WorldWideScience

Sample records for surface sur co2

  1. Surface Condensation of CO2 onto Kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Schaef, Herbert T.; Glezakou, Vassiliki Alexandra; Owen, Antionette T.; Ramprasad, Sudhir; Martin, Paul F.; McGrail, B. Peter

    2014-02-11

    The fundamental adsorption behavior of gaseous and supercritical carbon dioxide (CO2) onto poorly crystalline kaolinite (KGa-2) at conditions relevant to geologic sequestration has been investigated using a quartz crystal microbalance (QCM) and density functional theory (DFT) methods. The QCM data indicated linear adsorption of CO2 (0-0.3 mmol CO2/g KGa-2) onto the kaolinite surface up through the gaseous state (0.186 g/cm3). However in the supercritical region, CO2 adsorption increases dramatically, reaching a peak (0.9-1.0 mmol CO2/g KGa-2) near 0.43 g/cm3, before declining rapidly to surface adsorption values equivalent or below gaseous CO2. This adsorption profile was not observed with He or N2. Comparative density functional studies of CO2 interactions with kaolinite surface models rule out CO2 intercalation and confirm that surface adsorption is favored up to approximately 0.35 g/cm3 of CO2, showing distorted T-shaped CO2-CO2 clustering, typical of supercritical CO2 aggregation over the surface as the density increases. Beyond this point, the adsorption energy gain for any additional CO2 becomes less than the CO2 interaction energy (~0.2 eV) in the supercritical medium resulting in overall desorption of CO2 from the kaolinite surface.

  2. Detection of CO2 leakage by the surface-soil CO2-concentration monitoring (SCM) system in a small scale CO2 release test

    Science.gov (United States)

    Chae, Gitak; Yu, Soonyoung; Sung, Ki-Sung; Choi, Byoung-Young; Park, Jinyoung; Han, Raehee; Kim, Jeong-Chan; Park, Kwon Gyu

    2015-04-01

    Monitoring of CO2 release through the ground surface is essential to testify the safety of CO2 storage projects. We conducted a feasibility study of the multi-channel surface-soil CO2-concentration monitoring (SCM) system as a soil CO2 monitoring tool with a small scale injection. In the system, chambers are attached onto the ground surface, and NDIR sensors installed in each chamber detect CO2 in soil gas released through the soil surface. Before injection, the background CO2 concentrations were measured. They showed the distinct diurnal variation, and were positively related with relative humidity, but negatively with temperature. The negative relation of CO2 measurements with temperature and the low CO2 concentrations during the day imply that CO2 depends on respiration. The daily variation of CO2 concentrations was damped with precipitation, which can be explained by dissolution of CO2 and gas release out of pores through the ground surface with recharge. For the injection test, 4.2 kg of CO2 was injected 1 m below the ground for about 30 minutes. In result, CO2 concentrations increased in all five chambers, which were located less than 2.5 m of distance from an injection point. The Chamber 1, which is closest to the injection point, showed the largest increase of CO2 concentrations; while Chamber 2, 3, and 4 showed the peak which is 2 times higher than the average of background CO2. The CO2 concentrations increased back after decreasing from the peak around 4 hours after the injection ended in Chamber 2, 4, and 5, which indicated that CO2 concentrations seem to be recovered to the background around 4 hours after the injection ended. To determine the leakage, the data in Chamber 2 and 5, which had low increase rates in the CO2 injection test, were used for statistical analysis. The result shows that the coefficient of variation (CV) of CO2 measurements for 30 minutes is efficient to determine a leakage signal, with reflecting the abnormal change in CO2

  3. CO2 hydrogenation on a metal hydride surface.

    Science.gov (United States)

    Kato, Shunsuke; Borgschulte, Andreas; Ferri, Davide; Bielmann, Michael; Crivello, Jean-Claude; Wiedenmann, Daniel; Parlinska-Wojtan, Magdalena; Rossbach, Peggy; Lu, Ye; Remhof, Arndt; Züttel, Andreas

    2012-04-28

    The catalytic hydrogenation of CO(2) at the surface of a metal hydride and the corresponding surface segregation were investigated. The surface processes on Mg(2)NiH(4) were analyzed by in situ X-ray photoelectron spectroscopy (XPS) combined with thermal desorption spectroscopy (TDS) and mass spectrometry (MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). CO(2) hydrogenation on the hydride surface during hydrogen desorption was analyzed by catalytic activity measurement with a flow reactor, a gas chromatograph (GC) and MS. We conclude that for the CO(2) methanation reaction, the dissociation of H(2) molecules at the surface is not the rate controlling step but the dissociative adsorption of CO(2) molecules on the hydride surface.

  4. Simulating CO2 adsorption and diffusion on a graphite surface

    NARCIS (Netherlands)

    Trinh, T.T.; Vlugt, T.J.H.; Hägg, M.B.; Bedeaux, D.; Kjelstrup, S.H.

    2013-01-01

    We performed classical molecular dynamics (MD) simulation to understand the mechanism of CO2 adsorption and transport on graphite surface. The temperature of the system in our simulation was in the range 300-500K. The simulation data show that there are two layers of CO2 molecules absorbed on the su

  5. A uniform, quality controlled Surface Ocean CO2 Atlas (SOCAT

    Directory of Open Access Journals (Sweden)

    T. Takahashi

    2012-08-01

    Full Text Available A well documented, publicly available, global data set of surface ocean carbon dioxide (CO2 parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC. Many additional CO2 data, not yet made public via the Carbon Dioxide Information Analysis Center (CDIAC, were retrieved from data originators, public websites and other data centres. All data were put in a uniform format following a strict protocol. Quality control was carried out according to clearly defined criteria. Regional specialists performed the quality control, using state-of-the-art web-based tools, specially developed for accomplishing this global team effort. SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data points from the global oceans and coastal seas, spanning four decades (1968–2007. Three types of data products are available: individual cruise files, a merged complete data set and gridded products. With the rapid expansion of marine CO2 data collection and the importance of quantifying net global oceanic CO2 uptake and its changes, sustained data synthesis and data access are priorities.

  6. A uniform, quality controlled Surface Ocean CO2 Atlas (SOCAT

    Directory of Open Access Journals (Sweden)

    B. Pfeil

    2013-04-01

    Full Text Available A well-documented, publicly available, global data set of surface ocean carbon dioxide (CO2 parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC. Many additional CO2 data, not yet made public via the Carbon Dioxide Information Analysis Center (CDIAC, were retrieved from data originators, public websites and other data centres. All data were put in a uniform format following a strict protocol. Quality control was carried out according to clearly defined criteria. Regional specialists performed the quality control, using state-of-the-art web-based tools, specially developed for accomplishing this global team effort. SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data points from the global oceans and coastal seas, spanning four decades (1968–2007. Three types of data products are available: individual cruise files, a merged complete data set and gridded products. With the rapid expansion of marine CO2 data collection and the importance of quantifying net global oceanic CO2 uptake and its changes, sustained data synthesis and data access are priorities.

  7. The Source Of CO2 Ice On Enceladus' Surface

    Science.gov (United States)

    Matson, D.; Davies, A.; Johnson, T. V.; Castillo-Rogez, J. C.; Lunine, J. I.

    2012-12-01

    Brown et al. (2006) identified CO2 ice on the surface of Enceladus within the South Polar Terrain using Cassini VIMS data. Considering the volatility of CO2, they suggested that the CO2 ice deposits resulted from an active replenishment process. Until now the nature of this process has been a mystery. Although there is a relatively small amount of CO2 in the water vapor erupted by the plumes, water-frost will dominate the spectra of the resulting deposits and the CO2 signature will be masked. We point out that CO2 frost deposits are a possible product of the water circulation model proposed by Matson et al. (2012). In this model, buoyant CO2-bubble-rich water rises up from the ocean and into fissures in the icy crust. When a neutral buoyancy level is reached, the water flows horizontally along the fissures under a relatively thin ice cap. Heat lost from the water beneath the ice supplies heat for the thermal anomalies identified on the surface. Even as the water is flowing horizontally, it continues to lose CO2 because bubbles continue to rise. Recesses and other irregularities on the bottom of the surface ice allow the bubble-gas to collect in pockets. When these are fissured by recurring tidal stresses (Hurford et al., 2007), the CO2 gas can escape and condense nearby on surfaces that are cold enough. The pure CO2 ice deposits discussed here are not to be confused with other deposits seen by VIMS in which the CO2 may be trapped in water-ice matrices. These have different spectral signatures and may be in the icy dust-sized grains ejected by the eruptive plumes. References: Brown et al. (2006) Science, 311, 5766; Matson et al. (2012) Icarus, in press, doi 0.1016/j.icarus.2012.05.031; Hurford et al. (2007) Nature 447, 292. This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA.

  8. Surface Ocean CO2 Atlas (SOCAT) gridded data products

    Energy Technology Data Exchange (ETDEWEB)

    Sabine, Christopher [NOAA Pacific Marine Environmental Laboratory; Hankin, S. [Pacific Northwest National Laboratory (PNNL); Koyuk, H [Joint Institute for the Study of the Atmosphere and Ocean, University of Washington; Bakker, D C E [School of Environmental Sciences, University of East Anglia, Norwich, UK; Pfeil, B [Geophysical Institute, University of Bergen; Uni Research AS, Bergen, Norway; Olsen, A [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Metzl, N [Universite Pierre et Marie Curie, LOCEAN/IPSL, Paris, France; Kozyr, Alexander [ORNL; Fassbender, A [School of Oceanography, University of Washington, Seattle, WA; Manke, A [Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration; Malczyk, J [Jetz Laboratory, Department of Ecology and Evolutionary Biology, Yale University; Akl, J [CSIRO Wealth from Oceans Flagship, Hobart, Tasmania, Australia; Alin, S R [Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration; Bellerby, R G J [Geophysical Institute, University of Bergen, Bergen, Norway; Borges, A [University of Liege, Chemical Oceanography Unit, Institut de Physique, Liege, Belgium; Boutin, J [Universite Pierre et Marie Curie, LOCEAN/IPSL, Paris, France; Brown, P J [School of Environmental Sciences, University of East Anglia, Norwich, UK; Cai, W-J [Department of Marine Sciences, University of Georgia; Chavez, F P [Monterey Bay Aquarium Research Institute, Moss Landing, CA; Chen, A [Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan; Cosa, C [Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration; Feely, R A [Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration; Gonzalez-Davila, M [Universidad de Las Palmas de Gran Canaria, Facultad de Ciencias del Mar, Las Palmas de Gran Canaria,; Goyet, C [Institut de Modélisation et d' Analyse en Géo-Environnement et Santé, Université de Perpignan; Hardman-Mountford, N [CSIRO, Marine and Atmospheric Research, Wembley, Western Australia, Australia; Heinze, C [Geophysical Institute, University of Bergen, Bergen, Norway; Hoppema, M [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; Hunt, C W [Ocean Process Analysis Lab, University of New Hampshire, Durham, New Hampshire; Hydes, D [National Oceanography Centre, Southampton, UK; Ishii, M [Japan Meteorological Agency, Meteorological Research Institute, Tsukuba, Japan; Johannessen, T [Geophysical Institute, University of Bergen, Bergen, Norway; Key, R M [Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey; Kortzinger, A [GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany; Landschutzer, P [School of Environmental Sciences, University of East Anglia, Norwich, UK; Lauvset, S K [Geophysical Institute, University of Bergen, Bergen, Norway; Lefevre, N [Université Pierre et Marie Curie, LOCEAN/IPSL, Paris, France; Lenton, A [Centre for Australian Weather and Climate Research, Hobart, Tasmania, Australia; Lourantou, A [Université Pierre et Marie Curie, LOCEAN/IPSL, Paris, France; Merlivat, L [Université Pierre et Marie Curie, LOCEAN/IPSL, Paris, France; Midorikawa, T [Nagasaki Marine Observatory, Nagasaki, Japan; Mintrop, L [MARIANDA, Kiel, Germany; Miyazaki, C [Faculty of Environmental Earth Science, Hokkaido University, Hokkaido, Japan; Murata, A [Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan; Nakadate, A [Marine Division, Global Environment and Marine Department, Japan Meteorological Agency, Tokyo, Japan; Nakano, Y [Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan; Nakaoka, S [National Institute for Environmental Studies (NIES), Tsukuba, Japan; Nojiri, Y [National Institute for Environmental Studies, Tsukuba, Japan; et al.

    2013-01-01

    A well documented, publicly available, global data set for surface ocean carbon dioxide (CO2) parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT) project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC). SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968 2007). The SOCAT gridded data is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust regularly spaced fCO2 product with minimal spatial and temporal interpolation which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet, but also contains biases and limitations that the user needs to recognize and address.

  9. Surface Ocean CO2 Atlas (SOCAT gridded data products

    Directory of Open Access Journals (Sweden)

    T. Steinhoff

    2012-08-01

    Full Text Available A well documented, publicly available, global data set for surface ocean carbon dioxide (CO2 parameters has been called for by international groups for nearly two decades. The Surface Ocean CO2 Atlas (SOCAT project was initiated by the international marine carbon science community in 2007 with the aim of providing a comprehensive, publicly available, regularly updated, global data set of marine surface CO2, which had been subject to quality control (QC. SOCAT version 1.5 was made public in September 2011 and holds 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968–2007. The SOCAT gridded data is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust regularly spaced fCO2 product with minimal spatial and temporal interpolation which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet, but also contains biases and limitations that the user needs to recognize and address.

  10. Surface Ocean CO2 Atlas (SOCAT gridded data products

    Directory of Open Access Journals (Sweden)

    C. L. Sabine

    2013-04-01

    Full Text Available As a response to public demand for a well-documented, quality controlled, publically available, global surface ocean carbon dioxide (CO2 data set, the international marine carbon science community developed the Surface Ocean CO2 Atlas (SOCAT. The first SOCAT product is a collection of 6.3 million quality controlled surface CO2 data from the global oceans and coastal seas, spanning four decades (1968–2007. The SOCAT gridded data presented here is the second data product to come from the SOCAT project. Recognizing that some groups may have trouble working with millions of measurements, the SOCAT gridded product was generated to provide a robust, regularly spaced CO2 fugacity (fCO2 product with minimal spatial and temporal interpolation, which should be easier to work with for many applications. Gridded SOCAT is rich with information that has not been fully explored yet (e.g., regional differences in the seasonal cycles, but also contains biases and limitations that the user needs to recognize and address (e.g., local influences on values in some coastal regions.

  11. Surface CO2 fluxes implied by a full year of OCO-2 column CO2 measurements

    Science.gov (United States)

    Baker, D. F.

    2015-12-01

    Over one year of full-column CO2 concentration data is now available from the Orbiting Carbon Observatory (OCO-2) satellite, with retrieval biases corrected using upward-looking solar spectrometer data from the TCCON network as well with internal consistency checks. We use this OCO-2 data to estimate weekly surface CO2 flux corrections at 6.7ºx6.7º resolution with a variational data assimilation technique built around the off-line PCTM atmospheric transport model driven with MERRA 1ºx1.25° winds and mixing parameters. Since such flux estimates can depend strongly on the prior fluxes assumed (which may remain unchanged in regions of sparse sampling), the initial 3-D concentrations assumed (especially in the upper part of the atmosphere), vertical transport/mixing errors in the model, and un-corrected biases in the satellite data, we invert the OCO-2 data in multiple inversions in which different prior fluxes are used (e.g. SiB4 vs. CASA land bio, Takahashi vs. Doney ocean, FFDAS vs. CDIAC fossil fuel), in which ACOS GOSAT data and NOAA surface in situ and aircraft profile data are used (or not) to correct the prior fluxes and concentration fields, and in which the vertical mixing in the transport model is artificially increased/decreased by a factor of 3, to assess the sensitivity of the OCO-2 flux corrections. These inversions are done in the context of a longer span (2009-2015) to allow the impact of the fluxes and other data sources to fully impact the upper layers of the model. The bias between the OCO-2 data and the prior forward CO2 fields is also calculated before doing the inversions, and compared to similar retrieval biases solved for the ACOS GOSAT data (B3.5). The impact of these bias corrections, as well as the standard ones provided by the OCO-2 team, is assessed by comparing the fit of the a posteriori CO2 fields to independent data (including surface in situ and NOAA aircraft).

  12. Synergetic effect of carbon nanopore size and surface oxidation on CO2 capture from CO2/CH4 mixtures.

    Science.gov (United States)

    Furmaniak, Sylwester; Kowalczyk, Piotr; Terzyk, Artur P; Gauden, Piotr A; Harris, Peter J F

    2013-05-01

    We have studied the synergetic effect of confinement (carbon nanopore size) and surface chemistry (the number of carbonyl groups) on CO2 capture from its mixtures with CH4 at typical operating conditions for industrial adsorptive separation (298 K and compressed CO2-CH4 mixtures). Although both confinement and surface oxidation have an impact on the efficiency of CO2/CH4 adsorptive separation at thermodynamics equilibrium, we show that surface functionalization is the most important factor in designing an efficient adsorbent for CO2 capture. Systematic Monte Carlo simulations revealed that adsorption of CH4 either pure or mixed with CO2 on oxidized nanoporous carbons is only slightly increased by the presence of functional groups (surface dipoles). In contrast, adsorption of CO2 is very sensitive to the number of carbonyl groups, which can be examined by a strong electric quadrupolar moment of CO2. Interestingly, the adsorbed amount of CH4 is strongly affected by the presence of the co-adsorbed CO2. In contrast, the CO2 uptake does not depend on the molar ratio of CH4 in the bulk mixture. The optimal carbonaceous porous adsorbent used for CO2 capture near ambient conditions should consist of narrow carbon nanopores with oxidized pore walls. Furthermore, the equilibrium separation factor was the greatest for CO2/CH4 mixtures with a low CO2 concentration. The maximum equilibrium separation factor of CO2 over CH4 of ~18-20 is theoretically predicted for strongly oxidized nanoporous carbons. Our findings call for a review of the standard uncharged model of carbonaceous materials used for the modeling of the adsorption separation processes of gas mixtures containing CO2 (and other molecules with strong electric quadrupolar moment or dipole moment).

  13. Brine/CO2 Interfacial Properties and Effects on CO2 Storage in Deep Saline Aquifers Propriétés interfaciales saumure/CO2 et effets sur le stockage du CO2 dans des aquifères salins profonds

    Directory of Open Access Journals (Sweden)

    Chalbaud C.

    2010-05-01

    Full Text Available It has been long recognized that interfacial interactions (interfacial tension, wettability, capillarity and interfacial mass transfer govern fluid distribution and behaviour in porous media. Therefore the interfacial interactions between CO2, brine and reservoir oil and/or gas have an important influence on the effectiveness of any CO2 storage operation. There is a lack of experimental data related to interfacial properties for all the geological storage options (oil & gas reservoirs, coalbeds, deep saline aquifers. In the case of deep saline aquifers, there is a gap in data and knowledge of brine-CO2 interfacial properties at storage conditions. More specifically, experimental interfacial tension values and experimental tests in porous media are necessary to better understand the wettability evolution as a function of thermodynamic conditions and it’s effects on fluid flow in the porous media. In this paper, a complete set of experimental values of brine-CO2 Interfaciale Tension (IFT at pressure, temperature and salt concentration conditions representative of those of a CO2 storage operation. A correlation is derived from experimental data published in a companion paper [Chalbaud C., Robin M., Lombard J.-M., Egermann P., Bertin H. (2009 Interfacial Tension Measurements and Wettability Evaluation for Geological CO2 Storage, Adv. Water Resour. 32, 1, 1-109] to model IFT values. This paper pays particular attention to coreflooding experiments showing that the CO2 partially wets the surface in a Intermediate-Wet (IW or Oil-Wet (OW limestone rock. This wetting behavior of CO2 is coherent with observations at the pore scale in glass micromodels and presents a negative impact on the storage capacity of a given site. Il est admis depuis longtemps que les propriétés interfaciales (tension interfaciale, mouillabilité, capillarité et transfert de masse régissent la distribution et le comportement des fluides au sein des milieux poreux. Par cons

  14. Near Surface CO2 Triple Oxygen Isotope Composition

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    Sasadhar Mahata

    2016-02-01

    Full Text Available The isotopic composition of carbon dioxide in the atmosphere is a powerful tool for constraining its sources and sinks. In particular, the 17O oxygen anomaly [Δ17O = 1000 × ln(1 + δ17O/1000 - 0.516 × 1000 × ln(1 + δ18O/1000], with a value > 0.5‰ produced in the middle atmosphere, provides an ideal tool for probing the exchange of carbon dioxide between the biosphere/hydrosphere and atmosphere. The biosphere/hydrosphere and anthropogenic emissions give values ≤ 0.3‰. Therefore, any anomaly in near surface CO2 would reflect the balance between stratospheric input and exchange with the aforementioned surface sources. We have analyzed Δ17O values of CO2 separated from air samples collected in Taipei, Taiwan, located in the western Pacific region. The obtained mean anomaly is 0.42 ± 0.14‰ (1-σ standard deviation, in good agreement with model prediction and a published decadal record. Apart from typically used δ13C and δ18O values, the Δ17O value could provide an additional tracer for constraining the carbon cycle.

  15. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements

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    C. A. M. Brenninkmeijer

    2011-02-01

    Full Text Available We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America, which the joint inversion suggests was a weak sink of −0.17 ± 0.20 Pg C in 2006. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion yields −1.13 ± 0.21 Pg C for the global ocean, −2.77 ± 0.20 Pg C for the global land biosphere and −3.90 ± 0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion. These global ocean, global land and total global fluxes are shown to be in the range of other inversion results for 2006. To achieve these results, a latitude dependent bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for

  16. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-06-01

    Full Text Available We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion for the year 2006 yields −1.13±0.21 Pg C for the global ocean, −2.77±0.20 Pg C for the global land biosphere and −3.90±0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion. These global ocean and global land fluxes are shown to be near the median of the broad range of values from other inversion results for 2006. To achieve these results, a bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for flux inversions.

  17. Measuring water adsorption on mineral surfaces in air, CO2, and supercritical CO2 with a quartz-crystal microbalance

    Science.gov (United States)

    Bryan, C. R.; Wells, R. K.; Burton, P. D.; Heath, J. E.; Dewers, T. A.; Wang, Y.

    2011-12-01

    Carbon sequestration via underground storage in geologic formations is a proposed approach for reducing industrial CO2 emissions. However, current models for carbon injection and long-term storage of supercritical CO2 (scCO2) do not consider the development and stability of adsorbed water films at the scCO2-hydrophilic mineral interface. The thickness and properties of the water films control the surface tension and wettability of the mineral surface, and on the core scale, affect rock permeability, saturation, and capillary properties. The film thickness is strongly dependent upon the activity of water in the supercritical fluid, which will change as initially anhydrous scCO2 absorbs water from formation brine. As described in a companion paper by the coauthors, the thickness of the adsorbed water layer is controlled by the disjoining pressure; structural and van der Waals components dominate at low water activity, while electrostatic forces become more important with increasing film thickness (higher water activities). As scCO2 water activity and water layer thickness increase, concomitant changes in mineral surface properties and reservoir/caprock hydrologic properties will affect the mobility of the aqueous phase and of scCO2. Moreover, the development of a water layer may be critical to mineral dissolution reactions in scCO2. Here, we describe the use of a quartz-crystal microbalance (QCM) to monitor adsorption of water by mineral surfaces. QCMs utilize a piezoelectrically-stimulated quartz wafer to measure adsorbed or deposited mass via changes in vibrational frequency. When used to measure the mass of adsorbed liquid films, the frequency response of the crystal must be corrected for the viscoelastic, rather than elastic, response of the adsorbed layer. Results are presented for adsorption to silica in N2 and CO2 at one bar, and in scCO2. Additional data are presented for water uptake by clays deposited on a QCM wafer. In this case, water uptake occurs by the

  18. Geophysical monitoring of near surface CO2 injection at Svelvik - Learnings from the CO2FieldLab experiments.

    Science.gov (United States)

    Querendez, Etor; Romdhane, Anouar; Jordan, Michael; Eliasson, Peder; Grimstad, Alv-Arne

    2014-05-01

    A CO2 migration field laboratory for testing monitoring methods and tools has been established in the glaciofluvial-glaciomarine Holocene deposits of the Svelvik ridge, near Oslo (Norway). At the site, feasibility, sensitivity, acquisition geometry and usefulness of various surface and subsurface monitoring tools are investigated during controlled CO2 injection experiments. In a first stage, a shallow CO2 injection experiment was conducted in September 2011. Approximately 1700 kg of CO2 was injected at 18 m depth below surface in an unconsolidated sand formation. The objectives of this experiment were to (i) detect and, where possible, quantify migrated CO2 concentrations at the surface and very shallow subsurface, (ii) evaluate the sensitivity of the monitoring tools and (iii) study the impact of the vadose zone on observed measurements. Results showed that all deployed monitoring tools (for surface and near-surface gas monitoring, subsurface water monitoring and subsurface geophysical monitoring) where able to detect the presence of CO2 even though the CO2 plume did not migrate vertically as expected in what was thought to be an homogeneous unconsolidated sand structure. The upper part of the site revealed to be more heterogeneous than expected, mainly due to the highly variable lamination and channelling of the morainic sediments and to the presence of pebble and cobble beds sporadically showing throughout the deposits. Building on the learnings from the 18m depth injection experiment, a second experiment is being planned for a deeper injection, at a depth of 65m. Re-processing of the appraisal 2D multi-channel seismic with state-of-the-art processing techniques, like Linear Radon coherent and random noise attenuation and Full Waveform Inversion followed by pre-stack depth migration, corroborate the presence of heterogeneities at the near surface. Based on the re-interpreted seismic sections, a more realistic 3D geomodel, where the complex topography of the site

  19. Atmosphere–Surface Fluxes of CO2 using Spectral Techniques

    DEFF Research Database (Denmark)

    Sørensen, Lise Lotte; Larsen, Søren Ejling

    2010-01-01

    Different flux estimation techniques are compared here in order to evaluate air–sea exchange measurement methods used on moving platforms. Techniques using power spectra and cospectra to estimate fluxes are presented and applied to measurements of wind speed and sensible heat, latent heat and CO2...

  20. Long-term CO2 injection and its impact on near-surface soil microbiology.

    Science.gov (United States)

    Gwosdz, Simone; West, Julia M; Jones, David; Rakoczy, Jana; Green, Kay; Barlow, Tom; Blöthe, Marco; Smith, Karon; Steven, Michael; Krüger, Martin

    2016-12-01

    Impacts of long-term CO2 exposure on environmental processes and microbial populations of near-surface soils are poorly understood. This near-surface long-term CO2 injection study demonstrated that soil microbiology and geochemistry is influenced more by seasonal parameters than elevated CO2 Soil samples were taken during a 3-year field experiment including sampling campaigns before, during and after 24 months of continuous CO2 injection. CO2 concentrations within CO2-injected plots increased up to 23% during the injection period. No CO2 impacts on geochemistry were detected over time. In addition, CO2-exposed samples did not show significant changes in microbial CO2 and CH4 turnover rates compared to reference samples. Likewise, no significant CO2-induced variations were detected for the abundance of Bacteria, Archaea (16S rDNA) and gene copy numbers of the mcrA gene, Crenarchaeota and amoA gene. The majority (75%-95%) of the bacterial sequences were assigned to five phyla: Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes The majority of the archaeal sequences (85%-100%) were assigned to the thaumarchaeotal cluster I.1b (soil group). Univariate and multivariate statistical as well as principal component analyses showed no significant CO2-induced variation. Instead, seasonal impacts especially temperature and precipitation were detected. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Monitoring of CO2 geological storage based on the passive surface waves

    Institute of Scientific and Technical Information of China (English)

    Dai Kaoshan; Li Xiaofeng; Song Xuehang; Chen Gen; Pan Yongdong; Huang Zhenhua

    2014-01-01

    Carbon dioxide (CO2) capture and geological storage (CCS) is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, among which effectively detecting CO2 from deep underground is one of engineering problems. This paper reviews monitoring techniques currently used during CO2 injection and storage. A method developed based on measuring seismic microtremors is of main interest. This method was first successfully used to characterize a site in this paper. To explore its feasibility in CO2 storage monitoring, numerical simulations were conducted to investigate detectable changes in elastic wave signatures due to injection and geological storage of CO2. It is found that, although it is effective for shallow earth profile estimation, the surface wave velocity is not sensitive to the CO2 layer physical parameter variations, especially for a thin CO2 geological storage layer in a deep underground reservoir.

  2. Technical note: Evaluation of three machine learning models for surface ocean CO2 mapping

    Science.gov (United States)

    Zeng, Jiye; Matsunaga, Tsuneo; Saigusa, Nobuko; Shirai, Tomoko; Nakaoka, Shin-ichiro; Tan, Zheng-Hong

    2017-04-01

    Reconstructing surface ocean CO2 from scarce measurements plays an important role in estimating oceanic CO2 uptake. There are varying degrees of differences among the 14 models included in the Surface Ocean CO2 Mapping (SOCOM) inter-comparison initiative, in which five models used neural networks. This investigation evaluates two neural networks used in SOCOM, self-organizing maps and feedforward neural networks, and introduces a machine learning model called a support vector machine for ocean CO2 mapping. The technique note provides a practical guide to selecting the models.

  3. CO2 adsorption and separation from natural gason phosphorene surface: Combining DFT and GCMC calculations

    Science.gov (United States)

    Zhang, Yayun; Liu, Chao; Hao, Feng; Xiao, Hang; Zhang, Shiwei; Chen, Xi

    2017-03-01

    We have examined the performance of phosphorene-based material, phosphorene slit pores (PSP), in CO2 adsorption and separation from natural gas by using Density Function Theory (DFT) calculation and Grand Canonical Monte Carlo (GCMC) simulations. First, the adsorption of CH4 and CO2molecules on phosphorene sheet were conducted by DFT study. Then, adsorption performances of natural gas components as well as their binary CO2/CH4 gas mixture were investigated at 300 K with the pressure up to 3.0 MPa. The effects of slit pore width, H, and mole ratio of CO2/CH4in the gas phase on the separation of CO2 from mixtures of CO2/CH4 were also investigated. Our DFT calculation results show that the CO2 moleculehas higher adsorption energy than that of CH4, which implies that it can be easily adsorbed to the phosphorene surface than CH4. Detailed GCMC simulations reveal that the phosphorene slit pore has a high performance in separating CO2fromnature gas and achieves the highest gas selectivity at H = 1.0 nm at pressures lower than 0.1 MPa. Moreover, the selectivity of CO2 overCO2/CH4gas mixture increases with increasing the mole ratio of CO2/CH4due to the enhanced adsorbate-adsorbent interactions for the favorable component. Therefore, it is suggested that the phosphorene is a promising candidate for natural gas purification and possessing practical potential applications in gas adsorption.

  4. Effect of pore size and surface chemistry of porous silica on CO2 adsorption

    Directory of Open Access Journals (Sweden)

    Thongthai Witoon

    2012-09-01

    Full Text Available In the present study, porous silica synthesized using sodium silicate as a low-cost raw material was selected as a CO2sorbent. The effects of pore size and amount of silanol content on CO2 adsorption capacity were investigated. The physicalproperties and surface chemistry (silanol content of the porous silica products were characterized by means of N2-physisorption, Fourier transform infrared spectroscopy and thermogravimetric analysis technique. The pore size of the poroussilica materials did not affect the equilibrium CO2 capacity; however the porous silica with large pore size could enhance thediffusion of CO2. The amount of silanol content was found to be a key factor for the CO2 adsorption capacity. A greater CO2adsorption capacity would be obtained with an increase of the silanol concentration on the surface of the porous silicamaterials.

  5. Tuning the Surface Polarity of Microporous Organic Polymers for CO2 Capture.

    Science.gov (United States)

    Chen, Jian; Li, He; Zhong, Mingmei; Yang, Qihua

    2017-09-05

    CO2 capture is very important to reduce the CO2 concentration in atmosphere. Herein, we report the preparation of microporous polymers with tunable surface polarity for CO2 capture. Porous polymers functionalized with -NH2 , -SO3 H, and -SO3 Li have been successfully prepared by using a post-synthesis modification of microporous polymers (P-PhPh3 prepared with 1,3,5-triphenylbenzene as the monomer and AlCl3 as the catalyst) by chemical transformations, such as nitration-reduction, sulfonation, and cationic exchange. The CO2 adsorption selectivity (CO2 /N2 and CO2 /H2 ) and isosteric heats of the microporous polymers increase markedly after modification, P-PhPh3 -NH2 and P-PhPh3 -SO3 Li afford higher CO2 uptake capacity than P-PhPh3 at pressures of less than 0.15 bar due to the enhanced interaction between CO2 and the -NH2 and -SO3 Li functional groups. Moreover, functionalized porous polymers could be stably used for CO2 capture. Surface modification is an efficient approach to tune the CO2 capture properties of porous polymers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Climatological mean and decadal change in surface ocean pCO2, and net sea–air CO2 flux over the global oceans

    NARCIS (Netherlands)

    Takahashi, Taro; Sutherland, Stewart C.; Wanninkhof, Rik; Sweeney, Colm; Feely, Richard A.; Chipman, David W.; Hales, Burke; Friederich, Gernot; Chavez, Francisco; Sabine, Christopher; Watson, Andrew; Bakker, Dorothee C.E.; Schuster, Ute; Metzl, Nicolas; Yoshikawa-Inoue, Hisayuki; Ishii, Masao; Midorikawa, Takashi; Nojiri, Yukihiro; Körtzinger, Arne; Steinhoff, Tobias; Hoppema, Mario; Olafsson, Jon; Arnarson, Thorarinn S.; Tilbrook, Bronte; Johannessen, Truls; Olsen, Are; Bellerby, Richard; Wong, C.S.; Delille, Bruno; Bates, N.R.; Baar, Hein J.W. de

    2009-01-01

    A climatological mean distribution for the surface water pCO2 over the global oceans in non-El Niño conditions has been constructed with spatial resolution of 4° (latitude) ×5° (longitude) for a reference year 2000 based upon about 3 million measurements of surface water pCO2 obtained from 1970 to 2

  7. Surface modification and enhanced photocatalytic CO2 reduction performance of TiO2: a review

    Science.gov (United States)

    Low, Jingxiang; Cheng, Bei; Yu, Jiaguo

    2017-01-01

    Recently, the excessive consumption of fossil fuels has caused high emissions of the greenhouse gases, CO2 into atmosphere and global energy crisis. Mimicking the natural photosynthesis by using semiconductor materials to achieve photocatalytic CO2 reduction into valuable solar fuels such as CH4, HCO2H, CH2O, and CH3OH is known as one of the best solutions for addressing the aforementioned issue. Among various proposed photocatalysts, TiO2 has been extensively studied over the past several decades for photocatalytic CO2 reduction because of its cheapness and environmental friendliness. Particularly, surface modification of TiO2 has attracted numerous interests due to its capability of enhancing the light absorption ability, facilitating the electron-hole separation, tuning the CO2 reduction selectivity and increasing the CO2 adsorption and activation ability of TiO2 for photocatalytic CO2 reduction. In this review, recent approaches of the surface modification of TiO2 for photocatalytic CO2 reduction, including impurity doping, metal deposition, alkali modification, heterojunction construction and carbon-based material loading, are presented. The photocatalytic CO2 reduction mechanism and pathways of TiO2 are discussed. The future research direction and perspective of photocatalytic CO2 reduction over surface-modified TiO2 are also presented.

  8. Surface abundance change in vacuum ultraviolet photodissociation of CO2 and H2O mixture ices.

    OpenAIRE

    Kinugawa, Takashi; Yabushita, Akihiro; Kawasaki, Masahiro; Hama, Tetsuya; Watanabe, Naoki

    2011-01-01

    Photodissociation of amorphous ice films of carbon dioxide and water co-adsorbed at 90 K was carried out at 157 nm using oxygen-16 and -18 isotopomers with a time-of-flight photofragment mass spectrometer. O((3)P(J)) atoms, OH (v = 0) radicals, and CO (v = 0, 1) molecules were detected as photofragments. CO is produced directly from the photodissociation of CO(2). Two different adsorption states of CO(2), i.e., physisorbed CO(2) on the surface of amorphous solid water and trapped CO(2) in the...

  9. Critical evaluation of 13C natural abundance techniques to partition soil-surface CO2 efflux

    Science.gov (United States)

    Snell, H.; Midwood, A. J.; Robinson, D.

    2013-12-01

    Soil is the largest terrestrial store of carbon and the flux of CO2 from soils to the atmosphere is estimated at around 98 Pg (98 billion tonnes) of carbon per year. The CO2 efflux from the soil surface is derived from plant root and rhizosphere respiration (autotrophically fuelled) and microbial degradation of soil organic matter (heterotrophic respiration). Heterotrophic respiration is a key determinant of an ecosystem's long-term C balance, but one that is difficult to measure in the field. One approach involves partitioning the total soil-surface CO2 efflux between heterotrophic and autotrophic components; this can be done using differences in the natural abundance stable isotope ratios (δ13C) of autotrophic and heterotrophic CO2 as the end-members of a simple mixing model. In most natural, temperate ecosystems, current and historical vegetation cover (and therefore also plant-derived soil organic matter) is produced from C3 photosynthesis so the difference in δ13C between the autotrophic and heterotrophic CO2 sources is small. Successful partitioning therefore requires accurate and precise measurements of the δ13CO2 of the autotrophic and heterotrophic end-members (obtained by measuring the δ13CO2 of soil-free roots and root-free soil) and of total soil CO2 efflux. There is currently little consensus on the optimum measurement protocols. Here we systematically tested some of the most commonly used techniques to identify and minimise methodological errors. Using soil-surface chambers to sample total CO2 efflux and a cavity ring-down spectrometer to measure δ13CO2 in a partitioning study on a Scottish moorland, we found that: using soil-penetrating collars leads to a more depleted chamber measurement of total soil δ13CO2 as a result of severing roots and fungal hyphae or equilibrating with δ13CO2 at depth or both; root incubations provide an accurate estimate of in-situ root respired δ13CO2 provided they are sampled within one hour; the δ13CO2 from root

  10. Surface Ocean pCO2 Seasonality and Sea-Air CO2 Flux Estimates for the North American East Coast

    Science.gov (United States)

    Signorini, Sergio; Mannino, Antonio; Najjar, Raymond G., Jr.; Friedrichs, Marjorie A. M.; Cai, Wei-Jun; Salisbury, Joe; Wang, Zhaohui Aleck; Thomas, Helmuth; Shadwick, Elizabeth

    2013-01-01

    Underway and in situ observations of surface ocean pCO2, combined with satellite data, were used to develop pCO2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO2 and sea-air CO2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NS+GB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO2. Estimates of the sea-air CO2 flux were derived from the available pCO2 data, as well as from the pCO2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GB+NS, MAB, and SAB regions are net sinks of atmospheric CO2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO2 by eastern North American continental shelf waters is found to be between 3.4 and 5.4 Tg C/yr (areal average of 0.7 to 1.0 mol CO2 /sq m/yr) over the period 2003-2010.

  11. Surface energy, CO2 fluxes and sea ice

    CSIR Research Space (South Africa)

    Gulev, SK

    2009-09-01

    Full Text Available , there are serious concerns about the recent decline in the number of VOS observations. Closure of global and regional energy balances still cannot be achieved without adjustments to the flux fields and/or the underlying surface meteorological variables. The impact...

  12. A leak monitoring method for CO2 storage sites using ratio of ∆CO2:∆O2 at the soil surface

    Science.gov (United States)

    Alam, M. M.; Norman, A. L.; Layzell, D. B.; Amiri, N.

    2016-12-01

    Carbon Capture and Storage (CCS) technology has a high potential for reducing carbon emission at large scales. However, the success of CCS projects vastly depends on the continuous monitoring of injected CO2 and ensuring it remains below ground. The technology currently available for monitoring sites are mainly adopted from disciplines which are effective at detecting high volume leaks but may not be reliable in distinguishing seepage of CO2 from underground and fossil fuel combustion at the surface. We have constructed a numerical model that includes soil characteristics and the bio-geo-chemical dynamics of near surface soils and soil gases. The simulation of our model can predict O2 and CO2 profiles in soil and differential ratios with respect to atmospheric concentrations (∆CO2 and ∆O2), and distinguish CO2 leaks. Experiments on a 1-m soil column have been conducted using dual channel IR and fuel cell analyzers to verify our model predictions. The preliminary results show that measured O2 and CO2 concentrations in near-surface soil layers and the ratio of ∆CO2:∆O2 at the soil surface are in agreement with our model. Based on initial results it is expected that this method of monitoring will able to detect fluxes as small as 2-6µmole/m2/s of CO 2 leakage.

  13. Maintenance sur les infrastructures de surface

    CERN Document Server

    Chevret, P

    2000-01-01

    L'objet de ce document est de dresser le bilan de l'activité du Groupe Technical Facilities Management dans le domaine de la maintenance. Ce bilan couvre les activités techniques du génie civil, du chauffage-climatisation et de l'électricité, s'appliquant dans une large majorité au seul secteur tertiaire, tant sur le plan préventif que correctif. Les principaux paramètres indicateurs de l'activité sont situés dans leur évolution au cours des dernières années. Les auteurs abordent également les principaux projets complémentaires de maintenance, qui sont conduits pour maintenir l'état du patrimoine en dépit des restrictions budgétaires, faire face aux problèmes d'obsolescence, de défaillances récurrentes sur certains matériels, et satisfaire aux normes de sécurité. L'incidence positive de ces actions sur le nombre d'interventions de maintenance corrective est également montrée. Enfin, des perspectives de progrès sont dégagées, visant à une gestion davantage prévisionnelle de la ma...

  14. Parameterization of atmosphere–surface exchange of CO2 over sea ice

    DEFF Research Database (Denmark)

    Sørensen, Lise Lotte; Jensen, Bjarne; Glud, Ronnie;

    2014-01-01

    are discussed. We found the flux to be small during the late winter with fluxes in both directions. Not surprisingly we find that the resistance across the surface controls the fluxes and detailed knowledge of the brine volume and carbon chemistry within the brines as well as knowledge of snow cover and carbon...... chemistry in the ice are essential to estimate the partial pressure of pCO2 and CO2 flux. Further investigations of surface structure and snow cover and driving parameters such as heat flux, radiation, ice temperature and brine processes are required to adequately parameterize the surface resistance.......We suggest the application of a flux parameterization commonly used over terrestrial areas for calculation of CO2 fluxes over sea ice surfaces. The parameterization is based on resistance analogy.We present a concept for parameterization of the CO2 fluxes over sea ice suggesting to use properties...

  15. The Partial Density of States of CO2 Molecules Adsorption on the Fe (111) Surface

    Science.gov (United States)

    Wu, Junfang

    2017-09-01

    The state of CO2 molecules adsorption on Fe (111) surface is studied by simulation with the software, the partial density of states the adsorption is obtained. Through the graphical distribution, the pseudogap and the partial density of states at the Fermi level of the CO2 molecules adsorption on the Fe (111) surface is analyzed and compared. The key mechanism of CO2 molecules adsorption on the Fe (111) surface is revealed. The results showed that the CO2 molecules adsorption on the bridge position of Fe (111) surface is stable. The main reason of O atom and Fe atom combining with the bonding is that the resonance of the density of states happed between the O 2p orbital and Fe 3d orbital.

  16. Role of specific amine surface configurations for grafted surfaces: implications for nanostructured CO2 adsorbents.

    Science.gov (United States)

    Shimizu, Steven; Song, Changsik; Strano, Michael

    2011-03-15

    Amine-grafted porous materials that capture CO2 from emission streams have been considered to be potential alternatives to the more energy-intensive liquid amine systems currently employed. An underappreciated fact in the uptake mechanism of these materials is that under dry, anhydrous conditions each CO2 molecule must react with two adjacent amine groups to adsorb onto the surface, which makes the configuration of amine groups on the surface critically important. Using this chemical mechanism, we developed a semiempirical adsorption isotherm equation that allows straightforward computation of the adsorption isotherm from an arbitrary surface configuration of grafted amines for honeycomb, square, and triangular lattices. The model makes use of the fact that the distribution of amines with respect to the number of nearest neighbors, referred to as the z-histogram, along with the amine loading and equilibrium constant, uniquely determine the adsorption characteristics to a very good approximation. This model was used to predict the range of uptakes possible just through surface configuration, and it was used to fit experimental data in the literature to give a meaningful equilibrium constant and show how efficiently amines were utilized. We also demonstrate how the model can be utilized to design more efficient nanostructured adsorbents and polymer-based adsorbents. Recommendations for exploiting the role of surface configuration include the use of linear instead of branched polyamines, higher amine grafting densities, the use of flexible, less bulky, long, and rotationally free amine groups, and increased silanol densities.

  17. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-02-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0degree of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. It is evident, from this analysis, that SCIAMACHY therefore has the potential to

  18. Assessing the near surface sensitivity of SCIAMACHY atmospheric CO2 retrieved using (FSI WFM-DOAS

    Directory of Open Access Journals (Sweden)

    N. Vinnichenko

    2007-07-01

    Full Text Available Satellite observations of atmospheric CO2 offer the potential to identify regional carbon surface sources and sinks and to investigate carbon cycle processes. The extent to which satellite measurements are useful however, depends on the near surface sensitivity of the chosen sensor. In this paper, the capability of the SCIAMACHY instrument on board ENVISAT, to observe lower tropospheric and surface CO2 variability is examined. To achieve this, atmospheric CO2 retrieved from SCIAMACHY near infrared (NIR spectral measurements, using the Full Spectral Initiation (FSI WFM-DOAS algorithm, is compared to in-situ aircraft observations over Siberia and additionally to tower and surface CO2 data over Mongolia, Europe and North America. Preliminary validation of daily averaged SCIAMACHY/FSI CO2 against ground based Fourier Transform Spectrometer (FTS column measurements made at Park Falls, reveal a negative bias of about −2.0% for collocated measurements within ±1.0° of the site. However, at this spatial threshold SCIAMACHY can only capture the variability of the FTS observations at monthly timescales. To observe day to day variability of the FTS observations, the collocation limits must be increased. Furthermore, comparisons to in-situ CO2 observations demonstrate that SCIAMACHY is capable of observing a seasonal signal that is representative of lower tropospheric variability on (at least monthly timescales. Out of seventeen time series comparisons, eleven have correlation coefficients of 0.7 or more, and have similar seasonal cycle amplitudes. Additional evidence of the near surface sensitivity of SCIAMACHY, is provided through the significant correlation of FSI derived CO2 with MODIS vegetation indices at over twenty selected locations in the United States. The SCIAMACHY/MODIS comparison reveals that at many of the sites, the amount of CO2 variability is coincident with the amount of vegetation activity. The presented analysis suggests that

  19. Impact of Siberian observations on the optimization of surface CO2 flux

    Science.gov (United States)

    Kim, Jinwoong; Kim, Hyun Mee; Cho, Chun-Ho; Boo, Kyung-On; Jacobson, Andrew R.; Sasakawa, Motoki; Machida, Toshinobu; Arshinov, Mikhail; Fedoseev, Nikolay

    2017-02-01

    To investigate the effect of additional CO2 observations in the Siberia region on the Asian and global surface CO2 flux analyses, two experiments using different observation data sets were performed for 2000-2009. One experiment was conducted using a data set that includes additional observations of Siberian tower measurements (Japan-Russia Siberian Tall Tower Inland Observation Network: JR-STATION), and the other experiment was conducted using a data set without the above additional observations. The results show that the global balance of the sources and sinks of surface CO2 fluxes was maintained for both experiments with and without the additional observations. While the magnitude of the optimized surface CO2 flux uptake and flux uncertainty in Siberia decreased from -1.17 ± 0.93 to -0.77 ± 0.70 Pg C yr-1, the magnitude of the optimized surface CO2 flux uptake in the other regions (e.g., Europe) of the Northern Hemisphere (NH) land increased for the experiment with the additional observations, which affect the longitudinal distribution of the total NH sinks. This change was mostly caused by changes in the magnitudes of surface CO2 flux in June and July. The observation impact measured by uncertainty reduction and self-sensitivity tests shows that additional observations provide useful information on the estimated surface CO2 flux. The average uncertainty reduction of the conifer forest of Eurasian boreal (EB) is 29.1 % and the average self-sensitivities at the JR-STATION sites are approximately 60 % larger than those at the towers in North America. It is expected that the Siberian observations play an important role in estimating surface CO2 flux in the NH land (e.g., Siberia and Europe) in the future.

  20. Quantification of the advected CO2 concentration due to upstream surface fluxes in aircraft vertical profiles

    Science.gov (United States)

    Font, A.; Morguí, J.-A.; Curcoll, R.; Rodó, X.

    2009-04-01

    A model framework which couples the Lagrangian Particle Dispersion Model FLEXPART (LPDM) with the new global surface flux inversion CarbonTracker from NOAA-ESRL (2007B release) is used to quantify the advected CO2 concentration from outbound surface fluxes to measured vertical profiles carried out during different seasons in 2006 at La Muela site in Spain (LMU; 41.60°N, 1.1°W). The Lagrangian Particle Dispersion Model FLEXPART (LPDM) calculates the influence of surface CO2 fluxes upwind of the study area, allowing us to identify those sources or sink areas that strongly modify the CO2 content of air masses that arrives at different altitudes of measured profiles. CarbonTracker is a new assimilation system that informs of global carbon fluxes at 1°x1° at 3 hours resolution. Coupling LPDM results with surface fluxes allows assessing the net CO2 contribution of identified areas to measured concentrations along the profiles above a reference or background concentration. Furthermore, it allows the quantification of the percentage of each component flux (biospheric, anthropogenic and oceanic) to each vertical layer. At LMU, biospheric fluxes account ~70% of total CO2 advection; fossil fuel ~25%; and ~5% is attributed to the oceanic ones. By far, late spring and summer profiles are largely influence by the biospheric component (~90%). Finally, the CO2 concentration above the background value of profiles measured on 22nd February, 13th October and 30th November 2006 are well explained by the advection of upstream surface fluxes. In other profiles examined, the variation of CO2 along the profile is partially explained by the advection of CO2 outbound fluxes.

  1. First-principles investigation of CO2 absorption on III-nitride surfaces

    Science.gov (United States)

    Chen, Ying-Chin; Guo, Hong

    2015-03-01

    Photon-induced chemical transformation of CO2 is a very interesting direction of green-house gas reduction. An accurate description of electronic structure at the interface between CO2 and the photocatalytics is important for understanding the process of artificial photosynthesis. In this work we report density functional theory (DFT) and many-body GW calculations to investigate CO2 adsorption on III-nitride semiconductor surface. The adsorption geometry is determined at the DFT level and the electronic structure is investigated at both DFT and GW levels. A detailed illustration of how the molecular orbital is renormalized is addressed.

  2. A controlled field pilot for testing near surface CO2 detection techniques and transport models

    Science.gov (United States)

    Spangler, L.H.; Dobeck, L.M.; Repasky, K.; Nehrir, A.; Humphries, S.; Keith, C.; Shaw, J.; Rouse, J.; Cunningham, A.; Benson, S.; Oldenburg, C.M.; Lewicki, J.L.; Wells, A.; Diehl, R.; Strazisar, B.; Fessenden, J.; Rahn, Thomas; Amonette, J.; Barr, J.; Pickles, W.; Jacobson, J.; Silver, E.; Male, E.; Rauch, H.; Gullickson, K.; Trautz, R.; Kharaka, Y.; Birkholzer, J.; Wielopolski, L.

    2009-01-01

    A field facility has been developed to allow controlled studies of near surface CO2 transport and detection technologies. The key component of the facility is a shallow, slotted horizontal well divided into six zones. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects. A wide variety of detection techniques were deployed by collaborators from 6 national labs, 2 universities, EPRI, and the USGS. Additionally, modeling of CO2 transport and concentrations in the saturated soil and in the vadose zone was conducted. An overview of these results will be presented. ?? 2009 Elsevier Ltd. All rights reserved.

  3. Surface abundance change in vacuum ultraviolet photodissociation of CO2 and H2O mixture ices.

    Science.gov (United States)

    Kinugawa, Takashi; Yabushita, Akihiro; Kawasaki, Masahiro; Hama, Tetsuya; Watanabe, Naoki

    2011-09-21

    Photodissociation of amorphous ice films of carbon dioxide and water co-adsorbed at 90 K was carried out at 157 nm using oxygen-16 and -18 isotopomers with a time-of-flight photofragment mass spectrometer. O((3)P(J)) atoms, OH (v = 0) radicals, and CO (v = 0,1) molecules were detected as photofragments. CO is produced directly from the photodissociation of CO(2). Two different adsorption states of CO(2), i.e., physisorbed CO(2) on the surface of amorphous solid water and trapped CO(2) in the pores of the film, are clearly distinguished by the translational and internal energy distributions of the CO molecules. The O atom and OH radical are produced from the photodissociation of H(2)O. Since the absorption cross section of CO(2) is smaller than that of H(2)O at 157 nm, the CO(2) surface abundance is relatively increased after prolonged photoirradiation of the mixed ice film, resulting in the formation of a heterogeneously layered structure in the mixed ice at low temperatures. Astrophysical implications are discussed.

  4. Characterization of Qatar's surface carbonates for CO2 capture and thermochemical energy storage

    Science.gov (United States)

    Kakosimos, Konstantinos E.; Al-Haddad, Ghadeer; Sakellariou, Kyriaki G.; Pagkoura, Chrysa; Konstandopoulos, Athanasios G.

    2017-06-01

    Samples of surface carbonates were collected from three different areas of the Qatar peninsula. We employed material characterization techniques to examine the morphology and composition of the samples, while their CO2 capture capacity was assessed via multiple successive calcination-carbonation cycles. Our samples were mainly calcite and dolomite based. Calcite samples showed higher initial capacity of around 11 mmol CO2 g-1 which decayed rapidly to less than 2 mmol CO2 g-1. On the other hand, dolomite samples showed an excellent stability (˜15 cycles) with a capacity of 6 mmol CO2 g-1. The performance of the dolomite samples is better compared to other similar natural samples, from literature. A promising result for future studies towards improving their performance by physical and chemical modification.

  5. [Optimization for supercritical CO2 extraction with response surface methodology of Prunus armeniaca oil].

    Science.gov (United States)

    Chen, Fei-Fei; Wu, Yan; Ge, Fa-Huan

    2012-03-01

    To optimize the extraction conditions of Prunus armeniaca oil by Supercritical CO2 extraction and identify its components by GC-MS. Optimized of SFE-CO extraction by response surface methodology and used GC-MS to analysis Prunus armeniaca oil compounds. Established the model of an equation for the extraction rate of Prunus armeniaca oil by supercritical CO2 extraction, and the optimal parameters for the supercritical CO2 extraction determined by the equation were: the extraction pressure was 27 MPa, temperature was 39 degrees C, the extraction rate of Prunus armeniaca oil was 44.5%. 16 main compounds of Prunus armeniaca oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 92.6%. This process is simple, and can be used for the extraction of Prunus armeniaca oil.

  6. The importance of surface morphology in controlling the selectivity of polycrystalline copper for CO(2) electroreduction

    DEFF Research Database (Denmark)

    Tang, Wei; Peterson, Andrew A; Varela Gasque, Ana Sofia

    2012-01-01

    This communication examines the effect of the surface morphology of polycrystalline copper on electroreduction of CO(2). We find that a copper nanoparticle covered electrode shows better selectivity towards hydrocarbons compared with the two other studied surfaces, an electropolished copper elect...

  7. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    Science.gov (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  8. Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

    Science.gov (United States)

    Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

    2015-12-15

    Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

  9. El bioclima humano en urbes del sur de México para condiciones de duplicación de CO2 atmosférico

    Directory of Open Access Journals (Sweden)

    Adalberto Tejeda Martínez

    2003-01-01

    Full Text Available A partir del concepto de temperatura efectiva (TE, se presenta un escenario de las condiciones de bioclima humano de ocho ciudades importantes del sur de México, obtenido de predicciones regionales de modelos de circulación general para el caso de una duplicación en la concentración atmosférica global de CO2. Los resultados se ilustran con gráficas de las condiciones de confort actuales y futuras para el sur del país. Se encontró que, pese a los procesos de aclimatación, se intensificarán las sensaciones cálidas debido al efecto invernadero. Combinando lo anterior con proyecciones conservadoras del incremento de la población para la segunda mitad del siglo XXI, se estima que las ciudades de clima cálido quintuplicarán las necesidades de enfriamiento para obtener el confort de sus habitantes.

  10. El bioclima humano en urbes del sur de México para condiciones de duplicación de CO2 atmosférico

    Directory of Open Access Journals (Sweden)

    Adalberto Tejeda Martínez

    2012-02-01

    Full Text Available . A partir del concepto de temperatura efectiva (TE, se presenta un escenario de las condiciones de bioclima humano de ocho ciudades importantes del sur de México, obtenido de predicciones regionales de modelos de circulación general para el caso de una duplicación en la concentración atmosférica global de CO2. Los resultados se ilustran con gráficas de las condiciones de confort actuales y futuras para el sur del país. Se encontró que, pese a los procesos de aclimatación, se intensificarán las sensaciones cálidas debido al efecto invernadero. Combinando lo anterior con proyecciones conservadoras del incremento de la población para la segunda mitad del siglo XXI, se estima que las ciudades de clima cálido quintuplicarán las necesidades de enfriamiento para obtener el confort de sus habitantes.

  11. Spatiotemporal trends in surface seawater CO2 in the Gulf of Mexico

    Science.gov (United States)

    Kealoha, A. K.; Shamberger, K.

    2016-12-01

    The Gulf of Mexico (GoM) contains many interconnected ecosystems intimately linked to regional economic stability through fisheries. Yet, numerous human pressures, including eutrophication-induced hypoxia and ocean acidification (OA), threaten the health of this large marine ecosystem. A comprehensive characterization of the drivers of GoM seawater CO2 cycling is required to assess interactions between these local stresses, global climate change, and OA. Several observational and modeling studies have been conducted in an effort to characterize CO2-system trends within the GoM. However, observational studies are limited to specific regions and time-frames, while modeled data are based on parameterizations that often cannot account for all the biogeochemical processes occurring in this complex system. Here, we present a compilation of approximately 510,000 continuous, underway measurements of sea surface temperature, salinity and seawater CO2, collected from 1996-2013 throughout the entire GoM. These data reveal distinct spatial and temporal CO2 trends that are driven primarily by temperature, Mississippi River outflow, biological productivity, and water circulation. For example, during the spring and summer, nutrient input from the Mississippi River stimulates biological productivity that drives surface seawater CO2 below atmospheric levels in the north-central GoM shelf waters. Although open ocean waters are generally a source of CO2 to the atmosphere in the summer, a unique combination of physical processes including high river discharge, offshore currents and eddy activity can transport low CO2 coastal water beyond the shelf causing vast areas, tens of thousands of square kilometers, of the open ocean to switch to a CO2 sink for several months. Since anthropogenic-driven climate change is expected to influence ocean circulation patterns, GoM CO2 source-sink characteristics and regional scale ocean carbon budgets may be altered in the future. We also combine

  12. Estimating surface CO2 fluxes from space-borne CO2 dry air mole fraction observations using an ensemble Kalman Filter

    Directory of Open Access Journals (Sweden)

    S. Dance

    2009-04-01

    Full Text Available We have developed an ensemble Kalman Filter (EnKF to estimate 8-day regional surface fluxes of CO2 from space-borne CO2 dry-air mole fraction observations (XCO2 and evaluate the approach using a series of synthetic experiments, in preparation for data from the NASA Orbiting Carbon Observatory (OCO. The 32-day duty cycle of OCO alternates every 16 days between nadir and glint measurements of backscattered solar radiation at short-wave infrared wavelengths. The EnKF uses an ensemble of states to represent the error covariances to estimate 8-day CO2 surface fluxes over 144 geographical regions. We use a 12×8-day lag window, recognising that XCO2 measurements include surface flux information from prior time windows. The observation operator that relates surface CO2 fluxes to atmospheric distributions of XCO2 includes: a the GEOS-Chem transport model that relates surface fluxes to global 3-D distributions of CO2 concentrations, which are sampled at the time and location of OCO measurements that are cloud-free and have aerosol optical depths 2 profiles to XCO2, accounting for differences between nadir and glint measurements, and the associated scene-dependent observation errors. We show that OCO XCO2 measurements significantly reduce the uncertainties of surface CO2 flux estimates. Glint measurements are generally better at constraining ocean CO2 flux estimates. Nadir XCO2 measurements over the terrestrial tropics are sparse throughout the year because of either clouds or smoke. Glint measurements provide the most effective constraint for estimating tropical terrestrial CO2 fluxes by accurately sampling fresh continental outflow over neighbouring oceans. We also present results from sensitivity experiments that investigate how flux estimates change with 1 bias and unbiased errors, 2 alternative duty cycles, 3 measurement density and correlations, 4 the spatial resolution of estimated flux estimates, and 5 reducing the length of the lag window and the

  13. Soil Surface Leak Detection From Carbon Storage Sites Using ∆(CO2:O2) Measurements

    Science.gov (United States)

    Alam, M. M.; Norman, A. L.; Layzell, D. B.

    2015-12-01

    The early detection and remediation of CO2 leaks from Carbon Capture and Storage (CCS) sites is essential for the safety and public support of the technology. A model that integrates gas diffusion, mass flow and biological processes in soils was developed and used to predict the ∆CO2 and ∆O2 concentration differential between the soil surface and the bulk atmosphere under a wide range of environmental conditions that include temperature, soil gas and water content, soil respiratory quotient and rate of O2 uptake, soil porosity and CO2 leakage rate. The results predicted that measurement of ∆(CO2:O2) measurements at the soil surface relative to air should be able to detect a CCS leak as low as 2 µmol/m2/sec. To test this hypothesis, a gas analysis system was designed and constructed. It should allow a series of experiments under controlled conditions to test all aspects of the model. It is hoped that the results from this work will ultimately lead to the development of a new instrument and protocol for the early detection of CO2 leaks from a geological storage sites.

  14. Evaluation of various observing systems for the global monitoring of CO2 surface fluxes

    Directory of Open Access Journals (Sweden)

    A. Klonecki

    2010-08-01

    Full Text Available In the context of raising greenhouse gas concentrations, and the potential feedbacks between climate and the carbon cycle, there is an urgent need to monitor the exchanges of carbon between the atmosphere and both the ocean and the land surfaces. In the so-called top-down approach, the surface fluxes of CO2 are inverted from the observed spatial and temporal concentration gradients. The concentrations of CO2 are measured in-situ at a number of surface stations unevenly distributed over the Earth while several satellite missions may be used to provide a dense and better-distributed set of observations to complement this network. In this paper, we compare the ability of different CO2 concentration observing systems to constrain surface fluxes. The various systems are based on realistic scenarios of sampling and precision for satellite and in-situ measurements. It is shown that satellite measurements based on the differential absorption technique (such as those of SCIAMACHY, GOSAT or OCO provide more information than the thermal infrared observations (such as those of AIRS or IASI. The OCO observations will provide significantly better information than those of GOSAT. A CO2 monitoring mission based on an active (lidar technique could potentially provide an even better constraint. This constraint can also be realized with the very dense surface network that could be built with the same funding as that of the active satellite mission. Despite the large uncertainty reductions on the surface fluxes that may be expected from these various observing systems, these reductions are still insufficient to reach the highly demanding requirements for the monitoring of anthropogenic emissions of CO2 or the oceanic fluxes at a spatial scale smaller than that of oceanic basins. The scientific objective of these observing system should therefore focus on the fluxes linked to vegetation and land ecosystem dynamics.

  15. Low Overpotential and High Current CO2 Reduction with Surface Reconstructed Cu Foam Electrodess

    KAUST Repository

    Min, Shixiong

    2016-06-23

    While recent reports have demonstrated that oxide-derived Cu-based electrodes exhibit high selectivity for CO2 reduction at low overpotential, the low catalytic current density (<2 mA/cm2 at -0.45 V vs. RHE) still largely limits its applications for large-scale fuel synthesis. Here we report an extremely high current density for CO2 reduction at low overpotential using a Cu foam electrode prepared by air-oxidation and subsequent electroreduction. Apart from possessing three-dimensional (3D) open frameworks, the resulting Cu foam electrodes prepared at higher temperatures exhibit enhanced electrochemically active surface area and distinct surface structures. In particular, the Cu foam electrode prepared at 500 °C exhibits an extremely high geometric current density of ~9.4 mA/cm2 in CO2-satrurated 0.1 M KHCO3 aqueous solution and achieving ~39% CO and ~23% HCOOH Faradaic efficiencies at -0.45 V vs. RHE. The high activity and significant selectivity enhancement are attributable to the formation of abundant grain-boundary supported active sites and preferable (100) and (111) facets as a result of reconstruction of Cu surface facets. This work demonstrates that the structural integration of Cu foam with open 3D frameworks and the favorable surface structures is a promising strategy to develop an advanced Cu electrocatalyst that can operate at high current density and low overpotential for CO2 reduction.

  16. Modelling land surface fluxes of CO2 in response to climate change and nitrogen deposition

    DEFF Research Database (Denmark)

    Hansen, Kristina; Ambelas Skjøth, Carsten; Geels, Camilla

    Climate change, land use variations, and impacts of atmospheric nitrogen (N) deposition represent uncertainties for the prediction of future greenhouse gas exchange between land surfaces and the atmosphere as the mechanisms describing nutritional effects are not well developed in climate...... climate feedback mechanisms of CO2 between changes in management, land use practise, and climate change....

  17. Effect of surface-breakdown plasma on metal drilling by pulsed CO2-laser radiation

    Science.gov (United States)

    Arutiunian, P. V.; Baranov, V. Iu.; Bobkov, I. V.; Bol'Shakov, L. A.; Dolgov, V. A.

    1988-03-01

    The effect of low-threshold surface breakdown produced by short (5-microsec) CO2-laser pulses on the metal drilling process is investigated. Data on the interaction of metals with laser pulses having the same duration but different shape are shown to be different. The effect of the ambient atmospheric pressure on the laser drilling process is investigated.

  18. Bayesian belief network for CO2 leak detection by near-surface flux rates for CO2 and perfluorocarbon (PFC) tracer

    Science.gov (United States)

    Yang, Y.; Small, M. J.; Ogretim, E.; Gray, D. D.; Bromhal, G. S.; Strazisar, B. R.; Wells, A. W.

    2010-12-01

    To incorporate the use of multiple geologic sequestration monitoring techniques, a Bayesian Belief Network (BBN) for leak detection inference is applied to integrate the information provided by different techniques deployed at a site. In this study, two monitoring methods, near-surface soil CO2 flux and perfluorocarbon (PFC) tracer concentration, are included in the BBN. First, possible near-surface flux rates for CO2 and PFC tracer as a function of distance from a leakage point are simulated by TOUGH2, given different leakage rates and permeabilities. Then, the natural near-surface CO2 flux and background PFC tracer concentration measured at the Zero Emission Research and Technology (ZERT) site are used to determine critical values for leak inference and to calculate the probabilities of leak detection given a monitoring network. A BBN of leak detection is established by combing the TOUGH2 simulations and the background characterization of near-surface CO2 flux and PFC tracer at the sequestration site. The results show a positive correlation between the detection abilities of PFC tracer and soil CO2 flux, but the PFC tracer is more sensitive for detecting a leak in most cases. The BBN of leak detection including both soil CO2 flux and PFC tracer concentration gives an integrated probability estimation of leak detection for different permeability and leakage rates for a given monitoring network. A BBN developed using the proposed methodology can be used to help site engineers and decision makers to evaluate leakage signals and the risk of undetected leakage, given a suite of monitoring techniques and site conditions.

  19. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface

    NARCIS (Netherlands)

    Trinh, T.T.; Vlugt, T.J.H.; Hägg, M.-B.; Bedeaux, D.; Kjelstrup, S.H.

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of

  20. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface

    NARCIS (Netherlands)

    Trinh, T.T.; Vlugt, T.J.H.; Hägg, M.-B.; Bedeaux, D.; Kjelstrup, S.H.

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of t

  1. Deriving a sea surface climatology of CO2 fugacity in support of air–sea gas flux studies

    Directory of Open Access Journals (Sweden)

    L. M. Goddijn-Murphy

    2014-07-01

    Full Text Available Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean Carbon Dioxide (CO2 Atlas (SOCAT has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. fCO2 is highly sensitive to temperature and the measurements are only valid for the instantaneous sea surface temperature (SST that is measured concurrent with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air–sea CO2 fluxes it is therefore desirable to calculate fCO2 valid for climate quality SST. This paper presents a method for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using climate quality SST data from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010. The partial pressure of CO2 (pCO2 is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air–sea CO2 flux, and hence the presented fCO2 distributions can be used in air–sea gas flux calculations together with climatologies of other climate variables.

  2. Elevated soil CO2 efflux at the boundaries between impervious surfaces and urban greenspaces

    Science.gov (United States)

    Wu, XiaoGang; Hu, Dan; Ma, ShengLi; Zhang, Xia; Guo, Zhen; Gaston, Kevin J.

    2016-09-01

    Impervious surfaces and greenspaces have significant impacts on ecological processes and ecosystem services in urban areas. However, there have been no systematic studies of how the interaction between the two forms of land cover, and especially their edge effects, influence ecosystem properties. This has made it difficult to evaluate the effectiveness of urban greenspace design in meeting environmental goals. In this study, we investigated edge effects on soil carbon dioxide (CO2) fluxes in Beijing and found that soil CO2 flux rates were averagely 73% higher 10 cm inwards from the edge of greenspaces. Distance, soil temperature, moisture, and their interaction significantly influenced soil CO2 flux rates. The magnitude and distance of edge effects differed among impervious structure types. Current greening policy and design should be adjusted to avoid the carbon sequestration service of greenspaces being limited by their fragmentation.

  3. Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

    Science.gov (United States)

    Krevor, Samuel; Benson, Sally; Rella, Chris; Perrin, Jean-Christophe; Esposito, Ariel; Crosson, Eric

    2010-05-01

    The surface monitoring of CO2 over geologic sequestration sites will be an essential tool in the monitoring and verification of sequestration projects. Surface monitoring is the only tool that currently provides the opportunity to detect and quantify leakages on the order of 1000 tons/year CO2. Near-surface detection and quantification can be made complicated, however, due to large temporal and spatial variations in natural background CO2 fluxes from biological processes. In addition, current surface monitoring technologies, such as the use of IR spectroscopy in eddy covariance towers and aerial surveys, radioactive or noble gas isotopic tracers, and flux chamber gas measurements can generally accomplish one or two of the necessary tasks of leak detection, identification, and quantification, at both large spatial scales and high spatial resolution. It would be useful, however, to combine the utility of these technologies so that a much simplified surface monitoring program can be deployed. Carbon isotopes of CO2 provide an opportunity to distinguish between natural biogenic CO2 fluxes from the ground and CO2 leaking from a sequestration reservoir that has ultimate origins in a process giving it a distinct isotopic signature such as natural gas processing. Until recently, measuring isotopic compositions of gases was a time-consuming and expensive process utilizing mass-spectrometry, not practical for deployment in a high-resolution survey of a potential leakage site at the surface. Recent developments in commercially available instruments utilizing wavelength scanned cavity ringdown spectroscopy (WS-CRDS) and Fourier transform infrared spectroscopy (FT-IR) have made it possible to rapidly measure the isotopic composition of gases including the 13C and 12C isotopic composition of CO2 in a field setting. A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to rapidly detect and

  4. Boron-doped diamond semiconductor electrodes: Efficient photoelectrochemical CO2 reduction through surface modification

    Science.gov (United States)

    Roy, Nitish; Hirano, Yuiri; Kuriyama, Haruo; Sudhagar, Pitchaimuthu; Suzuki, Norihiro; Katsumata, Ken-Ichi; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Serizawa, Izumi; Takayama, Tomoaki; Kudo, Akihiko; Fujishima, Akira; Terashima, Chiaki

    2016-11-01

    Competitive hydrogen evolution and multiple proton-coupled electron transfer reactions limit photoelectrochemical CO2 reduction in aqueous electrolyte. Here, oxygen-terminated lightly boron-doped diamond (BDDL) thin films were synthesized as a semiconductor electron source to accelerate CO2 reduction. However, BDDL alone could not stabilize the intermediates of CO2 reduction, yielding a negligible amount of reduction products. Silver nanoparticles were then deposited on BDDL because of their selective electrochemical CO2 reduction ability. Excellent selectivity (estimated CO:H2 mass ratio of 318:1) and recyclability (stable for five cycles of 3 h each) for photoelectrochemical CO2 reduction were obtained for the optimum silver nanoparticle-modified BDDL electrode at -1.1 V vs. RHE under 222-nm irradiation. The high efficiency and stability of this catalyst are ascribed to the in situ photoactivation of the BDDL surface during the photoelectrochemical reaction. The present work reveals the potential of BDDL as a high-energy electron source for use with co-catalysts in photochemical conversion.

  5. Correlations of surface ocean pCO2 to satellite chlorophyll on monthly to interannual timescales

    Science.gov (United States)

    Fay, Amanda R.; McKinley, Galen A.

    2017-03-01

    On the mean, ocean carbon uptake is linked to biological productivity, but how biological variability impacts carbon uptake is poorly quantified. Our ability to diagnose past change, understand present variability, and predict the future state of the global carbon cycle requires improving mechanistic understanding in this area. Here we make use of colocated pCO2 and temperature data, a merged surface ocean color product, and physical fields from an ocean state estimate to assess relationships between surface ocean biology and the carbon cycle on seasonal, monthly anomaly, and interannual timescales over the period 1998-2014. Using a correlation analysis on spatial scales from local to basin-scale biomes, we identify the timescales on which ocean productivity could be directly modifying ocean carbon uptake. On seasonal timescales outside of the equatorial Pacific, biome-scale correlations are negative between chlorophyll and pCO2. Though this relationship is pervasive, the underlying mechanisms vary across timescales and biomes. Consistent with previous findings, biological activity is a significant driver of pCO2 seasonality only in the subpolar biomes. For monthly anomalies acting on top of the mean seasonality, productivity and pCO2 changes are significantly correlated in the subpolar North Pacific and Southern Ocean. Only in the Southern Ocean are correlations consistent with a dominant role for biology in the surface ocean carbon cycle on all timescales.

  6. Observational determination of surface radiative forcing by CO2 from 2000 to 2010

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, Daniel R.; Collins, William D.; Gero, P. Johnathan; Torn, Margaret S.; Mlawer, Eli J.; Shippert, Timothy R.

    2015-02-25

    The climatic impact of CO2 and other greenhouse gases is usually quantified in terms of radiative forcing1, calculated as the difference between estimates of the Earth’s radiation field from pre-industrial and present-day concentrations of these gases. Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annual-mean radiative forcing at the tropopause of 1.82 ± 0.19 W m-2 (ref. 2). However, despite widespread scientific discussion and modelling of the climate impacts of well-mixed greenhouse gases, there is little direct observational evidence of the radiative impact of increasing atmospheric CO2. Here we present observationally based evidence of clear-sky CO2 surface radiative forcing that is directly attributable to the increase, between 2000 and 2010, of 22 parts per million atmospheric CO2. The time series of this forcing at the two locations—the Southern Great Plains and the North Slope of Alaska—are derived from Atmospheric Emitted Radiance Interferometer spectra3 together with ancillary measurements and thoroughly corroborated radiative transfer calculations4. The time series both show statistically significant trends of 0.2 W m-2 per decade (with respective uncertainties of ±0.06 W m-2 per decade and ±0.07 W m-2 per decade) and have seasonal ranges of 0.1–0.2 W m-2. This is approximately ten per cent of the trend in downwelling longwave radiation5, 6, 7. These results confirm theoretical predictions of the atmospheric greenhouse effect due to anthropogenic emissions, and provide empirical evidence of how rising CO2 levels, mediated by temporal variations due to photosynthesis and respiration, are affecting the surface energy balance.

  7. CO2 laser surface treatment of failed dental implants for re-implantation: an animal study.

    Science.gov (United States)

    Kasraei, Shahin; Torkzaban, Parviz; Shams, Bahar; Hosseinipanah, Seyed Mohammad; Farhadian, Maryam

    2016-07-01

    The aim of the present study was to evaluate the success rate of failed implants re-implanted after surface treatment with CO2 laser. Despite the widespread use of dental implants, there are many incidents of failures. It is believed that lasers can be applied to decontaminate the implant surface without damaging the implant. Ten dental implants that had failed for various reasons other than fracture or surface abrasion were subjected to CO2 laser surface treatment and randomly placed in the maxillae of dogs. Three failed implants were also placed as the negative controls after irrigation with saline solution without laser surface treatment. The stability of the implants was evaluated by the use of the Periotest values (PTVs) on the first day after surgery and at 1, 3, and 6 months post-operatively. The mean PTVs of treated implants increased at the first month interval, indicating a decrease in implant stability due to inflammation followed by healing of the tissue. At 3 and 6 months, the mean PTVs decreased compared to the 1-month interval (P implant stability. The mean PTVs increased in the negative control group compared to baseline (P implants were significantly lower than control group at 3 and 6 months after implant placement (P implantation of failed implants in Jack Russell Terrier dogs after CO2 laser surface debridement is associated with a high success rate in terms of implant stability.

  8. Martian CO2 icy surface mysterious evolution with insolation during spring and summer season

    Science.gov (United States)

    Pilorget, C.; Douté, S.; Vincendon, M.

    2016-12-01

    On Mars, the evolution of the CO2 reservoirs is one of the key aspects to decipher the climate changes. During winter, up to 30% of the atmosphere (composed of 95% of CO2) condenses at the surface to form seasonal polar caps, which completely sublime in spring, except in the South where a residual cap persists during summer. During spring and summer, the CO2 ice caps exhibit a mysterious evolution of their apparent albedo that looks correlated with the insolation. These radiative properties are, however, challenging to retrieve precisely on Mars, mostly because of the presence of aerosols in the atmosphere. Here we use both HiRISE/MRO high resolution images and CRISM/MRO VIS-NIR multi-angular hyperspectral data from the South residual cap (6 regions), corrected from the aerosol contribution, to investigate this mysterious behavior and determine the energy budget of the icy surface through the retrieval of the directional-hemispheric albedo. In particular, CRISM multi-angular dataset enables to determine the BRDF of the surface, decoupled from the aerosol contribution, which also brings new constrains on the ice structure. Both HiRISE and CRISM data show a continuous increase of the nadir reflectance factor of the icy surface until Ls270, followed by a decrease during the summer season, at both local and regional scale. Different classes of surface spectro-photometric behaviors are observed, the variations being likely linked to the composition, grain micro-texture and surface roughness of polar materials. In particular, the directional-hemispheric albedo calculated at 750 nm is typically 10-15% higher than the reflectance factor measured at nadir and exhibits similar seasonal behavior. In the meantime ice cracking is observed in HiRISE images after Ls270, thus without being correlated with the albedo increase. We will discuss these results and their implications for the characterization of the CO2 icy surfaces of Mars and their seasonal evolution.

  9. VARIABILITY OF ATMOSPHERIC CO2 OVER INDIA AND SURROUNDING OCEANS AND CONTROL BY SURFACE FLUXES

    Directory of Open Access Journals (Sweden)

    R. K. Nayak

    2012-08-01

    Full Text Available In the present study, seasonal and inter-annual variability of atmospheric CO2 concentration over India and surrounding oceans during 2002–2010 derived from Atmospheric InfrarRed Sounder observation and their relation with the natural flux exchanges over terrestrial Indian and surrounding oceans were analyzed. The natural fluxes over the terrestrial Indian in the form of net primary productivity (NPP were simulated based on a terrestrial biosphere model governed by time varying climate parameters (solar radiation, air temperature, precipitation etc and satellite greenness index together with the land use land cover and soil attribute maps. The flux exchanges over the oceans around India (Tropical Indian Ocean: TIO were calculated based on a empirical model of CO2 gas dissolution in the oceanic water governed by time varying upper ocean parameters such as gradient of partial pressure of CO2 between ocean and atmosphere, winds, sea surface temperature and salinity. Comparison between the variability of atmospheric CO2 anomaly with the anomaly of surface fluxes over India and surrounding oceans suggests that biosphere uptake over India and oceanic uptake over the south Indian Ocean could play positive role on the control of seasonal variability of atmospheric carbon dioxide growth rate. On inter-annual scale, flux exchanges over the tropical north Indian Ocean could play positive role on the control of atmospheric carbon dioxide growth rate.

  10. A Controlled Field Pilot for Testing Near Surface CO2 Detection Techniques and Transport Models

    Science.gov (United States)

    Spangler, L. H.; Dobeck, L.

    2007-12-01

    A field facility has been developed to allow controlled studies of near surface CO2transport and detection technologies. The key component of the facility is a shallow horizontal, well slotted over 70m of its length and divided into seven zones via packers with mass flow control in each individual zone. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects and those design parameters will be discussed. A wide variety of detection techniques were deployed by collaborators from Los Alamos National Lab, Lawrence Berkeley National Lab, the National Energy Technology Lab, Pacific Northwest National Lab, Lawrence Livermore National Lab and West Virginia University. Techniques included eddy covariance, soil gas measurements, hyperspectral imaging for plant stress detection, differential absorption LIDAR (both free space atmospheric and below surface soil gas), tracer studies, water sampling, stable isotope studies, and soil flux chambers. An overview of these results will be presented.

  11. CO2FieldLab project. Near-surface downhole electrical resistivity monitoring for CO2 shallow injection at the Svelvik ridge (Norway).

    Science.gov (United States)

    Denchik, N.; Pezard, P.; Paris, J.; Geeraert, M.; Henry, G.; Baqué, L.; Barry, S.; Neyens, D.

    2012-04-01

    The CO2FieldLab shallow injection experiment is a collaborative effort aimed at developing, verifying, and evaluating near-surface monitoring techniques for geological sequestration of CO2. The objective is to create a downhole leakage of CO2 in order to demonstrate whether existing monitoring techniques have the ability to detect and quantify the CO2 loss. The CO2FieldLab project associates collaboration from several research groups and organizations (SINTEF, NGI, BRGM, BGS, CNRS, imaGeau and Schlumberger). For this, the field Laboratory for monitoring CO2 migration and leakage was established in Holocene deposits of the Svelvik ridge, located in the Drammensfjord 50 km south of Oslo (Norway). It is a glaciofluvial-glaciomarine terminal deposit formed during the last deglaciation. The depth to the bedrock is located between 300 and 400 m. The central part of the ridge is aerially exposed up to 70 m above sea level, constituting a phreatic aquifer. The characterization phase and associated modelling suggest that the site is suitable for studying both gas migration and leakage at shallow depths. The shallow aquifer (down to 50 m) consists in a relatively homogeneous sand body with a depositional dip of about 10° to the North. The shallow injection experiment took place in September of 2011 and consisted in an injection of CO2 at a depth of 20 m from a 45° inclined well. The purpose of this phase was to simulate a point source leakage, which could possibly occur due to failure of a deep well completion. A total mass of 1.67 ton of CO2 was injected over a period of 6 days. The water table was located at 60 cm depth during the experiment and a transition from fresh to salt pore water was found below 12 m depth. An integrated set of surface and downhole strategies was deployed across a 64 m2 square monitoring area: cross-hole radar, water and gas phases physico-chemical parameters (BRGM); multi-hole electrical ALERT system (BGS), CO2 concentration in soils and gas

  12. Pulsed CO2 laser interaction with a metal surface at oblique incidence

    Science.gov (United States)

    McKay, J. A.; Schriempf, J. T.; Cronburg, T. L.; Eninger, J. E.; Woodroffe, J. A.

    1980-01-01

    Thermal fluence deposition and surface pressure generation produced by a CO2 laser pulse have been measured as a function of angle of incidence theta on sheet aluminum in air. The paper finds that air plasma ignition depends on the laser beam intensity I sub 0 only, not on the surface-normal flux (I sub 0)(cos theta). Conversely, the fluence deposition and surface pressure depend only on the product (I sub 0)(cos theta), and obey the square-root and two-thirds-power dependences observed with simple I sub 0 variation at normal incidence.

  13. A New Source of CO2 in the Universe: A Photoactivated Eley-Rideal Surface Reaction on Water Ices

    Science.gov (United States)

    Yuan, Chunqing; Cooke, Ilsa R.; Yates, John T., Jr.

    2014-08-01

    CO2 is one of the most abundant components of ices in the interstellar medium; however, its formation mechanism has not been clearly identified. Here we report an experimental observation of an Eley-Rideal-type reaction on a water ice surface, where CO gas molecules react by direct collisions with surface OH radicals, made by photodissociation of H2O molecules, to produce CO2 ice on the surface. The discovery of this source of CO2 provides a new mechanism to explain the high relative abundance of CO2 ice in space.

  14. Experimental and theoretical analysis of defocused CO2 laser microchanneling on PMMA for enhanced surface finish

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2017-02-01

    The poor surface finish of CO2 laser-micromachined microchannel walls is a major limitation of its utilization despite several key advantages, like low fabrication cost and low time consumption. Defocused CO2 laser beam machining is an effective solution for fabricating smooth microchannel walls on polymer and glass substrates. In this research work, the CO2 laser microchanneling process on PMMA has been analyzed at different beam defocus positions. Defocused processing has been investigated both theoretically and experimentally, and the depth of focus and beam diameter have been determined experimentally. The effect of beam defocusing on the microchannel width, depth, surface roughness, heat affected zone and microchannel profile were examined. A previously developed analytical model for microchannel depth prediction has been improved by incorporating the threshold energy density factor. A semi-analytical model for predicting the microchannel width at different defocus positions has been developed. A semi-empirical model has also been developed for predicting microchannel widths at different defocusing conditions for lower depth values. The developed models were compared and verified by performing actual experiments. Multi-objective optimization was performed to select the best optimum set of input parameters for achieving the desired surface roughness.

  15. CO2 adsorption-assisted CH4 desorption on carbon models of coal surface: A DFT study

    Science.gov (United States)

    Xu, He; Chu, Wei; Huang, Xia; Sun, Wenjing; Jiang, Chengfa; Liu, Zhongqing

    2016-07-01

    Injection of CO2 into coal is known to improve the yields of coal-bed methane gas. However, the technology of CO2 injection-enhanced coal-bed methane (CO2-ECBM) recovery is still in its infancy with an unclear mechanism. Density functional theory (DFT) calculations were performed to elucidate the mechanism of CO2 adsorption-assisted CH4 desorption (AAD). To simulate coal surfaces, different six-ring aromatic clusters (2 × 2, 3 × 3, 4 × 4, 5 × 5, 6 × 6, and 7 × 7) were used as simplified graphene (Gr) carbon models. The adsorption and desorption of CH4 and/or CO2 on these carbon models were assessed. The results showed that a six-ring aromatic cluster model (4 × 4) can simulate the coal surface with limited approximation. The adsorption of CO2 onto these carbon models was more stable than that in the case of CH4. Further, the adsorption energies of single CH4 and CO2 in the more stable site were -15.58 and -18.16 kJ/mol, respectively. When two molecules (CO2 and CH4) interact with the surface, CO2 compels CH4 to adsorb onto the less stable site, with a resulting significant decrease in the adsorption energy of CH4 onto the surface of the carbon model with pre-adsorbed CO2. The Mulliken charges and electrostatic potentials of CH4 and CO2 adsorbed onto the surface of the carbon model were compared to determine their respective adsorption activities and changes. At the molecular level, our results showed that the adsorption of the injected CO2 promoted the desorption of CH4, the underlying mechanism of CO2-ECBM.

  16. CO2-Brine-Iron-bearing Clay Mineral Interactions: Surface Area Changes and Fracture-Filling Potentials in Geologic CO2 Sequestration

    Science.gov (United States)

    Jun, Y.; Hu, Y.

    2011-12-01

    Geologic carbon dioxide sequestration (GCS) is a promising option to reduce anthropogenic CO2 emission from coal-fired power plants. The injected CO2 in GCS sites can induce dissolution of rocks and secondary mineral formation, potentially change the physical properties of the geological formations, and thus influence the transport and injectivity of CO2. However, most of the relevant studies are based on hydrological transport, using simulation models rather than studying actual interfacial chemical reactions. The mechanisms and kinetics of interfacial reactions among supercritical CO2 (scCO2)-saline water-rock surfaces at the molecular scale and their impacts on CO2 leakage have not been well understood. This research investigated the effects of various environmental factors (such as temperature, pressure, salinity, and different metal ion and organic-containing brine) on the dissolution and surface morphological changes of clay minerals. In this work, iron-bearing clay mineral, biotite [K(Mg,Fe)3AlSi3O10(OH,F)2], was used for model clay minerals in potential GCS sites. Both fluid/solid chemistry analysis and interfacial topographic studies were conducted to investigate the dissolution/precipitation on clay mineral surfaces under GCS conditions in high salinity systems. Using atomic force microscopy (AFM) and scanning electron microscopy (SEM), the interfacial surface morphology changes were observed. Shortly after a CO2 pressure of 102 atm is applied at 95oC, in situ pH of solutions was 3.15 ± 0.10. The early intrinsic dissolution rates of biotite were 8.4 ± 2.8 × 10-13 and 11.2 ± 3.0 × 10-13 mol Si m-2s-1 in water and NaCl solution, respectively. At the early stage of reaction, fast growth of fibrous illite on biotite basal planes was observed. After 22-70 h reaction, the biotite basal surface cracked, resulting in illite detaching from the surfaced. Later, the cracked surface layer was released into solution, thus the inner layer was exposed as a renewed

  17. Irradiation effects of CO2 laser parameters on surface morphology of fused silica

    Institute of Scientific and Technical Information of China (English)

    Xiang Xia; Zheng Wan-Guo; Yuan Xiao-Dong; Dai Wei; Juang Yong; Li Xi-Bin; Wang Hai-Jun; Lü Hai-Bing; Zu Xiao-Tao

    2011-01-01

    To understand the surface morphology evolution of fused silica induced by 10.6-prn CO2 laser irradiation atdifferent parameters, this paper reports that optical microscopy, profilometry, and hydrophilicity tests are utilized to characterize the surface structure and roughness of the laser irradiated area. The results show that three typical surface morphologies and two typical by drophilicity test images are observed at different laser powers and pulse durations. Thecorrelations between surface temperature and surface morphology as well as hydrophilicity behaviours are presented.The different hydrophilicity behaviours are related to surface structures of the laser-induced crater and thermal diffusion area. The thermal diffusion length monotonously increases with increasing laser power and pulse duration. The crater width is almost determined by the laser beam size. The crater depth is more sensitive to the laser power and pulse duration than the crater width.

  18. Correlation between Surface Roughness Characteristics in CO2 Laser Cutting of Mild Steel

    Directory of Open Access Journals (Sweden)

    M. Radovanović

    2012-12-01

    Full Text Available CO2 laser oxygen cutting of mild steel is widely used industrial application. Cut surface quality is a very important characteristic of laser cutting that ensures an advantage over other contour cutting processes. In this paper mathematical models for estimating characteristics of surface quality such as average surface roughness and ten-point mean roughness in CO2 laser cutting of mild steel based on laser cutting parameters were developed. Empirical models were developed using artificial neural networks and experimental data collected. Taguchi’s orthogonal array was implemented for experimental plan. From the analysis of the developed mathematical models it was observed that functional dependence between laser cutting parameters, their interactions and surface roughness characteristics is complex and non-linear. It was also observed that there exist region of minimal average surface roughness to ten-point mean roughness ratio. The relationship between average surface roughness and ten-point mean roughness was found to be nonlinear and can be expressed with a second degree polynomial.

  19. Optimization of CO2 Laser Cutting Process using Taguchi and Dual Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    M. Madić

    2014-09-01

    Full Text Available Selection of optimal cutting parameter settings for obtaining high cut quality in CO2 laser cutting process is of great importance. Among various analytical and experimental optimization methods, the application of Taguchi and response surface methodology is one of most commonly used for laser cutting process optimization. Although the concept of dual response surface methodology for process optimization has been used with success, till date, no experimental study has been reported in the field of laser cutting. In this paper an approach for optimization of CO2 laser cutting process using Taguchi and dual response surface methodology is presented. The goal was to determine the near optimal laser cutting parameter values in order to ensure robust condition for minimization of average surface roughness. To obtain experimental database for development of response surface models, Taguchi’s L25 orthogonal array was implemented for experimental plan. Three cutting parameters, the cutting speed (3, 4, 5, 6, 7 m/min, the laser power (0.7, 0.9, 1.1, 1.3, 1.5 kW, and the assist gas pressure (3, 4, 5, 6, 7 bar, were used in the experiment. To obtain near optimal cutting parameters settings, multi-stage Monte Carlo simulation procedure was performed on the developed response surface models.

  20. A multi-decade record of high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

    Science.gov (United States)

    Bakker, Dorothee; Landa, Camilla S.; Pfeil, Benjamin; Metzl, Nicolas; O’Brien, Kevin; Olsen, Are; Smith, Karl; Cosca, Cathy; Harasawa, Sumiko; Nakaoka, Shin-ichiro; Jones, Stephen; Nojiri, Yukihiro; Steinhoff, Tobias; Sweeney, Colm; Schuster, Ute; Takahashi, Taro; Tilbrook, Bronte; Wada, Chisato; Wanninkhof, Rik; Alin, Simone R.; Balestrini, Carlos F.; Barbero, Leticia; Bates, Nicholas; Bianchi, Alejandro A.; Bonou, Frédéric; Boutin, Jacqueline; Bozec, Yann; Burger, Eugene F.; Cai, Wei-Jun; Castle, Robert D.; Chen, Liqi; Chierici, Melissa; Currie, Kim; Evans, Wiley; Featherstone, Charles; Feely, Richard; Fransson, Agneta; Goyet, Catherine; Greenwood, Naomi; Gregor, Luke; Hankin, Steven; Hardman-Mountford, Nick J.; Harlay, Jérôme; Hauck, Judith; Hoppema, Mario; Humphreys, Matthew P.; Hunt, Christopher W.; Huss, Betty; Ibánhez, J. Severino P.; Keeling, Ralph F.; Johannessen, Truls; Kitidis, Vassilis; Körtzinger, Arne; Kozyr, Alex; Krasakopoulou, Evangelia; Kuwata, Akira; Landschützer, Peter; Lauvset, Siv K.; Lefèvre, Nathalie; Lo Monaco, Claire; Manke, Ansley; Mathis, Jeremy T.; Merlivat, Liliane; Millero, Frank J.; Monteiro, Pedro M. S.; Munro, David R.; Murata, Akihiko; Newberger, Timothy; Omar, Abdirahman M.; Ono, Tsuneo; Paterson, Kristina; Pearce, David; Pierrot, Denis; Robbins, Lisa L.; Saito, Shu; Salisbury, Joe; Schlitzer, Reiner; Schneider, Bernd; Schweitzer, Roland; Sieger, Rainer; Skjelvan, Ingunn; Sullivan, Kevin F.; Sutherland, Stewart C.; Sutton, Adrienne J.; Tadokoro, Kazuaki; Telszewski, Maciej; Tuma, Matthias; van Heuven, Steven M. A. C.; Vandemark, Douglas; Ward, Brian; Watson, Andrew J.; Xu, Suqing

    2016-01-01

    The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled f CO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million f CO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million f CO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water f CO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water f CO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). 

  1. A multi-decade record of high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

    Science.gov (United States)

    Bakker, Dorothee C. E.; Pfeil, Benjamin; Landa, Camilla S.; Metzl, Nicolas; O'Brien, Kevin M.; Olsen, Are; Smith, Karl; Cosca, Cathy; Harasawa, Sumiko; Jones, Stephen D.; Nakaoka, Shin-ichiro; Nojiri, Yukihiro; Schuster, Ute; Steinhoff, Tobias; Sweeney, Colm; Takahashi, Taro; Tilbrook, Bronte; Wada, Chisato; Wanninkhof, Rik; Alin, Simone R.; Balestrini, Carlos F.; Barbero, Leticia; Bates, Nicholas R.; Bianchi, Alejandro A.; Bonou, Frédéric; Boutin, Jacqueline; Bozec, Yann; Burger, Eugene F.; Cai, Wei-Jun; Castle, Robert D.; Chen, Liqi; Chierici, Melissa; Currie, Kim; Evans, Wiley; Featherstone, Charles; Feely, Richard A.; Fransson, Agneta; Goyet, Catherine; Greenwood, Naomi; Gregor, Luke; Hankin, Steven; Hardman-Mountford, Nick J.; Harlay, Jérôme; Hauck, Judith; Hoppema, Mario; Humphreys, Matthew P.; Hunt, Christopher W.; Huss, Betty; Ibánhez, J. Severino P.; Johannessen, Truls; Keeling, Ralph; Kitidis, Vassilis; Körtzinger, Arne; Kozyr, Alex; Krasakopoulou, Evangelia; Kuwata, Akira; Landschützer, Peter; Lauvset, Siv K.; Lefèvre, Nathalie; Lo Monaco, Claire; Manke, Ansley; Mathis, Jeremy T.; Merlivat, Liliane; Millero, Frank J.; Monteiro, Pedro M. S.; Munro, David R.; Murata, Akihiko; Newberger, Timothy; Omar, Abdirahman M.; Ono, Tsuneo; Paterson, Kristina; Pearce, David; Pierrot, Denis; Robbins, Lisa L.; Saito, Shu; Salisbury, Joe; Schlitzer, Reiner; Schneider, Bernd; Schweitzer, Roland; Sieger, Rainer; Skjelvan, Ingunn; Sullivan, Kevin F.; Sutherland, Stewart C.; Sutton, Adrienne J.; Tadokoro, Kazuaki; Telszewski, Maciej; Tuma, Matthias; van Heuven, Steven M. A. C.; Vandemark, Doug; Ward, Brian; Watson, Andrew J.; Xu, Suqing

    2016-09-01

    The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) "living data" publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual

  2. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    Science.gov (United States)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  3. Leakage and Sepage of CO2 from Geologic Carbon SequestrationSites: CO2 Migration into Surface Water

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curt M.; Lewicki, Jennifer L.

    2005-06-17

    Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO{sub 2}) and its storage in deep geologic formations. One of the concerns of geologic carbon sequestration is that injected CO{sub 2} may leak out of the intended storage formation, migrate to the near-surface environment, and seep out of the ground or into surface water. In this research, we investigate the process of CO{sub 2} leakage and seepage into saturated sediments and overlying surface water bodies such as rivers, lakes, wetlands, and continental shelf marine environments. Natural CO{sub 2} and CH{sub 4} fluxes are well studied and provide insight into the expected transport mechanisms and fate of seepage fluxes of similar magnitude. Also, natural CO{sub 2} and CH{sub 4} fluxes are pervasive in surface water environments at levels that may mask low-level carbon sequestration leakage and seepage. Extreme examples are the well known volcanic lakes in Cameroon where lake water supersaturated with respect to CO{sub 2} overturned and degassed with lethal effects. Standard bubble formation and hydrostatics are applicable to CO{sub 2} bubbles in surface water. Bubble-rise velocity in surface water is a function of bubble size and reaches a maximum of approximately 30 cm s{sup -1} at a bubble radius of 0.7 mm. Bubble rise in saturated porous media below surface water is affected by surface tension and buoyancy forces, along with the solid matrix pore structure. For medium and fine grain sizes, surface tension forces dominate and gas transport tends to occur as channel flow rather than bubble flow. For coarse porous media such as gravels and coarse sand, buoyancy dominates and the maximum bubble rise velocity is predicted to be approximately 18 cm s{sup -1}. Liquid CO{sub 2} bubbles rise slower in water than gaseous CO{sub 2} bubbles due to the smaller density contrast. A comparison of ebullition (i.e., bubble formation) and resulting bubble flow versus dispersive gas transport for CO

  4. Leakage and Sepage of CO2 from Geologic Carbon SequestrationSites: CO2 Migration into Surface Water

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curt M.; Lewicki, Jennifer L.

    2005-06-17

    Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO{sub 2}) and its storage in deep geologic formations. One of the concerns of geologic carbon sequestration is that injected CO{sub 2} may leak out of the intended storage formation, migrate to the near-surface environment, and seep out of the ground or into surface water. In this research, we investigate the process of CO{sub 2} leakage and seepage into saturated sediments and overlying surface water bodies such as rivers, lakes, wetlands, and continental shelf marine environments. Natural CO{sub 2} and CH{sub 4} fluxes are well studied and provide insight into the expected transport mechanisms and fate of seepage fluxes of similar magnitude. Also, natural CO{sub 2} and CH{sub 4} fluxes are pervasive in surface water environments at levels that may mask low-level carbon sequestration leakage and seepage. Extreme examples are the well known volcanic lakes in Cameroon where lake water supersaturated with respect to CO{sub 2} overturned and degassed with lethal effects. Standard bubble formation and hydrostatics are applicable to CO{sub 2} bubbles in surface water. Bubble-rise velocity in surface water is a function of bubble size and reaches a maximum of approximately 30 cm s{sup -1} at a bubble radius of 0.7 mm. Bubble rise in saturated porous media below surface water is affected by surface tension and buoyancy forces, along with the solid matrix pore structure. For medium and fine grain sizes, surface tension forces dominate and gas transport tends to occur as channel flow rather than bubble flow. For coarse porous media such as gravels and coarse sand, buoyancy dominates and the maximum bubble rise velocity is predicted to be approximately 18 cm s{sup -1}. Liquid CO{sub 2} bubbles rise slower in water than gaseous CO{sub 2} bubbles due to the smaller density contrast. A comparison of ebullition (i.e., bubble formation) and resulting bubble flow versus dispersive gas transport for CO

  5. Global climate impacts of bioenergy from forests: implications from biogenic CO2 fluxes and surface albedo

    Science.gov (United States)

    Cherubini, Francesco; Bright, Ryan; Strømman, Anders

    2013-04-01

    Production of biomass for bioenergy can alter biogeochemical and biogeophysical mechanisms, thus affecting local and global climate. Recent scientific developments mainly embraced impacts from land use changes resulting from area-expanded biomass production, with several extensive insights available. Comparably less attention, however, is given to the assessment of direct land surface-atmosphere climate impacts of bioenergy systems under rotation such as in plantations and forested ecosystems, whereby land use disturbances are only temporary. In this work, we assess bioenergy systems representative of various biomass species (spruce, pine, aspen, etc.) and climatic regions (US, Canada, Norway, etc.), for both stationary and vehicle applications. In addition to conventional greenhouse gas (GHG) emissions through life cycle activities (harvest, transport, processing, etc.), we evaluate the contributions to global warming of temporary effects resulting from the perturbation in atmospheric carbon dioxide (CO2) concentration caused by the timing of biogenic CO2 fluxes and in surface reflectivity (albedo). Biogenic CO2 fluxes on site after harvest are directly measured through Net Ecosystem Productivity (NEP) chronosequences from flux towers established at the interface between the forest canopy and the atmosphere and are inclusive of all CO2 exchanges occurring in the forest (e.g., sequestration of CO2 in growing trees, emissions from soil respiration and decomposition of dead organic materials). These primary data based on empirical measurements provide an accurate representation of the forest carbon sink behavior over time, and they are used in the elaboration of high-resolution IRFs for biogenic CO2 emissions. Chronosequence of albedo values from clear-cut to pre-harvest levels are gathered from satellite data (MODIS black-sky shortwave broadband, Collection 5, MCD43A). Following the cause-effect chain from emissions to damages, through radiative forcing and changes

  6. AN ARTIFICIAL INTELLIGENCE APPROACH FOR THE PREDICTION OF SURFACE ROUGHNESS IN CO2 LASER CUTTING

    Directory of Open Access Journals (Sweden)

    MILOŠ MADIĆ

    2012-12-01

    Full Text Available In laser cutting, the cut quality is of great importance. Multiple non-linear effects of process parameters and their interactions make very difficult to predict cut quality. In this paper, artificial intelligence (AI approach was applied to predict the surface roughness in CO2 laser cutting. To this aim, artificial neural network (ANN model of surface roughness was developed in terms of cutting speed, laser power and assist gas pressure. The experimental results obtained from Taguchi’s L25 orthogonal array were used to develop ANN model. The ANN mathematical model of surface roughness was expressed as explicit nonlinear function of the selected input parameters. Statistical results indicate that the ANN model can predict the surface roughness with good accuracy. It was showed that ANNs may be used as a good alternative in analyzing the effects of cutting parameters on the surface roughness.

  7. A model study of the seasonal and long term North Atlantic surface pCO2 variability

    Directory of Open Access Journals (Sweden)

    C. Heinze

    2011-10-01

    Full Text Available A coupled biogeochemical-physical ocean model is used to study the long term variations of surface pCO2 in the North Atlantic Ocean. The model agrees well with recent underway pCO2 observations from the Surface Ocean CO2 Atlas (SOCAT database in various locations in the North Atlantic. The distinct seasonal cycles observed at different parts of the North Atlantic are well reproduced by the model. In most regions except the subpolar domain, the recent observed trends in pCO2 and air–sea carbon fluxes are also simulated by the model. Over a long period between 1960–2008, the primary mode of surface pCO2 variability is dominated by the increasing trend associated with the invasion of anthropogenic CO2 into the ocean. We show that, to first order, the ocean surface circulation and air–sea heat flux patterns can explain the spatial variability of this dominant increasing trend. Regions with strong surface mass transport and negative air–sea heat flux have the tendency to maintain lower surface pCO2. Regions of surface convergence and mean positive air–sea heat flux such as the subtropical gyre and the western subpolar gyre have faster increase in pCO2 over a long term period. The North Atlantic Oscillation (NAO plays a major role in controlling the variability occurring at interannual to decadal time scales. The NAO predominantly influences surface pCO2 in the North Atlantic by changing the physical properties of the North Atlantic water masses, particularly by perturbing the temperature and dissolved inorganic carbon in the surface ocean. We show that present underway observations are valuable for both calibrating the model, as well as for improving our understanding of the regionally heterogeneous variability of surface pCO2. In addition, they can be important for detecting any long term change in the regional carbon cycle due to ongoing climate change.

  8. Hydromechanical Simulations of Surface Uplift due to CO2 Injection at In Salah (Invited)

    Science.gov (United States)

    Morris, J. P.; Hao, Y.; Foxall, W.; McNab, W. W.

    2009-12-01

    We present recent simulations of the hydromechanical response of the reservoir and overburden associated with CO2 injection at In Salah. Using the best available field data for the reservoir and fault network properties, we are able to demonstrate excellent agreement between simulation and observation. These results are providing new insight into the fate of the CO2 about one of the injectors where intriguing morphology was observed in surface uplift. Additionally, this work is helping to better establish the advantages and limitations of interpreting surface displacements to guide our understanding of fluid fate. The In Salah Project (a joint venture of BP, StatoilHydro and Sonatrach) includes a CO2 sequestration effort that has successfully injected millions of tons of CO2 into a deep saline formation close to a producing gas field in Algeria. We have been funded by the Joint Industry Project (A consortium consisting of BP, StatoilHydro and Sonatrach, hereafter the JIP) and the U.S. Department of Energy to investigate the role of injection induced mechanical deformation and geochemical alteration at the In Salah CO2 storage project. Here we focus upon the hydromechanical portion of the study. We have performed detailed simulations of the hydromechanical response in the vicinity of the KB-502 CO2 injector specifically because the morphology of the observed surface deformation differed from that above the other injectors at the field. First we performed a geomechanical analysis to predict which faults are flow conduits and which are flow barriers. NUFT simulations were performed based upon this information using permeability fields for the reservoir provided by the JIP. These results indicate that the presence of faults in the vicinity of the KB-502 injector may be responsible for the early breakthrough of CO2 observed at a nearby well, KB-5. We have simulated the mm-scale uplift of the overburden and compared the results with observed deformation using InSAR data

  9. Influence of secondary treatment with CO2 laser irradiation for mitigation site on fused silica surface

    Science.gov (United States)

    Jiang, Yong; Zhou, Qiang; Qiu, Rong; Gao, Xiang; Wang, Hui-Li; Yao, Cai-Zhen; Wang, Jun-Bo; Zhao, Xin; Liu, Chun-Ming; Xiang, Xia; Zu, Xiao-Tao; Yuan, Xiao-Dong; Miao, Xin-Xiang

    2016-10-01

    The ablation debris and raised rim, as well as residual stress and deep crater will be formed during the mitigation of damage site with a CO2 laser irradiation on fused silica surface, which greatly affects the laser damage resistance of optics. In this study, the experimental study combined with numerical simulation is utilized to investigate the effect of the secondary treatment on a mitigated site by CO2 laser irradiation. The results indicate that the ablation debris and the raised rim can be completely eliminated and the depth of crater can be reduced. Notable results show that the residual stress of the mitigation site after treatment will reduce two-thirds of the original stress. Finally, the elimination and the controlling mechanism of secondary treatment on the debris and raised rim, as well as the reasons for changing the profile and stress are analyzed. The results can provide a reference for the optimization treatment of mitigation sites by CO2 laser secondary treatment. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505170, 61505171, and 51535003), the Joint Fund of the National Natural Science Foundation of China, the Chinese Academy of Engineering Physics (Grant No. U1530109), and the China Postdoctoral Science Foundation (Grant No. 2016M592709).

  10. An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

    Directory of Open Access Journals (Sweden)

    MILAN S. TRTICA

    2000-06-01

    Full Text Available There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (b-, t1/2 = 30.17 y. Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.

  11. Probing Water and CO2 Interactions at the Surface of Collapsed Titania Nanotubes Using IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Kaustava Bhattacharyya

    2015-08-01

    Full Text Available Collapsed titania nanotubes (cTiNT were synthesized by the calcination of titania nanotubes (TiNT at 650 °C, which leads to a collapse of their tubular morphology, a substantial reduction in surface area, and a partial transformation of anatase to the rutile phase. There are no significant changes in the position of the XPS responses for Ti and O on oxidation or reduction of the cTiNTs, but the responses are more symmetric than those observed for TiNTs, indicating fewer surface defects and no change in the oxidation state of titanium on oxidative and/or reductive pretreatment. The interaction of H2O and CO2 with the cTiNT surface was studied. The region corresponding to OH stretching absorptions extends below 3000 cm−1, and thus is broader than is typically observed for absorptions of the OH stretches of water. The exchange of protons for deuterons on exposure to D2O leads to a depletion of this extended absorption and the appearance of new absorptions, which are compatible with deuterium exchange. We discuss the source of this extended low frequency OH stretching region and conclude that it is likely due to the hydrogen-bonded OH stretches. Interaction of the reduced cTiNTs with CO2 leads to a similar but smaller set of adsorbed carbonates and bicarbonates as reported for reduced TiNTs before collapse. Implications of these observations and the presence of proton sources leading to hydrogen bonding are discussed relative to potential chemical and photochemical activity of the TiNTs. These results point to the critical influence of defect structure on CO2 photoconversion.

  12. Direct CO(2) laser-based generation of holographic structures on the surface of glass.

    Science.gov (United States)

    Wlodarczyk, Krystian L; Weston, Nicholas J; Ardron, Marcus; Hand, Duncan P

    2016-01-25

    A customized CO(2) laser micromachining system was used for the generation of phase holographic structures directly on the surface of fused silica (HPFS(®)7980 Corning) and Borofloat(®)33 (Schott AG) glass. This process used pulses of duration 10µs and nominal wavelength 10.59µm. The pulse energy delivered to the glass workpiece was controlled by an acousto-optic modulator. The laser-generated structures were optically smooth and crack free. We demonstrated their use as diffractive optical elements (DOEs), which could be exploited as anti-counterfeiting markings embedded into valuable glass-made components and products.

  13. CO2 laser conditioning of porcelain surfaces for bonding metal orthodontic brackets.

    Science.gov (United States)

    Ahrari, Farzaneh; Heravi, Farzin; Hosseini, Mohsen

    2013-07-01

    Bonding to porcelain remains to be a challenge in orthodontic treatments. The objective of this study was to evaluate the effect of CO2 laser conditioning of porcelain surfaces on shear bond strength (SBS) of orthodontic brackets. Eighty feldspathic porcelain specimens were divided into four groups of 20. In each group, half of the porcelain surfaces were deglazed, while the others remained glazed. The specimens in groups 1 to 3 were treated with a fractional CO2 laser for 10 s using 10 mJ of energy, frequency of 200 Hz and powers of 10 W (group 1), 15 W (group 2) and 20 W (group 3). In group 4, a 9.6 % hydrofluoric (HF) acid gel was used for 2 min. A silane coupling agent was applied before bracket bonding, and the SBS was measured with a universal testing machine after 24 h. Deglazing caused significant increase in SBS of laser treated porcelain surfaces (p porcelain.

  14. Selectivity and Self Diffusion of CO2 and h2 in a Mixture on a Graphite Surface

    Science.gov (United States)

    Trinh, Thuat; Kjelstrup, Signe; Vlugt, Thijs; Bedeaux, Dick; Hägg, May-Britt

    2013-12-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250 ̶ 550K). The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields and with Density Functional Theory (DFT). The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  15. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface.

    Science.gov (United States)

    Trinh, Thuat T; Vlugt, Thijs J H; Hägg, May-Britt; Bedeaux, Dick; Kjelstrup, Signe

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250-550 K). The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields (FFs) and with Density Functional Theory (DFT). The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self-diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  16. SELECTIVITY AND SELF DIFFUSION OF CO2 AND H2 IN A MIXTURE ON A GRAPHITE SURFACE

    Directory of Open Access Journals (Sweden)

    Thuat Thanh Trinh

    2013-12-01

    Full Text Available We performed classical molecular dynamics (MD simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30 and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250 ̶ 550K. The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields and with Density Functional Theory (DFT. The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  17. Clumped isotopes in near-surface atmospheric CO2 over land, coast and ocean in Taiwan and its vicinity

    Science.gov (United States)

    Hussain Laskar, Amzad; Liang, Mao-Chang

    2016-09-01

    Molecules containing two rare isotopes (e.g., 13C18O16O in CO2), called clumped isotopes, in atmospheric CO2 are powerful tools to provide an alternative way to independently constrain the sources of CO2 in the atmosphere because of their unique physical and chemical properties. We presented clumped isotope data (Δ47) in near-surface atmospheric CO2 from urban, suburban, ocean, coast, high mountain ( ˜ 3.2 km a.s.l.) and forest in Taiwan and its vicinity. The primary goal of the study was to use the unique Δ47 signature in atmospheric CO2 to show the extents of its deviations from thermodynamic equilibrium due to different processes such as photosynthesis, respiration and local anthropogenic emissions, which the commonly used tracers such as δ13C and δ18O cannot provide. We also explored the potential of Δ47 to identify/quantify the contribution of CO2 from various sources. Atmospheric CO2 over ocean was found to be in thermodynamic equilibrium with the surrounding surface sea water. Respired CO2 was also in close thermodynamic equilibrium at ambient air temperature. In contrast, photosynthetic activity result in significant deviation in Δ47 values from that expected thermodynamically. The disequilibrium could be a consequence of kinetic effects associated with the diffusion of CO2 in and out of the leaf stomata. We observed that δ18O and Δ47 do not vary similarly when photosynthesis was involved unlike simple water-CO2 exchange. Additionally we obtained Δ47 values of car exhaust CO2 that were significantly lower than the atmospheric CO2 but higher than that expected at the combustion temperature. In urban and suburban regions, the Δ47 values were found to be lower than the thermodynamic equilibrium values at the ambient temperature, suggesting contributions from local combustion emission.

  18. Surface treatment of dental porcelain: CO2 laser as an alternative to oven glaze.

    Science.gov (United States)

    Sgura, Ricardo; Reis, Mariana Cavalcante; Hernandes, Antonio Carlos; de Abreu Fantini, Márcia Carvalho; Andreeta, Marcello Rubens Barsi; Medeiros, Igor Studart

    2015-02-01

    This work tested continuous CO2 laser as a surface treatment to dental porcelain and compared it to oven glaze (auto-glaze) by means of roughness and color parameters. Three commercial veneering porcelains with different crystalline content were tested: VM7, VM9, and VM13. Porcelain discs (3.5 × 2.0 mm, diameter × height) were sintered and had one side ground by a diamond bur (45 μm) simulating a chairside adjustment in a clinical office. Specimens (n = 7) were divided into the following groups: C--control (no treatment), G--auto-glaze (oven), and L--surface continuous irradiation with CO2 laser (Gem Laser, Coherent; λ = 10.6 μm). Laser was tested in three exposure times (3, 4, or 5 min) and two irradiances (45 and 50 W/cm(2)). Roughness parameters (Ra, Rz, and Rpm/Rz) were measured using a rugosimeter (Surftest 301, Mitutoyo). Color differences (ΔE) between the G and L groups were calculated (VITA Easyshade); ΔE values up to 3.3 were considered as not perceivable. A surface analysis was conducted by stereomicroscopy (Olympus SZ61) and SEM (Stereoscan 440, LEO). Crystalline content of specimens from groups C and L (50 W/cm(2), 5 min) was assessed by X-ray diffraction and then compared. Surface roughness (Ra and Rz) observed for laser-irradiated groups was similar to G for all studied porcelains. Rpm/Rz ratios were near 1.0 for all groups that indicated a sharp ridge profile for all specimens. Only one laser condition studied (50 W/cm(2), 3 min) from VM7 porcelain resulted in color difference (ΔE = 3.5) to G. Specimens irradiated with 50 W/cm(2) for 5 min presented the smoother surface observed by SEM, comparable to G. X-ray diffraction data revealed an increase in leucite crystallite size for VM9 and VM13 porcelains after laser treatment. Regarding roughness, continuous CO2 laser applied on porcelain surface was as effective as conventional oven auto-glaze.

  19. The doubled CO2 climate - Impact of the sea surface temperature gradient

    Science.gov (United States)

    Rind, David

    1987-01-01

    The Goddard Institute for Space Studies (GISS) GCM of Hansen et al. (1983) was run, with 4 deg x 5 deg resolution, with doubled CO2 and two sets of sea surface temperature gradient distributions. One set was derived from the equilibrium doubled CO2 run of the 8 deg x 10 deg GISS GCM, with minimal high latitude amplification. The other set resembled closely the GFDL model results, with greater amplification. Both experiments had the same global mean surface air temperature change. The two experiments were often found to produce substantially different climate characteristics. With reduced high latitude amplification (set one), and thus, more equatorial warming, there was a greater increase in specific humidity and the greenhouse capacity of the atmosphere, resulting in a warmer atmosphere in general. Features such as the low-latitude precipitation, Hadley cell intensity, jet stream magnitude, and atmospheric energy transports all increased in comparison with the control run. In contrast, these features all decreased in the experiment with greater high latitude amplification (set two).

  20. Angiosperms evolved a higher mesophyll surface area per volume to maximize exchange surface under a low CO2 world

    Science.gov (United States)

    Théroux-Rancourt, Guillaume; Mason Earles, J.; Gilbert, Matthew E.; Zwieniecki, Maciej A.; Boyce, C. Kevin; McElrone, Andrew; Brodersen, Craig

    2017-04-01

    Variation in leaf mesophyll structure strongly affects CO2 diffusion and photosynthetic rates. One key trait is the surface of mesophyll cells exposed to intercellular airspace (Sm) which increases mesophyll conductance. Consequently, Sm is a key control of CO2 diffusion among species and genotypes. Using Sm values from the literature (> 200 species with 500 data points) and from our high-resolution X-ray computed tomography (μCT) dataset (currently 117 species), Sm shows little variation from pteridophytes to early angiosperms, while eudicots show the greatest structural diversity. However, Sm increases with total thickness of the mesophyll. By considering the exposed surface of the mesophyll to the intercellular air space (IAS) on a leaf or mesophyll volume (Ames/V mes) rather than leaf area basis (Sm), we demonstrate that angiosperms, and most specifically commelinids and non-basal eudicots, have constructed leaves with more surface per volume, while gymnosperms keep a constant Ames/V mes ratio. Thus, this strong phylogenetic signal suggests that angiosperms have developed IAS properties favoring leaves with higher surface to volume ratio, trait that allowed for the potential of high productivity even as atmospheric CO2 declined over the Cenozoic.

  1. Spatial variations in daily average CO2 concentrations above wetland surface of Xianghai National Nature Reserve, China

    Institute of Scientific and Technical Information of China (English)

    BAI Jun-hong; OUYANG Hua; WANG Qing-gai; ZHOU Cai-ping; XU Xiao-feng

    2005-01-01

    Horizontal and vertical variations of daily average CO2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000. The primary purpose was to study spatial distribution characteristics of CO2 concentration on the four levels of height(0. 1 m, 0.6 m, 1.2 m and 2 m) and compare the differences of CO2 concentration under different land covers. Results showed that daily average CO2 concentration above wetland surface in Xianghai National Natural Reserve was lower than that above other wetlands in northeast China as well as the worldwide average, suggesting that Xianghai wetland absorbed CO2 in August and acted as"sink" of CO2. The horizontal variations on the four levels of height along the latitude were distinct, and had the changing tendency of"decreasing after increasing" with the increase of height. The areas with obvious variations were consistent on different levels of height,and those with the highest variations appeared above surface of shore, sloping field, Typha wetland and Phragmites wetland; the vertical variations were greatly different, with the higher variations in Phragmites wetland and Typha wetland, and the lands near the shore and the sloping field with the lower variations. Spatial variations of daily average CO2 concentrations above wetland surface were affected by surface qualities and land covers.

  2. Interfacial Interactions and Wettability Evaluation of Rock Surfaces for CO2 Storage

    NARCIS (Netherlands)

    Shojai Kaveh, N.

    2014-01-01

    To reduce CO2 emissions into the atmosphere, different scenarios are proposed to capture and store carbon dioxide (CO2) in geological formations (CCS). Storage strategies include CO2 injection into deep saline aquifers, depleted gas and oil reservoirs, and unmineable coal seams. To identify a secure

  3. Colour and chemical changes of the lime wood surface due to CO2 laser thermal modification

    Science.gov (United States)

    Kubovský, Ivan; Kačík, František

    2014-12-01

    We studied colour and main wood components changes of lime wood caused by CO2 laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO2 laser beam (wavelength of 10.6 μm) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm-2) lightness (ΔL*) decrease and increase of the total colour difference (ΔE*) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

  4. The effects of elevated CO2 and eutrophication on surface elevation gain in a European salt marsh.

    Science.gov (United States)

    Reef, Ruth; Spencer, Tom; Mӧller, Iris; Lovelock, Catherine E; Christie, Elizabeth K; McIvor, Anna L; Evans, Ben R; Tempest, James A

    2017-02-01

    Salt marshes can play a vital role in mitigating the effects of global environmental change by dissipating incident storm wave energy and, through accretion, tracking increasing water depths consequent upon sea level rise. Atmospheric CO2 concentrations and nutrient availability are two key variables that can affect the biological processes that contribute to marsh surface elevation gain. We measured the effects of CO2 concentrations and nutrient availability on surface elevation change in intact mixed-species blocks of UK salt marsh using six open-top chambers receiving CO2 -enriched (800 ppm) or ambient (400 ppm) air. We found more rapid surface elevation gain in elevated CO2 conditions: an average increase of 3.4 mm over the growing season relative to ambient CO2 . Boosted regression analysis to determine the relative influence of different parameters on elevation change identified that a 10% reduction in microbial activity in elevated CO2 -grown blocks had a positive influence on elevation. The biomass of Puccinellia maritima also had a positive influence on elevation, while other salt marsh species (e.g. Suaeda maritima) had no influence or a negative impact on elevation. Reduced rates of water use by the vegetation in the high CO2 treatment could be contributing to elevation gain, either directly through reduced soil shrinkage or indirectly by decreasing microbial respiration rates due to lower redox levels in the soil. Eutrophication did not influence elevation change in either CO2 treatment despite doubling aboveground biomass. The role of belowground processes (transpiration, root growth and decomposition) in the vertical adjustment of European salt marshes, which are primarily minerogenic in composition, could increase as atmospheric CO2 concentrations rise and should be considered in future wetland models for the region. Elevated CO2 conditions could enhance resilience in vulnerable systems such as those with low mineral sediment supply or where

  5. Implications of a Changing Arctic on Summertime Surface Seawater pCO2 Variations in the Eastern Canadian Arctic

    Science.gov (United States)

    Burgers, T.; Miller, L. A.; Thomas, H.; Else, B. G. T.; Gosselin, M.; Papakyriakou, T. N.

    2015-12-01

    Arctic marine carbonate chemistry and rates of air-sea CO2 exchange are anticipated to be affected by current changes in sea-ice structure and extent, freshwater inputs, ocean circulation patterns, and the seasonality of phytoplankton blooms. This study examines how such changes will impact rates of air-sea CO2 exchange in northern Baffin Bay, Nares Strait, and the eastern Canadian Arctic Archipelago. This complex oceanographic region includes the North Water polynya; one of the most biologically productive areas in the Arctic Ocean, and the convergence site of the warm West Greenland Current with cold exported Arctic waters. Continuous measurements of atmospheric and surface seawater CO2 (pCO2) were collected onboard the Canadian Coast Guard Ship Amundsen during its 2013 and 2014 summer cruises. Surface seawater pCO2 displayed considerable variability (145 - 389 ppm), but never exceeded atmospheric concentrations. Calculated CO2 fluxes ranged from 0 to -45 mmol m-2 day-1 (oceanic uptake), and were estimated using the Sweeney et al. (2007) parameterization with in-situ wind speed measurements. Ancillary measurements of chlorophyll a reveal low productivity in surface waters during mid-summer with isolated sub-surface blooms. This is likely the result of nutrient limitation within the highly stratified polar mixed layer (PML). Measurements of stable oxygen isotope ratios (δ18O) and total alkalinity were used to estimate freshwater inputs (sea-ice melt vs. meteoric water) to the PML. These and in-situ observations of sea ice cover were used to interpret seawater pCO2 variations. Surface waters influenced by sea-ice melt exhibit lower pCO2 than those influenced by meteoric water. The results of this investigation shed light on the future role of this region as a summertime sink of atmospheric CO2.

  6. Surface Roughness Study on Microchannels of CO2 Laser Fabricating Pmma-Based Microfluidic Chip

    Science.gov (United States)

    Chen, Xueye; Li, Tiechuan; Fu, Baoding

    A novel method named soak sacrificial layer ultrasonic method (SSLUM) has been presented for optimizing the surface roughness of the microchannels of polymethyl methacrylate (PMMA)-based microfluidic chips. CO2 laser was used for ablative microchannels on the PMMA sheet, and the effects of key parameters including laser power, laser ablation speed and solution concentration on the surface roughness of microchannels were estimated and optimized by SSLUM. The experimental observation demonstrates that the surface roughness results mainly from the residues on the channel wall, which are produced by the bubbles movement and bursting. The research results show that the surface roughness can be improved effectively by using SSLUM. In our experiment, the best value was Ra = 110nm with laser power 12W, laser ablation speed 10mm/s, the solution concentration 75%, and the time of ultrasonic vibration 25min. SSLUM is proven to be an effective, simple and rapid method for optimizing the surface roughness of microchannels of microfluidic chips.

  7. Spatial and temporal distribution characteristics of near-surface CO2 concentration over China based on GOSAT data

    Science.gov (United States)

    Zhao, Jing; Cui, Weihong; Sun, Yunhua

    2014-11-01

    To study the spatial and temporal distribution characteristics of near-surface CO2 concentration over China, the data of GOSAT L4B and auxiliary data of Mt Waliguan background observations, population density, total energy consumption (coal) and GDP in 2009 were applied to this study. The ArcGIS Geostatistical Analytical Method was used. The ground-based validation was processed by comparing GOSAT data with Mt Waliguan background observations. The variation characteristics of the near-surface CO2 concentration over China was analysed spatially and temporally. The results show that: GOSAT retrieved near-surface products are consistent with Mt Waliguan ground-based measurement; Near-surface CO2 concentration over China is relatively concentrated, and has significant differences between the East and the West, with a overall characteristic that CO2 concentration in the east of China is high and in the west is low; Near-surface CO2 concentration over China has a significant seasonal variation characteristic, and the monthly average concentration rise to the highest value of 396.512 ppmv in April (spring), which is significantly higher than other seasons, decline to the lowest value of 382.781 ppmv in July (summer); All relationships illustrate a big uncertainty, resulting a conclusion that the reasons causing the spatial distribution of near-surface CO2 concentration may be varied, could not be easily determined as anthropogenic or natural ressons, which need further study.

  8. Adaptation response surfaces for managing wheat under perturbed climate and CO2 in a Mediterranean environment

    DEFF Research Database (Denmark)

    Ruiz-Ramos, M.; Ferrise, Roberto; Rodríguez, A

    2017-01-01

    Adaptation of crops to climate change has to be addressed locally due to the variability of soil, climate and the specific socio-economic settings influencing farm management decisions. Adaptation of rainfed cropping systems in the Mediterranean is especially challenging due to the projected...... decline in precipitation in the coming decades, which will increase the risk of droughts. Methods that can help explore uncertainties in climate projections and crop modelling, such as impact response surfaces (IRSs) and ensemble modelling, can then be valuable for identifying effective adaptations. Here...... on the "According to Our Current Knowledge" (AOCK) concept, which has been formalized here. Adaptations were based on changes in cultivars and management regarding phenology, vernalization, sowing date and irrigation. The effects of adaptation options under changed precipitation (P), temperature (T), [CO2] and soil...

  9. Modeling ground surface uplift during CO2 sequestration: the case of In Salah, Algeria.

    Science.gov (United States)

    Rinaldi, Antonio Pio; Rutqvist, Jonny; Finsterle, Stefan; Liu, Hui-Hai

    2016-04-01

    Observable ground deformation, common in storage projects, carries useful information on processes occurring at the injection depth. The Krechba gas field at In Salah (Algeria) is one of the best known sites for studying ground surface deformation during geological storage. Being the first industrial-scale on-shore CO2 demonstration project, the site is well known for satellite-based ground-deformation monitoring data of remarkable quality. In this work, we carry out coupled fluid flow and geomechanical simulations to understand the uplift at three different CO2 injection wells (KB-501, KB-502, KB-503). Previous numerical studies focused on the KB-502 injection well, where a double-lobe uplift pattern has been observed in the ground-deformation data. The observed uplift patterns at KB-501 and KB-503 are different, but also indicate the influence of deep fracture zone mechanical responses. The current study improves the previous modeling approach by introducing an injection reservoir and a fracture zone, both responding to a Mohr-Coulomb failure criterion. In addition, we model a stress-dependent permeability and bulk modulus, according to a dual continuum model. Mechanical and hydraulic properties were determined through inverse modeling by matching the simulated spatial and temporal evolution of uplift to the corresponding InSAR observations as well as by matching simulated and measured pressures. The numerical simulations are in excellent agreement with observed spatial and temporal variation of ground surface uplift, as well as with measured pressures. The estimated values for the parameterized mechanical and hydraulic properties are in good agreement with previous numerical results, although with uncertainty.

  10. [Research on the spectral feature and identification of the surface vegetation stressed by stored CO2 underground leakage].

    Science.gov (United States)

    Chen, Yun-Hao; Jiang, Jin-Bao; Steven, Michael D; Gong, A-Du; Li, Yi-Fan

    2012-07-01

    With the global climate warming, reducing greenhouse gas emissions becomes a focused problem for the world. The carbon capture and storage (CCS) techniques could mitigate CO2 into atmosphere, but there is a risk in case that the CO2 leaks from underground. The objective of this paper is to study the chlorophyll contents (SPAD value), relative water contents (RWC) and leaf spectra changing features of beetroot under CO2 leakage stress through field experiment. The result shows that the chlorophyll contents and RWC of beetroot under CO2 leakage stress become lower than the control beetroot', and the leaf reflectance increases in the 550 nm region and decreases in the 680nm region. A new vegetation index (R550/R680) was designed for identifying beetroot under CO2 leakage stress, and the result indicates that the vegetation index R550/R680 could identify the beetroots after CO2 leakage for 7 days. The index has strong sensitivity, stability and identification for monitoring the beetroots under CO2 stress. The result of this paper has very important meaning and application values for selecting spots of CCS project, monitoring and evaluating land-surface ecology under CO2 stress and monitoring the leakage spots by using remote sensing.

  11. CO2 dissociation activated through electron attachment on reduced rutile TiO2(110)-1x1 surface

    CERN Document Server

    Tan, Shijing; Zhao, Jin; Wang, Zhuo; Ma, Chuanxu; Zhao, Aidi; Wang, Bing; Luo, Yi; Yang, Jinlong; Hou, Jianguo

    2011-01-01

    Converting CO$_2$ to useful compounds through the solar photocatalytic reduction has been one of the most promising strategies for artificial carbon recycling. The highly relevant photocatalytic substrate for CO$_2$ conversion has been the popular TiO$_2$ surfaces. However, the lack of accurate fundamental parameters that determine the CO$_2$ reduction on TiO$_2$ has limited our ability to control these complicated photocatalysis processes. We have systematically studied the reduction of CO2 at specific sites of the rutile TiO$_2$(110)-1x1 surface using scanning tunneling microscopy at 80 K. The dissociation of CO2 molecules is found to be activated by one electron attachment process and its energy threshold, corresponding to the CO$_2^{\\dot-}$/CO$_2$ redox potential, is unambiguously determined to be 2.3 eV higher than the onset of the TiO$_2$ conduction band. The dissociation rate as a function of electron injection energy is also provided. Such information can be used as practical guidelines for the design...

  12. Response of sea surface fugacity of CO2 to the SAM shift south of Tasmania: Regional differences

    Science.gov (United States)

    Xue, Liang; Gao, Libao; Cai, Wei-Jun; Yu, Weidong; Wei, Meng

    2015-05-01

    Using observational data collected south of Tasmania during 14 austral summer cruises during 1993-2011, we examined the response of sea surface fugacity of carbon dioxide (fCO2) to the Southern Annular Mode (SAM) shift, which occurred around 2000. In the southern part of the Southern Ocean (SO) or the Polar Zone (PZ) and the Polar Frontal Zone (PFZ), fCO2 increased faster at the sea surface than in the atmosphere before the SAM shift, but not after the shift. In the northern part of the SO or the Subantarctic Zone (SAZ), however, surface fCO2 increased faster than atmospheric fCO2 both before and after the shift. The SAM shift had an important influence on the surface fCO2 trend in the PZ and PFZ but not in the SAZ, which we attribute to differences in regional oceanographic processes (upwelling versus nonupwelling). The SAM shift may have reversed the negative trend of SO CO2 uptake.

  13. A comparison of tool-repair methods using CO 2 laser surfacing and arc surfacing

    Science.gov (United States)

    Grum, J.; Slabe, J. M.

    2003-03-01

    The life of loaded machine elements and the vital parts of tools can be successfully extended by systematic maintenance and the timely repair of damaged surfaces. It has been proved that with the regular maintenance of tool parts the cost of the tool in the price of a finished product can be considerably reduced. It is a very economical practise to manufacture certain parts from low-cost, tough structural steel on which a layer of wear-resistant alloy has been surfaced. In such a case the volume fraction of the surfaced layer is usually much lower than 10% of the total volume of the tool or the machine element. In this paper, we report some of our latest results involving comparative studies of repair surfacing on maraging steel and the cladding of common structural steel with a Ni-Co-Mo alloy similar to the maraging steel using a laser process and submerged-arc surfacing. The results are based on micro-structural and micro-chemical analyses of the surfaced layer and are supported by analyses of the micro-hardness and the residual stresses, carried out on suitably adapted flat specimens.

  14. Surface ocean pH response to variations in pCO 2 through two full glacial cycles

    Science.gov (United States)

    Hönisch, Bärbel; Hemming, N. Gary

    2005-07-01

    Knowledge of past atmospheric pCO 2 is important for evaluating the role of greenhouse gases in climate forcing. Ice core records show the tight correlation between climate change and pCO 2, but records are limited to the past ˜900 kyr. We present surface ocean pH and PCO 2 data, reconstructed from boron isotopes in planktonic foraminifera over two full glacial cycles (0-140 and 300-420 kyr). The data co-vary strongly with the Vostok pCO 2-record and demonstrate that the coupling between surface ocean chemistry and the atmosphere is recorded in marine archives, allowing for quantitative estimation of atmospheric pCO 2 beyond the reach of ice cores.

  15. Surface heat flow and CO2 emissions within the Ohaaki hydrothermal field, Taupo Volcanic Zone, New Zealand

    Science.gov (United States)

    Rissmann, C.; Christenson, B.; Werner, C.; Leybourne, M.; Cole, J.; Gravley, D.

    2012-01-01

    Carbon dioxide emissions and heat flow have been determined from the Ohaaki hydrothermal field, Taupo Volcanic Zone (TVZ), New Zealand following 20a of production (116MW e). Soil CO2 degassing was quantified with 2663 CO2 flux measurements using the accumulation chamber method, and 2563 soil temperatures were measured and converted to equivalent heat flow (Wm -2) using published soil temperature heat flow functions. Both CO2 flux and heat flow were analysed statistically and then modelled using 500 sequential Gaussian simulations. Forty subsoil CO 2 gas samples were also analysed for stable C isotopes. Following 20a of production, current CO2 emissions equated to 111??6.7T/d. Observed heat flow was 70??6.4MW, compared with a pre-production value of 122MW. This 52MW reduction in surface heat flow is due to production-induced drying up of all alkali-Cl outflows (61.5MW) and steam-heated pools (8.6MW) within the Ohaaki West thermal area (OHW). The drying up of all alkali-Cl outflows at Ohaaki means that the soil zone is now the major natural pathway of heat release from the high-temperature reservoir. On the other hand, a net gain in thermal ground heat flow of 18MW (from 25MW to 43.3??5MW) at OHW is associated with permeability increases resulting from surface unit fracturing by production-induced ground subsidence. The Ohaaki East (OHE) thermal area showed no change in distribution of shallow and deep soil temperature contours despite 20a of production, with an observed heat flow of 26.7??3MW and a CO 2 emission rate of 39??3T/d. The negligible change in the thermal status of the OHE thermal area is attributed to the low permeability of the reservoir beneath this area, which has limited production (mass extraction) and sheltered the area from the pressure decline within the main reservoir. Chemistry suggests that although alkali-Cl outflows once contributed significantly to the natural surface heat flow (~50%) they contributed little (99% of the original CO 2

  16. CO2 leakage from carbon dioxide capture and storage (CCS) systems affects organic matter cycling in surface marine sediments.

    Science.gov (United States)

    Rastelli, Eugenio; Corinaldesi, Cinzia; Dell'Anno, Antonio; Amaro, Teresa; Greco, Silvestro; Lo Martire, Marco; Carugati, Laura; Queirós, Ana M; Widdicombe, Stephen; Danovaro, Roberto

    2016-12-01

    Carbon dioxide capture and storage (CCS), involving the injection of CO2 into the sub-seabed, is being promoted worldwide as a feasible option for reducing the anthropogenic CO2 emissions into the atmosphere. However, the effects on the marine ecosystems of potential CO2 leakages originating from these storage sites have only recently received scientific attention, and little information is available on the possible impacts of the resulting CO2-enriched seawater plumes on the surrounding benthic ecosystem. In the present study, we conducted a 20-weeks mesocosm experiment exposing coastal sediments to CO2-enriched seawater (at 5000 or 20,000 ppm), to test the effects on the microbial enzymatic activities responsible for the decomposition and turnover of the sedimentary organic matter in surface sediments down to 15 cm depth. Our results indicate that the exposure to high-CO2 concentrations reduced significantly the enzymatic activities in the top 5 cm of sediments, but had no effects on subsurface sediment horizons (from 5 to 15 cm depth). In the surface sediments, both 5000 and 20,000 ppm CO2 treatments determined a progressive decrease over time in the protein degradation (up to 80%). Conversely, the degradation rates of carbohydrates and organic phosphorous remained unaltered in the first 2 weeks, but decreased significantly (up to 50%) in the longer term when exposed at 20,000 ppm of CO2. Such effects were associated with a significant change in the composition of the biopolymeric carbon (due to the accumulation of proteins over time in sediments exposed to high-pCO2 treatments), and a significant decrease (∼20-50% at 5000 and 20,000 ppm respectively) in nitrogen regeneration. We conclude that in areas immediately surrounding an active and long-lasting leak of CO2 from CCS reservoirs, organic matter cycling would be significantly impacted in the surface sediment layers. The evidence of negligible impacts on the deeper sediments should be considered with

  17. Surface and Subsurface Geochemical Monitoring of an EOR-CO2 Field: Buracica, Brazil Monitoring géochimique en surface et sub-surface d’un gisement en production par récupération assistée et injection de CO2 : le champ de Buracica, Brésil

    Directory of Open Access Journals (Sweden)

    Magnier C.

    2012-04-01

    éservoir à la surface est détaillée. Les campagnes de prélèvement se sont déroulées sur trois périodes en deux ans, permettant de mesurer la variabilité des teneurs en CO2 dans les sols et dans les réservoirs pétroliers. La distribution du CO2 en surface varie de 0,8 à 14 % et peut être contrôlée en partie par les propriétés des sols et la topographie. Les résultats isotopiques du δ13CCO2 varient entre –15 et –23 ‰ et suggèrent que le flux de CO2 soit principalement biogénique. Le gaz injecté, puis produit à Buracica, est hétérogène en composition de par la récupération tertiaire du gisement induisant une infiltration de CO2 à des niveaux variables et les variations de perméabilité au sein même du réservoir. Les résultats montrent qu’il est, dans ce cas, difficile de tracer le CO2 du réservoir à la surface en fonction des valeurs isotopiques δ13CCO2. Notre approche démontre le fort potentiel des gaz rares pour discriminer des mélanges, même à des teneurs faibles de CO2 (~1 %. Les résultats illustrent le potentiel de ces nouvelles techniques de monitoring géochimiques pour suivre le CO2 dans les projets de séquestration combinant les signatures du carbone stable avec celles des gaz rares.

  18. Studies of surface processes of electrocatalytic reduction of CO2 on Pt(210), Pt(310) and Pt(510)

    Institute of Scientific and Technical Information of China (English)

    FAN; ChunJie; FAN; YouJun; ZHEN; ChunHua; ZHENG; QingWei; SUN; ShiGang

    2007-01-01

    Surface processes of CO2 reduction on Pt(210), Pt(310), and Pt(510) electrodes were studied by cyclic voltammetry. Different surface structures of these platinum single crystal electrodes were obtained by various treatment conditions. The experimental results illustrated that the electrocatalytic activity of Pt single crystal electrodes towards CO2 reduction is decreased in an order of Pt(210)>Pt(310)>Pt(510), i.e., with the decrease of (110) step density on well-defined surfaces. When the surfaces were reconstructed due to oxygen adsorption, the catalytic activity of all the three electrodes has been enhanced to a certain extent. Although the activity order remains unchanged, the electrocatalytic activity has been enhanced more significantly as the density of (110) step sites is more intensive on the Pt single crystal surface. It has revealed that the more open the surface structure is, the more active the Pt single crystal electrode will be, and the easier for the electrode to be transformed into a surface structure that exhibits higher activity under external inductions. However, the relatively ordered surfaces of Pt single crystal electrode are comparatively stable under the same external inductions. The present study has gained knowledge on the interaction between CO2 and Pt single crystal electrode surfaces at a microscopic level, and thrown new insight into understanding the surface processes of electrocatalytic reduction of CO2.

  19. Surface exposure to sunlight stimulates CO2 release from permafrost soil carbon in the Arctic.

    Science.gov (United States)

    Cory, Rose M; Crump, Byron C; Dobkowski, Jason A; Kling, George W

    2013-02-26

    Recent climate change has increased arctic soil temperatures and thawed large areas of permafrost, allowing for microbial respiration of previously frozen C. Furthermore, soil destabilization from melting ice has caused an increase in thermokarst failures that expose buried C and release dissolved organic C (DOC) to surface waters. Once exposed, the fate of this C is unknown but will depend on its reactivity to sunlight and microbial attack, and the light available at the surface. In this study we manipulated water released from areas of thermokarst activity to show that newly exposed DOC is >40% more susceptible to microbial conversion to CO(2) when exposed to UV light than when kept dark. When integrated over the water column of receiving rivers, this susceptibility translates to the light-stimulated bacterial activity being on average from 11% to 40% of the total areal activity in turbid versus DOC-colored rivers, respectively. The range of DOC lability to microbes seems to depend on prior light exposure, implying that sunlight may act as an amplification factor in the conversion of frozen C stores to C gases in the atmosphere.

  20. An Updated Estimation of Radiative Forcing due to CO2 and Its Effect on Global Surface Temperature Change

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; ZHANG Ruoyu; SHI Guangyu

    2013-01-01

    New estimations of radiative forcing due to CO2 were calculated using updated concentration data of CO2 and a high-resolution radiative transfer model.The stratospheric adjusted radiative forcing (ARF)due to CO2 from the year 1750 to the updated year of 2010 was found to have increased to 1.95 W m-2,which was 17% larger than that of the IPCC's 4th Assessment Report because of the rapid increase in CO2 concentrations since 2005.A new formula is proposed to accurately describe the relationship between the ARF of CO2 and its concentration.Furthermore,according to the relationship between the ARF and surface temperature change,possible changes in equilibrium surface temperature were estimated under the scenarios that the concentration of CO2 increases to 1.5,2,2.5,3,3.5 and 4 times that of the concentration in the year 2008.The result was values of +2.2℃,+3.8℃,+5.1℃,+6.2℃,+7.1℃ and +8.0℃ respectively,based on a middle-level climate sensitivity parameter of 0.8 K (W m-2)-1.Non-equilibrium surface temperature changes over the next 500 years were also calculated under two kinds of emission scenarios (pulsed and sustained emissions) as a comparison,according to the Absolute Global Temperature change Potential (AGTP) of CO2.Results showed that CO2 will likely continue to contribute to global warming if no emission controls are imposed,and the effect on the Earth-atmosphere system will be difficult to restore to its original level.

  1. Localized CO2 laser treatment and post-heating process to reduce the growth coefficient of fused silica surface damage

    Institute of Scientific and Technical Information of China (English)

    Shizhen Xu; Xiaotao Zu; Xiaodong Yuan

    2011-01-01

    The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth. Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates. However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample. The damage grows with crack propagation for residual stress after CO2 laser irradiation. Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.%@@ The lifetime of optical components in high-fluence ultraviolet (UV) laser applications is typically limited by laser-initiated damage and its subsequent growth.Using 10.6-μm CO2 laser pulses, we successfully mitigate 355-nm laser induced damage sites on fused silica surface with dimensions less than 200 μm.The damage threshold increases and the damage growth mitigates.However, the growth coefficients of new damage on the CO2 laser processed area are higher than those of the original sample.The damage grows with crack propagation for residual stress after CO2 laser irradiation.Furthermore, post-heating is beneficial to the release of residual stress and slows down the damage growth.

  2. Dissolution and Sorption Processes on the Surface of Calcite in the Presence of High Co2+ Concentration

    Directory of Open Access Journals (Sweden)

    Jorge González-López

    2017-02-01

    Full Text Available The interaction of the calcite surface with Co2+-rich aqueous solutions ([Co2+aq]initial = 1000 ppm, i.e., ca. 17 mM was investigated by means of macroscopic experiments and surface spectroscopic techniques. In the case of the macroscopic experiments, calcite powder and monocrystals were immersed into solutions for different time periods (from 1 min to one month. The Ca concentrations in the filtrates was measured by means of atomic absorption spectrometry (AAS while the interacted solids were studied using a combination of X-ray photoelectron spectroscopy (XPS and 12C-rutherford backscattering spectrometry (12C-RBS. The macroscopic data showed a characteristic surface dissolution process, in parallel to the surface sorption processes. Adsorption and co-precipitation were seen for almost the entire immersion period for both calcite powder and monocrystals. The surface study by XPS (analyzed at a depth of approximately 12 nm suggested that adsorption takes place in the first hour of the interaction, followed by incorporation of Co2+ into calcite surface layers, leading to the formation of a Co2+-bearing surface (coprecipitate, which occurs over a period of hours and days. The 12C-RBS measurements on calcite { 10 1 ¯ 4 } indicated that the thickness of this surface co-precipitate was 270 nm after one day and then stabilized at 320 nm after more than a week.

  3. Effect of Surface Treatment with Carbon Dioxide (CO2) Laser on Bond Strength between Cement Resin and Zirconia

    OpenAIRE

    Kasraei, Shahin; Atefat, Mohammad; Beheshti, Maryam; Safavi, Nassimeh; Mojtahedi, Maryam; Rezaei-Soufi, Loghman

    2014-01-01

    Introduction: Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques, laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of Carbon Dioxide (CO2) Laser treatment on shear bond strength (SBS) of resin cement to zirconia ceramic.

  4. Controlling mechanisms of surface partial pressure of CO2 in Jiaozhou Bay during summer and the influence of heavy rain

    Science.gov (United States)

    Li, Yunxiao; Yang, Xufeng; Han, Ping; Xue, Liang; Zhang, Longjun

    2017-09-01

    Due to the combined effects of natural processes and human activities, carbon source/sink processes and mechanisms in the coastal ocean are becoming more and more important in current ocean carbon cycle research. Based on differences in the ratio of total alkalinity (TA) to dissolved inorganic carbon (DIC) associated with terrestrial input, biological process (production and respiration), calcium carbonate (CaCO3) process (precipitation and dissolution) and CO2 evasion/invasion, we discuss the mechanisms controlling the surface partial pressure of CO2 (pCO2) in Jiaozhou Bay (JZB) during summer and the influence of heavy rain, via three cruises performed in mid-June, early July and late July of 2014. In mid-June and in early July, without heavy rain or obvious river input, sea surface pCO2 ranged from 521 to 1080 μatm and from 547 to 998 μatm, respectively. The direct input of DIC from sewage and the intense respiration produced large DIC additions and the highest pCO2 values in the northeast of the bay near the downtown of Qingdao. However, in the west of the bay, significant CaCO3 precipitation led to DIC removal but no obvious increase in pCO2, which was just close to that in the central area. Due to the shallow depth and longer water residence time in this region, this pattern may be related to the sustained release of CO2 into the atmosphere. In late July, heavy rain promoted river input in the western and eastern portions of JZB. Strong primary production led to a significant decrease in pCO2 in the western area, with the lowest pCO2 value of 252 μatm. However, in the northeastern area, the intense respiration remained, and the highest pCO2 value was 1149 μatm. The average air-sea CO2 flux in mid-June and early July was 20.23 mmol m- 2 d- 1 and 23.56 mmol m- 2 d- 1, respectively. In contrast, in late July, sources became sinks for atmospheric CO2 in the western and central areas of the bay, halving the average air-sea CO2 flux to a value of 10.58 mmol m- 2

  5. Analysis of CO2 convection mechanisms associated to surface heating, by combining remote sensing data and in situ measurements

    Science.gov (United States)

    Tello, Marivi; Curcoll, Roger; Font, Anna; Morgu, Josep Anton; Rod, Xavier

    Assessing the mechanisms involved in the variability of carbon fluxes is crucial for the under-standing of the changing earth dynamics. In that sense, the aim of this work is to analyze CO2 convection mechanisms at a regional scale in the boundary layer and the lower troposphere by means of cross correlation of land surface temperature data, radio-soundings, wind speeds and in situ measurements of CO2 atmospheric mixing ratios. Since data is easier to acquire, ground level horizontal CO2 fluxes have been widely studied. In the contrary, vertical ones are still subject to uncertainties, even if they are necessary to understand 3D CO2 variability in the atmosphere. In particular, this paper focuses on the relationship between surface heating, convection and CO2 concentrations at different heights and, more generally, on the energy transfer between the surface and the air. The monitored area corresponds to a region on the North Eastern Iberian Peninsula, mainly devoted to agricultural activities. Different types of land covers are observed. On the one hand, in situ data has been collected by several flights during 2007 along the parallel 42o N following the "Crown" aircraft sampling approach [1] that integrates CO2 data obtained through horizontal transects and vertical profiles. This particular configuration is especially well suited for the evaluation of both horizontal and vertical CO2 fluxes. On the other hand, the radiometric land surface temperatures are obtained from the MODIS instrument onboard the Terra and the Aqua satellites. Besides, a flight campaign with an airborne sensor along the same transect in the parallel 42o N has been proposed in the scope of the MIDAS-6 project recently submitted. This project plans to improve soil moisture and ocean salinity products of the SMOS sensor recently launched and to demonstrate its applications. This will allow the study of moisture patterns in the monitored area at two different scales: that of the data collected

  6. Variability of shelf sea pH and surface water CO2 in response to North Atlantic Oscillation forcing

    Science.gov (United States)

    Salt, L.; Thomas, H.; Prowe, A. E. F.; Borges, A. V.; de Baar, H. J. W.

    2012-04-01

    High biological activity causes a distinct seasonality of surface water pH in the North Sea, which has been identified as a strong sink for atmospheric CO2 via a particularly effective shelf pump. The intimate connection between the North Sea and the North Atlantic suggests that the variability of the CO2 system of the North Atlantic Ocean may in part be responsible for the observed, but hitherto poorly understood variability of pH and CO2 in the North Sea. Here we investigate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic hemisphere in governing this variability. Based on three extensive observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. We argue that under NAO+ conditions higher rates of inflow of water from the North Atlantic Ocean limits seasonal shoaling of the summer mixed layer in the northern North Sea, diminishing the biological potential to lower pCO2 and raise pH. In addition the faster circulation of the North Sea enhances the shelf pump efficiency. These clear patterns are obscured by changing properties of the North Sea waters, masking or enforcing these effects on various time scales. Such controls indicate that inter-annual trends in the North Sea CO2 system must be carefully examined with consideration to the North Atlantic Oscillation.

  7. Density functional study of adsorptions of CO2, NO2 and SO2 molecules on Zn(0002) surfaces

    Science.gov (United States)

    Nugraha; Saputro, A. G.; Agusta, M. K.; Yuliarto, B.; Dipojono, H. K.; Maezono, R.

    2016-08-01

    We report on a theoretical study of adsorptions of CO2, NO2 and SO2 molecules on ZnO(0002) surfaces using density functional theory-based (DFT-based) calculations. These adsorptions are done on perfect and defective ZnO(0002) surfaces. We find that all of these molecules are chemically adsorbed on the perfect ZnO(0002) surface. In the presence of Zn vacancy, we find that the surface is only active toward SO2 molecule. On the hydroxylated ZnO(0002) surfaces, CO2 and SO2 molecules can react with the preadsorbed OH molecule to form various adsorbates such as: carboxyl (COOH), bicarbonate (CO3H), sulfonyl hydroxide (SO3H), SO3 and water. However, NO2 molecule cannot react with the pre-adsorbed OH molecule and only physically adsorbed on the surface.

  8. Air–sea CO2 fluxes and the controls on ocean surface pCO2 variability in coastal and open-ocean southwestern Atlantic Ocean: a modeling study

    Directory of Open Access Journals (Sweden)

    R. Arruda

    2015-05-01

    Full Text Available We use an eddy-resolving, regional ocean biogeochemical model to investigate the main variables and processes responsible for the climatological spatio-temporal variability of pCO2 and the air–sea CO2 fluxes in the southwestern Atlantic Ocean. Overall, the region acts as sink of atmospheric CO2 south of 30° S, and is close to equilibrium with the atmospheric CO2 to the north. On the shelves, the ocean acts as a weak source of CO2, except for the mid/outer shelves of Patagonia, which act as sinks. In contrast, the inner shelves and the low latitude open ocean of the southwestern Atlantic represent source regions. Observed nearshore-to-offshore and meridional pCO2 gradients are well represented by our simulation. A sensitivity analysis shows the importance of the counteracting effects of temperature and dissolved inorganic carbon (DIC in controlling the seasonal variability of pCO2. Biological production and solubility are the main processes regulating pCO2, with biological production being particularly important on the shelf regions. The role of mixing/stratification in modulating DIC, and therefore surface pCO2 is shown in a vertical profile at the location of the Ocean Observatories Initiative (OOI site in the Argentine Basin (42° S, 42° W.

  9. 海洋微表层对海气CO2通量影响的研究进展%ADVANCES IN THE IMPACT OF SEA SURFACE MICROLAYER ON THE AIR-SEA CO2 FLUX

    Institute of Scientific and Technical Information of China (English)

    管玉平; 邢元明; 杨磊

    2012-01-01

    CO2的海气通量对于研究全球气候变化具有重要的意义.海洋微表层作为CO2在海洋和大气之间传输的重要通道,对于准确估算全球海气CO2通量的大小非常重要.本文主要从微表层中表面活性物质的富集,温度的偏低和与CO2的化学反应3个方面,综述了近年来与微表层相关的CO2通量研究进展,并对未来的相关研究进行了展望.%The research on air-sea CO2 flux is of great significance in researching the global climate change. As an vital channel of the transfer of CO2 between ocean and atmosphere, sea surface microlayer plays an important role in accurately estimating the air-sea CO2 flux. This paper mainly reviewed the progress of air-sea CO2 flux related with microlayer from three aspects i the enrichment of surfactant,the cool skin and chemical enhancement, and then took a preview of further research.

  10. Role of surface Ni and Ce species of Ni/CeO2 catalyst in CO2 methanation

    Science.gov (United States)

    Zhou, Guilin; Liu, Huiran; Cui, Kaikai; Jia, Aiping; Hu, Gengshen; Jiao, Zhaojie; Liu, Yunqi; Zhang, Xianming

    2016-10-01

    CeO2, which was used as support to prepare mesoporous Ni/CeO2 catalyst, was prepared by the hard-template method. The prepared NiO/CeO2 precursor and Ni/CeO2 catalyst were studied by H2-TPR, in-situ XPS, and in-situ FT-IR. The catalytic properties of the prepared Ni/CeO2 catalyst were also investigated by CO2 catalytic hydrogenation methanation. H2-TPR and in-situ XPS results showed that metal Ni species and surface oxygen vacancies could be formed by H2 reduction. In-situ FT-IR and in-situ XPS results indicated that CO2 molecules could be reduced by active metal Ni species and surface oxygen vacancies to generate active CO species and promote CO2 methanation. The Ni/CeO2 catalyst presented the high CO2 methanation activity, and CO2 conversion and CH4 selectivity reached 91.1% and 100% at 340 °C and atmospheric pressure.

  11. Surface-downhole and crosshole geoelectrics for monitoring of brine injection at the Ketzin CO2 storage site

    Science.gov (United States)

    Rippe, Dennis; Bergmann, Peter; Labitzke, Tim; Wagner, Florian; Schmidt-Hattenberger, Cornelia

    2016-04-01

    The Ketzin pilot site in Germany is the longest operating on-shore CO2 storage site in Europe. From June 2008 till August 2013, a total of ˜67,000 tonnes of CO2 were safely stored in a saline aquifer at depths of 630 m to 650 m. The storage site has now entered the abandonment phase, and continuation of the multi-disciplinary monitoring as part of the national project "CO2 post-injection monitoring and post-closure phase at the Ketzin pilot site" (COMPLETE) provides the unique chance to participate in the conclusion of the complete life cycle of a CO2 storage site. As part of the continuous evaluation of the functionality and integrity of the CO2 storage in Ketzin, from October 12, 2015 till January 6, 2015 a total of ˜2,900 tonnes of brine were successfully injected into the CO2 reservoir, hereby simulating in time-lapse the natural backflow of brine and the associated displacement of CO2. The main objectives of this brine injection experiment include investigation of how much of the CO2 in the pore space can be displaced by brine and if this displacement of CO2 during the brine injection differs from the displacement of formation fluid during the initial CO2 injection. Geophysical monitoring of the brine injection included continuous geoelectric measurements accompanied by monitoring of pressure and temperature conditions in the injection well and two adjacent observation wells. During the previous CO2 injection, the geoelectrical monitoring concept at the Ketzin pilot site consisted of permanent crosshole measurements and non-permanent large-scale surveys (Kiessling et al., 2010). Time-lapse geoelectrical tomographies derived from the weekly crosshole data at near-wellbore scale complemented by six surface-downhole surveys at a scale of 1.5 km showed a noticeable resistivity signature within the target storage zone, which was attributed to the CO2 plume (Schmidt-Hattenberger et al., 2011) and interpreted in terms of relative CO2 and brine saturations (Bergmann

  12. Shear bond, wettability and AFM evaluations on CO2 laser-irradiated CAD/CAM ceramic surfaces.

    Science.gov (United States)

    El Gamal, Ahmed; Medioni, Etienne; Rocca, Jean Paul; Fornaini, Carlo; Muhammad, Omid H; Brulat-Bouchard, Nathalie

    2017-03-09

    The purpose of this study is to determine the CO2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS), roughness (Rg) and wettability (Wt) of resin cement to CAD/CAM ceramics. Sixty (CAD/CAM) ceramic discs were prepared and distributed into six different groups: group A, control lithium disilicate (Li); group B, control zirconia (Zr); group C, Li: CO2/HF/Si; group D, Li: HF/Si; group E, Zr: CO2/Sb/Si; group F, Zr: Sb/Si. Result showed significant difference between irradiated and non-irradiated in terms of shear bond strength for zirconia ceramics (p value = 0.014). Moreover, partial surface wettability for irradiated and non-irradiated ceramics. Irradiated surface demonstrated more rough surface in lithium disilicate than zirconia ceramics. CO2 irradiation could increase shear bond strength, surface roughness and wettability for both CAD/CAM ceramics.

  13. Geomechanical modeling of surface uplift around well KB-502 at the in Salah CO2 storage site

    NARCIS (Netherlands)

    Fokker, P.A.; Orlic, B.; Meer, L.G.H. van der; Geel, C.R.

    2011-01-01

    Injection of CO2 in the InSalah field has caused uplift of the surface, as observed by satellite geodetic techniques (InSAR). Around one of the wells, KB-502, the uplift shows anomalous behaviour: a two-lobe pattern develops in the direction of the preferred fracture orientation. This indicates the

  14. Geomechanical modeling of surface uplift around well KB-502 at the in Salah CO2 storage site

    NARCIS (Netherlands)

    Fokker, P.A.; Orlic, B.; Meer, L.G.H. van der; Geel, C.R.

    2011-01-01

    Injection of CO2 in the InSalah field has caused uplift of the surface, as observed by satellite geodetic techniques (InSAR). Around one of the wells, KB-502, the uplift shows anomalous behaviour: a two-lobe pattern develops in the direction of the preferred fracture orientation. This indicates the

  15. Identifying Activity Descriptors for CO2 Electro-Reduction to Methanol on Rutile (110) Surfaces

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    Electrocatalytic reduction of CO2 to liquid fuels using energy from renewable sources has the potential to form the basis of a carbon neutral sustainable energy system, while integrating seamlessly in the established infrastructure1. Storing intermittent renewable energy in a chemical fuel...... is especially attractive to achieve high energy density required for transport applications. Among the metals, Cu electrocatalyst can convert CO2 to methane and ethylene in aqueous electrolytes at ambient temperature with moderate efficiency2. However, a high overpotential is required for this reaction...... reactivity enabling us to explore the reduction of CO2to methanol in a wide materials window. We use the computational hydrogen electrode model6 to calculate the potential dependent reaction free energies from density functional theory based calculations using BEEF-vdW functional and PAW method...

  16. Seasonal controls on surface pCO2 in the central and eastern Arabian Sea

    Indian Academy of Sciences (India)

    V V S S Sarma; M Dileep Kumar; M Gauns; M Madhupratap

    2000-12-01

    The variability in partial pressure of carbon dioxide (pCO2) and its control by biological and physical processes in the mixed layer (ML) of the central and eastern Arabian Sea during inter-monsoon, northeast monsoon, and southwest monsoon seasons were studied. The ML varied from 80-120 m during NE monsoon, 60-80 m and 20-30 m during SW- and inter-monsoon seasons, respectively, and the variability resulted from different physical processes. Significant seasonal variability was found in pCO2 levels. During SW monsoon, coastal waters contain two contrasting regimes; (a) pCO2 levels of 520-685 atm were observed in the SW coast of India, the highest found so far from this region, driven by intense upwelling and (b) low levels of pCO2 (266 atm) were found associated with monsoonal fresh water influx. It varied in ranges of 416-527 atm and 375-446 atm during inter- and NE monsoon, respectively, in coastal waters with higher values occurring in the north. The central Arabian Sea pCO2 levels were 351-433, 379-475 and 385-432 atm during NE- inter and SW monsoon seasons, respectively. The mixed layer pCO2 relations with temperature, oxygen, chlorophyll and primary production revealed that the former is largely regulated by physical processes during SW- and NE monsoon whereas both physical and biological processes are important in inter-monsoon. Application of Louanchi et al (1996) model revealed that the mixing effect is the dominant during monsoons, however, the biological effect is equally significant during SW monsoon whereas thermodynamics and fluxes influence during inter-monsoons.

  17. CO2 activation through silylimido and silylamido zirconium hydrides supported on N-donor chelating SBA15 surface ligand

    KAUST Repository

    Pasha, Fahran Ahmad

    2016-01-04

    Density functional theory calculations and 2D 1H-13C HETCOR solid state NMR spectroscopy prove that CO2 can probe, by its own reactivity, different types of N-donor surface ligands on SBA15-supported ZrIV hydrides: [(≡Si-O-)(≡Si-N=)[Zr]H] and [(≡Si-NH-)(≡Si-X-)[Zr]H2] (X = O or NH). Moreover, [(≡Si-O-)(≡Si-N=)[Zr]H] activates CO2 more efficiently than the other complexes and leads to a carbimato Zr formate.

  18. Landscape and Seasonal Variability in CO2 Efflux from Soil and Water Surfaces in the Northern Pantanal

    Science.gov (United States)

    Couto, E. G.; Pinto-Jr, O. B.; Lathuilliere, M. J.; Dalmagro, H. J.; Johnson, M. S.

    2014-12-01

    The Pantanal is one of the largest wetlands in the world, with an area of 150,000 km2. It extends over three countries (Brazil, Paraguay and Bolivia) with 80% located in the Brazilian states of Mato Grosso and Mato Grosso do Sul. Ecosystems in the Northern Pantanal rely on a seasonal flood pulse in phase with the wet season, which inundates grasslands and forests between January and May. This pulse results in an important change in local biogeochemistry. Inundation saturates the Pantanal's soils with changes in the balance of carbon dioxide and other greenhouse gases. This study summarize the main CO2 effluxes measured from a variety of landscape in the Northern Pantanal during dry and wet seasons, fully or partially inundated soils, as part of Project 2.01 of the Brazilian Institute for Science and Technology in Wetlands (Monitoring aquatic carbon fluxes and water quality). Using a network of dataloggers installed in 4 environments, we have been modeling soil CO2 efflux on a half hourly basis through a combination of infrared gas analyzers measurements and laboratory soil physical parameter estimates. The selected environments presented unique biogeochemical behavior as they relate to inundation and soil type. So far, we have estimated average CO2 efflux in 3 environments with mean values of 3.53 µmol m-2 s-1 (soil CO2 efflux for the "Carrapatal" tree island), 3.41 µmol m-2 s-1 (soil CO2 efflux for the "Baia das Pedras" tree island), and 1.79 µmol m-2 s-1 (aquatic CO2 evasion from the water surface of the "Cambarazal" flooded forest). More measurements are currently underway to complete the landscape variability in CO2 effluxes in the Northern Pantanal.

  19. Identifying Activity Descriptors for CO2 Electro-Reduction to Methanol on Rutile (110) Surfaces

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    towards electrocatalytic production of methanol. We would like to acknowledge the Lundbeck Foundation for financial support of this work. References: 1. Lewis, N. S. & Nocera, D. G. Powering the planet: chemical challenges in solar energy utilization. Proc. Natl. Acad. Sci. U. S. A.103,15729–35 (2006...... and almost no alcohols are produced. Experimental studies have shown that mixed rutile oxides (Ru/Ir/Ti) can catalyze the conversion of CO2 to alcohols3-5. However, very little is known about the reduction of CO2to alcohols on oxide electrocatalysts. Here, we present a computational study of the thermo...

  20. Development of Methods for Gaseous Phase Geochemical Monitoring on the Surface and in the Intermediate Overburden Strata of Geological CO2 Storage Sites Développement de méthodes de suivi géochimique en phase gazeuse à la surface et dans la couverture intermédiaire des sites de stockage géologique du CO2

    Directory of Open Access Journals (Sweden)

    Pokryszka Z.

    2010-03-01

    detecting and monitoring gas leaks through intermediate cap rock strata. This system will largely comprise conventional industrial gas sensors which are available off the shelf. The direct measurement of gas flows emanating from the ground is one of the most effective ways to monitor a storage site. The INERIS accumulation chamber method has been improved to measure low and very low CO2 flux rates. It can now be used to measure a wide range of CO2 flux rates, from very low emission levels of 0.05 to 0.2 cm3.min−1.m−2 up to extremely high flux rates of some 3000 cm3.min−1.m−2. The accuracy and operational characteristics of chamber method have been checked and validated by tests performed in a laboratory and on a test rig, as well as through field measurements taken under real conditions at sites that naturally release CO2. These tests have shown that the method has reached full technical maturity and that it can be applied on a practical level to detect and monitor CO2 and methane emissions on the ground’s surface. The two methods which have been tested are now operational and ready for integration into the surveillance strategy applied at future CO2 storage sites. They can be used at every stage of a storage site’s life: site reconnaissance, definition of the initial state, injection, post-injection phase, and residual monitoring after the site has been abandoned. Les développements et les résultats présentés sont issus des travaux réalisés dans le cadre du programme Géocarbone-Monitoring cofinancé par l’Agence Nationale de la Recherche (ANR. Une partie importante de ce programme a porté sur des méthodes de suivi géochimique en phase gazeuse à la surface et dans la couverture intermédiaire des sites de stockage géologique du CO2. Le travail effectué par l’INERIS a été ciblé sur deux approches particulières, souvent préconisées comme incontournables dans la surveillance des futurs sites de stockage : une détection précoce (pr

  1. Surface Reactivity of Iron Oxide Pigmentary Powders toward Atmospheric Components: XPS, FESEM, and Gravimetry of CO and CO2 Adsorption

    Science.gov (United States)

    Ismail; Cadenhead; Zaki

    1997-10-15

    The adsorption of carbon monoxide and carbon dioxide (CO and CO2) on a number of specially prepared alpha-Fe2O3 samples was measured gravimetrically at 25°C. The samples were prepared from a steel-pickling waste (97 wt% FeSO4·7H2O) by roasting the original material at 700°C for 5 h in air, oxygen, and nitrogen. Estimated surface coverages by the adsorbed CO and CO2 were made on the basis of nitrogen-adsorption-based surface areas, while the nature of the sample surfaces was investigated by both X-ray photoelectron spectroscopy (XPS) and field emission SEM (FESEM) techniques. In addition a depth profiling study utilizing a sputtering argon beam and XPS was undertaken. Morphological studies using FESEM showed that neither CO nor CO2 caused any significant structural changes. The nature of the resultant alpha-Fe2O3 sample surfaces differed, with the degree of oxygenation decreasing in the order of preparatory gases: oxygen, (wet) air, nitrogen [IP(O), IP(A), and IP(N)]. The amounts of both CO and CO2 adsorbed decreased in the sample order IP(A) > IP(O) > IP(N), though in the case of CO adsorption, the amounts adsorbed on IP(A) and IP(O) were not greatly different. In all cases the amounts adsorbed represented only fractional coverage. Adsorption of the more acidic CO2 is thought to be favored more by basic Ox-2 than by O2- sites on both IP(O) and IP(A), but with surface hydroxyl groups also playing a role (particularly on IP(A)). The CO2 adsorption should result in the formation of mono-, di-, and polydentate carbonate and bicarbonate species, with increasing degassing temperatures favoring the polydentate species and the decomposition of the bicarbonate and carbonate to form undissociated CO2. The adsorption of CO (a weak base) is postulated to take place on strong Lewis acid, highly coordinated, metal sites to form metal carbonyl species, on strong base sites (O2-) to form carbonite, oxalate, and ketenic species, and, to a lesser degree, on surface hydroxyl

  2. Enhancing CO2 electrolysis through synergistic control of non-stoichiometry and doping to tune cathode surface structures

    Science.gov (United States)

    Ye, Lingting; Zhang, Minyi; Huang, Ping; Guo, Guocong; Hong, Maochun; Li, Chunsen; Irvine, John T. S.; Xie, Kui

    2017-03-01

    Sustainable future energy scenarios require significant efficiency improvements in both electricity generation and storage. High-temperature solid oxide cells, and in particular carbon dioxide electrolysers, afford chemical storage of available electricity that can both stabilize and extend the utilization of renewables. Here we present a double doping strategy to facilitate CO2 reduction at perovskite titanate cathode surfaces, promoting adsorption/activation by making use of redox active dopants such as Mn linked to oxygen vacancies and dopants such as Ni that afford metal nanoparticle exsolution. Combined experimental characterization and first-principle calculations reveal that the adsorbed and activated CO2 adopts an intermediate chemical state between a carbon dioxide molecule and a carbonate ion. The dual doping strategy provides optimal performance with no degradation being observed after 100 h of high-temperature operation and 10 redox cycles, suggesting a reliable cathode material for CO2 electrolysis.

  3. Enhancing CO2 electrolysis through synergistic control of non-stoichiometry and doping to tune cathode surface structures

    Science.gov (United States)

    Ye, Lingting; Zhang, Minyi; Huang, Ping; Guo, Guocong; Hong, Maochun; Li, Chunsen; Irvine, John T. S.; Xie, Kui

    2017-01-01

    Sustainable future energy scenarios require significant efficiency improvements in both electricity generation and storage. High-temperature solid oxide cells, and in particular carbon dioxide electrolysers, afford chemical storage of available electricity that can both stabilize and extend the utilization of renewables. Here we present a double doping strategy to facilitate CO2 reduction at perovskite titanate cathode surfaces, promoting adsorption/activation by making use of redox active dopants such as Mn linked to oxygen vacancies and dopants such as Ni that afford metal nanoparticle exsolution. Combined experimental characterization and first-principle calculations reveal that the adsorbed and activated CO2 adopts an intermediate chemical state between a carbon dioxide molecule and a carbonate ion. The dual doping strategy provides optimal performance with no degradation being observed after 100 h of high-temperature operation and 10 redox cycles, suggesting a reliable cathode material for CO2 electrolysis. PMID:28300066

  4. The Effect of Carbon Dioxide (CO2) Laser on Sandblasting with Large Grit and Acid Etching (SLA) Surface.

    Science.gov (United States)

    Foroutan, Tahereh; Ayoubian, Nader

    2013-01-01

    The purpose of this study was to investigate the effect of 6W power Carbon Dioxide Laser (CO2) on the biologic compatibility of the Sandblasting with large grit and acid etching (SLA) titanium discs through studying of the Sarcoma Osteogenic (SaOS-2) human osteoblast-like cells viability. Sterilized titanium discs were used together with SaOS-2 human osteoblast-like cells. 6 sterilized SLA titanium discs of the experimental group were exposed to irradiation by CO2 laser with a power of 6W and 10.600nm wavelength, at fixed frequency of 80Hz during 45 seconds in both pulse and non-contact settings. SaOS-2 human osteoblast-like cells were incubated under 37°C in humid atmosphere (95% weather, 5% CO2) for 72 hours. MTT test was performed to measure the ratio level of cellular proliferation. The results indicated that at 570nm wavelength, the 6W CO2 laser power have not affected the cellular viability. CO2 laser in 6w power has had no effect on the biologic compatibility of the SLA titanium surface.

  5. [Optimization for supercritical CO2 extraction with response surface methodology and component analysis of Sapindus mukorossi oil].

    Science.gov (United States)

    Wu, Yan; Xiao, Xin-yu; Ge, Fa-huan

    2012-02-01

    To study the extraction conditions of Sapindus mukorossi oil by Supercritical CO2 Extraction and identify its components. Optimized SFE-CO2 Extraction by response surface methodology and used GC-MS to analysie Sapindus mukorossi oil compounds. Established the model of an equation for the extraction rate of Sapindus mukorossi oil by Supercritical CO2 Extraction, and the optimal parameters for the Supercritical CO2 Extraction determined by the equation were: the extraction pressure was 30 MPa, temperature was 40 degrees C; The separation I pressure was 14 MPa, temperature was 45 degrees C; The separation II pressure was 6 MPa, temperature was 40 degrees C; The extraction time was 60 min and the extraction rate of Sapindus mukorossi oil of 17.58%. 22 main compounds of Sapindus mukorossi oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 86.59%. This process is reliable, safe and with simple operation, and can be used for the extraction of Sapindus mukorossi oil.

  6. Optimal Surface Amino-Functionalization Following Thermo-Alkaline Treatment of Nanostructured Silica Adsorbents for Enhanced CO2 Adsorption

    Directory of Open Access Journals (Sweden)

    Obdulia Medina-Juárez

    2016-11-01

    Full Text Available Special preparation of Santa Barbara Amorphous (SBA-15, mesoporous silica with highly hexagonal ordered, these materials have been carried out for creating adsorbents exhibiting an enhanced and partially selective adsorption toward CO2. This creation starts from an adequate conditioning of the silica surface, via a thermo-alkaline treatment to increase the population of silanol species on it. CO2 adsorption is only reasonably achieved when the SiO2 surface becomes aminated after put in contact with a solution of an amino alkoxide compound in the right solvent. Unfunctionalized and amine-functionalized substrates were characterized through X-ray diffraction, N2 sorption, Raman spectroscopy, electron microscopy, 29Si solid-state Nuclear Magnetic Resonance (NMR, and NH3 thermal programmed desorption. These analyses proved that the thermo-alkaline procedure desilicates the substrate and eliminates the micropores (without affecting the SBA-15 capillaries, present in the original solid. NMR analysis confirms that the hydroxylated solid anchors more amino functionalizing molecules than the unhydroxylated material. The SBA-15 sample subjected to hydroxylation and amino-functionalization displays a high enthalpy of interaction, a reason why this solid is suitable for a strong deposition of CO2 but with the possibility of observing a low-pressure hysteresis phenomenon. Contrastingly, CH4 adsorption on amino-functionalized, hydroxylated SBA-15 substrates becomes almost five times lower than the CO2 one, thus giving proof of their selectivity toward CO2. Although the amount of retained CO2 is not yet similar to or higher than those determined in other investigations, the methodology herein described is still susceptible to optimization.

  7. Optimal Surface Amino-Functionalization Following Thermo-Alkaline Treatment of Nanostructured Silica Adsorbents for Enhanced CO2 Adsorption

    Science.gov (United States)

    Medina-Juárez, Obdulia; García-Sánchez, Miguel Ángel; Arellano-Sánchez, Ulises; Kornhauser-Straus, Isaac; Rojas-González, Fernando

    2016-01-01

    Special preparation of Santa Barbara Amorphous (SBA)-15, mesoporous silica with highly hexagonal ordered, these materials have been carried out for creating adsorbents exhibiting an enhanced and partially selective adsorption toward CO2. This creation starts from an adequate conditioning of the silica surface, via a thermo-alkaline treatment to increase the population of silanol species on it. CO2 adsorption is only reasonably achieved when the SiO2 surface becomes aminated after put in contact with a solution of an amino alkoxide compound in the right solvent. Unfunctionalized and amine-functionalized substrates were characterized through X-ray diffraction, N2 sorption, Raman spectroscopy, electron microscopy, 29Si solid-state Nuclear Magnetic Resonance (NMR), and NH3 thermal programmed desorption. These analyses proved that the thermo-alkaline procedure desilicates the substrate and eliminates the micropores (without affecting the SBA-15 capillaries), present in the original solid. NMR analysis confirms that the hydroxylated solid anchors more amino functionalizing molecules than the unhydroxylated material. The SBA-15 sample subjected to hydroxylation and amino-functionalization displays a high enthalpy of interaction, a reason why this solid is suitable for a strong deposition of CO2 but with the possibility of observing a low-pressure hysteresis phenomenon. Contrastingly, CH4 adsorption on amino-functionalized, hydroxylated SBA-15 substrates becomes almost five times lower than the CO2 one, thus giving proof of their selectivity toward CO2. Although the amount of retained CO2 is not yet similar to or higher than those determined in other investigations, the methodology herein described is still susceptible to optimization. PMID:28774017

  8. Surface Reaction Kinetics of Steam- and CO2-Reforming as Well as Oxidation of Methane over Nickel-Based Catalysts

    OpenAIRE

    Karla Herrera Delgado; Lubow Maier; Steffen Tischer; Alexander Zellner; Henning Stotz; Olaf Deutschmann

    2015-01-01

    An experimental and kinetic modeling study on the Ni-catalyzed conversion of methane under oxidative and reforming conditions is presented. The numerical model is based on a surface reaction mechanism consisting of 52 elementary-step like reactions with 14 surface and six gas-phase species. Reactions for the conversion of methane with oxygen, steam, and CO2 as well as methanation, water-gas shift reaction and carbon formation via Boudouard reaction are included. The mechanism is implemented i...

  9. Mechanisms influencing surface soil CO2 efflux in respect to elevation and vegetation gradients in a complex watershed

    Science.gov (United States)

    Atkins, J. W.; Epstein, H. E.; Welsch, D. L.

    2011-12-01

    Topographically complex watersheds exert spatial and temporal variations in the distribution of soil water due to horizontal flows. The redistribution of soil water has profound effects on biogeochemical cycles. Of keen interest is the impact this lateral redistribution has on carbon cycling and surface soil carbon efflux. We are currently employing a plot based study across an elevation gradient (950-1150 m) in the Weimer Run watershed located near Davis, West Virginia to evaluate carbon and water cycling dynamics. At each of three different elevation levels (high, middle, low) are three sites. At each site are three 4 m2 plots, each underneath a different vegetation cover type (open, closed tree canopy, shrub canopy), for a total of 27 plots across all elevations. At each plot, surface CO2 efflux, soil temperature, PAR, air temperature and volumetric soil water content at 0-12 cm are measured weekly during the growing season. Measurements of Leaf Area Index (LAI) and soil nutrient concentrations (NH4+, NO3-) have also been conducted for each plot. Each plot also has gas wells at both 5 and 20 cm to measure CO2 concentrations below the soil surface. Data collected from June through October, 2010, indicate a stronger control on soil CO2 efflux exerted by vegetation cover type than by elevation gradient. The impact of vegetation cover type on soil CO2 efflux increases with elevation. Based on data collected weekly from June through October, 2010, there is no significant relationship between surface soil CO2 efflux and the three elevation levels within our gradient (p = 0.47). However, a significant statistical relationship between surface soil CO2 efflux and vegetation type (p = impact that vegetation cover, elevation and micrometeorological controls exert on soil CO2 efflux is vital for accurate model inputs and carbon budgets.class="jpg" border=0 width=600px src="/meetings/fm11/program/tables/B33F-0525_T1.jpg"> * All values in columns represent means for

  10. Terminal sterilization of BisGMA-TEGDMA thermoset materials and their bioactive surfaces by supercritical CO2.

    Science.gov (United States)

    Donati, Ivan; Benincasa, Monica; Foulc, Marie-Pierre; Turco, Gianluca; Toppazzini, Mila; Solinas, Dario; Spilimbergo, Sara; Kikic, Ireneo; Paoletti, Sergio

    2012-04-09

    The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10(-6) must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO(2) (scCO(2)) in the presence of H(2)O(2) as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time-amount of H(2)O(2) relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by μCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H(2)O(2) induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO(2) led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO(2)-based terminal sterilization.

  11. CO2 Storage and Surface Flooding Process of Wu 38 Well Block in Yanchang Oilfield%延长油田吴38井区CO2埋存与驱油地面工艺

    Institute of Scientific and Technical Information of China (English)

    陈龙龙; 江绍静; 杨永超; 黄春霞; 余华贵; 白成来

    2016-01-01

    3 movable injection stations have been built in Wu38 well block of YanChang Oilfield. At the same time, five gas injection wells can be gas injected, which involving 24 production Wells. It is the first standardization surface process system that CO2 storage and CO2-EOR in the northwest.The system main body consists of two big modules:low pres-sure and high pressure. Low pressure module includes CO2 storage tank, CO2 feeding and circulation area, supercharging area; high-pressure module includes CO2 injection and loop area, auxiliary monitoring system. After the surface process system put into use, the single well CO2 injection rate is 25 t/d, it can realize automatic monitoring and data storage. Ac-cording to the forecast, the oil recovery of CO2 flooding is 10.79% higher than that of water flooding, which has the vital significance to the reduction of CO2 greenhouse gas emissions and low permeability reservoir development.%延长油田吴38井区已建成3座橇装式注入站,可同时对5口井实施注气,涉及24口生产井受效。它是西北第一个实施CO2埋存与驱油的标准化地面工艺系统,系统主体由低压及高压两大模块组成,低压模块包括CO2存储区、CO2喂液及循环区、增压区,高压模块包括CO2注入及循环区、辅助监测系统。地面工艺系统投入使用后,单井注入量为25 t/d,可实现数据全自动监控和存储。根据预测,原油采收率与水驱相比提高10.79%,这对减少CO2温室气体排放及低渗油藏开发具有重要的意义。

  12. Modelisations des effets de surface sur les jets horizontaux subsoniques d'hydrogene et de methane

    Science.gov (United States)

    Gomez, Luis Fernando

    Le developpement des codes et de normes bases sur une methodologie scientifique requiert la capacite de predire l'etendue inflammable de deversements gazeux d'hydrogene sous differentes conditions. Des etudes anterieures ont deja etabli des modeles bases sur les lois de conservation de la mecanique des fluides basees sur des correlations experimentales qui permettent de predire la decroissance de la concentration et de la vitesse d'un gaz le long de l'axe d'un jet libre vertical. Cette etude s'interesse aux effets de proximite a une surface horizontale parallele sur un jet turbulent. Nous nous interessons a son impact sur l'etendue du champ de la concentration et sur l'enveloppe inflammable en particulier. Cette etude est comparative : l'hydrogene est compare au methane. Ceci permet de degager l'influence des effets de difference de la densite sur le comportement du jet, et de comparer le comportement de l'hydrogene aux correlations experimentales, qui ont ete essentiellement etablies pour le methane. Un modele decrivant l'evolution spatio-temporelle du champ de concentration du gaz dilue est propose, base sur la mecanique des fluides computationnelle. Cette approche permet de varier systematiquement les conditions aux frontieres (proximite du jet a la surface, par exemple) et de connaitre en detail les proprietes de l'ecoulement. Le modele est implemente dans le code de simulations par volumes finis de FLUENT. Les resultats des simulations sont compares avec les lois de similitudes decoulant de la theorie des jets d'ecoulements turbulents libres ainsi qu'avec les resultats experimentaux disponibles. L'effet de la difference des masses molaires des constituantes du jet et des constituantes du milieu de dispersion est egalement etudie dans le contexte du comportement d'echelle de la region developpee du jet.

  13. Pembina Cardium CO2-EOR monitoring project: Integrated surface seismic and VSP time-lapse seismic analysis

    Science.gov (United States)

    Alshuhail, A. A.

    2009-12-01

    In the Pembina field in west-central Alberta, Canada, approximately 40,000 tons of supercritical CO2 was injected into the 1650 m deep, 20 m thick upper-Cretaceous Cardium Fm. between March 2005 and 2007. A time-lapse seismic program was designed and incorporated into the overall measurement, monitoring and verification program. The objectives were to track the CO2 plume within the reservoir, and to evaluate the integrity of storage. Fluid replacement modeling predicts a decrease in the P-wave velocity and bulk density in the reservoir by about 4% and 1%, respectively. Synthetic seismograms show subtle reflectivity changes at the Cardium Fm. and a traveltime delay at the later high-amplitude Viking event of less than 1 ms. The time-lapse datasets, however, show no significant anomalies in the P-wave seismic data that can be attributed to supercritical CO2 injected into the Cardium Fm. (Figure 1). The converted-wave (P-S) data, on the other hand, showed small traveltime anomalies. The most coherent results were those obtained by the fixed-array VSP dataset (Figure 2) due to higher frequency bandwidth and high signal to noise ratio. The amplitude and traveltime changes observed in the VSP dataset are small but are consistent in magnitude with those predicted from rock physics modeling. The analysis suggests that the inability to clearly detect the CO2 plume in surface seismic data is likely due to the CO2 being contained in thin permeable sandstone members of the Cardium Formation. The seismic signature of the Cardium Fm. in this area may also be degraded by multiples and strong attenuation involving the shallow Ardley coals. However, the lack of a 4D seismic changes above the reservoir indicates that the injected CO2 is not migrating through the caprock into shallower formations.

  14. Faraday efficiency and mechanism of electrochemical surface reactions: CO2 reduction and H2 formation on Pt(111).

    Science.gov (United States)

    Hussain, Javed; Jónsson, Hannes; Skúlason, Egill

    2016-12-22

    An atomic scale model of the electrical double layer is used to calculate the mechanism and rate of electrochemical reduction of CO2 as well as H2 formation at a Pt(111) electrode. The water layer contains solvated protons and the electrode has excess electrons at the surface. Density functional theory within the generalized gradient approximation is used to describe the electronic structure while the mechanism and activation energy of the various elementary reactions is obtained by calculating minimum energy paths using the nudged elastic band method. The applied electrical potential is deduced from the calculated work function. The optimal reaction mechanism for CO2 reduction to either methane or methanol is found and the estimated rate compared with that of the competing reaction, H2 formation. When the free energy of only the intermediates and reactants is taken into account, not the activation energy, Pt(111) would seem to be a good electrocatalyst for CO2 reduction, significantly better than Cu(111). This, however, contradicts experimental findings. Detailed calculations reported here show that the activation energy for CO2 reduction is high for both Heyrovsky and Tafel mechanisms on Pt(111) in the relevant range of applied potential. The rate-limiting step of the Heyrovsky mechanism, *COOH + H(+) + e(-) → *CO + H2O, is estimated to have an activation energy of 0.95 eV at -0.9 V vs. standard hydrogen electrode. Under the same conditions, the activation energy for H2 formation is estimated to be only 0.5 eV. This explains why attempts to reduce CO2 using platinum electrodes have produced only H2. A comparison is made with analogous results for Cu(111) [J. Hussain et al., Procedia Comput. Sci., 2015, 51, 1865] where a reaction mechanism with low activation energy for CO2 electroreduction to methane was identified. The difference between the two electrocatalysts is discussed.

  15. An In-Situ Root-Imaging System in the Context of Surface Detection of CO2

    Science.gov (United States)

    Apple, M. E.; Prince, J. B.; Bradley, A. R.; Zhou, X.; Lakkaraju, V. R.; Male, E. J.; Pickles, W.; Thordsen, J. J.; Dobeck, L.; Cunningham, A.; Spangler, L.

    2009-12-01

    Carbon sequestration is a valuable method of spatially confining CO2 belowground. The Zero Emissions Research Technology, (ZERT), site is an experimental facility in a former agricultural field on the Montana State University campus in Bozeman, Montana, where CO2 was experimentally released at a rate of 200kg/day in 2009 into a 100 meter underground injection well running parallel to the ground surface. This injection well, or pipe, has deliberate leaks at intervals, and CO2 travels from these leaks upward to the surface of the ground. The ZERT site is a model system designed with the purpose of testing methods of surface detection of CO2. One important aspect of surface detection is the determination of the effects of CO2 on the above and belowground portions of plants growing above sequestration fields. At ZERT, these plants consist of a pre-existing mixture of herbaceous species present at the agricultural field. Species growing at the ZERT site include several grasses, Dactylis glomerata (Orchard Grass), Poa pratensis (Kentucky Bluegrass), and Bromus japonicus (Japanese Brome); the nitrogen-fixing legumes Medicago sativa, (Alfalfa), and Lotus corniculatus, (Birdsfoot trefoil); and an abundance of Taraxacum officinale, (Dandelion). Although the aboveground parts of the plants at high CO2 are stressed, as indicated by changes in hyperspectral plant signatures, leaf fluorescence and leaf chlorophyll content, we are interested in determining whether the roots are also stressed. To do so, we are combining measurements of soil conductivity and soil moisture with root imaging. We are using an in-situ root-imaging system manufactured by CID, Inc. (Camas, WA), along with image analysis software (Image-J) to analyze morphometric parameters in the images and to determine what effects, if any, the presence of leaking and subsequently upwelling CO2 has on the phenology of root growth, growth and turnover of individual fine and coarse roots, branching patterns, and root

  16. Microleakage in Class V Composite Restorations after Desensitizing Surface Treatment with Er:YAG and CO2 Lasers.

    Science.gov (United States)

    Mozaffari, Hamid Reza; Ehteshami, Alireza; Zallaghi, Farshad; Chiniforush, Nasim; Moradi, Zohreh

    2016-12-30

    Aims: Glutaraldehyde, CO2 and Er:YAG lasers can be used for treatment of dentin hypersensitivity. However, their application may have adverse effects on the clinical service of restorations. This study aimed to assess the microleakage in composite restorations following surface treatment with Glutaraldehyde desensitizer, CO2 and Er:YAG laser irradiation for treatment of dentin hypersensitivity. Materials and methods: This experimental study was conducted on 60 extracted sound human teeth. Class V cavities were prepared measuring 3×3 mm using a diamond bur. Specimens were randomly divided into 4 groups of 15. Group one:no surface treatment, Group two:applying Glutaraldehyde desensitizer, Groups of three and four were irradiated with CO2 and Er:YAG lasers, respectively. Surfaces were restored with bonding agent (Single Bond 2, 3M, USA) and Z250 composite (3M, USA). Specimens were thermocycled and immersed in 1% methylene blue solution for 24 hours. Microleakage scores were assessed under a stereomicroscope at ×20 magnification. Data were analyzed using SPSS and the Kruskal Wallis test (P=0.05). Results: There was no significant difference between microleakage of groups in enamel margins (P=0.694). The difference in microleakage at the dentin margin was significant between groups (P=0.018). Conclusions: Application of Glutaraldehyde-desensitizer and CO2 laser irradiation of surfaces prior to composite restoration do not increase microleakage at the enamel or dentin margins but tooth surface treatment with Er:YAG laser significantly increased the microleakage at the dentin margins.

  17. Surface Reaction Kinetics of Steam- and CO2-Reforming as Well as Oxidation of Methane over Nickel-Based Catalysts

    Directory of Open Access Journals (Sweden)

    Karla Herrera Delgado

    2015-05-01

    Full Text Available An experimental and kinetic modeling study on the Ni-catalyzed conversion of methane under oxidative and reforming conditions is presented. The numerical model is based on a surface reaction mechanism consisting of 52 elementary-step like reactions with 14 surface and six gas-phase species. Reactions for the conversion of methane with oxygen, steam, and CO2 as well as methanation, water-gas shift reaction and carbon formation via Boudouard reaction are included. The mechanism is implemented in a one-dimensional flow field description of a fixed bed reactor. The model is evaluated by comparison of numerical simulations with data derived from isothermal experiments in a flow reactor over a powdered nickel-based catalyst using varying inlet gas compositions and operating temperatures. Furthermore, the influence of hydrogen and water as co-feed on methane dry reforming with CO2 is also investigated.

  18. Rotationally Induced Surface Slope-Instabilities and the Activation of CO2 Activity on Comet 103P/Hartley 2

    CERN Document Server

    Steckloff, Jordan K; Hirabayashi, Toshi; Melosh, H Jay; Richardson, James

    2016-01-01

    Comet 103P/Hartley 2 has diurnally controlled, CO2-driven activity on the tip of the small lobe of its bilobate nucleus. Such activity is unique among the comet nuclei visited by spacecraft, and suggests that CO2 ice is very near the surface, which is inconsistent with our expectations of an object that thermophysically evolved for ~45 million years prior to entering the Jupiter Family of comets. Here we explain this pattern of activity by showing that a very plausible recent episode of rapid rotation (rotation period of ~11 [10-13] hours) would have induced avalanches in Hartley 2's currently active regions that excavated down to CO2-rich ices and activated the small lobe of the nucleus. At Hartley 2's current rate of spindown about its principal axis, the nucleus would have been spinning fast enough to induce avalanches ~3-4 orbits prior to the DIXI flyby (~1984-1991). This coincides with Hartley 2's discovery in 1986, and implies that the initiation of CO2 activity facilitated the comet's discovery. During...

  19. Preliminary results of continuous GPS monitoring of surface deformation at the Aquistore underground CO2 storage site

    Science.gov (United States)

    Craymer, M. R.; Henton, J. A.; Piraszewski, M.; Silliker, J.; Samsonov, S. V.

    2013-12-01

    Aquistore is a demonstration project for the underground storage of CO2 at a depth of ~3350 m near Estevan, Saskatchewan, Canada. An objective of the project is to design, adapt, and test non-seismic monitoring methods that have not been systematically utilized to date for monitoring CO2 storage projects, and to integrate the data from these various monitoring tools to obtain quantitative estimates of the change in subsurface fluid distributions, pressure changes and associated surface deformation. Monitoring methods being applied include satellite-, surface- and wellbore-based monitoring systems and comprise natural- and controlled-source electromagnetic methods, gravity monitoring, GPS, synthetic aperture radar interferometry (InSAR), tiltmeter array analysis, and chemical tracer studies. Here we focus on the GPS monitoring of surface deformation. Five of the planned thirteen GPS monitoring stations were installed in November 2012 and results subsequently processed on a weekly basis. The first GPS results prior to CO2 injection have just been determined using both precise point positioning (PPP) and baseline processing with the Bernese GPS Software. The time series of the five sites are examined, compared and analysed with respect to monument stability, seasonal signals and estimates of expected regional ground motion. The individual weekly network solutions are combined together in a cumulative 4D network solution to provide a preliminary local velocity field in the immediately vicinity of the injection well. The results are compared to those from InSAR.

  20. Promotional effect of surface hydroxyls on electrochemical reduction of CO2 over SnOx/Sn electrode

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chaonan; Han, Jinyu; Zhu, Xinli; Liu, Xiao; Wang, Hua; Mei, Donghai; Ge, Qingfeng

    2016-11-01

    Tin oxide (SnOx) formation on tin-based electrode surfaces during CO2 electrochemical reduction can have a significant impact on the activity and selectivity of the reaction. In the present study, density functional theory (DFT) calculations have been performed to understand the role of SnOx in CO2 reduction using a SnO monolayer on the Sn(112) surface as a model for SnOx. Water molecules have been treated explicitly and considered actively participating in the reaction. The results showed that H2O dissociates on the perfect SnO monolayer into two hydroxyl groups symmetrically on the surface. CO2 energetically prefers to react with the hydroxyl, forming a bicarbonate (HCO3(t)*) intermediate, which can then be reduced to either formate (HCOO*) by hydrogenating the carbon atom or carboxyl (COOH*) by protonating the oxygen atom. Both steps involve a simultaneous C-O bond breaking. Further reduction of HCOO* species leads to the formation of formic acid in the acidic solution at pH < 4, while the COOH* will decompose to CO and H2O via protonation. Whereas the oxygen vacancy (VO) in the monolayer maybe formed by the reduction of the monolayer, it can be recovered by H2O dissociation, resulting in two embedded hydroxyl groups. However, the hydroxylated surface with two symmetric hydroxyls is energetically more favorable for CO2 reduction than the hydroxylated VO surface with two embedded hydroxyls. The reduction potential for the former has a limiting-potential of -0.20 V (RHE), lower than that for the latter (-0.74 V (RHE)). Compared to the pure Sn electrode, the formation of SnOx monolayer on the electrode under the operating conditions promotes CO2 reduction more effectively by forming surface hydroxyls, thereby, providing a new channel via COOH* to the CO formation, although formic acid is still the major reduction product. The work was supported in part by National Natural Sciences Foundation of China (Grant #21373148 and #21206117). The High Performance Computing

  1. Half-metallic properties of the Co 2Ti 1- xFe xGa Heusler alloys and Co 2Ti 0.5Fe 0.5Ga (0 0 1) surface

    Science.gov (United States)

    Ahmadian, F.; Boochani, A.

    2011-07-01

    Electronic and magnetic properties of the bulk Co 2Ti 1- xFe xGa Heusler alloys and Co 2Ti 0.5Fe 0.5Ga (0 0 1) surfaces are studied within the framework of density functional theory using the augmented plane wave plus local orbital (APW+lo) approach. It will be shown that all alloys have the spin polarization of the ideal 100% value except the Co 2FeGa alloy with spin polarization about 98%. Co 2Ti 0.5Fe 0.5Ga is an example that is stable against the effects destroying the half-metallicity due to the position of the Fermi energy ( EF) in the middle of the minority band gap. The phase diagram obtained by ab-initio atomistic thermodynamics shows that in the higher limit of μGa three surfaces of FeGa, TiGa and TiFeGa are accessible in the Co 2Ti 0.5Fe 0.5Ga alloy but on decreasing μGa, the accessible region gradually moves towards FeGa termination. It is discussed that, at the ideal surfaces, half-metallicity of the alloy is lost, although the TiGa surface keeps high spin polarization (about 95%).

  2. Impact of hydrogeological and geomechanical properties on surface uplift at a CO2 injection site: Parameter estimation and uncertainty quantification

    Science.gov (United States)

    Newell, P.; Yoon, H.; Martinez, M. J.; Bishop, J. E.; Arnold, B. W.; Bryant, S.

    2013-12-01

    It is essential to couple multiphase flow and geomechanical response in order to predict a consequence of geological storage of CO2. In this study, we estimate key hydrogeologic features to govern the geomechanical response (i.e., surface uplift) at a large-scale CO2 injection project at In Salah, Algeria using the Sierra Toolkit - a multi-physics simulation code developed at Sandia National Laboratories. Importantly, a jointed rock model is used to study the effect of postulated fractures in the injection zone on the surface uplift. The In Salah Gas Project includes an industrial-scale demonstration of CO2 storage in an active gas field where CO2 from natural gas production is being re-injected into a brine-filled portion of the structure downdip of the gas accumulation. The observed data include millimeter scale surface deformations (e.g., uplift) reported in the literature and injection well locations and rate histories provided by the operators. Our preliminary results show that the intrinsic permeability and Biot coefficient of the injection zone are important. Moreover pre-existing fractures within the injection zone affect the uplift significantly. Estimation of additional (i.e., anisotropy ratio) and coupled parameters will help us to develop models, which account for the complex relationship between mechanical integrity and CO2 injection-induced pressure changes. Uncertainty quantification of model predictions will be also performed using various algorithms including null-space Monte Carlo and polynomial-chaos expansion methods. This work will highlight that our coupled reservoir and geomechanical simulations associated with parameter estimation can provide a practical solution for designing operating conditions and understanding subsurface processes associated with the CO2 injection. This work is supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office

  3. A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, Lee H.; Dobeck, Laura M.; Repasky, Kevin S.; Nehrir, Amin R.; Humphries, Seth D.; Barr, Jamie L.; Keith, Charlie J.; Shaw, Joseph A.; Rouse, Joshua H.; Cunningham, Alfred B.; Benson, Sally M.; Oldenburg, Curtis M.; Lewicki, Jennifer L.; Wells, Arthur W.; Diehl, J. R.; Strazisar, Brian; Fessenden, Julianna; Rahn, Thom A.; Amonette, James E.; Barr, Jonathan L.; Pickles, William L.; Jacobson, James D.; Silver, Eli A.; Male, Erin J.; Rauch, Henry W.; Gullickson, Kadie; Trautz, Robert; Kharaka, Yousif; Birkholzer, Jens; Wielopolski, Lucien

    2010-03-01

    A facility has been constructed to perform controlled shallow releases of CO2 at flow rates that challenge near surface detection techniques and can be scalable to desired retention rates of large scale CO2 storage projects. Preinjection measurements were made to determine background conditions and characterize natural variability at the site. Modeling of CO2 transport and concentration in saturated soil and the vadose zone was also performed to inform decisions about CO2 release rates and sampling strategies. Four releases of CO2 were carried out over the summer field seasons of 2007 and 2008. Transport of CO2 through soil, water, plants, and air was studied using near surface detection techniques. Soil CO2 flux, soil gas concentration, total carbon in soil, water chemistry, plant health, net CO2 flux, atmospheric CO2 concentration, movement of tracers, and stable isotope ratios were among the quantities measured. Even at relatively low fluxes, most techniques were able to detect elevated levels of CO2 in the soil, atmosphere, or water. Plant stress induced by CO2 was detectable above natural seasonal variations.

  4. Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency

    Science.gov (United States)

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A.

    2012-07-01

    Tremendous interest exists towards synthesizing nanoassemblies for dye-sensitized solar cells (DSSCs) using earth-abundant and -friendly materials with green synthetic approaches. In this work, high surface area TiO2 nanowire arrays were grown on the surface of functionalized graphene sheets (FGSs) containing -COOH functionalities acting as a template by using a sol-gel method in the green solvent, supercritical carbon dioxide (scCO2). The effect of scCO2 pressure (1500, 3000 and 5000 psi), temperature (40, 60 and 80 °C), acetic acid/titanium isopropoxide monomer ratios (HAc/TIP = 2, 4 and 6), functionalized graphene sheets (FGSs)/TIP weight ratios (1:20, 1:40 and 1:60 w/w) and solvents (EtOH, hexane) were investigated. Increasing the HAc/TIPweight ratio from 4 to 6 in scCO2 resulted in increasing the TiO2 nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO2 with the -COOH groups on the surface of the graphene sheets, indicating that graphene acted as a template for polycondensation growth. UV-vis diffuse reflectance and photoluminescence spectroscopy showed a reduction in titania’s bandgap and also a significant reduction in electron-hole recombination compared to bare TiO2 nanowires. Photocurrent measurements showed that the TiO2nanowire/graphene composites prepared in scCO2 gave a 5× enhancement in photoefficiency compared to bare TiO2 nanowires.

  5. Model Selection Coupled with a Particle Tracking Proxy Using Surface Deformation Data for Monitoring CO2 Plume Migration

    Science.gov (United States)

    Min, B.; Nwachukwu, A.; Srinivasan, S.; Wheeler, M. F.

    2015-12-01

    This study formulates a framework of a model selection that refines geological models for monitoring CO2 plume migration. Special emphasis is placed on CO2 injection, and the particular techniques that are used for this study including model selection, particle tracking proxies, and partial coupling of flow and geomechanics. The proposed process starts with generating a large initial ensemble of reservoir models that reflect a prior uncertainty in reservoir description, including all plausible geologic scenarios. These models are presumed to be conditioned to available static data. In the absence of production or injection data, all prior reservoir models are regarded as equiprobable. Thus, the model selection algorithm is applied to select a few representative reservoir models that are more consistent with observed dynamic responses. A quick assessment of the models must then be performed to evaluate their dynamic characteristics and flow connectivity. This approach develops a particle tracking proxy and a finite element method solver for solving the flow equation and the stress problem, respectively. The shape of CO2 plume is estimated using a particle-tracking proxy that serves as a fast approximation of finite-difference simulation models. Sequentially, a finite element method solver is coupled with the proxy for analyzing geomechanical effects resulting from CO2 injection. A method is then implemented to group the models into clusters based on similarities in the estimated responses. The posterior model set is chosen as the cluster that produces the minimum deviation from the observed field data. The efficacy of non-dominated sorting based on Pareto-optimality is also tested in the current model selection framework. The proposed scheme is demonstrated on a carbon sequestration project in Algeria. Coupling surface deformation data with well injection data enhances the efficiency of tracking the CO2 plume. Therefore, this algorithm provides a probabilistic

  6. Evidence from simultaneous intracellular- and surface-pH transients that carbonic anhydrase IV enhances CO2 fluxes across Xenopus oocyte plasma membranes.

    Science.gov (United States)

    Musa-Aziz, Raif; Occhipinti, Rossana; Boron, Walter F

    2014-11-01

    Human carbonic anhydrase IV (CA IV) is GPI-anchored to the outer membrane surface, catalyzing CO2/HCO3 (-) hydration-dehydration. We examined effects of heterologously expressed CA IV on intracellular-pH (pHi) and surface-pH (pHS) transients caused by exposing oocytes to CO2/HCO3 (-)/pH 7.50. CO2 influx causes a sustained pHi fall and a transient pHS rise; CO2 efflux does the opposite. Both during CO2 addition and removal, CA IV increases magnitudes of maximal rate of pHi change (dpHi/dt)max, and maximal pHS change (ΔpHS) and decreases time constants for pHi changes (τpHi ) and pHS relaxations (τpHS ). Decreases in time constants indicate that CA IV enhances CO2 fluxes. Extracellular acetazolamide blocks all CA IV effects, but not those of injected CA II. Injected acetazolamide partially reduces CA IV effects. Thus, extracellular CA is required for, and the equivalent of cytosol-accessible CA augments, the effects of CA IV. Increasing the concentration of the extracellular non-CO2/HCO3 (-) buffer (i.e., HEPES), in the presence of extracellular CA or at high [CO2], accelerates CO2 influx. Simultaneous measurements with two pHS electrodes, one on the oocyte meridian perpendicular to the axis of flow and one downstream from the direction of extracellular-solution flow, reveal that the downstream electrode has a larger (i.e., slower) τpHS , indicating [CO2] asymmetry over the oocyte surface. A reaction-diffusion mathematical model (third paper in series) accounts for the above general features, and supports the conclusion that extracellular CA, which replenishes entering CO2 or consumes exiting CO2 at the extracellular surface, enhances the gradient driving CO2 influx across the cell membrane.

  7. Feasibility of Seismic Monitoring at a Potential CO2 Injection Test Site in the Paris Basin Évaluation des apports de la sismique à la surveillance d’un test d’injection de CO2 sur un site pilote potentiel du Bassin de Paris

    Directory of Open Access Journals (Sweden)

    Becquey M.

    2009-09-01

    Full Text Available Seismic effects of the injection of CO2 into a partially depleted oil field have been evaluated. Seismic modelling yields small time-lapse effects, including 0.4 ms time-shifts and 4 to 6% amplitude variations at the top and bottom of the reservoir. Amplitude variations at the reservoir level should be slightly larger at large incidence angles, but wave equation modelling shows that picking these reflections will not be easy, because of the presence of shear waves generated at upper interfaces. In-situ fracturation generates azimuthal anisotropy with velocity and amplitude variations with the propagation direction. These variations bear some information about the crack density, about the relation between the fracture nets and the porous medium, and about the fluid content in the pores and fractures. All these effects are however weak and their measurement requires careful seismic data acquisition and processing. Les effets sismiques de l’injection de dioxyde de carbone dans un gisement de petrole deplete ont fait l’objet d’une simulation. Ces effets sont faibles. On peut s’attendre a une variation des temps d’arrivee des reflexions sur des interfaces situees en dessous des reservoirs, de l’ordre de la demi-milliseconde, et a une variation d’amplitude au toit et au mur du reservoir de l’ordre de 6 %. La variation d’amplitude sera legerement plus forte pour les reflexions a grand deport, mais le pointe des reflexions et la mesure des amplitudes seront probablement plus difficiles, en raison de la presence d’ondes converties. La mesure de l’anisotropie azimutale, due a la presence de fractures, peut nous donner des informations sur l’etat de fracturation du reservoir et sur la connexion entre ces fractures et la matrice poreuse. La mesure de ces variations subtiles necessitera une acquisition soignee et un traitement precautionneux des donnees.

  8. Surface-reconstructed Cu Electrode via a Facile Electrochemical Anodization-Reduction Process for Low Overpotential CO 2 reduction

    KAUST Repository

    Min, Shixiong

    2017-03-21

    A high-surface-area Cu electrode, fabricated by a simple electrochemical anodization-reduction method, exhibits high activity and selectivity for CO2 reduction at low overpotential in 0.1 M KHCO3 solution. A faradaic efficiency of 37% for HCOOH and 27% for CO production was achieved with the current density of 1.5 mA cm-2 at −0.64 V vs. RHE, much higher than that of polycrystalline Cu. The enhanced catalytic performance is a result of the formation of the high electrochemical active surface area and high density of preferred low-index facets.

  9. Biogenic CO2 fluxes, changes in surface albedo and biodiversity impacts from establishment of a miscanthus plantation

    DEFF Research Database (Denmark)

    Jørgensen, Susanne Vedel; Cherubini, Francesco; Michelsen, Ottar

    2014-01-01

    Depletion in oil resources and environmental concern related to the use of fossil fuels has increased the interest in using second generation biomass as alternative feedstock for fuels and materials. However, the land use and land use change for producing second generation (2G) biomass impacts...... the environment in various ways, of which not all are usually considered in life cycle assessment.This study assesses the biogenic CO2 fluxes, surface albedo changes and biodiversity impacts for 100 years after changing land use from forest or fallow land to miscanthus plantation in Wisconsin, US. Climate change...... human influenced state to another.Concerning the impacts from biogenic CO2 fluxes, in the case of conversion from a forest to a miscanthus plantation (case A) there is a contribution to global warming, whereas when a fallow land is converted (case B), there is a climate cooling. When the effects from...

  10. LIBS Sensor for Sub-surface CO2 Leak Detection in Carbon Sequestration

    Directory of Open Access Journals (Sweden)

    Jinesh JAIN

    2017-07-01

    Full Text Available Monitoring carbon sequestration poses numerous challenges to the sensor community. For example, the subsurface environment is notoriously harsh, with large potential mechanical, thermal, and chemical stresses, making long-term stability and survival a challenge to any potential in situ monitoring method. Laser induced breakdown spectroscopy (LIBS has been demonstrated as a promising technology for chemical monitoring of harsh environments and hard to reach places. LIBS has a real- time monitoring capability and can be used for the elemental and isotopic analysis of solid, liquid, and gas samples. The flexibility of the probe design and the use of fiber- optics has made LIBS particularly suited for remote measurements. The paper focuses on developing a LIBS instrument for downhole high-pressure, high-temperature brine experiments, where CO2 leakage could result in changes in the trace mineral composition of an aquifer. The progress in fabricating a compact, robust, and simple LIBS sensor for widespread subsurface leak detection is presented.

  11. Data-based estimates of the ocean carbon sink variability – first results of the Surface Ocean pCO2 Mapping intercomparison (SOCOM

    Directory of Open Access Journals (Sweden)

    C. Rödenbeck

    2015-08-01

    Full Text Available Using measurements of the surface-ocean CO2 partial pressure (pCO2 and 14 different pCO2 mapping methods recently collated by the Surface Ocean pCO2 Mapping intercomparison (SOCOM initiative, variations in regional and global sea–air CO2 fluxes have been investigated. Though the available mapping methods use widely different approaches, we find relatively consistent estimates of regional pCO2 seasonality, in line with previous estimates. In terms of interannual variability (IAV, all mapping methods estimate the largest variations to occur in the Eastern equatorial Pacific. Despite considerable spead in the detailed variations, mapping methods with closer match to the data also tend to be more consistent with each other. Encouragingly, this includes mapping methods belonging to complementary types – taking variability either directly from the pCO2 data or indirectly from driver data via regression. From a weighted ensemble average, we find an IAV amplitude of the global sea–air CO2 flux of 0.31 PgC yr−1 (standard deviation over 1992–2009, which is larger than simulated by biogeochemical process models. On a decadal perspective, the global CO2 uptake is estimated to have gradually increased since about 2000, with little decadal change prior to 2000. The weighted mean total ocean CO2 sink estimated by the SOCOM ensemble is consistent within uncertainties with estimates from ocean-interior carbon data or atmospheric oxygen trends.

  12. Spontaneous activation of CO2 and corrosion pathways on iron surface Fe(100): a quantum mechanical study informed by DFT-based dynamics

    Science.gov (United States)

    Glezakou, V. A.; McGrail, P.; Dang, L. X.

    2009-12-01

    Because of the rapidly increasing interest in technologies for capturing and permanently sequestering CO2 as part of a climate change mitigation strategy, understanding the interaction of CO2 with materials that comprise a sequestration system (steels, cements, silicate minerals, etc.) is of fundamental importance. The majority of models for corrosion of metals involve water-mediated processes, with CO2 dissolved in the aqueous phase playing a minor role in the process. In contrast, recent experiments with mild steels have shown that much greater corrosivity actually occurs in the dense CO2 phase, provided sufficient molecular water is present in the CO2 phase to catalyse certain reactions. In our study, we use DFT-based dynamics to study the internal structure of the the super-critical CO2/(H2O)n system, with n=0-4. While water does not disturb the super-critical CO2 phase, it also gives rise to short-lived CO2...H2O bonds which are likely to facilitate the activation of CO2 on the surface, but otherwise maintains its molecular form. We also use DFT methods to probe the fundamental interactions of CO2 or SO2 and H2O with clean or doped iron surfaces and determine the reactive pathways that lead to CO2 chemisorption, dissociation and further formation of corrosion products in the form of carbonates or sulfites. DFT-based molecular dynamics are employed to sample the configurational space of reactants and products more efficiently. CO2 adsorbs readily on the surface assuming a bent geometry, indicative of charge transfer from the surface to CO2, which closely resembles a CO2- moiety. Once CO2 is adsorbed, it can decompose to adsorbed O+CO, which further reacts with CO2 or SO2 to form corrosion products. Molecularly adsorbed water acts as catalyst to lower these reaction barriers. Clearly, the reactive pathways on the surface are quite different than those in aqueous solution. Battelle operates Pacific Northwest National Laboratory for the US Department of Energy.

  13. First Results of Continuous GPS Monitoring of Surface Deformation at the Aquistore Underground CO2 Storage Site

    Science.gov (United States)

    Craymer, M. R.; Ferland, R.; Piraszewski, M.; Samsonov, S. V.; Czarnogorska, M.

    2014-12-01

    Aquistore is a demonstration project for the underground storage of CO2 at a depth of ~3350 m near Estevan, Saskatchewan, Canada. An objective of the project is to design, adapt, and test non-seismic monitoring methods that have not been systematically utilized to date for monitoring CO2 storage projects, and to integrate the data from these various monitoring tools to obtain quantitative estimates of the change in subsurface fluid distributions, pressure changes and associated surface deformation. Monitoring methods being applied include satellite-, surface- and wellbore-based monitoring systems and comprise natural- and controlled-source electromagnetic methods, gravity monitoring, GPS, synthetic aperture radar interferometry (InSAR), tiltmeter array analysis, and chemical tracer studies. Here we focus on the GPS monitoring of surface deformation. Five GPS monitoring stations were installed in 2012 and another six in 2013, some collocated on top of InSAR retroreflectors. The GPS data from these stations have been processed on a weekly basis in both baseline processing mode using the Bernese GPS Software and precise point positioning mode using CSRS-PPP. Here we present the first complete results with 1-2 years of data at all sites prior to CO2 injection. The time series of these sites are examined, compared and analysed with respect to monument stability, seasonal signals and estimates of expected regional ground motion. The individual weekly network solutions have also been combined together in a cumulative 4D network solution to provide a preliminary local velocity field in the immediately vicinity of the injection well. These results are also compared to those obtained independently from InSAR, in particular the direct comparison of GPS and InSAR at the retroreflectors.

  14. A first principles study of interactions of CO2 with surfaces of a Cu(benzene-1,3,5-tricarboxylate) metal organic framework

    Science.gov (United States)

    Li, Jie; Zhu, Chenming; Qiao, Zhen; Chen, Xinqing; Wei, Wei; Ji, Haifeng; Sohlberg, Karl

    2016-11-01

    Density functional theory is used to investigate the interaction of CO2 with the 100 and 010 surfaces of a Cu(benzene 1,3,5 tricarboxylate) metal organic framework. The calculation method is first validated by applying it to similar systems for which reliable results have been reported in literature and verifying that consistent results are obtained. The method is then applied to the Cu(benzene 1,3,5 tricarboxylate) system. The results show that neither the 100 or 010 surface undergoes major surface relaxation or surface reconstruction during structural optimization. CO2 adsorption calculations show that on the 100 surface, the CO2 molecule interacts with the surface benzene ring through π-π interaction. On the 010 surface, the interaction between the CO2 and the surface is again dominated by dispersion. Population analysis shows that a Cu atom on the 010 surface, even when nominally coordinatively unsaturated, is not electron deficient, which explains why CO2 does not bind to it chemically. Adsorption of multiple CO2 molecules on the 100 surface was also studied to investigate the dependence of the interaction on surface coverage. Least squares fitting of experimental adsorption versus pressure data to the BET isotherm model yields a binding energy in good agreement with the first-principles calculations.

  15. Effect of cw-CO2 laser surface treatment on structure and properties of AZ91 magnesium alloy

    Science.gov (United States)

    Iwaszko, Józef; Strzelecka, Monika

    2016-06-01

    In the study, samples of AZ91 magnesium alloy were subjected to a surface remelting treatment by means of a continuous wave (cw) CO2 laser. The scope of the investigation included both macro- and microstructural examination, hardness measurements, and wear resistance tests. The investigation has shown that remelting treatment leads to a strong refinement of structure in the surface layer and a more even distribution of phases. Fine α-phase dendrites have been observed to dominate in the remelting zone. The dendritic arm spacing in the laser treated surface was in the range of 1-2.5 μm. The structural changes triggered by remelting have contributed to an increase in the hardness and the wear resistance of AZ91 alloy. The microhardness of the remelted zone has increased to 71-93 HV0.05 for single-strip remelting and to 84-107 HV0.05 for multi-strip remelting in comparison with about ~60 HV0.05 for untreated alloy. The friction coefficient has decreased from 0.375 for material w/o treatment to 0.311 for remelted material. SEM investigations of samples after tribological tests have revealed the presence of parallel grooves proving the occurrence of microploughing and micro cutting of the material during the tribological testing. The results of the conducted investigation have indicated a beneficial influence of the cw-CO2 laser remelting treatment on the structure and properties of AZ91 alloy.

  16. EXPERIMENTAL DESIGN AND RESPONSE SURFACE MODELING OF PI/PES-ZEOLITE 4A MIXED MATRIX MEMBRANE FOR CO2 SEPARATION

    Directory of Open Access Journals (Sweden)

    T. D. KUSWORO

    2015-09-01

    Full Text Available This paper investigates the effect of preparation of polyimide/polyethersulfone (PI/PES blending-zeolite mixed matrix membrane through the manipulation of membrane production variables such as polymer concentration, blending composition and zeolite loading. Combination of central composite design and response surface methodology were applied to determine the main effect and interaction effects of these variables on membrane separation performance. The quadratic models between each response and the independent parameters were developed and the response surface models were tested with analysis of variance (ANOVA. In this study, PI/ (PES–zeolite 4A mixed matrix membranes were casted using dry/wet phase inversion technique. The separation performance of mixed matrix membrane had been tested using pure gases such as CO2 and CH4. The results showed that zeolite loading was the most significant variable that influenced the CO2/CH4 selectivity among three variables and the experimental results were in good agreement with those predicted by the proposed regression models. The gas separation performance of the membrane was relatively higher as compare to polymeric membrane. Therefore, combination of central composite design and response surface methodology can be used to prepare optimal condition for mixed matrix membrane fabrication. The incorporation of 20 wt% zeolite 4A into 25 wt% of PI/PES matrix had resulted in a high separation performance of membrane material.

  17. Relation between Cutting Surface Quality and Alloying Element Contents when Using a CO2 Laser

    Directory of Open Access Journals (Sweden)

    J. Litecká

    2011-01-01

    Full Text Available This paper deals with the influence of material content on changes in the quality parameters of the cutting surface when cutting with a laser. The study focuses on experiments to find the effect of material structure and cutting parameters on surface roughness, Vickers microhardness and precision of laser cutting. The experimental results are shown in graphs which illustrate the suitability of materials for achieving required cutting surface quality parameters. These results can be used for optimizing production in practical applications using a laser cutting machine.

  18. The influence of vegetation and relief heterogeneity on turbulent exchange of CO2 between land surface and the atmosphere

    Science.gov (United States)

    Mukhartova, Juliya; Levashova, Natalia; Volkova, Elena; Olchev, Alexander

    2016-04-01

    The possible effect of spatial heterogeneity of vegetation cover and relief on horizontal and vertical turbulent exchange of CO2 was described using a process-based two-dimensional (2D) turbulent exchange models (Mukhartova et al. 2015). As a key area for this modeling study the hilly territory situated at the boundary between broadleaf forest and steppe zones in European part of Russia (Tula region) was selected. The vegetation cover in the study region is represented by complex mosaic of crop areas, grasslands, pastures, mires and groves. The very heterogeneous vegetation cover and complex dissected relief make very difficult an adequate determining the local and regional CO2 fluxes using experimental methods only. The two-dimensional model based on solution of the Navier-Stokes and continuity equations using well-known one-and-a-half order (TKE) closure scheme is applied. For description of the plant canopy photosynthesis and respiration rates the model uses an aggregated approach based on the model of Ball et al (1987) in Leuning modification (1990, 1995), the Beer-Lambert equation for the description of solar radiation penetration within a plant canopy (Monsi, Saeki 1953), and also an algorithm describing the response of stomatal conductance of the leaves to incoming photosynthetically active radiation. All necessary input parameters describing the photosynthesis and respiration properties of different plants and soil types in the study region were measured in the field or taken from the literature. The system of differential equations in the model is numerically solved by the finite-difference method. It is assumed that the influence of ground surface heterogeneities at the upper boundary of computing domain is very low and the pressure excess can be therefore considered as zero. The concentration of CO2 at the upper boundary of computing domain is assumed to be equal to some background value. It is also assumed that all boundaries between different

  19. CO2 mitigation by carbon nanotube formation during dry reforming of methane analyzed by factorial design combined with response surface methodology

    Institute of Scientific and Technical Information of China (English)

    Tiago P. Braga; Regina C. R. Santos; Barbara M. C. Sales; Bruno R. da Silva; Antônio N. Pinheiro; Edson R. Leite; Antoninho Valentini

    2014-01-01

    A factorial experimental design was combined with response surface methodology (RSM) to opti-mize the catalyzed CO2 consumption by coke deposition and syngas production during the dry re-forming of CH4. The CH4/CO2 feed ratio and the reaction temperature were chosen as the variables, and the selected responses were CH4 and CO2 conversion, the H2/CO ratio, and coke deposition. The optimal reaction conditions were found to be a CH4/CO2 feed ratio of approximately 3 at 700 °C, producing a large quantity of coke and realizing high CO2 conversion. Furthermore, Raman results showed that the CH4/CO2 ratio and reaction temperature affect the system’s response, particularly the characteristics of the coke produced, which indicates the formation of carbon nanotubes and amorphous carbon.

  20. Structure Effects on the Energetics of the Electrochemical Reduction of CO2 by Copper Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Durand, William

    2011-08-19

    Polycrystalline copper electrocatalysts have been experimentally shown to be capable of reducing CO{sub 2} into CH{sub 4} and C{sub 2}H{sub 4} with relatively high selectivity, and a mechanism has recently been proposed for this reduction on the fcc(211) surface of copper, which was assumed to be the most active facet. In the current work, we use computational methods to explore the effects of the nanostructure of the copper surface and compare the effects of the fcc(111), fcc(100) and fcc(211) facets of copper on the energetics of the electroreduction of CO{sub 2}. The calculations performed in this study generally show that the intermediates in CO{sub 2} reduction are most stabilized by the (211) facet, followed by the (100) facet, with the (111) surface binding the adsorbates most weakly. This leads to the prediction that the (211) facet is the most active surface among the three in producing CH{sub 4} from CO{sub 2}, as well as the by-products H{sub 2} and CO. HCOOH production may be mildly enhanced on the more close-packed surfaces ((111) and (100)) as compared to the (211) facet, due to a change in mechanism from a carboxyl intermediate to a formate intermediate. The results are compared to experimental data on these same surfaces; the predicted trends in voltage requirements are consistent between the experimental and computational data.

  1. Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions

    Directory of Open Access Journals (Sweden)

    A. Babenhauserheide

    2015-03-01

    Full Text Available Data assimilation systems allow for estimating surface fluxes of greenhouse gases from atmospheric concentration measurements. Good knowledge about fluxes is essential to understand how climate change affects ecosystems and to characterize feedback mechanisms. Based on assimilation of more than one year of atmospheric in-situ concentration measurements, we compare the performance of two established data assimilation models, CarbonTracker and TM5-4DVar, for CO2 flux estimation. CarbonTracker uses an Ensemble Kalman Filter method to optimize fluxes on ecoregions. TM5-4DVar employs a 4-D variational method and optimizes fluxes on a 6° × 4° longitude/latitude grid. Harmonizing the input data allows analyzing the strengths and weaknesses of the two approaches by direct comparison of the modelled concentrations and the estimated fluxes. We further assess the sensitivity of the two approaches to the density of observations and operational parameters such as temporal and spatial correlation lengths. Our results show that both models provide optimized CO2 concentration fields of similar quality. In Antarctica CarbonTracker underestimates the wintertime CO2 concentrations, since its 5-week assimilation window does not allow for adjusting the far-away surface fluxes in response to the detected concentration mismatch. Flux estimates by CarbonTracker and TM5-4DVar are consistent and robust for regions with good observation coverage, regions with low observation coverage reveal significant differences. In South America, the fluxes estimated by TM5-4DVar suffer from limited representativeness of the few observations. For the North American continent, mimicking the historical increase of measurement network density shows improving agreement between CarbonTracker and TM5-4DVar flux estimates for increasing observation density.

  2. Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions

    Directory of Open Access Journals (Sweden)

    A. Babenhauserheide

    2015-09-01

    Full Text Available Data assimilation systems allow for estimating surface fluxes of greenhouse gases from atmospheric concentration measurements. Good knowledge about fluxes is essential to understand how climate change affects ecosystems and to characterize feedback mechanisms. Based on the assimilation of more than 1 year of atmospheric in situ concentration measurements, we compare the performance of two established data assimilation models, CarbonTracker and TM5-4DVar (Transport Model 5 – Four-Dimensional Variational model, for CO2 flux estimation. CarbonTracker uses an ensemble Kalman filter method to optimize fluxes on ecoregions. TM5-4DVar employs a 4-D variational method and optimizes fluxes on a 6° × 4° longitude–latitude grid. Harmonizing the input data allows for analyzing the strengths and weaknesses of the two approaches by direct comparison of the modeled concentrations and the estimated fluxes. We further assess the sensitivity of the two approaches to the density of observations and operational parameters such as the length of the assimilation time window. Our results show that both models provide optimized CO2 concentration fields of similar quality. In Antarctica CarbonTracker underestimates the wintertime CO2 concentrations, since its 5-week assimilation window does not allow for adjusting the distant surface fluxes in response to the detected concentration mismatch. Flux estimates by CarbonTracker and TM5-4DVar are consistent and robust for regions with good observation coverage, regions with low observation coverage reveal significant differences. In South America, the fluxes estimated by TM5-4DVar suffer from limited representativeness of the few observations. For the North American continent, mimicking the historical increase of the measurement network density shows improving agreement between CarbonTracker and TM5-4DVar flux estimates for increasing observation density.

  3. Full Aperture CO2 Laser Process to Improve Laser Damage Resistance of Fused Silica Optical Surface

    Directory of Open Access Journals (Sweden)

    Wei Liao

    2014-01-01

    Full Text Available An improved method is presented to scan the full-aperture optical surface rapidly by using galvanometer steering mirrors. In contrast to the previous studies, the scanning velocity is faster by several orders of magnitude. The velocity is chosen to allow little thermodeposition thus providing small and uniform residual stress. An appropriate power density is set to obtain a lower processing temperature. The proper parameters can help to prevent optical surface from fracturing during operation at high laser flux. S-on-1 damage test results show that the damage threshold of scanned area is approximately 40% higher than that of untreated area.

  4. An update to the Surface Ocean CO2 Atlas (SOCAT version 2)

    Digital Repository Service at National Institute of Oceanography (India)

    Bakker, D.C.E; Hankin, S.; Olsen, A; Pfeil, B; Smith, K.; Alin, S.R.; Cosca, C; Hales, B.; Harasawa, S.; Kozyr, A.; Nojiri, Y.; OBrien, K.M.; Schuster, U.; Telszewski, M.; Tilbrook, B.; Wada, C.; Akl, J.; Barbero, L.; Bates, N.; Boutin, J.; Cai, W.J.; Castle, R.D.; Chavez, F.; Chen, L.; Chierici, M.; Currie, K.; Evans, W.; Feely, R.A.; Fransson, A.; Gao, Z.; Hardman-Mountford, N.; Hoppema, M.; Huang, W.J.; Hunt, C.W.; Huss, B.; Ichikawa, T.; Jacobson, A.; Johannessen, T.; Jones, E.M.; Jones, S.; Sara, J.; Kitidis, V.; Kortzinger, A.; Lauvset, S.; Lefevre, N.; Manke, A.B; Mathis, J.; Metzl, N.; Monteiro, P.; Murata, A.; Newberger, T.; Nobuo, T.; Ono, T.; Paterson, K.; Pierrot, D.; Rios, A.F.; Sabine, C.L.; Saito, S.; Salisbury, J.; Sarma, V.V.S.S.; Schlitzer, R.; Sieger, R.; Skjelvan, I.; Steinhoff, T.; Sullivan, K.; Sutherland, S.C.; Suzuki, T.; Sutton, A.; Sweeney, C.; Takahashi, T.; Tjiputra, J.; VanHeuven, S.; Vandemark, D.; Vlahos, P.; Wallace, D.W.R.; Wanninkhof, R.; Watson, A.J.

    of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO2 values) and extended data coverage (from 1968–2007 to 1968–2011). The quality control criteria, while...

  5. A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, L.H.; Dobeck, L.M.; Nehrir, A.; Humphries, S.; Barr, J.; Keith, C.; Shaw, J.; Rouse, J.; Cunningham, A.; Benson, S.; Repasky, K.S.; Lewicki, J.; Wells, A.; Diehl, R.; Strazisar, B.; Fessenden, J.; Rahn, T.; Amonette, J.; Barr, J.; Pickles, W.; Jacobson, J.; Silver, E.; Male, E.; Rauch, H.; Gullickson, K.; Trautz, R.; Kharaka, Y.; Birkholzer, J.T.; Wielopolski, L.; Oldenburg, C.M.

    2009-10-20

    A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO2 transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO2 release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO2 transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO2 from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO2 through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented.

  6. A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

    Science.gov (United States)

    Spangler, L.H.; Dobeck, L.M.; Repasky, K.S.; Nehrir, A.R.; Humphries, S.D.; Keith, C.J.; Shaw, J.A.; Rouse, J.H.; Cunningham, A.B.; Benson, S.M.; Oldenburg, C.M.; Lewicki, J.L.; Wells, A.W.; Diehl, J.R.; Strazisar, B.R.; Fessenden, J.E.; Rahn, T.A.; Amonette, J.E.; Barr, J.L.; Pickles, W.L.; Jacobson, J.D.; Silver, E.A.; Male, E.J.; Rauch, H.W.; Gullickson, K.S.; Trautz, R.; Kharaka, Y.; Birkholzer, J.; Wielopolski, L.

    2010-01-01

    A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO2 transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO2 release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO2 transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO2 from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO2 through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented. ?? 2009 The Author(s).

  7. Estimating temporal and spatial variation of ocean surface pCO2 in the North Pacific using a self-organizing map neural network technique

    Directory of Open Access Journals (Sweden)

    S. Nakaoka

    2013-09-01

    Full Text Available This study uses a neural network technique to produce maps of the partial pressure of oceanic carbon dioxide (pCO2sea in the North Pacific on a 0.25° latitude × 0.25° longitude grid from 2002 to 2008. The pCO2sea distribution was computed using a self-organizing map (SOM originally utilized to map the pCO2sea in the North Atlantic. Four proxy parameters – sea surface temperature (SST, mixed layer depth, chlorophyll a concentration, and sea surface salinity (SSS – are used during the training phase to enable the network to resolve the nonlinear relationships between the pCO2sea distribution and biogeochemistry of the basin. The observed pCO2sea data were obtained from an extensive dataset generated by the volunteer observation ship program operated by the National Institute for Environmental Studies (NIES. The reconstructed pCO2sea values agreed well with the pCO2sea measurements, with the root-mean-square error ranging from 17.6 μatm (for the NIES dataset used in the SOM to 20.2 μatm (for independent dataset. We confirmed that the pCO2sea estimates could be improved by including SSS as one of the training parameters and by taking into account secular increases of pCO2sea that have tracked increases in atmospheric CO2. Estimated pCO2sea values accurately reproduced pCO2sea data at several time series locations in the North Pacific. The distributions of pCO2sea revealed by 7 yr averaged monthly pCO2sea maps were similar to Lamont-Doherty Earth Observatory pCO2sea climatology, allowing, however, for a more detailed analysis of biogeochemical conditions. The distributions of pCO2sea anomalies over the North Pacific during the winter clearly showed regional contrasts between El Niño and La Niña years related to changes of SST and vertical mixing.

  8. Sensitivity of Venus surface emissivity retrieval to model variations of CO2 opacity, cloud features, and deep atmosphere temperature field

    Science.gov (United States)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2012-07-01

    The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express space probe has acquired a wealth of nightside emission spectra from Venus and provides the first global database for systematic atmospheric and surface studies in the IR. The infrared mapping channel (VIRTIS-M-IR) sounds the atmosphere and surface at high spatial and temporal resolution and coverage. Quantitative analyses of data call for a sophisticated radiative transfer simulation model of Venus' atmosphere to be used in atmospheric and surface parameter retrieval procedures that fit simulated spectra to the measured data. The surface emissivity can be retrieved from VIRTIS-M-IR measurements in the transparency windows around 1 μm, but it is not easy to derive, since atmospheric influences strongly interfere with surface information. There are mainly three atmospheric model parameters that may affect quantitative results of surface emissivity retrievals: CO_2 opacity, cloud features, and deep atmosphere temperature field. The CO_2 opacity with respect to allowed transitions is usually computed by utilizing a suitable line data base and certain line shape models that consider collisional line mixing. Both line data bases and shape models are not well established from measurements under the environmental conditions in the deep atmosphere of Venus. Pressure-induced additional continuum absorption introduces further opacity uncertainties. The clouds of Venus are usually modeled by a four-modal distribution of spherical droplets of about 75% sulfuric acid, where each mode is characterized by a different mean and standard deviation of droplet size distribution and a different initial altitude abundance profile. The influence of possible cloud mode variations on surface emissivity retrieval results is investigated in the paper. Future retrieval procedures will aim at a separation of cloud mode and surface emissivity variations using different atmospheric windows sounded by

  9. Study of CO2 laser smoothing of surface roughness in fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Shen, N; Matthews, J; Fair, J E; Britten, J A; Nguyen, H T; Cooke, D; Elhadj, S; Henshaw, D; Guss, G M; Guss, G M; Yang, T

    2009-11-03

    Small micrometer-sized roughness on optical surfaces, caused by laser damage and/or redeposition of laser ablated material, can cause local electric field intensification which may lead to damage initiation both on the optics and/or downstream. We examined the smoothing of etched periodic surface structures on SiO{sub 2} substrate with 10.6 {micro}m CO{sub 2} laser using atomic force microscopy. The characteristic surface tension driven mass flow of the glass under different laser parameters were simulated using computational fluid dynamics and correlated with experimental results. We found that during CO{sub 2} laser polishing the estimate viscosity of the silica glass appears to be higher than typical literature values measured at a temperature similar to the laser heating conditions. This discrepancy can be explained by the observation that at high temperature, a significant portion of the hydroxyl content in the layer of heated silica glass can diffuse out resulting in a much stiffer glass.

  10. Biogenic CO2 fluxes, changes in surface albedo and biodiversity impacts from establishment of a miscanthus plantation.

    Science.gov (United States)

    Jørgensen, Susanne V; Cherubini, Francesco; Michelsen, Ottar

    2014-12-15

    Depletion in oil resources and environmental concern related to the use of fossil fuels has increased the interest in using second generation biomass as alternative feedstock for fuels and materials. However, the land use and land use change for producing second generation (2G) biomass impacts the environment in various ways, of which not all are usually considered in life cycle assessment. This study assesses the biogenic CO2 fluxes, surface albedo changes and biodiversity impacts for 100 years after changing land use from forest or fallow land to miscanthus plantation in Wisconsin, US. Climate change impacts are addressed in terms of effective forcing, a mid-point indicator which can be used to compare impacts from biogenic CO2 fluxes and albedo changes. Biodiversity impacts are assessed through elaboration on two different existing approaches, to express the change in biodiversity impact from one human influenced state to another. Concerning the impacts from biogenic CO2 fluxes, in the case of conversion from a forest to a miscanthus plantation (case A) there is a contribution to global warming, whereas when a fallow land is converted (case B), there is a climate cooling. When the effects from albedo changes are included, both scenarios show a net cooling impact, which is more pronounced in case B. Both cases reduce biodiversity in the area where the miscanthus plantation is established, though most in case A. The results illustrate the relevance of these issues when considering environmental impacts of land use and land use change. The apparent trade-offs in terms of environmental impacts further highlight the importance of including these aspects in LCA of land use and land use changes, in order to enable informed decision making.

  11. Surface Pressure Dependencies in the GEOS-Chem-Adjoint System and the Impact of the GEOS-5 Surface Pressure on CO2 Model Forecast

    Science.gov (United States)

    Lee, Meemong; Weidner, Richard

    2016-01-01

    In the GEOS-Chem Adjoint (GCA) system, the total (wet) surface pressure of the GEOS meteorology is employed as dry surface pressure, ignoring the presence of water vapor. The Jet Propulsion Laboratory (JPL) Carbon Monitoring System (CMS) research team has been evaluating the impact of the above discrepancy on the CO2 model forecast and the CO2 flux inversion. The JPL CMS research utilizes a multi-mission assimilation framework developed by the Multi-Mission Observation Operator (M2O2) research team at JPL extending the GCA system. The GCA-M2O2 framework facilitates mission-generic 3D and 4D-variational assimilations streamlining the interfaces to the satellite data products and prior emission inventories. The GCA-M2O2 framework currently integrates the GCA system version 35h and provides a dry surface pressure setup to allow the CO2 model forecast to be performed with the GEOS-5 surface pressure directly or after converting it to dry surface pressure.

  12. Pressurization Risk Assessment of CO2 Reservoirs Utilizing Design of Experiments and Response Surface Methods

    Science.gov (United States)

    Guyant, E.; Han, W. S.; Kim, K. Y.; Park, E.; Han, K.

    2015-12-01

    Monitoring of pressure buildup can provide explicit information on reservoir integrity and is an appealing tool, however pressure variation is dependent on a variety of factors causing high uncertainty in pressure predictions. This work evaluated pressurization of a reservoir system in the presence of leakage pathways as well as exploring the effects of compartmentalization of the reservoir utilizing design of experiments (Definitive Screening, Box Behnken, Central Composite, and Latin Hypercube designs) and response surface methods. Two models were developed, 1) an idealized injection scenario in order to evaluate the performance of multiple designs, and 2) a complex injection scenario implementing the best performing design to investigate pressurization of the reservoir system. A holistic evaluation of scenario 1, determined that the Central Composite design would be used for the complex injection scenario. The complex scenario evaluated 5 risk factors: reservoir, seal, leakage pathway and fault permeabilities, and horizontal position of the pathway. A total of 60 response surface models (RSM) were developed for the complex scenario with an average R2 of 0.95 and a NRMSE of 0.067. Sensitivity to the input factors was dynamic through space and time; at the earliest time (0.05 years) the reservoir permeability was dominant, and for later times (>0.5 years) the fault permeability became dominant for all locations. The RSM's were then used to conduct a Monte Carlo Analysis to further analyze pressurization risks, identifying the P10, P50, P90 values. This identified the in zone (lower) P90 values as 2.16, 1.77, and 1.53 MPa and above zone values of 1.35, 1.23, 1.09 MPa for monitoring locations 1, 2, and 3, respectively. In summary, the design of experiments and response surface methods allowed for an efficient sensitivity and uncertainty analysis to be conducted permitting a complete evaluation of the pressurization across the entire parameter space.

  13. Effects of Microporosity and Surface Chemistry on Separation Performances of N-Containing Pitch-Based Activated Carbons for CO2/N2 Binary Mixture

    Science.gov (United States)

    Lee, Min-Sang; Park, Mira; Kim, Hak Yong; Park, Soo-Jin

    2016-03-01

    In this study, N-containing pitch-based activated carbons (NPCs) were prepared using petroleum pitch with a low softening point and melamine with a high nitrogen content. The major advantage of the preparation method is that it enables variations in chemical structures and textural properties by steam activation at high temperatures. The adequate micropore structures, appropriate chemical modifications, and high adsorption enthalpies of NPCs are favorable for CO2 adsorption onto carbon surfaces. Furthermore, the structure generates a considerable gas/N-containing carbon interfacial area, and provides selective access to CO2 molecules over N2 molecules by offering an increased number of active sites on the carbon surfaces. The highest CO2/N2 selectivity, i.e., 47.5, and CO2 adsorption capacity for a CO2/N2 (0.15:0.85) binary gas mixture, i.e., 5.30 wt%, were attained at 298 K. The NPCs also gave reversible and durable CO2-capturing performances. All the results suggest that NPCs are promising CO2 sorbents, which can meet the challenges of current CO2 capture and separation techniques.

  14. Effects of Microporosity and Surface Chemistry on Separation Performances of N-Containing Pitch-Based Activated Carbons for CO2/N2 Binary Mixture

    Science.gov (United States)

    Lee, Min-Sang; Park, Mira; Kim, Hak Yong; Park, Soo-Jin

    2016-01-01

    In this study, N-containing pitch-based activated carbons (NPCs) were prepared using petroleum pitch with a low softening point and melamine with a high nitrogen content. The major advantage of the preparation method is that it enables variations in chemical structures and textural properties by steam activation at high temperatures. The adequate micropore structures, appropriate chemical modifications, and high adsorption enthalpies of NPCs are favorable for CO2 adsorption onto carbon surfaces. Furthermore, the structure generates a considerable gas/N-containing carbon interfacial area, and provides selective access to CO2 molecules over N2 molecules by offering an increased number of active sites on the carbon surfaces. The highest CO2/N2 selectivity, i.e., 47.5, and CO2 adsorption capacity for a CO2/N2 (0.15:0.85) binary gas mixture, i.e., 5.30 wt%, were attained at 298 K. The NPCs also gave reversible and durable CO2-capturing performances. All the results suggest that NPCs are promising CO2 sorbents, which can meet the challenges of current CO2 capture and separation techniques. PMID:26987683

  15. Variability in pH, fCO 2, oxygen and flux of CO 2 in the surface water along a transect in the Atlantic sector of the Southern Ocean

    Science.gov (United States)

    Chierici, Melissa; Fransson, Agneta; Turner, David R.; Pakhomov, E. A.; Froneman, P. W.

    2004-11-01

    Underway sampling and measurements of pH, fCO 2, oxygen and Chlorophyll a (Chl a) were performed in the surface waters from Cape Town (South Africa) to Queen Maud Land (Antarctica) in the Atlantic sector of the Southern Ocean during the austral summer 1997/1998. From direct measurements of these parameters and from calculated fCO 2 the oceanic carbon dioxide system was studied and related to hydrological and biological parameters. fCO 2 was in general undersaturated relative to the atmosphere and showed a large variability with values ranging from 313 to 377 μatm with a mean value of 346±13 μatm. The undersaturation was more pronounced in areas associated with fronts where high Chl a and high pH in situ values were observed. Using shipboard wind speed data, estimates of the CO 2 flux were made along the transect and during three mesoscale surveys on the northward return transect in the area of the Spring Ice Edge (SIE), the Winter Ice Edge (WIE) and in the Antarctic Polar Front (APF). The undersaturation observed during the transect caused the ocean to act as a sink for CO 2 with a mean sea-air flux for the entire transect of -3±5 mmol m -2 d -1 with a large variability between -20 mmol m -2 d -1 (oceanic uptake) to 1.3 mmol m -2 d -1 (oceanic source). The lowest fCO 2 values (largest oceanic uptake of CO 2) were found at the southern boundary of the APF at 53°S, which coincided with a supersaturation in oxygen and high pH values. Oxygen concentrations were measured from 50°S to 63°S and varied between 324 and 359 μmol kg -1 with a mean value of 347±9 μmol kg -1. In general only small deviations from equilibrium oxygen saturation were observed (mean value=99±2%). However, in the SIE oxygen was clearly undersaturated, probably an effect of upwelling of oxygen poor deep water which had not yet been compensated for by biological production. Three weeks later, the ice edge had retreated in the SIE region and the Chl a concentration had increased three

  16. Modelling regional scale surface fluxes, meteorology and CO2 mixing ratios for the Cabauw tower in the Netherlands

    NARCIS (Netherlands)

    Tolk, L. F.; Peters, W.; Meesters, A. G. C. A.; Groenendijk, M.; Vermeulen, A. T.; Steeneveld, G. J.; Dolman, A. J.

    2009-01-01

    We simulated meteorology and atmospheric CO2 transport over the Netherlands with the mesoscale model RAMS-Leaf3 coupled to the biospheric CO2 flux model 5PM. The results were compared with meteorological and CO2 observations, with emphasis on the tall tower of Cabauw. An analysis of the coupled exch

  17. [Optimization of supercritical CO2 extraction of plantaginis semen oil by response surface methodology and studies on its antioxidant activity].

    Science.gov (United States)

    Xu, Wei; Ling, Weijian; Chu, Kedan; Li, Huang; Chen, Lidian; Zhang, Yuqin; Chen, Xianwen

    2011-12-01

    The optimum conditions of SFE-CO2 extraction of Plantaginis Semen oil (SPO), the composition of SPO and its antioxidant activities of SPO were all investigated in this paper. Response surface method (RSM) was used to establish the mathematical model of SFE-CO2 extraction of SPO to obtain the optimum conditions based on Single factor experiments. Fatty acid compositions and contents of SPO were tested by GC-MS, and antioxidant activities of SPO were studied by DPPH and ABTS free radical elimination method. The optimum conditions obtained through RSM analysis were as follows: extraction tempreture 70 degrees C, extraction pressure 30 MPa, extraction time 120 min and flow rate 30 L x h(-1). Under the optimal condition, predicted value was 35.91%, while the experimental value was 35.07%. The experimental values agree with the predicted from the regression model with a relative error less than 5%. The main components of SPO were 9,12,15-octadecatrienoic acid, 8,11-octadecadienoic acid, octadecanoic acid and hexadecanoic acid. Most of the fatty acids were polyunsaturated fatty ones, whose quantities were obtained more than 88%. The IC50DPPH and IC50ABTS were 1.13, 3.57 g x L(-1) respectively in DPPH and ABTS assay. Optimization of the extraction process by RSM of SPO is convenient and feasible. SPO has good antioxidant activity and is worth to develop for application.

  18. Biofilm-like properties of the sea surface and predicted effects on air-sea CO2 exchange

    Science.gov (United States)

    Wurl, Oliver; Stolle, Christian; Van Thuoc, Chu; The Thu, Pham; Mari, Xavier

    2016-05-01

    Because the sea surface controls various interactions between the ocean and the atmosphere, it has a profound function for marine biogeochemistry and climate regulation. The sea surface is the gateway for the exchange of climate-relevant gases, heat and particles. Thus, in order to determine how the ocean and the atmosphere interact and respond to environmental changes on a global scale, the characterization and understanding of the sea surface are essential. The uppermost part of the water column is defined as the sea-surface microlayer and experiences strong spatial and temporal dynamics, mainly due to meteorological forcing. Wave-damped areas at the sea surface are caused by the accumulation of surface-active organic material and are defined as slicks. Natural slicks are observed frequently but their biogeochemical properties are poorly understood. In the present study, we found up to 40 times more transparent exopolymer particles (TEP), the foundation of any biofilm, in slicks compared to the underlying bulk water at multiple stations in the North Pacific, South China Sea, and Baltic Sea. We found a significant lower enrichment of TEP (up to 6) in non-slick sea surfaces compared to its underlying bulk water. Moreover, slicks were characterized by a large microbial biomass, another shared feature with conventional biofilms on solid surfaces. Compared to non-slick samples (avg. pairwise similarity of 70%), the community composition of bacteria in slicks was increasingly (avg. pairwise similarity of 45%) different from bulk water communities, indicating that the TEP-matrix creates specific environments for its inhabitants. We, therefore, conclude that slicks can feature biofilm-like properties with the excessive accumulation of particles and microbes. We also assessed the potential distribution and frequency of slick-formation in coastal and oceanic regions, and their effect on air-sea CO2 exchange based on literature data. We estimate that slicks can reduce CO2

  19. C60 superstructure and carbide formation on the Al-terminated Al9Co2(001 ) surface

    Science.gov (United States)

    Ledieu, J.; Gaudry, É.; de Weerd, M.-C.; Gille, P.; Diehl, R. D.; Fournée, V.

    2015-04-01

    We report the formation of an ordered C60 monolayer on the Al9Co2 (001) surface using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and ab initio calculations. Dosing fullerenes at 300 K results in a disordered overlayer. However, the adsorption of C60 with the sample held between 573-673 K leads to a [4, -2 ∣1 ,3 ] phase. The growth of C60 proceeds with the formation of two domains which are mirror symmetric with respect to the [100] direction. Within each domain, the superstructure unit cell contains six molecules and this implies an area per fullerene equal to 91 Å2. The molecules exhibit two types of contrast (bright and dim) which are bias dependent. The adsorption energies and preferred molecular configuration at several possible adsorption sites have been determined theoretically. These calculations lead to a possible scheme describing the configuration of each C60 in the observed superstructure. Several defects (vacancies, protrusions,…) and domain boundaries observed in the film are also discussed. If the sample temperature is higher than 693 K when dosing, impinging C60 molecules dissociate at the surface, hence leading to the formation of a carbide film as observed by STM and LEED measurements. The formation of Al4C3 domains and the molecular dissociation are confirmed by XPS/UPS measurements acquired at different stages of the experiment. The cluster substructure present at the Al9Co2 (001) surface dictates the carbide domain orientations.

  20. Using the Surface Renewal Technique to Estimate CO2 Exchange from a Rice Field to the Atmosphere

    Science.gov (United States)

    Suvocarev, K.; Reba, M. L.; Runkle, B.

    2015-12-01

    Measuring CO2 emissions as surface fluxes is crucial for climate change predictions. One major set of techniques to measure surface fluxes is through continuous micrometeorological observations over different landscapes. Recent approaches of the surface renewal method (SR) are becoming important for their capacity to independently measure sensible (H) and latent heat (LE) fluxes while avoiding some of the shortcomings of the eddy covariance method (EC). Unlike EC, SR avoids orientation limitations, leveling requirements and instrumentation separation and shadowing issues. The main advantage of SR over EC method is in its applicability in both roughness and inertial sub-layers. Therefore, SR measurements can be planned in cases where fetch requirements are not adequate for EC application. We applied the recent approach as suggested by Castellvi et al. (2008) over two months (May to July, 2015) of high-frequency data collected by EC equipment from a rice field in Arkansas. The main goal was to extend this SR application to CO2 fluxes (Fc) over agricultural fields. The results show high correlation between EC and SR fluxes (H, LE and Fc) when they are compared for all atmospheric stability conditions (R2 > 0.75). Some overestimation is observed for SR with respect to EC fluxes, similar to the findings of Castellvi et al. (2008) for rangeland grass. For all the data, SR analysis results were about 11%, 18% and 17% higher than the EC results for H, LE and Fc, respectively. These higher flux estimates resulted in better energy balance closure. The root mean square error for Fc was 6.55 μmol m-2 s-1. The observed overestimation will be addressed in the future by using additional methods for the turbulent fluxes quantification.

  1. Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

    Directory of Open Access Journals (Sweden)

    M. Madić

    2013-09-01

    Full Text Available This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function , while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots . The final goal of the experimental study Focuses on the determinationof the optimum laser cutting parameters for the minimization of surface roughness . Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA was selected as a method for the optimization of surface roughness.

  2. Surface and Electrochemical Behavior of HSLA in Supercritical CO2-H2O Environment

    Energy Technology Data Exchange (ETDEWEB)

    M. Ziomek-Moroz; G. R. Holcomb; J. Tylczak; J. Beck; M. Fedkin; S. Lvov

    2012-01-11

    General corrosion was observed on high strength low alloy carbon steel after electrochemical impedance spectroscopy experiments (EIS) performed in H{sub 2}O saturated with CO{sub 2} at 50 C and 15.2 MPa. However, general and localized were observed on the same material surfaces after the EIS experiments performed in supercritical CO{sub 2} containing approximately 6100 ppmv H{sub 2}O at 50 C and 15.2 MPa. The general corrosion areas were uniformly covered by the FeCO{sub 3}-like phase identified by X-ray diffraction (XRD). In the area of localized corrosion, XRD also revealed FeCO{sub 3}-rich islands embedded in {alpha}-iron. The energy dispersive X-ray (EDX) analysis revealed high concentrations of iron, carbon, and oxygen in the area affected by general corrosion and in the islands formed in the area of localized corrosion. The real and imaginary impedances were lower in H{sub 2}O saturated with CO{sub 2} than those in the supercritical CO{sub 2} containing the aqueous phase indicating faster corrosion kinetics in the former.

  3. Spatial variability in surface-water pCO2 and gas exchange in the world's largest semi-enclosed estuarine system: St. Lawrence Estuary (Canada)

    Science.gov (United States)

    Dinauer, Ashley; Mucci, Alfonso

    2017-07-01

    The incomplete spatial coverage of CO2 partial pressure (pCO2) measurements across estuary types represents a significant knowledge gap in current regional- and global-scale estimates of estuarine CO2 emissions. Given the limited research on CO2 dynamics in large estuaries and bay systems, as well as the sources of error in the calculation of pCO2 (carbonic acid dissociation constants, organic alkalinity), estimates of air-sea CO2 fluxes in estuaries are subject to large uncertainties. The Estuary and Gulf of St. Lawrence (EGSL) at the lower limit of the subarctic region in eastern Canada is the world's largest estuarine system, and is characterized by an exceptional richness in environmental diversity. It is among the world's most intensively studied estuaries, yet there are no published data on its surface-water pCO2 distribution. To fill this data gap, a comprehensive dataset was compiled from direct and indirect measurements of carbonate system parameters in the surface waters of the EGSL during the spring or summer of 2003-2016. The calculated surface-water pCO2 ranged from 435 to 765 µatm in the shallow partially mixed upper estuary, 139-578 µatm in the deep stratified lower estuary, and 207-478 µatm along the Laurentian Channel in the Gulf of St. Lawrence. Overall, at the time of sampling, the St. Lawrence Estuary served as a very weak source of CO2 to the atmosphere, with an area-averaged CO2 degassing flux of 0.98 to 2.02 mmol C m-2 d-1 (0.36 to 0.74 mol C m-2 yr-1). A preliminary analysis revealed that respiration (upper estuary), photosynthesis (lower estuary), and temperature (Gulf of St. Lawrence) controlled the spatial variability in surface-water pCO2. Whereas we used the dissociation constants of Cai and Wang (1998) to calculate estuarine pCO2, formulations recommended for best practices in open ocean environments may underestimate pCO2 at low salinities, while those of Millero (2010) may result in overestimates.

  4. Parameters optimization of supercritical fluid-CO2 extracts of frankincense using response surface methodology and its pharmacodynamics effects.

    Science.gov (United States)

    Zhou, Jing; Ma, Xing-miao; Qiu, Bi-Han; Chen, Jun-xia; Bian, Lin; Pan, Lin-mei

    2013-01-01

    The volatile oil parts of frankincense (Boswellia carterii Birdw.) were extracted with supercritical carbon dioxide under constant pressure (15, 20, or 25 MPa) and fixed temperature (40, 50, or 60°C), given time (60, 90, or 120 min) aiming at the acquisition of enriched fractions containing octyl acetate, compounds of pharmaceutical interest. A mathematical model was created by Box-Behnken design, a popular template for response surface methodology, for the extraction process. The response value was characterized by synthetical score, which comprised yields accounting for 20% and content of octyl acetate for 80%. The content of octyl acetate was determined by GC. The supercritical fluid extraction showed higher selectivity than conventional steam distillation. Supercritical fluid-CO(2) for extracting frankincense under optimum condition was of great validity, which was also successfully verified by the pharmacological experiments.

  5. Surface CO2 Exchange Dynamics across a Climatic Gradient in McKenzie Valley: Effect of Landforms, Climate and Permafrost

    Directory of Open Access Journals (Sweden)

    Natalia Startsev

    2016-11-01

    Full Text Available Northern regions are experiencing considerable climate change affecting the state of permafrost, peat accumulation rates, and the large pool of carbon (C stored in soil, thereby emphasizing the importance of monitoring surface C fluxes in different landform sites along a climate gradient. We studied surface net C exchange (NCE and ecosystem respiration (ER across different landforms (upland, peat plateau, collapse scar in mid-boreal to high subarctic ecoregions in the Mackenzie Valley of northwestern Canada for three years. NCE and ER were measured using automatic CO2 chambers (ADC, Bioscientific LTD., Herts, England, and soil respiration (SR was measured with solid state infrared CO2 sensors (Carbocaps, Vaisala, Vantaa, Finland using the concentration gradient technique. Both NCE and ER were primarily controlled by soil temperature in the upper horizons. In upland forest locations, ER varied from 583 to 214 g C·m−2·year−1 from mid-boreal to high subarctic zones, respectively. For the bog and peat plateau areas, ER was less than half that at the upland locations. Of SR, nearly 75% was generated in the upper 5 cm layer composed of live bryophytes and actively decomposing fibric material. Our results suggest that for the upland and bog locations, ER significantly exceeded NCE. Bryophyte NCE was greatest in continuously waterlogged collapsed areas and was negligible in other locations. Overall, upland forest sites were sources of CO2 (from 64 g·C·m−2·year−1 in the high subarctic to 588 g C·m−2·year−1 in mid-boreal zone; collapsed areas were sinks of C, especially in high subarctic (from 27 g·C·m−2 year−1 in mid-boreal to 86 g·C·m−2·year−1 in high subarctic and peat plateaus were minor sources (from 153 g·C·m−2·year−1 in mid-boreal to 6 g·C·m−2·year−1 in high subarctic. The results are important in understanding how different landforms are responding to climate change and would be useful in modeling the

  6. The relative influence of H2O and CO2 on the primitive surface conditions and evolution of rocky planets

    Science.gov (United States)

    Salvador, A.; Massol, H.; Davaille, A.; Marcq, E.; Sarda, P.; Chassefière, E.

    2017-07-01

    How the volatile content influences the primordial surface conditions of terrestrial planets and, thus, their future geodynamic evolution is an important question to answer. We simulate the secular convective cooling of a 1-D magma ocean (MO) in interaction with its outgassed atmosphere. The heat transfer in the atmosphere is computed either using the grey approximation or using a k-correlated method. We vary the initial CO2 and H2O contents (respectively from 0.1 × 10-2 to 14 × 10-2 wt % and from 0.03 to 1.4 times the Earth Ocean current mass) and the solar distance—from 0.63 to 1.30 AU. A first rapid cooling stage, where efficient MO cooling and degassing take place, producing the atmosphere, is followed by a second quasi steady state where the heat flux balance is dominated by the solar flux. The end of the rapid cooling stage (ERCS) is reached when the mantle heat flux becomes negligible compared to the absorbed solar flux. The resulting surface conditions at ERCS, including water ocean's formation, strongly depend both on the initial volatile content and solar distance D. For D > DC, the "critical distance," the volatile content controls water condensation and a new scaling law is derived for the water condensation limit. Although today's Venus is located beyond DC due to its high albedo, its high CO2/H2O ratio prevents any water ocean formation. Depending on the formation time of its cloud cover and resulting albedo, only 0.3 Earth ocean mass might be sufficient to form a water ocean on early Venus.

  7. Determination of extraction conditions of Ginkgo biloba L. leaves by supercritical CO2 using response surface methodology

    Directory of Open Access Journals (Sweden)

    Milošević Svetlana G.

    2011-01-01

    Full Text Available The effects of process parameters on the extraction of Ginkgo biloba L. leaves with supercritical carbon dioxide were investigated. The investigated parameters include particle size (mean particle diameter 0.19, 0.467 and 1.009 mm, solvent flow rate (1.5810-3, 3.2210-3 and 4.1610-3 kg CO2/min and pressure (100-300 bar, which were obtained by the response surface methodology (RSM under the following condition ranges: temperature 40-50-60ºC, pressure 100-140-180 bar and extraction time of 2-3-4 h at the flow rate of 3.2210-3 kg/min. Based on the experimental results of kinetics of Ginkgo biloba leaves extraction with supercritical carbon dioxide, modeling of the extraction system of Ginkgo biloba-supercritical CO2 was done. Two mathematical models (Reverchon-Sesti Osseo and Sovová were applied to correlate the experimental data. RSM was applied to optimize the process parameters of supercritical carbon dioxide extraction of Ginkgo biloba L. leaves. A second-order polynomial response surface equation was developed indicating the effect of variables on Ginkgo biloba extraction yield. The statistical analysis of the experiment indicated that pressure (X1, extraction time (X3, the quadratic of temperature (X22, and the interaction between pressure and extraction time (X1X3, show significant effect on the extraction yield. The results showed that the data were adequately fitted into the second-order polynomial model. It was predicted that the optimum extraction process parameters within the experimental ranges would be the extraction temperature of 52.7ºC, the pressure of 184.4 bar, and the extraction time of 3.86 h. Under these conditions, the predicted extraction yield is 2.39% (g/100 g drug.

  8. The bending machine: CO2 activation and hydrogenation on δ-MoC(001) and β-Mo2C(001) surfaces.

    Science.gov (United States)

    Posada-Pérez, Sergio; Viñes, Francesc; Ramirez, Pedro J; Vidal, Alba B; Rodriguez, José A; Illas, Francesc

    2014-07-28

    The adsorption and activation of a CO2 molecule on cubic δ-MoC(001) and orthorhombic β-Mo2C(001) surfaces have been investigated by means of periodic density functional theory based calculations using the Perdew-Burke-Ernzerhof exchange-correlation functional and explicitly accounting for (or neglecting) the dispersive force term description as proposed by Grimme. The DFT results indicate that an orthorhombic β-Mo2C(001) Mo-terminated polar surface provokes the spontaneous cleavage of a C-O bond in CO2 and carbon monoxide formation, whereas on a β-Mo2C(001) C-terminated polar surface or on a δ-MoC(001) nonpolar surface the CO2 molecule is activated yet the C-O bond prevails. Experimental tests showed that Mo-terminated β-Mo2C(001) easily adsorbs and decomposes the CO2 molecule. This surface is an active catalyst for the hydrogenation of CO2 to methanol and methane. Although MoC does not dissociate C-O bonds on its own, it binds CO2 better than transition metal surfaces and is an active and selective catalyst for the CO2 + 3H2 → CH3OH + H2O reaction. Our theoretical and experimental results illustrate the tremendous impact that the carbon/metal ratio has on the chemical and catalytic properties of molybdenum carbides. This ratio must be taken into consideration when designing catalysts for the activation and conversion of CO2.

  9. Reconstruction of surface ocean water pCO2(aq) in Nansha area, the South China Sea during the last 30 ka

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The reconstruction of pCO2 in the tropic ocean is one of the most important issues to understand global climatic changes. In this study, the high-resolution stratigraphic analysis of core 17962 was conducted, which is located in the southern South China Sea (SCS). The contents of sedimentary organic matter, the stable carbon isotopic composition of sedimentary organic matter, and the δ13C values of black carbon and terrigenous n-alkanes were determined. And the δ13Cwc value of carbon derived from aquatic was calculated. On the basis of δ13Corg-pCO2 equation proposed by Popp et al. (1989), we estimated the pCO2 in the Nansha area, SCS, since the last glaciation using δ13Cwc instead of δ13Corg. The results show that the average pCO2 was estimated at 240 ppmV during the last glaciation, and at 320 ppmV in the Holocene. A comparison of surface sea pCO2 with the atmosphere CO2 recorded in the Vostok ice core, indicates that CO2 in surface water of the southern SCS could emit into atmosphere during the last 30 ka.

  10. Recycling of CO2: Probing the Chemical State of the Ni(111) Surface during the Methanation Reaction with Ambient-Pressure X-Ray Photoelectron Spectroscopy.

    Science.gov (United States)

    Heine, Christian; Lechner, Barbara A J; Bluhm, Hendrik; Salmeron, Miquel

    2016-10-12

    Using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), we studied the adsorption and reactions of CO2 and CO2 + H2 on the Ni(111) surface to identify the surface chemical state and the nature of the adsorbed species during the methanation reaction. In 200 mTorr CO2, we found that NiO is formed from CO2 dissociation into CO and atomic oxygen. Additionally, carbonate (CO3(2-)) is present on the surface from further reaction of CO2 with NiO. The addition of H2 into the reaction environment leads to reduction of NiO and the disappearance of CO3(2-). At temperatures >160 °C, CO adsorbed on hollow sites, and atomic carbon and OH species are present on the surface. We conclude that the methanation reaction proceeds via dissociation of CO2, followed by reduction of CO to atomic carbon and its hydrogenation to methane.

  11. Surface plasma preionization produced on a specially patterned PCB and its application in a pulsed CO2 laser

    Science.gov (United States)

    Ghorbanzadeh, Atamalek; Pakmanesh, Nahid; Rastegari, Ali; Abdolghader, Pedram; Feizollah, Peyman; Siadati, Neda

    2016-04-01

    The performance of an atmospheric pressure pulsed carbon dioxide laser employing surface plasma preionization, produced on a specially patterned printed circuit board (PCB), is reported. The surface plasma is formed due to many tiny plasma channels produced in millimeter sized open circular gaps, made by lithography on one side of PCB. The preionizing plasma is mostly consisted of corona or glow stage and transition to spark one hardly occurs. This type of preionization allows a maximum of 220 J/l energy deposition into the main plasma, while up scaling is yet possible by more optimization of PCB and the pattern. The laser output energy of 1.2 J per pulse with overall efficiency of 7% has been obtained with gas mixture of He:CO2:N2=3:1:1. This type of surface plasma preionization is specifically appropriate for very large volumes and high pressures, where the conventional UV emitting preionizations like spark arrays or corona are not effective.

  12. The 13C Suess effect in scleractinian corals mirror changes in the anthropogenic CO2 inventory of the surface oceans

    Science.gov (United States)

    Swart, Peter K.; Greer, Lisa; Rosenheim, Brad E.; Moses, Chris S.; Waite, Amanda J.; Winter, A.; Dodge, Richard E.; Helmle, Kevin

    2010-03-01

    New δ13C data are presented from 10 coral skeletons collected from Florida and elsewhere in the Caribbean (Dominica, Dominican Republic, Puerto Rico, and Belize). These corals range from 96 to 200 years in age and were collected between 1976 and 2002. The change in the δ13C of the skeletons from these corals between 1900 and 1990 has been compared with 27 other published coral records from the Atlantic, Pacific, and Indian Oceans. The new data presented here make possible, for the first time, a global comparison of rates of change in the δ13C value of coral skeletons. Of these records, 64% show a statistically significant (p open oceanic conditions is approximately -0.01‰ yr-1. In the Atlantic Ocean the magnitude of the decrease since 1960,-0.019 yr-1 ±0.015‰, is essentially the same as the decrease in the δ13C of atmospheric CO2 and the δ13C of the oceanic dissolved inorganic carbon (-0.023 to -0.029‰ yr-1), while in the Pacific and Indian Oceans the rate is more variable and significantly reduced (-0.007‰ yr-1 ±0.013). These data strongly support the notion that (i) the δ13C of the atmosphere controls ambient δ13C of the dissolved inorganic carbon which in turn is reflected in the coral skeletons, (ii) the rate of decline in the coral skeletons is higher in oceans with a greater anthropogenic CO2 inventory in the surface oceans, (iii) the rate of δ13C decline is accelerating. Superimposed on these secular variations are controls on the δ13C in the skeleton governed by growth rate, insolation, and local water masses.

  13. The effect of nitrogen doping on mercury oxidation/chemical adsorption on the CuCo2O4(110) surface: a molecular-level description.

    Science.gov (United States)

    Mei, Zhijian; Fan, Maohong; Zhang, Ruiqing; Shen, Zhemin; Wang, Wenhua

    2014-07-14

    Based on density functional theory (DFT) calculations, the detailed mercury oxidation/chemical adsorption mechanisms on the N-doped CuCo2O4(110) surface are studied. The DFT calculations show that Ow (bonded with one Cu(2+) ion and one Co(3+) ion) is far more active than Os (bonded with three Co(3+) ions) and the mercury oxidation/chemical adsorption activation energy (Ea) on the virgin CuCo2O4(110) surface involving Ow is 0.85 eV. The physically adsorbed mercury overcomes the Ea and enters the energy well that plays an important role in mercury oxidation/chemical adsorption. Nitrogen doping can greatly increase the activity of Ow and decrease the activity of Os at the same time, which greatly affect the mercury oxidation/chemical adsorption abilities on the CuCo2O4(110) surface, and the Ea variation of mercury oxidation/chemical adsorption is as follows: 0.85 eV (virgin CuCo2O4(110)) → 0.76 eV (one N-doped CuCo2O4(110)) → 0.69 eV (two N-doped CuCo2O4(110)) → 0.48 eV (three N-doped CuCo2O4(110)). In addition, N-doping can decrease the adsorption energy of mercury and mercuric oxide. The effect of N-doping on the bonding mechanism of mercury adsorption on the CuCo2O4(110) surface is analyzed by the local density of state (LDOS) and the natural bonding orbital (NBO). The calculation results correspond well to the experimental data.

  14. Surface-Plasmon-Enhanced Photodriven CO2 Reduction Catalyzed by Metal-Organic-Framework-Derived Iron Nanoparticles Encapsulated by Ultrathin Carbon Layers.

    Science.gov (United States)

    Zhang, Huabin; Wang, Tao; Wang, Junjie; Liu, Huimin; Dao, Thang Duy; Li, Mu; Liu, Guigao; Meng, Xianguang; Chang, Kun; Shi, Li; Nagao, Tadaaki; Ye, Jinhua

    2016-05-01

    Highly efficient utilization of solar light with an excellent reduction capacity is achieved for plasmonic Fe@C nanostructures. By carbon layer coating, the optimized catalyst exhibits enhanced selectivity and stability applied to the solar-driven reduction of CO2 into CO. The surface-plasmon effect of iron particles is proposed to excite CO2 molecules, and thereby facilitates the final reaction activity.

  15. Spatial and Temporal Variability of CO2 and CH4 Concentrations in the Atmospheric Surface Layer over West Siberia

    Science.gov (United States)

    Belan, Boris D.; Machida, Toshinobu; Sasakawa, Motoki; Davydov, Denis K.; Fofonov, Alexander V.; Krasnov, Oleg A.; Maksyutov, Shamil; Arshinov, Mikhail Yu.

    2015-04-01

    The investigation of greenhouse gas behavior in the atmosphere plays a key role in predicting the global changes of Earth's climate. In this connection, of particular importance is the study of the distribution of sources/sinks of trace gases in the atmospheric surface layer over the different regions of the globe. In order to fill a gap in the data on greenhouse gas concentrations in Russia, National Institute for Environmental Studies (NIES, Japan) and Institute of Atmospheric Optics (IAO SB RAS, Russia) established a network for GHG monitoring (JR-STATION, Japan-Russia Siberian Tall Tower Inland Observation Network). Gas analyzers and meteorological sensors were mounted at radio relay towers located in different regions of West Siberia. The checking equipment was placed in containers at the tower base. In the containers, the climatic parameters optimal for gas analyzer operation were maintained. The work on the network development started in 2001. Since at each of the sites the measurement duration could be different, in this paper we present the data of the greenhouse gas monitoring for eight sites which give the primary idea on the spatial distribution and temporal dynamics of CO2 and CH4 in the atmospheric surface layer over West Siberia. The analysis of the data showed that the average increase in concentration of carbon dioxide by results of our measurements in this territory increases within 1.95 - 2.53 ppm/year, depending on the area. The analysis of long-term data testifies about existence of growth of concentration of methane within 3.2 - 7.2 ppb / year. The presence of a distributed network of the sites operating in the monitoring regime makes it possible not only to investigate the temporal dynamics of CO2 and CH4 at each site and to determine the spatial differences between the concentrations by comparing the data, but also to plot the distribution charts for different moments of time. This work was supported by the Global Environment Research

  16. High speed CO2 laser surface modification of iron/cobalt co-doped boroaluminosilicate glass and the impact on surface roughness, gloss and wettability

    Science.gov (United States)

    Hodgson, S. D.; Waugh, D. G.; Gillett, A.; Lawrence, J.

    2016-07-01

    A preliminary study into the impact of high speed laser processing on the surface of iron and cobalt co-doped glass substrates using a 60 W continuous wave (cw) CO2 laser. Two types of processing, termed fill-processing and line-processing, were trialled. In fill-processed samples the surface roughness of the glass was found to increase linearly with laser power from an S a value of 20.8 nm-2.1 μm at a processing power of 54 W. With line processing, a more exponential-like increase was observed with a roughness of 4 μm at 54 W. The change in surface properties of the glass, such as gloss and wettability, have also been measured. The contact angle of water was found to increase after laser processing by up to 64°. The surface gloss was varied between 45 and 100 gloss units (GUs).

  17. Distribution of CO2 ice on the large moons of Uranus and evidence for compositional stratification of their near-surfaces

    CERN Document Server

    Cartwright, Richard J; Rivkin, Andy S; Trilling, David E; Pinilla-Alonso, Noemi

    2015-01-01

    The surfaces of the large Uranian satellites are characterized by a mixture of H2O ice and a dark, potentially carbon-rich, constituent, along with CO2 ice. At the mean heliocentric distance of the Uranian system, native CO2 ice should be removed on timescales shorter than the age of the Solar System. Consequently, the detected CO2 ice might be actively produced. Analogous to irradiation of icy moons in the Jupiter and Saturn systems, we hypothesize that charged particles caught in Uranus' magnetic field bombard the surfaces of the Uranian satellites, driving a radiolytic CO2 production cycle. To test this hypothesis, we investigated the distribution of CO2 ice by analyzing near-infrared (NIR) spectra of these moons, gathered using the SpeX spectrograph at NASA's Infrared Telescope Facility (IRTF) (2000 - 2013). Additionally, we made spectrophotometric measurements using images gathered by the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope (2003 - 2005). We find that the detected CO2 ice is ...

  18. Fabrication of Polyimide Membrane Incorporated with Functional Graphene Oxide for CO2 Separation: The Effects of GO Surface Modification on Membrane Performance.

    Science.gov (United States)

    Wang, Ting; Cheng, Cheng; Wu, Li-Guang; Shen, Jiang-Nan; Van der Bruggen, Bart; Chen, Qian; Chen, Di; Dong, Chun-Ying

    2017-06-06

    Two kinds of isocyanate were used to modify graphene oxide (GO) samples. Then, polyimide (PI) hybrid membranes containing GO and modified GO were prepared by in situ polymerization. The permeation of CO2 and N2 was studied using these novel membranes. The morphology experiments showed that the isocyanate groups were successfully grafted on the surface of GO by replacement of the oxygen-containing functional groups. After modification, the surface polarity of the GO increased, and more defect structures were introduced into the GO surface. This resulted in a good distribution of more modified GO samples in the PI polymer matrix. Thus, the PI hybrid membranes incorporated by modified GO samples showed a high gas permeability and ideal selectivity of membranes. In addition, enhancement of the selectivity due to the solubility of CO2 played a major role in the increase in the separation performance of the hybrid membranes for CO2, although the diffusion coefficients for CO2 also increased. Both the higher condensability and the strong affinity between CO2 molecules and GO in the polymer matrix caused an enhancement of the solubility selectivity higher than the diffusion selectivity after GO surface modification.

  19. Regional assimilation of CO2 and δ13C surface data to assess terrestrial biosphere models under drought stress

    Science.gov (United States)

    van der Velde, I. R.; Miller, J. B.; Alden, C. B.; Andrews, A. E.; Schaefer, K. M.; Peters, W.; Tans, P. P.; Vaughn, B. H.; White, J. W. C.

    2016-12-01

    Observed atmospheric carbon dioxide (CO2) and the ratios of its stable isotopologue 13CO2/12CO2 (δ13C) contain unique signals of large-scale drought stress that affect the biosphere. When plants experience physiological stress due to heat and drought at leaf level they respond by closing their stomata. This is a safety mechanism that prevents excessive water loss at the expense of carbon uptake, and it changes the overall water-use efficiency. During photosynthesis, 12CO2 is preferentially assimilated over 13CO2, leaving the atmosphere enriched in 13CO2. Water stress slightly changes the ratio of 13CO2 and 12CO2 molecules being removed from the atmosphere, i.e., a reduction of canopy isotope discrimination (Δ), and its changes are evident in atmospheric δ13C.To improve our understanding of the coupled vegetation-atmosphere system we are developing an ensemble Kalman filter assimilation of high precision measurements of CO2 and δ13C from air samples collected over North America. It uses footprints provided by WRF-STILT that allows for efficient atmospheric transport simulations on a much higher horizontal resolution than with a global Eulerian transport model. To force consistency with atmospheric CO2 and δ13C observations we will optimize regional net terrestrial CO2 exchange (NEE) and Δ from a terrestrial biosphere model. We will carefully evaluate the sensitivity of the optimized parameters to uncertainties in the terrestrial biosphere fluxes, observations, time/space aggregation methods, and boundary conditions. Our main questions are: (i) what signal-to-noise in the data, as interpreted by the model, is large enough to robustly estimate Δ and NEE? and (ii) how do the optimized NEE and Δ that are based on the atmospheric constraint compare with the predicted NEE and Δ that are based on biophysical parameterizations? Our ability to accurately predict the responses of the terrestrial biosphere to changing humidity and soil moisture regimes is currently

  20. Coccolithophore surface distributions in the North Atlantic and their modulation of the air-sea flux of CO2 from 10 years of satellite Earth observation data

    Directory of Open Access Journals (Sweden)

    J. D. Shutler

    2013-04-01

    Full Text Available Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO3. These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50% and their calcification can affect the atmosphere-to-ocean (air-sea uptake of carbon dioxide (CO2 through increasing the seawater partial pressure of CO2 (pCO2. Here we document variations in the areal extent of surface blooms of the globally important coccolithophore, Emiliania huxleyi, in the North Atlantic over a 10-year period (1998–2007, using Earth observation data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS. We calculate the annual mean sea surface areal coverage of E. huxleyi in the North Atlantic to be 474 000 ± 104 000 km2, which results in a net CaCO3 carbon (CaCO3-C production of 0.14–1.71 Tg CaCO3-C per year. However, this surface coverage (and, thus, net production can fluctuate inter-annually by −54/+8% about the mean value and is strongly correlated with the El Niño/Southern Oscillation (ENSO climate oscillation index (r=0.75, pE. huxleyi blooms in the North Atlantic can increase the pCO2 and, thus, decrease the localised air-sea flux of atmospheric CO2. In regions where the blooms are prevalent, the average reduction in the monthly air-sea CO2 flux can reach 55%. The maximum reduction of the monthly air-sea CO2 flux in the time series is 155%. This work suggests that the high variability, frequency and distribution of these calcifying plankton and their impact on pCO2 should be considered if we are to fully understand the variability of the North Atlantic air-to-sea flux of CO2. We estimate that these blooms can reduce the annual N. Atlantic net sink atmospheric CO2 by between 3–28%.

  1. Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

    Directory of Open Access Journals (Sweden)

    Y. Matsumi

    2010-04-01

    Full Text Available Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA with a resolution enough to resolve rotational lines of CO2 and CH4 in the region of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI to the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

  2. Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

    Directory of Open Access Journals (Sweden)

    I. Morino

    2010-08-01

    Full Text Available Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA with a resolution enough to resolve rotational lines of CO2 and CH4 in the regions of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI to obtain the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

  3. Effects of the surface alb edo on short-wave infrared detection of atmospheric CO2%地表反照率对短波红外探测大气CO2的影响∗

    Institute of Scientific and Technical Information of China (English)

    陈洁; 张淳民; 王鼎益; 张兴赢; 王舒鹏; 栗彦芬; 刘冬冬; 荣飘

    2015-01-01

    remote sensing detectio. All these are significantly contributed to the hyperspectral satellite observation of the greenhouse gas, the investigation of global CO2 distributions, and the prediction and monitoring of the climate change.

  4. Modification of surface layers of copper under the action of the volumetric discharge initiated by an avalanche electron beam in nitrogen and CO2 at atmospheric pressure

    Science.gov (United States)

    Shulepov, M. A.; Akhmadeev, Yu. Kh.; Tarasenko, V. F.; Kolubaeva, Yu. A.; Krysina, O. V.; Kostyrya, I. D.

    2011-05-01

    The results of experimental investigations of the action of the volumetric discharge initiated by an avalanche electron beam on the surface of copper specimens are presented. The volumetric (diffuse) discharge in nitrogen and CO2 at atmospheric pressure was initiated by applying high voltage pulses of nanosecond duration to a tubular foil cathode. It has been found that the treatment of a copper surface by this type of discharge increases the hardness of the surface layer due to oxidation.

  5. Characterization of surface antigen protein 1 (SurA1) from Acinetobacter baumannii and its role in virulence and fitness.

    Science.gov (United States)

    Liu, Dong; Liu, Zeng-Shan; Hu, Pan; Cai, Ling; Fu, Bao-Quan; Li, Yan-Song; Lu, Shi-Ying; Liu, Nan-Nan; Ma, Xiao-Long; Chi, Dan; Chang, Jiang; Shui, Yi-Ming; Li, Zhao-Hui; Ahmad, Waqas; Zhou, Yu; Ren, Hong-Lin

    2016-04-15

    Acinetobacter baumannii is a Gram-negative bacillus that causes nosocomial infections, such as bacteremia, pneumonia, and meningitis and urinary tract and wound infections. In the present study, the surface antigen protein 1 (SurA1) gene of A. baumannii strain CCGGD201101 was identified, cloned and expressed, and then its roles in fitness and virulence were investigated. Virulence was observed in the human lung cancer cell lines A549 and HEp-2 at one week after treatment with recombinant SurA1. One isogenic SurA1 knock-out strain, GR0015, which was derived from the A. baumannii strain CCGGD201101 isolated from diseased chicks in a previous study, highlighted the effect of SurA1 on fitness and growth. Its growth rate in LB broth and killing activity in human sera were significantly decreased compared with strain CCGGD201101. In the Galleria mellonella insect model, the isogenic SurA1 knock-out strain exhibited a lower survival rate and decreased dissemination. These results suggest that SurA1 plays an important role in the fitness and virulence of A. baumannii.

  6. The concurrent use of novel soil surface microclimate measurements to evaluate CO2 pulses in biocrusted interspaces in a cool desert ecosystem

    Science.gov (United States)

    Tucker, Colin; McHugh, Theresa A.; Howell, Armin; Gill, Richard; Weber, Bettina; Belnap, Jayne; Grote, Ed; Reed, Sasha C.

    2017-01-01

    Carbon cycling associated with biological soil crusts, which occupy interspaces between vascular plants in drylands globally, may be an important part of the coupled climate-carbon cycle of the Earth system. A major challenge to understanding CO2 fluxes in these systems is that much of the biotic and biogeochemical activity occurs in the upper few mm of the soil surface layer (i.e., the ‘mantle of fertility’), which exhibits highly dynamic and difficult to measure temperature and moisture fluctuations. Here, we report a multi-sensor approach to simultaneously measuring temperature and moisture of this biocrust surface layer (0–2 mm), and the deeper soil profile, concurrent with automated measurement of surface soil CO2effluxes. Our results illuminate robust relationships between biocrust water content and field CO2 pulses that have previously been difficult to detect and explain. All observed CO2 pulses over the measurement period corresponded to surface wetting events, including when the wetting events did not penetrate into the soil below the biocrust layer (0–2 mm). The variability of temperature and moisture of the biocrust surface layer was much greater than even in the 0–5 cm layer of the soil beneath the biocrust, or deeper in the soil profile. We therefore suggest that coupling surface measurements of biocrust moisture and temperature to automated CO2flux measurements may greatly improve our understanding of the climatic sensitivity of carbon cycling in biocrusted interspaces in our study region, and that this method may be globally relevant and applicable.

  7. From ionic-liquid@metal-organic framework composites to heteroatom-decorated large-surface area carbons: superior CO2 and H2 uptake.

    Science.gov (United States)

    Aijaz, Arshad; Akita, Tomoki; Yang, Hui; Xu, Qiang

    2014-06-21

    For the first time, high surface area uniformly nitrogen (N)- and boron-nitrogen (BN)-decorated nanoporous carbons have been successfully fabricated by impregnation of ionic liquids (ILs) within a metal-organic framework (MOF), MIL-100(Al), followed by carbonization, which exhibit remarkable CO2 and H2 adsorption capacities.

  8. Forecasting global atmospheric CO2

    Directory of Open Access Journals (Sweden)

    A. Agustí-Panareda

    2014-05-01

    Full Text Available A new global atmospheric carbon dioxide (CO2 real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate – Interim Implementation (MACC-II service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF Integrated Forecasting System (IFS. One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 satellite retrievals, as they

  9. Characteristics of pCO2 in surface water of the Bering Abyssal Plain and their effects on carbon cycle in the western Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    CHEN Liqi; GAO Zhongyong; WANG Weiqiang; YANG Xulin

    2004-01-01

    Characteristics of the pCO2 distribution in surface water of the Bering Abyssal Plain and their relationships with the ambient hydrological conditions were discussed using variations of the partial pressure of CO2 in surface water of the Bering Abyssal Plain and the Chukchi Sea. Data in this study are from a field investigation during the First Chinese National Arctic Research Expedition in 1999. Compared to the high productivity in the Bering Continental Shelf, much lower levels of chlorophyll a were observed in the Bering Abyssal Plain. The effect of hydrological factors on the pCO2 distribution in surface seawater of the Plain in summer has become a major driving force and dominated over biological factors. The Plain also presents a High Nutrient Low Chlorophyll (HNLC). In addition, the pCO2 distribution in the Bering Abyssal Plain has also been found to be influenced from the Bering Slope Current which would transform to the Anadyr Current when it inflows northwestward over the Plain. The Anadyr Current would bring a high nutrient water to the western Arctic Ocean where local nutrients are almost depleted in the surface water during the summer time. Resupplying nutrients would stimulate the growth of phytoplankton and enhance capacity of absorbing atmospheric CO2 in the surface water. Otherwise, in the Bering Sea the dissolved inorganic carbon brought from freshwater are not deposited down to the deep sea water but most of them would be transported into the western Arctic Ocean by the Alaska Coastal Current to form a carbon sink there. Therefore, the two carbon sinks in the western Arctic Ocean, one carried by the Anadyr Current and another by the Alaska Costal Current, will implicate the western Arctic Ocean in global change.

  10. Why must a solar forcing be larger than a CO2 forcing to cause the same global mean surface temperature change?

    Science.gov (United States)

    Modak, Angshuman; Bala, Govindasamy; Cao, Long; Caldeira, Ken

    2016-04-01

    Many previous studies have shown that a solar forcing must be greater than a CO2 forcing to cause the same global mean surface temperature change but a process-based mechanistic explanation is lacking in the literature. In this study, we investigate the physical mechanisms responsible for the lower efficacy of solar forcing compared to an equivalent CO2 forcing. Radiative forcing is estimated using the Gregory method that regresses top-of-atmosphere (TOA) radiative flux against the change in global mean surface temperature. For a 2.25% increase in solar irradiance that produces the same long term global mean warming as a doubling of CO2 concentration, we estimate that the efficacy of solar forcing is ∼80% relative to CO2 forcing in the NCAR CAM5 climate model. We find that the fast tropospheric cloud adjustments especially over land and stratospheric warming in the first four months cause the slope of the regression between the TOA net radiative fluxes and surface temperature to be steeper in the solar forcing case. This steeper slope indicates a stronger net negative feedback and hence correspondingly a larger solar forcing than CO2 forcing for the same equilibrium surface warming. Evidence is provided that rapid land surface warming in the first four months sets up a land-sea contrast that markedly affects radiative forcing and the climate feedback parameter over this period. We also confirm the robustness of our results using simulations from the Hadley Centre climate model. Our study has important implications for estimating the magnitude of climate change caused by volcanic eruptions, solar geoengineering and past climate changes caused by change in solar irradiance such as Maunder minimum.

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

    Science.gov (United States)

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

    2015-06-25

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

  12. Rapid increase of observed DIC and pCO(2) in the surface waters of the North Sea in the 2001-2011 decade ascribed to climate change superimposed by biological processes

    NARCIS (Netherlands)

    Clargo, Nicola M.; Salt, Lesley A.; Thomas, Helmuth; de Baar, Hein J.W.

    2015-01-01

    The CO2 system in the North Sea over the 2001-2011 decade was investigated using four comprehensive basin-wide datasets covering the late summer periods of 2001, 2005, 2008 and 2011. We find that rises in surface water DIC and pCO(2) exceeded concurrent rises in atmospheric pCO(2), which we attribut

  13. Rapid increase of observed DIC and pCO(2) in the surface waters of the North Sea in the 2001-2011 decade ascribed to climate change superimposed by biological processes

    NARCIS (Netherlands)

    Clargo, Nicola M.; Salt, Lesley A.; Thomas, Helmuth; de Baar, Hein J.W.

    2015-01-01

    The CO2 system in the North Sea over the 2001-2011 decade was investigated using four comprehensive basin-wide datasets covering the late summer periods of 2001, 2005, 2008 and 2011. We find that rises in surface water DIC and pCO(2) exceeded concurrent rises in atmospheric pCO(2), which we

  14. Designed polar cosolvent-modified supercritical CO2 removing caffeine from and retaining catechins in green tea powder using response surface methodology.

    Science.gov (United States)

    Huang, Kuo-Jong; Wu, Jia-Jiuan; Chiu, Yung-Ho; Lai, Cheng-Yung; Chang, Chieh-Ming J

    2007-10-31

    This study examines cosolvent-modified supercritical carbon dioxide (SC-CO2) to remove caffeine from and to retain catechins in green tea powder. The response surface method was adopted to determine the optimal operation conditions in terms of the extraction efficiencies and concentration factors of caffeine and catechins during the extractions. When SC-CO2 was used at 333 K and 300 bar, 91.5% of the caffeine was removed and 80.8% of catechins were retained in the tea: 3600 g of carbon dioxide was used in the extraction of 4 g of tea soaked with 1 g of water. Under the same extraction conditions, 10 g of water was added to decaffeination increased the concentrations of caffeine in the SC-CO2 extracts at 353 K.

  15. 用于清除水面污染物的移动式气动CO2激光器%Jet engine based mobile gas dynamic CO2 laser for water surface cleaning

    Institute of Scientific and Technical Information of China (English)

    APOLLONOV V V

    2012-01-01

    本文介绍的工程项目在于研发一种激光技术来清除大面积海域和其他水面存在的油膜污染物.针对海面严重污染问题,研究了基于喷气发动机的可移动气动CO2激光器(100~250 kW)的设计方案及其在清除水面污染时的工程实现.提出的技术方案意在有效弥补传统的海面油膜处理方法只可处理块状油层而无法消除100 μm厚油膜的弊病.文中介绍了可移动气动CO2激光器的设计机理,研究了可执行该项工作的不同类型的激光器,证明了选用可移动气动CO2激光器执行该项工作的合理性.考虑了激光器系统的供气方案,选择了高质量的喷气发动机作气动CO2激光器的动力设备并设置了该设备工作时需要的容量.最后,描述了该激光系统气动液压设备的设计方案,给出了相关设备、油箱、和操作控制单元的结构.目前,作者已经完成了用于处理水面油膜的气动CO2激光器的概念设计,并制备了相应的激光系统.另外,研制了气动CO2激光器系统的工作平台,通过用激光束扫描石油膜覆盖的水面,实验验证了利用该系统收集油膜和令油膜有效燃烧的可行性.%The purpose of the project presented in the paper is to develop a laser technology to clean large areas of seas and other water surfaces from oil film contamination.It mainly aims development of technological scheme and engineering design of jet engine based mobile Gas Dynamic Lasers (GDLs) (100-250 kW) intended to solve this important problem of environment protection.This method and laser system proposed are expected to complement other traditional methods,which usually more successfully treat bulk layer oil pollution but do not match to eliminate up to 100 μm oil films.In this paper,the basic design concept of a mobile gas dynamic CO2 laser is introduced,and the possibility of using various types of lasers for solution of required tasks is considered and the selection of GDL

  16. Ikaite crystals in melting sea ice - implications for pCO(2) and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, Ronnie N.; Lennert, K.

    2012-01-01

    that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km(2) (0.5-1m thick) drifting ice floe......, melt reduced the ice floe thickness by 0.2m per week and resulted in an estimated 3.8 ppm decrease of pCO(2) in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m(-2) sea ice d(-1) or to 3.3 ton km(-2) ice floe week(-1). This is markedly higher than the estimated...... primary production within the ice floe of 0.3-1.3 mmol m(-2) sea ice d(-1). Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO(2) uptake...

  17. WRFv3.2-SPAv2: development and validation of a coupled ecosystem–atmosphere model, scaling from surface fluxes of CO2 and energy to atmospheric profiles

    Directory of Open Access Journals (Sweden)

    T. L. Smallman

    2013-07-01

    Full Text Available The Weather Research and Forecasting meteorological (WRF model has been coupled to the Soil–Plant–Atmosphere (SPA terrestrial ecosystem model, to produce WRF-SPA. SPA generates realistic land–atmosphere exchanges through fully coupled hydrological, carbon and energy cycles. The addition of a~land surface model (SPA capable of modelling biospheric CO2 exchange allows WRF-SPA to be used for investigating the feedbacks between biosphere carbon balance, meteorology, and land use and land cover change. We have extensively validated WRF-SPA using multi-annual observations of air temperature, turbulent fluxes, net radiation and net ecosystem exchange of CO2 at three sites, representing the dominant vegetation types in Scotland (forest, managed grassland and arable agriculture. For example air temperature is well simulated across all sites (forest R2 = 0.92, RMSE = 1.7 °C, bias = 0.88 °C; managed grassland R2 = 0.73, RMSE = 2.7 °C, bias = −0.30 °C; arable agriculture R2 = 0.82, RMSE = 2.2 °C, bias = 0.46 °C; RMSE, root mean square error. WRF-SPA generates more realistic seasonal behaviour at the site level compared to an unmodified version of WRF, such as improved simulation of seasonal transitions in latent heat flux in arable systems. WRF-SPA also generates realistic seasonal CO2 exchanges across all sites. WRF-SPA is also able to realistically model atmospheric profiles of CO2 over Scotland, spanning a 3 yr period (2004–2006, capturing both profile structure, indicating realistic transport, and magnitude (model–data residual 2 exchange. WRF-SPA makes use of CO2 tracer pools and can therefore identify and quantify land surface contributions to the modelled atmospheric CO2 signal at a specified location.

  18. Simulation analysis and verification of surface CO2 flux over Pearl River Delta, China%珠江三角洲近地层CO2通量模拟分析与评估验证

    Institute of Scientific and Technical Information of China (English)

    麦博儒; 安兴琴; 邓雪娇; 周凌晞; 王春林; 李菲; 黄建平; 陈玲; 尹淑娴

    2014-01-01

    利用能分别代表珠江三角洲草地、城市绿地及地带性森林植被生态系统的番禺站、东莞站和鼎湖山站CO2净通量资料对CT-2010碳源汇反演模式系统进行了验证,并利用该模式初步分析了区域净碳通量的时空分布及不同生态系统的碳汇特征.结果表明:CT-2010模式模拟的珠江三角洲城市绿地、地带性植被、以及草地生态系统碳通量与站点观测结果具有较好的一致性,其拟合相关系数(r)高于0.60(P<0.01),小时、逐日、日变化的残差均值低于2.0µmol/(m2·s);模式一定程度上能反映3种生态系统碳通量的季节分布特征,但各月的模拟值均高于观测值,其中对城市绿地生态系统的模拟最接近,残差年均值为0.964µmol/(m2·s),对草地和地带性森林植被生态系统的模拟效果相当,残差年均值分别为2.056,2.100µmol/(m2·s);2004~2005年期间珠江三角洲地区近地层净碳通量为3.43µmol/(m2·s),其中冬季最强,为1.4µmol/(m2·s),春季次之,为1.35µmol/(m2·s),秋季和夏季最低,分别为0.51和0.18µmol/(m2·s);在冬、春两季,珠江三角洲区域为强的碳源区,而在夏、秋季,粤北和粤东大部分地区为较弱碳汇区;2004~2005年期间珠江三角洲地区陆地生态系统的碳汇为-6.5×10-3PgC,其中农作物,草地/灌木,常绿针叶/阔叶混合林是吸收CO2的主要生态系统,其净通量占陆地生态系统的比率分别为42.01%,31.46%和26.53%.%Carbon dioxide is the primary greenhouse gas involved in climate change. This gas is responsible for 85%of the increase in radiative forcing over the past decade and 81%over the last five years. Accurate estimations of strength and spatiotemporal distributions of surface sources and sinks of CO2 are thus of great interest to the scientific community and policy makers. The CO2 measurement and modeling system developed by the National Oceanic and Atmospheric Administration and called the Carbon

  19. Variation of CO2 mole fraction in the lower free troposphere, in the boundary layer and at the surface

    Directory of Open Access Journals (Sweden)

    J. Tarniewicz

    2012-05-01

    Full Text Available Eight years of occasional flask air sampling and 3 yr of frequent in situ measurements of carbon dioxide (CO2 vertical profiles on board of a small aircraft, over a tall tower greenhouse gases monitoring site in Hungary are used for the analysis of the variations of vertical profile of CO2 mole fraction. Using the airborne vertical profiles and the measurements along the 115 m tall tower it is shown that the measurements at the top of the tower estimate the mean boundary layer CO2 mole fraction during the mid-afternoon fairly well, with an underestimation of 0.27–0.85 μmol mol−1 in summer, and an overestimation of 0.66–1.83 μmol mol−1 in winter. The seasonal cycle of CO2 mole fraction is damped with elevation. While the amplitude of the seasonal cycle is 28.5 μmol mol−1 at 10 m above the ground, it is only 10.7 μmol mol−1 in the layer of 2500–3000 m corresponding to the lower free atmosphere above the well-mixed boundary layer. The maximum mole fraction in the layer of 2500–3000 m can be observed around 25 March on average, two weeks ahead of that of the marine boundary layer reference (GLOBALVIEW. By contrast, close to the ground, the maximum CO2 mole fraction is observed late December, early January. The specific seasonal behavior is attributed to the climatology of vertical mixing of the atmosphere in the Carpathian Basin.

  20. Intensity-Modulated Continuous-Wave Lidar Measurements of Surface Reflectance and Implications for CO2 Column Measurements: Results from 2013 ASCENDS Airborne Campaign

    Science.gov (United States)

    Nehrir, A. R.; Browell, E. V.; Harrison, F. W.; Dobler, J. T.; Lin, B.; Ismail, S.; Kooi, S. A.; Obland, M. D.

    2013-12-01

    Improved knowledge of the Earth's surface reflectance in the 1.57-micron spectral band is of particular importance for accurate Integrated Path Differential Absorption (IPDA) measurements and modeling of IPDA CO2 column measurements as required by the Active Sensing of CO2 Emission of Nights Days and Seasons (ASCENDS) Decadal Survey space mission. The Earth's surface albedo in the near-infrared portion of the spectrum is extremely low for snow and ice and for water under high wind conditions, and this can lead to degraded signal to noise ratios of surface reflectances and of IPDA CO2 column retrievals, requiring increased integration periods. This paper discusses the magnitude and variability of the surface reflectance and corresponding column CO2 measurements over snow measured using an intensity-modulated continuous-wave (IM-CW) laser absorption spectrometer (LAS), namely the Exelis Multi-function Fiber Laser Lidar (MFLL), during the winter 2013 ASCENDS airborne campaign. This LAS system is currently being evaluated by NASA Langley as the ASCENDS space mission prototype system. The surface reflectance measurements over snow and ice as well as over water collected during the 2013 winter DC-8 flight campaign were calibrated using surface reflectance data obtained over well-established satellite radiometric calibration sites such as Railroad Valley, Nevada and over other homogeneous desert sites in California and Arizona that have been used for similar calibrations on past ASCENDS airborne campaigns. Two separate flights targeting differences in surface reflectances between fresh and aged snow were conducted over the U.S. Central Plains and Colorado Rockies, respectively. From these measurements, the nominal surface reflectance of fresh snow (less than 1-2 days old; ~ 0.01/sr at 1.57 microns) was found to be approximately half that of aged snow (3-4 days old; ~ 0.02/sr) which is believed to be a result of increased absorption due to the snow water content. The

  1. Application of Relaxed Eddy Accumulation (REA) method to estimate CO2 and CH4 surface fluxes in the city of Krakow, southern Poland.

    Science.gov (United States)

    Zimnoch, Miroslaw; Gorczyca, Zbigniew; Pieniazek, Katarzyna; Jasek, Alina; Chmura, Lukasz; Rozanski, Kazimierz

    2013-04-01

    There is a growing interest in the recent years in studies aimed at quantifying carbon cycling in urban centres. Worldwide migration of human population from rural to urban areas and corresponding growth of extensive urban agglomerations and megacities leads to intensification of anthropogenic emissions of carbon and strong disruption of natural carbon cycle on these areas. Therefore, a deeper understanding of the carbon "metabolism" of such regions is required. Apart of better quantification of surface carbon fluxes, also a thorough understanding of the functioning of biosphere under strong anthropogenic influence is needed. Nowadays, covariance methods are widely applied for studying gas exchange between the atmosphere and the Earth's surface. Relaxed Eddy Accumulation method (REA), combined with the CO2 and CH4 CRDS analyser allows simultaneous measurements of surface fluxes of carbon dioxide and methane within the chosen footprint of the detection system, thus making possible thorough characterisation of the overall exchange of those gases between the atmosphere and the urban surface across diverse spatial and temporal scales. Here we present preliminary results of the study aimed at quantifying surface fluxes of CO2 and CH4 in Krakow, southern Poland. The REA system for CO2 and CH4 flux measurements has been installed on top of a 20m high tower mounted on the roof of the faculty building, close to the city centre of Krakow. The sensors were installed ca 42 m above the local ground. Gill Windmaster-Pro sonic anemometer was coupled with self-made system, designed by the Poznan University of Life Sciences, Poland, for collecting air samples in two pairs of 10-liter Tedlar bags, and with Picarro G2101-i CRDS analyser. The air was collected in 30-min intervals. The CO2 and CH4 mixing ratios in these cumulative downdraft and updraft air samples were determined by the CRDS analyser after each sampling interval. Based on the measured mixing ratios difference and the

  2. The investigations of nanoclusters and micron-sized periodic structures created at the surface of the crystal and amorphous silica by resonant CO2 laser irradiation

    Directory of Open Access Journals (Sweden)

    Mukhamedgalieva A.F.

    2017-01-01

    Full Text Available The creation of nanoclasters and micrometer sized periodical structures at the surface of silica (crystal quartz and fused quartz by action of pulsed CO2 laser radiation (pulse energy of 1 J, pulse time of 70 ns have been investigated. The laser action on the surface of samples lead to appearance of two kind of structures – periodical micron-sized structures with the period length close to wave length of CO2 laser irradiation and nanoclusters with size close to 50-100 nanometers. This creation connects with the intensive ablation of matter at the maxima of standing waves which are a results of the interference of falling and surfaces waves. This connects with the resonant absorption of infrared laser radiation by silicate minerals.

  3. The investigations of nanoclusters and micron-sized periodic structures created at the surface of the crystal and amorphous silica by resonant CO2 laser irradiation

    Science.gov (United States)

    Mukhamedgalieva, A. F.; Bondar, A. M.; Svedov, I. M.; Kononov, M. A.; Laptev, V. B.; Novikova, N. N.

    2016-12-01

    The creation of nanoclasters and micrometer sized periodical structures at the surface of silica (crystal quartz and fused quartz) by action of pulsed CO2 laser radiation (pulse energy of 1 J, pulse time of 70 ns) have been investigated. The laser action on the surface of samples lead to appearance of two kind of structures - periodical micron-sized structures with the period length close to wave length of CO2 laser irradiation and nanoclusters with size close to 50-100 nanometers. This creation connects with the intensive ablation of matter at the maxima of standing waves which are a results of the interference of falling and surfaces waves. This connects with the resonant absorption of infrared laser radiation by silicate minerals.

  4. Ikaite crystals in melting sea ice - implications for pCO(2) and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, Ronnie N.; Lennert, K.

    2012-01-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3 center dot 6H(2)O) in Arctic and Antarctic sea ice, which indicate...... that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km(2) (0.5-1m thick) drifting ice floe......, melt reduced the ice floe thickness by 0.2m per week and resulted in an estimated 3.8 ppm decrease of pCO(2) in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m(-2) sea ice d(-1) or to 3.3 ton km(-2) ice floe week(-1). This is markedly higher than the estimated...

  5. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-03-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from an actively melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures gradually disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice flow thickness by ca. 0.2 m per week and resulted in an estimated 1.6 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 11 mmol m−2 sea ice d−1 or to 3.5 ton km−2 ice floe week−1.

  6. The effect of CO2 laser irradiation plus fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement or composite resin restorations

    Science.gov (United States)

    Rodrigues, S. R.; Moraes, M.; Hanashiro, F. S.; Youssef, M. N.; Brugnera Junior, A.; Nobre-dos-Santos, M.; de Souza-Zaroni, W. C.

    2016-02-01

    Although the cariostatic effects of CO2 laser on the root surface have been shown, there is scarce information regarding its effects on root secondary caries. The objective of this research was to investigate the effect of the association of CO2 laser and a fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to composite-resin or glass-ionomer-cement restorations. Dental blocks of human roots were divided into two groups: composite resin (CR) or glass ionomer cement (GIC). Subsequently, the blocks were divided into four subgroups (n  =  10): C, non-fluoride dentifrice; FD, fluoride dentifrice; L, CO2 laser with an energy density of 6.0 J cm-2  +  non-fluoride dentifrice; and L  +  FD, CO2 laser  +  fluoride dentifrice. The blocks were subjected to pH cycling to simulate a high cariogenic challenge. Dental demineralization around the restorations was quantified by microhardness analysis. The results were subjected to analysis of variance (ANOVA) and the Tukey-Kramer test (p  ⩽  0.05). As for mineral loss, it can be observed that all the groups that were treated with a fluoride dentifrice and laser, used alone or not, were statistically similar and superior to the RC-C group. It was concluded that CO2 laser irradiation and a fluoride dentifrice used alone or combined with each other are efficient surface treatments for preventing secondary root caries, regardless of the restorative material used.

  7. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-08-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air–sea CO2 uptake of 10.6 mmol m−2 sea ice d−1 or to 3.3 ton km−2 ice floe week−1. This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m−2 sea ice d−1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  8. Potassium and Zeolitic Structure Modified Ultra-microporous Adsorbent Materials from a Renewable Feedstock with Favorable Surface Chemistry for CO2 Capture.

    Science.gov (United States)

    Liu, Xin; Sun, Yuan; Liu, Jingjing; Sun, Chenggong; Liu, Hao; Xue, Qian; Smith, Emily; Snape, Colin

    2017-08-16

    Novel hierarchically structured microporous biocarbons with exceptionally high capacities for CO2 capture have been synthesized from the abundant agricultural waste of rice husk (RH), using a facile methodology that effectively integrated carbonization, activation, and potassium intercalation into a one-step process. Textural characterization demonstrates that the synthesized biocarbons exhibit exceedingly high ultra-microporosity accounting for up to 95% of total porosity mainly as a result of the naturally occurring silicon compounds within the RH molecular framework structures. With a modest surface area of up to 1035 m(2)/g and a total pore volume of 0.43 cm(3)/g, the best performing RH carbon has shown exceptionally high and fully reversible CO2 uptake capacity of 2.0 mmol/g at 25 °C and a CO2 partial pressure of 0.15 bar, which represents one of the highest uptakes ever reported for both carbon and MOF materials usually prepared from using cost-prohibitive precursor materials with cumbersome methodologies. It has been found that up to 50% of the total CO2 uptake is attributable to the unique surface chemistry of the RH carbons, which appears to be dominated by the enhanced formation of extra-framework potassium cations owing to the exceedingly high levels of ultra-microporosity and the presence of zeolitic structures incorporated within the carbon matrices. Characterizations by EDX element mapping, XPS, and heat of adsorption measurements confirm the existence of a range of zeolitic structures, which essentially transforms the RH carbons into a kind of zeolite-carbon nanocomposite material with strong surface affinity for CO2.

  9. Response surface methodology as an approach to optimization of ethereal Oil from cassia by supercritical CO2 extraction%CO2超临界萃取桂皮精油工艺条件的优化

    Institute of Scientific and Technical Information of China (English)

    刘成国; 王冬冬; 陈瑶; 罗扬

    2011-01-01

    Cassia was used as raw material to extract ethereal oil using supercritical CO2 extraction.Scavenging effect of DPPH · (2,2-Diphenyl-l-Picryhydrazyl)was used as antioxidant activity index, based on single factor experiments, the optimal extraction process was determined using central composite design combined with response surface methodology.Optimal conditions of supereritical CO2 extraction of ethereal oil from cassia can be concluded as follows: Extraction pressure 33.5 MPa, extraction time 1.7 h, extraction temperature 60.5 ℃.On these conditions, the observed and predicted values of the scavenging effect of DPPH · were 84.98% and 85.17%.%以桂皮为原料,利用CO超临界萃取法提取桂皮精油.在单因素试验的基础上,以二苯代苦味酰基自由基清除率(2,2-Diphenyl-1-Picryhydrazyl,DPPH·)为抗氧化性指标,利用Box-Benhnken中心组合试验和响应面分析法,确定提取桂皮精油的最适工艺条件:萃取压力33.5 MPa,萃取时间1.7 h,萃取温度60.5℃.该条件下测得桂皮精油的DPPH·清除率为84.98%,预测值为85.17%.

  10. Comparative study of dentine permeability after apicectomy and surface treatment with 9.6 microm TEA CO2 and Er:YAG laser irradiation.

    Science.gov (United States)

    Gouw-Soares, S; Stabholz, A; Lage-Marques, J L; Zezell, D M; Groth, E B; Eduardo, C P

    2004-04-01

    Failure of apicectomies is generally attributed to dentine surface permeability as well as to the lack of an adequate marginal sealing of the retrofilling material, which allows the percolation of microorganisms and their products from the root canal system to the periodontal region, thus compromising periapical healing. The purpose of this study was to evaluate dentine and the marginal permeability after apicectomy and surface treatment with 9.6 micro m TEA CO(2) or Er:YAG 2.94 micro m laser irradiation. Sixty-five single rooted human endodontically treated teeth were divided into five experimental groups: group I (control), apicectomy with high speed bur; group II, similar procedure to that of group I, followed by dentinal surface treatment with 9.6 micro m CO(2) laser; group III, similar procedure to group I followed by dentinal surface treatment with Er:YAG laser 2.94 micro m; group IV, apicectomy and surface treatment with CO(2) 9.6 micro m laser; and group V, apicectomy and surface treatment with Er:YAG laser 2.94 micro m. The analysis of methylene blue dye infiltration through the dentinal surface and the retrofilling material demonstrated that the samples from the groups that were irradiated with the lasers showed significantly lower infiltration indexes than the ones from the control group. These results were compatible with the structural morphological changes evidenced through SEM analysis. Samples from groups II and IV (9.6 micro m CO(2)) showed clean smooth surfaces, fusion, and recrystallized dentine distributed homogeneously throughout the irradiated area sealing the dentinal tubules. Samples from groups III and V (Er:YAG 2.94 micro m) also presented clean surfaces, without smear layer, but roughly compatible to the ablationed dentine and without evidence of dentinal tubules. Through the conditions of this study, the Er:YAG 2.94 micro m and the 9.6 micro m CO(2) laser used for root canal resection and dentine surface treatment showed a reduction of

  11. Insight into the mechanism for the methanol synthesis via the hydrogenation of CO2 over a Co-modified Cu(100) surface: A DFT study

    Science.gov (United States)

    Qiu, Mei; Tao, Huilin; Li, Rong; Li, Yi; Huang, Xin; Chen, Wenkai; Su, Wenyue; Zhang, Yongfan

    2016-10-01

    A comprehensive density functional theory calculation was employed to investigate the reaction mechanism of methanol synthesis on a Co-modified Cu(100) surface via CO2 hydrogenation. The Cu(100) surface with embedded small Co clusters prepared experimentally was employed as a model system to explore the effects of Co dopant on the catalytic performance of Cu(100) surface towards CH3OH synthesis. The activation energy barriers and the reaction energies of 16 elementary surface reactions were determined. Our calculated results show that the most favorable reaction pathway for the hydrogenation of CO2 to CH3OH follows the sequence of CO2 → HCOO* →H2COO* →H2COOH* →H2CO* →H3CO* →H3COH*, and the OH* group hydrogenation to H2 O* is the rate-limiting step with an activation barrier of 112.3 kJ/mol. It is noted that, since the strength of Co-O bond is stronger than that of Cu-O bond, the introducing of Co dopant on the Cu surface can facilitate the formation of key intermediates for the CH3OH synthesis. Especially, the stability of the unstable dioxomethylene intermediate (H2COO*) found on the pure Cu(100) surface can be obviously enhanced on the Co-doped Cu(100) surface. As a result, with respect to the undoped surface, the productivity and selectivity towards CH3OH production on the Cu(100) surface will be improved after dispersing small Co clusters on the surface.

  12. Surface Gas Geochemistry above the Natural CO2 Reservoir of Montmiral (Drôme, France, Source Tracking and Gas Exchange between the Soil, Biosphere and Atmosphere Échanges gazeux et géochimie des gaz à la surface du réservoir naturel profond de CO2 de Montmiral (Drôme

    Directory of Open Access Journals (Sweden)

    Gal F.

    2010-07-01

    Full Text Available One of the options considered to mitigate greenhouse gas concentrations in the atmosphere is underground storage of CO2. There is a strong need for enhancing and developing methods that would help throughout the duration life of such underground storage, to ensure the safety and able to monitor the evolution of the injected CO2 plume. Among these, geochemical methods can play an important role. Here, we describe results acquired under the research programme “Géocarbone-Monitoring”, partially funded by the French National Research Agency, on the Montmiral natural analogue in South-Eastern France. Other results obtained under the same research programme in the French Massif Central are reported elsewhere in this volume. Spot sampling methods allowing a great geographical coverage and continuous measurements on selected points were undertaken in 2006 and 2007, in order to determine soil gas concentrations and fluxes as well as carbon isotope ratio determinations. One important result is that without any evidence of deep CO2 leakage, both CO2 concentrations and fluxes appear to be higher than can be explained only by biological activities. Further investigations are thus needed to understand the gas evolution better throughout the year. Une des options envisagées pour réguler les concentrations de gaz à effet de serre dans l’atmosphère est le stockage souterrain du CO2. Dans ce domaine existe un fort besoin de renforcer et de développer des méthodes susceptibles d’être utilisées tout au long de la durée de vie de ces stockages souterrains, afin de s’assurer de leur sécurité et de pouvoir suivre l’évolution du panache de CO2 injecté. Parmi elles, les méthodes géochimiques peuvent jouer un rôle important. Nous décrivons ici les résultats acquis dans le cadre du programme de recherche « Géocarbone-Monitoring » financé en partie par l’Agence Nationale de la Recherche sur l’analogue naturel de Montmiral dans le Sud

  13. Exchange of adsorbed H2O and CO2 between the regolith and atmosphere of Mars caused by changes in surface insolation

    Science.gov (United States)

    Fanale, F. P.; Cannon, W. A.

    1974-01-01

    Estimates have been made of the capacity of the Martian regolith to exchange adsorbed H2O and CO2 with the atmosphere-plus-cap system (APCS). These estimates are based upon measured isotherms for H2O and CO2 adsorption on pulverized basalt at low temperatures and on theoretical considerations. A unit column (1 sq cm) of regolith with a deep subsurface temperature of -77 C, considered average for the disk, will contain about 0.4 g of adsorbed CO2 and about 1 g of adsorbed H2O per meter of depth. Under favorable circumstances the top 3 cm can exchange much more H2O with the lower atmosphere each day than is necessary to produce the diurnal brightening. The process appears to be seasonally reversible. The total regolith may contain, in the adsorbed phase alone, as much as 1% of the H2O and 5% of the CO2 surface inventories expected for a hypothetical Mars that has experienced degassing as intensive as that of earth.

  14. Effect of a CO2 Laser on the Inhibition of Root Surface Caries Adjacent to Restorations of Glass Ionomer Cement or Composite Resin: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    L. C. Daniel

    2015-01-01

    Full Text Available This study investigated the effect of CO2 laser irradiation on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement (GIC or composite resin (CR restorations. 40 dental blocks were divided into 4 groups: G1 (negative control: cavity preparation + adhesive restoration with CR; G2: (positive control cavity preparation + GIC restoration; G3: equal to group 1 + CO2 laser with 6 J/cm2; G4: equal to group 2 + CO2 laser. The blocks were submitted to thermal and pH cycling. Dental demineralization around restorations was quantified using microhardness analyses and Light-Induced Fluorescence (QLF. The groups showed no significant differences in mineral loss at depths between 20 μm and 40 μm. At 60 μm, G2 and G3 ≠ G1, but G4 = G1, G2 and G3. At 80 μm, G4 ≠ G1, and at 100 μm, G4 = G2 = G1. At 140 and 220 μm, G2, G3, and G4 = G1. The averages obtained using QFL in groups 1, 2, 3, and 4 were 0.637, 0.162, 0.095, and 0.048, respectively. QLF and microhardness analyses showed that CO2 laser irradiation reduced mineral loss around the CR restorations but that it did not increase the anticariogenic effect of GIC restorations.

  15. Surface generation of a cobalt-derived water oxidation electrocatalyst developed in a neutral HCO3 -/CO2 system

    KAUST Repository

    Joya, Khurram Saleem

    2014-06-04

    Neutral HCO3 -/CO2 is a new electrolyte system for in situ generation of robust and efficient Co-derived (Co-Ci) water oxidation electrocatalysts. The Co-Ci/indium tin oxide system shows a remarkable 2.0 mA cm-2 oxygen evolution current density that is sustained for several hours. 7.5 nmol of electroactive species per cm2 generates about 109 μmol of O2 at a rate of 0.51 per mol of catalyst per second.

  16. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy

  17. CO2-Neutral Fuels

    Science.gov (United States)

    Goede, Adelbert; van de Sanden, Richard

    2016-06-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy efficiency.

  18. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy

  19. Generation of Cu–In alloy surfaces from CuInO2 as selective catalytic sites for CO2 electroreduction

    KAUST Repository

    Jedidi, Abdesslem

    2015-08-11

    The lack of availability of efficient, selective and stable electrocatalysts is a major hindrance for scalable CO2 reduction processes. Herein, we report the generation of Cu–In alloy surfaces for electrochemical reduction of CO2 from mixed metal oxides of CuInO2 as the starting material. The material successfully generates selective active sites to form CO from CO2 electroreduction at mild overpotentials. Density functional theory (DFT) indicates that the site occupation of the inert In occurs more on the specific sites of Cu. In addition, while In atoms do not preferentially adsorb H or CO, Cu atoms, which neighbor the In atoms, alters the preference of their adsorption. This preference for site occupation and altered adsorption may account for the improved selectivity over that observed for Cu metal. This study demonstrates an example of a scalable synthesis method of bimetallic surfaces utilized with the mixed oxide precursor having the diversity of metal choice, which may drastically alter the electrocatalytic performance, as presented herein.

  20. A comparison of cellulosic fuel yields and separated soil-surface CO2 fluxes in maize and prairie biofuel cropping systems

    Science.gov (United States)

    Nichols, Virginia A.

    It has been suggested that strategic incorporation of perennial vegetation into agricultural landscapes could provide ecosystem services while maintaining agricultural productivity. To evaluate potential use of prairie as a Midwestern cellulosic feedstock, we investigated theoretical cellulosic fuel yields, as well as soil-surface carbon dioxide emissions of prairie-based biofuel systems as compared to maize-based systems on fertile soils in Boone County, IA, USA. Investigated systems were: a maize-soybean rotation grown for grain only, continuous maize grown for grain and stover both with and without a winter rye cover crop, and a 31-species reconstructed prairie grown with and without spring nitrogen fertilization for fall-harvested biomass. From 2009-2013, the highest producing system was N-fertilized prairie, averaging 10.4 Mg ha -1 yr-1 above-ground biomass with average harvest removals of 7.8 Mg ha-1 yr-1. The unfertilized prairie produced 7.4 Mg ha-1 yr-1, averaging harvests of 5.3 Mg ha-1 yr-1. Lowest cellulosic biomass harvests were realized from continuous maize systems, averaging 3.5 Mg ha -1 yr-1 when grown with, and 3.7 Mg ha-1 yr-1 when grown without a winter rye cover crop, respectively. Un-fertilized prairie biomass and maize stover had equivalent dietary conversion ratios at 330 g ethanol kg-1 dry biomass, but N-fertilized prairie was lower at 315. Over four years prairie systems averaged 1287 L cellulosic ethanol ha-1 yr-1 more than maize systems, with fertilization increasing prairie ethanol production by 865 L ha-1 yr-1. Harvested biomass accounted for >90% of ethanol yield variation. A major hurdle in carbon cycling studies is the separation of the soil-surface CO2 flux into its respective components. From 2012-2013 we used a shading method to separate soil-surface CO2 resulting from oxidation of soil organic matter and CO2 derived from live-root activity in three systems: unfertilized prairie, N-fertilized prairie, and continuous maize

  1. Near Surface Gas Simulator (NSGS): A Visual Basic program to improve the design of near-surface gas geochemistry surveys above CO2 geological storage sites

    Science.gov (United States)

    Beaubien, S. E.; Annunziatellis, A.; Ciotoli, G.; Lombardi, S.

    2009-04-01

    If CO2 were to leak from a geological storage site and be released to the atmosphere, where would it occur and how large would the leak be in terms of dimension and flow rate? There are many options available to monitor storage sites, including deep and shallow geophysical or geochemical methods, biological markers, or remote sensing techniques, each with its advantages and disadvantages. However only the direct measurement of CO2 at the earth's surface, that is soil gas or gas flux analyses, can give a definitive answer to these questions. Considering that these methods involve point measurements, the question has be raised regarding the sampling density that would be needed to locate a leak above a storage site, or, conversely, to ensure that a leak does not exist. To address this issue we have written a program in Visual Basic which uses highly-detailed, gridded synthetic data (with user-defined gas leakage areas) to study the link between sampling density and anomaly size and to find a sampling strategy which minimises the number of samples collected while maximizing the probability that an anomaly (i.e. a leak) will be found. At the beginning of a run the user is asked to define the location, size, and intensity of leakage areas; these areas are then superimposed on a grid (1 x 1 m step size) of normally-distributed background CO2 flux values. Then the user is asked to provide a series of sampling densities (for example, x = 10, 50, 100, 500, and 1000 samples km-2) and the number of simulations that must be conducted for each sampling density (e.g. y = 100). The program then uses a nested loop structure whereby the synthetic dataset is randomly subsampled at the sampling density "x" for a total of "y" times - each of these smaller datasets is then analysed statistically and spatially using subroutines from the programs Statistica and Surfer, and the resultant data from each simulation for that "x" sampling density is combined to define its statistical

  2. Integrative Modeling of Caprock Integrity in the Context of CO2 Storage: Evolution of Transport and Geochemical Properties and Impact on Performance and Safety Assessment Modélisation intégrée de l’intégrité des roches de couverture dans le contexte du stockage du CO2 : évolution des propriétés de transport et impact sur les performances et la sûreté du stockage

    Directory of Open Access Journals (Sweden)

    Bildstein O.

    2010-06-01

    valuation de performance des couvertures et une étude de sûreté afin de s’assurer de leur préservation et de leur intégrité sur le long terme (de l’ordre du millénaire. L’objectif est, d’une part, d’aboutir à la construction d’un modèle phénoménologique multi-échelle global, puis à un modèle numérique décrivant le confinement du CO2 par les couvertures, et, d’autre part, de déterminer les performances du confinement en identifiant les processus clés et les paramètres les plus influents. Une première partie du programme a consisté en une intégration spatiale de l’ensemble des données phénoménologiques et structurales disponibles à la suite des travaux réalisés dans les différents volets (WP1 à WP4 et à la définition des scénarios types d’évolution du site de stockage (niveaux réservoirs et encaissants. Ce travail a permis de définir les cas tests à prendre en compte et de réaliser les calculs de performance par rapport aux scénarios d’injection et par rapport aux hétérogénéités majeures identifiées dans les niveaux de confinement (notamment les fractures. Les résultats montrent que l’injection de CO2 peut avoir un effet significatif, en altérant la porosité par dissolution et précipitation de minéraux, mais que l’impact est limité dans l’espace, de quelques décimètres à quelques mètres de l’interface réservoir-couverture, selon que la bulle de CO2 supercritique pénètre ou non dans la couverture et selon la présence ou l’absence de fractures. La prise en compte des résultats issus de l’analyse de sensibilité et l’analyse des incertitudes permettra de conduire des calculs de sûreté plus précis. Appliqués au futur site d’injection, ces calculs permettront d’évaluer la pérennité des propriétés de confinement des couvertures et de valider la qualité de confinement du site de stockage de CO2. Il conviendra notamment d’évaluer l’impact du couplage entre les phénomènes g

  3. Modelisation de la diffusion sur les surfaces metalliques: De l'adatome aux processus de croissance

    Science.gov (United States)

    Boisvert, Ghyslain

    Cette these est consacree a l'etude des processus de diffusion en surface dans le but ultime de comprendre, et de modeliser, la croissance d'une couche mince. L'importance de bien mai triser la croissance est primordiale compte tenu de son role dans la miniaturisation des circuits electroniques. Nous etudions ici les surface des metaux nobles et de ceux de la fin de la serie de transition. Dans un premier temps, nous nous interessons a la diffusion d'un simple adatome sur une surface metallique. Nous avons, entre autres, mis en evidence l'apparition d'une correlation entre evenements successifs lorsque la temperature est comparable a la barriere de diffusion, i.e., la diffusion ne peut pas etre associee a une marche aleatoire. Nous proposons un modele phenomenologique simple qui reproduit bien les resultats des simulations. Ces calculs nous ont aussi permis de montrer que la diffusion obeit a la loi de Meyer-Neldel. Cette loi stipule que, pour un processus active, le prefacteur augmente exponentiellement avec la barriere. En plus, ce travail permet de clarifier l'origine physique de cette loi. En comparant les resultats dynamiques aux resultats statiques, on se rend compte que la barriere extraite des calculs dynamiques est essentiellement la meme que celle obtenue par une approche statique, beaucoup plus simple. On peut donc obtenir cette barriere a l'aide de methodes plus precises, i.e., ab initio, comme la theorie de la fonctionnelle de la densite, qui sont aussi malheureusement beaucoup plus lourdes. C'est ce que nous avons fait pour plusieurs systemes metalliques. Nos resultats avec cette derniere approche se comparent tres bien aux resultats experimentaux. Nous nous sommes attardes plus longuement a la surface (111) du platine. Cette surface regorge de particularites interessantes, comme la forme d'equilibre non-hexagonale des i lots et deux sites d'adsorption differents pour l'adatome. De plus, des calculs ab initio precedents n'ont pas reussi a confirmer la

  4. Chemical Reaction CO+OH(•) → CO2+H(•) Autocatalyzed by Carbon Dioxide: Quantum Chemical Study of the Potential Energy Surfaces.

    Science.gov (United States)

    Masunov, Artëm E; Wait, Elizabeth; Vasu, Subith S

    2016-08-04

    The supercritical carbon dioxide medium, used to increase efficiency in oxy combustion fossil energy technology, may drastically alter both rates and mechanisms of chemical reactions. Here we investigate potential energy surface of the second most important combustion reaction with quantum chemistry methods. Two types of effects are reported: formation of the covalent intermediates and formation of van der Waals complexes by spectator CO2 molecule. While spectator molecule alter the activation barrier only slightly, the covalent bonding opens a new reaction pathway. The mechanism includes sequential covalent binding of CO2 to OH radical and CO molecule, hydrogen transfer from oxygen to carbon atoms, and CH bond dissociation. This reduces the activation barrier by 11 kcal/mol at the rate-determining step and is expected to accelerate the reaction rate. The finding of predicted catalytic effect is expected to play an important role not only in combustion but also in a broad array of chemical processes taking place in supercritical CO2 medium. It may open a new venue for controlling reaction rates for chemical manufacturing.

  5. A DFT study on surface dependence of β-Ga2O 3 for CO 2 hydrogenation to CH 3OH.

    Science.gov (United States)

    Qu, Jin; Tsang, Shik Chi Edman; Gong, Xue-Qing

    2014-12-01

    In this paper, the catalytic activities of various β-Ga2O3 surfaces for CO2 hydrogenation have been studied by density functional theory (DFT) calculations. The surface dependence of adsorptions and coadsorptions of reactants are investigated on two terminations of Ga2O3, which are Ga2O3(001) and Ga2O3(111). The active termination of Ga2O3(001) is identified and a surface structure rearrangement is determined. The thermodynamic profiles of surface intermediates involved in the reaction pathways for methanol formation are systematically calculated, and the initial key step of CO2 hydrogenation to bicarbonate is analyzed in detail. It has been found that the active Ga2O3(001) termination gives rise to a lower hydrogenation barrier largely due to the fact that saturated lattice O at Ga2O3(001) can act as a favorable site for both hydrogen adsorption and transfer while the unsaturated O at Ga2O3(111) is much less effective for these processes.

  6. CO2 -Responsive polymers.

    Science.gov (United States)

    Lin, Shaojian; Theato, Patrick

    2013-07-25

    This Review focuses on the recent progress in the area of CO2 -responsive polymers and provides detailed descriptions of these existing examples. CO2 -responsive polymers can be categorized into three types based on their CO2 -responsive groups: amidine, amine, and carboxyl groups. Compared with traditional temperature, pH, or light stimuli-responsive polymers, CO2 -responsive polymers provide the advantage to use CO2 as a "green" trigger as well as to capture CO2 directly from air. In addition, the current challenges of CO2 -responsive polymers are discussed and the different solution methods are compared. Noteworthy, CO2 -responsive polymers are considered to have a prosperous future in various scientific areas.

  7. Robust optimization of well location to enhance hysteretical trapping of CO2: Assessment of various uncertainty quantification methods and utilization of mixed response surface surrogates

    Science.gov (United States)

    Babaei, Masoud; Pan, Indranil; Alkhatib, Ali

    2015-12-01

    The paper aims to solve a robust optimization problem (optimization in presence of uncertainty) for finding the optimal locations of a number of CO2 injection wells for geological sequestration of carbon dioxide in a saline aquifer. The parametric uncertainties are the interfacial tension between CO2 and aquifer brine, the Land's trapping coefficient and the boundary aquifer's absolute permeability. The spatial uncertainties are due to the channelized permeability field which exhibits a binary channel-non-channel system. The objective function of the optimization is the amount of residually trapped CO2 due to the hysteresis of the relative permeability curves. A risk-averse value derived from the cumulative density function of the distribution of the amount of trapped gas is chosen as the objective function value. In order to ensure that the uncertainties are effectively taken into account, Monte Carlo simulation and Polynomial Chaos Expansion (PCE)-based methods are used and compared with each other. For different cases of parametric and spatial uncertainties, the most accurate uncertainty quantification (UQ) method is chosen to be integrated within the optimization algorithm. While for parametric uncertainty cases of up to two uncertain variables, PCE-based methods computationally outperform Monte Carlo simulations, it is shown that for the multimodal distributions of the function of trapped gas occurring for the spatial uncertainty case, Monte Carlo simulations are more reliable than PCE-based UQ methods. For the discrete (integer) optimization problem, various mixed response surface surrogate models are tested and the robust optimization resulted in optimal CO2 injection well locations.

  8. CO2 laser modeling

    Science.gov (United States)

    Johnson, Barry

    1992-01-01

    The topics covered include the following: (1) CO2 laser kinetics modeling; (2) gas lifetimes in pulsed CO2 lasers; (3) frequency chirp and laser pulse spectral analysis; (4) LAWS A' Design Study; and (5) discharge circuit components for LAWS. The appendices include LAWS Memos, computer modeling of pulsed CO2 lasers for lidar applications, discharge circuit considerations for pulsed CO2 lidars, and presentation made at the Code RC Review.

  9. Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

    Science.gov (United States)

    Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

    2009-09-01

    This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

  10. INTERACTION OF LASER RADIATION WITH MATTER: Influence of surface breakdown on the process of drilling metals with pulsed CO2 laser radiation

    Science.gov (United States)

    Arutyunyan, R. V.; Baranov, V. Yu; Bobkov, I. V.; Bol'shov, Leonid A.; Dolgov, V. A.; Kanevskiĭ, M. F.; Malyuta, D. D.; Mezhevov, V. S.

    1988-03-01

    A report is given of the influence of low-threshold surface optical breakdown, occurring under the action of short (~ 5-μs) radiation pulses from a CO2 laser, on the process of the laser drilling of metals. Data are given on the difference between the interaction of radiation pulses having the same duration but differing in shape. A study was made of the influence of the pressure of the atmosphere surrounding a target on the results of laser drilling of metals. A theoretical explanation is given of the experimental results.

  11. Impacts of land surface properties and atmospheric CO2 on the Last Glacial Maximum climate: a factor separation analysis

    Directory of Open Access Journals (Sweden)

    G. Munhoven

    2009-06-01

    Full Text Available Many sensitivity studies have been carried out, using climate models of different degrees of complexity to test the climate response to Last Glacial Maximum boundary conditions. Here, instead of adding the forcings successively as in most previous studies, we applied the separation method of U. Stein et P. Alpert 1993, in order to determine rigorously the different contributions of the boundary condition modifications, and isolate the pure contributions from the interactions among the forcings. We carried out a series of sensitivity experiments with the model of intermediate complexity Planet Simulator, investigating the contributions of the ice sheet expansion and elevation, the lowering of the atmospheric CO2 and of the vegetation cover change on the LGM climate. The separation of the ice cover and orographic contributions shows that the ice albedo effect is the main contributor to the cooling of the Northern Hemisphere, whereas orography has only a local cooling impact over the ice sheets. The expansion of ice cover in the Northern Hemisphere causes a disruption of the tropical precipitation, and a southward shift of the ITCZ. The orographic forcing mainly contributes to the disruption of the atmospheric circulation in the Northern Hemisphere, leading to a redistribution of the precipitation, but weakly impacts the tropics. The isolated vegetation contribution also induces strong cooling over the continents of the Northern Hemisphere that further affects the tropical precipitation and reinforce the southward shift of the ITCZ, when combined with the ice forcing. The combinations of the forcings generate many non-linear interactions that reinforce or weaken the pure contributions, depending on the climatic mechanism involved, but they are generally weaker than the pure contributions. Finally, the comparison between the LGM simulated climate and climatic reconstructions over Eurasia suggests that our results reproduce well the south-west to

  12. Impacts of land surface properties and atmospheric CO2 on the Last Glacial Maximum climate: a factor separation analysis

    Directory of Open Access Journals (Sweden)

    G. Munhoven

    2009-01-01

    Full Text Available Many sensitivity studies have been carried out, using simplified GCMs to test the climate response to Last Glacial Maximum boundary conditions. Here, instead of adding the forcings successively as in previous studies, we applied the separation method of Stein and Alpert (1993, in order to determine rigourously the different contributions of the boundary condition modifications, and isolate the pure contributions from the interactions among the forcings. We carried out a series of sensitivity experiments with the model of intermediate complexity Planet Simulator, investigating the contributions of the ice sheet expansion and elevation, the lowering of the atmospheric CO2 and of the vegetation cover change on the LGM climate. The results clearly identify the ice cover forcing as the main contributor to the cooling of the Northern Hemisphere, and also to the tropical precipitation disruption, leading to the shouthward shift of the ITCZ, while the orographic forcing mainly contributes to the disruption of the atmospheric circulation in the Northern Hemisphere. The isolated vegetation contribution also induces strong cooling over the continents of the Northern Hemisphere, that is further sufficient to affect the tropical precipitation and reinforce the southwards shift of the ITCZ, when combined with the ice forcing. The combinations of the forcings generate many non linear interactions, that reinforce or weaken the pure contributions, depending on the climatic mechanism involved, but they are generally weaker than the pure contributions. Finally, the comparison between the LGM simulated climate and climatic reconstructions over Eurasia suggests that our results reproduce well the south-west to north-east temperature gradients over Eurasia.

  13. A combination of CO2 laser and plasma surface modification of poly(etheretherketone) to enhance osteoblast response

    Science.gov (United States)

    Zheng, Yanyan; Xiong, Chengdong; Wang, Zhecun; Li, Xiaoyu; Zhang, Lifang

    2015-07-01

    Poly(etheretherketone) (PEEK) is a rigid semicrystalline polymer that combines excellent mechanical properties, broad chemical resistance and bone-like stiffness and is widely used in biomedical fields. However, the bio-inert surface of PEEK tends to hinder its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, we demonstrate a dual modification method, which combines the laser and plasma surface treatment to combine advantages of both chemical states and microstructures for osteoblasts responses. While the plasma treatment introduces surface carboxyl groups (sbnd COOH) onto PEEK surface, the laser treatment constructs microstructures over the PEEK surface. Our results indicated that sbnd COOH as well as microgrooves containing micropores or microcraters structure are constructed on PEEK surface and plasma treatment has no apparent effect on the morphology of microstructures produced by laser micromachining. Unexpectedly, the superior mechanical properties of PEEK were maintained irrespective of the treatment used. Compared to native PEEK and single treated PEEK, dual modified PEEK is more favorable for pre-osteoblasts (MC3T3-E1) adhesion, spreading and proliferation. Moreover, cell pseudopodia protrude into the micropores or microcraters, in favor of forming firmer bone-implant integration. Our study illustrates enhanced osteoblasts responses to dual treated PEEK surface, which gives beneficial information of its potential use in orthopedic or dental implants.

  14. 上海秋冬季地表能量平衡及CO 2通量特征分析%Characteristics of surface energy balance and CO 2 flux in autumn and winter in Shanghai

    Institute of Scientific and Technical Information of China (English)

    敖翔宇; 谈建国; 刘冬餠; 顾问; 胡平

    2014-01-01

    Based on eddy covariance observational data from November 11,2012 to January 20,2013 in Shanghai, diurnal variations of urban surface energy balance and carbon dioxide fluxes under different weather conditions were analyzed.The results show that under sunny and cloudy weather conditions,the maximum energy flux is stor-age heat,and then is convective transport of sensible heat,while the minimum fraction is latent heat used in evapo-ration and less than 50 W·m-2 .Daily storage heat flux has a peak at 1 1:00 a.m.which is earlier than that of net radiation flux,while it becomes negative before sunset.Diurnal curve of sensible heat flux is not symmetric around its peak,and its mean diurnal peak occurs in the early afternoon.Also,its value remains significantly positive after sunset.The Bowen ratio remains above 3 from noon to sunset.The effect of wind direction on sensible heat flux is the most significant.Under the dominant northwestly wind direction,daily peak value of sensible heat flux reduces from 175 W·m-2 (under other wind directions)to 120 W·m-2 .Haze and cloud show a negative effect on short-wave radiation,and effect of cloud is bigger than that of haze.The existence of cloud results in obvious reduction of upward and net long wave radiation,while it leads to an increase of the atmospheric downward longwave radia-tion.Carbon dioxide flux keeps positive values throughout the day under sunny weather condition,which means a constant carbon emission.There are two peaks for daily carbon dioxide fluxes,and both occurrence times are corre-sponding with morning and evening rush hours.Peak value of daily carbon dioxide flux is larger in the evening than in the morning.%利用2012年11月11日至2013年1月20日上海秋冬季涡动相关通量观测资料,对比分析地表能量平衡和CO2通量在不同天气条件下的日变化特征。结果表明:2012-2013年上海晴天和多云天气条件下,最大能量通量为储热项,其次为感热项;用

  15. Thermal desorption characteristics of CO, O2 and CO2 on non-porous water, crystalline water and silicate surfaces at sub-monolayer and multilayer coverages

    CERN Document Server

    Noble, J A; Dulieu, F; Fraser, H J

    2011-01-01

    The desorption characteristics of molecules on interstellar dust grains are important for modelling the behaviour of molecules in icy mantles and, critically, in describing the solid-gas interface. In this study, a series of laboratory experiments exploring the desorption of three small molecules from three astrophysically relevant surfaces are presented. The desorption of CO, O2 and CO2 at both sub-monolayer and multilayer coverages was investigated from non-porous water, crystalline water and silicate surfaces. Experimental data was modelled using the Polanyi-Wigner equation to produce a mathematical description of the desorption of each molecular species from each type of surface, uniquely describing both the monolayer and multilayer desorption in a single combined model. The implications of desorption behaviour over astrophysically relevant timescales are discussed.

  16. Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10-15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (Penamel layer after 5-10 seconds.

  17. Developing multi-tracer approaches to constrain the parameterisation of leaf and soil CO2 and H2O exchange in land surface models

    Science.gov (United States)

    Ogée, Jerome; Wehr, Richard; Commane, Roisin; Launois, Thomas; Meredith, Laura; Munger, Bill; Nelson, David; Saleska, Scott; Zahniser, Mark; Wofsy, Steve; Wingate, Lisa

    2016-04-01

    The net flux of carbon dioxide between the land surface and the atmosphere is dominated by photosynthesis and soil respiration, two of the largest gross CO2 fluxes in the carbon cycle. More robust estimates of these gross fluxes could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the carbon and oxygen isotope compositions (δ13C and δ18O) of atmospheric CO2. Over the past decades, the global atmospheric flask network has measured the inter-annual and intra-annual variations in the concentrations of these tracers. However, knowledge gaps and a lack of high-resolution multi-tracer ecosystem-scale measurements have hindered the development of process-based models that can simulate the behaviour of each tracer in response to environmental drivers. We present novel datasets of net ecosystem COS, 13CO2 and CO18O exchange and vertical profile data collected over 3 consecutive growing seasons (2011-2013) at the Harvard forest flux site. We then used the process-based model MuSICA (multi-layer Simulator of the Interactions between vegetation Canopy and the Atmosphere) to include the transport, reaction, diffusion and production of each tracer within the forest and exchanged with the atmosphere. Model simulations over the three years captured well the impact of diurnally and seasonally varying environmental conditions on the net ecosystem exchange of each tracer. The model also captured well the dynamic vertical features of tracer behaviour within the canopy. This unique dataset and model sensitivity analysis highlights the benefit in the collection of multi-tracer high-resolution field datasets and the developement of multi-tracer land surface models to provide valuable constraints on photosynthesis and respiration across scales in the near future.

  18. Release of N 2, CH 4, CO 2, and H 2O from surface ices on Enceladus

    Science.gov (United States)

    Hodyss, Robert; Goguen, Jay D.; Johnson, Paul V.; Campbell, Colin; Kanik, Isik

    2008-09-01

    We vapor deposit at 20 K a mixture of gases with the specific Enceladus plume composition measured in situ by the Cassini INMS [Waite, J.H., Combi, M.R., Ip, W.H., Cravens, T.E., McNutt, R.L., Kasprzak, W., Yelle, R., Luhmann, J., Niemann, H., Gell, D., Magee, B., Fletcher, G., Lunine, J., Tseng, W.L., 2006. Science 311, 1419-1422] to form a mixed molecular ice. As the sample is slowly warmed, we monitor the escaping gas quantity and composition with a mass spectrometer. Pioneering studies [Schmitt, B., Klinger, J., 1987. Different trapping mechanisms of gases by water ice and their relevance for comet nuclei. In: Rolfe, E.J., Battrick, B. (Eds.), Diversity and Similarity of Comets. SP-278. ESA, Noordwijk, The Netherlands, pp. 613-619; Bar-Nun, A., Kleinfeld, I., Kochavi, E., 1988. Phys. Rev. B 38, 7749-7754; Bar-Nun, A., Kleinfeld, I., 1989. Icarus 80, 243-253] have shown that significant quantities of volatile gases can be trapped in a water ice matrix well above the temperature at which the pure volatile ice would sublime. For our Enceladus ice mixture, a composition of escaping gases similar to that detected by Cassini in the Enceladus plume can be generated by the sublimation of the H 2O:CO 2:CH 4:N 2 mixture at temperatures between 135 and 155 K, comparable to the high temperatures inferred from the CIRS measurements [Spencer, J.R., Pearl, J.C., Segura, M., Flasar, F.M., Mamoutkine, A., Romani, P., Buratti, B.J., Hendrix, A.R., Spilker, L.J., Lopes, R.M.C., 2006. Science 311, 1401-1405] of the Enceladus "tiger stripes." This suggests that the gas escape phenomena that we measure in our experiments are an important process contributing to the gases emitted from Enceladus. A similar experiment for ice deposited at 70 K shows that both the processes of volatile trapping and release are temperature dependent over the temperature range relevant to Enceladus.

  19. Surface bioactivity modification of titanium by CO 2 plasma treatment and induction of hydroxyapatite: In vitro and in vivo studies

    Science.gov (United States)

    Hu, Xixue; Shen, Hong; Shuai, Kegang; Zhang, Enwei; Bai, Yanjie; Cheng, Yan; Xiong, Xiaoling; Wang, Shenguo; Fang, Jing; Wei, Shicheng

    2011-01-01

    Since metallic biomaterials used for orthopedic and dental implants possess a paucity of reactive functional groups, bioactivity modification of these materials is challenging. In the present work, the titanium discs and rods were treated with carbon dioxide plasma and then incubated in a modified simulated body fluid 1.5SBF to obtain a hydroxyapatite layer. Surface hydrophilicity of samples, changes of surface chemistry, surface morphologies of samples, and structural analysis of formed hydroxyapatite were investigated by contact angle to water, X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The results demonstrated that hydrophilicity of titanium surface was improved and hydroxyl groups increased after modification with carbon dioxide plasma treatment. The hydroxyl groups on the surface of titanium were the richest after carbon dioxide plasma treatment under the condition of 20 W for less than 30 s. The hydroxyapatite formability of titanium surface was enhanced by carbon dioxide plasma pretreatment, which was attributed to the surface chemistry. MC3T3-E1 cell as a model cell was cultured on the Ti, CPT-Ti and CPT/SBF-Ti discs in vitro, and the results of the morphology and differentiation of the cell showed that CPT/SBF-Ti was the highest bioactive. The relative parameters of the new bone around the Ti and CPT/SBF-Ti rods including bone mineral density (BMD), a ratio of bone volume to total volume (BV/TV), trabecular thickness (Tb.Th.) and trabecular number (Tb.N.) were analyzed by a micro-computed tomography (micro-CT) after 4-, 8- and 12-week implantation periods in vivo. The results indicated that the CPT/SBF-Ti was more advantageous for new bone formation.

  20. Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers

    Science.gov (United States)

    Del Rosso, T.; Rey, N. A.; Rosado, T.; Landi, S.; Larrude, D. G.; Romani, E. C.; Freire Junior, F. L.; Quinteiro, S. M.; Cremona, M.; Aucelio, R. Q.; Margheri, G.; Pandoli, O.

    2016-06-01

    Colloidal suspensions of oxocarbon-encapsulated gold nanoparticles have been synthesized in a one-step procedure by pulsed-laser ablation (PLA) at 532 nm of a solid gold target placed in aqueous solution containing CO2 absorbers, but without any stabilizing agent. Multi-wavelength surface enhanced Raman spectroscopy allows the identification of adsorbed amorphous carbon and graphite, Au-carbonyl, Au coordinated CO2-derived bicarbonates/carbonates and hydroxyl groups around the AuNPs core. Scanning electron microscopy, energy dispersive x-ray analysis and high resolution transmission electron microscopy highlight the organic shell structure around the crystalline metal core. The stability of the colloidal solution of nanocomposites (NCs) seems to be driven by solvation forces and is achieved only in neutral or basic pH using monovalent hydroxide counter-ions (NaOH, KOH). The NCs are characterized by a blue shift of the localized surface plasmon resonance (LSPR) band typical of metal-ligand stabilization by terminal π-back bonding, attributed to a core charging effect caused by Au-carbonyls. Total organic carbon measurements detect the final content of organic carbon in the colloidal solution of NCs that is about six times higher than the value of the water solution used to perform PLA. The colloidal dispersions of NCs are stable for months and are applied as analytical probes in amino glycoside antibiotic LSPR based sensing.

  1. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, R.N.; Lennert, K.

    2012-01-01

    chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5-1 m thick) drifting ice floe in the Fram Strait...... during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced...... within the ice floe of 0.3-1.3 mmol m -2 sea ice d -1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO 2 uptake. © Author(s) 2012....

  2. Monitoring Options for CO2 Storage

    NARCIS (Netherlands)

    Arts, R.; Winthaegen, P.

    2005-01-01

    This chapter provides an overview of various monitoring techniques for CO2 storage that is structured into three categories-instrumentation in a well (monitoring well); instrumentation at the (near) surface (surface geophysical methods); and sampling at the (near) surface measuring CO2 concentration

  3. Surface Properties of Poly[2-perfluorooctyl)ethyl acrylate] Deposited from Liquid CO2 High-Pressure Fee Meniscus Coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim,J.; Efimenko, K.; Genzer, J.; Carbonell, R.

    2007-01-01

    The surface characteristics of poly[2-(perfluorooctyl)ethyl acrylate] (PFOEA) films deposited using a high-pressure free meniscus coating (hFMC) process with liquid CO{sub 2} (l-CO{sub 2}) as the coating solvent on 12.5 cm diameter silicon wafer substrates were investigated using contact angle measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy. The results were compared with surface property measurements of PFOEA films deposited from 1,1,2-trichlorotrifluoroethane (Freon 113) under normal dip coating conditions at atmospheric pressure. NEXAFS measurements showed that perfluoroalkyl groups in the films from l-CO{sub 2} and Freon 113 were well-organized and oriented normal to the substrate at the air/polymer interface. AFM images and XPS measurements revealed that a terrace-like structure of the PFOEA film from l-CO{sub 2} resulted in carbonyl group exposure at the air/polymer interface. This leads to smaller contact angles on the films cast from l-CO{sub 2} relative to the specimens deposited from Freon 113. Annealing the films deposited from the solvents resulted in droplet formation on the surface due to dewetting. The critical surface tension ({gamma}{sub c}) after annealing the film prepared from Freon 113 increased from 6.5 to 8.5 mJ/m{sup 2}, whereas {gamma}{sub c} of the film deposited from l-CO{sub 2} decreased slightly from 9.7 to 8.9 mJ/m{sup 2}. We discuss how surface morphology changes before and after annealing play a role in the variation of {gamma}{sub c}.

  4. The optimization of essential oils supercritical CO2 extraction from Lavandula hybrida through static-dynamic steps procedure and semi-continuous technique using response surface method.

    Science.gov (United States)

    Kamali, Hossein; Aminimoghadamfarouj, Noushin; Golmakani, Ebrahim; Nematollahi, Alireza

    2015-01-01

    The aim of this study was to examine and evaluate crucial variables in essential oils extraction process from Lavandula hybrida through static-dynamic and semi-continuous techniques using response surface method. Essential oil components were extracted from Lavandula hybrida (Lavandin) flowers using supercritical carbon dioxide via static-dynamic steps (SDS) procedure, and semi-continuous (SC) technique. Using response surface method the optimum extraction yield (4.768%) was obtained via SDS at 108.7 bar, 48.5°C, 120 min (static: 8×15), 24 min (dynamic: 8×3 min) in contrast to the 4.620% extraction yield for the SC at 111.6 bar, 49.2°C, 14 min (static), 121.1 min (dynamic). The results indicated that a substantial reduction (81.56%) solvent usage (kg CO2/g oil) is observed in the SDS method versus the conventional SC method.

  5. Multi-Criteria Analysis of Laser Cut Surface Characteristics in CO2 Laser Cutting of Stainless Steel

    Directory of Open Access Journals (Sweden)

    M. Radovanović

    2015-06-01

    Full Text Available In this paper an approach for multi-criteria analysis of laser cut surface characteristics using multi-criteria decision making (MCDM approach was presented. Laser cutting experiment was conducted based on Taguchi’s L27 experimental design by varying laser power, cutting speed, assist gas pressure and focus position at three levels. Multi-criteria analysis was performed by using the weighted aggregated sum product assessment (WASPAS method while considering burr height, drag line separation, depth of separation line, surface roughness and perpendicularity of the cut as assessment criteria. Based on conducted experimental investigation the MCDM model with 27 alternatives (laser cuts and five criteria was developed. The relative importance of criteria was determined by using pair-wise comparison matrix and geometric mean method of the analytic hierarchy process (AHP method.

  6. Fabrication of microfluidic devices: improvement of surface quality of CO2 laser machined poly(methylmethacrylate) polymer

    Science.gov (United States)

    Mohammed, Mazher I.; Nazrul Hisham Zainal Alam, Muhd; Kouzani, Abbas; Gibson, Ian

    2017-01-01

    Laser engraving has considerable potential for the rapid and cost effective manufacturing of polymeric microfluidic devices. However, fabricated devices are hindered by relatively large surface roughness in the engraved areas, which can perturb smooth fluidic flow and can damage sensitive biological components. This effect is exacerbated when engraving at depths beyond the laser focal range, limiting the production of large aspect ratio devices such as microbioreactors. This work aims to overcome such manufacturing limitations and to realise more reproducible and defect free microfluidic channels and structures. We present a strategy of multiple engraving passes alongside solvent polymer reflow for shallow depth (500 µm) features. To examine the proposed methodologies, capillary action and bioreactor microfluidic devices were fabricated and evaluated. Results indicate that the multiple engraving technique could reproduce engraved microfluidic channels to depths between 50-470 µm, both rapidly (6-8 min) and with low average surface roughness (1.5-2.5 µm). The layer cutting approach was effective at manufacturing microfluidic devices with depths  <500 µm, rapidly (<1 min) and with low surface roughness. Ultimately, the proposed methodology is highly beneficial for the rapid development of polymer-based microfluidic devices.

  7. Regional CO2 and latent heat surface fluxes in the Southern Great Plains: Measurements, modeling, and scaling

    Energy Technology Data Exchange (ETDEWEB)

    Riley, W. J.; Biraud, S.C.; Torn, M.S.; Fischer, M.L.; Billesbach, D.P.; Berry, J.A.

    2009-08-15

    Characterizing net ecosystem exchanges (NEE) of CO{sub 2} and sensible and latent heat fluxes in heterogeneous landscapes is difficult, yet critical given expected changes in climate and land use. We report here a measurement and modeling study designed to improve our understanding of surface to atmosphere gas exchanges under very heterogeneous land cover in the mostly agricultural U.S. Southern Great Plains (SGP). We combined three years of site-level, eddy covariance measurements in several of the dominant land cover types with regional-scale climate data from the distributed Mesonet stations and Next Generation Weather Radar precipitation measurements to calibrate a land surface model of trace gas and energy exchanges (isotope-enabled land surface model (ISOLSM)). Yearly variations in vegetation cover distributions were estimated from Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index and compared to regional and subregional vegetation cover type estimates from the U.S. Department of Agriculture census. We first applied ISOLSM at a 250 m spatial scale to account for vegetation cover type and leaf area variations that occur on hundred meter scales. Because of computational constraints, we developed a subsampling scheme within 10 km 'macrocells' to perform these high-resolution simulations. We estimate that the Atmospheric Radiation Measurement Climate Research Facility SGP region net CO{sub 2} exchange with the local atmosphere was -240, -340, and -270 gC m{sup -2} yr{sup -1} (positive toward the atmosphere) in 2003, 2004, and 2005, respectively, with large seasonal variations. We also performed simulations using two scaling approaches at resolutions of 10, 30, 60, and 90 km. The scaling approach applied in current land surface models led to regional NEE biases of up to 50 and 20% in weekly and annual estimates, respectively. An important factor in causing these biases was the complex leaf area index (LAI) distribution

  8. Optimization for supercritical CO2 extraction of tilapia fish head oil by response surface method%响应面优化超临界CO2萃取罗非鱼头油的研究

    Institute of Scientific and Technical Information of China (English)

    张春华; 包斌; 陈山乔; 沈晶晶; 潘镜; 陶宁萍; 吴文惠

    2015-01-01

    为优化罗非鱼头油的提取工艺,通过单因素试验选择超临界CO2萃取罗非鱼头油的单因素水平,采用响应面法优化超临界CO2萃取罗非鱼头油的工艺条件,分析了罗非鱼头油的品质及脂肪酸组成.结果表明:超临界CO2技术萃取罗非鱼头油的最优工艺条件是压力36 MPa、温度41℃和时间3.1h,超临界CO2流体技术优于蒸煮法、碱水解法和酶解法;罗非鱼头油的最大提取率是79.5%,其碘值、过氧化值和酸值分别是(5.36-0.15) mg/kg、(4.27±0.33) mmol/kg、(139.0±8.9)g/l00g;罗非鱼头油的饱和脂肪酸(saturated fatty acid,SFA)、单不饱和脂肪酸(monounsaturated fatty acid,MUFA)和多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)的含量分别是27.85%,41.74%和30.41%,罗非鱼头油丰富的脂肪酸构成暗示着其优良的营养价值和功能性.

  9. CO2NNIE

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin

    2015-01-01

    We propose a system for calculating the personalized annual fuel consumption and CO2 emissions from transportation. The system, named CO2NNIE, estimates the fuel consumption on the fastest route between the frequent destinations of the user. The travel time and fuel consumption estimated are based......% of the actual fuel consumption (4.6% deviation on average). We conclude, that the system provides new detailed information on CO2 emissions and fuel consumption for any make and model....

  10. Wearable CO2 sensor

    OpenAIRE

    Radu, Tanja; Fay, Cormac; Lau, King-Tong; Waite, Rhys; Diamond, Dermot

    2009-01-01

    High concentrations of CO2 may develop particularly in the closed spaces during fires and can endanger the health of emergency personnel by causing serious physiological effects. The proposed prototype provides real-time continuous monitoring of CO2 in a wearable configuration sensing platform. A commercially available electrochemical CO2 sensor was selected due to its selectivity, sensitivity and low power demand. This was integrated onto an electronics platform that performed signal capture...

  11. Surface temperature, salinity, and pCO2 collected by bottle casts during a cruise in the north Atlantic Ocean from 9/3/1991 - 9/22/1991 (NODC Accession 0000113)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface temperature, salinity, and pCO2 data were collected using bottle casts from METEOR in the North Atlantic Ocean. Data were collected from 03 September 1991 to...

  12. Coupled Vadose Zone and Atmospheric Surface-Layer Transport of CO2 from Geologic Carbon Sequestration Sites

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curtis M.; Unger, Andre J.A.

    2004-03-29

    Geologic carbon dioxide (CO{sub 2}) sequestration is being considered as a way to offset fossil-fuel-related CO{sub 2} emissions to reduce the rate of increase of atmospheric CO{sub 2} concentrations. The accumulation of vast quantities of injected carbon dioxide (CO{sub 2}) in geologic sequestration sites may entail health and environmental risks from potential leakage and seepage of CO{sub 2} into the near-surface environment. We are developing and applying a coupled subsurface and atmospheric surface-layer modeling capability built within the framework of the integral finite difference reservoir simulator TOUGH2. The overall purpose of modeling studies is to predict CO{sub 2} concentration distributions under a variety of seepage scenarios and geologic, hydrologic, and atmospheric conditions. These concentration distributions will provide the basis for determining above-ground and near-surface instrumentation needs for carbon sequestration monitoring and verification, as well as for assessing health, safety, and environmental risks. A key feature of CO{sub 2} is its large density ({rho} = 1.8 kg m{sup -3}) relative to air ({rho} = 1.2 kg m{sup -3}), a property that may allow small leaks to cause concentrations in air above the occupational exposure limit of 4 percent in low-lying and enclosed areas such as valleys and basements where dilution rates are low. The approach we take to coupled modeling involves development of T2CA, a TOUGH2 module for modeling the multicomponent transport of water, brine, CO{sub 2}, gas tracer, and air in the subsurface. For the atmospheric surface-layer advection and dispersion, we use a logarithmic vertical velocity profile to specify constant time-averaged ambient winds, and atmospheric dispersion approaches to model mixing due to eddies and turbulence. Initial simulations with the coupled model suggest that atmospheric dispersion quickly dilutes diffuse CO{sub 2} seepage fluxes to negligible concentrations, and that rainfall

  13. On the relative influence of initial H2O and CO2 contents on the primitive surface conditions and evolution of rocky (exo-)planets

    Science.gov (United States)

    Salvador, Arnaud; Massol, Helène; Davaille, Anne; Marcq, Emmanuel; Chassefière, Eric; Sarda, Philippe

    2017-04-01

    Estimates of initial volatile contents inside planets primitive magma oceans (hereafter « MO ») varies by several orders of magnitude. However, the release of greenhouse gasses such as H2O and CO2 during cooling and crystallization of the MO will greatly affect the atmosphere formation, the planet cooling time scale, its surface temperature, and its potential for water condensation and habitability. We have therefore conducted a systematic study of the influence of volatile contents on the secular convective cooling and solidification of a MO in interaction with the outgassed atmosphere. We developed a 1D model coupling MO dynamics with a convective-radiative atmosphere using either a grey approximation or k-correlated opacities, with or without clouds. Initial CO2 and H2O contents were varied between 10-3 and 14×10-2 wt%, and from 0.05 to 2.2 times the Earth Ocean current mass (MEO). We considered an Earth-like planet, with its Sun intensity ranging from half to the present-day value and a solar distance from 0.63 to 1.30 AU. The atmosphere albedo was varied between 0.2 and 0.8. All cases shows the same evolution in two main episodes : after (1) a very rapid cooling stage driven by the MO cooling and crystallization, the planet reaches (2) a quasi-steady state where subsequent evolution will take billions of years. The surface temperature is controlled by the balance between the IR outgoing flux, and the heat flux out of the MO during (1), and the solar flux during (2). At the end of the first regime (hereafter « ERCS »), the planetary surface can (i) still be molten or partially-molten, (ii) solid but dry, (iii) solid and covered by a water ocean, depending on the initial volatile contents, sun characteristics and sun-planet distance. Regimes diagrams were obtained. There is a critical sun-planet distance Dc below which water will never condense, whatever the initial volatile content. For distances larger than Dc, water condensation strongly depends on the

  14. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, R.N.; Lennert, K.

    2012-01-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3•6H 2O) in Arctic and Antarctic sea ice, which indicate that multiple...... chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5-1 m thick) drifting ice floe in the Fram Strait...... during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced...

  15. Localization of a continuous CO2 leak from an isotropic flat-surface structure using acoustic emission detection and near-field beamforming techniques

    Science.gov (United States)

    Yan, Yong; Cui, Xiwang; Guo, Miao; Han, Xiaojuan

    2016-11-01

    Seal capacity is of great importance for the safety operation of pressurized vessels. It is crucial to locate the leak hole timely and accurately for reasons of safety and maintenance. This paper presents the principle and application of a linear acoustic emission sensor array and a near-field beamforming technique to identify the location of a continuous CO2 leak from an isotropic flat-surface structure on a pressurized vessel in the carbon capture and storage system. Acoustic signals generated by the leak hole are collected using a linear high-frequency sensor array. Time-frequency analysis and a narrow-band filtering technique are deployed to extract effective information about the leak. The impacts of various factors on the performance of the localization technique are simulated, compared and discussed, including the number of sensors, distance between the leak hole and sensor array and spacing between adjacent sensors. Experiments were carried out on a laboratory-scale test rig to assess the effectiveness and operability of the proposed method. The results obtained suggest that the proposed method is capable of providing accurate and reliable localization of a continuous CO2 leak.

  16. Electron Induced Surface Reactions of cis-Pt(CO)2Cl2: A Route to Focused Electron Beam Induced Deposition of Pure Pt Nanostructures.

    Science.gov (United States)

    Spencer, Julie A; Wu, Yung-Chien; McElwee-White, Lisa; Fairbrother, D Howard

    2016-07-27

    Using mechanistic data from surface science studies on electron-induced reactions of organometallic precursors, cis-Pt(CO)2Cl2 (1) was designed specifically for use in focused electron beam induced deposition (FEBID) of Pt nanostructures. Electron induced decomposition of adsorbed 1 under ultrahigh vacuum (UHV) conditions proceeds through initial CO loss as determined by in situ X-ray photoelectron spectroscopy and mass spectrometry. Although the Pt-Cl bonds remain intact during the initial decomposition step, larger electron doses induce removal of the residual chloride through an electron-stimulated desorption process. FEBID structures created from cis-Pt(CO)2Cl2 under steady state deposition conditions in an Auger spectrometer were determined to be PtCl2, free of carbon and oxygen. Coupled with the electron stimulated removal of chlorine demonstrated in the UHV experiments, the Auger deposition data establish a route to FEBID of pure Pt. Results from this study demonstrate that structure-activity relationships can be used to design new precursors specifically for FEBID.

  17. No More HF: Teflon-Assisted Ultrafast Removal of Silica to Generate High-Surface-Area Mesostructured Carbon for Enhanced CO2 Capture and Supercapacitor Performance.

    Science.gov (United States)

    Singh, Dheeraj Kumar; Krishna, Katla Sai; Harish, Srinivasan; Sampath, Srinivasan; Eswaramoorthy, Muthusamy

    2016-02-01

    An innovative technique to obtain high-surface-area mesostructured carbon (2545 m(2)  g(-1)) with significant microporosity uses Teflon as the silica template removal agent. This method not only shortens synthesis time by combining silica removal and carbonization in a single step, but also assists in ultrafast removal of the template (in 10 min) with complete elimination of toxic HF usage. The obtained carbon material (JNC-1) displays excellent CO2 capture ability (ca. 26.2 wt % at 0 °C under 0.88 bar CO2 pressure), which is twice that of CMK-3 obtained by the HF etching method (13.0 wt %). JNC-1 demonstrated higher H2 adsorption capacity (2.8 wt %) compared to CMK-3 (1.2 wt %) at -196 °C under 1.0 bar H2 pressure. The bimodal pore architecture of JNC-1 led to superior supercapacitor performance, with a specific capacitance of 292 F g(-1) and 182 F g(-1) at a drain rate of 1 A g(-1) and 50 A g(-1) , respectively, in 1 m H2 SO4 compared to CMK-3 and activated carbon.

  18. Monitoring subsurface CO2 storage

    NARCIS (Netherlands)

    Winthaegen, P.; Arts, R.; Schroot, B.M.

    2005-01-01

    An overview is given of various currently applied monitoring techniques for CO2 storage. Techniques are subdivided in correspondence to their applicability for monitoring three distinct realms. These are: - the atmosphere and the near-surface; - the overburden (including faults and wells); - the

  19. Modeling the effects of topography and wind on atmospheric dispersion of CO2 surface leakage at geologic carbon sequestration sites

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Fotini K.; Granvold, Patrick W.; Oldenburg, Curtis M.

    2008-11-01

    Understanding the potential impacts of unexpected surface releases of CO{sub 2} is an essential part of risk assessment for geologic carbon sequestration sites. We have extended a mesoscale atmospheric model to model dense gas dispersion of CO{sub 2} leakage. The hazard from CO{sub 2} leakage is greatest in regions with topographic depressions where the dense gas can pool. Simulation of dispersion in idealized topographies shows that CO{sub 2} can persist even under high winds. Simulation of a variety of topographies, winds, and release conditions allows the generation of a catalog of simulation results that can be queried to estimate potential impacts at actual geologic carbon sequestration sites.

  20. Three-year Variations of Water, Energy and CO2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China

    Institute of Scientific and Technical Information of China (English)

    LIU Huizhi; TU Gang; FU Congbin; SHI Liqing

    2008-01-01

    Based on 3 years (2003-05) of the eddy covariance (EC) observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu (44°25'N, 122°52'E, 184 m a.s.l.), Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer (at 0.05, 0.10 and 0.20 m) clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet (growing season) and dry seasons (non-growing season). During the growing season (from May to September), the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area.

  1. CO2 blood test

    Science.gov (United States)

    Bicarbonate test; HCO3-; Carbon dioxide test; TCO2; Total CO2; CO2 test - serum ... Many medicines can interfere with blood test results. Your health care provider will tell you if you need to stop taking any medicines before you have this test. DO ...

  2. CO2 laser resurfacing.

    Science.gov (United States)

    Fitzpatrick, R E

    2001-07-01

    The CO2 Laser offers a variety of unique features in resurfacing facial photodamage and acne scarring. These include hemostasis, efficient removal of the epidermis in a single pass, thermally induced tissue tightening, and safe, predictable tissue interaction. Knowledge of these mechanisms will result in the capability of using the CO2 laser effectively and safely whether the goal is superficial or deep treatment.

  3. Hybridization of Response Surface Methodology and Genetic Algorithm optimization for CO2 laser cutting parameter on AA6061 material

    Directory of Open Access Journals (Sweden)

    A.Parthiban

    2014-03-01

    Full Text Available Investigation of laser cutting parameters on aluminium alloy (AA6061 is important due to its high reflectivity and thermal conductivity. Generally Aluminium alloy is a widely used material in aeronautical and automation industries for its inherent properties. Although the main problem during laser cutting is occurrence of recasting layer and laser beam incidence that affecting the cutting quality is known as kerf dimensions. In a sense the relationship between the laser cutting parameters such as laser power, cutting speed, gas pressure and focal position with kerf dimensions are having important role in laser cutting operation. So this work considers the response surface methodology (RSM, for making empirical relationship between dependent and independent variables. Simultaneously, this work reveals that laser power, cutting speed, gas pressure and focal position have significant effects on kerf dimension. Thus the development of empirical model and the selection of best parameters are important for manufacturing industries. Hence this work develops the statistical model with RSM and optimizes the cutting parameters with genetic algorithm (GA.

  4. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    Energy Technology Data Exchange (ETDEWEB)

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

    2010-10-21

    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  5. Outsourcing CO2 Emissions

    Science.gov (United States)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  6. Reaction Mechanisms for the Electrochemical Reduction of CO2 to CO and Formate on the Cu(100) Surface at 298K from Quantum Mechanics Free Energy Calculations with Explicit Water.

    Science.gov (United States)

    Cheng, Tao; Xiao, Hai; Goddard, William A

    2016-10-11

    Copper is the only elemental metal that reduces a significant fraction of CO2 to hydrocarbons and alcohols, but the atomistic reaction mechanism that controls the product distributions are not known because it has not been possible to detect the reaction intermediates on the electrode surface experimentally, or carry out Quantum Mechanics (QM) calculations with a realistic description of the electrolyte (water). Here, we carry out Quantum Mechanics (QM) calculations with an explicit description of water on the Cu(100) surface (experimentally shown to be stable under CO2RR conditions) to examine the initial reaction pathways to form CO and formate (HCOO(-)) from CO2 through free energy calculations at 298K and pH 7. We find that CO formation proceeds from physisorbed CO2 to chemisorbed CO2 (*CO2(δ-)), with a free energy barrier of ΔG(‡)=0.43 eV, the rate determining step (RDS). The subsequent barriers of protonating *CO2(δ-) to form COOH* and then dissociating COOH* to form *CO are 0.37 eV and 0.30 eV, respectively. HCOO(-) formation proceeds through a very different pathway in which physisorbed CO2 reacts directly with a surface H* (along with electron transfer), leading to ΔG(‡) = 0.80 eV. Thus, the competition between CO formation and HCOO(-) formation occurs in the first electron transfer step. On Cu(100), the RDS for CO formation is lower, making CO the predominant product. Thus, to alter the product distribution we need to control this first step of CO2 binding, which might involve alloying or changing the structure at the nanoscale.

  7. 反应时间对CO2处理镁钙砖表面的影响%Influence of reaction time on CO2 treated magnesia-calcia brick surface

    Institute of Scientific and Technical Information of China (English)

    李国华; 陈树江; 崔研; 田琳

    2013-01-01

    为了解决镁钙砖的水化问题,采用CO2对其进行表面处理.在水汽温度40℃、试验温度700 ℃、CO2流量4 L·min-1的条件下研究了不同反应时间(0 ~ 240 min)对镁钙砖表面的影响,利用扫描电镜检测表面生成物和反应层厚度,并采用煮沸试验法检测抗水化效果.结果表明:经CO2处理后的镁钙砖表面可生成CaCO3保护膜;随着反应时间的延长,试样表面的反应层厚度逐渐增加,当反应时间为180 min时,试样表面反应层厚度达110.5 μm,抗水化效果最好.%The specimens were prepared using fused magnesia,high purity magnesia,α-AI2O3 micropowder and Cr2O3 micropowder as main starting materials. Influences of ZrO2 additions on the thermal expansion property of magnesia-alumina-chrome unfired brick, the cold properties and thermal shock resistance of fired specimens were investigated. The results show that;adding ZrO2 slows the increasing trend of linear expansion rate of the unfired brick at 1 100-1 300 ℃ and reduces the maximum value of the linear expansion coefficient; the change in dimensions, apparent porosity, cold modulus of rupture and crushing strength of the unfired bricks after firing increase with ZrO2 addition increasing;the unfired brick performs the best thermal shock resistance with 6 mass% of ZrO2.

  8. Localization of CO2 Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

    Directory of Open Access Journals (Sweden)

    Xiwang Cui

    2016-11-01

    Full Text Available Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO2 leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%.

  9. Influence of surface symmetry breaking on the magnetism, collapsing, and three-dimensional dispersion of the Co pnictides A Co2As2 (A =Ba , Sr, Ca)

    Science.gov (United States)

    Mansart, Joseph; Le Fèvre, Patrick; Bertran, François; Forget, Anne; Colson, Dorothée; Brouet, Véronique

    2016-12-01

    We use angle-resolved photoemission (ARPES) to study the three-dimensional (3D) electronic structure of Co pnictides A Co2As2 with A =Ba , Sr, Ca or a mixture of Sr and Ca. These compounds are isostructural to Fe based superconductors but have one more electron in the Co 3 d orbitals. Going from Ba to Ca, they become more and more 3D, eventually forming a "collapsed" tetragonal phase, where the distance between CoAs layers is markedly reduced. We observe with ARPES the periodicity of the electronic structure as a function of kz (i.e., perpendicularly to CoAs layers) and find that it matches in each case that expected from the distance between the planes in the bulk. However, the electronic structure is better fitted by a calculation corresponding to a slab with two CoAs layers than to the bulk structure. We attribute this to subtle modifications of the 2D electronic structure induced by the truncation of the 3D dispersion at the surface in the ARPES measurement. We further study how this affects the electronic properties. We show that, despite this distortion, the electronic structure of CaCo2As2 is essentially that expected for a collapsed phase. Electronic correlations produce a renormalization of the electronic structure by a factor 1.4, which is not affected by the transition to the collapsed state. On the other hand, a small shift of the Fermi level reduces the density of states in the eg bands and suppresses the magnetic transition expected in CaCo2As2 . Our study evidences that observing the 3D bulk periodicity is not sufficient to ensure bulk sensitivity. It further gives direct information on the role of 3D interactions, mostly governed by Co-As hybridization, among eg and t2 g orbitals. It is also useful to better understand the electronic structure of Fe superconductors and the range of validity of ARPES measurements.

  10. Determination of the Effect of Geological Reservoir Variability on Carbon Dioxide Storage Using Numerical Experiments Détermination de la variabilité des réservoirs géologiques sur le stockage du CO2 par la méthodologie des plans d’expériences

    Directory of Open Access Journals (Sweden)

    Diedro F.

    2013-06-01

    concentrations. The interaction between the sill and the range of the variogram of the initial dolomite concentration is also important. The initial calcite concentration has a slight influence only on the average porosity in the reservoir. Except for the variations of the size of the dolomite spots within the rock, small variations on the variogram parameters of the mineralogical concentration do not involve important modification of stored carbon nor of the final porosity. Dans le contexte de l’étude du stockage géologique du dioxyde de carbone dans les réservoirs sédimentaires, les simulations tentent de reproduire le plus fidèlement possible les écoulements fluides et gaz, ainsi que les réactions chimiques entre les minéraux (calcite et dolomite et le CO2 injecté [André et al. (2007 Energy Convers. Manage. 48, 1782-1797; Gunter et al. (1999 Appl. Geochem. 4, 1-11]. Cependant, les réservoirs étudiés sont généralement mal connus. Les observations sont peu nombreuses et par suite les variogrammes des propriétés pétrophysiques et minéralogiques sont approchés. L’article vise à quantifier les incertitudes sur les prévisions de stockage du CO2. Nous examinons en particulier l’effet des incertitudes sur deux paramètres opérationnels : la quantité de dioxyde de carbone stockée et la variation moyenne de la porosité. Les sources d’incertitudes retenues sont la variabilité du tirage (dispersion statistique et l’incertitude sur les paramètres du variogramme. Pour examiner la variabilité liée au tirage, les paramètres du variogramme sont fixés et plusieurs simulations sont réalisées, ce qui fournit une distribution de valeurs pour les paramètres opérationnels et permet le calcul d’une variance, apparentée à une variance de répétabilité. Dans le second cas, une analyse de sensibilité permet d’examiner l’influence des paramètres des variogrammes (palier, portée, effet de pépite sur le stockage du CO2. À cet effet, la m

  11. Water decontamination via the removal of Pb (II) using a new generation of highly energetic surface nano-material: Co(+2)Mo(+6) LDH.

    Science.gov (United States)

    Mostafa, Mohsen S; Bakr, Al-Sayed A; El Naggar, Ahmed M A; Sultan, El-Sayed A

    2016-01-01

    CoMo(CO3(2-)) layered double hydroxide of a highly energetic surface, as a new LDH consisting of divalent and hexavalent cations (M(+2)/M(+6)-LDH), was prepared by a homogeneous co-precipitation method. The structure and morphology of the prepared material was confirmed by several analytical techniques namely; X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), Fourier transform infra-red (FT-IR) spectroscopy, differential scanning calorimetry and thermal gravimetric analysis (DSC-TGA), N2 adsorption-desorption isotherm and scanning electron microscope (SEM). The highly energetic surface of the prepared LDH was demonstrated via the X-ray photoelectron spectroscopy (XPS). The surface energy is due to the formation of +4 surface charges in the brucite layer between Co(+2) and Mo(+6). The prepared LDH was applied as a novel adsorbent for the removal of Pb (II) from its aqueous solution at different experimental conditions of time, temperature and initial Pb (II) concentrations. The change of the Pb (II) concentrations; due to adsorption, was monitored by atomic absorption spectrophotometer (AAS). The maximum uptake of Pb (II) by the Co Mo LDH was (73.4 mg/g) at 298 K. The Pb (II) adsorption was found to follow Langmuir isotherm and pseudo second order model. The adsorption process was spontaneous and endothermic. The interference of other cations on the removal of the Pb (II) was studied. Na(+) and K(+) were found to increase the adsorption capacity of the Co Mo LDH toward Pb (II) while it was slightly decreased by the presence of Mn(+2) and Cu(+2). The synthesized LDH showed a great degree of recoverability (7 times) while completely conserving its parental morphology and adsorption capacity. The mechanism of the lead ions removal had exhibited more reliability through a surface adsorption by the coordination between the Mo(+6) of the brucite layers and the oxygen atoms of the nitrates counter ions.

  12. The constraint of CO2 measurements made onboard passenger aircraft on surface-atmosphere fluxes: the impact of transport model errors in vertical mixing

    Science.gov (United States)

    Verma, Shreeya; Marshall, Julia; Gerbig, Christoph; Rödenbeck, Christian; Totsche, Kai Uwe

    2017-05-01

    Inaccurate representation of atmospheric processes by transport models is a dominant source of uncertainty in inverse analyses and can lead to large discrepancies in the retrieved flux estimates. We investigate the impact of uncertainties in vertical transport as simulated by atmospheric transport models on fluxes retrieved using vertical profiles from aircraft as an observational constraint. Our numerical experiments are based on synthetic data with realistic spatial and temporal sampling of aircraft measurements. The impact of such uncertainties on the flux retrieved using the ground-based network and those retrieved using the aircraft profiles are compared. We find that the posterior flux retrieved using aircraft profiles is less susceptible to errors in boundary layer height, compared to the ground-based network. This finding highlights a benefit of utilizing atmospheric observations made onboard aircraft over surface measurements for flux estimation using inverse methods. We further use synthetic vertical profiles of CO2 in an inversion to estimate the potential of these measurements, which will be made available through the IAGOS (In-service Aircraft for a Global Observing System) project in the future, in constraining the regional carbon budget. Our results show that the regions of tropical Africa and temperate Eurasia, that are under-constrained by the existing surface-based network, will benefit the most from these measurements, with a reduction of posterior flux uncertainty of about 7 to 10 %.

  13. The optimization of essential oils supercritical CO 2 extraction from Lavandula hybrida through static-dynamic steps procedure and semi-continuous technique using response surface method

    Directory of Open Access Journals (Sweden)

    Hossein Kamali

    2015-01-01

    Full Text Available Aim: The aim of this study was to examine and evaluate crucial variables in essential oils extraction process from Lavandula hybrida through static-dynamic and semi-continuous techniques using response surface method. Materials and Methods: Essential oil components were extracted from Lavandula hybrida (Lavandin flowers using supercritical carbon dioxide via static-dynamic steps (SDS procedure, and semi-continuous (SC technique. Results: Using response surface method the optimum extraction yield (4.768% was obtained via SDS at 108.7 bar, 48.5° C , 120 min (static: 8×15, 24 min (dynamic: 8×3 min in contrast to the 4.620% extraction yield for the SC at 111.6 bar, 49.2° C , 14 min (static, 121.1 min (dynamic. Conclusion: The results indicated that a substantial reduction (81.56% solvent usage (kg CO 2 /g oil is observed in the SDS method versus the conventional SC method.

  14. MERIS Ocean Colour Data for the Estimation of Surface Water pCO2: The Case Studies of Peru and Namibia

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Badger, Merete; Sørensen, Lise Lotte

    2010-01-01

    Carbon dioxide fluxes between the ocean and atmosphere are important when trying to estimate the amount of existing atmospheric CO2. The ocean can potentially be considered as a storage or source of CO2 depending on temperature, salinity, biological activity and wind. To identify the role of a re...

  15. Effet de l'etat de la surface de l'acier au carbone 300W sur l'entartrage par la gibbsite dans le procede Bayer

    Science.gov (United States)

    Gavril, Liliana

    Une etude a ete effectuee sur l'entartrage des surfaces en acier au carbone par la gibbsite dans le procede Bayer. Trois methodes ont ete utilisees afin de determiner le mecanisme de formation du tartre: mesure de la vitesse d'entartrage, etude electrochimique et protection cathodique. Cette etude demontre que le tartre de gibbsite est un tartre de cristallisation et que l'etat physico-chimique de la surface metallique a une influence marquee sur l'entartrage. Ainsi, l'oxyde en surface a ete identifie comme un facteur determinant pour l'entartrage. Les essais electrochimiques ont montre que la couche d'oxyde formee dans les solutions Bayer est un oxyde mixte de fer et d'aluminium. Les essais de protection cathodique a courant constant valident le role determinant joue par l'oxyde sur l'entartrage, puisqu'en empechant l'oxyde de se former, l'entartrage est pratiquement elimine. Le mecanisme d'adherence du tartre a l'acier implique trois etapes, soit l'oxydation du metal, la formation de la goethite/goethite alumineuse sur l'oxyde et finalement, la germination de la gibbsite sur la goethite/goethite alumineuse.

  16. Research on the Spectral Feature and Identification of the Surface Vegetation Stressed by Stored CO2 Underground Leakage%地下储存CO2泄漏胁迫下地表植被光谱变化特征及识别研究

    Institute of Scientific and Technical Information of China (English)

    陈云浩; 蒋金豹; Michael D Steven; 宫阿都; 李一凡

    2012-01-01

    With the global climate warming, reducing greenhouse gas emissions becomes a focused problem for the world. The carbon capture and storage (CCS) techniques could mitigate CO2 into atmosphere, but there is a risk in case that the CO2 leaks from underground. The objective of this paper is to study the chlorophyll contents (SPAD value), relative water contents (RWC) and leaf spectra changing features of beetroot under CO2 leakage stress through field experiment. The result shows that the chlorophyll contents and RWC of beetroot under COz leakage stress become lower than the control beetroot', and the leaf reflectance increases in the 550 nm region and decreases in the 680nm region. A new vegetation index (R550/R680) was designed for identifying beetroot under CO2 leakage stress, and the result indicates that the vegetation index R550/R680 could identify the beetroots after CO2 leakage for 7 days. The index has strong sensitivity, stability and identification for monitoring the beetroots under CO2 stress. The result of this paper has very important meaning and application values for selecting spots of CCS project, monitoring and evaluating land-surface ecology under CO2 stress and monitoring the leakage spots by using remote sensing.%随着全球气候变暖,减少温室气体排放成为全世界所关注的问题,而碳捕捉与储存(carbon capture and storage,CCS)技术可以减少温室气体CO2排放量,但储存在地下的CO2有泄漏的风险.本工作的目的是通过野外模拟实验,研究地表植被(甜菜)在CO2轻微泄漏胁迫下其叶片叶绿素含量、水分含量及光谱变化特征,结果表明CO2泄漏胁迫的甜菜叶绿素与叶片含水量明显降低,叶片反射率在550nm减小,而在680nm增大.设计了比值指数R550/R680进行识别CO2泄漏胁迫的甜菜,发现该指数能够在胁迫发生7天后识别出胁迫的甜菜,且该指数具有较强的敏感性、稳健性及识别能力.研究结果对于未来CCS项目选址、

  17. CO2-strategier

    DEFF Research Database (Denmark)

    Jørgensen, Michael Søgaard

    2008-01-01

    I 2007 henvendte Lyngby-Taarbæk kommunens Agenda 21 koordinator sig til Videnskabsbutikken og spurgte om der var interesse for at samarbejde om CO2-strategier. Da Videnskabsbutikken DTU er en åben dør til DTU for borgerne og deres organisationer, foreslog Videnskabsbutikken DTU at Danmarks...... Naturfredningsforening’s lokalkomité for Lyngby blev en del af samarbejdet for at få borgerne i kommunen involveret i arbejdet med at udvikle strategier for reduktion af CO2. Siden sommeren 2007 har Videnskabsbutikken DTU, Lyngby-Taarbæk kommune og Danmarks Naturfredningsforening i Lyngby-Taarbæk samarbejdet om analyse...... og innovation i forhold til CO2-strategier....

  18. Porous Organic Polymers for CO2 Capture

    KAUST Repository

    Teng, Baiyang

    2013-05-01

    Carbon dioxide (CO2) has long been regarded as the major greenhouse gas, which leads to numerous negative effects on global environment. The capture and separation of CO2 by selective adsorption using porous materials proves to be an effective way to reduce the emission of CO2 to atmosphere. Porous organic polymers (POPs) are promising candidates for this application due to their readily tunable textual properties and surface functionalities. The objective of this thesis work is to develop new POPs with high CO2 adsorption capacities and CO2/N2 selectivities for post-combustion effluent (e.g. flue gas) treatment. We will also exploit the correlation between the CO2 capture performance of POPs and their textual properties/functionalities. Chapters Two focuses on the study of a group of porous phenolic-aldehyde polymers (PPAPs) synthesized by a catalyst-free method, the CO2 capture capacities of these PPAPs exceed 2.0 mmol/g at 298 K and 1 bar, while keeping CO2/N2 selectivity of more than 30 at the same time. Chapter Three reports the gas adsorption results of different hyper-cross-linked polymers (HCPs), which indicate that heterocyclo aromatic monomers can greatly enhance polymers’ CO2/N2 selectivities, and the N-H bond is proved to the active CO2 adsorption center in the N-contained (e.g. pyrrole) HCPs, which possess the highest selectivities of more than 40 at 273 K when compared with other HCPs. Chapter Four emphasizes on the chemical modification of a new designed polymer of intrinsic microporosity (PIM) with high CO2/N2 selectivity (50 at 273 K), whose experimental repeatability and chemical stability prove excellent. In Chapter Five, we demonstrate an improvement of both CO2 capture capacity and CO2/N2 selectivity by doping alkali metal ions into azo-polymers, which leads a promising method to the design of new porous organic polymers.

  19. Potential of a geostationary geoCARB mission to estimate surface emissions of CO2, CH4 and CO in a polluted urban environment: case study Shanghai

    Science.gov (United States)

    O'Brien, Denis M.; Polonsky, Igor N.; Utembe, Steven R.; Rayner, Peter J.

    2016-09-01

    This paper describes a numerical experiment to test the ability of the proposed geoCARB satellite to estimate emissions of trace gases (CO2, CH4 and CO) in the polluted urban environment of Shanghai. The meteorology over Shanghai is simulated with the Weather Research and Forecasting (WRF) model for a 9-day period in August 2010. The meteorology includes water and ice clouds. The chemistry version of WRF (WRF-Chem V3.6.1) is used to predict the chemical composition, mass density and number density of aerosol species. Spectra in the bands measured by geoCARB are calculated, including the effects of polarisation and multiple scattering of radiation by clouds, aerosols and molecules. Instrument noise is added, and column-averaged trace-gas mole fractions are estimated from the noisy spectra using an algorithm based on that for the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory-2 (OCO-2) but adapted to geoCARB. As expected, the high aerosol loadings are challenging. However, when the retrieval algorithm is provided with regionally adjusted aerosol optical properties, as might be determined from observations of dark targets within the field of regard, the accuracies of retrieved concentrations are comparable to those reported earlier for geoCARB. Statistics of the errors in the retrieved column-averaged concentrations are used to predict the reduction in uncertainty of surface emissions possible with remotely sensed data.

  20. CO2 Accounting and Risk Analysis for CO2 Sequestration at Enhanced Oil Recovery Sites.

    Science.gov (United States)

    Dai, Zhenxue; Viswanathan, Hari; Middleton, Richard; Pan, Feng; Ampomah, William; Yang, Changbing; Jia, Wei; Xiao, Ting; Lee, Si-Yong; McPherson, Brian; Balch, Robert; Grigg, Reid; White, Mark

    2016-07-19

    Using CO2 in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce sequestration costs in the absence of emissions policies that include incentives for carbon capture and storage. This study develops a multiscale statistical framework to perform CO2 accounting and risk analysis in an EOR environment at the Farnsworth Unit (FWU), Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil/gas-water flow and transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2/water injection/production rates, cumulative net CO2 storage, cumulative oil/gas productions, and CO2 breakthrough time. The median and confidence intervals are estimated for quantifying uncertainty ranges of the risk metrics. A response-surface-based economic model has been derived to calculate the CO2-EOR profitability for the FWU site with a current oil price, which suggests that approximately 31% of the 1000 realizations can be profitable. If government carbon-tax credits are available, or the oil price goes up or CO2 capture and operating expenses reduce, more realizations would be profitable. The results from this study provide valuable insights for understanding CO2 storage potential and the corresponding environmental and economic risks of commercial-scale CO2-sequestration in depleted reservoirs.

  1. CO2-neutral fuels

    Science.gov (United States)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  2. CO2-neutral fuels

    Directory of Open Access Journals (Sweden)

    Goede A. P. H.

    2015-01-01

    Full Text Available The need for storage of renewable energy (RE generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel

  3. How secure is subsurface CO2 storage? Controls on leakage in natural CO2 reservoirs

    Science.gov (United States)

    Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, Stuart

    2014-05-01

    Carbon Capture and Storage (CCS) is the only industrial scale technology available to directly reduce carbon dioxide (CO2) emissions from fossil fuelled power plants and large industrial point sources to the atmosphere. The technology includes the capture of CO2 at the source and transport to subsurface storage sites, such as depleted hydrocarbon reservoirs or saline aquifers, where it is injected and stored for long periods of time. To have an impact on the greenhouse gas emissions it is crucial that there is no or only a very low amount of leakage of CO2 from the storage sites to shallow aquifers or the surface. CO2 occurs naturally in reservoirs in the subsurface and has often been stored for millions of years without any leakage incidents. However, in some cases CO2 migrates from the reservoir to the surface. Both leaking and non-leaking natural CO2 reservoirs offer insights into the long-term behaviour of CO2 in the subsurface and on the mechanisms that lead to either leakage or retention of CO2. Here we present the results of a study on leakage mechanisms of natural CO2 reservoirs worldwide. We compiled a global dataset of 49 well described natural CO2 reservoirs of which six are leaking CO2 to the surface, 40 retain CO2 in the subsurface and for three reservoirs the evidence is inconclusive. Likelihood of leakage of CO2 from a reservoir to the surface is governed by the state of CO2 (supercritical vs. gaseous) and the pressure in the reservoir and the direct overburden. Reservoirs with gaseous CO2 is more prone to leak CO2 than reservoirs with dense supercritical CO2. If the reservoir pressure is close to or higher than the least principal stress leakage is likely to occur while reservoirs with pressures close to hydrostatic pressure and below 1200 m depth do not leak. Additionally, a positive pressure gradient from the reservoir into the caprock averts leakage of CO2 into the caprock. Leakage of CO2 occurs in all cases along a fault zone, indicating that

  4. Seasonality of biological and physical controls on surface ocean CO2 from hourly observations at the Southern Ocean Time Series site south of Australia

    Science.gov (United States)

    Shadwick, E. H.; Trull, T. W.; Tilbrook, B.; Sutton, A. J.; Schulz, E.; Sabine, C. L.

    2015-02-01

    The Subantarctic Zone (SAZ), which covers the northern half of the Southern Ocean between the Subtropical and Subantarctic Fronts, is important for air-sea CO2 exchange, ventilation of the lower thermocline, and nutrient supply for global ocean productivity. Here we present the first high-resolution autonomous observations of mixed layer CO2 partial pressure (pCO2) and hydrographic properties covering a full annual cycle in the SAZ. The amplitude of the seasonal cycle in pCO2 (˜60 μatm), from near-atmospheric equilibrium in late winter to ˜330 μatm in midsummer, results from opposing physical and biological drivers. Decomposing these contributions demonstrates that the biological control on pCO2 (up to 100 μatm), is 4 times larger than the thermal component and driven by annual net community production of 2.45 ± 1.47 mol C m-2 yr-1. After the summer biological pCO2 depletion, the return to near-atmospheric equilibrium proceeds slowly, driven in part by autumn entrainment into a deepening mixed layer and achieving full equilibration in late winter and early spring as respiration and advection complete the annual cycle. The shutdown of winter convection and associated mixed layer shoaling proceeds intermittently, appearing to frustrate the initiation of production. Horizontal processes, identified from salinity anomalies, are associated with biological pCO2 signatures but with differing impacts in winter (when they reflect far-field variations in dissolved inorganic carbon and/or biomass) and summer (when they suggest promotion of local production by the relief of silicic acid or iron limitation). These results provide clarity on SAZ seasonal carbon cycling and demonstrate that the magnitude of the seasonal pCO2 cycle is twice as large as that in the subarctic high-nutrient, low-chlorophyll waters, which can inform the selection of optimal global models in this region.

  5. CO2 capture in different carbon materials.

    Science.gov (United States)

    Jiménez, Vicente; Ramírez-Lucas, Ana; Díaz, José Antonio; Sánchez, Paula; Romero, Amaya

    2012-07-03

    In this work, the CO(2) capture capacity of different types of carbon nanofibers (platelet, fishbone, and ribbon) and amorphous carbon have been measured at 26 °C as at different pressures. The results showed that the more graphitic carbon materials adsorbed less CO(2) than more amorphous materials. Then, the aim was to improve the CO(2) adsorption capacity of the carbon materials by increasing the porosity during the chemical activation process. After chemical activation process, the amorphous carbon and platelet CNFs increased the CO(2) adsorption capacity 1.6 times, whereas fishbone and ribbon CNFs increased their CO(2) adsorption capacity 1.1 and 8.2 times, respectively. This increase of CO(2) adsorption capacity after chemical activation was due to an increase of BET surface area and pore volume in all carbon materials. Finally, the CO(2) adsorption isotherms showed that activated amorphous carbon exhibited the best CO(2) capture capacity with 72.0 wt % of CO(2) at 26 °C and 8 bar.

  6. A review on the effects of TiO2 surface point defects on CO2 photoreduction with H2O

    Directory of Open Access Journals (Sweden)

    Huilei Zhao

    2017-03-01

    Full Text Available Photocatalytic reduction of CO2 with water by photocatalysts such as TiO2 to produce solar fuels is an attractive approach to alleviate the environmental influences of greenhouse gases and in the meantime produce valuable carbon-neutral fuels. Among the materials properties that affect catalytic activity of CO2 photoreduction, the point defect on TiO2 is one of the most important but not frequently addressed and well understood in the literature. In this review, we have examined the major influences of TiO2 point defects on CO2 photoreduction with H2O, by changing the catalysts' gas adsorption capabilities, optical properties, and electronic structures. In addition, the performances of various defective TiO2 toward CO2 photoreduction are summarized and compared in terms of productivity, selectivity, and stability. We hope this review can contribute to understanding the mechanism of CO2 photoreduction on defective TiO2 and provide insights to the design of highly efficient defect-rich TiO2 to boost the CO2 utilization.

  7. Effect of CO2 Poison on the Surface Phase and the Hydrogen Isotope Permeation Capacity of Pd Membrane%CO2毒化对Pd膜表面状态与氢同位素渗透性能的影响

    Institute of Scientific and Technical Information of China (English)

    冯成; 刘颖; 连利仙; 彭丽霞; 李军; 饶永初

    2011-01-01

    The poison of Pd membrane in CO2 at different temperatures and the hydrogenization of the poisoned membrane were carried out in a silica tubular furnace and the hydrogen isotope permeation capacity was tested. The variation of Pd membrane phase and morphology was analyzed and observed by XPS and SEM. The cause and the mechanism of the variation were discussed. The results show that the molecule CO2 will dissociate to C=O, C-O and O on Pd membrane surface. The adsorptive capacity of C-O and O increases and that of C=O decreases with increasing of the temperature. PdO and micropores can be detected apparently when the poison temperature reaches 500 °C, and C-O will be adsorbed on Pd membrane surface firmly. After hydrogenization, the PdO, C-O and free O on the Pd surface vanish while C=O reappear. After the Pd membrane is poisoned by CO2, the hydrogen isotope permeation capacity of Pd membrane decreases because the atom O and C-O occupy H site and react with atom H easily.%在不同温度的CO2气氛中对Pd膜进行了毒化,将毒化后的Pd膜与氢气反应并测试其氢同位素渗透性能.采用XPS、SEM等检测了CO2在不同温度下对Pd膜毒化后的表面成分与形貌,并对比分析了吸氢前、后的Pd膜表面状态的变化,得出了CO2对Pd膜表面状态的影响规律,探讨了CO2气体的毒化机理.结果表明,CO2分子在Pd表面会解离成为C=O,C-O与O原子,随着温度升高,C=O减少,而C-O与O原子含量增加.当CO2毒化温度达到500℃时,Pd表面会生成PdO并伴有微孔出现,而C-O随温度升高能够稳定吸附于Pd表面.毒化后的试样在常温下进行吸氢反应后表面PdO消失,吸附O含量减少,多孔形貌得到改变.CO2毒化后,由于C-O与O原子在Pd表面吸附并占据了Pd膜表面的氢解离位,从而导致Pd膜透氘能力下降.

  8. CH4,CO2和H2O在非金属原子修饰石墨烯表面的吸附%CH4, CO2 and H2O Adsorption on Nonmetallic Atom-Decorated Graphene Surfaces

    Institute of Scientific and Technical Information of China (English)

    刘晓强; 田之悦; 储伟; 薛英

    2014-01-01

    煤层气(矿井瓦斯)是一种有望替代传统化石燃料,如煤、石油和天然气的非常规气体.作为可得的清洁能源,它的利用被认为是节能和经济的选择.在本工作中,非金属原子X (X=H, O, N, S, P, Si, F, Cl)修饰的石墨烯(Gr)被用来代表具有结构异性的煤表面模型.通过密度泛函理论系统地研究了煤层气组分Y (Y=CH4, CO2, H2O)在非金属原子修饰石墨烯上的吸附作用.结果表明Y在非金属原子修饰石墨烯上的吸附均为物理吸附.态密度和差分电荷密度共同表明了这种弱的相互作用.其中, H和Cl对CH4的作用较大;N、O、F、Cl对CO2的作用较强;N, Cl对H2O的影响不容忽视.总的来说,吸附能大小依次为:H2O>CO2>CH4.因此,在CH4富集的煤层里注入H2O或CO2可以与CH4形成竞争吸附,进而提高煤层气采收率.本工作提供了在分子水平下煤层气与非金属原子修饰石墨烯之间的相互作用的详情,并为煤层瓦斯的开采与分离提供了有用的信息.%As an unconventional gas, coalbed methane (CBM) is a desirable alternative energy source to conventional fossil fuels such as coal, oil, and natural gas. In this work, non-metal ic atom X (X=H, O, N, S, P, Si, F, or Cl)-decorated Gr (graphene) (X-Gr) was used to represent the surface models of coal with structural heterogeneity. Using density functional theory, the adsorption of the CBM component Y (Y=CH4, CO2, H2O) on X-Gr was systematical y investigated. The results indicate that CH4, CO2, and H2O are weakly bound to X-Gr, and the interactions between the adsorbate and the surface can be described as physisorption, which was identified through the density of states and electronic density difference analysis. Furthermore, CH4 has very large adsorption energies to H- and Cl-decorated graphene. The dopants X, such as N, O, F, and Cl, are very good adsorbents for CO2 and the influence of the dopants N and Cl cannot be ignored for the adsorption of H2O

  9. Capturing CO2 via reactions in nanopores.

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Kevin; Nenoff, Tina Maria; Criscenti, Louise Jacqueline; Tang, Z; Dong, J. H.

    2008-10-01

    This one-year exploratory LDRD aims to provide fundamental understanding of the mechanism of CO2 scrubbing platforms that will reduce green house gas emission and mitigate the effect of climate change. The project builds on the team members expertise developed in previous LDRD projects to study the capture or preferential retention of CO2 in nanoporous membranes and on metal oxide surfaces. We apply Density Functional Theory and ab initio molecular dynamics techniques to model the binding of CO2 on MgO and CaO (100) surfaces and inside water-filled, amine group functionalized silica nanopores. The results elucidate the mechanisms of CO2 trapping and clarify some confusion in the literature. Our work identifies key future calculations that will have the greatest impact on CO2 capture technologies, and provides guidance to science-based design of platforms that can separate the green house gas CO2 from power plant exhaust or even from the atmosphere. Experimentally, we modify commercial MFI zeolite membranes and find that they preferentially transmit H2 over CO2 by a factor of 34. Since zeolite has potential catalytic capability to crack hydrocarbons into CO2 and H2, this finding paves the way for zeolite membranes that can convert biofuel into H2 and separate the products all in one step.

  10. Geochemical Study of Natural CO2 Emissions in the French Massif Central: How to Predict Origin, Processes and Evolution of CO2 Leakage Étude géochimique des émissions naturelles de CO2 du Massif Central : origine et processus de migration du gaz

    Directory of Open Access Journals (Sweden)

    Battani A.

    2010-05-01

    Full Text Available This study presents an overview of some results obtained within the French ANR (National Agency of Research supported Géocarbone-Monitoring research program. The measurements were performed in Sainte-Marguerite, located in the French Massif Central. This site represents a natural laboratory for CO2/fluid/rock interactions studies, as well as CO2 migration mechanisms towards the surface. The CO2 leaking character of the studied area also allows to test and validate measurements methods and verifications for the future CO2 geological storage sites. During these surveys, we analyzed soil CO2 fluxes and concentrations. We sampled and analyzed soil gases, and gas from carbo-gaseous bubbling springs. A one-month continuous monitoring was also tested, to record the concentration of CO2 both in atmosphere and in the soil at a single point. We also developed a new methodology to collect soil gas samples for noble gas abundances and isotopic analyses, as well as carbon isotopic ratios. Our geochemical results, combined with structural geology, show that the leaking CO2 has a very deep origin, partially mantle derived. The gas rises rapidly along normal and strike-slip active faults. CO2 soil concentrations (also showing a mantle derived component and CO2 fluxes are spatially variable, and reach high values. The recorded atmospheric CO2 is not very high, despite the important CO2 degassing throughout the whole area. Cette étude présente les principaux résultats de campagnes de monitoring géochimique menées en 2006 et 2007 dans le cadre du projet Géocarbone-Monitoring, sur le site de Sainte-Marguerite, situé dans le Massif Central. Ce site constitue un « laboratoire naturel » pour l’étude des interactions CO2/fluides/roches et des mécanismes de migration du CO2 vers la surface, à l’échelle des temps géologiques. Le caractère particulièrement émissif de cet « analogue » permet également de tester et valider des méthodes de mesure et

  11. On the Vertical Gradient in CO2

    Science.gov (United States)

    Stine, A. R.; Fung, I. Y.

    2008-12-01

    Attempts to constrain surface fluxes of carbon from atmospheric measurements of carbon dioxide have primarily focused on surface boundary layer measurements, because information about surface fluxes is least diluted close to the locations where the fluxes occur. However, errors in model ventilation of air in the vertical can be misinterpreted as local surface fluxes. Satellites which measure column integrated CO2 are expected to represent a major advance in part because they observe the entire atmospheric column. Recent work has highlighted the fact that vertical gradients in carbon concentrations can give us information about where vertical mixing errors are likely to be misinterpreted as local surface fluxes, but passive tracer evidence suggests that models that capture vertical profiles on the ocean do poorly on the land (and vice versa), suggesting that the problem of correctly treating vertical mixing in inverse studies is more fundamental than picking the "best" model. We consider observations of the vertical gradient in CO2 from aircrafts and from a comparison of satellites that observe in the near infrared (which observe the column integrated CO2 field) and the thermal infrared (which observe the upper troposphere). We evaluate the feasibility of using these satellites for determining the vertical gradient in CO2. We examine how observations of the vertical gradient of CO2 allow us to differentiate the imprint of vertical mixing and the imprint in surface fluxes on the observed field of atmospheric CO2.

  12. 超临界CO2对碳纤维表面的刻蚀作用%The Etching Treatment of Carbon Fiber Surface by Supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    范大鹏; 孟令辉; 刘魁

    2013-01-01

    超临界二氧化碳(SCCO2)具有低黏度、高扩散性、高溶解度和高介电能力,利用超临界二氧化碳对PAN基碳纤维表面进行刻蚀.对超临界二氧化碳处理前后碳纤维进行分析,X射线光电子能谱(XPS)分析表明,随着处理温度的升高碳纤维表面O/C降低,这表明超临界二氧化碳对碳纤维有深度清洗的作用.X射线衍射(XRD)结果表明,随着处理温度的升高,碳纤维002晶系增加,并且石墨微晶厚度Lc和尺寸La增大.AFM观察表明,随着温度升高发现碳纤维表面沟槽变深并且碳纤维表面的粗糙度增加.此外,在200℃超临界二氧化碳处理过的碳纤维与环氧树脂的粘结性提高最高可达17.4%,经过超临界二氧化碳处理后碳纤维的层间剪切提高明显.%Supercritical carbon dioxide (SCCO2) has low viscosity, high diffusivity, high solubility and dielectricity. Based on the special properties of supercritical carbon dioxide, SCCO2 was employed to etch the surface of PAN based carbon fibers. The surface characteristics of PAN based carbon fibers were studied by atomic force microscopy (AFM), X-ray photoelectron (XPS) and X-ray diffraction analysis (XRD). It was found that the ratio of O/C on carbon fibers surface decreased due to the increase of temperatures, and it indicated that the SCCO2 had a deep cleaning effect on carbon fibers. The X-ray diffraction analysis had been used for investigating the effect of SCCO2 treatment on the structure of carbon fibers, in order to analyze the mechanics of the evolution of graphite microcrystallite structural parameters during the treatment-temperature increase. It was found that the interplanar distance of 002 crystal plane increased and the thickness (Lc) and the size (La) of graphite microcrystallite also increased with the treatment temperature. The surface of SCCO2-treated carbon fibers was observed by AFM, it was found that the grooves in the surface became deeper and the roughness increased

  13. CO2-Water-Rock Wettability: Variability, Influencing Factors, and Implications for CO2 Geostorage.

    Science.gov (United States)

    Iglauer, Stefan

    2017-05-16

    Carbon geosequestration (CGS) has been identified as a key technology to reduce anthropogenic greenhouse gas emissions and thus significantly mitigate climate change. In CGS, CO2 is captured from large point-source emitters (e.g., coal fired power stations), purified, and injected deep underground into geological formations for disposal. However, the CO2 has a lower density than the resident formation brine and thus migrates upward due to buoyancy forces. To prevent the CO2 from leaking back to the surface, four trapping mechanisms are used: (1) structural trapping (where a tight caprock acts as a seal barrier through which the CO2 cannot percolate), (2) residual trapping (where the CO2 plume is split into many micrometer-sized bubbles, which are immobilized by capillary forces in the pore network of the rock), (3) dissolution trapping (where CO2 dissolves in the formation brine and sinks deep into the reservoir due to a slight increase in brine density), and (4) mineral trapping (where the CO2 introduced into the subsurface chemically reacts with the formation brine or reservoir rock or both to form solid precipitates). The efficiency of these trapping mechanisms and the movement of CO2 through the rock are strongly influenced by the CO2-brine-rock wettability (mainly due to the small capillary-like pores in the rock which form a complex network), and it is thus of key importance to rigorously understand CO2-wettability. In this context, a substantial number of experiments have been conducted from which several conclusions can be drawn: of prime importance is the rock surface chemistry, and hydrophilic surfaces are water-wet while hydrophobic surfaces are CO2-wet. Note that CO2-wet surfaces dramatically reduce CO2 storage capacities. Furthermore, increasing pressure, salinity, or dissolved ion valency increases CO2-wettability, while the effect of temperature is not well understood. Indeed theoretical understanding of CO2-wettability and the ability to

  14. Optimization for Supercritical CO2 Extraction with Response Surface Methodology and Component Analysis of Sapindus mukorossi Oil%响应曲面法优化无患子油超临界CO2萃取工艺研究及其成分分析

    Institute of Scientific and Technical Information of China (English)

    吴燕; 肖新玉; 葛发欢

    2012-01-01

    目的:研究无患子油超临界CO2萃取工艺及其成分分析.方法:以无患子为材料,采用响应曲面法优化无患子油超临界CO2萃取工艺,并采用GC-MS对无患子油成分进行分析.结果:建立了一个能较好预测萃取结果的数学模型,并根据该方程对无患子油的超临界萃取工艺参数进行了优选.确定了无患子油超临界CO2萃取最佳工艺为:萃取压力30 MPa,萃取温度40℃,分离I压力14 MPa、温度45℃,分离Ⅱ压力6MPa、温度40℃,萃取时间60 min,得率为17.58%;并对无患子油进行了GC-MS分析,鉴定了22种成分,其中不饱和脂肪酸含量为86.59%.结论:优化后的工艺合理可行,操作简单,可用于无患子油的提取.%Objective:To study the extraction conditions of Sapindus mukorossi oil by Supercritical CO2 Extraction and identify its components. Methods: Optimized SFE-CO, Extraction by Response Surface Methodology and used GC-MS to analysis Sapindus mukorossi oil compounds. Results: Established the model of an equation for the extraction rate of Sapindus mukorossi oil by Supercritical CO2 Extraction, and the optimal parameters for the Supercritical CO2 Extraction determined by the equation were:the extraction pressure was 30 MPa, temperature was 40 ℃; The separation I pressure was 14 MPa. temperature was 45℃ ; The separation Ⅱ pressure was 6 MPa, temperature was 40℃ ; The extraction time was 60 min and the extraction rate of Sapindus mukorossi oil of 17.58%. 22 main compounds of Sapindus mukorossi oil extracted by supercritical CO2 were identified by GC-MS, unsaturated fatty acids were 86. 59%. Conclusion·This process is reliable, safe and with simple operation, and can be used for the extraction of Sapindus mukorossi oil.

  15. Effect of the Instrument Surface Heating on CO2 Flux from Open-Path Eddy Covariance System at Linze Station%仪器表面加热效应对临泽站开路涡动相关系统CO2通量的影响

    Institute of Scientific and Technical Information of China (English)

    吉喜斌; 赵文智; 康尔泗; 张智慧; 金博文; 赵丽雯

    2013-01-01

    LI-7500分析仪仪器表面加热效应对开路式涡动相关系统CO2通量观测结果影响显著,利用Burba校正方法对提高观测站CO2通量观测精度、年净生态系统碳交换量(NEE)估算、全球CO2交换量估算和气候变化模拟等具有重要意义.基于临泽站绿洲玉米农田的开路式涡动相关系统和小气候观测系统所获得的一年数据,利用Burba校正方法分别对LI-7500分析仪光路中的感热通量、大气潜热通量、CO2通量以及NEE的季节变化过程进行了修正.结果表明,LI-7500分析仪底部窗口和支杆部分热量交换是光路中感热通量校正量的主要贡献者,平均分别为6.81 W·m-2和2.68 W·m-2,其加热效应主要来源于太阳辐射和电子元件运行产生的热量;加热效应对潜热通量影响最小,平均校正量仅为0.24 W·m-2;Burba校正对CO2通量和NEE的季节变化影响显著,其平均校正量分别为19.14μg· CO2·m-2·s-1和313.21 mg·C·m-2·d-1,而且气温越低加热效应对通量的影响越显著;除生长季空气中水汽浓度显著高于非生长季而导致潜热校正量较大外,生长季其他各通量的校正量明显小于非生长季,生长季光路中感热、周围大气潜热、CO2通量和NEE日校正量分别为6.94 W·m-2、0.33 W·m-2、12.86 μg·CO2·m-2·s-1和161.58mg·C· r-2·d-1,分别是非生长季的60.4%,220.0%,50.6%和37.4%.若未进行仪器表面加热效应的Burba校正,在生长季和非生长季累计高估的绿洲玉米农田生态系统碳吸收量分别为25.85 g·C·m-2和88.47 g·C·m-2.%The instrument surface heating of LI -7500 analyzer has a significant impact on the measurement of CO2 flux from open-path eddy covariance system, and the Burba correction to CO2 flux is a most critical requirement for improving CO2 measurement, net ecosystem exchange (NEE) estimate, and global CO2 exchange and climate change modeling, etc. The sensible heat flux inside the optical path, latent

  16. Translucent CO2 ice on Mars ?

    Science.gov (United States)

    Schmidt, Frederic; Andrieu, Francois; Douté, Sylvain; Schmitt, Bernard

    2016-10-01

    The Martian climate is driven by the condensation/sublimation of CO2 representing 95% of the atmosphere. Many active surface features (such dark spot, dark flows), have been potentially linked to CO2 exchange. Understanding the surface/atmosphere interactions is a major issue, for both atmospheric but also surface science. This study aims at estimating the physical properties of the seasonal CO2 ice deposits. Are these deposits granular or compact? What is the thickness of the ice? How much impurities are included within the ice? These questions have been highly debated in the literature, in particular the presence of a translucent slab ice, the link with the H2O cycle. In particular the cold jet geyser model requires translucent CO2 ice. We use radiative transfer models to simulate spectroscopic data from the CRISM instrument and perform an inversion to estimate model's parameters though time. We then discuss the consistency of the results with other datasets.

  17. Surface modification of an Al2O3/SiO2 based ceramic treated with CO2, Nd:YAG, excimer and high power diode lasers for altered wettability characteristics

    OpenAIRE

    Lawrence, Jonathan; Li, Lin; Spencer, Julian T.

    1998-01-01

    Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of an Al2O3/SiO2 based ceramic was found to affect significant changes in the wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330 respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 1210. Such changes were identifi...

  18. Monitoring solid oxide CO2 capture sorbents in action.

    Science.gov (United States)

    Keturakis, Christopher J; Ni, Fan; Spicer, Michelle; Beaver, Michael G; Caram, Hugo S; Wachs, Israel E

    2014-12-01

    The separation, capture, and storage of CO2 , the major greenhouse gas, from industrial gas streams has received considerable attention in recent years because of concerns about environmental effects of increasing CO2 concentration in the atmosphere. An emerging area of research utilizes reversible CO2 sorbents to increase conversion and rate of forward reactions for equilibrium-controlled reactions (sorption-enhanced reactions). Little fundamental information, however, is known about the nature of the sorbent surface sites, sorbent surface-CO2 complexes, and the CO2 adsorption/desorption mechanisms. The present study directly spectroscopically monitors Na2 O/Al2 O3 sorbent-CO2 surface complexes during adsorption/desorption with simultaneous analysis of desorbed CO2 gas, allowing establishment of molecular level structure-sorption relationships between individual surface carbonate complexes and the CO2 working capacity of sorbents at different temperatures.

  19. MoS2 Nanosheets Functionalized Composite Mixed Matrix Membrane for Enhanced CO2 Capture via Surface Drop-Coating Method.

    Science.gov (United States)

    Shen, Yijia; Wang, Huixian; Zhang, Xiang; Zhang, Yatao

    2016-09-07

    Molybdenum disulfide (MoS2) is a graphene-like two-dimensional inorganic material, which has been used for the first time as an inorganic nanofiller to prepare a composite mixed matrix membrane to separate CO2 and N2. Polysulfone (PSf) was used as a support substrate and poly(dimethylsiloxane) (PDMS) was used as the gutter layer. The selective layer was prepared by mixing a CO2-philic copolymer Pebax 1657 with MoS2 nanosheets to enhance CO2 permeance. In addition, a simple drop-coating and evaporation method was developed to prepare the selective layer. Both permeability and selectivity of the MoS2-Pebax membrane have exceeded the pristine Pebax membrane. The permeability and selectivity reached to the maximum values of 64 Barrer and 93, respectively, at 0.15 wt % MoS2 nanosheets loadings. This result has been on the Robeson's upper bound line. The membrane also showed higher stability. The separation mechanism of the membrane is based on the well-known solution-diffusion mechanism. In addition, the stronger adsorption energy of MoS2 nanosheets to CO2 than N2 also provides the enhancement of gas selectivity.

  20. Activation and dissociation of CO2 on the (001), (011), and (111) surfaces of mackinawite (FeS): A dispersion-corrected DFT study

    NARCIS (Netherlands)

    Dzade, N.Y.; Roldan, Alberto; de Leeuw, N.H.

    2015-01-01

    Iron sulfide minerals, including mackinawite (FeS), are relevant in origin of life theories, due to their potential catalytic activity towards the reduction and conversion of carbon dioxide (CO2) to organic molecules, which may be applicable to the production of liquid fuels and commodity chemicals.

  1. Activation and dissociation of CO2 on the (001), (011), and (111) surfaces of mackinawite (FeS): A dispersion-corrected DFT study

    NARCIS (Netherlands)

    Dzade, N.Y.; Roldan, Alberto; de Leeuw, N.H.

    2015-01-01

    Iron sulfide minerals, including mackinawite (FeS), are relevant in origin of life theories, due to their potential catalytic activity towards the reduction and conversion of carbon dioxide (CO2) to organic molecules, which may be applicable to the production of liquid fuels and commodity chemicals.

  2. CO2 laser preionisation

    Science.gov (United States)

    Spiers, Gary D.

    1991-01-01

    The final report for work done during the reporting period of January 25, 1990 to January 24, 1991 is presented. A literature survey was conducted to identify the required parameters for effective preionization in TEA CO2 lasers and the methods and techniques for characterizing preionizers are reviewed. A numerical model of the LP-140 cavity was used to determine the cause of the transverse mode stability improvement obtained when the cavity was lengthened. The measurement of the voltage and current discharge pulses on the LP-140 were obtained and their subsequent analysis resulted in an explanation for the low efficiency of the laser. An assortment of items relating to the development of high-voltage power supplies is also provided. A program for analyzing the frequency chirp data files obtained with the HP time and frequency analyzer is included. A program to calculate the theoretical LIMP chirp is also included and a comparison between experiment and theory is made. A program for calculating the CO2 linewidth and its dependence on gas composition and pressure is presented. The program also calculates the number of axial modes under the FWHM of the line for a given resonator length. A graphical plot of the results is plotted.

  3. CO2 and CO Simulations and Their Source Signature Indicated by CO/CO2

    Science.gov (United States)

    Kawa, Randy; Huisheng, Bian

    2004-01-01

    Three years (2000-2002) atmospheric CO2 and CO fields are simulated by a Chemistry Transport Model driven by the assimilated meteorological fields from GEOS-4. The simulated CO2 and CO are evaluated by measurements from surface (CMDL), satellite (MOPITT/CO), and aircraft. The model-observation comparisons indicate reasonable agreement in both source and remote regions, and in the lower and upper troposphere. The simulation also captures the seasonality of CO2 and CO variations. The ratios of CO/CO2 are analyzed over different representative regions to identify the source signature, since the anthropogenic CO comes fiom the same combustion processes as CO2. This work enables us to improve satellite inversion estimates of CO2 sources and sinks by simultaneously using satellite CO measurement.

  4. Silvering substrates after CO2 snow cleaning

    Science.gov (United States)

    Zito, Richard R.

    2005-09-01

    There have been some questions in the astronomical community concerning the quality of silver coatings deposited on substrates that have been cleaned with carbon dioxide snow. These questions center around the possible existence of carbonate ions left behind on the substrate by CO2. Such carbonate ions could react with deposited silver to produce insoluble silver carbonate, thereby reducing film adhesion and reflectivity. Carbonate ions could be produced from CO2 via the following mechanism. First, during CO2 snow cleaning, a small amount of moisture can condense on a surface. This is especially true if the jet of CO2 is allowed to dwell on one spot. CO2 gas can dissolve in this moisture, producing carbonic acid, which can undergo two acid dissociations to form carbonate ions. In reality, it is highly unlikely that charged carbonate ions will remain stable on a substrate for very long. As condensed water evaporates, Le Chatelier's principle will shift the equilibrium of the chain of reactions that produced carbonate back to CO2 gas. Furthermore, the hydration of CO2 reaction of CO2 with H20) is an extremely slow process, and the total dehydrogenation of carbonic acid is not favored. Living tissues that must carry out the equilibration of carbonic acid and CO2 use the enzyme carbonic anhydrase to speed up the reaction by a factor of one million. But no such enzymatic action is present on a clean mirror substrate. In short, the worst case analysis presented below shows that the ratio of silver atoms to carbonate radicals must be at least 500 million to one. The results of chemical tests presented here support this view. Furthermore, film lift-off tests, also presented in this report, show that silver film adhesion to fused silica substrates is actually enhanced by CO2 snow cleaning.

  5. The Abundance of Atmospheric CO2 in Ocean Exoplanets: a Novel CO2 Deposition Mechanism

    Science.gov (United States)

    Levi, A.; Sasselov, D.; Podolak, M.

    2017-03-01

    We consider super-Earth sized planets which have a water mass fraction large enough to form an external mantle composed of high-pressure water-ice polymorphs and also lack a substantial H/He atmosphere. We consider such planets in their habitable zone, so that their outermost condensed mantle is a global, deep, liquid ocean. For these ocean planets, we investigate potential internal reservoirs of CO2, the amount of CO2 dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO2. We find that, in a steady state, the abundance of CO2 in the atmosphere has two possible states. When wind-driven circulation is the dominant CO2 exchange mechanism, an atmosphere of tens of bars of CO2 results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO2 deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO2 is established. The exact value depends on the subpolar surface temperature. Our results suggest the possibility of a negative feedback mechanism, unique to water planets, where a reduction in the subpolar temperature drives more CO2 into the atmosphere to increase the greenhouse effect.

  6. Fingerprinting captured CO2 using natural tracers: Determining CO2 fate and proving ownership

    Science.gov (United States)

    Flude, Stephanie; Gilfillan, Stuart; Johnston, Gareth; Stuart, Finlay; Haszeldine, Stuart

    2016-04-01

    In the long term, captured CO2 will most likely be stored in large saline formations and it is highly likely that CO2 from multiple operators will be injected into a single saline formation. Understanding CO2 behavior within the reservoir is vital for making operational decisions and often uses geochemical techniques. Furthermore, in the event of a CO2 leak, being able to identify the owner of the CO2 is of vital importance in terms of liability and remediation. Addition of geochemical tracers to the CO2 stream is an effective way of tagging the CO2 from different power stations, but may become prohibitively expensive at large scale storage sites. Here we present results from a project assessing whether the natural isotopic composition (C, O and noble gas isotopes) of captured CO2 is sufficient to distinguish CO2 captured using different technologies and from different fuel sources, from likely baseline conditions. Results include analytical measurements of CO2 captured from a number of different CO2 capture plants and a comprehensive literature review of the known and hypothetical isotopic compositions of captured CO2 and baseline conditions. Key findings from the literature review suggest that the carbon isotope composition will be most strongly controlled by that of the feedstock, but significant fractionation is possible during the capture process; oxygen isotopes are likely to be controlled by the isotopic composition of any water used in either the industrial process or the capture technology; and noble gases concentrations will likely be controlled by the capture technique employed. Preliminary analytical results are in agreement with these predictions. Comparison with summaries of likely storage reservoir baseline and shallow or surface leakage reservoir baseline data suggests that C-isotopes are likely to be valuable tracers of CO2 in the storage reservoir, while noble gases may be particularly valuable as tracers of potential leakage.

  7. 响应面法优化超临界CO2萃取丁香酚的工艺研究%Optimization of supercritical CO2 extraction of eugenol from clove (Eugenia caryophyllata Thunb) bud by response surface methodology

    Institute of Scientific and Technical Information of China (English)

    谢莹莹; 王志祥; 史益强; 丁朝中

    2013-01-01

    Objective To optimize the supercritical CO2 extraction process of cugcnol from colve(Eugenia caryophyllata Thunb). Method On the basis of single factors, using extraction rate as reference, extraction conditions of cugcnol from clove (Eugenia car yo phyllala Thunb) bud with supercritical CO2 extraction was optimized with response surface analysis. Results The optimum extraction conditions were as follows: power 25 Mpa, temperature 55 ℃ , time 1 h, volume fraction of alcohol 90%, and flow of modifier 0.04 mL · min-1 ,particle size 100 mesh. Under these conditions cugenol extraction rate could reach to 17. 41 %. Conclusion The optimized process conditions arc stable and practicable in manufacture.%目的 优选丁香中丁香酚的超临界CO2萃取工艺.方法 以丁香酚得率为考察指标,在单因素实验的基础上,采用响应面法对超临界CO2萃取丁香酚的工艺条件进行优化.结果 得到优选萃取条件为:萃取压力25 MPa,萃取温度55 ℃,萃取时间1 h,夹带剂体积分数90%乙醇,夹带剂流量0.04 mL·min-1,原料粒径100目,在此条件下丁香酚得率可达到17.41%.结论 优选的萃取工艺稳定、可行.

  8. An analysis of methanol synthesis from CO and CO 2 on Cu and Pd surfaces by the bond-order-conservation-Morse-potential approach

    Science.gov (United States)

    Shustorovich, Evgeny; Bell, Alexis T.

    1991-08-01

    The mechanisms of methanol synthesis from CO and CO 2 on Cu(111) and Pd(111) have been analyzed using the BOC-MP (bond-order-conservation-Morse-potential) approach. The analysis was based on calculations of the heats of chemisorption, Q, for all adsorbed species and the activation barriers, Δ E∗, for all elementary reactions believed to be involved in the synthesis of methanol from CO and CO 2. The relevant experimental values of Q and Δ E∗, although scarce, agree well with the BOC-MP estimates. The formyl and formate routes to methanol were compared. On Cu(111), the activation barrier for hydrogenation of CO s to HCO s is found to be much larger than that for the desorption of CO s, which makes formyl formation non-competitive. By contrast, on Pd(111) the two barriers are calculated to be practically equal, making it very likely that formyl groups are formed. In the presence of OH s groups, formate formation via the reaction CO s + OH s → HCOO s is found to have a low activation barrier, particularly on Cu(111), where the formate route to methanol is preferred. The rate determining step in this case is projected to be the hydrogenolysis of formate groups to form formaldehyde and atomic oxygen. On Cu(111) the formate route also appears to be efficient for the hydrogenation of CO 2 to methanol, since the activation barrier for H s + CO 2,s → HCOO s is calculated to be smaller than that for desorption of CO 2,s. The reverse is true for Pd(111), which makes the formate route to methanol energetically unfavorable in this case. The mechanism of the WGS reaction has also been considered. It appears that the reaction does not proceed via the formate intermediate, and the rate-determining step for this reaction is projected to be the dissociation of water. On Cu(111), the reverse WGS reaction is found to be competitive with methanol formation. The BOC-MP projections are generally consistent with the observed features of hydrogenation of CO and CO 2 on Cu and Pd

  9. Multi-technique monitoring of CO2 leakage from an engineered CO2 leakage experiment

    Science.gov (United States)

    Zhou, X.; Apple, M. E.; Dobeck, L.; Cunningham, A. B.; Spangler, L.

    2012-12-01

    Monitoring of canopy and soil geophysical and geochemical properties in vadose zone by multiple techniques were carried out from 1999 to 2012 using an engineered CO2 release to simulate the CO2 leakage from CO2 storage at an agricultural plot at Bozeman, MT. The CO2 release was based on a horizontally-drilled well of 100 m at a depth of about 2.0-2.3m (Fig.1). Techniques utilized include hyperspectral and infrared radiation of various vegetations, electric conductivity in soil, magnetic field at the ground surface, and soil gas composition and dynamics using various gas sensors and soil moisture sensors. Measurements were made at several sites along a transect perpendicular to the releasing well, along which the soil CO2 concentration attenuated from high to normal condition at control site. The response of the canopy hyperspectral reflectance, infrared radiation, soil geophysical properties such as soil electric conductivity, top soil magnetic susceptibility and magnetic field, soil gas composition such as CO2 and O2 concentration to CO2 release at different rates were quantified and will be shown at this presentation. Fig.2 shows some examples of the results. The different responses at the impact and control sites are used to assess the effectiveness for CO2 surface and near-surface detection when a possible CO2 leakage occurs.ig.1. A schematic showing the injection and release of CO2 at an agricultral plot in Bozeman, MT. ig.2. Some examples of results showing the response of vegetation, hyperspectral reflectance, soil electric conductivity, soil O2 concentration to the release of CO2.

  10. On Leakage from Geologic Storage Reservoirs of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, Karsten

    2006-02-14

    Large amounts of CO2 would need to be injected underground to achieve a significant reduction of atmospheric emissions. The large areal extent expected for CO2 plumes makes it likely that caprock imperfections will be encountered, such as fault zones or fractures, which may allow some CO2 to escape from the primary storage reservoir. Leakage of CO2 could also occur along wellbores. Concerns with escape of CO2 from a primary geologic storage reservoir include (1) acidification of groundwater resources, (2) asphyxiation hazard when leaking CO2 is discharged at the land surface, (3) increase in atmospheric concentrations of CO2, and (4) damage from a high-energy, eruptive discharge (if such discharge is physically possible). In order to gain public acceptance for geologic storage as a viable technology for reducing atmospheric emissions of CO2, it is necessary to address these issues and demonstrate that CO2 can be injected and stored safely in geologic formations.

  11. Glacial CO2 Cycles: A Composite Scenario

    Science.gov (United States)

    Broecker, W. S.

    2015-12-01

    There are three main contributors to the glacial drawdown of atmospheric CO2 content: starvation of the supply of carbon to the ocean-atmosphere reservoir, excess CO2 storage in the deep sea, and surface-ocean cooling. In this talk, I explore a scenario in which all three play significant roles. Key to this scenario is the assumption that deep ocean storage is related to the extent of nutrient stratification of the deep Atlantic. The stronger this stratification, the larger the storage of respiration CO2. Further, it is my contention that the link between Milankovitch insolation cycles and climate is reorganizations of the ocean's thermohaline circulation leading to changes in the deep ocean's CO2 storage. If this is the case, the deep Atlantic d13C record kept in benthic foraminifera shells tells us that deep ocean CO2 storage follows Northern Hemisphere summer insolation cycles and thus lacks the downward ramp so prominent in the records of sea level, benthic 18O and CO2. Rather, the ramp is created by the damping of planetary CO2 emissions during glacial time intervals. As it is premature to present a specific scenario, I provide an example as to how these three contributors might be combined. As their magnitudes and shapes remain largely unconstrained, the intent of this exercise is to provoke creative thinking.

  12. High energy asymmetric supercapacitor with 1D@2D structured NiCo2O4@Co3O4 and jackfruit derived high surface area porous carbon

    Science.gov (United States)

    Sennu, Palanichamy; Aravindan, Vanchiappan; Lee, Yun-Sung

    2016-02-01

    We report the fabrication of high energy asymmetric supercapacitor (ASC) using pseudocapacitive 3D microstructured composite NiCo2O4@Co3O4 and double layer forming activated carbon (AC). The pseudo capacitive electrode is synthesized via a facile two step hydrothermal process and AC is obtained from the bio-waste, Jackfruit (JF) peel by chemical activation. Extensive powder characterization and optimization has been conducted for both electrodes, especially in electrochemical aspect. The ASC is fabricated using JF derived AC as anode and NiCo2O4@Co3O4 cathode in aqueous media. Prior to the ASC assembly, the mass loading between the electrodes are adjusted based on the single electrode performance of both components vs. Ag/AgCl. The ASC is capable of delivering a maximum energy density of 42.5 Wh kg-1 at power density of 80 W kg-1. In addition, the ASC rendered excellent cycleability, for example, the cell retains ∼97% of initial capacitance after 7000 cycles. The outstanding performance of the ASC is originated from the well-developed building blocks of porous electrodes. An impedance study is also conducted to corroborate the excellent performance of NiCo2O4@Co3O4vs. JF derived AC based ASC.

  13. Effects of Doubled CO2 on Tropical Sea-Surface Temperature (SSTs) for Onset of Deep Convection and Maximum SST-GCM Simulations Based Inferences

    Science.gov (United States)

    Sud, Y. C.; Walker, G. K.; Zhou, Y. P.; Schmidt, Gavin A.; Lau, K. M.; Cahalan, R. F.

    2008-01-01

    A primary concern of CO2-induced warming is the associated rise of tropical (10S-10N) seasurface temperatures (SSTs). GISS Model-E was used to produce two sets of simulations-one with the present-day and one with doubled CO2 in the atmosphere. The intrinsic usefulness of model guidance in the tropics was confirmed when the model simulated realistic convective coupling between SSTs and atmospheric soundings and that the simulated-data correlations between SSTs and 300 hPa moiststatic energies were found to be similar to the observed. Model predicted SST limits: (i) one for the onset of deep convection and (ii) one for maximum SST, increased in the doubled C02 case. Changes in cloud heights, cloud frequencies, and cloud mass-fractions showed that convective-cloud changes increased the SSTs, while warmer mixed-layer of the doubled CO2 contained approximately 10% more water vapor; clearly that would be conducive to more intense storms and hurricanes.

  14. Measuring H, O, li, B, and BE on Planetary Surfaces: Calibration of Laser-Induced Breakdown Spectroscopy (libs) Data Under Air, Vacuum, and CO2

    Science.gov (United States)

    Dyar, M. D.; Nelms, M.; Breves, E. A.

    2012-12-01

    other light elements are directly measured are nearly nonexistent in the 1-2 g quantities needed for LIBS analyses. For this study, we have obtained two sample suites that provide calibrations needed for accurate analyses of H, O, B, Be, and Li in geological samples. The first suite of 11 samples was analyzed for oxygen by fast neutron activation analysis. The second suite includes 11 gem-quality minerals representing the major rock-forming species for B, Li, and Be-rich parageneses. Light elements were directly analyzed using a combination of EMPA, XRF, ion microprobe, uranium extraction, proton-induced gamma-ray emission (PIGE), and prompt gamma-ray neutron activation analysis (PGNAA). LIBS spectra were acquired at Mount Holyoke College under air, vacuum, and CO2 to simulate terrestrial, lunar, and martian environments. Spectra were then used to develop three separate calibration models (one for each environment), enabling LIBS characterization of light elements using multivariate analyses. Results show that when direct analyses of H, O, Li, B, and Be are used rather than LOI results, inferred, or indirectly calculated values, optimal root mean squared errors of prediction result. We are actively adding samples to these calibration suites, and we expect that prediction errors (accuracies) of <1wt% for these elements are possible.

  15. Global CO2 fluxes estimated from GOSAT retrievals of total column CO2

    Directory of Open Access Journals (Sweden)

    S. Basu

    2013-09-01

    Full Text Available We present one of the first estimates of the global distribution of CO2 surface fluxes using total column CO2 measurements retrieved by the SRON-KIT RemoTeC algorithm from the Greenhouse gases Observing SATellite (GOSAT. We derive optimized fluxes from June 2009 to December 2010. We estimate fluxes from surface CO2 measurements to use as baselines for comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we can reproduce the observed CO2 time series at surface and TCCON sites in the tropics and the northern extra-tropics. In contrast, in the southern extra-tropics GOSAT XCO2 leads to enhanced seasonal cycle amplitudes compared to independent measurements, and we identify it as the result of a land–sea bias in our GOSAT XCO2 retrievals. A bias correction in the form of a global offset between GOSAT land and sea pixels in a joint inversion of satellite and surface measurements of CO2 yields plausible global flux estimates which are more tightly constrained than in an inversion using surface CO2 data alone. We show that assimilating the bias-corrected GOSAT data on top of surface CO2 data (a reduces the estimated global land sink of CO2, and (b shifts the terrestrial net uptake of carbon from the tropics to the extra-tropics. It is concluded that while GOSAT total column CO2 provide useful constraints for source–sink inversions, small spatiotemporal biases – beyond what can be detected using current validation techniques – have serious consequences for optimized fluxes, even aggregated over continental scales.

  16. Global CO2 fluxes estimated from GOSAT retrievals of total column CO2

    Directory of Open Access Journals (Sweden)

    M. Torn

    2013-02-01

    Full Text Available We present one of the first estimates of the global distribution of CO2 surface fluxes using total column CO2 measurements retrieved from the Greenhouse gases Observing SATellite (GOSAT. We derive optimized fluxes from June 2009 to December 2010. We estimate fluxes from surface CO2 measurements to use as baselines for comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we can reproduce the observed CO2 time series at surface and TCCON sites in the tropics and the northern extra-tropics. In contrast, in the southern extra-tropics GOSAT XCO2 leads to enhanced seasonal cycle amplitudes compared to independent measurements, and we identify it as the result of a land-sea bias in our GOSAT XCO2 retrievals. A bias correction in the form of a global offset between GOSAT land and sea pixels in a joint inversion of satellite and surface measurements of CO2 yields plausible global flux estimates which are more tightly constrained than in an inversion using surface CO2 data alone. We show that assimilating the bias-corrected GOSAT data on top of surface CO2 data (a reduces the estimated global land sink of CO2, and (b shifts the terrestrial net uptake of carbon from the tropics to the extra-tropics. It is concluded that while GOSAT total column CO2 provide useful constraints for source-sink inversions, small spatiotemporal biases – beyond what can be detected using current validation techniques – have serious consequences for optimized fluxes, even aggregated over continental scales.

  17. Sur les Automorphismes de Groupes Libres et de Groupes de Surface

    CERN Document Server

    Paulin, Frédéric

    2011-01-01

    The special linear groups, the mapping class groups of surfaces, the outer autormorphism groups of free groups appear in numerous domains. Their analogies, developped in particular in K. Vogtmann's work, have been written about a lot. In this report, we concentrate on the contractible spaces on which these groups act in an analogous way, on the common properties of their subgroups, and on the similar (or conjecturally similar) properties of their asymptotic geometry.

  18. Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO2 budget in South America

    Science.gov (United States)

    Moreira, D. S.; Freitas, S. R.; Bonatti, J. P.; Mercado, L. M.; Rosário, N. M. É.; Longo, K. M.; Miller, J. B.; Gloor, M.; Gatti, L. V.

    2013-01-01

    This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation) and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March) and dry (September) seasons of 2010. The statistics used to perform the evaluation included bias (BIAS) and root mean squared error (RMSE). The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.

  19. Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0: applications to numerical weather forecasting and the CO2 budget in South America

    Directory of Open Access Journals (Sweden)

    D. S. Moreira

    2013-01-01

    Full Text Available This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March and dry (September seasons of 2010. The statistics used to perform the evaluation included bias (BIAS and root mean squared error (RMSE. The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3 surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.

  20. The Li–CO2 battery: a novel method for CO2 capture and utilization

    KAUST Repository

    Xu, Shaomao

    2013-01-01

    We report a novel primary Li-CO2 battery that consumes pure CO2 gas as its cathode. The battery exhibits a high discharge capacity of around 2500 mA h g-1 at moderate temperatures. At 100 °C the discharge capacity is close to 1000% higher than that at 40 °C, and the temperature dependence is significantly weaker for higher surface area carbon cathodes. Ex-situ FTIR and XRD analyses convincingly show that lithium carbonate (Li2CO3) is the main component of the discharge product. The feasibility of similar primary metal-CO2 batteries based on earth abundant metal anodes, such as Al and Mg, is demonstrated. The metal-CO2 battery platform provides a novel approach for simultaneous capturing of CO2 emissions and producing electrical energy. © 2013 The Royal Society of Chemistry.

  1. The Abundance of Atmospheric CO2 in Ocean Exoplanets: A Novel CO2 Deposition Mechanism

    CERN Document Server

    Levi, Amit; Podolak, Morris

    2016-01-01

    We consider super-Earth sized planets which have a water mass fraction that is large enough to form an external mantle composed of high pressure water ice polymorphs and that lack a substantial H/He atmosphere. We consider such planets in their habitable zone so that their outermost condensed mantle is a global deep liquid ocean. For these ocean planets we investigate potential internal reservoirs of CO2; the amount of CO2 dissolved in the ocean for the various saturation conditions encountered, and the ocean-atmosphere exchange flux of CO2. We find that in steady state the abundance of CO2 in the atmosphere has two possible states. When the wind-driven circulation is the dominant CO2 exchange mechanism, an atmosphere of tens of bars of CO2 results, where the exact value depends on the subtropical ocean surface temperature and the deep ocean temperature. When sea-ice formation, acting on these planets as a CO2 deposition mechanism, is the dominant exchange mechanism, an atmosphere of a few bars of CO2 is esta...

  2. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Directory of Open Access Journals (Sweden)

    L. Ammoura

    2012-10-01

    Full Text Available Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI and urban-rural contrasts. Boundary layer heights (BLH at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical

  3. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2012-10-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI) and urban-rural contrasts. Boundary layer heights (BLH) at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL) growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical transport, or in

  4. India Co2 Emissions

    Science.gov (United States)

    Sharan, S.; Diffenbaugh, N. S.

    2010-12-01

    created a balance in between the “developed” and developing countries. If India was producing the same amounts of emissions per capita as the it would have a total of 20 billion metric tons of CO2 emissions annually.

  5. 响应面设计优化超临界CO2法制备盐酸小檗碱脂质体的处方工艺%Response surface methodology optimization of formulation using supercritical CO2 to prepare berberine liposome

    Institute of Scientific and Technical Information of China (English)

    张志丽; 张少华; 张志云; 郭永学; 周丽莉

    2012-01-01

    目的 采用中心复合设计实验优化超临界CO2法制备盐酸小檗碱脂质体的处方工艺.方法 考察药脂质量比和磷脂质量浓度对盐酸小檗碱脂质体包封率的影响,采用中心复合设计实验对超临界制备盐酸小檗碱处方工艺进行优化,并利用响应曲面法进行优化分析.结果 最优的工艺条件为:药脂质量比为13.2∶60,磷脂质量浓度为30 g·L-1,理论包封率为73.30%,载药量为15.98%.在此条件下的实际包封率为(72.15±1.9)%,载药量为15.74%,接近理论预测值.结论 作者研究的超临界CO2法制备盐酸小檗碱脂质体,实现了包封率与载药量的最佳组合,且工艺简单,适合工业生产.%Objective To develop a procedure to prepare and characterize berberine liposome using supercritical CO2. Methods The investigation of drug to phospholipid ratio(m- m) and the concentration of soya phos-phatidyl choline(SPC)on berberine hydrochloride liposome entrapment efficiency influence were studied to get the range of critical factors and then optimized by central composite design experiment using response surface methodology (RSM) to get the maximum entrapment efficiency and drug loading. Results The optimal formulation was as follow;the ratio of the amount of drug to phospholipid was 13. 25:60,and the concentration of soya phosphatidyl choline ( SPC) was 30 g·L-1,15. 74% berberine was loaded on liposomes and the entrapment efficiency reached 72. 15%. Conclusions The preparation of berberine hydrochloride liposome by using supercritical CO2 technology is proved to be the optimal combination both for entrapment efficiency and drug loading. The procedure is simple and suitable for the industrial production.

  6. CO2 as a refrigerant

    CERN Document Server

    2014-01-01

    A first edition, the IIR guide “CO2 as a Refrigerant” highlights the application of carbon dioxide in supermarkets, industrial freezers, refrigerated transport, and cold stores as well as ice rinks, chillers, air conditioning systems, data centers and heat pumps. This guide is for design and development engineers needing instruction and inspiration as well as non-technical experts seeking background information on a specific topic. Written by Dr A.B. Pearson, a well-known expert in the field who has considerable experience in the use of CO2 as a refrigerant. Main topics: Thermophysical properties of CO2 – Exposure to CO2, safety precautions – CO2 Plant Design – CO2 applications – Future prospects – Standards and regulations – Bibliography.

  7. Precursory volcanic CO2 signals from space

    Science.gov (United States)

    Schwandner, Florian M.; Carn, Simon A.; Kataoka, Fumie; Kuze, Akihiko; Shiomi, Kei; Goto, Naoki

    2016-04-01

    Identification of earliest signals heralding volcanic unrest benefits from the unambiguous detection of precursors that reflect deviation of magmatic systems from metastable background activity. Ascent and emplacement of new basaltic magma at depth may precede eruptions by weeks to months. Transient localized carbon dioxide (CO2) emissions stemming from exsolution from depressurized magma are expected, and have been observed weeks to months ahead of magmatic surface activity. Detecting such CO2 precursors by continuous ground-based monitoring operations is unfortunately not a widely implemented method yet, save a handful of volcanoes. Detecting CO2 emissions from space offers obvious advantages - however it is technologically challenging, not the least due to the increasing atmospheric burden of CO2, against which a surface emission signal is hard to discern. In a multi-year project, we have investigated the feasibility of space-borne detection of pre-eruptive volcanic CO2 passive degassing signals using observations from the Greenhouse Gas Observing SATellite (GOSAT). Since 2010, we have observed over 40 active volcanoes from space using GOSAT's special target mode. Over 72% of targets experienced at least one eruption over that time period, demonstrating the potential utility of space-borne CO2 observations in non-imaging target-mode (point source monitoring mode). While many eruption precursors don't produce large enough CO2 signals to exceed space-borne detection thresholds of current satellite sensors, some of our observations have nevertheless already shown significant positive anomalies preceding eruptions at basaltic volcanoes. In 2014, NASA launched its first satellite dedicated to atmospheric CO2 observation, the Orbiting Carbon Observatory (OCO-2). Its observation strategy differs from the single-shot GOSAT instrument. At the expense of GOSAT's fast time series capability (3-day repeat cycle, vs. 16 for OCO-2), its 8-footprint continuous swath can slice

  8. Warming the early Earth - CO2 reconsidered

    CERN Document Server

    Von Paris, P; Grenfell, L; Patzer, B; Hedelt, P; Stracke, B; Trautmann, T; Schreier, F

    2008-01-01

    Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called "faint young Sun problem" have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies. For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 ...

  9. Étude théorique de divers processus atomiques de croissance sur les surfaces métalliques

    OpenAIRE

    1996-01-01

    L'intérêt technologique des matériaux multicouches et la nécessité de comprendre, et si possible de maîtriser, les processus atomiques qui se produisent lors de leur élaboration a suscité depuis quelques années un regain d'activité sur les mécanismes élémentaires intervenant dans la croissance cristalline. Ces processus atomiques sont nombreux. Pour former une nouvelle couche à faible sursaturation, les atomes venant de la vapeur doivent d'abord se condenser sur le substrat, puis diffusent su...

  10. Planification de trajectoires pour placement automatise de fibres sur surfaces de geometries complexes

    Science.gov (United States)

    Hely, Clement

    During the past 50 years, the use of composite materials drastically increase, mainly thanks to the interest of aeronautical industries for these strong and lightweight materials. To improve the productivity of composite materials manufacturing some of the largest aeronautics companies began to develop automated processes such as Automated Fibre Placement (AFP). The AFP workcells currently used by the industry were mainly developed for production of large, nearly flat, plates with low curvatures such as aircraft fuselages. However, the fields of aeronautics and sport goods production begin nowadays to show an interest for manufacturing of smaller and more complex parts. The aim of the project in which this research takes place is to design a new AFP workcell and to develop new techniques allowing production of parts with small size and complex geometry. The work presented in this thesis focuses on the path planning on multi-axial revolution surfaces, e.g. Y-shaped tubes of constant circular cross section. Several path planning algorithms will be presented aiming at the exhaustive coverage of a mandrel with pre-impregnated (prepreg) composite tape. The methodology used in two of these algorithms is to individually cover each branch of the Y-shaped part with paths deriving from a helix. In the first one, the helix will be cut at the boundary between a branch and the junction region (algorithm HD) while in the second (algorithm HA) the pseudo-helix path can be adjusted to follow this boundary. These two methods were shown to have some drawbacks compromising their practical use and possibly leading to parts with diminished mechanical properties. To avoid these drawbacks, two others algorithms were developed with a new methodology. With them, the aim is to cover two branches of the Y-shape with a continuous course (i.e. without cut). The first one uses a well known strategy which defines plies with a constant fibre orientation. Parallel paths are then computed to

  11. Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts

    Science.gov (United States)

    Brioude, Jerome; Angevine, Wayne; Ahmadov, Ravan; Kim, Si Wan; Evan, Stephanie; McKeen, Stuart; Hsie, Eirh Yu; Frost, Greg; Neuman, Andy; Pollack, Ilana; Peischl, Jeff; Ryerson, Tom; Holloway, John; Brown, Steeve; Nowak, John; Roberts, Jim; Wofsy, Steeve; Santoni, Greg; Trainer, Michael

    2013-04-01

    We present top-down estimates of anthropogenic CO, NOx and CO2 surface fluxes at mesoscale using a Lagrangian model in combination with three different WRF model configurations, driven by data from aircraft flights during the CALNEX campaign in southern California in May-June 2010. The US EPA National Emission Inventory 2005 (NEI 2005) was the prior in the CO and NOx inversion calculations. The flux ratio inversion method, based on linear relationships between chemical species, was used to calculate the CO2 inventory without prior knowledge of CO2 surface fluxes. The inversion was applied to each flight to estimate the variability of single-flight-based flux estimates. In Los Angeles (LA) County, the uncertainties on CO and NOx fluxes were 10% and 15%, respectively. Compared with NEI 2005, the CO posterior emissions were lower by 43% ± 6% in LA County and by 37% ± 10% in the South Coast Air Basin (SoCAB). NOx posterior emissions were lower by 32% ± 10% in LA County and by 27% ± 15% in the SoCAB. NOx posterior emissions were 40% lower on weekends relative to weekdays. The CO2 posterior estimates were 183 ± 18 Tg yr-1 in SoCAB. A flight during ITCT in 2002 was used to estimate emissions in the LA Basin in 2002. From 2002 to 2010, the CO and NOx posterior emissions decreased by 41% and 37%, respectively, in agreement with previous studies. Over the same time period, CO2 emissions increased by 10% ± 14% in LA County but decreased by 4% ± 10% in the SoCAB, a statistically insignificant change. Overall, the posterior estimates were in good agreement with the California Air Resources Board (CARB) inventory, with differences of 15% or less. However, the posterior spatial distribution in the basin was significantly different from CARB for NOx emissions. WRF-Chem mesoscale chemical-transport model simulations allowed an evaluation of differences in chemistry using different inventory assumptions, including NEI 2005, CARB 2010 and the posterior inventories derived in

  12. Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts

    Directory of Open Access Journals (Sweden)

    S. C. Wofsy

    2012-12-01

    Full Text Available We present top-down estimates of anthropogenic CO, NOx and CO2 surface fluxes at mesoscale using a Lagrangian model in combination with three different WRF model configurations, driven by data from aircraft flights during the CALNEX campaign in southern California in May–June 2010. The US EPA National Emission Inventory 2005 (NEI 2005 was the prior in the CO and NOx inversion calculations. The flux ratio inversion method, based on linear relationships between chemical species, was used to calculate the CO2 inventory without prior knowledge of CO2 surface fluxes. The inversion was applied to each flight to estimate the variability of single-flight-based flux estimates. In Los Angeles (LA County, the uncertainties on CO and NOx fluxes were 10% and 15%, respectively. Compared with NEI 2005, the CO posterior emissions were lower by 43% ± 6% in LA County and by 37% ± 10% in the South Coast Air Basin (SoCAB. NOx posterior emissions were lower by 32% ± 10% in LA County and by 27% ± 15% in the SoCAB. NOx posterior emissions were 40% lower on weekends relative to weekdays. The CO2 posterior estimates were 183 ± 18 Tg yr−1 in SoCAB. A flight during ITCT in 2002 was used to estimate emissions in the LA Basin in 2002. From 2002 to 2010, the CO and NOx posterior emissions decreased by 41% and 37%, respectively, in agreement with previous studies. Over the same time period, CO2 emissions increased by 10% ± 14% in LA County but decreased by 4% ± 10% in the SoCAB, a statistically insignificant change. Overall, the posterior estimates were in good agreement with the California Air Resources Board (CARB inventory, with differences of 15% or less. However, the posterior spatial distribution in the basin was significantly different from CARB for NOx emissions. WRF-Chem mesoscale chemical-transport model simulations allowed an evaluation of differences in chemistry using different inventory assumptions, including NEI 2005, CARB 2010 and the posterior

  13. Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2013-04-01

    Full Text Available We present top-down estimates of anthropogenic CO, NOx and CO2 surface fluxes at mesoscale using a Lagrangian model in combination with three different WRF model configurations, driven by data from aircraft flights during the CALNEX campaign in southern California in May–June 2010. The US EPA National Emission Inventory 2005 (NEI 2005 was the prior in the CO and NOx inversion calculations. The flux ratio inversion method, based on linear relationships between chemical species, was used to calculate the CO2 inventory without prior knowledge of CO2 surface fluxes. The inversion was applied to each flight to estimate the variability of single-flight-based flux estimates. In Los Angeles (LA County, the uncertainties on CO and NOx fluxes were 10% and 15%, respectively. Compared with NEI 2005, the CO posterior emissions were lower by 43% in LA County and by 37% in the South Coast Air Basin (SoCAB. NOx posterior emissions were lower by 32% in LA County and by 27% in the SoCAB. NOx posterior emissions were 40% lower on weekends relative to weekdays. The CO2 posterior estimates were 183 Tg yr−1 in SoCAB. A flight during ITCT (Intercontinental Transport and Chemical Transformation in 2002 was used to estimate emissions in the LA Basin in 2002. From 2002 to 2010, the CO and NOx posterior emissions decreased by 41% and 37%, respectively, in agreement with previous studies. Over the same time period, CO2 emissions increased by 10% in LA County but decreased by 4% in the SoCAB, a statistically insignificant change. Overall, the posterior estimates were in good agreement with the California Air Resources Board (CARB inventory, with differences of 15% or less. However, the posterior spatial distribution in the basin was significantly different from CARB for NOx emissions. WRF-Chem mesoscale chemical-transport model simulations allowed an evaluation of differences in chemistry using different inventory assumptions, including NEI 2005, a gridded CARB

  14. Sensitivity of simulated CO2 concentration to regridding of global fossil fuel CO2 emissions

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2014-06-01

    Full Text Available Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Finite grid resolution can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. We test these mismatches by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are: (1 a commonly-used method that allocates emissions to gridcells with no attempt to ensure dynamical consistency with atmospheric transport; (2 an improved method that reallocates emissions to gridcells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from −30.3 Tg C gridcell−1 yr−1 (−3.39 kg C m−2 yr−1 to +30.0 Tg C gridcell−1 yr−1 (+2.6 kg C m−2 yr−1 along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding −32 ppm. The differences implied by not accounting for this dynamical consistency problem are largest at monitoring sites proximal to large coastal urban areas and point sources. These results suggest that studies comparing simulated to observed atmospheric CO2 concentration, such as atmospheric CO2 inversions, must take measures to correct for this potential

  15. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Directory of Open Access Journals (Sweden)

    C. Lac

    2013-05-01

    Full Text Available Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is a challenging and interesting task needed to be performed in order to utilise CO2 measurements in an atmospheric inverse framework and to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town Energy Balance (TEB urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs surface scheme, allowing a full interaction of CO2 modelling between the surface and the atmosphere. Statistical scores show a good representation of the urban heat island (UHI with stronger urban–rural contrasts on temperature at night than during the day by up to 7 °C. Boundary layer heights (BLH have been evaluated on urban, suburban and rural sites during the campaign, and also on a suburban site over 1 yr. The diurnal cycles of the BLH are well captured, especially the onset time of the BLH increase and its growth rate in the morning, which are essential for tall tower CO2 observatories. The main discrepancy is a small negative bias over urban and suburban sites during nighttime (respectively 45 m and 5 m, leading to a few overestimations of nocturnal CO2 mixing ratios at suburban sites and a bias of +5 ppm. The diurnal CO2 cycle is generally well captured for all the sites. At the Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the atmospheric boundary layer (ABL growth reaches the measurement height. At suburban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a strong spatio-temporal variability. A

  16. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Riette, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2013-05-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is a challenging and interesting task needed to be performed in order to utilise CO2 measurements in an atmospheric inverse framework and to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 modelling between the surface and the atmosphere. Statistical scores show a good representation of the urban heat island (UHI) with stronger urban-rural contrasts on temperature at night than during the day by up to 7 °C. Boundary layer heights (BLH) have been evaluated on urban, suburban and rural sites during the campaign, and also on a suburban site over 1 yr. The diurnal cycles of the BLH are well captured, especially the onset time of the BLH increase and its growth rate in the morning, which are essential for tall tower CO2 observatories. The main discrepancy is a small negative bias over urban and suburban sites during nighttime (respectively 45 m and 5 m), leading to a few overestimations of nocturnal CO2 mixing ratios at suburban sites and a bias of +5 ppm. The diurnal CO2 cycle is generally well captured for all the sites. At the Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the atmospheric boundary layer (ABL) growth reaches the measurement height. At suburban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a strong spatio-temporal variability. A sensitivity test without

  17. Macroalgal Performance and Competition under Elevated CO2

    OpenAIRE

    Hofmann, Laurie Carol

    2012-01-01

    Since the industrial revolution, atmospheric carbon dioxide (CO2) concentrations have been increasing, and the surface waters of the global oceans have absorbed 30% of the anthropogenic CO2 released into the atmosphere. A higher CO2 concentration in surface ocean waters shifts the carbon chemistry, resulting in higher concentrations of bicarbonate ions (HCO3-) and protons (H ) and lower concentrations of carbonate ions (CO32-). Such a shift in ocean carbon chemistry decreases the pH and the s...

  18. Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0: applications to numerical weather forecasting and the CO2 budget in South America

    Directory of Open Access Journals (Sweden)

    D. S. Moreira

    2013-08-01

    Full Text Available This article presents the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. This new numerical system is denominated JULES-CCATT-BRAMS. We demonstrate the performance of this new model system in relation to several meteorological variables and the CO2 mixing ratio over a large part of South America, focusing on the Amazon basin. The evaluation was conducted for two time periods, the wet (March and dry (September seasons of 2010. The model errors were calculated in relation to meteorological observations at conventional stations in airports and automatic stations. In addition, CO2 mixing ratios in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with observations obtained with airborne instruments. The results of this study show that the JULES-CCATT-BRAMS modeling system provided a significant gain in performance for the considered atmospheric fields relative to those simulated by the LEAF (version 3 surface model originally employed by CCATT-BRAMS. In addition, the new system significantly increases the ability to simulate processes involving air–surface interactions, due to the ability of JULES to simulate photosynthesis, respiration and dynamic vegetation, among other processes. We also discuss a wide range of numerical studies involving coupled atmospheric, land surface and chemistry processes that could be done with the system introduced here. Thus, this work presents to the scientific community a free modeling tool, with good performance in comparison with observational data and reanalysis model data, at least for the region and time period discussed here. Therefore, in principle, this model is able to produce atmospheric hindcast/forecast simulations at different spatial resolutions for any time period and any region of the globe.

  19. An in vitro evaluation of the responses of human osteoblast-like SaOs-2 cells on SLA titanium surfaces irradiated by different powers of CO2 lasers.

    Science.gov (United States)

    Ayubianmarkazi, Nader; Karimi, Mohammadreza; Koohkan, Shima; Sanasa, Armand; Foroutan, Tahereh

    2015-11-01

    Bacterial biofilms have been identified as the primary etiological factor for the development and progression of peri-implantitis. Lasers have been shown to remove bacterial plaque from titanium surfaces effectively and can restore its biocompatibility without damaging these surfaces. Therefore, the aim of this study was to evaluate the responses (i.e., the cell viability and morphology) of human osteoblast-like SaOs-2 cells to sandblasted, large grit, and acid-etched (SLA) titanium surfaces irradiated by CO2 lasers at two different power outputs. A total of 24 SLA disks were randomly radiated by CO2 lasers at either 6 W (group 1, 12 disks) or 8 W (group 2, 12 disks). Non-irradiated disks were used as a control group (four disks). The cell viability rates of the SaOs-2 cells in the control and study groups (6 and 8 W) were 0.33 ± 0.00, 0.24 ± 0.11, and 0.2372 ± 0.09, respectively (P SLA titanium surfaces.

  20. Optimization of supercritical CO2 extraction of astaxanthin from pacific white shrimp(Litopenaeus vannamei) using response surface methodology%超临界CO2萃取南美白对虾虾青素的工艺优化

    Institute of Scientific and Technical Information of China (English)

    杨霞; 张志胜; 郑乾魏; 祖铁红; 淑英

    2013-01-01

    In order to improve the extraction yield and content of astaxanthin, supercritical CO2 fluid extraction was used to extract astaxanthin from the head of Pacific White Shrimp, high performance liquid chromatography (HPLC) was adopted to determine the content of astaxanthin after saponification, the influence of extraction parameters on the extraction yield and astaxanthin content was determined by single factor test, then response surface method was employed to optimize technical parameters. The results showed that the influence of extraction parameters on the extraction yield of astaxanthin was not significant(p>0.05),but significant on the astaxanthin content (p<0.05). When the particle size of material was 40 mesh, moisture content was 9%, the theory optimum conditions for extraction astaxanthin with supercritical CO2 extraction were confirmed as follow:pressure 403.95 Pa, extraction temperature 39.95 , CO℃ 2 flow rate 1.16 L/min, under the conditions, the astaxanthin content was 796.3 mg/g. In application, the astaxanthin content in validation test was 789.61 mg/g when the extraction pressure was 400 Pa, the extraction temperature was 40 and the CO℃ 2 flow rate was 1.2 L/min. The results can provide a reference for extraction and purification of astaxanthin.%  为提高虾青素萃取物得率和虾青素纯度,采用超临界CO2萃取南美白对虾虾头废弃物中的虾青素,皂化后用高效液相色谱对虾青素含量进行测定。单因素试验确定萃取参数对虾青素萃取物得率和虾青素纯度的影响,然后进一步运用响应面法对萃取工艺参数进行优化。结果表明:超临界CO2萃取工艺参数对虾青素萃取物得率影响不显著(P>0.05),但对虾青素纯度影响显著(P<0.05);物料粒径40目,质量含水率9%时,响应面理论优化最佳萃取参数为萃取压力403.95 Pa,萃取温度39.95℃,CO2流量1.16 L/min,虾青素纯度为796.3mg/g。结合实际应用

  1. Enzymes in CO2 Capture

    DEFF Research Database (Denmark)

    Fosbøl, Philip Loldrup; Gladis, Arne; Thomsen, Kaj

    of carbon capture is the application of enzymes for acceleration of typically slow ternary amines or inorganic carbonates. There is a hidden potential to revive currently infeasible amines which have an interesting low energy consumption for regeneration but too slow kinetics for viable CO2 capture. The aim......The enzyme Carbonic Anhydrase (CA) can accelerate the absorption rate of CO2 into aqueous solutions by several-fold. It exist in almost all living organisms and catalyses different important processes like CO2 transport, respiration and the acid-base balances. A new technology in the field...... of this work is to discuss the measurements of kinetic properties for CA promoted CO2 capture solvent systems. The development of a rate-based model for enzymes will be discussed showing the principles of implementation and the results on using a well-known ternary amine for CO2 capture. Conclusions...

  2. CO2 Sequestration short course

    Energy Technology Data Exchange (ETDEWEB)

    DePaolo, Donald J. [Lawrence Berkeley National Laboratory; Cole, David R [The Ohio State University; Navrotsky, Alexandra [University of California-Davis; Bourg, Ian C [Lawrence Berkeley National Laboratory

    2014-12-08

    Given the public’s interest and concern over the impact of atmospheric greenhouse gases (GHGs) on global warming and related climate change patterns, the course is a timely discussion of the underlying geochemical and mineralogical processes associated with gas-water-mineral-interactions encountered during geological sequestration of CO2. The geochemical and mineralogical processes encountered in the subsurface during storage of CO2 will play an important role in facilitating the isolation of anthropogenic CO2 in the subsurface for thousands of years, thus moderating rapid increases in concentrations of atmospheric CO2 and mitigating global warming. Successful implementation of a variety of geological sequestration scenarios will be dependent on our ability to accurately predict, monitor and verify the behavior of CO2 in the subsurface. The course was proposed to and accepted by the Mineralogical Society of America (MSA) and The Geochemical Society (GS).

  3. Membraneless water filtration using CO2

    Science.gov (United States)

    Shin, Sangwoo; Shardt, Orest; Warren, Patrick; Stone, Howard

    2016-11-01

    Water purification technologies such as ultrafiltration and reverse osmosis utilize porous membranes to remove suspended particles and solutes. These membranes, however, cause many drawbacks such as a high pumping cost and a need for periodic replacement due to fouling. Here we show an alternative membraneless method for separating suspended particles by exposing the colloidal suspension to CO2. Dissolution of CO2 into the suspension creates solute gradients that drive phoretic motion of particles, or so-called diffusiophoresis. Due to the large diffusion potential built up by the dissociation of carbonic acid, colloidal particles move either away from or towards the gas-liquid interface depending on their surface charge. Our findings suggest a means to separate particles without membranes or filters, thus reducing operating and maintenance costs. Using the directed motion of particles induced by exposure to CO2, we demonstrate a scalable, continuous flow, membraneless particle filtration process that exhibits very low pressure drop and is essentially free from fouling.

  4. On the proportionality between global temperature change and cumulative CO2 emissions during periods of net negative CO2 emissions

    Science.gov (United States)

    Zickfeld, Kirsten; MacDougall, Andrew H.; Damon Matthews, H.

    2016-05-01

    Recent research has demonstrated that global mean surface air warming is approximately proportional to cumulative CO2 emissions. This proportional relationship has received considerable attention, as it allows one to calculate the cumulative CO2 emissions (‘carbon budget’) compatible with temperature targets and is a useful measure for model inter-comparison. Here we use an Earth system model to explore whether this relationship persists during periods of net negative CO2 emissions. Negative CO2 emissions are required in the majority of emissions scenarios limiting global warming to 2 °C above pre-industrial, with emissions becoming net negative in the second half of this century in several scenarios. We find that for model simulations with a symmetric 1% per year increase and decrease in atmospheric CO2, the temperature change (ΔT) versus cumulative CO2 emissions (CE) relationship is nonlinear during periods of net negative emissions, owing to the lagged response of the deep ocean to previously increasing atmospheric CO2. When corrected for this lagged response, or if the CO2 decline is applied after the system has equilibrated with the previous CO2 increase, the ΔT versus CE relationship is close to linear during periods of net negative CO2 emissions. A proportionality constant—the transient climate response to cumulative carbon emissions (TCRE)- can therefore be calculated for both positive and net negative CO2 emission periods. We find that in simulations with a symmetric 1% per year increase and decrease in atmospheric CO2 the TCRE is larger on the upward than on the downward CO2 trajectory, suggesting that positive CO2 emissions are more effective at warming than negative emissions are at subsequently cooling. We also find that the cooling effectiveness of negative CO2 emissions decreases if applied at higher atmospheric CO2 concentrations.

  5. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Energy Technology Data Exchange (ETDEWEB)

    Nassar, Ray [University of Toronto; Jones, DBA [University of Toronto; Suntharalingam, P [University of East Anglia, Norwich, United Kingdom; Chen, j. [University of Toronto; Andres, Robert Joseph [ORNL; Wecht, K. J. [Harvard University; Yantosca, R. M. [Harvard University; Kulawik, SS [Jet Propulsion Laboratory, Pasadena, CA; Bowman, K [Jet Propulsion Laboratory, Pasadena, CA; Worden, JR [Jet Propulsion Laboratory, Pasadena, CA; Machida, T [National Institute for Environmental Studies, Japan; Matsueda, H [Meteorological Research Institute, Japan

    2010-01-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth s carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (0.19 PgC yr 1), 3-D spatially-distributed emissions from aviation (0.16 PgC yr 1), and 3-D chemical production of CO2 (1.05 PgC yr 1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (10%) with a complex spatial structure

  6. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Directory of Open Access Journals (Sweden)

    K. W. Bowman

    2010-12-01

    Full Text Available The use of global three-dimensional (3-D models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01 CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C yr−1, 3-D spatially-distributed emissions from aviation (~0.16 Pg C yr−1, and 3-D chemical production of CO2 (~1.05 Pg C yr−1. Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May–June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%, while the inclusion of CO2 chemical production (and the surface correction is shown to decrease the latitudinal gradient by about 0.40 ppm (~10% with a complex

  7. A Multi-scale Approach for CO2 Accounting and Risk Analysis in CO2 Enhanced Oil Recovery Sites

    Science.gov (United States)

    Dai, Z.; Viswanathan, H. S.; Middleton, R. S.; Pan, F.; Ampomah, W.; Yang, C.; Jia, W.; Lee, S. Y.; McPherson, B. J. O. L.; Grigg, R.; White, M. D.

    2015-12-01

    Using carbon dioxide in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce carbon sequestration costs in the absence of greenhouse gas emissions policies that include incentives for carbon capture and storage. This study develops a multi-scale approach to perform CO2 accounting and risk analysis for understanding CO2 storage potential within an EOR environment at the Farnsworth Unit of the Anadarko Basin in northern Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil-water flow and transport in the Marrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2 injection rate, CO2 first breakthrough time, CO2 production rate, cumulative net CO2 storage, cumulative oil and CH4 production, and water injection and production rates. A global sensitivity analysis indicates that reservoir permeability, porosity, and thickness are the major intrinsic reservoir parameters that control net CO2 injection/storage and oil/CH4 recovery rates. The well spacing (the distance between the injection and production wells) and the sequence of alternating CO2 and water injection are the major operational parameters for designing an effective five-spot CO2-EOR pattern. The response surface analysis shows that net CO2 injection rate increases with the increasing reservoir thickness, permeability, and porosity. The oil/CH4 production rates are positively correlated to reservoir permeability, porosity and thickness, but negatively correlated to the initial water saturation. The mean and confidence intervals are estimated for quantifying the uncertainty ranges of the risk metrics. The results from this study provide useful insights for understanding the CO2 storage potential and the corresponding risks of commercial-scale CO2-EOR fields.

  8. Connecting CO2. Feasibility study CO2 network Southwest Netherlands; Connecting CO2. Haalbaarheidsstudie CO2-netwerk Zuidwest-Nederland

    Energy Technology Data Exchange (ETDEWEB)

    Rutten, M.

    2009-06-10

    An overview is given of supply and demand of CO2 in the region Southwest Netherlands and the regions Antwerp and Gent in Belgium. Also attention is paid to possible connections between these regions [Dutch] Een inventarisatie wordt gegeven van vraag en aanbod van CO2 in de regio Zuidwest- Nederland en de regios Antwerpen en Gent in Belgie. Ook worden mogelijke koppelingen tussen de regios besproken.

  9. A stable metal-organic framework with suitable pore sizes and rich uncoordinated nitrogen atoms on the internal surface of micropores for highly efficient CO2 capture

    NARCIS (Netherlands)

    Bao, S.J.; Krishna, R.; He, Y.B.; Qin, J.S.; Su, Z.M.; Li, S.L.; Xie, W.; Du, D.Y.; He, W.W.; Zhang, S.R.; Lan, Y.Q.

    2015-01-01

    An air-stable tetrazolate-containing framework, [ZN(2)L(2)]center dot 2DMF (NENU-520, H2L = 4-(1H-tetrazole-5-yl) biphenyl-4-carboxylic acid), with uncoordinated N atoms on its internal surface was solvothermally synthesized and structurally characterized. This metal-organic framework (MOF)

  10. Electric field controlled CO2 capture and CO2/N2 separation on MoS2 monolayers.

    Science.gov (United States)

    Sun, Qiao; Qin, Gangqiang; Ma, Yingying; Wang, Weihua; Li, Ping; Du, Aijun; Li, Zhen

    2017-01-07

    Developing new materials and technologies for efficient CO2 capture, particularly for separation of CO2 post-combustion, will significantly reduce the CO2 concentration and its impacts on the environment. A challenge for CO2 capture is to obtain high performance adsorbents with both high selectivity and easy regeneration. Here, CO2 capture/regeneration on MoS2 monolayers controlled by turning on/off external electric fields is comprehensively investigated through a density functional theory calculation. The calculated results indicate that CO2 forms a weak interaction with MoS2 monolayers in the absence of an electric field, but strongly interacts with MoS2 monolayers when an electric field of 0.004 a.u. is applied. Moreover, the adsorbed CO2 can be released from the surface of MoS2 without any energy barrier once the electric field is turned off. Compared with the adsorption of CO2, the interactions between N2 and MoS2 are not affected significantly by the external electric fields, which indicates that MoS2 monolayers can be used as a robust absorbent for controllable capture of CO2 by applying an electric field, especially to separate CO2 from the post-combustion gas mixture where CO2 and N2 are the main components.

  11. First-Principles Study of Photochemical Activation of CO2 by Ti-based Oxides

    Science.gov (United States)

    He, Haiying; Zapol, Peter; Curtiss, Larry

    2013-03-01

    The photochemical conversion of CO2 and H2O into energy-bearing hydrocarbon fuels provides an attractive way of mitigating the green-house gas CO2 and utilizing solar energy as a sustainable energy source. However, due to the high reduction potential and chemical inertness of CO2 molecules, the conversion rate of CO2 is impractically low. The activation of CO2 is critical in facilitating further reactions. By carrying out first-principles calculations of reaction pathways from CO2 to CO2-anions on Ti-based oxides including zeolites in the presence of photoexcited electrons, we have studied the initial step of CO2 activation via 1e transfer. It is shown that the CO2 reactivity of these surfaces strongly depends on the crystal structure, surface orientation, and presence of defects. This opens a new dimension in surface structure modification to enhance the CO2 adsorption and reduction on semiconductor surfaces.

  12. Ondes de surface transverses sur plaques piézoélectriques avec réseaux de bandes metalliques déposés sur les 2 faces

    Science.gov (United States)

    Ballandras, S.; Gavignet, E.; Bigler, E.

    1995-09-01

    A theoretical model has been implemented to study surface transverse waves propagating on piezoelectric plates of finite thickness with thin metal strip gratings on both sides. Calculations have been performed for AT-cuts of quartz of thickness varying from 140 to 120 μm. The spatial period of the gratings was fixed to 20 μm (acoustic wavelength equal to 40 μm). The dispersion curve relating the angular frequency to the wavenumber presents more than one stopband as found in the usual analyses on semi-infinite substrates. These multiple high-frequency stopbands allow to design and realize high stability resonators or highly sensitive sensors for gravimetry, accelerometer applications, etc. Un modèle théorique a été mis en œuvre pour l'étude des propriétés des ondes de surface transverses se propageant sur des plaques piézoélectriques d'épaisseur finie avec des réseaux de fines bandes métalliques déposés sur chaque face. Les calculs ont été effectués pour des plaques de quartz voisines de la coupe AT et d'épaisseur variant de 140 à 120 μm. La périodicité des réseaux en regard a été fixée à 20 μm (longueur d'onde acoustique 40 μm). La courbe de dispersion reliant la pulsation au nombre d'ondes présente plusieurs bandes d'arrêt incluant celle habituellement mise en évidence pour un substrat semi-infini. L'existence de ces multiples bandes d'arrêt haute fréquence ouvre de nouvelles perspectives pour la réalisation de résonateurs ultrastables ou de capteurs de très grande sensibilité gravimétrique, accélérométrique, etc.

  13. Etude de la capture du CO2 par absorption physique dans les systèmes de production d'électricité basés sur la gazéification du charbon intégrée à un cycle combiné

    OpenAIRE

    Descamps, Cathy

    2004-01-01

    The reduction of greenhouse gas emissions call for new strategies toward the use of fossil fuels. The study is aimed to assess the possibility of reducing CO2 emission from an Integrated Gasification Combined Cycle plant. A comparative study of the CO2 capture processes retained in literature (MEA-MDEA, AMP, N-Methyl-Pyrrolidone and methanol) led to the choice of the physical absorption by methanol. The simulation of the IGCC with CO2 capture was carried out with the Aspen Plus; La volonté de...

  14. Investigation of the interfacial properties for CO2-methanol and CO2-ethanol mixtures%CO2-甲醇和CO2-乙醇体系的界面性质

    Institute of Scientific and Technical Information of China (English)

    付东

    2011-01-01

    An equation of state (EOS) applicable for the interfacial properties of CO2-methanol and CO2-ethanol mixtures was established by combining the cross-association EOS and the density gradient theory (DGT). The correlated surface tensions of CO2-ethanol mixtures agreed well with the experimental data. The results illustrated the temperature and pressure dependence of the cross-association between CO2 and alcohol hydroxyls in the whole vapor-liquid surface, and the influence of the cross-association on the calculation of the surface tensions of binary mixtures.%在交叉缔合的均相状态方程的基础上,结合密度梯度理论(density gradient theory,DGT),建立了适用于CO2-甲醇和CO2-乙醇二元体系界面性质研究的状态方程,对CO2-乙醇体系表面张力的关联结果与实验值吻合良好.阐明了CO2分子与甲醇分子和乙醇分子之间的交叉缔合作用对二元体系表面张力计算结果的影响,以及界面相中CO2与醇羟基之间的交叉缔合与温度和压力之间的关系.

  15. A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, L.H.; Wielopolski, L.; Dobeck, L. M.; Repasky, K. S.; Nehrir, A. R.; Humphries, S. D.; Barr, J. L.; Keith, C. J.; Shaw, J. A.; Rouse, J. H.; Cunningham, A. B.; Benson, S. M.; Oldenburg, C. M.; Lewicki, J. L.; Wells, A. W.; Diehl, J. R.; Strazisar, B. R.; Fessenden, J. E.; Rahn, T. A.; Amonette, J. E.; Barr, J. L.; Pickles, W. L.; Jacobson, J. D.; Silver, E. A.; Male, E. J.; Rauch, H. W.; Gullickson, K. S.; Trautz, R.; Kharaka, Y.; Birkholzer, J.

    2010-03-01

    A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO{sub 2} transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO{sub 2} release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO{sub 2} transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO{sub 2} from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO{sub 2} through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented.

  16. CO2-Responsive Polymer-Functionalized Au Nanoparticles for CO2 Sensor.

    Science.gov (United States)

    Ma, Ying; Promthaveepong, Kittithat; Li, Nan

    2016-08-16

    Metallic nanoparticles (NPs) coated with stimuli-responsive polymers (SRPs) exhibit tunable optical properties responding to external stimuli and show promising sensing applications. We present a new CO2-responsive polymer, poly(N-(3-amidino)-aniline) (PNAAN), coated gold NPs (AuNPs) synthesized by directly reducing HAuCl4 with a CO2-responsive monomer N-(3-amidino)-aniline (NAAN). The amidine group of PNAAN can be protonated into a hydrophilic amidinium group by dissolved CO2 (dCO2). This induces the PNAAN to swell and detach from the AuNP surface, resulting in AuNP aggregation and color change. By monitoring the UV absorbance change of AuNPs, a sensitive dCO2 sensor with a linear range of 0.0132 to 0.1584 hPa and a limit of detection (LOD) of 0.0024 hPa is developed. This method shows dramatic improvement in sensitivity and convenience of sample preparation compared with the previously reported dCO2 sensor.

  17. Leak Path Development in CO2 Wells

    Science.gov (United States)

    Torsater, M.; Todorovic, J.; Opedal, N.; Lavrov, A.

    2014-12-01

    Wells have in numerous scientific works been denoted the "weak link" of safe and cost-efficient CO2 Capture and Storage (CCS). Whether they are active or abandoned, all wells are man-made intrusions into the storage reservoir with sealing abilities depending on degradable materials like steel and cement. If dense CO2 is allowed to expand (e.g. due to leakage) it will cool down its surroundings and cause strong thermal and mechanical loading on the wellbore. In addition, CO2 reacts chemically with rock, cement and steel. To ensure long-term underground containment, it is therefore necessary to study how, why, where and when leakage occurs along CO2wells. If cement bonding to rock or casing is poor, leak paths can form already during drilling and completion of the well. In the present work, we have mapped the bonding quality of cement-rock and cement-steel interfaces - and measured their resistance towards CO2 flow. This involved a large experimental matrix including different rocks, steels, cement types and well fluids. The bonding qualities were measured on composite cores using micro computed tomography (µ-CT), and CO2 was flooded through the samples to determine leakage rates. These were further compared to numerical simulations of leakage through the digitalized µ-CT core data, and CO2chemical interactions with the materials were mapped using electron microscopy. We also present a new laboratory set-up for measuring how well integrity is affected by downhole temperature variations - and we showcase some initial results. Our work concludes that leak path development in CO2 wells depends critically on the drilling fluids and presflushes/spacers chosen already during drilling and completion of a well. Fluid films residing on rock and casing surfaces strongly degrade the quality of cement bonding. The operation of the well is also important, as even slight thermal cycling (between 10°C and 95°C on casing) leads to significant de-bonding of the annular cement.

  18. Our trial to develop a risk assessment tool for CO2 geological storage (GERAS-CO2GS)

    Science.gov (United States)

    Tanaka, A.; Sakamoto, Y.; Komai, T.

    2012-12-01

    We will introduce our researches about to develop a risk assessment tool named 'GERAS-CO2GS' (Geo-environmental Risk Assessment System, CO2 Geological Storage Risk Assessment System) for 'Carbon Dioxide Geological Storage (Geological CCS)'. It aims to facilitate understanding of size of impact of risks related with upper migration of injected CO2. For gaining public recognition about feasibility of Geological CCS, quantitative estimation of risks is essential, to let public knows the level of the risk: whether it is negligible or not. Generally, in preliminary hazard analysis procedure, potential hazards could be identified within Geological CCS's various facilities such as: reservoir, cap rock, upper layers, CO2 injection well, CO2 injection plant and CO2 transport facilities. Among them, hazard of leakage of injected C02 is crucial, because it is the clue to estimate risks around a specific injection plan in terms of safety, environmental protection effect and economy. Our risk assessment tool named GERAS-CO2GS evaluates volume and rate of retention and leakage of injected CO2 in relation with fractures and/or faults, and then it estimates impact of seepages on the surface of the earth. GERAS-CO2GS has four major processing segments: (a) calculation of CO2 retention and leakage volume and rate, (b) data processing of CO2 dispersion on the surface and ambient air, (c) risk data definition and (d) evaluation of risk. Concerning to the injection site, we defined a model, which is consisted from an injection well and a geological strata model: which involves a reservoir, a cap rock, an upper layer, faults, seabed, sea, the surface of the earth and the surface of the sea. For retention rate of each element of CO2 injection site model, we use results of our experimental and numerical studies on CO2 migration within reservoirs and faults with specific lithological conditions. For given CO2 injection rate, GERAS-CO2GS calculates CO2 retention and leakage of each segment

  19. CO2 injection along a pipeline with transient approach

    Science.gov (United States)

    Bezos, Víctor; Carrera, Jesús; Slooten, Luit Jan; Silva, Orlando; Bear, Jacob; Kitro-Belinkov, Myra

    2013-04-01

    CO2 geological sequestration involves several processes. One of the more relevant of these processes is the CO2 injection along a pipeline, because it links the capture and transport of CO2 with its deep geological storage. The knowledge of the CO2 behavior within injection and monitoring wells is essential for designing efficient CO2 storage strategies. In particular, a thorough modeling and simulation of CO2 flow through the injection pipe is required to define operational protocols and to design the surface CO2 conditioning facilities. Much work has been performed on modeling the steady state multiphase flow in wellbores during CO2 injection. However, relevant problems, including the displacement of the initial brine in the injection well, or the upwards flow of CO2 during a push-pull test, require the modeling of transient conditions, which is the goal of the present work. Here, we present the governing equations and preliminary results for the modeling of dynamic non isothermal CO2 flow through an injection well, including displacement of the initial brine. The model considers continuity, momentum and energy equations, together with equations of state and some thermodynamic relations. These equations are solved using the simulation framework "Proost", which implements the finite element method. The code is verified by comparison with a steady-state solver for a range of surface injection conditions. The results obtained show pressure, velocity and temperature evolution, which allows quantifying the phase changes that gradually experiment the CO2 through the injection pipe. We find the surface pressure required initially is much higher than steady-state because heat exchange with the formation reduces significantly the density of CO2 at the borehole.

  20. Gases (CH4, CO2 and N2 and pore water chemistry in the surface sediments of Lake Orta, Italy: acidification effects on C and N gas cycling

    Directory of Open Access Journals (Sweden)

    Donald D. ADAMS

    2001-02-01

    Full Text Available Lake Orta, a subalpine, warm monomictic lake in northwestern Italy was heavily polluted from rayon factory discharges of ammonium and copper since 1926. In the 1950s accumulations of contaminants resulted in whole lake pHs of 3.8-4.0 from ammonium oxidation. Partial remediation started in the 1950s, but by 1985-89 the water remained acidified at pHs of 4.0. Artificial liming (14,500 t in 1989-90 resulted in improved water quality and substantial recovery of the biological community. Sediment gases, sampled in 1989 before liming, from the lake's four basins showed severe inhibition of methanogenesis (CH4 = 0.0-0.15 mM in the surface sediments (0.5-5 cm of the southern basin, location of the plant effluent, as compared to the deep central and northern basins (0.9-1.4 mM. Four years after liming, cores collected in 1994 near the 1989 southern basin sites showed a slight change in surface sediment methane (0.07-0.82 mM, yet suggested continual sediment toxicity, at least to carbon cycling through methanogenesis. Calculations of diffuse flux of CH4 at the sediment-water interface (SWI in 1989 were 6.6-7.4 mM m-2 day-1 for the central and northern basins and 0.13 for the southern basin. CH4 fluxes increased 16x to 2 mM m-2 day-1 in 1994 in the southern basin, possibly from remediation of near surface sediments. The impact of pollution on denitrification (formation of sediment N2 gas was not so obvious since two processes could counteract each other (high NO3 - stimulating denitrification versus possible negative effects from acidity and metals. The calculated flux of N2 from the southern basin sediments increased 5x four years after liming compared to the period of acidification, suggesting possible toxicity towards denitrifiers during the earlier period. Core overlying water (0.68 mM exhibited N2 concentrations close to saturation, while most surface sediments were twice as much (1.5 mM. Surface (0-6 cm sediment N2 was similar at most sites, with the

  1. Partial pressure of carbon dioxide (pCO2), temperature, salinity and other variables collected from surface underway observations using shower head equilibrator, carbon dioxide gas detector, and other instruments from container ship Cap Vilano in the Pacific Ocean from 2013-02-01 to 2013-06-06 (NCEI Accession 0132054)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains underway measurements of pCO2, salinity, sea surface temperature, and other parameters were collected during 3 trans-Pacific crossings...

  2. Partial pressure of carbon dioxide (pCO2), temperature, salinity and other variables collected from surface underway observations using shower head equilibrator, carbon dioxide gas detector, and other instruments from container ship Cap Blanche in the Pacific Ocean from 2014-02-01 to 2014-11-26 (NCEI Accession 0132047)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains underway measurements of pCO2, salinity, sea surface temperature, and other parameters were collected during 6 trans-Pacific crossings...

  3. Partial pressure of carbon dioxide (pCO2), temperature, salinity and other variables collected from surface underway observations using shower head equilibrator, carbon dioxide gas detector, and other instruments from 4 trans-Pacific crossings onboard container ship Cap Blanche in the Pacific Ocean from 2015-03-28 to 2015-12-04 (NCEI Accession 0141304)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Underway measurements of pCO2, salinity, sea surface temperature, and other parameters were collected during 4 trans-Pacific crossings in 2015 on the container ship...

  4. Partial pressure of carbon dioxide (pCO2), temperature, salinity and other variables collected from surface underway observations using shower head equilibrator, carbon dioxide gas detector, and other instruments from NOAA Ship Oscar Dyson in the Bering Sea and coast of Alaska from 2014-03-03 to 2014-08-13 (NCEI Accession 0132046)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains underway measurements of pCO2, salinity, sea surface temperature, and other parameters collected in 2014 on board NOAA Ship Oscar...

  5. Relation of dynamic changes in CO2 of modified atmosphere packaging (MAP) of fresh grass carp steaks to muscle surface pH%草鱼段气调包装袋内CO2动态变化与鱼体肌肉表面pH值关系

    Institute of Scientific and Technical Information of China (English)

    周冬香; 周培根; 陈椒

    2002-01-01

    @@ 分别测定草鱼段气调包装袋内CO2气体动态变化与鱼体的肌肉表面pH值,得出了气体的动态变化与pH值关系.在草鱼的气调包装中,采用CO2、O2和N2作为混合气体,其中CO2是一种抑菌气体.由于CO2溶解度较大,因此,CO2在鱼体中的溶解是产生抑菌效果的重要因素,也是引起气体组分变化的重要原因,影响鱼的贮藏效果.CO2被鱼体表面吸收后,水解生成碳酸,引起鱼体表面pH值下降,反映了CO2被鱼体吸收的量.

  6. Research on the abrasive wear resistance of YDCrMoV coating produced by CO2 shielded flux-cored wire surfacing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.

  7. CO2 emissions from German drinking water reservoirs.

    Science.gov (United States)

    Saidi, Helmi; Koschorreck, Matthias

    2017-03-01

    Globally, reservoirs are a significant source of atmospheric CO2. However, precise quantification of greenhouse gas emissions from drinking water reservoirs on the regional or national scale is still challenging. We calculated CO2 fluxes for 39 German drinking water reservoirs during a period of 22years (1991-2013) using routine monitoring data in order to quantify total emission of CO2 from drinking water reservoirs in Germany and to identify major drivers. All reservoirs were a net CO2 source with a median flux of 167gCm(-2)y(-1), which makes gaseous emissions a relevant process for the carbon budget of each reservoir. Fluxes varied seasonally with median fluxes of 13, 48, and 201gCm(-2)y(-1) in spring, summer, and autumn respectively. Differences between reservoirs appeared to be primarily caused by the concentration of CO2 in the surface water rather than by the physical gas transfer coefficient. Consideration of short term fluctuations of the gas transfer coefficient due to varying wind speed had only a minor effect on the annual budgets. High CO2 emissions only occurred in reservoirs with pHCO2 emissions correlated exponentially with pH but not with dissolved organic carbon (DOC). There was significant correlation between land use in the catchment and CO2 emissions. In total, German drinking water reservoirs emit 44000t of CO2 annually, which makes them a negligible CO2 source (CO2 emissions) in Germany.

  8. Enhanced CO2 Dissolution in Heterogeneous Porous Media

    Science.gov (United States)

    Daniels, K.; Neufeld, J. A.; Bickle, M. J.; Hallworth, M. A.

    2014-12-01

    Long-term and secure geological storage of CO2 through technologies such as Carbon Capture and Storage (CCS) within reservoirs is seen as a technological means to reduce anthropogenic CO2 emissions. The long-term viability of this technology is reliant on the structural and secondary trapping of supercritical CO2 within heterogeneous reservoirs. Secondary trapping, primarily through the dissolution of CO2 into ambient reservoir brine to produce a denser fluid, is capable of retaining CO2 in the subsurface and thus reducing the risks of storage. To model secondary trapping we need to understand how the flow of CO2 through heterogeneous reservoir rocks enhances dissolution of supercritical CO2 in reservoir brines. Here we experimentally investigate the dissolution of CO2 in reservoir brines in layered, heterogeneous geological formations. Using analogue experiments, designed to approximate an enhanced oil recovery (EOR) setting, the processes of mixing, dispersion and dissolution are examined. These are compared against test results from non-layered, homogeneous porous media experiments. We find that heterogeneities significantly enhance mixing, particularly between adjacent porous layers. During fluid propagation, pore-scale viscous fingers grow and retreat, thereby providing an increased surface area between the flow and the ambient reservoir fluid. This enhanced mixing is predicted to substantially increase the dissolution of CO2 in reservoir brines. Both permeability and viscosity differences are found to have a significant effect on the interface between the two fluids, and therefore the likely amount of dissolution of CO2.

  9. Target atmospheric CO2: Where should humanity aim?

    OpenAIRE

    Hansen, J.; Sato, M.; Kharecha, P.; Beerling, D.; Berner, R; Masson-Delmotte, V.; M. Pagani; Raymo, M.; Royer, D. L.; J. C. Zachos

    2008-01-01

    Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 450 +/- 100 ppm, a level that will be exceeded within decades, b...

  10. ACCURACY OF CO2 SENSORS

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J.; Faulkner, David; Sullivan, Douglas P.

    2008-10-01

    Are the carbon dioxide (CO2) sensors in your demand controlled ventilation systems sufficiently accurate? The data from these sensors are used to automatically modulate minimum rates of outdoor air ventilation. The goal is to keep ventilation rates at or above design requirements while adjusting the ventilation rate with changes in occupancy in order to save energy. Studies of energy savings from demand controlled ventilation and of the relationship of indoor CO2 concentrations with health and work performance provide a strong rationale for use of indoor CO2 data to control minimum ventilation rates1-7. However, this strategy will only be effective if, in practice, the CO2 sensors have a reasonable accuracy. The objective of this study was; therefore, to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. This article provides a summary of study methods and findings ? additional details are available in a paper in the proceedings of the ASHRAE IAQ?2007 Conference8.

  11. Correlations of the first and second derivatives of atmospheric CO2 with global surface temperature and the El Nino-Southern Oscillation respectively

    CERN Document Server

    Leggett, L M W

    2014-01-01

    Understanding current global climate requires an understanding of trends both in Earth's atmospheric temperature and the El Nino-Southern Oscillation (ENSO), a characteristic large-scale distribution of warm water in the tropical Pacific Ocean and the dominant mode of year-to-year climate variability (Holbrook et al. 2009. However, despite much effort, the average projection of current climate models has become statistically significantly different from the observed 21st century global surface temperature trend (Fyfe 2013)and has failed to reflect the statistically significant evidence that annual-mean global temperature has not risen in the 21st century (Fyfe 2013, Kosaka 2013). Modelling also provides a wide range of predictions for future ENSO variability, some showing an increase, others a decrease and some no change (Guilyardi, et al. 2012; Bellenger, 2013). Here we present correlations which include the current era and do not have these drawbacks. The correlations arise as follows. First it has been sho...

  12. Comparison of regional and ecosystem CO2 fluxes

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Søgaard, Henrik; Batchvarova, Ekaterina

    2009-01-01

    A budget method to derive the regional surface flux of CO2 from the evolution of the boundary layer is presented and applied. The necessary input for the method can be deduced from a combination of vertical profile measurements of CO2 concentrations by i.e. an airplane, successive radio-soundings...

  13. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

    of the simulated atmospheric CO2 across Denmark was, in particular, affected by the Danish terrestrial surface exchanges and its temporal variability. This study urges all future modelling studies of air–sea CO2 to include short-term variability in pCO2. To capture the full heterogeneity of the surface exchanges......It is scientifically well-established that the increase of atmospheric CO2 affects the entire globe and will lead to higher surface temperatures. Although anthropogenic CO2is emitted straight into the atmosphere, it does not all contribute to the existing atmospheric CO2 reservoir. Approximately 29......% is taken up by the global oceans, due to under-saturation of CO2 in the surface waters, while another 33 % is taken up by the terrestrial biosphere, via photosynthesis. In order to estimate the effects of increasing anthropogenic emissions of CO2 more accurately in the future, it is essential to understand...

  14. Biogeophysical effects of CO2 fertilization on global climate

    Science.gov (United States)

    Bala, G.; Caldeira, K.; Mirin, A.; Wickett, M.; Delire, C.; Phillips, T. J.

    2006-11-01

    CO2 fertilization affects plant growth, which modifies surface physical properties, altering the surface albedo, and fluxes of sensible and latent heat. We investigate how such CO2-fertilization effects on vegetation and surface properties would affect the climate system. Using a global three-dimensional climate-carbon model that simulates vegetation dynamics, we compare two multicentury simulations: a `Control' simulation with no emissions and a `Physiol-noGHG' simulation where physiological changes occur as a result of prescribed CO2 emissions, but where CO2-induced greenhouse warming is not included. In our simulations, CO2 fertilization produces warming; we obtain an annual- and global-mean warming of about 0.65 K (and land-only warming of 1.4 K) after 430 yr. This century-scale warming is mostly due to a decreased surface albedo associated with the expansion of the Northern Hemisphere boreal forests. On decadal timescales, the CO2 uptake by afforestation should produce a cooling effect that exceeds this albedo-based warming; but if the forests remain in place, the CO2-enhanced-greenhouse effect would diminish as the ocean equilibrates with the atmosphere, whereas the albedo effect would persist. Thus, on century timescales, there is the prospect for net warming from CO2 fertilization of the land biosphere. Further study is needed to confirm and better quantify our results.

  15. Uncertainty quantification for CO2 sequestration and enhanced oil recovery

    CERN Document Server

    Dai, Zhenxue; Fessenden-Rahn, Julianna; Middleton, Richard; Pan, Feng; Jia, Wei; Lee, Si-Yong; McPherson, Brian; Ampomah, William; Grigg, Reid

    2014-01-01

    This study develops a statistical method to perform uncertainty quantification for understanding CO2 storage potential within an enhanced oil recovery (EOR) environment at the Farnsworth Unit of the Anadarko Basin in northern Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil-water flow and reactive transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major uncertainty metrics: net CO2 injection, cumulative oil production, cumulative gas (CH4) production, and net water injection. A global sensitivity and response surface analysis indicates that reservoir permeability, porosity, and thickness are the major intrinsic reservoir parameters that control net CO2 injection/storage and oil/gas recovery rates. The well spacing and the initial water saturation also have large impact on the oil/gas recovery rates. Further, this study has revealed key insights into the potential behavior and the operational parameters of CO2 sequestration at CO2-EOR s...

  16. Method for tracing simulated CO2 leak in terrestrial environment with a 13CO2 tracer

    Science.gov (United States)

    Moni, Christophe; Rasse, Daniel

    2013-04-01

    Facilities for the geological storage of carbon dioxide (CO2) as part of carbon capture and storage (CCS) schemes will be designed to prevent any leakage from the defined 'storage complex'. However, developing regulations and guidance throughout the world (e.g. the EC Directive and the USEPA Vulnerability Evaluation Framework) recognize the importance of assessing the potential for environmental impacts from CO2 storage. RISCS, a European (FP7) project, aims to improve understanding of those impacts that could plausibly occur in the hypothetical case that unexpected leakage occurs. As part of the RISCS project the potential impacts that an unexpected CO2 leaks might have on a cropland ecosystems was investigated. A CO2 exposure field experiment based on CO2 injection at 85 cm depth under an oats culture was designed. To facilitate the characterization of the simulated leaking zone the gas used for injection was produced from natural gas and had a δ13C of -46‰. The aim of the present communication is to depict how the injected gas was traced within the soil-vegetation-atmosphere continuum using 13CO2 continuous cavity ring-down spectrometry (CRDS). Four subsurface experimental injection plots (6m x 3m) were set up. In order to test the effects of different intensity of leakage, the field experiment was designed as to create a longitudinal CO2 gradient for each plot. For this purpose gas supply pipes were inserted at one extremity of each plot at the base of a 45 cm thick layer of sand buried 40 cm below the surface under the clayey plough layer of Norwegian moraine soils. Soil CO2 concentration and isotopic signature were punctually recorded: 1) in the soil at 20 cm depth at 6 positions distributed on the central transect, 2) at the surface following a (50x50 cm) grid sampling pattern, and 3) in the canopy atmosphere at 10, 20, 30 cm along three longitudinal transects (seven sampling point per transect). Soil CO2 fluxes and isotopic signature were finally

  17. Density functional theory study of the interaction of H2O, CO2 and CO with the ZrO2 (111), Ni/ZrO2 (111), YSZ (111) and Ni/YSZ (111) surfaces

    Science.gov (United States)

    Cadi-Essadek, Abdelaziz; Roldan, Alberto; de Leeuw, Nora H.

    2016-11-01

    The triple phase boundary (TPB), where the gas phase, Ni particles and the yttria-stabilised zirconia (YSZ) surface meet, plays a significant role in the performance of solid oxide fuel cells (SOFC). Indeed, the key reactions take place at the TPB, where molecules such as H2O, CO2 and CO interact and react. We have systematically studied the interaction of H2O, CO2 and CO with the dominant surfaces of four materials that are relevant to SOFC, i.e. ZrO2(111), Ni/ZrO2(111), YSZ(111) and Ni/YSZ(111) of cubic ZrO2 stabilized with 9% of yttria (Y2O3). The study employed spin polarized density functional theory (DFT), taking into account the long-range dispersion forces. We have investigated up to five initial adsorption sites for the three molecules and have identified the geometries and electronic structures of the most stable adsorption configurations. We have also analysed the vibrational modes of the three molecules in the gas phase and compared them with the adsorbed molecules. A decrease of the wavenumbers of the vibrational modes for the three adsorbed molecules was observed, confirming the influence of the surface on the molecules' intra-molecular bonds. These results are in line with the important role of Ni in this system, in particular for the CO adsorption and activation. This document contains the binding energies at the non-equivalent adsorption sites for H2O, CO2 and CO molecules on ZrO2(111) (Figure S1 and Table S1), Ni/ZrO2(111) (Figure S2 and Table S2), YSZ(111) (Figure S3 and Table S3) and Ni/YSZ(111) (Figure S4 and Table S4). We have not reported here the zero point energy. This document also contains the ZrxOyHz clusters studied in Ref. 40 and discussed in our manuscript (Figure S5).

  18. High Redox Capacity of Al-Doped La1-x Srx MnO3-δ Perovskites for Splitting CO2 and H2 O at Mn-Enriched Surfaces.

    Science.gov (United States)

    Ezbiri, M; Becattini, V; Hoes, M; Michalsky, R; Steinfeld, A

    2017-01-26

    Perovskites are attractive candidates for the solar-driven thermochemical redox splitting of CO2 and H2 O into CO and H2 (syngas) and O2 . This work investigates the surface activity of La1-x Srx Mn1-y Aly O3-δ (0≤x≤1, 0≤y≤1) and La0.6 Ca0.4 Mn0.6 Al0.4 O3-δ . At 1623 K and 15 mbar O2 , the oxygen non-stoichiometry of La0.2 Sr0.8 Mn0.8 Al0.2 O3-δ increases with the strontium content and reaches a maximum of δ=0.351. X-ray photoelectron spectroscopy analysis indicates that manganese is the only redox-active metal at the surface. All La1-x Srx Mn1-y Aly O3-δ compositions exhibit surfaces enriched in manganese and depleted in strontium. We discuss how these compositional differences of the surface from the bulk lead to the beneficially higher reduction extents and lower strontium carbonate concentrations at the aluminum-doped surfaces. Using first principles calculations, we validate the experimental reduction trends and elucidate the mechanism of the partial electronic charge redistribution upon perovskite reduction.