcolepsy is strongly suggested, mainly by metabolic and cardiovascular findings. Furthermore, the recent discovery of a high risk for overweight and for metabolic syndrome in narcoleptic patients represents an important warning for clinicians in order to monitor and follow them up for their autonomic functions. We review here studies on autonomic functions and clinical disturbances in narcoleptic patients, trying to shed light on the possible contribute of alterations of the hypocretin system in autonomic pathophysiology.

  17. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

    Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

    2012-01-01

    The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experimen...

  18. Sustainable Electrochemical Hydrogen Production

    DEFF Research Database (Denmark)

    Kibsgaard, Jakob; Jaramillo, Thomas F.; Chorkendorff, Ib

    production is through electrochemical processes coupled to renewable energy sources such as wind or solar. The hydrogen evolution reaction (HER, 2H+ + 2e− → H2) constitutes half of the water splitting reaction. To increase process efficiency, active catalysts for the HER are needed. Currently platinum...

  19. Autonomous surveillance for biosecurity.

    Science.gov (United States)

    Jurdak, Raja; Elfes, Alberto; Kusy, Branislav; Tews, Ashley; Hu, Wen; Hernandez, Emili; Kottege, Navinda; Sikka, Pavan

    2015-04-01

    The global movement of people and goods has increased the risk of biosecurity threats and their potential to incur large economic, social, and environmental costs. Conventional manual biosecurity surveillance methods are limited by their scalability in space and time. This article focuses on autonomous surveillance systems, comprising sensor networks, robots, and intelligent algorithms, and their applicability to biosecurity threats. We discuss the spatial and temporal attributes of autonomous surveillance technologies and map them to three broad categories of biosecurity threat: (i) vector-borne diseases; (ii) plant pests; and (iii) aquatic pests. Our discussion reveals a broad range of opportunities to serve biosecurity needs through autonomous surveillance. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  20. Solar water splitting: efficiency discussion

    CERN Document Server

    Juodkazyte, Jurga; Sebeka, Benjaminas; Savickaja, Irena; Malinauskas, Tadas; Badokas, Kazimieras; Juodkazis, Kestutis; Juodkazis, Saulius

    2016-01-01

    The current state of the art in direct water splitting in photo-electrochemical cells (PECs) is presented together with: (i) a case study of water splitting using a simple solar cell with the most efficient water splitting electrodes and (ii) a detailed mechanism analysis. Detailed analysis of the energy balance and efficiency of solar hydrogen production are presented. The role of hydrogen peroxide formation as an intermediate in oxygen evolution reaction is newly revealed and explains why an oxygen evolution is not taking place at the thermodynamically expected 1.23 V potential. Solar hydrogen production with electrical-to-hydrogen conversion efficiency of 52% is demonstrated using a simple ~0.7%-efficient n-Si/Ni Schottky solar cell connected to a water electrolysis cell. This case study shows that separation of the processes of solar harvesting and electrolysis avoids photo-electrode corrosion and utilizes optimal electrodes for hydrogen and oxygen evolution reactions and achieves ~10% efficiency in light...

  1. Autonomous electrochromic assembly

    Energy Technology Data Exchange (ETDEWEB)

    Berland, Brian Spencer; Lanning, Bruce Roy; Stowell, Jr., Michael Wayne

    2015-03-10

    This disclosure describes system and methods for creating an autonomous electrochromic assembly, and systems and methods for use of the autonomous electrochromic assembly in combination with a window. Embodiments described herein include an electrochromic assembly that has an electrochromic device, an energy storage device, an energy collection device, and an electrochromic controller device. These devices may be combined into a unitary electrochromic insert assembly. The electrochromic assembly may have the capability of generating power sufficient to operate and control an electrochromic device. This control may occur through the application of a voltage to an electrochromic device to change its opacity state. The electrochromic assembly may be used in combination with a window.

  2. Simple Autonomous Chaotic Circuits

    Science.gov (United States)

    Piper, Jessica; Sprott, J.

    2010-03-01

    Over the last several decades, numerous electronic circuits exhibiting chaos have been proposed. Non-autonomous circuits with as few as two components have been developed. However, the operation of such circuits relies on the non-ideal behavior of the devices used, and therefore the circuit equations can be quite complex. In this paper, we present two simple autonomous chaotic circuits using only opamps and linear passive components. The circuits each use one opamp as a comparator, to provide a signum nonlinearity. The chaotic behavior is robust, and independent of nonlinearities in the passive components. Moreover, the circuit equations are among the algebraically simplest chaotic systems yet constructed.

  3. Photovoltaic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Hiser, H.W.; Memory, S.B.; Veziroglu, T.N.; Padin, J. [Univ. of Miami, Coral Gables, FL (United States)

    1996-10-01

    This is a new project, which started in June 1995, and involves photovoltaic hydrogen production as a fuel production method for the future. In order to increase the hydrogen yield, it was decided to use hybrid solar collectors to generate D.C. electricity, as well as high temperature steam for input to the electrolyzer. In this way, some of the energy needed to dissociate the water is supplied in the form of heat (or low grade energy), to generate steam, which results in a reduction of electrical energy (or high grade energy) needed. As a result, solar to hydrogen conversion efficiency is increased. In the above stated system, the collector location, the collector tracking sub-system (i.e., orientation/rotation), and the steam temperature have been taken as variables. Five locations selected - in order to consider a variety of latitudes, altitudes, cloud coverage and atmospheric conditions - are Atlanta, Denver, Miami, Phoenix and Salt Lake City. Plain PV and hybrid solar collectors for a stationary south facing system and five different collector rotation systems have been analyzed. Steam temperatures have been varied between 200{degrees}C and 1200{degrees}C. During the first year, solar to hydrogen conversion efficiencies have been considered. The results show that higher steam temperatures, 2 dimensional tracking system, higher elevations and dryer climates causes higher conversion efficiencies. Cost effectiveness of the sub-systems and of the overall system will be analyzed during the second year. Also, initial studies will be made of an advanced high efficiency hybrid solar hydrogen production system.

  4. Overview of the Autonomic Nervous System

    Science.gov (United States)

    ... be reversible or progressive. Anatomy of the autonomic nervous system The autonomic nervous system is the part of ... organs they connect with. Function of the autonomic nervous system The autonomic nervous system controls internal body processes ...

  5. Experimental Autonomous Vehicle Systems

    DEFF Research Database (Denmark)

    Ravn, Ole; Andersen, Nils Axel

    1998-01-01

    The paper describes the requirements for and a prototype configuration of a software architecture for control of an experimental autonomous vehicle. The test bed nature of the system is emphasised in the choice of architecture making re-configurability, data logging and extendability simple...

  6. Autonomous Hexapod Spider Robot

    DEFF Research Database (Denmark)

    Pandey, Nisha; Pandey, Bishwajeet; Hussain, Dil muhammed Akbar

    2017-01-01

    Robotics world is changing very rapidly in today’s scenario. One of its unique applications is hexapod robots (walking leg robots). These types of robots can walk on uneven surfaces and can be used for spying purpose in various forms of industries. This paper represents the autonomous feature of ...

  7. Autonomous component carrier selection

    DEFF Research Database (Denmark)

    Garcia, Luis Guilherme Uzeda; Pedersen, Klaus; Mogensen, Preben

    2009-01-01

    in local areas, basing our study case on LTE-Advanced. We present extensive network simulation results to demonstrate that a simple and robust interference management scheme, called autonomous component carrier selection allows each cell to select the most attractive frequency configuration; improving...

  8. Autonomous Forest Fire Detection

    NARCIS (Netherlands)

    Breejen, E. den; Breuers, M.; Cremer, F.; Kemp, R.A.W.; Roos, M.; Schutte, K.; Vries, J.S. de

    1998-01-01

    Forest fire detection is a very important issue in the pre-suppression process. Timely detection allows the suppression units to reach the fire in its initial stages and this will reduce the suppression costs considerably. The autonomous forest fire detection principle is based on temporal contrast

  9. 计算机控制太阳能光伏水制氢及储能发电系统的研究%Study on the Solar Photovoltaic Water Hydrogen Production and Energy Storage&Power Generation System Based on the Computer Control

    Institute of Scientific and Technical Information of China (English)

    秦天像; 任小勇; 杨天虎

    2015-01-01

    虽然太阳能、氢能利用技术有很多优势,但太阳能资源间歇性不稳定所带来的可靠性低的缺陷却影响着负载的连续使用. 太阳能光伏水制氢及储能发电系统能通过计算机控制提供稳定可靠的电能,具有很高的推广应用价值. 从太阳能光伏水制氢发电系统、计算机控制电解水制氢系统、储氢技术、氢能利用技术等方面,详细介绍了计算机控制太阳能光伏水制氢及储能发电系统的功能.%Although the solar energy and hydrogen energy utilization technologies have many advantages, the defect of low reliability caused by the intermittent instability of solar energy resources affects the continuous use of the load . The solar photovoltaic water hydrogen production and energy storage&power generation system, which can provide stable and reliable electricity through the computer control, has very high value of application. This paper introduces in detail the functions of the solar photovoltaic water hydrogen production and energy storage&power generation system from aspects of the solar photovoltaic water hydrogen power generation system, computer-based water electrolysis hydrogen production system, hydrogen storage technology, and hydrogen power utilization technology, etc.

  10. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  11. Thermospheric hydrogen response to increases in greenhouse gases

    Science.gov (United States)

    Nossal, S. M.; Qian, L.; Solomon, S. C.; Burns, A. G.; Wang, W.

    2016-04-01

    We investigated thermospheric hydrogen response to increase in greenhouse gases and the dependence of this response to solar activity, using a global mean version of the National Center for Atmospheric Research Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model. We separately doubled carbon dioxide (CO2) and methane (CH4) to study the influence of temperature and changes to source species for hydrogen. Our results indicate that both CO2 cooling and CH4 changes to the source species for hydrogen lead to predicted increases in the upper thermospheric hydrogen density. At 400 km, hydrogen increases ~30% under solar maximum and ~25% under solar minimum responding to doubling of CH4, indicating that hydrogen response to the source variation due to CH4 increase is relatively independent of solar activity. On the other hand, hydrogen response to doubling of CO2 highly depends on solar activity. At 400 km, doubling of CO2 results in an ~7% hydrogen increase at solar maximum, whereas it is ~25% at solar minimum. Consequently, at solar maximum, the predicted ~40% increase in atomic hydrogen in the upper thermosphere is primarily due to the source variation as a result of doubling of CH4, whereas at solar minimum, both cooling due to doubling of CO2 and the source variation due to doubling of CH4 have commensurate effects, resulting in an approximate 50% increase in the modeled upper thermospheric hydrogen.

  12. Recent work in advanced hydrogen production concepts

    Science.gov (United States)

    Lawson, D. D.

    1981-03-01

    The hydrogen photoelectrolytic conversion activity investigated the practicability of semiconductor electrolytic devises that use solar energy to decompose water into hydrogen and oxygen in an apparent single step process. The photocatalytic decomposition of inorganic hydrogen compounds; i.e., hydrobromic and hydriodic acids using rhodium organic bridge complexes were also studied. The feasibility of direct high temperature thermal decompositions of water with diffusion processes for separation of the equilibrium mixture of hydrogen and oxygen into usable energy sources was examined.

  13. Mobile Autonomous Humanoid Assistant

    Science.gov (United States)

    Diftler, M. A.; Ambrose, R. O.; Tyree, K. S.; Goza, S. M.; Huber, E. L.

    2004-01-01

    A mobile autonomous humanoid robot is assisting human co-workers at the Johnson Space Center with tool handling tasks. This robot combines the upper body of the National Aeronautics and Space Administration (NASA)/Defense Advanced Research Projects Agency (DARPA) Robonaut system with a Segway(TradeMark) Robotic Mobility Platform yielding a dexterous, maneuverable humanoid perfect for aiding human co-workers in a range of environments. This system uses stereo vision to locate human team mates and tools and a navigation system that uses laser range and vision data to follow humans while avoiding obstacles. Tactile sensors provide information to grasping algorithms for efficient tool exchanges. The autonomous architecture utilizes these pre-programmed skills to form human assistant behaviors. The initial behavior demonstrates a robust capability to assist a human by acquiring a tool from a remotely located individual and then following the human in a cluttered environment with the tool for future use.

  14. Using TiO 2 nanotubes to decompose water and produce hydrogen under solar light%利用 TiO2纳米管太阳能分解水制氢

    Institute of Scientific and Technical Information of China (English)

    古自勇; 刘练; 刘洋; 孙艳

    2015-01-01

    通过阳极氧化法在纯钛片表面氧化产生高度有序 TiO2纳米管,利用 TiO2纳米管在双室光电化学池光解水产生氢气,无需外加电压,直接通过光照射即可产生氢气。同时研究产氢效率、光电转化率与极距的关系,结果表明,在一定极距范围内,光电转化率和产氢效率都是随极距增加而增加,可通过改变极距提高产氢效率。%in this paper,TiO2 nanotubes with highly ordered array were prepared on the surface of pure titanium oxide films by anodic oxidation. Employing TiO2 nanotubes prepared,hydrogen was generated in the two - compartment photo electrochemical cell with no extra voltage supply other than solar energy. The relationship between polar distance and the efficiency of hydrogen generation was discussed. The result indicates that within certain ranges of polar distances,both photoelectric con-version and hydrogen generation rate go up with the increase of polar distance and the changing of the polar distance can improve the efficiency of hydrogen generation of TiO2 nanotubes.

  15. Autonomous robotic sweeper

    OpenAIRE

    Kržišnik, Domen

    2015-01-01

    There is already a wide range of personal/domestic robots on the market capable of performing various tasks. We haven't however been able to find any commercially available robots designed for effectively performing the task of backyard sweeping. This thesis presents the process and end result of planning, assembly and programming of an autonomous robot, capable of performing the above mentioned task. We first analyze robots with similar functions, including robotic vacuum cleaners and lawn m...

  16. Autonomous Undersea Observations

    Science.gov (United States)

    2016-06-13

    less expensive sensor systems for a variety of applications, including measurement of physical characteristics of the ocean, threat detection, and...multiple autonomous environmental sensors within an acoustic modem-based infrastructure capable of communicating to and from the sensors and to and...networks, and telesonar with high speed platforms. This effort is concentrating on the development and demonstration of the two modem- based sensors . We

  17. Trigeminal autonomic cephalalgias.

    Science.gov (United States)

    Eller, M; Goadsby, P J

    2016-01-01

    The trigeminal autonomic cephalalgias (TACs) are a group of primary headache disorders characterised by lateralized symptoms: prominent headache and ipsilateral cranial autonomic features, such as conjunctival injection, lacrimation and rhinorrhea. The TACs are: cluster headache (CH), paroxysmal hemicrania (PH), short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)/short-lasting neuralgiform headache attacks with cranial autonomic features (SUNA) and hemicrania continua (HC). Their diagnostic criteria are outlined in the International Classification of Headache Disorders, third edition-beta (ICHD-IIIb). These conditions are distinguished by their attack duration and frequency, as well as response to treatment. HC is continuous and by definition responsive to indomethacin. The main differential when considering this headache is chronic migraine. Other TACs are remarkable for their short duration and must be distinguished from other short-lasting painful conditions, such as trigeminal neuralgia and primary stabbing headache. Cluster headache is characterised by exquisitely painful attacks that occur in discrete episodes lasting 15-180 min a few times a day. In comparison, PH occurs more frequently and is of shorter duration, and like HC is responsive to indomethacin. SUNCT/SUNA is the shortest duration and highest frequency TAC; attacks can occur over a hundred times every day.

  18. Hydrogen production by solar energy. Final report of the integrated project HYSOL (2002-2004); Production d'hydrogene par energie solaire. Rapport Final du Projet Integre HYSOL (2002-2004)

    Energy Technology Data Exchange (ETDEWEB)

    Flamant, G.

    2004-07-01

    The HYSOL project aims to study three thermal processes using the solar energy at temperatures of more than 1000 C: hydrocarbons cracking, non catalytic reforming at high temperature and water decomposition by thermal-chemical cycles. This report presents the HYSOL project and the main results and gives a special part to the methane cracking. (A.L.B.)

  19. Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2014-02-01

    Full Text Available In this study, silicon nitride (SiNx thin films were deposited on polyimide (PI substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD system. The gallium-doped zinc oxide (GZO thin films were deposited on PI and SiNx/PI substrates at room temperature (RT, 100 and 200 °C by radio frequency (RF magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~1000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI.

  20. The hydrogen issue.

    Science.gov (United States)

    Armaroli, Nicola; Balzani, Vincenzo

    2011-01-17

    Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution

  1. Thermochemical reactivity of 5–15 mol% Fe, Co, Ni, Mn-doped cerium oxides in two-step water-splitting cycle for solar hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Gokon, Nobuyuki, E-mail: ngokon@eng.niigata-u.ac.jp [Center for Transdisciplinary Research, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Suda, Toshinori [Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan); Kodama, Tatsuya [Department of Chemistry & Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

    2015-10-10

    Highlights: • 5–15 mol% M-doped ceria are examined for thermochemical two-step water-splitting. • 5 mol% Fe- and Co-doped ceria have stoichiometric production of oxygen and hydrogen. • 10–15 mol% Fe- and Mn-doped ceria showed near-stoichiometric production. - Abstract: The thermochemical two-step water-splitting cycle using transition element-doped cerium oxide (M–CeO{sub 2−δ}; M = Fe, Co, Ni, Mn) powders was studied for hydrogen production from water. The oxygen/hydrogen productivity and repeatability of M–CeO{sub 2−δ} materials with M doping contents in the 5–15 mol% range were examined using a thermal reduction (TR) temperature of 1500 °C and water decomposition (WD) temperatures in the 800–1150 °C range. The temperature, steam partial pressure, and steam flow rate in the WD step had an impact on the hydrogen productivity and production rate. 5 mol% Fe- and Co-doped CeO{sub 2−δ} enhances hydrogen productivity by up to 25% on average compared to undoped CeO{sub 2}, and shows stable repeatability of stoichiometric oxygen and hydrogen production for the cyclic thermochemical two-step water-splitting reaction. In addition, 5 mol% Mn-doped CeO{sub 2−δ}, 10 and 15 mol% Fe- and Mn-doped CeO{sub 2−δ} show near stoichiometric reactivities.

  2. Hierarchical 3D ZnIn2S4/graphene nano-heterostructures: their in situ fabrication with dual functionality in solar hydrogen production and as anodes for lithium ion batteries.

    Science.gov (United States)

    Kale, Sayali B; Kalubarme, Ramchandra S; Mahadadalkar, Manjiri A; Jadhav, Harsharaj S; Bhirud, Ashwini P; Ambekar, Jalinder D; Park, Chan-Jin; Kale, Bharat B

    2015-12-21

    Hierarchical 3D ZnIn2S4/graphene (ZnIn2S4/Gr) nano-heterostructures were successfully synthesized using an in-situ hydrothermal method. The dual functionality of these nano-heterostructures i.e. for solar hydrogen production and lithium ion batteries has been demonstrated for the first time. The ZnIn2S4/Gr nano-heterostructures were optimized by varying the concentrations of graphene for utmost hydrogen production. An inspection of the structure shows the existence of layered hexagonal ZnIn2S4 wrapped in graphene. The reduction of graphene oxide (GO) to graphene was confirmed by Raman and XPS analyses. The morphological analysis demonstrated that ultrathin ZnIn2S4 nanopetals are dispersed on graphene sheets. The optical study reveals the extended absorption edge to the visible region due to the presence of graphene and hence is used as a photocatalyst to transform H2S into eco-friendly hydrogen using solar light. The ZnIn2S4/Gr nano-heterostructure that is comprised of graphene and ZnIn2S4 in a weight ratio of 1 : 99 exhibits enhanced photocatalytically stable hydrogen production i.e. ∼6365 μmole h(-1) under visible light irradiation using just 0.2 g of nano-heterostructure, which is much higher as compared to bare hierarchical 3D ZnIn2S4. The heightened photocatalytic activity is attributed to the enhanced charge carrier separation due to graphene which acts as an excellent electron collector and transporter. Furthermore, the usage of nano-heterostructures and pristine ZnIn2S4 as anodes in lithium ion batteries confers the charge capacities of 590 and 320 mA h g(-1) after 220 cycles as compared to their initial reversible capacities of 645 and 523 mA h g(-1), respectively. These nano-heterostructures show high reversible capacity, excellent cycling stability, and high-rate capability indicating their potential as promising anode materials for LIBs. The excellent performance is due to the nanostructuring of ZnIn2S4 and the presence of a graphene layer, which

  3. Florida Hydrogen Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Block, David L

    2013-06-30

    The Florida Hydrogen Initiative (FHI) was a research, development and demonstration hydrogen and fuel cell program. The FHI program objectives were to develop Florida?s hydrogen and fuel cell infrastructure and to assist DOE in its hydrogen and fuel cell activities The FHI program funded 12 RD&D projects as follows: Hydrogen Refueling Infrastructure and Rental Car Strategies -- L. Lines, Rollins College This project analyzes strategies for Florida's early stage adaptation of hydrogen-powered public transportation. In particular, the report investigates urban and statewide network of refueling stations and the feasibility of establishing a hydrogen rental-car fleet based in Orlando. Methanol Fuel Cell Vehicle Charging Station at Florida Atlantic University ? M. Fuchs, EnerFuel, Inc. The project objectives were to design, and demonstrate a 10 kWnet proton exchange membrane fuel cell stationary power plant operating on methanol, to achieve an electrical energy efficiency of 32% and to demonstrate transient response time of less than 3 milliseconds. Assessment of Public Understanding of the Hydrogen Economy Through Science Center Exhibits, J. Newman, Orlando Science Center The project objective was to design and build an interactive Science Center exhibit called: ?H2Now: the Great Hydrogen Xchange?. On-site Reformation of Diesel Fuel for Hydrogen Fueling Station Applications ? A. Raissi, Florida Solar Energy Center This project developed an on-demand forecourt hydrogen production technology by catalytically converting high-sulfur hydrocarbon fuels to an essentially sulfur-free gas. The removal of sulfur from reformate is critical since most catalysts used for the steam reformation have limited sulfur tolerance. Chemochromic Hydrogen Leak Detectors for Safety Monitoring ? N. Mohajeri and N. Muradov, Florida Solar Energy Center This project developed and demonstrated a cost-effective and highly selective chemochromic (visual) hydrogen leak detector for safety

  4. Autonomic Function in Neurodegenerative Diseases

    DEFF Research Database (Denmark)

    Sørensen, Gertrud Laura; Jennum, Poul Jørgen

    2013-01-01

    , which includes the cardiac centre and controls autonomic functions, and therefore autonomic dysfunction may be experienced early in the disease course. Sleep disturbances are also common non-motor complications of PD, and therefore PD patients undergo polysomnography at the Danish Center for Sleep...... Medicine to assess the sleep disturbances. The aim of this PhD dissertation was to: 1) Develop a method to investigate autonomic changes during sleep in neurodegenerative diseases, and apply this method on PD, iRBD and narcolepsy patients to evaluate the autonomic function in these diseases. 2) Validate...... the method by applying standardized methods to measure the autonomic function based on heart rate variability (HRV) measures. 3) Based on the results, assess the validity of autonomic dysfunction as an early marker of a neurodegenerative disease. 4) Evaluate the influence of hypocretin loss in narcolepsy...

  5. Autonomic disorders in multiple sclerosis.

    Science.gov (United States)

    Lensch, E; Jost, W H

    2011-01-01

    Multiple sclerosis is an inflammatory disease leading to disseminated lesions of the central nervous system resulting in both somatomotor and autonomic disturbances. These involve the central centers of the autonomic nervous system, as well as the automatic control and pathway systems. All autonomic functions may be disordered individually or in combined form. There is no other disease with a clinical picture so multifaceted. Besides cardiovascular dysfunctions disorders of bladder and rectum have become apparent. Somatomotor and autonomic disturbances occur with similar frequency; however the focused exam often heavily favors somatomotor symptoms. Autonomic disturbances should primarily be taken into account on history taking and clinical examination. Individual diagnosis and treatment is a secondary feature. Impairments of the autonomic nervous systems in multiple sclerosis are frequently overlooked.

  6. Autonomic Disorders in Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    E. Lensch

    2011-01-01

    Full Text Available Multiple sclerosis is an inflammatory disease leading to disseminated lesions of the central nervous system resulting in both somatomotor and autonomic disturbances. These involve the central centers of the autonomic nervous system, as well as the automatic control and pathway systems. All autonomic functions may be disordered individually or in combined form. There is no other disease with a clinical picture so multifaceted. Besides cardiovascular dysfunctions disorders of bladder and rectum have become apparent. Somatomotor and autonomic disturbances occur with similar frequency; however the focused exam often heavily favors somatomotor symptoms. Autonomic disturbances should primarily be taken into account on history taking and clinical examination. Individual diagnosis and treatment is a secondary feature. Impairments of the autonomic nervous systems in multiple sclerosis are frequently overlooked.

  7. Hydrogenated amorphous silicon p-i-n solar cells deposited under well controlled ion bombardment using pulse-shaped substrate biasing

    NARCIS (Netherlands)

    Wank, M. A.; van Swaaij, R.; R. van de Sanden,; Zeman, M.

    2012-01-01

    We applied pulse-shaped biasing (PSB) to the expanding thermal plasma deposition of intrinsic hydrogenated amorphous silicon layers at substrate temperatures of 200 degrees C and growth rates of about 1?nm/s. Fourier transform infrared spectroscopy of intrinsic films showed a densification with incr

  8. Catecholamines and diabetic autonomic neuropathy

    DEFF Research Database (Denmark)

    Hilsted, J

    1995-01-01

    In diabetic patients with autonomic neuropathy plasma noradrenaline concentration, used as an index of sympathetic nervous activity, is low. This decrease is, however, only found in patients with a long duration of diabetes with clinically severe autonomic neuropathy. This apparent insensitivity...... of plasma catecholamine measurements is not due to changes in the clearance of catecholamines in diabetic autonomic neuropathy. The physiological responses to infused adrenaline and to noradrenaline are enhanced, for noradrenaline mainly cardiovascular responses. Adrenoceptors (alpha and beta adrenoceptors...

  9. Simulation studies on the effect of a buffer layer on the external parameters of hydrogenated amorphous silicon –– solar cells

    Indian Academy of Sciences (India)

    K Rajeev Kumar; M Zeman

    2008-10-01

    Device modeling of –– junction amorphous silicon solar cells has been carried out using the amorphous semiconductor analysis (ASA) simulation programme. The aim of the study was to explain the role of a buffer layer in between the - and -layers of the –– solar cell on the external parameters such as dark current density and open circuit voltage. Investigations based on the simulation of dark – characteristics revealed that as the buffer layer thickness increases the dark current for a given voltage decreases.

  10. Saga of hydrogen civilization

    Energy Technology Data Exchange (ETDEWEB)

    Veziroglu, T.N. [Clean Energy Research Inst., Univ. of Miami, Coral Gables, Florida (United States)

    2009-07-01

    'Full text': Fossil fuels (i.e., petroleum, natural gas and coal), which meet most of the world's energy demand today, are being depleted quickly. Also, their combustion products are causing global problems such as the greenhouse effect, ozone layer depletion, acid rains and pollution, all of which are posing great danger for our environment and eventually for the life on our planet. Many engineers and scientists agree that the solution to these global problems would be to replace the existing fossil fuel system by the hydrogen energy system. Hydrogen is a very efficient and clean fuel. Its combustion will produce no greenhouse gases, no ozone layer depleting chemicals, and little or no acid rain ingredients and pollution. Hydrogen, produced from renewable energy (e.g., solar) sources, would result in a permanent energy system which we would never have to change. However, there are other energy systems proposed for the post-petroleum era, such as a synthetic fossil fuel system. In this system, synthetic gasoline and synthetic natural gas will be produced using abundant deposits of coal. In a way, this will ensure the continuation of the present fossil fuel system. The two possible energy systems for the post-fossil fuel era (i.e., the solar-hydrogen energy system and the synthetic fossil fuel system) are compared with the present fossil fuel system by taking into consideration production costs, environmental damages and utilization efficiencies. The results indicate that the solar-hydrogen energy system is the best energy system to ascertain a sustainable future, and it should replace the fossil fuel system before the end of the 21st century. (author)

  11. Jam avoidance with autonomous systems

    CERN Document Server

    Tordeux, Antoine

    2016-01-01

    Many car-following models are developed for jam avoidance in highways. Two mechanisms are used to improve the stability: feedback control with autonomous models and increasing of the interaction within cooperative ones. In this paper, we compare the linear autonomous and collective optimal velocity (OV) models. We observe that the stability is significantly increased by adding predecessors in interaction with collective models. Yet autonomous and collective approaches are close when the speed difference term is taking into account. Within the linear OV models tested, the autonomous models including speed difference are sufficient to maximise the stability.

  12. Robotics and Autonomous Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides an environment for developing and evaluating intelligent software for both actual and simulated autonomous vehicles. Laboratory computers provide...

  13. Acetylene bubble-powered autonomous capsules: towards in situ fuel.

    Science.gov (United States)

    Moo, James Guo Sheng; Wang, Hong; Pumera, Martin

    2014-12-28

    A fuel-free autonomous self-propelled motor is illustrated. The motor is powered by the chemistry of calcium carbide and utilising water as a co-reactant, through a polymer encapsulation strategy. Expulsion of acetylene bubbles powers the capsule motor. This is an important step, going beyond the toxic hydrogen peroxide fuel used normally, to find alternative propellants for self-propelled machines.

  14. Autonomous mobile robot teams

    Science.gov (United States)

    Agah, Arvin; Bekey, George A.

    1994-01-01

    This paper describes autonomous mobile robot teams performing tasks in unstructured environments. The behavior and the intelligence of the group is distributed, and the system does not include a central command base or leader. The novel concept of the Tropism-Based Cognitive Architecture is introduced, which is used by the robots in order to produce behavior transforming their sensory information to proper action. The results of a number of simulation experiments are presented. These experiments include worlds where the robot teams must locate, decompose, and gather objects, and defend themselves against hostile predators, while navigating around stationary and mobile obstacles.

  15. Compensation of decreased ion energy by increased hydrogen dilution in plasma deposition of thin film silicon solar cells at low substrate temperatures

    NARCIS (Netherlands)

    A.D. Verkerk; M.M. de Jong; J.K. Rath; M. Brinza; R.E.I. Schropp; W.J. Goedheer; V.V. Krzhizhanovskaya; Y.E. Gorbachev; K.E. Orlov; E.M. Khilkevitch; A.S. Smirnov

    2008-01-01

    In order to deposit thin film silicon solar cells on plastics and papers, the deposition process needs to be adapted for low deposition temperatures. In a very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) process, both the gas phase and the surface processes are affected by l

  16. Purdue Hydrogen Systems Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Jay P Gore; Robert Kramer; Timothee L Pourpoint; P. V. Ramachandran; Arvind Varma; Yuan Zheng

    2011-12-28

    The Hydrogen Systems Laboratory in a unique partnership between Purdue University's main campus in West Lafayette and the Calumet campus was established and its capabilities were enhanced towards technology demonstrators. The laboratory engaged in basic research in hydrogen production and storage and initiated engineering systems research with performance goals established as per the USDOE Hydrogen, Fuel Cells, and Infrastructure Technologies Program. In the chemical storage and recycling part of the project, we worked towards maximum recycling yield via novel chemical selection and novel recycling pathways. With the basic potential of a large hydrogen yield from AB, we used it as an example chemical but have also discovered its limitations. Further, we discovered alternate storage chemicals that appear to have advantages over AB. We improved the slurry hydrolysis approach by using advanced slurry/solution mixing techniques. We demonstrated vehicle scale aqueous and non-aqueous slurry reactors to address various engineering issues in on-board chemical hydrogen storage systems. We measured the thermal properties of raw and spent AB. Further, we conducted experiments to determine reaction mechanisms and kinetics of hydrothermolysis in hydride-rich solutions and slurries. We also developed a continuous flow reactor and a laboratory scale fuel cell power generation system. The biological hydrogen production work summarized as Task 4.0 below, included investigating optimal hydrogen production cultures for different substrates, reducing the water content in the substrate, and integrating results from vacuum tube solar collector based pre and post processing tests into an enhanced energy system model. An automated testing device was used to finalize optimal hydrogen production conditions using statistical procedures. A 3 L commercial fermentor (New Brunswick, BioFlo 115) was used to finalize testing of larger samples and to consider issues related to scale up

  17. Learning for Autonomous Navigation

    Science.gov (United States)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Robotic ground vehicles for outdoor applications have achieved some remarkable successes, notably in autonomous highway following (Dickmanns, 1987), planetary exploration (1), and off-road navigation on Earth (1). Nevertheless, major challenges remain to enable reliable, high-speed, autonomous navigation in a wide variety of complex, off-road terrain. 3-D perception of terrain geometry with imaging range sensors is the mainstay of off-road driving systems. However, the stopping distance at high speed exceeds the effective lookahead distance of existing range sensors. Prospects for extending the range of 3-D sensors is strongly limited by sensor physics, eye safety of lasers, and related issues. Range sensor limitations also allow vehicles to enter large cul-de-sacs even at low speed, leading to long detours. Moreover, sensing only terrain geometry fails to reveal mechanical properties of terrain that are critical to assessing its traversability, such as potential for slippage, sinkage, and the degree of compliance of potential obstacles. Rovers in the Mars Exploration Rover (MER) mission have got stuck in sand dunes and experienced significant downhill slippage in the vicinity of large rock hazards. Earth-based off-road robots today have very limited ability to discriminate traversable vegetation from non-traversable vegetation or rough ground. It is impossible today to preprogram a system with knowledge of these properties for all types of terrain and weather conditions that might be encountered.

  18. Towards autonomous vehicular clouds

    Directory of Open Access Journals (Sweden)

    Stephan Olariu

    2011-09-01

    Full Text Available The dawn of the 21st century has seen a growing interest in vehicular networking and its myriad potential applications. The initial view of practitioners and researchers was that radio-equipped vehicles could keep the drivers informed about potential safety risks and increase their awareness of road conditions. The view then expanded to include access to the Internet and associated services. This position paper proposes and promotes a novel and more comprehensive vision namely, that advances in vehicular networks, embedded devices and cloud computing will enable the formation of autonomous clouds of vehicular computing, communication, sensing, power and physical resources. Hence, we coin the term, autonomous vehicular clouds (AVCs. A key feature distinguishing AVCs from conventional cloud computing is that mobile AVC resources can be pooled dynamically to serve authorized users and to enable autonomy in real-time service sharing and management on terrestrial, aerial, or aquatic pathways or theaters of operations. In addition to general-purpose AVCs, we also envision the emergence of specialized AVCs such as mobile analytics laboratories. Furthermore, we envision that the integration of AVCs with ubiquitous smart infrastructures including intelligent transportation systems, smart cities and smart electric power grids will have an enormous societal impact enabling ubiquitous utility cyber-physical services at the right place, right time and with right-sized resources.

  19. Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    None

    2014-09-01

    This 2-page fact sheet provides a brief introduction to hydrogen production technologies. Intended for a non-technical audience, it explains how different resources and processes can be used to produce hydrogen. It includes an overview of research goals as well as “quick facts” about hydrogen energy resources and production technologies.

  20. Hydrogen storage

    NARCIS (Netherlands)

    Peters, C.J.; Sloan, E.D.

    2005-01-01

    The invention relates to the storage of hydrogen. The invention relates especially to storing hydrogen in a clathrate hydrate. The clathrate hydrate according to the present invention originates from a composition, which comprises water and hydrogen, as well as a promotor compound. The promotor comp

  1. Dual function photocatalysis of cyano-bridged heteronuclear metal complexes for water oxidation and two-electron reduction of dioxygen to produce hydrogen peroxide as a solar fuel.

    Science.gov (United States)

    Aratani, Yusuke; Suenobu, Tomoyoshi; Ohkubo, Kei; Yamada, Yusuke; Fukuzumi, Shunichi

    2017-03-25

    The photocatalytic production of hydrogen peroxide from water and dioxygen under visible light irradiation was made possible by using polymeric cyano-bridged heteronuclear metal complexes (M(II)[Ru(II)(CN)4(bpy)]; M(II) = Ni(II), Fe(II) and Mn(II)), where the photocatalytic two-electron reduction of O2 and water oxidation were catalysed by the Ru and M(II) moieties, respectively.

  2. Autonomous Learner Model Resource Book

    Science.gov (United States)

    Betts, George T.; Carey, Robin J.; Kapushion, Blanche M.

    2016-01-01

    "Autonomous Learner Model Resource Book" includes activities and strategies to support the development of autonomous learners. More than 40 activities are included, all geared to the emotional, social, cognitive, and physical development of students. Teachers may use these activities and strategies with the entire class, small groups, or…

  3. Proportionality and Autonomous Weapons Systems

    NARCIS (Netherlands)

    van den Boogaard, J.

    2015-01-01

    Given the swift technologic development, it may be expected that the availability of the first truly autonomous weapons systems is fast approaching. Once they are deployed, these weapons will use artificial intelligence to select and attack targets without further human intervention. Autonomous

  4. Proportionality and Autonomous Weapons Systems

    NARCIS (Netherlands)

    van den Boogaard, J.

    2015-01-01

    Given the swift technologic development, it may be expected that the availability of the first truly autonomous weapons systems is fast approaching. Once they are deployed, these weapons will use artificial intelligence to select and attack targets without further human intervention. Autonomous weap

  5. Photovoltaic-wind hybrid autonomous generation systems in Mongolia

    Energy Technology Data Exchange (ETDEWEB)

    Dei, Tsutomu; Ushiyama, Izumi

    2005-01-01

    Two hybrid stand-alone (autonomous) power systems, each with wind and PV generation, were studied as installed at health clinics in semi-desert and mountainous region in Mongolia. Meteorological and system operation parameters, including power output and the consumption of the system, were generally monitored by sophisticated monitoring. However, where wind and solar site information was lacking, justifiable estimates were made. The results show that there is a seasonal complementary relationship between wind and solar irradiation in Tarot Sum. The users understood the necessity of Demand Side Management of isolated wind-PV generation system through technology transfer seminars and actually executed DSM at both sites. (author)

  6. Evolutionary Autonomous Health Monitoring System (EAHMS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For supporting NASA's Robotics, Tele-Robotics and Autonomous Systems Roadmap, we are proposing the "Evolutionary Autonomous Health Monitoring System" (EAHMS) for...

  7. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere I. Continuous Emission and Condensed Matter Within the Chromosphere

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The continuous spectrum of the solar photosphere stands as the paramount observation with regard to the condensed nature of the solar body. Studies relative to Kirchhoff’s law of thermal emission (e.g. Robitaille P.-M. Kirchhoff’s law of thermal emission: 150 years. Progr. Phys., 2009, v. 4, 3–13. and a detailed analysis of the stellar opacity problem (Robitaille P.M. Stellar opacity: The Achilles’ heel of the gaseous Sun. Progr. Phys., 2011, v. 3, 93–99 have revealed that gaseous models remain unable to properly account for the generation of this spectrum. Therefore, it can be stated with certainty that the photosphere is comprised of condensed matter. Beyond the solar surface, the chromospheric layer of the Sun also generates a weak continuous spectrum in the visible region. This emission exposes the presence of material in the condensed state. As a result, above the level of the photosphere, matter exists in both gaseous and condensed forms, much like within the atmosphere of the Earth. The continuous visible spectrum associated with the chromosphere provides the twenty-sixth line of evidence that the Sun is condensed matter.

  8. Solar water splitting: efficiency discussion

    OpenAIRE

    Juodkazyte, Jurga; Seniutinas, Gediminas; Sebeka, Benjaminas; Savickaja, Irena; Malinauskas, Tadas; Badokas, Kazimieras; Juodkazis, Kestutis; Juodkazis, Saulius

    2016-01-01

    The current state of the art in direct water splitting in photo-electrochemical cells (PECs) is presented together with: (i) a case study of water splitting using a simple solar cell with the most efficient water splitting electrodes and (ii) a detailed mechanism analysis. Detailed analysis of the energy balance and efficiency of solar hydrogen production are presented. The role of hydrogen peroxide formation as an intermediate in oxygen evolution reaction is newly revealed and explains why a...

  9. Autonomous movement of platinum-loaded stomatocytes.

    Science.gov (United States)

    Wilson, Daniela A; Nolte, Roeland J M; van Hest, Jan C M

    2012-02-26

    Polymer stomatocytes are bowl-shaped structures of nanosize dimensions formed by the controlled deformation of polymer vesicles. The stable nanocavity and strict control of the opening are ideal for the physical entrapment of nanoparticles which, when catalytically active, can turn the stomatocyte morphology into a nanoreactor. Herein we report an approach to generate autonomous movement of the polymer stomatocytes by selectively entrapping catalytically active platinum nanoparticles within their nanocavities and subsequently using catalysis as a driving force for movement. Hydrogen peroxide is free to access the inner stomatocyte cavity, where it is decomposed by the active catalyst (the entrapped platinum nanoparticles) into oxygen and water. This generates a rapid discharge, which induces thrust and directional movement. The design of the platinum-loaded stomatocytes resembles a miniature monopropellant rocket engine, in which the controlled opening of the stomatocytes directs the expulsion of the decomposition products away from the reaction chamber (inner stomatocyte cavity).

  10. Hydrogen energy systems technology study

    Science.gov (United States)

    Kelley, J. H.

    1975-01-01

    The paper discusses the objectives of a hydrogen energy systems technology study directed toward determining future demand for hydrogen based on current trends and anticipated new uses and identifying the critical research and technology advancements required to meet this need with allowance for raw material limitations, economics, and environmental effects. Attention is focused on historic production and use of hydrogen, scenarios used as a basis for projections, projections of energy sources and uses, supply options, and technology requirements and needs. The study found more than a billion dollar annual usage of hydrogen, dominated by chemical-industry needs, supplied mostly from natural gas and petroleum feedstocks. Evaluation of the progress in developing nuclear fusion and solar energy sources relative to hydrogen production will be necessary to direct the pace and character of research and technology work in the advanced water-splitting areas.

  11. Autonomous Gaussian Decomposition

    CERN Document Server

    Lindner, Robert R; Murray, Claire E; Stanimirović, Snežana; Babler, Brian L; Heiles, Carl; Hennebelle, Patrick; Goss, W M; Dickey, John

    2014-01-01

    We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21cm absorption spectra from the 21cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the HI line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the up...

  12. Solar-light-driven photo-electrolysis and production of hydrogen and oxygen - Annual report 2006; Photolyse de l'eau et production d'hydrogene et d'oxygene au moyen de l'energie solaire - Rapport annuel 2006

    Energy Technology Data Exchange (ETDEWEB)

    Augustynski, J.; Jorand Sartoretti, C.; Bilecka, I.; Solarska, R.

    2006-11-15

    We pursued studies of solar-light-driven photo-electrolysis cell employing semi-transparent WO{sub 3} photo anode. The stability of the photo anode in different electrolytes has been evaluated. Long term photo-electrolysis runs allowed us to identify solutions of sodium chloride as being the optimum electrolytes for water cleavage in hydrogen and oxygen, with some amount of chlorine formed as a by-product. In particular, the photo-electrolysis of a 0.5 M solution of sodium chloride, which is a composition close to sea water, results in the formation of about 20% of chlorine at the WO{sub 3} photo anode with oxygen remaining the main product. Thus, the sea water appears as an abundant, non-toxic electrolyte suitable for massive hydrogen production via photo-electrolysis. Charge and mass transport are among the main factors determining the efficiency of nanostructured semiconducting photo-electrodes. In contrast with the prevailing current opinion, our results show that it is the migrational/diffusional transport within electrolyte filling the pores of the photo-electrode and not the electron diffusion across the semiconductor matrix which controls the photocurrent-voltage behaviour. Apparently, the only restrictions to the use of relatively thick nanostructured electrodes are the penetration depth of the incident light, the rate of diffusion/migration of the electro active species within the electrode and the conductivity of the electrolyte. (authors)

  13. Mobile Intelligent Autonomous Systems

    Directory of Open Access Journals (Sweden)

    Jitendra R. Raol

    2010-01-01

    Full Text Available Mobile intelligent autonomous systems (MIAS is a fast emerging research area. Although it can be regarded as a general R&D area, it is mainly directed towards robotics. Several important subtopics within MIAS research are:(i perception and reasoning, (ii mobility and navigation,(iii haptics and teleoperation, (iv image fusion/computervision, (v modelling of manipulators, (vi hardware/software architectures for planning and behaviour learning leadingto robotic architecture, (vii vehicle-robot path and motionplanning/control, (viii human-machine interfaces for interaction between humans and robots, and (ix application of artificial neural networks (ANNs, fuzzy logic/systems (FLS,probabilistic/approximate reasoning (PAR, Bayesian networks(BN and genetic algorithms (GA to the above-mentioned problems. Also, multi-sensor data fusion (MSDF playsvery crucial role at many levels of the data fusion process:(i kinematic fusion (position/bearing tracking, (ii imagefusion (for scene recognition, (iii information fusion (forbuilding world models, and (iv decision fusion (for tracking,control actions. The MIAS as a technology is useful for automation of complex tasks, surveillance in a hazardousand hostile environment, human-assistance in very difficultmanual works, medical robotics, hospital systems, autodiagnosticsystems, and many other related civil and military systems. Also, other important research areas for MIAScomprise sensor/actuator modelling, failure management/reconfiguration, scene understanding, knowledge representation, learning and decision-making. Examples ofdynamic systems considered within the MIAS would be:autonomous systems (unmanned ground vehicles, unmannedaerial vehicles, micro/mini air vehicles, and autonomousunder water vehicles, mobile/fixed robotic systems, dexterousmanipulator robots, mining robots, surveillance systems,and networked/multi-robot systems, to name a few.Defence Science Journal, 2010, 60(1, pp.3-4,

  14. Gold nanoparticles embedded in Ta 2 O 5 /Ta 3 N 5 as active visible-light plasmonic photocatalysts for solar hydrogen evolution

    KAUST Repository

    Luo, Yujing

    2014-07-10

    Here, we demonstrate a new recreating photocatalytic activity of a Nano Au/Ta2O5 composite for hydrogen evolution from water as a visible-light-responsive plasmonic photocatalyst by embedding Au nanoparticles in a Ta2O5 host lattice. The Nano Au/Ta2O 5 composite samples were prepared through a simple Pechini-type sol-gel process. Further nitridating Nano Au/Ta2O5 composite samples in ammonia flow at 1123 K yielded Nano Au/Ta3N 5 composite samples. The obtained Nano Au/Ta3N5 composite exhibited a significantly enhanced photocatalytic activity in the visible region for hydrogen evolution from water compared with blank Ta 3N5 nanoparticles. UV-visible diffuse reflectance spectra and photocatalytic activity measurements indicated that the excitation of surface plasmon resonance of Au nanoparticles is responsible for the new recreating photocatalytic activity of the Nano Au/Ta2O5 composite and significantly enhanced photocatalytic activity of the Nano Au/Ta3N5 composite for hydrogen evolution in the visible region, which might be ascribed to the charge transfer effect in Nano Au/Ta 2O5 composite and the synergetic effect of charge transfer and near-field electromagnetic effect in Nano Au/Ta3N5 composite induced by surface plasmon resonance of embedded Au nanoparticles. The current study could provide a new paradigm for designing plasmonic metal/semiconductor composite systems for photocatalytic, photovoltaic and other optoelectronic devices. © the Partner Organisations 2014.

  15. Numerical Simulation of Mixed Convection in Solar Cavity Receiver for Hydrogen Production%太阳能制氢腔式吸热器混合对流的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    肖鹏; 郭烈锦; 吕友军

    2012-01-01

    Mixed convection heat loss is the key factor to determine the thermal efficiency of solar cavity receiver for hydrogen production by biomass gasification using concentrated solar energy. In this paper, the solar cavity receiver, built by State Key Laboratory of Multiphase Flow in Power Engineering, was numerically modeled to study the characteristics of mixed convection heat loss. The RNG k - ε turbulence model was adopted to investigate the flow pattern and mixed convection heat transfer characteristics around the solar cavity with external wind effect. The correlation for Nusselt number was obtained with various wind directions and wind velocity. The result showed that, the side towards wind and semi-side towards wind have the most significant effects on convection heat loss. When the wind velocity was big enough to make Richardson greater than 1, the forced convection drive by external wind is dominated, and mixed convection heat loss increases with augmentation of Re and the increase of wind velocity.%混合对流热损失是影响太阳能与生物质超临界水气化耦合制氢腔式吸热器热效率的关键因素之一。本文以动力工程多相流实验室建成的生物质超临界水与太阳能聚集供热耦合制氢腔式吸热器为研究对象,对腔式吸热器混合对流换热进行了数值模拟研究。通过使用RNG惫一£湍流模型,研究了制氢吸热器在外界风吹掠环境下的混合对流热损失,获得了腔式吸热器在不同风速、风向吹掠下的混合对流换热准则Nusselt数。模拟结果表明,侧向风与侧迎向风对腔内对流热损失影响最大,当风速超过某一数值(Richardson数〉1),外界风诱发的强制对流会在对流热损失中占主导作用,且随着风速增加,混合对流热损失随Re提高而增大。

  16. Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results on the response to the geomagnetic and solar wind activity conditions

    CERN Document Server

    Kronberg, Elena A; Daly, Patrick W; Grigorenko, Elena E; Kistler, Lynn; Fränz, Markus; Dandouras, Iannis

    2012-01-01

    The composition of ions plays a crucial role for the fundamental plasma properties in the terrestrial magnetosphere. We investigate the oxygen-to-hydrogen ratio in the near-Earth magnetosphere from -10 RE274 keV O+ ion intensities, relative to the corresponding hydrogen intensities; (3) In contrast to ~10 keV ions, the >274 keV O+ ions show the strongest acceleration during growth phase and not during the expansion phase itself. This suggests a connection between the energy input to the magnetosphere and the effective energization of energetic ions during growth phase; (4) The ratio between quiet and disturbed times for the intensities of ion ionospheric outflow is similar to those observed in the near-Earth magnetosphere at >274 keV. Therefore, the increase of the energetic ion intensity during disturbed time is more likely due to the intensification than to the more effective acceleration of the ionospheric source. In conclusion, the energization process in the near-Earth magnetosphere is mass dependent and...

  17. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  18. Autonomous software: Myth or magic?

    CERN Document Server

    Allan, Alasdair; Saunders, Eric S

    2008-01-01

    We discuss work by the eSTAR project which demonstrates a fully closed loop autonomous system for the follow up of possible micro-lensing anomalies. Not only are the initial micro-lensing detections followed up in real time, but ongoing events are prioritised and continually monitored, with the returned data being analysed automatically. If the ``smart software'' running the observing campaign detects a planet-like anomaly, further follow-up will be scheduled autonomously and other telescopes and telescope networks alerted to the possible planetary detection. We further discuss the implications of this, and how such projects can be used to build more general autonomous observing and control systems.

  19. Cybersecurity for aerospace autonomous systems

    Science.gov (United States)

    Straub, Jeremy

    2015-05-01

    High profile breaches have occurred across numerous information systems. One area where attacks are particularly problematic is autonomous control systems. This paper considers the aerospace information system, focusing on elements that interact with autonomous control systems (e.g., onboard UAVs). It discusses the trust placed in the autonomous systems and supporting systems (e.g., navigational aids) and how this trust can be validated. Approaches to remotely detect the UAV compromise, without relying on the onboard software (on a potentially compromised system) as part of the process are discussed. How different levels of autonomy (task-based, goal-based, mission-based) impact this remote characterization is considered.

  20. Hydrogen Spectrum

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    The series of absorption or emission lines that are characteristic of the hydrogen atom. According to the Bohr theory of the hydrogen atom, devised by Danish physicist Neils Bohr (1885-1962) in 1913, the hydrogen atom can be envisaged as consisting of a central nucleus (a proton) around which a single electron revolves. The electron is located in one of a number of possible permitted orbits, each...

  1. Photoelectrochemical hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Rocheleau, R.E.; Miller, E.; Zhang, Z. [Univ. of Hawaii, Honolulu, HI (United States)

    1995-09-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. Photoelectrochemical devices-direct photoconversion systems utilizing a photovoltaic-type structure coated with water-splitting catalysts-represent a promising option to meet this goal. Direct solar-to-chemical conversion efficiencies greater than 7% and photoelectrode lifetimes of up to 30 hours in 1 molar KOH have been demonstrated in our laboratory using low-cost, amorphous-silicon-based photoelectrodes. Loss analysis models indicate that the DOE`s goal of 10% solar-to-chemical conversion can be met with amorphous-silicon-based structures optimized for hydrogen production. In this report, we describe recent progress in the development of thin-film catalytic/protective coatings, improvements in photoelectrode efficiency and stability, and designs for higher efficiency and greater stability.

  2. Hydrogen Storage and Production Project

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Abhijit [Univ. of Arkansas, Little Rock, AR (United States); Biris, A. S. [Univ. of Arkansas, Little Rock, AR (United States); Mazumder, M. K. [Univ. of Arkansas, Little Rock, AR (United States); Karabacak, T. [Univ. of Arkansas, Little Rock, AR (United States); Kannarpady, Ganesh [Univ. of Arkansas, Little Rock, AR (United States); Sharma, R. [Univ. of Arkansas, Little Rock, AR (United States)

    2011-07-31

    This is the final technical report. This report is a summary of the project. The goal of our project is to improve solar-to-hydrogen generation efficiency of the PhotoElectroChemical (PEC) conversion process by developing photoanodes with high absorption efficiency in the visible region of the solar radiation spectrum and to increase photo-corrosion resistance of the electrode for generating hydrogen from water. To meet this goal, we synthesized nanostructured heterogeneous semiconducting photoanodes with a higher light absorption efficiency compared to that of TiO2 and used a corrosion protective layer of TiO2. While the advantages of photoelectrochemical (PEC) production of hydrogen have not yet been realized, the recent developments show emergence of new nanostructural designs of photoanodes and choices of materials with significant gains in photoconversion efficiency.

  3. SIRTF autonomous star tracker

    Science.gov (United States)

    van Bezooijen, Roelof W. H.

    2003-03-01

    Two redundant AST-301 autonomous star trackers (AST) serve as the primary attitude sensors for JPL's space infrared telescope facility (SIRTF). These units, which employ a 1553B interface to output their attitude quaternions and uncertainty at a 2 Hz rate, provide a 1 σaccuracy of better than 0.18, 0.18, and 5.1 arcsec about their X, Y, and Z axes, respectively. This is a factor 5.5 better than the accuracy of the flight-proven AST-201 from which the trackers were derived. To obtain this improvement, the field of view (FOV) was reduced to 5 by 5 degrees, the accurate Tycho-1 and ACT catalogs were used for selecting the 71,830 guide stars, star image centroiding was improved to better than 1/50th of a pixel, and optimal attitude estimation was implemented. In addition, the apparent direction to each guide star in the FOV is compensated for proper motion, parallax, velocity aberration, and optical distortion. The AST-301 employs autonomous time-delayed integration (TDI) to achieve image motion compensation (IMC) about its X axis that prevents accuracy degradation, even at rates of 2.1 deg/s, making it actually suitable for use on spinning spacecraft. About the Y axis, a software function called "image motion accommodation" (IMA) processes smeared images to maximize the signal to noise ratio of the resulting synthetic images, which enables robust and accurate tracking at rates tested up to 0.42 deg/s. The AST-301 is capable of acquiring its attitude anywhere in the sky in less than 3 seconds with a 99.98% probability of success, without requiring any a priori attitude knowledge. Following a description of the 7.1 kg AST-301, its operation and IMA, the methodology for translating the night sky test data into performance numbers is presented, while, in addition, the results of tests used to measure alignment stability over temperature are included.

  4. Aging dependent phase transformation of mesostructured titanium dioxide nanomaterials prepared by evaporation-induced self-assembly process: Implications for solar hydrogen production

    Directory of Open Access Journals (Sweden)

    Luther Mahoney

    2015-08-01

    Full Text Available Mesostructured titanium dioxide materials were prepared by Evaporation-Induced Self-Assembly (EISA method using titanium isopropoxide and a cationic surfactant. The titania phase could be tuned by simply varying the aging time. As the aging time increased, hierarchically structured mesoporous materials with mixed phases of titania were obtained. The rutile content was found to generally increase with length in aging time. The mesostructured materials were evaluated for hydrogen production, and a mixed phase consisting of 95% anatase and 5% rutile showed the highest activity. This study indicates that the aging time is an important parameter for the preparation of mesostructured materials with hierarchical porosities and mixed phase(s of titania.

  5. Framework for Autonomous Optimization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phoenix Integration and MIT propose to create a novel autonomous optimization tool and application programming interface (API). The API will demonstrate the ability...

  6. Cranial Autonomic Symptoms in Migraine

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2009-11-01

    Full Text Available Cranial autonomic symptoms (CAS in patients with migraine and cluster headaches (CH were characterized and compared in a prospective study of consecutive patients attending a headache clinic at Taipei Veterans General Hospital, Taiwan.

  7. Design of Autonomous Gel Actuators

    Directory of Open Access Journals (Sweden)

    Shuji Hashimoto

    2011-01-01

    Full Text Available In this paper, we introduce autonomous gel actuators driven by chemical energy. The polymer gels prepared here have cyclic chemical reaction networks. With a cyclic reaction, the polymer gels generate periodical motion. The periodic motion of the gel is produced by the chemical energy of the oscillatory Belouzov-Zhabotinsky (BZ reaction. We have succeeded in making synthetic polymer gel move autonomously like a living organism. This experimental fact represents the great possibility of the chemical robot.

  8. Is paramecium swimming autonomic?

    Science.gov (United States)

    Bandyopadhyay, Promode R.; Toplosky, Norman; Hansen, Joshua

    2010-11-01

    We seek to explore if the swimming of paramecium has an underlying autonomic mechanism. Such robotic elements may be useful in capturing the disturbance field in an environment in real time. Experimental evidence is emerging that motion control neurons of other animals may be present in paramecium as well. The limit cycle determined using analog simulation of the coupled nonlinear oscillators of olivo-cerebellar dynamics (ieee joe 33, 563-578, 2008) agrees with the tracks of the cilium of a biological paramecium. A 4-motor apparatus has been built that reproduces the kinematics of the cilium motion. The motion of the biological cilium has been analyzed and compared with the results of the finite element modeling of forces on a cilium. The modeling equates applied torque at the base of the cilium with drag, the cilium stiffness being phase dependent. A low friction pendulum apparatus with a multiplicity of electromagnetic actuators is being built for verifying the maps of the attractor basin computed using the olivo-cerebellar dynamics for different initial conditions. Sponsored by ONR 33.

  9. AUTONOMOUS GAUSSIAN DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Heiles, Carl [Radio Astronomy Lab, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Hennebelle, Patrick [Laboratoire AIM, Paris-Saclay, CEA/IRFU/SAp-CNRS-Université Paris Diderot, F-91191 Gif-sur Yvette Cedex (France); Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville, Socorro, NM 87801 (United States); Dickey, John, E-mail: rlindner@astro.wisc.edu [University of Tasmania, School of Maths and Physics, Private Bag 37, Hobart, TAS 7001 (Australia)

    2015-04-15

    We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.

  10. [Autonomic peripheral neuropathy].

    Science.gov (United States)

    Adams, David; Cauquil, Cecile; Lozeron, Pierre

    2012-11-01

    The mechanisms of dysautonomic disturbances are varied and mostly acquired. They can result from lesions of sympathetic or parasympathetic vegetative fibers located in the peripheral contingent, or in the somatic contingent by demyelination or axonal loss; or more rarely by cellular bodies in the sympathetic or parasympathetic ganglia. Several chronic peripheral neuropathies can be associated with dysautonomia. Only some causes need to be known because they can be clinically significant. Dysautonomia may be seen during chronic acquired neuropathies but also acute or subacute ones. The most frequent cause in the world is the dysautonomia of the diabetes; it affects all the systems; the cardiovascular dysfunction has an impact on the prognosis for survival when it is severe. Hereditary autonomic neuropathies are rare; they can declare themselves very early during the Riley-Day syndrome or very late during amyloid polyneuropathies due to transthyretin gene mutation. The diagnosis can be confirmed by molecular biology. The dysautonomia is frequent and often severe. These neuropathies justify symptomatic treatment to improve quality of life. For some of them, a specific treatment can be proposed to treat the causal affection to try to stop the progression of the disease.

  11. Heterojunction of Zinc Blende/Wurtzite in Zn1-xCdxS Solid Solution for Efficient Solar Hydrogen Generation: X-ray Absorption/Diffraction Approaches.

    Science.gov (United States)

    Hsu, Ying-Ya; Suen, Nian-Tzu; Chang, Chung-Chieh; Hung, Sung-Fu; Chen, Chi-Liang; Chan, Ting-Shan; Dong, Chung-Li; Chan, Chih-Chieh; Chen, San-Yuan; Chen, Hao Ming

    2015-10-14

    In the past decade, inorganic semiconductors have been successfully demonstrated as light absorbers in efficient solar water splitting to generate chemical fuels. Pseudobinary semiconductors Zn1-xCdxS (0≤x≤1) have exhibited a superior photocatalytic reactivity of H2 production from splitting of water by artificial solar irradiation without any metal catalysts. However, most studies had revealed that the extremely high efficiency with an optimal content of Zn1-xCdxS solid solution was determined as a result of elevating the conduction band minimum (CBM) and the width of bandgap. In addition to corresponding band structure and bandgap, the local crystal structure should be taken into account as well to determine its photocatalytic performance. Herein, we demonstrated the correlations between the photocatalytic activity and structural properties that were first studied through synchrotron X-ray diffraction and X-ray absorption spectroscopy. The crystal structure transformed from zinc blende to coexisted phases of major zinc blende and minor wurtzite phases at a critical point. The heterojunction formed by coexistence of zinc blende and wurtzite phases in the Zn1-xCdxS solid solution can significantly improve the separation and migration of photoinduced electron-hole pairs. Besides, X-ray absorption spectra and UV-vis spectra revealed that the bandgap of the Zn0.45Cd0.55S sample extended into the region of visible light because of the incorporation of Cd element in the sample. These results provided a significant progress toward the realization of the photoelectrochemical mechanism in heterojunction between zinc blende and wurtzite phases, which can effectively separate the charge-carriers and further suppress their recombination to enhance the photocatalytic reactivity.

  12. Hydrogen Bibliography

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-01

    The Hydrogen Bibliography is a compilation of research reports that are the result of research funded over the last fifteen years. In addition, other documents have been added. All cited reports are contained in the National Renewable Energy Laboratory (NREL) Hydrogen Program Library.

  13. Applications of the use of the renewable energies, solar power and wind power, for the securing of hydrogen, as power supply of the fuel cells; Obtencion de hidrogeno, a partir de la electrolisis del agua mediante energias renovables almacenamiento y aplicaciones

    Energy Technology Data Exchange (ETDEWEB)

    San Martin, J. J.; Martin, I.; Aperribay, V.; San Martin, J. I.; Arrieta, J. M.; Zuazua, J.; Romero, E.

    2004-07-01

    The object of the presented communication is to show the applications of the use of the renewable energies, particularly the solar power and the wind power, for the securing of hydrogen, as power supply of the fuel cells. The electrical energy produced in the solar badges and in the windpowers is, principally, injected into the electrical networks, for his transport, distribution and consumption, if the network the demand. The novel aspect is, that if the network does not demand potency, this one is transformed into hydrogen at the same photovoltaic station or into the base of the tower of the windpower and, later, stored to feed the fuel cells, not producing to him any type of element pollutant, since the residual element is the water. (Author)

  14. Hydrogen and OUr Energy Future

    Energy Technology Data Exchange (ETDEWEB)

    Rick Tidball; Stu Knoke

    2009-03-01

    In 2003, President George W. Bush announced the Hydrogen Fuel Initiative to accelerate the research and development of hydrogen, fuel cell, and infrastructure technologies that would enable hydrogen fuel cell vehicles to reach the commercial market in the 2020 timeframe. The widespread use of hydrogen can reduce our dependence on imported oil and benefit the environment by reducing greenhouse gas emissions and criteria pollutant emissions that affect our air quality. The Energy Policy Act of 2005, passed by Congress and signed into law by President Bush on August 8, 2005, reinforces Federal government support for hydrogen and fuel cell technologies. Title VIII, also called the 'Spark M. Matsunaga Hydrogen Act of 2005' authorizes more than $3.2 billion for hydrogen and fuel cell activities intended to enable the commercial introduction of hydrogen fuel cell vehicles by 2020, consistent with the Hydrogen Fuel Initiative. Numerous other titles in the Act call for related tax and market incentives, new studies, collaboration with alternative fuels and renewable energy programs, and broadened demonstrations--clearly demonstrating the strong support among members of Congress for the development and use of hydrogen fuel cell technologies. In 2006, the President announced the Advanced Energy Initiative (AEI) to accelerate research on technologies with the potential to reduce near-term oil use in the transportation sector--batteries for hybrid vehicles and cellulosic ethanol--and advance activities under the Hydrogen Fuel Initiative. The AEI also supports research to reduce the cost of electricity production technologies in the stationary sector such as clean coal, nuclear energy, solar photovoltaics, and wind energy.

  15. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  16. Hydrogen carriers

    Science.gov (United States)

    He, Teng; Pachfule, Pradip; Wu, Hui; Xu, Qiang; Chen, Ping

    2016-12-01

    Hydrogen has the potential to be a major energy vector in a renewable and sustainable future energy mix. The efficient production, storage and delivery of hydrogen are key technical issues that require improvement before its potential can be realized. In this Review, we focus on recent advances in materials development for on-board hydrogen storage. We highlight the strategic design and optimization of hydrides of light-weight elements (for example, boron, nitrogen and carbon) and physisorbents (for example, metal-organic and covalent organic frameworks). Furthermore, hydrogen carriers (for example, NH3, CH3OH-H2O and cycloalkanes) for large-scale distribution and for on-site hydrogen generation are discussed with an emphasis on dehydrogenation catalysts.

  17. Solar Fuel Generator

    Science.gov (United States)

    Lewis, Nathan S. (Inventor); West, William C. (Inventor)

    2017-01-01

    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  18. Solar fuel generator

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nathan S.; West, William C.

    2017-01-17

    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  19. Hydrogen fuel - Universal energy

    Science.gov (United States)

    Prince, A. G.; Burg, J. A.

    The technology for the production, storage, transmission, and consumption of hydrogen as a fuel is surveyed, with the physical and chemical properties of hydrogen examined as they affect its use as a fuel. Sources of hydrogen production are described including synthesis from coal or natural gas, biomass conversion, thermochemical decomposition of water, and electrolysis of water, of these only electrolysis is considered economicially and technologically feasible in the near future. Methods of production of the large quantities of electricity required for the electrolysis of sea water are explored: fossil fuels, hydroelectric plants, nuclear fission, solar energy, wind power, geothermal energy, tidal power, wave motion, electrochemical concentration cells, and finally ocean thermal energy conversion (OTEC). The wind power and OTEC are considered in detail as the most feasible approaches. Techniques for transmission (by railcar or pipeline), storage (as liquid in underwater or underground tanks, as granular metal hydride, or as cryogenic liquid), and consumption (in fuel cells in conventional power plants, for home usage, for industrial furnaces, and for cars and aircraft) are analyzed. The safety problems of hydrogen as a universal fuel are discussed, noting that they are no greater than those for conventional fuels.

  20. Solar Imagery - Composites - Synoptic Maps - McIntosh

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 1964 (solar cycle 20) Patrick McIntosh began creating hand-drawn synoptic maps of solar activity, based on Hydrogen alpha (H?) imaging measurements. These...

  1. Solar Indices - Solar Corona

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  2. Solar Indices - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  3. Solar Indices - Solar Irradiance

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  4. Solar Indices - Solar Ultraviolet

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  5. Solar-driven hydrogen evolution using a CuInS2/CdS/ZnO heterostructure nanowire array as an efficient photoanode

    Science.gov (United States)

    Choi, Youngwoo; Beak, Minki; Yong, Kijung

    2014-07-01

    Photoanodes prepared using CuInS2/CdS/ZnO nanowires were fabricated by a solution-based process for constructing a photo-driven hydrogen generation system. For efficient light harvesting and photoexcited charge collection, ZnO nanowire (NW) photoanode arrays were co-sensitized with CdS and CuInS2 (CIS). A CdS layer was deposited on the ZnO NW via successive ion layer adsorption and reaction (SILAR), and the CIS layer was prepared by depositing a molecular precursor solution onto the CdS/ZnO NW. The generated anodic photocurrent was increased with the subsequent deposition of the CIS and CdS layers. Ultraviolet photoelectron spectroscopy analysis revealed cascade type-II band alignments for the CIS/CdS/ZnO NW photoanodes, which enabled efficient electron collection. Our heterostructure photoelectrode has generated a greatly improved photocurrent density of 13.8 mA cm-2 at 0.3 V vs. SCE under 1 sun illumination.

  6. Unusual Structural Autonomic Disorders Presenting in Pediatrics: Disorders Associated with Hypoventilation and Autonomic Neuropathies.

    Science.gov (United States)

    Chelimsky, Gisela; Chelimsky, Thomas

    2017-02-01

    Structural autonomic disorders (producing structural damage to the autonomic nervous system or autonomic centers) are far less common than functional autonomic disorders (reflected in abnormal function of a fundamentally normal autonomic nervous system) in children and teenagers. This article focuses on this uncommon first group in the pediatric clinic. These disorders are grouped into 2 main categories: those characterized by hypoventilation and those that feature an autonomic neuropathy. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. 多碟太阳能聚热与生物质超临界水气化耦合制氢%HYDROGEN PRODUCTION COUPLING SYSTEM OF MULTI-DISHES CONCENTRATING SOLAR THERMAL AND BIOMASS GASIFICATION IN SUPERCRITICAL WATER

    Institute of Scientific and Technical Information of China (English)

    廖波; 郭烈锦; 吕友军; 张西民

    2011-01-01

    A continuous hydrogen production coupling system of multi-dishes concentrating solar thermal and biomass gasification in supercritical water (SCW) has been designed and constructed. Preliminary gasification experiments on biomass model compounds (ethylene glycol,glycerol, glucose) has been operated in the apparatus. Effects of direct normal solar irradiation (DNI), feedstock composition, feedstock concentration, residence time on gasification were studied.The results showed that DNI has prominent effect on the temperature of reactor wall and absorption cavity, thereby gasification results were affected. The outlet fluid temperature reached 520-676℃ when the DNI was 363-656W/m2, so the need of the energy and temperature for biomass gasification in supercritical water were met. As to 0.1 mol/L glucose gasification, the average volume percentage of H2 is more than 50%, average H2 yield reached 27.2mol/kg, and the maximal gasification rate nearly 110% were reached. The feedstock with low biomass content and long residence time was easier to gasify. Experimental results validated that using solar energy as heat source to drive biomass gasification in supercritical water for hydrogen production is entirely feasible.%搭建了一套连续式多碟太阳能聚热与生物质超临界水气化耦合制氢系统,以生物质模型化合物(乙二醇、丙三醇、葡萄糖)为原料在该装置上进行了气化制氢实验,研究了太阳能直接辐照度(DNI)、物料成分、物料浓度、停留时间对气化效果的影响.实验结果表明:太阳能直接辐照度对太阳能吸收器腔内及反应器壁温的影响较大,进而能影响气化效果,在实验流量、压力范围内当DNI为363~656W/m2时,反应器出口流体温度达520~676℃,可以满足生物质超临界水气化制氢的温度及能量需要.0.1mol/L葡萄糖气化H2体积分数均值超过50%,H2产量为27.2mol/kg,气化率达109.7%.低物料浓度和长停留时间有利于气化

  8. Integrated Motion Planning and Autonomous Control Technology for Autonomous ISR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI and MIT propose to design, implement and test a comprehensive Integrated Mission Planning & Autonomous Control Technology (IMPACT) for Autonomous ISR...

  9. Autonomous Landing on Moving Platforms

    KAUST Repository

    Mendoza Chavez, Gilberto

    2016-08-01

    This thesis investigates autonomous landing of a micro air vehicle (MAV) on a nonstationary ground platform. Unmanned aerial vehicles (UAVs) and micro air vehicles (MAVs) are becoming every day more ubiquitous. Nonetheless, many applications still require specialized human pilots or supervisors. Current research is focusing on augmenting the scope of tasks that these vehicles are able to accomplish autonomously. Precise autonomous landing on moving platforms is essential for self-deployment and recovery of MAVs, but it remains a challenging task for both autonomous and piloted vehicles. Model Predictive Control (MPC) is a widely used and effective scheme to control constrained systems. One of its variants, output-feedback tube-based MPC, ensures robust stability for systems with bounded disturbances under system state reconstruction. This thesis proposes a MAV control strategy based on this variant of MPC to perform rapid and precise autonomous landing on moving targets whose nominal (uncommitted) trajectory and velocity are slowly varying. The proposed approach is demonstrated on an experimental setup.

  10. Research and development of Ro-boat: an autonomous river cleaning robot

    Science.gov (United States)

    Sinha, Aakash; Bhardwaj, Prashant; Vaibhav, Bipul; Mohommad, Noor

    2013-12-01

    Ro-Boat is an autonomous river cleaning intelligent robot incorporating mechanical design and computer vision algorithm to achieve autonomous river cleaning and provide a sustainable environment. Ro-boat is designed in a modular fashion with design details such as mechanical structural design, hydrodynamic design and vibrational analysis. It is incorporated with a stable mechanical system with air and water propulsion, robotic arms and solar energy source and it is proceed to become autonomous by using computer vision. Both "HSV Color Space" and "SURF" are proposed to use for measurements in Kalman Filter resulting in extremely robust pollutant tracking. The system has been tested with successful results in the Yamuna River in New Delhi. We foresee that a system of Ro-boats working autonomously 24x7 can clean a major river in a city on about six months time, which is unmatched by alternative methods of river cleaning.

  11. Technical Analysis of Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Ali T-Raissi

    2005-01-14

    The aim of this work was to assess issues of cost, and performance associated with the production and storage of hydrogen via following three feedstocks: sub-quality natural gas (SQNG), ammonia (NH{sub 3}), and water. Three technology areas were considered: (1) Hydrogen production utilizing SQNG resources, (2) Hydrogen storage in ammonia and amine-borane complexes for fuel cell applications, and (3) Hydrogen from solar thermochemical cycles for splitting water. This report summarizes our findings with the following objectives: Technoeconomic analysis of the feasibility of the technology areas 1-3; Evaluation of the hydrogen production cost by technology areas 1; and Feasibility of ammonia and/or amine-borane complexes (technology areas 2) as a means of hydrogen storage on-board fuel cell powered vehicles. For each technology area, we reviewed the open literature with respect to the following criteria: process efficiency, cost, safety, and ease of implementation and impact of the latest materials innovations, if any. We employed various process analysis platforms including FactSage chemical equilibrium software and Aspen Technologies AspenPlus and HYSYS chemical process simulation programs for determining the performance of the prospective hydrogen production processes.

  12. Autonomous mobile robots: Vehicles with cognitive control

    Energy Technology Data Exchange (ETDEWEB)

    Meystel, A.

    1987-01-01

    This book explores a new rapidly developing area of robotics. It describes the state-of-the-art intelligence control, applied machine intelligence, and research and initial stages of manufacturing of autonomous mobile robots. A complete account of the theoretical and experimental results obtained during the last two decades together with some generalizations on Autonomous Mobile Systems are included in this book. Contents: Introduction; Requirements and Specifications; State-of-the-art in Autonomous Mobile Robots Area; Structure of Intelligent Mobile Autonomous System; Planner, Navigator; Pilot; Cartographer; Actuation Control; Computer Simulation of Autonomous Operation; Testing the Autonomous Mobile Robot; Conclusions; Bibliography.

  13. 基于 GPS 的太阳能平移式喷灌机自主导航系统设计与试验%Design and experiment of autonomous navigation system for solar powered linear move sprinkler machine based on GPS

    Institute of Scientific and Technical Information of China (English)

    刘柯楠; 吴普特; 朱德兰; 陈军; 郭浩

    2016-01-01

    achieve the autonomous navigation control of the solar-powered linear move sprinkler machine in the whole system. The path tracking experiments were operated and completed in Institute of Water Saving Agriculture in Arid Areas of China, Northwest A&F University (34°17′50′′N, 108°04′6′′E) in which the platform of the solar-powered linear move sprinkler machine based on GPS navigation was the research object on April 21, 2015. During the experiments, the running track of the solar-powered linear move sprinkler machine was recorded by a drop of water, and the walking deviation of a walking path and a predetermined path were measured every 30 cm. The results of path tracking experiments showed that the solar-powered linear move sprinkler machine automatic navigation control system could basically meet the irrigation requirements, and realized route trace well. In the process of a 30 m straight line tracking, the maximum lateral deviation was 17.3 cm and 18.4 cm at the speed of 0.4 and 0.8 m/min, showing a high reliability and stability. At last, the research above not only provides important information on the realization of the combination of agricultural machinery and solar energy technology, but also was the basis for the development of similar self-walking sprinkler irrigation machine.

  14. A hydrogen energy carrier. Volume 1: Summary. [for meeting energy requirements

    Science.gov (United States)

    Savage, R. L. (Editor); Blank, L. (Editor); Cady, T. (Editor); Cox, K. E. (Editor); Murray, R. (Editor); Williams, R. D. (Editor)

    1973-01-01

    The production, technology, transportation, and implementation of hydrogen into the energy system are discussed along with the fossil fuel cycle, hydrogen fuel cycle, and the demands for energy. The cost of hydrogen production by coal gasification; electrolysis by nuclear energy, and solar energy are presented. The legal aspects of a hydrogen economy are also discussed.

  15. Using amorphous silicon solar cells to boost the viability of luminescent solar concentrators

    NARCIS (Netherlands)

    Farrell, D.J.; van Sark, W.G.J.H.M.; Velthuijsen, S.; Schropp, R.E.I.

    2010-01-01

    We have, for the first time, designed and fabricated hydrogenated amorphous silicon solar cells to be used in conjunction with Luminescent Solar Concentrators (LSCs). LSCs are planar plastic sheets doped with organic dyes that absorb solar illumination and down shift the energy to narrowband

  16. Autonomous hazard detection and avoidance

    Science.gov (United States)

    Pien, Homer

    1992-01-01

    During GFY 91, Draper Laboratory was awarded a task by NASA-JSC under contract number NAS9-18426 to study and evaluate the potential for achieving safe autonomous landings on Mars using an on-board autonomous hazard detection and avoidance (AHDA) system. This report describes the results of that study. The AHDA task had four objectives: to demonstrate, via a closed-loop simulation, the ability to autonomously select safe landing sites and the ability to maneuver to the selected site; to identify key issues in the development of AHDA systems; to produce strawman designs for AHDA sensors and algorithms; and to perform initial trade studies leading to better understanding of the effect of sensor/terrain/viewing parameters on AHDA algorithm performance. This report summarizes the progress made during the first year, with primary emphasis on describing the tools developed for simulating a closed-loop AHDA landing. Some cursory performance evaluation results are also presented.

  17. Autonomous underwater riser inspection tool

    Energy Technology Data Exchange (ETDEWEB)

    Camerini, Claudio; Marnet, Robson [Petrobras SA, (Brazil); Freitas, Miguel; Von der Weid, Jean Pierre [CPTI/PUC-Rio, Rio de Janeiro, (Brazil); Artigas Lander, Ricardo [EngeMOVI, Curitiba, (Brazil)

    2010-07-01

    The detection of damage on the riser is a serious concern for pipeline companies. Visual examinations by remotely operated vehicle (ROV) are presently carried out to detect the defects but this process has limitations and is expensive. This paper presents the development of a new tool to ensure autonomous underwater riser inspection (AURI) that uses the riser itself for guidance. The AURI, which is autonomous in terms of control and power supply, is equipped with several cameras that perform a complete visual inspection of the riser with 100 % coverage of the external surface of the riser. The paper presents the detailed characteristics of the first AURI prototype, describes its launching procedure and provides the preliminary test results from pool testing. The results showed that the AURI is a viable system for autonomous riser inspection. Offshore tests on riser pipelines are scheduled to be performed shortly.

  18. Hereditary sensory and autonomic neuropathies.

    Science.gov (United States)

    Auer-Grumbach, Michaela

    2013-01-01

    Hereditary sensory and autonomic neuropathies (HSN/HSAN) are clinically and genetically heterogeneous disorders of the peripheral nervous system that predominantly affect the sensory and autonomic neurons. Hallmark features comprise not only prominent sensory signs and symptoms and ulcerative mutilations but also variable autonomic and motor disturbances. Autosomal dominant and autosomal recessive inheritance has been reported. Molecular genetics studies have identified disease-causing mutations in 11 genes. Some of the affected proteins have nerve-specific roles but underlying mechanisms have also been shown to involve sphingolipid metabolism, vesicular transport, structural integrity, and transcription regulation. Genetic and functional studies have substantially improved the understanding of the pathogenesis of the HSN/HSAN and will help to find preventive and causative therapies in the future.

  19. Discerning non-autonomous dynamics

    Science.gov (United States)

    Clemson, Philip T.; Stefanovska, Aneta

    2014-09-01

    Structure and function go hand in hand. However, while a complex structure can be relatively safely broken down into the minutest parts, and technology is now delving into nanoscales, the function of complex systems requires a completely different approach. Here the complexity clearly arises from nonlinear interactions, which prevents us from obtaining a realistic description of a system by dissecting it into its structural component parts. At best, the result of such investigations does not substantially add to our understanding or at worst it can even be misleading. Not surprisingly, the dynamics of complex systems, facilitated by increasing computational efficiency, is now readily tackled in the case of measured time series. Moreover, time series can now be collected in practically every branch of science and in any structural scale-from protein dynamics in a living cell to data collected in astrophysics or even via social networks. In searching for deterministic patterns in such data we are limited by the fact that no complex system in the real world is autonomous. Hence, as an alternative to the stochastic approach that is predominantly applied to data from inherently non-autonomous complex systems, theory and methods specifically tailored to non-autonomous systems are needed. Indeed, in the last decade we have faced a huge advance in mathematical methods, including the introduction of pullback attractors, as well as time series methods that cope with the most important characteristic of non-autonomous systems-their time-dependent behaviour. Here we review current methods for the analysis of non-autonomous dynamics including those for extracting properties of interactions and the direction of couplings. We illustrate each method by applying it to three sets of systems typical for chaotic, stochastic and non-autonomous behaviour. For the chaotic class we select the Lorenz system, for the stochastic the noise-forced Duffing system and for the non-autonomous the

  20. Autonomic Regulation of Splanchnic Circulation

    Directory of Open Access Journals (Sweden)

    Kathleen A Fraser

    1991-01-01

    Full Text Available The role of the autonomic nervous system in circulatory regulation of the splanchnic organs (stomach, small intestine, colon, liver, pancreas and spleen is reviewed. In general, the sympathetic nervous system is primarily involved in vasoconstriction, while the parasympathetic contributes to vasodilation. Vasoconstriction in the splanchnic circulation appears to be mediated by alpha-2 receptors and vasodilation by activation of primary afferent nerves with subsequent release of vasodilatory peptides, or by stimulation of beta-adrenergic receptors. As well, an important function of the autonomic nervous system is to provide a mechanism by which splanchnic vascular reserve can be mobilized during stress to maintain overall cardiovascular homeostasis.