WorldWideScience

Sample records for model simulated co2

  1. Simulation of atmospheric CO2 over Europe and western Siberia using the regional scale model REMO

    International Nuclear Information System (INIS)

    Chevillard, A.; Ciais, P.; Lafont, S.

    2002-01-01

    The spatial distribution and the temporal variability of atmospheric CO 2 over Europe and western Siberia are investigated using the regional atmospheric model, REMO. The model, of typical horizontal resolution 50 km, is part of a nested modelling framework that has been established as a concerted action during the EUROSIBERIAN CARBONFLUX project. In REMO, the transport of CO 2 is simulated together with climate variables, which offers the possibility of calculating at each time step the land atmosphere CO 2 fluxes as driven by the modelled meteorology. The uptake of CO 2 by photosynthesis is calculated using a light use efficiency formulation, where the absorbed photosynthetically active solar radiation is inferred from satellite measurements. The release of CO 2 from plant and soil respiration is driven by the simulated climate and assumed to be in equilibrium with photosynthesis over the course of one year. Fossil CO 2 emissions and air-sea fluxes within the model domain are prescribed, whereas the influence of sources outside the model domain is computed from as a boundary condition CO 2 fields determined a global transport model. The modelling results are compared against pointwise eddy covariance fluxes, and against atmospheric CO 2 records. We show that a necessary condition to simulate realistically the variability of atmospheric CO 2 over continental Europe is to account for the diurnal cycle of biospheric exchange. Overall, for the study period of July 1998, REMO realistically simulates the short-term variability of fluxes and of atmospheric mixing ratios. However, the mean CO 2 gradients from western Europe to western Siberia are not correctly reproduced. This latter deficiency points out the key role of boundary conditions in a limited-area model, as well as the need for using more realistic geographic mean patterns of biospheric carbon fluxes

  2. Modeling and Simulation of Nanoparticle Transport in Multiphase Flows in Porous Media: CO2 Sequestration

    KAUST Repository

    El-Amin, Mohamed

    2012-09-03

    Geological storage of anthropogenic CO2 emissions in deep saline aquifers has recently received tremendous attention in the scientific literature. Injected CO2 plume buoyantly accumulates at the top part of the deep aquifer under a sealing cap rock, and some concern that the high-pressure CO2 could breach the seal rock. However, CO2 will diffuse into the brine underneath and generate a slightly denser fluid that may induce instability and convective mixing. Onset times of instability and convective mixing performance depend on the physical properties of the rock and fluids, such as permeability and density contrast. The novel idea is to adding nanoparticles to the injected CO2 to increase density contrast between the CO2-rich brine and the underlying resident brine and, consequently, decrease onset time of instability and increase convective mixing. As far as it goes, only few works address the issues related to mathematical and numerical modeling aspects of the nanoparticles transport phenomena in CO2 storages. In the current work, we will present mathematical models to describe the nanoparticles transport carried by injected CO2 in porous media. Buoyancy and capillary forces as well as Brownian diffusion are important to be considered in the model. IMplicit Pressure Explicit Saturation-Concentration (IMPESC) scheme is used and a numerical simulator is developed to simulate the nanoparticles transport in CO2 storages.

  3. Progress in Modeling Global Atmospheric CO2 Fluxes and Transport: Results from Simulations with Diurnal Fluxes

    Science.gov (United States)

    Collatz, G. James; Kawa, R.

    2007-01-01

    Progress in better determining CO2 sources and sinks will almost certainly rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. Use of advanced data requires improved modeling and analysis capability. Under NASA Carbon Cycle Science support we seek to develop and integrate improved formulations for 1) atmospheric transport, 2) terrestrial uptake and release, 3) biomass and 4) fossil fuel burning, and 5) observational data analysis including inverse calculations. The transport modeling is based on meteorological data assimilation analysis from the Goddard Modeling and Assimilation Office. Use of assimilated met data enables model comparison to CO2 and other observations across a wide range of scales of variability. In this presentation we focus on the short end of the temporal variability spectrum: hourly to synoptic to seasonal. Using CO2 fluxes at varying temporal resolution from the SIB 2 and CASA biosphere models, we examine the model's ability to simulate CO2 variability in comparison to observations at different times, locations, and altitudes. We find that the model can resolve much of the variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The influence of key process representations is inferred. The high degree of fidelity in these simulations leads us to anticipate incorporation of realtime, highly resolved observations into a multiscale carbon cycle analysis system that will begin to bridge the gap between top-down and bottom-up flux estimation, which is a primary focus of NACP.

  4. Toward verifying fossil fuel CO2 emissions with the CMAQ model: motivation, model description and initial simulation.

    Science.gov (United States)

    Liu, Zhen; Bambha, Ray P; Pinto, Joseph P; Zeng, Tao; Boylan, Jim; Huang, Maoyi; Lei, Huimin; Zhao, Chun; Liu, Shishi; Mao, Jiafu; Schwalm, Christopher R; Shi, Xiaoying; Wei, Yaxing; Michelsen, Hope A

    2014-04-01

    Motivated by the question of whether and how a state-of-the-art regional chemical transport model (CTM) can facilitate characterization of CO2 spatiotemporal variability and verify CO2 fossil-fuel emissions, we for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate CO2. This paper presents methods, input data, and initial results for CO2 simulation using CMAQ over the contiguous United States in October 2007. Modeling experiments have been performed to understand the roles of fossil-fuel emissions, biosphere-atmosphere exchange, and meteorology in regulating the spatial distribution of CO2 near the surface over the contiguous United States. Three sets of net ecosystem exchange (NEE) fluxes were used as input to assess the impact of uncertainty of NEE on CO2 concentrations simulated by CMAQ. Observational data from six tall tower sites across the country were used to evaluate model performance. In particular, at the Boulder Atmospheric Observatory (BAO), a tall tower site that receives urban emissions from Denver CO, the CMAQ model using hourly varying, high-resolution CO2 fossil-fuel emissions from the Vulcan inventory and Carbon Tracker optimized NEE reproduced the observed diurnal profile of CO2 reasonably well but with a low bias in the early morning. The spatial distribution of CO2 was found to correlate with NO(x), SO2, and CO, because of their similar fossil-fuel emission sources and common transport processes. These initial results from CMAQ demonstrate the potential of using a regional CTM to help interpret CO2 observations and understand CO2 variability in space and time. The ability to simulate a full suite of air pollutants in CMAQ will also facilitate investigations of their use as tracers for CO2 source attribution. This work serves as a proof of concept and the foundation for more comprehensive examinations of CO2 spatiotemporal variability and various uncertainties in the future. Atmospheric CO2 has long been modeled

  5. High-performance modeling of CO2 sequestration by coupling reservoir simulation and molecular dynamics

    KAUST Repository

    Bao, Kai

    2013-01-01

    The present work describes a parallel computational framework for CO2 sequestration simulation by coupling reservoir simulation and molecular dynamics (MD) on massively parallel HPC systems. In this framework, a parallel reservoir simulator, Reservoir Simulation Toolbox (RST), solves the flow and transport equations that describe the subsurface flow behavior, while the molecular dynamics simulations are performed to provide the required physical parameters. Numerous technologies from different fields are employed to make this novel coupled system work efficiently. One of the major applications of the framework is the modeling of large scale CO2 sequestration for long-term storage in the subsurface geological formations, such as depleted reservoirs and deep saline aquifers, which has been proposed as one of the most attractive and practical solutions to reduce the CO2 emission problem to address the global-warming threat. To effectively solve such problems, fine grids and accurate prediction of the properties of fluid mixtures are essential for accuracy. In this work, the CO2 sequestration is presented as our first example to couple the reservoir simulation and molecular dynamics, while the framework can be extended naturally to the full multiphase multicomponent compositional flow simulation to handle more complicated physical process in the future. Accuracy and scalability analysis are performed on an IBM BlueGene/P and on an IBM BlueGene/Q, the latest IBM supercomputer. Results show good accuracy of our MD simulations compared with published data, and good scalability are observed with the massively parallel HPC systems. The performance and capacity of the proposed framework are well demonstrated with several experiments with hundreds of millions to a billion cells. To our best knowledge, the work represents the first attempt to couple the reservoir simulation and molecular simulation for large scale modeling. Due to the complexity of the subsurface systems

  6. Toward Verifying Fossil Fuel CO2 Emissions with the CMAQ Model: Motivation, Model Description and Initial Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhen; Bambha, Ray P.; Pinto, Joseph P.; Zeng, Tao; Boylan, Jim; Huang, Maoyi; Lei, Huimin; Zhao, Chun; Liu, Shishi; Mao, Jiafu; Schwalm, Christopher R.; Shi, Xiaoying; Wei, Yaxing; Michelsen, Hope A.

    2014-03-14

    Motivated by the urgent need for emission verification of CO2 and other greenhouse gases, we have developed regional CO2 simulation with CMAQ over the contiguous U.S. Model sensitivity experiments have been performed using three different sets of inputs for net ecosystem exchange (NEE) and two fossil fuel emission inventories, to understand the roles of fossil fuel emissions, atmosphere-biosphere exchange and transport in regulating the spatial and diurnal variability of CO2 near the surface, and to characterize the well-known ‘signal-to-noise’ problem, i.e. the interference from the biosphere on the interpretation of atmospheric CO2 observations. It is found that differences in the meteorological conditions for different urban areas strongly contribute to the contrast in concentrations. The uncertainty of NEE, as measured by the difference among the three different NEE inputs, has notable impact on regional distribution of CO2 simulated by CMAQ. Larger NEE uncertainty and impact are found over eastern U.S. urban areas than along the western coast. A comparison with tower CO2 measurements at Boulder Atmospheric Observatory (BAO) shows that the CMAQ model using hourly varied and high-resolution CO2 emission from the Vulcan inventory and CarbonTracker optimized NEE reasonably reproduce the observed diurnal profile, whereas switching to different NEE inputs significantly degrades the model performance. Spatial distribution of CO2 is found to correlate with NOx, SO2 and CO, due to their similarity in emission sources and transport processes. These initial results from CMAQ demonstrate the power of a state-of-the art CTM in helping interpret CO2 observations and verify fossil fuel emissions. The ability to simulate CO2 in CMAQ will also facilitate investigations of the utility of traditionally regulated pollutants and other species as tracers to CO2 source attribution.

  7. TransCom model simulations of hourly atmospheric CO2: Experimental overview and diurnal cycle results for 2002

    NARCIS (Netherlands)

    Law, R. M.; Peters, W.; Roedenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S. -J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-01-01

    [1] A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model

  8. TransCom model simulations of hourly atmospheric CO2: Experimental overview and diurnal cycle results for 2002

    NARCIS (Netherlands)

    Law, R. M.; Peters, W.; RöDenbeck, C.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Patra, P. K.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Takigawa, M.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-01-01

    A forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO2 and for SF6 and radon for 2000-2003. Twenty-five models or model

  9. Simulation and modeling CO2 absorption in biogas with DEA promoted K2CO3 solution in packed column

    Science.gov (United States)

    Nurkhamidah, Siti; Altway, Ali; Airlangga, Bramantyo; Emilia, Dwi Putri

    2017-05-01

    Absorption of carbon dioxide (CO2) using potassium carbonate (K2CO3) is one of biogas purification method. However, K2CO3 have slow mass transfer in liquid phase. So it is necessary to eliminate the disadvantage of CO2 absorption using K2CO3 by adding promotor (activator). Diethanol amine (DEA) is one of promotor which can increase its reaction rate. Simulation and modeling research of the CO2 absorption from biogas with DEA promoted K2CO3 solution has not been conducted. Thus, the main goal of this research is create model and simulation for the CO2 absorption from biogas with DEA promoted K2CO3 solution, then observe the influence of promoter concentration. DEA concentration varies between 1-5 %wt. From the simulation, we concluded that the CO2 removal rise with the increasing of promoter concentration. The highest CO2 removal is 54.5318 % at 5 % wt DEA concentration.

  10. A mechanistic diagnosis of the simulation of soil CO2 efflux of the ACME Land Model

    Science.gov (United States)

    Liang, J.; Ricciuto, D. M.; Wang, G.; Gu, L.; Hanson, P. J.; Mayes, M. A.

    2017-12-01

    Accurate simulation of the CO2 efflux from soils (i.e., soil respiration) to the atmosphere is critical to project global biogeochemical cycles and the magnitude of climate change in Earth system models (ESMs). Currently, the simulated soil respiration by ESMs still have a large uncertainty. In this study, a mechanistic diagnosis of soil respiration in the Accelerated Climate Model for Energy (ACME) Land Model (ALM) was conducted using long-term observations at the Missouri Ozark AmeriFlux (MOFLUX) forest site in the central U.S. The results showed that the ALM default run significantly underestimated annual soil respiration and gross primary production (GPP), while incorrectly estimating soil water potential. Improved simulations of soil water potential with site-specific data significantly improved the modeled annual soil respiration, primarily because annual GPP was simultaneously improved. Therefore, accurate simulations of soil water potential must be carefully calibrated in ESMs. Despite improved annual soil respiration, the ALM continued to underestimate soil respiration during peak growing seasons, and to overestimate soil respiration during non-peak growing seasons. Simulations involving increased GPP during peak growing seasons increased soil respiration, while neither improved plant phenology nor increased temperature sensitivity affected the simulation of soil respiration during non-peak growing seasons. One potential reason for the overestimation of the soil respiration during non-peak growing seasons may be that the current model structure is substrate-limited, while microbial dormancy under stress may cause the system to become decomposer-limited. Further studies with more microbial data are required to provide adequate representation of soil respiration and to understand the underlying reasons for inaccurate model simulations.

  11. Simulation of spring wheat responses to elevated CO2 and temperature by using CERES-wheat crop model

    Directory of Open Access Journals (Sweden)

    H. LAURILA

    2008-12-01

    Full Text Available The CERES-wheat crop simulation model was used to estimate the changes in phenological development and yield production of spring wheat (Triticum aestivum L., cv. Polkka under different temperature and CO2 growing conditions. The effects of elevated temperature (3-4°C and CO2 concentration (700 ppm as expected for Finland in 2100 were simulated. The model was calibrated for long-day growing conditions in Finland. The CERES-wheat genetic coefficients for cv. Polkka were calibrated by using the MTT Agrifood Research Finland (MTT official variety trial data (1985-1990. Crop phenological development and yield measurements from open-top chamber experiments with ambient and elevated temperature and CO2 treatments were used to validate the model. Simulated mean grain yield under ambient temperature and CO2 conditions was 6.16 t ha-1 for potential growth (4.49 t ha-1 non-potential and 5.47 t ha-1 for the observed average yield (1992-1994 in ambient open-top chamber conditions. The simulated potential grain yield increased under elevated CO2 (700 ppm to 142% (167% non-potential from the simulated reference yield (100%, ambient temperature and CO2 350 ppm. Simulations for current sowing date and elevated temperature (3°C indicate accelerated anthesis and full maturity. According to the model estimations, potential yield decreased on average to 80.4% (76.8% non-potential due to temperature increase from the simulated reference. When modelling the concurrent elevated temperature and CO2 interaction, the increase in grain yield due to elevated CO2 was reduced by the elevated temperature. The combined CO2 and temperature effect increased the grain yield to 106% for potential growth (122% non-potential compared to the reference. Simulating the effects of earlier sowing, the potential grain yield increased under elevated temperature and CO2 conditions to 178% (15 days earlier sowing from 15 May, 700 ppm CO2, 3°C from the reference. Simulation results suggest

  12. Molecular simulation and mathematical modelling of glass transition temperature depression induced by CO2 plasticization in Polysulfone membranes

    Science.gov (United States)

    Lock, S. S. M.; Lau, K. K.; Lock Sow Mei, Irene; Shariff, A. M.; Yeong, Y. F.; Bustam, A. M.

    2017-08-01

    A sequence of molecular modelling procedure has been proposed to simulate experimentally validated membrane structure characterizing the effect of CO2 plasticization, whereby it can be subsequently employed to elucidate the depression in glass transition temperature (Tg ). Based on the above motivation, unswollen and swollen Polysulfone membrane structures with different CO2 loadings have been constructed, whereby the accuracy has been validated through good compliance with experimentally measured physical properties. It is found that the presence of CO2 constitutes to enhancement in polymeric chain relaxation, which consequently promotes the enlargement of molecular spacing and causes dilation in the membrane matrix. A series of glass transition temperature treatment has been conducted on the verified molecular structure to elucidate the effect of CO2 loadings to the depression in Tg induced by plasticization. Subsequently, a modified Michealis-Menten (M-M) function has been implemented to quantify the effect of CO2 loading attributed to plasticization towards Tg .

  13. Late Cretaceous climate simulations with different CO2 levels and subarctic gateway configurations: A model-data comparison

    Science.gov (United States)

    Niezgodzki, Igor; Knorr, Gregor; Lohmann, Gerrit; Tyszka, Jarosław; Markwick, Paul J.

    2017-09-01

    We investigate the impact of different CO2 levels and different subarctic gateway configurations on the surface temperatures during the latest Cretaceous using the Earth System Model COSMOS. The simulated temperatures are compared with the surface temperature reconstructions based on a recent compilation of the latest Cretaceous proxies. In our numerical experiments, the CO2 level ranges from 1 to 6 times the preindustrial (PI) CO2 level of 280 ppm. On a global scale, the most reasonable match between modeling and proxy data is obtained for the experiments with 3 to 5 × PI CO2 concentrations. However, the simulated low- (high-) latitude temperatures are too high (low) as compared to the proxy data. The moderate CO2 levels scenarios might be more realistic, if we take into account proxy data and the dead zone effect criterion. Furthermore, we test if the model-data discrepancies can be caused by too simplistic proxy-data interpretations. This is distinctly seen at high latitudes, where most proxies are biased toward summer temperatures. Additional sensitivity experiments with different ocean gateway configurations and constant CO2 level indicate only minor surface temperatures changes (greenhouse worlds is best constrained by temperatures in the midlatitudes.

  14. Effects of elevated CO2 and drought on wheat : testing crop simulation models for different experimental and climatic conditions

    NARCIS (Netherlands)

    Ewert, F.; Rodriguez, D.; Jamieson, P.; Semenov, M.A.; Mitchell, R.A.C.; Goudriaan, J.; Porter, J.R.; Kimball, B.A.; Pinter, P.J.; Manderscheid, R.; Weigel, H.J.; Fangmeier, A.; Fereres, E.; Villalobos, F.

    2002-01-01

    Effects of increasing carbon dioxide concentration [CO2] on wheat vary depending on water supply and climatic conditions, which are difficult to estimate. Crop simulation models are often used to predict the impact of global atmospheric changes on food production. However, models have rarely been

  15. Improving ecophysiological simulation models to predict the impact of elevated atmospheric CO(2) concentration on crop productivity.

    Science.gov (United States)

    Yin, Xinyou

    2013-08-01

    Process-based ecophysiological crop models are pivotal in assessing responses of crop productivity and designing strategies of adaptation to climate change. Most existing crop models generally over-estimate the effect of elevated atmospheric [CO2], despite decades of experimental research on crop growth response to [CO2]. A review of the literature indicates that the quantitative relationships for a number of traits, once expressed as a function of internal plant nitrogen status, are altered little by the elevated [CO2]. A model incorporating these nitrogen-based functional relationships and mechanisms simulated photosynthetic acclimation to elevated [CO2], thereby reducing the chance of over-estimating crop response to [CO2]. Robust crop models to have small parameterization requirements and yet generate phenotypic plasticity under changing environmental conditions need to capture the carbon-nitrogen interactions during crop growth. The performance of the improved models depends little on the type of the experimental facilities used to obtain data for parameterization, and allows accurate projections of the impact of elevated [CO2] and other climatic variables on crop productivity.

  16. Modeling of CO2 storage in aquifers

    International Nuclear Information System (INIS)

    Savioli, Gabriela B; Santos, Juan E

    2011-01-01

    Storage of CO 2 in geological formations is a means of mitigating the greenhouse effect. Saline aquifers are a good alternative as storage sites due to their large volume and their common occurrence in nature. The first commercial CO 2 injection project is that of the Sleipner field in the Utsira Sand aquifer (North Sea). Nevertheless, very little was known about the effectiveness of CO 2 sequestration over very long periods of time. In this way, numerical modeling of CO 2 injection and seismic monitoring is an important tool to understand the behavior of CO 2 after injection and to make long term predictions in order to prevent CO 2 leaks from the storage into the atmosphere. The description of CO 2 injection into subsurface formations requires an accurate fluid-flow model. To simulate the simultaneous flow of brine and CO 2 we apply the Black-Oil formulation for two phase flow in porous media, which uses the PVT data as a simplified thermodynamic model. Seismic monitoring is modeled using Biot's equations of motion describing wave propagation in fluid-saturated poroviscoelastic solids. Numerical examples of CO 2 injection and time-lapse seismics using data of the Utsira formation show the capability of this methodology to monitor the migration and dispersal of CO 2 after injection.

  17. 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.

  18. Column-averaged CO2 concentrations in the subarctic from GOSAT retrievals and NIES transport model simulations

    Science.gov (United States)

    Belikov, D. A.; Bril, A.; Maksyutov, S.; Oshchepkov, S.; Saeki, T.; Takagi, H.; Yoshida, Y.; Ganshin, A.; Zhuravlev, R.; Aoki, S.; Yokota, T.

    2014-06-01

    The distribution of atmospheric carbon dioxide (CO2) in the subarctic was investigated using the National Institute for Environmental Studies (NIES) three-dimensional transport model (TM) and retrievals from the Greenhouse gases Observing SATellite (GOSAT). Column-averaged dry air mole fractions of subarctic atmospheric CO2 (XCO2) from the NIES TM for four flux combinations were analyzed. Two flux datasets were optimized using only surface observations and two others were optimized using both surface and GOSAT Level 2 data. Two inverse modeling approaches using GOSAT data were compared. In the basic approach adopted in the GOSAT Level 4 product, the GOSAT observations are aggregated into monthly means over 5° × 5° grids. In the alternative method, the model-observation misfit is estimated for each observation separately. The XCO2 values simulated with optimized fluxes were validated against Total Carbon Column Observing Network (TCCON) ground-based high-resolution Fourier Transform Spectrometer (FTS) measurements. Optimized fluxes were applied to study XCO2 seasonal variability over the period 2009-2010 in the Arctic and subarctic regions. The impact on CO2 levels of emissions from enhancement of biospheric respiration induced by the high temperature and strong wildfires occurring in the summer of 2010 was analyzed. Use of GOSAT data has a substantial impact on estimates of the level of CO2 interanual variability.

  19. Model Simulations of the Competing Climatic Effects of SO2 and CO2.

    Science.gov (United States)

    Kaufman, Yoram J.; Chou, Ming-Dah

    1993-07-01

    Sulfur dioxide-derived cloud condensation nuclei are expected to enhance the planetary albedo, thereby cooling the planet. This effect might counteract the global warming expected from enhanced greenhouse gases. A detailed treatment of the relationship between fossil fuel burning and the SO2 effect on cloud albedo is implemented in a two-dimensional model for assessing the climate impact. Although there are large gaps in our knowledge of the atmospheric sources and sinks of sulfate aerosol, it is possible to reach some general conclusions. Using a conservative approach, results show that the cooling induced by the SO2 emission can presently counteract 50% of the CO2 greenhouse warming. Since 1980, a strong warming trend has been predicted by the model, 0.15°C, during the 1980-1990 period alone. The model predicts that by the year 2060 the SO2 cooling reduces climate warming by 0.5°C or 25% for the Intergovernmental Panel on Climate Change (IPCC) business as usual (BAU) scenario and 0.2°C or 20% for scenario D (for a slow pace of fossil fuel burning). The hypothesis is examined that the different responses between the Northern Hemisphere (NH) and the Southern Hemisphere (SH) can be used to validate the presence of the SO2-induced cooling. Despite the fact that most of the SO2-induced cooling takes place in the Northern Hemispheric continents, the model-predicted difference in the temperature response between the NH and the SH of 0.2°C in 1980 is expected to remain about the same at least until 2060. This result is a combined effect of the much faster response of the continents than the oceans and of the larger forcing due to CO2 than due to the SO2. The climatic response to a complete filtering of SO2 from the emission products in order to reduce acid rain is also examined. The result is a warming surge of 0.4°C in the first few years after the elimination of the SO2 emission.

  20. Modeling solubility of CO2/hydrocarbon gas in ionic liquid ([emim][FAP]) using Aspen Plus simulations.

    Science.gov (United States)

    Bagchi, Bishwadeep; Sati, Sushmita; Shilapuram, Vidyasagar

    2017-08-01

    The Peng-Robinson equation of state with quadratic van der Waals (vdW) mixing rule model was chosen to perform the thermodynamic calculations in Flash3 column of Aspen Plus to predict the solubility of CO 2 or any one of the hydrocarbons (HCs) among methane, ethane, propane, and butane in an ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([emim][FAP]). Bubble point pressure, solubility, bubble point temperature, fugacity, and partial molar volume at infinite dilution were obtained from the simulations, and enthalpy of absorption, Gibbs free energy of solvation, and entropy change of absorption were estimated by thermodynamic relations. Results show that carbon chain length has a significant effect on the bubble point pressure. Methane has the highest bubble point pressure among all the considered HCs and CO 2 . The bubble point pressure and fugacity variation with temperature is different for CO 2 as compared to HCs for mole fractions above 0.2. Two different profiles are noticed for enthalpy of absorption when plotted as a function of mole fraction of gas soluble in IL. Partial molar volume of CO 2 decreases with increase in temperature in [emim][FAP], while it is increased for HCs. Bubble point temperature decreases with increase in the mole fraction of the solute. Entropy of solvation increases with temperature till a particular value followed by a decrease with further increase in temperature. Gibbs free energy change of solvation showed that the process of solubility was spontaneous.

  1. Computer Simulation and Modeling of CO2 Removal Systems for Exploration 2013-2014

    Science.gov (United States)

    Coker, R.; Knox, J.; Gomez, C.

    2015-01-01

    The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project and the follow-on Life Support Systems (LSS) project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper will describes the testing and 1-D modeling of the combined water desiccant and carbon dioxide sorbent subsystems of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development.

  2. Results from a 2 x CO2 simulation with the Canadian Climate Centre general circulation model

    International Nuclear Information System (INIS)

    Boer, G.J.

    1990-01-01

    The Canadian Climate Centre's general circulation model (GCM), GCMII, was used to simulate a doubling of atmospheric carbon dioxide concentration. The experiment was a standard greenhouse gas climate change study, using a three-dimensional atmospheric circulation model coupled to a simple 'slab' ocean and a thermodynamic ice model. This standard experiment retains the sophistication and generality of an atmospheric GCM, is straightforward in its use of simplified ocean and ice models, is comparatively economical of computer time, and permits comparison of results from different models. Features of the second generation GCMII include: higher resolution at T32L10 with a transform grid of 3.75 x 3.75 degree; full diurnal and annual cycles; ocean and sea ice treatment involving specification of ocean transports; modified treatment of land surface processes and hydrology; a parameterization of cloud optical feedback; and a retention of the special application data sets of surface parameters for North America and Europe. Results of the simulation were a globally averaged surface temperature increase of 3.5 degree C; a precipitation and evaporation increase of 3%; an average decrease in soil moisture of 6.6%; a decrease in cloud cover of 2.2%; a 66% decrease in mass of sea ice; and marked changes in other quantities in the polar region. 2 refs., 2 figs., 2 tabs

  3. Advanced modeling and simulation of integrated gasification combined cycle power plants with CO2-capture

    International Nuclear Information System (INIS)

    Rieger, Mathias

    2014-01-01

    The objective of this thesis is to provide an extensive description of the correlations in some of the most crucial sub-processes for hard coal fired IGCC with carbon capture (CC-IGCC). For this purpose, process simulation models are developed for four industrial gasification processes, the CO-shift cycle, the acid gas removal unit, the sulfur recovery process, the gas turbine, the water-/steam cycle and the air separation unit (ASU). Process simulations clarify the influence of certain boundary conditions on plant operation, performance and economics. Based on that, a comparative benchmark of CC-IGCC concepts is conducted. Furthermore, the influence of integration between the gas turbine and the ASU is analyzed in detail. The generated findings are used to develop an advanced plant configuration with improved economics. Nevertheless, IGCC power plants with carbon capture are not found to be an economically efficient power generation technology at present day boundary conditions.

  4. Responses to atmospheric CO2concentrations in crop simulation models: a review of current simple and semicomplex representations and options for model development.

    Science.gov (United States)

    Vanuytrecht, Eline; Thorburn, Peter J

    2017-05-01

    Elevated atmospheric CO 2 concentrations ([CO 2 ]) cause direct changes in crop physiological processes (e.g. photosynthesis and stomatal conductance). To represent these CO 2 responses, commonly used crop simulation models have been amended, using simple and semicomplex representations of the processes involved. Yet, there is no standard approach to and often poor documentation of these developments. This study used a bottom-up approach (starting with the APSIM framework as case study) to evaluate modelled responses in a consortium of commonly used crop models and illuminate whether variation in responses reflects true uncertainty in our understanding compared to arbitrary choices of model developers. Diversity in simulated CO 2 responses and limited validation were common among models, both within the APSIM framework and more generally. Whereas production responses show some consistency up to moderately high [CO 2 ] (around 700 ppm), transpiration and stomatal responses vary more widely in nature and magnitude (e.g. a decrease in stomatal conductance varying between 35% and 90% among models was found for [CO 2 ] doubling to 700 ppm). Most notably, nitrogen responses were found to be included in few crop models despite being commonly observed and critical for the simulation of photosynthetic acclimation, crop nutritional quality and carbon allocation. We suggest harmonization and consideration of more mechanistic concepts in particular subroutines, for example, for the simulation of N dynamics, as a way to improve our predictive understanding of CO 2 responses and capture secondary processes. Intercomparison studies could assist in this aim, provided that they go beyond simple output comparison and explicitly identify the representations and assumptions that are causal for intermodel differences. Additionally, validation and proper documentation of the representation of CO 2 responses within models should be prioritized. © 2017 John Wiley & Sons Ltd.

  5. Mass Conservation in a Chemical Transport Model and its Effect on CO2 and SF6 Simulations

    Science.gov (United States)

    Zhu, Z.; Weaver, C.; Kawa, S. R.; Douglass, A. R.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Chemical transport models (CTMs) must conserve mass to be useful for applications involving assessment of the effect of various pollutants on the troposphere and stratosphere. Furthermore, calculations of the evolution of constituents such as SF6 are used to evaluate overall model transport, and interpretation of such simulations is clouded if mass conservation is not assured. For realistic simulations or predictions, it is crucial that constituents are not produced or lost by transport or other processes in the CTMs. Analysis of CO2 and SF6 experiments using a CTM shows that problems with mass conservation can seriously degrade the simulations. Failure to conserve mass results from inconsistency of the surface pressure tendency and the divergence of horizontal mass flux when the model is forced by assimilated meteorological data. We have developed an effective method to eliminate the inconsistency by modifying the divergent part of the wind field. The changes in the wind fields are quite small but the impact on mass conservation is large. Parameterizations of physical processes such as convection or turbulent transport can also affect mass conservation. The lack of conservation is small but accumulates when integrations are lengthy such as required for SF6. This lack of conservation is found using winds from either a GCM or from an assimilation system. A simple adjustment removes much of the inaccuracy in the convective parameterization. A CO2 simulation using assimilated winds from the most recent version of the Goddard Earth Observing System Data Assimilation System will be used to illustrate the impact of these transport improvements.

  6. Modeling CO2 Gas Migration of Shallow Subsurface CO2 Leakage Experiments

    Science.gov (United States)

    Porter, M. L.; Plampin, M. R.; Pawar, R.; Illangasekare, T. H.

    2013-12-01

    Leakage of injected CO2 into shallow subsurface aquifers or back into the atmosphere at geologic carbon sequestration sites is a risk that must be minimized. One potential CO2 leakage pathway involves the transport of dissolved CO2 into a shallow aquifer where the CO2 exsolves, forming a free CO2 gas phase that subsequently migrates through the aquifer. In order to reduce the negative effects of CO2 exsolution, it is important to fully understand each of the processes controlling the movement CO2, as well as the effects of aquifer heterogeneity on the overall fate and transport of CO2. In this work, we present multiphase flow simulations of intermediate scale CO2 exsolution experiments. The multiphase flow simulations were carried out using the Finite Element Heat and Mass Transfer code (FEHM) developed at Los Alamos National Laboratory. Simulations were first designed to model experiments conducted in two different homogeneous packed sands. PEST (Parameter Estimation and Uncertainty Analysis) was used to optimize multiphase flow parameters (i.e., porosity, permeability, relative permeability, and capillary pressure) within FEHM. The optimized parameters were subsequently used to model heterogeneous experiments consisting of various packing configurations using the same sands. Comparisons of CO2 saturation between experiments and simulations will be presented and analyzed.

  7. Demonstrating full-scale post-combustion CO2 capture for coal-fired power plants through dynamic modelling and simulation

    OpenAIRE

    Lawal, Adekola; Wang, Meihong; Stephenson, Peter; Obi, Okwose

    2012-01-01

    This study aims to provide insights into the design and operation of full-scale post-combustion CO2 capture for a 500MWe sub-critical power plant through dynamic modelling and simulation. The development and validation of the dynamic models of the power plant and CO2 capture plant are described. In addition, the scale-up of the CO2 capture plant from pilot plant scale (where it was validated) to full scale is discussed. Subsequently the manner in which the two plant models were linked is disc...

  8. Modelling and numerical simulation of Supercritical CO2 debinding of Inconel 718 components elaborated by Metal Injection Molding

    Directory of Open Access Journals (Sweden)

    Aboubakry Agne

    2017-10-01

    Full Text Available A debinding step using the supercritical state of a fluid has been increasingly investigated for extracting organic binders from components obtained by metal-injection molding. It consists of placing the component in an enclosure subjected to pressure and temperatures higher than the critical point to perform polymer extraction of the Metal-injection molding (MIM component. It is an alternative to conventional solvent debinding. The topic of this study is to model and simulate the supercritical debinding stage to elucidate the mechanism of polymer degradation and stabilization with a three-dimensional model. Modelling this extraction process would optimize the process on an industrial scale. It can be physically described by Fick’s law of diffusion. The model’s main parameter is the diffusion coefficient, which is identified by using linear regression based on the least-squares method. In the model, an effective length scale is specially developed to take into account the diffusion in all directions. The tests were performed for extracting polyethylene glycol, an organic additive, using supercritical CO2 in injected components. The feedstock is composed of polypropylene, polyethylene glycol, and stearic-acid as binder mixed with Inconel 718 super-alloy powders. The identified parameters were used to calculate the diffusion coefficient and simulate the supercritical debinding step on the Comsol Multiphysics® finite-element software platform to predict the remaining binder. The obtained numerical simulation results are in good agreement with the experimental data. The proposed numerical simulations allow for the determination of the remaining polyethylene glycol (PEG binder distribution with respect to processing parameters for components during the supercritical debinding process at any time. Moreover, this approach can be used in other formulation, powder, and binder systems.

  9. A Case Study on Observed and Simulated CO2 Concentration Profiles in Hefei based on Raman Lidar and GEOS-Chem Model

    Directory of Open Access Journals (Sweden)

    Wang Yinan

    2016-01-01

    Full Text Available Observations of atmospheric CO2 concentration profiles provide significative constraints on the global/regional inversions of carbon sources and sinks. Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences developed a Raman Lidar system to detect the vertical distribution of atmospheric CO2. This paper compared the observations with the modeled results from a three-dimensional global chemistry transport model-GEOS-Chem, which showed a good agreement in the trend of change with lidar measurements. The case study indicated a potential for better simulating vertical distribution of atmospheric CO2 by combining with lidar measurements.

  10. Modeling and Simulation of CO2 Absorption into Promoted Aqueous Potassium Carbonate Solution in Industrial Scale Packed Column

    Directory of Open Access Journals (Sweden)

    Ali Altway

    2015-01-01

    Full Text Available This paper aims to develop mathematical model for investigating the CO2 absorption into promoted hot potassium carbonate solution in industrial scale packed column. The absorber is used in a large-scale ammonia plant to remove CO2 from the process gas stream. The CO2 is removed from the gas stream by counter-current absorption in two stages column. Lean solution and semi lean solution were fed into the top of upper part column and lower part column, respectively. To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory is considered. The heat effects are taken into account. The model consists of differential mass and heat balance and considers the interactions between mass-transfer and chemical kinetics using enhancement factor concept. The chemical reaction in the liquid phase is based on the bicarbonate ion formation from CO2 as the rate-determining step. Gas solubility, mass and heat transfer coefficients, reaction kinetics and equilibrium were estimated using correlations from literatures.Therefore, multi-component absorption phenomena were considered in the mathematical model. The model was validated using plant data and was used to compute temperature and concentration profiles in the absorber. The variation in percent CO2 recovery with respect to changes in some operating variables is evaluated. The effect of various kinds of promoters added into potassium carbonate solution on the carbon dioxide recovery was also investigated.

  11. Kinetics of CO2 diffusion in human carbonic anhydrase: a study using molecular dynamics simulations and the Markov-state model.

    Science.gov (United States)

    Chen, Gong; Kong, Xian; Lu, Diannan; Wu, Jianzhong; Liu, Zheng

    2017-05-10

    Molecular dynamics (MD) simulations, in combination with the Markov-state model (MSM), were applied to probe CO 2 diffusion from an aqueous solution into the active site of human carbonic anhydrase II (hCA-II), an enzyme useful for enhanced CO 2 capture and utilization. The diffusion process in the hydrophobic pocket of hCA-II was illustrated in terms of a two-dimensional free-energy landscape. We found that CO 2 diffusion in hCA-II is a rate-limiting step in the CO 2 diffusion-binding-reaction process. The equilibrium distribution of CO 2 shows its preferential accumulation within a hydrophobic domain in the protein core region. An analysis of the committors and reactive fluxes indicates that the main pathway for CO 2 diffusion into the active site of hCA-II is through a binding pocket where residue Gln 136 contributes to the maximal flux. The simulation results offer a new perspective on the CO 2 hydration kinetics and useful insights toward the development of novel biochemical processes for more efficient CO 2 sequestration and utilization.

  12. Molecular simulations of CO2 at interfaces

    DEFF Research Database (Denmark)

    Silvestri, Alessandro

    . DFT has some advantages over MD in terms of computational cost but MD allows exploration of larger and more complex systems. Dierent options for geologic storage of CO2 have been proposed. Carbonate minerals are ubiquitous, limestone, chalk and marble constitute a signicant fraction of the sedimentary...... rock record and the formations are generally porous so their probable response to CO2 sequestration needs to be investigated. However, despite the large number of geologic sequestration publications on water{rock interactions over the last decade, studies on carbonate reservoirs remain scarce....... Carbonate reservoirs are being considered as CO2 storage sites so more information is needed, for providing data for safety assessment models and for fundamental understanding of the relevant processes and their in uence. Theoretical approaches for the carbonate minerals are even more scarce and only few...

  13. An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

    KAUST Repository

    Kong, X.

    2012-11-03

    The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

  14. How Accurately Do Maize Crop Models Simulate the Interactions of Atmospheric CO2 Concentration Levels With Limited Water Supply on Water Use and Yield?

    Science.gov (United States)

    Durand, Jean-Louis; Delusca, Kenel; Boote, Ken; Lizaso, Jon; Manderscheid, Remy; Weigel, Hans Johachim; Ruane, Alexander Clark; Rosenzweig, Cynthia E.; Jones, Jim; Ahuja, Laj; hide

    2017-01-01

    This study assesses the ability of 21 crop models to capture the impact of elevated CO2 concentration [CO2] on maize yield and water use as measured in a 2-year Free Air Carbon dioxide Enrichment experiment conducted at the Thunen Institute in Braunschweig, Germany (Manderscheid et al. 2014). Data for ambient [CO2] and irrigated treatments were provided to the 21 models for calibrating plant traits, including weather, soil and management data as well as yield, grain number, above ground biomass, leaf area index, nitrogen concentration in biomass and grain, water use and soil water content. Models differed in their representation of carbon assimilation and evapotranspiration processes. The models reproduced the absence of yield response to elevated [CO2] under well-watered conditions, as well as the impact of water deficit at ambient [CO2], with 50 percent of models within a range of plus/minus 1 Mg ha(exp. -1) around the mean. The bias of the median of the 21 models was less than 1 Mg ha(exp. -1). However under water deficit in one of the two years, the models captured only 30 percent of the exceptionally high [CO2] enhancement on yield observed. Furthermore the ensemble of models was unable to simulate the very low soil water content at anthesis and the increase of soil water and grain number brought about by the elevated [CO2] under dry conditions. Overall, we found models with explicit stomatal control on transpiration tended to perform better. Our results highlight the need for model improvement with respect to simulating transpirational water use and its impact on water status during the kernel-set phase.

  15. Influence of Increased CO2 on Regional Climate Simulations

    Science.gov (United States)

    Han, J.; Roads, J. O.

    2001-12-01

    Several PCM (Parallel Climate Model) coupled (atmosphere-ocean) simulations have been developed starting from a period back in the 1800s through 2095, using historical CO2 concentrations for the past and "business-as-usual" CO2 concentrations for the future. What differences occur if these global low-resolution (T42L18) simulations are down-scaled with a regional climate model? Toward this goal, three basic numerical simulations with the regional spectral model (RSM) at a spatial resolution of about 50 km are being conducted to investigate regional US responses. Both the NCEP Reanalysis II (T62L28) and the PCM simulation (T42L18) data are used as initial and boundary conditions for present-day conditions (1986-present). The observed sea surface temperature (SST) is used in the RSM-reanalysis run while in the RSM-PCM run, the SST is given by the global simulation. The other surface fields in both runs are given by the climatological data. Initial comparisons indicate that the RSM simulations preserve the larger scale features of the reanalysis and PCM simulation, while providing more realistic smaller scale features not present in the driving large-scale fields. The years of 2040-2060 with the increased CO2 found in the PCM simulations are chosen for the period of increased CO2. Several additional ensemble PCM members will be used as boundary conditions in order to assess uncertainty at regional scales from both the global PCM and regional RSM.

  16. Constraining a complex biogeochemical model for CO2 and N2O emission simulations from various land uses by model-data fusion

    Science.gov (United States)

    Houska, Tobias; Kraus, David; Kiese, Ralf; Breuer, Lutz

    2017-07-01

    This study presents the results of a combined measurement and modelling strategy to analyse N2O and CO2 emissions from adjacent arable land, forest and grassland sites in Hesse, Germany. The measured emissions reveal seasonal patterns and management effects, including fertilizer application, tillage, harvest and grazing. The measured annual N2O fluxes are 4.5, 0.4 and 0.1 kg N ha-1 a-1, and the CO2 fluxes are 20.0, 12.2 and 3.0 t C ha-1 a-1 for the arable land, grassland and forest sites, respectively. An innovative model-data fusion concept based on a multicriteria evaluation (soil moisture at different depths, yield, CO2 and N2O emissions) is used to rigorously test the style="" class="text">LandscapeDNDC biogeochemical model. The model is run in a Latin-hypercube-based uncertainty analysis framework to constrain model parameter uncertainty and derive behavioural model runs. The results indicate that the model is generally capable of predicting trace gas emissions, as evaluated with RMSE as the objective function. The model shows a reasonable performance in simulating the ecosystem C and N balances. The model-data fusion concept helps to detect remaining model errors, such as missing (e.g. freeze-thaw cycling) or incomplete model processes (e.g. respiration rates after harvest). This concept further elucidates the identification of missing model input sources (e.g. the uptake of N through shallow groundwater on grassland during the vegetation period) and uncertainty in the measured validation data (e.g. forest N2O emissions in winter months). Guidance is provided to improve the model structure and field measurements to further advance landscape-scale model predictions.

  17. 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

  18. Multi-millennia simulation of Greenland deglaciation from the Max-Plank-Institute Model (MPI-ISM) 2xCO2 simulation

    Science.gov (United States)

    Cabot, Vincent; Vizcaino, Miren; Mikolajewicz, Uwe

    2016-04-01

    Long-term ice sheet and climate coupled simulations are of great interest since they assess how the Greenland Ice Sheet (GrIS) will respond to global warming and how GrIS changes will impact on the climate system. We have run the Max-Plank-Institute Earth System Model coupled with an Ice Sheet Model (SICOPOLIS) over a time period of 10500 years under two times CO2 forcing. This is a coupled atmosphere (ECHAM5T31), ocean (MPI-OM), dynamic vegetation (LPJ), and ice sheet (SICOPOLIS, 10 km horizontal resolution) model. Given the multi-millennia simulation, the horizontal spatial resolution of the atmospheric component is relatively coarse (3.75°). A time-saving technique (asynchronous coupling) is used once the global climate reaches quasi-equilibrium. In our doubling-CO2 simulation, the GrIS is expected to break up into two pieces (one ice cap in the far north on one ice sheet in the south and east) after 3000 years. During the first 500 simulation years, the GrIS climate and surface mass balance (SMB) are mainly affected by the greenhouse effect-forced climate change. After the simulated year 500, the global climate reaches quasi-equilibrium. Henceforth Greenland climate change is mainly due to ice sheet decay. GrIS albedo reduction enhances melt and acts as a powerful feedback for deglaciation. Due to increased cloudiness in the Arctic region as a result of global climate change, summer incoming shortwave radiation is substantially reduced over Greenland, reducing deglaciation rates. At the end of the simulation, Greenland becomes green with forest growing over the newly deglaciated regions. References: Helsen, M. M., van de Berg, W. J., van de Wal, R. S. W., van den Broeke, M. R., and Oerlemans, J. (2013), Coupled regional climate-ice-sheet simulation shows limited Greenland ice loss during the Eemian, Climate of the Past, 9, 1773-1788, doi: 10.5194/cp-9-1773-2013 Helsen, M. M., van de Wal, R. S. W., van den Broeke, M. R., van de Berg, W. J., and Oerlemans, J

  19. A phase-field lattice Boltzmann model for simulating multiphase flows in porous media: Application and comparison to experiments of CO2 sequestration at pore scale

    Science.gov (United States)

    Fakhari, Abbas; Li, Yaofa; Bolster, Diogo; Christensen, Kenneth T.

    2018-04-01

    We implement a phase-field based lattice-Boltzmann (LB) method for numerical simulation of multiphase flows in heterogeneous porous media at pore scales with wettability effects. The present method can handle large density and viscosity ratios, pertinent to many practical problems. As a practical application, we study multiphase flow in a micromodel representative of CO2 invading a water-saturated porous medium at reservoir conditions, both numerically and experimentally. We focus on two flow cases with (i) a crossover from capillary fingering to viscous fingering at a relatively small capillary number, and (ii) viscous fingering at a relatively moderate capillary number. Qualitative and quantitative comparisons are made between numerical results and experimental data for temporal and spatial CO2 saturation profiles, and good agreement is found. In particular, a correlation analysis shows that any differences between simulations and results are comparable to intra-experimental differences from replicate experiments. A key conclusion of this work is that system behavior is highly sensitive to boundary conditions, particularly inlet and outlet ones. We finish with a discussion on small-scale flow features, such as the emergence of strong recirculation zones as well as flow in which the residual phase is trapped, including a close look at the detailed formation of a water cone. Overall, the proposed model yields useful information, such as the spatiotemporal evolution of the CO2 front and instantaneous velocity fields, which are valuable for understanding the mechanisms of CO2 infiltration at the pore scale.

  20. Simulation with models of increasing complexity of CO2 emissions and nitrogen mineralisation, after soil application of labelled pig slurry and maize stalks

    Science.gov (United States)

    Bechini, Luca; Marino Gallina, Pietro; Geromel, Gabriele; Corti, Martina; Cavalli, Daniele

    2015-04-01

    High amounts of nitrogen are available per unit area in regions with intensive livestock operations. In swine farms, pig slurries are frequently incorporated in the soil together with maize stalks. Simulation models may help to understand nitrogen dynamics associated with animal manure and crop residue decomposition in the soil, and to support the definition of best management practices. The objective of this work was to test the ability of different models to simulate CO2 emissions and nitrogen mineralisation during a laboratory incubation (under optimal soil water content and constant temperature) of maize stalks (ST) and pig slurry (PS). A loam soil was amended with labelled (15N) or unlabelled maize stalks and pig slurries, in the presence of ammonium sulphate (AS). These treatments were established: unfertilised soil; ST15 + AS + PS; ST + AS15 + PS; and ST + AS + PS15. During 180 days, we measured CO2 emissions; microbial biomass C, N, and 15N; and soil mineral N (SMN and SM-15N). Three models of increasing complexity were calibrated using measured data. The models were two modifications of ICBM 2B/N (Kätterer and Andrén, 2001) and CN-SIM (Petersen et al., 2005). The three models simulated rather accurately the emissions of CO2 throughout the incubation period (Relative Root Mean Squared Error, RRMSE = 8-25). The simplest model (with one pool for ST and one for PS) strongly overestimated SMN immobilisation from day 3 to day 21, both in the treatments with AS15 and PS15 (RRMSE = 27-30%). The other two models represented rather well the dynamics of SMN in the soil (RRMSE = 21-25%), simulating a fast increase of nitrate concentration in the first days, and slower rates of nitrification thereafter. Worse performances were obtained with all models for the simulation of SM-15N in the treatment with ST15 (RRMSE = 64-104%): experimental data showed positive mineralization of stalk-derived N from the beginning of the incubation, while models strongly underestimated

  1. Thermodynamic modeling of CO2 mixtures

    DEFF Research Database (Denmark)

    Bjørner, Martin Gamel

    Knowledge of the thermodynamic properties and phase equilibria of mixtures containing carbon dioxide (CO2) is important in several industrial processes such as enhanced oil recovery, carbon capture and storage, and supercritical extractions, where CO2 is used as a solvent. Despite this importance......, accurate predictions of the thermodynamic properties and phase equilibria of mixtures containing CO2 are challenging with classical models such as the Soave-Redlich-Kwong (SRK) equation of state (EoS). This is believed to be due to the fact, that CO2 has a large quadrupole moment which the classical models...... and with or without introducing an additional pure compound parameter. In the absence of quadrupolar compounds qCPA reduces to CPA, which itself reduces toSRK in the absence of association. As the number of adjustable parameters in thermodynamic models increase, the parameter estimation problem becomes increasingly...

  2. Spatial Variability in Column CO2 Inferred from High Resolution GEOS-5 Global Model Simulations: Implications for Remote Sensing and Inversions

    Science.gov (United States)

    Ott, L.; Putman, B.; Collatz, J.; Gregg, W.

    2012-01-01

    Column CO2 observations from current and future remote sensing missions represent a major advancement in our understanding of the carbon cycle and are expected to help constrain source and sink distributions. However, data assimilation and inversion methods are challenged by the difference in scale of models and observations. OCO-2 footprints represent an area of several square kilometers while NASA s future ASCENDS lidar mission is likely to have an even smaller footprint. In contrast, the resolution of models used in global inversions are typically hundreds of kilometers wide and often cover areas that include combinations of land, ocean and coastal areas and areas of significant topographic, land cover, and population density variations. To improve understanding of scales of atmospheric CO2 variability and representativeness of satellite observations, we will present results from a global, 10-km simulation of meteorology and atmospheric CO2 distributions performed using NASA s GEOS-5 general circulation model. This resolution, typical of mesoscale atmospheric models, represents an order of magnitude increase in resolution over typical global simulations of atmospheric composition allowing new insight into small scale CO2 variations across a wide range of surface flux and meteorological conditions. The simulation includes high resolution flux datasets provided by NASA s Carbon Monitoring System Flux Pilot Project at half degree resolution that have been down-scaled to 10-km using remote sensing datasets. Probability distribution functions are calculated over larger areas more typical of global models (100-400 km) to characterize subgrid-scale variability in these models. Particular emphasis is placed on coastal regions and regions containing megacities and fires to evaluate the ability of coarse resolution models to represent these small scale features. Additionally, model output are sampled using averaging kernels characteristic of OCO-2 and ASCENDS measurement

  3. TransCom model simulations of hourly atmospheric CO2: Analysis of synoptic-scale variations for the period 2002-2003

    NARCIS (Netherlands)

    Patra, P. K.; Law, R. M.; Peters, W.; RöDenbeck, C.; Takigawa, M.; Aulagnier, C.; Baker, I.; Bergmann, D. J.; Bousquet, P.; Brandt, J.; Bruhwiler, L.; Cameron-Smith, P. J.; Christensen, J. H.; Delage, F.; Denning, A. S.; Fan, S.; Geels, C.; Houweling, S.; Imasu, R.; Karstens, U.; Kawa, S. R.; Kleist, J.; Krol, M. C.; Lin, S.-J.; Lokupitiya, R.; Maki, T.; Maksyutov, S.; Niwa, Y.; Onishi, R.; Parazoo, N.; Pieterse, G.; Rivier, L.; Satoh, M.; Serrar, S.; Taguchi, S.; Vautard, R.; Vermeulen, A. T.; Zhu, Z.

    2008-01-01

    The ability to reliably estimate CO2 fluxes from current in situ atmospheric CO2 measurements and future satellite CO2 measurements is dependent on transport model performance at synoptic and shorter timescales. The TransCom continuous experiment was designed to evaluate the performance of forward

  4. Forecasting carbon budget under climate change and CO2 fertilization for subtropical region in China using integrated biosphere simulator (IBIS) model

    Science.gov (United States)

    Zhu, Q.; Jiang, H.; Liu, J.; Peng, C.; Fang, X.; Yu, S.; Zhou, G.; Wei, X.; Ju, W.

    2011-01-01

    The regional carbon budget of the climatic transition zone may be very sensitive to climate change and increasing atmospheric CO2 concentrations. This study simulated the carbon cycles under these changes using process-based ecosystem models. The Integrated Biosphere Simulator (IBIS), a Dynamic Global Vegetation Model (DGVM), was used to evaluate the impacts of climate change and CO2 fertilization on net primary production (NPP), net ecosystem production (NEP), and the vegetation structure of terrestrial ecosystems in Zhejiang province (area 101,800 km2, mainly covered by subtropical evergreen forest and warm-temperate evergreen broadleaf forest) which is located in the subtropical climate area of China. Two general circulation models (HADCM3 and CGCM3) representing four IPCC climate change scenarios (HC3AA, HC3GG, CGCM-sresa2, and CGCM-sresb1) were used as climate inputs for IBIS. Results show that simulated historical biomass and NPP are consistent with field and other modelled data, which makes the analysis of future carbon budget reliable. The results indicate that NPP over the entire Zhejiang province was about 55 Mt C yr-1 during the last half of the 21st century. An NPP increase of about 24 Mt C by the end of the 21st century was estimated with the combined effects of increasing CO2 and climate change. A slight NPP increase of about 5 Mt C was estimated under the climate change alone scenario. Forests in Zhejiang are currently acting as a carbon sink with an average NEP of about 2.5 Mt C yr-1. NEP will increase to about 5 Mt C yr-1 by the end of the 21st century with the increasing atmospheric CO2 concentration and climate change. However, climate change alone will reduce the forest carbon sequestration of Zhejiang's forests. Future climate warming will substantially change the vegetation cover types; warm-temperate evergreen broadleaf forest will be gradually substituted by subtropical evergreen forest. An increasing CO2 concentration will have little

  5. TOUGH+CO 2: A multiphase fluid-flow simulator for CO 2 geologic sequestration in saline aquifers

    Science.gov (United States)

    Zhang, Keni; Moridis, George; Pruess, Karsten

    2011-06-01

    TOUGH+CO 2 is a new simulator for modeling of CO 2 geologic sequestration in saline aquifers. It is a member of TOUGH+, the successor to the TOUGH2 family of codes for multicomponent, multiphase fluid and heat flow simulation. The code accounts for heat and up to 3 mass components, which are partitioned into three possible phases. In the code, the thermodynamics and thermophysical properties of H 2O-NaCl-CO 2 mixtures are determined based on system status and subdivided into six different phase combinations. By solving coupled mass and heat balance equations, TOUGH+CO 2 can model non-isothermal or isothermal CO 2 injection, phase behavior and flow of fluids and heat under typical conditions of temperature, pressure and salinity in CO 2 geologic storage projects. The code takes into account effects of salt precipitation on porosity and permeability changes, and the wettability phenomena. The new simulator inherits all capabilities of TOUGH2 in handling fractured media and using unstructured meshes for complex simulation domains. The code adds additional relative permeability and capillary pressure functions. The FORTRAN 95 OOP architecture and other new language features have been extensively used to enhance memory use and computing efficiency. In addition, a domain decomposition approach has been implemented for parallel simulation. All these features lead to increased computational efficiency, and allow applicability of the code to multi-core/processor parallel computing platforms with excellent scalability.

  6. Simulation Studies of Satellite Laser CO2 Mission Concepts

    Science.gov (United States)

    Kawa, S. R.; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun, X.; Weaver, C. J.; Browell, E. V.

    2011-12-01

    Results of mission simulation studies are presented for a laser-based atmospheric CO2 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to ASCENDS as recommended by the US National Academy of Sciences Decadal Survey. Compared to passive sensors, active (lidar) sensing of CO2 from space has several potentially significant advantages that hold promise to advance CO2 measurement capability in the next decade. Although the precision and accuracy requirements remain at unprecedented levels of stringency, analysis of possible instrument technology indicates that such sensors are more than feasible. As a prerequisite for quantitative sensor evaluation we have assembled a relatively complete description of the atmospheric and surface state that is needed to estimate the random error component of prospective CO2 measurements. The state is obtained from meteorological data assimilation and satellite measurements from MODIS and CALIPSO. The resulting error distributions will be used in inverse studies to estimate the fidelity of surface flux estimation from the laser observations. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudo-data" CO2 with error bounds. The results indicate that within reasonable technological assumptions for the system performance, high measurement precision can be obtained that will fulfill the nominal ASCENDS objectives. Several mission and instrument configuration options are examined, and the sensitivity to key design variables is shown. Examples are also shown of how the resulting pseudo-measurements might be used to address key carbon cycle science questions.

  7. Application of a terrestrial ecosystem model (ORCHIDEE-STICS) in simulating energy and CO2 fluxes in Asian rice croplands

    Science.gov (United States)

    Wang, X.; Piao, S.; Ciais, P.; Vuichard, N.

    2012-12-01

    Process-based terrestrial ecosystem models have shown great potentials in predicting the response of managed ecosystems to environmental changes. However, the simulated water and carbon fluxes over rice ecosystems in tropical Asia are still subject to large uncertainties, partly due to poorly constrained parameters in the models. Here, a terrestrial ecosystem model incorporating a more realistic crop module (ORCHIDEE-STICS) was calibrated against in-situ flux data and observed and remotely sensed leaf area indexes over rice ecosystems in Asia. The key parameters adjusted include maximum photosynthetic carboxylation rate (Vcmax) and electron transport rate (Vjmax), temperature sensitivity of heterotrophic respiration (Q10) and a series of critical thresholds for different crop development stages. Compared with the observations, the calibrated model more realistically simulated the seasonal and year-to-year variation of the observed water and carbon fluxes with reductions in the root mean square difference and better timing in the crop development stages. Sensitivity tests further reveal that management practices like the timing of transplanting and draining could affect the seasonal and inter-annual variation of the net carbon exchange, suggesting that the absence of explicit accounting the change of management practices in the terrestrial ecosystem models may induce large uncertainties in predicting cropland ecosystem response to future climate change.

  8. Constraining a complex biogeochemical model for CO2 and N2O emission simulations from various land uses by model–data fusion

    Directory of Open Access Journals (Sweden)

    T. Houska

    2017-07-01

    Full Text Available This study presents the results of a combined measurement and modelling strategy to analyse N2O and CO2 emissions from adjacent arable land, forest and grassland sites in Hesse, Germany. The measured emissions reveal seasonal patterns and management effects, including fertilizer application, tillage, harvest and grazing. The measured annual N2O fluxes are 4.5, 0.4 and 0.1 kg N ha−1 a−1, and the CO2 fluxes are 20.0, 12.2 and 3.0 t C ha−1 a−1 for the arable land, grassland and forest sites, respectively. An innovative model–data fusion concept based on a multicriteria evaluation (soil moisture at different depths, yield, CO2 and N2O emissions is used to rigorously test the LandscapeDNDC biogeochemical model. The model is run in a Latin-hypercube-based uncertainty analysis framework to constrain model parameter uncertainty and derive behavioural model runs. The results indicate that the model is generally capable of predicting trace gas emissions, as evaluated with RMSE as the objective function. The model shows a reasonable performance in simulating the ecosystem C and N balances. The model–data fusion concept helps to detect remaining model errors, such as missing (e.g. freeze–thaw cycling or incomplete model processes (e.g. respiration rates after harvest. This concept further elucidates the identification of missing model input sources (e.g. the uptake of N through shallow groundwater on grassland during the vegetation period and uncertainty in the measured validation data (e.g. forest N2O emissions in winter months. Guidance is provided to improve the model structure and field measurements to further advance landscape-scale model predictions.

  9. Simulation of Stomatal Conductance and Water Use Efficiency of Tomato Leaves Exposed to Different Irrigation Regimes and Air CO2 Concentrations by a Modified “Ball-Berry” Model

    Directory of Open Access Journals (Sweden)

    Zhenhua Wei

    2018-04-01

    Full Text Available Stomatal conductance (gs and water use efficiency (WUE of tomato leaves exposed to different irrigation regimes and at ambient CO2 (a[CO2], 400 ppm and elevated CO2 (e[CO2], 800 ppm environments were simulated using the “Ball-Berry” model (BB-model. Data obtained from a preliminary experiment (Exp. I was used for model parameterization, where measurements of leaf gas exchange of potted tomatoes were done during progressive soil drying for 5 days. The measured photosynthetic rate (Pn was used as an input for the model. Considering the effect of soil water deficits on gs, an equation modifying the slope (m based on the mean soil water potential (Ψs in the whole root zone was introduced. Compared to the original BB-model, the modified model showed greater predictability for both gs and WUE of tomato leaves at each [CO2] growth environment. The models were further validated with data obtained from an independent experiment (Exp. II where plants were subjected to three irrigation regimes: full irrigation (FI, deficit irrigation (DI, and alternative partial root-zone irrigation (PRI for 40 days at both a[CO2] and e[CO2] environment. The simulation results indicated that gs was independently acclimated to e[CO2] from Pn. The modified BB-model performed better in estimating gs and WUE, especially for PRI strategy at both [CO2] environments. A greater WUE could be seen in plants grown under e[CO2] associated with PRI regime. Conclusively, the modified BB-model was capable of predicting gs and WUE of tomato leaves in various irrigation regimes at both a[CO2] and e[CO2] environments. This study could provide valuable information for better predicting plant WUE adapted to the future water-limited and CO2 enriched environment.

  10. Ecosystem service impacts of future changes in CO2, climate, and land use as simulated by a coupled vegetation/land-use model system

    Science.gov (United States)

    Rabin, S. S.; Alexander, P.; Henry, R.; Anthoni, P.; Pugh, T.; Rounsevell, M.; Arneth, A.

    2017-12-01

    In a future of increasing atmospheric carbon dioxide (CO2) concentrations, changing climate, increasing human populations, and changing socioeconomic dynamics, the global agricultural system will need to adapt in order to feed the world. Global modeling can help to explore what these adaptations will look like, and their potential impacts on ecosystem services. To do so, however, the complex interconnections among the atmosphere, terrestrial ecosystems, and society mean that these various parts of the Earth system must be examined as an interconnected whole. With the goal of answering these questions, a model system has been developed that couples a biologically-representative global vegetation model, LPJ-GUESS, with the PLUMv2 land use model. LPJ-GUESS first simulates—at 0.5º resolution across the world—the potential yield of various crops and pasture under a range of management intensities for a time step given its atmospheric CO2 level and climatic forcings. These potential yield simulations are fed into PLUMv2, which uses them in conjunction with endogenous agricultural commodity demand and prices to produce land use and management inputs (fertilizer and irrigation water) at a sub-national level for the next time step. This process is performed through 2100 for a range of future climate and societal scenarios—the Representative Concentration Pathways (RCPs) and the Shared Socioeconomic Pathways (SSPs), respectively—providing a thorough exploration of possible trajectories of land use and land cover change. The land use projections produced by PLUMv2 are fed back into LPJ-GUESS to simulate the future impacts of land use change, along with increasing CO2 and climate change, on terrestrial ecosystems. This integrated analysis examines the resulting impacts on regulating and provisioning ecosystem services affecting biophysics (albedo); carbon, nitrogen, and water cycling; and the emission of biogenic volatile organic compounds (BVOCs).

  11. Simulation and thermodynamic modeling of the extraction of tocopherol from a synthetic mixture of tocopherol, squalene and CO2

    Directory of Open Access Journals (Sweden)

    M.F. Mendes

    2000-12-01

    Full Text Available Soybean oil is the most consumed vegetable oil in the world, representing 54% of the total world production. Brazil is the second country in the world that produces and export soybean seeds, almost 20%. One of the most important by-product of the soybean oil is the deodorizer distillate, commonly known as soybean sludge. This residue is rich in many high value compounds as tocopherols, squalene and sterols. Tocopherols are the major components in the deodorized distillated due to their characteristics as an antioxidant agent. So, the objective of this work is to study the concentration of tocopherols presented in this raw material, using the operational conditions obtained from the equilibrium data and using supercritical carbon dioxide as a solvent. The deodorizer distillate is a complex mixture of more than 200 components, so a synthetic mixture was chosen to represent the deodorizer distillate. The synthetic mixture used in this work is composed by tocopherols, fatty acids and squalene. The simulation was carried out using ASPEN+ simulator and the LCVM thermodynamic model was used to correlate the available equilibrium data.

  12. Modelling the Martian CO2 Ice Clouds

    Science.gov (United States)

    Listowski, Constantino; Määttänen, A.; Montmessin, F.; Lefèvre, F.

    2012-10-01

    Martian CO2 ice cloud formation represents a rare phenomenon in the Solar System: the condensation of the main component of the atmosphere. Moreover, on Mars, condensation occurs in a rarefied atmosphere (large Knudsen numbers, Kn) that limits the growth efficiency. These clouds form in the polar winter troposphere and in the mesosphere near the equator. CO2 ice cloud modeling has turned out to be challenging: recent efforts (e.g. [1]) fail in explaining typical small sizes (80 nm-130 nm) observed for mesospheric clouds [2]. Supercold pockets (TWood, S. E., (1999), Ph.D. thesis, UCLA [6] Young, J. B., J. Geophys. Res., 36, 294-2956, 1993

  13. MODEL SIMULASI EMISI DAN PENYERAPAN CO2 DI KOTA BOGOR

    Directory of Open Access Journals (Sweden)

    Rizka Permatayakti Rasyidta Nur

    2015-04-01

    Full Text Available Most of the urban pollution is the result of carbon dioxide (CO2 emission from human activities. This research identified CO2 emission and absorption in Bogor, and also the alternatives to solve the emission problem by system model and simulation. CO2 emission and absorption system model was created using software Stella 9.0.2 based on loss-gain emission concept for 30 years prediction. Human activities that contribute to CO2 emission are transportation, industries, energy consumption such as fuel or electricity, house hold waste, and farms, while the decrease factor is green open spaces as CO2 sequester. The alternatives to solve emission problem in Bogor is created based on green city concept by including the environmental aspects in every urban activity. The result of this research, the CO2 emission of Bogor reached 20.027.878 tons and the absorption reached 93.843 tons in 2042. Combined mitigation alternatives in several sectors could reduce CO2 emission by 2.797.667 tons in 2042 and CO2 emission could be neutralized by reforestation in 2036.

  14. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-01-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations. PMID:26838480

  15. Modeling of CO2 migration injected in Weyburn oil reservoir

    International Nuclear Information System (INIS)

    Zhou Wei; Stenhouse, M.J.; Arthur, R.

    2008-01-01

    Injecting CO 2 into oil and gas field is a way to enhance oil recovery (EOR) as well as mitigate global warming effect by permanently storing the greenhouse gas into underground. This paper details the models and results of simulating the long-term migration of CO 2 injected into the Weyburn field for both Enhanced Oil Recovery operations and CO 2 sequestration. A System Model was established to define the spatial and temporal extents of the analysis. The Base Scenario was developed to identify key processes, features, and events (FEPs) for the expected evolution of the storage system. A compositional reservoir simulator with equations-of-states (EOS) was used as the modeling tool in order to simulate multiphase, multi-component flow and transport coupled with CO 2 mass partitioning into oil, gas, and water phases. We apply a deterministic treatment to CO 2 migration in the geosphere (natural pathways), whereas the variability of abandoned wells (man-made pathways) necessitates a stochastic treatment. The simulation result was then used to carry out consequence analysis to the local environment. (authors)

  16. Gaussian-Charge Polarizable and Nonpolarizable Models for CO2.

    Science.gov (United States)

    Jiang, Hao; Moultos, Othonas A; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2016-02-11

    A polarizable intermolecular potential model using three classical Drude oscillators on the atomic sites has been developed for CO2. The model is rigid with bond lengths and molecular geometries set to their experimental values. Electrostatic interactions are represented by three Gaussian charges connected to the molecular frame by harmonic springs. Nonelectrostatic interactions are represented by the Buckingham exponential-6 potential, with potential parameters optimized to vapor-liquid equilibria (VLE) data. A nonpolarizable CO2 model that shares the other ingredients of the polarizable model was also developed and optimized to VLE data. Gibbs ensemble Monte Carlo and molecular dynamics simulations were used to evaluate the two models with respect to a variety of thermodynamic and transport properties, including the enthalpy of vaporization, second virial coefficient, density in the one-phase fluid region, isobaric and isochoric heat capacities, radial distribution functions, self-diffusion coefficient, and shear viscosity. Excellent agreement between model predictions and experimental data was found for all properties studied. The polarizable and nonpolarizable models provide a similar representation of CO2 properties, which indicates that the properties of pure CO2 fluid are not strongly affected by polarization. The polarizable model, which has an order of magnitude higher computational cost than the nonpolarizable model, will likely be useful for the study of a mixture of CO2 and polar components for which polarization is important.

  17. Effect of heterogeneousatmospheric CO2 on simulated global carbon budget

    Science.gov (United States)

    Zhang, Zhen; Jiang, Hong; Liu, Jinxun; Ju, Weimin; Zhang, Xiuying

    2013-01-01

    The effects of rising atmospheric carbon dioxide (CO2) on terrestrial carbon (C) sequestration have been a key focus in global change studies. As anthropological CO2 emissions substantially increase, the spatial variability of atmospheric CO2 should be considered to reduce the potential bias on C source and sink estimations. In this study, the global spatial–temporal patterns of near surface CO2 concentrations for the period 2003-2009 were established using the SCIAMACHY satellite observations and the GLOBALVIEW-CO2 field observations. With this CO2 data and the Integrated Biosphere Simulator (IBIS), our estimation of the global mean annual NPP and NEP was 0.5% and 7% respectively which differs from the traditional C sequestration assessments. The Amazon, Southeast Asia, and Tropical Africa showed higher C sequestration than the traditional assessment, and the rest of the areas around the world showed slightly lower C sequestration than the traditional assessment. We find that the variability of NEP is less intense under heterogeneous CO2 pattern on a global scale. Further studies of the cause of CO2 variation and the interactions between natural and anthropogenic processes of C sequestration are needed.

  18. The Influence of CO2 Solubility in Brine on Simulation of CO2 Injection into Water Flooded Reservoir and CO2 WAG

    DEFF Research Database (Denmark)

    Yan, Wei; Stenby, Erling Halfdan

    2010-01-01

    Injection of CO2 into depleted oil reservoirs is not only a traditional way to enhance oil recovery but also a relatively cheaper way to sequester CO2 underground since the increased oil production can offset some sequestration cost. CO2 injection process is often applied to water flooded...... reservoirs and in many situations alternating injection of water and CO2 is required to stabilize the injection front. Both scenarios involve a large amount of water, making CO2 solubility in brine, which is around ten times higher than methane solubility, a non-negligible factor in the relevant reservoir...... simulations. In our previous study, a 1-D slimtube simulator, which rigorously accounts for both CO2 solubility in brine and water content in hydrocarbon phases using the Peng-Robinson EoS modified by Soreide and Whitson, has been used to investigate the influence of CO2 solubility on the simulation...

  19. Model analyses for sustainable energy supply under CO2 restrictions

    International Nuclear Information System (INIS)

    Matsuhashi, Ryuji; Ishitani, Hisashi.

    1995-01-01

    This paper aims at clarifying key points for realizing sustainable energy supply under restrictions on CO 2 emissions. For this purpose, possibility of solar breeding system is investigated as a key technology for the sustainable energy supply. The authors describe their mathematical model simulating global energy supply and demand in ultra-long term. Depletion of non-renewable resources and constraints on CO 2 emissions are taken into consideration in the model. Computed results have shown that present energy system based on non-renewable resources shifts to a system based on renewable resources in the ultra-long term with appropriate incentives

  20. Simulation of anthropogenic CO2 uptake in the CCSM3.1 ocean circulation-biogeochemical model: comparison with data-based estimates

    Science.gov (United States)

    Wang, S.; Moore, J. K.; Primeau, F. W.; Khatiwala, S.

    2012-04-01

    The global ocean has taken up a large fraction of the CO2 released by human activities since the industrial revolution. Quantifying the oceanic anthropogenic carbon (Cant) inventory and its variability is important for predicting the future global carbon cycle. The detailed comparison of data-based and model-based estimates is essential for the validation and continued improvement of our prediction capabilities. So far, three global estimates of oceanic Cant inventory that are "data-based" and independent of global ocean circulation models have been produced: one based on the Δ C* method, and two that are based on constraining surface-to-interior transport of tracers, the TTD method and a maximum entropy inversion method (GF). The GF method, in particular, is capable of reconstructing the history of Cant inventory through the industrial era. In the present study we use forward model simulations of the Community Climate System Model (CCSM3.1) to estimate the Cant inventory and compare the results with the data-based estimates. We also use the simulations to test several assumptions of the GF method, including the assumption of constant climate and circulation, which is common to all the data-based estimates. Though the integrated estimates of global Cant inventories are consistent with each other, the regional estimates show discrepancies up to 50 %. The CCSM3 model underestimates the total Cant inventory, in part due to weak mixing and ventilation in the North Atlantic and Southern Ocean. Analyses of different simulation results suggest that key assumptions about ocean circulation and air-sea disequilibrium in the GF method are generally valid on the global scale, but may introduce errors in Cant estimates on regional scales. The GF method should also be used with caution when predicting future oceanic anthropogenic carbon uptake.

  1. Simulation of anthropogenic CO2 uptake in the CCSM3.1 ocean circulation-biogeochemical model: comparison with data-based estimates

    Directory of Open Access Journals (Sweden)

    S. Khatiwala

    2012-04-01

    Full Text Available The global ocean has taken up a large fraction of the CO2 released by human activities since the industrial revolution. Quantifying the oceanic anthropogenic carbon (Cant inventory and its variability is important for predicting the future global carbon cycle. The detailed comparison of data-based and model-based estimates is essential for the validation and continued improvement of our prediction capabilities. So far, three global estimates of oceanic Cant inventory that are "data-based" and independent of global ocean circulation models have been produced: one based on the Δ C* method, and two that are based on constraining surface-to-interior transport of tracers, the TTD method and a maximum entropy inversion method (GF. The GF method, in particular, is capable of reconstructing the history of Cant inventory through the industrial era. In the present study we use forward model simulations of the Community Climate System Model (CCSM3.1 to estimate the Cant inventory and compare the results with the data-based estimates. We also use the simulations to test several assumptions of the GF method, including the assumption of constant climate and circulation, which is common to all the data-based estimates. Though the integrated estimates of global Cant inventories are consistent with each other, the regional estimates show discrepancies up to 50 %. The CCSM3 model underestimates the total Cant inventory, in part due to weak mixing and ventilation in the North Atlantic and Southern Ocean. Analyses of different simulation results suggest that key assumptions about ocean circulation and air-sea disequilibrium in the GF method are generally valid on the global scale, but may introduce errors in Cant estimates on regional scales. The GF method should also be used with caution when predicting future oceanic anthropogenic carbon uptake.

  2. Modelling CO2-Brine Interfacial Tension using Density Gradient Theory

    KAUST Repository

    Ruslan, Mohd Fuad Anwari Che

    2018-03-01

    Knowledge regarding carbon dioxide (CO2)-brine interfacial tension (IFT) is important for petroleum industry and Carbon Capture and Storage (CCS) strategies. In petroleum industry, CO2-brine IFT is especially importance for CO2 – based enhanced oil recovery strategy as it affects phase behavior and fluid transport in porous media. CCS which involves storing CO2 in geological storage sites also requires understanding regarding CO2-brine IFT as this parameter affects CO2 quantity that could be securely stored in the storage site. Several methods have been used to compute CO2-brine interfacial tension. One of the methods employed is by using Density Gradient Theory (DGT) approach. In DGT model, IFT is computed based on the component density distribution across the interface. However, current model is only applicable for modelling low to medium ionic strength solution. This limitation is due to the model only considers the increase of IFT due to the changes of bulk phases properties and does not account for ion distribution at interface. In this study, a new modelling strategy to compute CO2-brine IFT based on DGT was proposed. In the proposed model, ion distribution across interface was accounted for by separating the interface to two sections. The saddle point of tangent plane distance where ( ) was defined as the boundary separating the two sections of the interface. Electrolyte is assumed to be present only in the second section which is connected to the bulk liquid phase side. Numerical simulations were performed using the proposed approach for single and mixed salt solutions for three salts (NaCl, KCl, and CaCl2), for temperature (298 K to 443 K), pressure (2 MPa to 70 MPa), and ionic strength (0.085 mol·kg-1 to 15 mol·kg-1). The simulation result shows that the tuned model was able to predict with good accuracy CO2-brine IFT for all studied cases. Comparison with current DGT model showed that the proposed approach yields better match with the experiment data

  3. Spatial and temporal variability of column-integrated CO2: identifying drivers and variations from high-resolution model simulations and OCO-2 observations

    Science.gov (United States)

    Chatterjee, A.; Ott, L.; Wennberg, P. O.; Kawa, S. R.; O'Dell, C.; Osterman, G. B.; Wunch, D.

    2015-12-01

    Isolating the drivers and variations in column-averaged dry air mole fraction of carbon dioxide (XCO2) is essential for mining information from space-based remote-sensing observations, such as those available from the Orbiting Carbon Observatory-2 (OCO-2). Contrary to the large number of studies analyzing the variability of surface CO2 concentrations, studies analyzing the spatiotemporal variability of XCO2 are relatively limited. More importantly, these results are either based on a sparse network of ground-based total column observations (i.e., from the Total Column Carbon Observing Network - TCCON) or derived from low-resolution model simulations. In this study, using the high-resolution (~7 km) GEOS-5 model simulated fields and the high-density observations from OCO-2, we investigate how variability in surface fluxes and/or meteorological drivers impact the observed XCO2 variability across a range of scales. The study focuses on ~13:30 LT and is designed to highlight the significant contributors to local and regional scale XCO2 variability from daily to seasonal timescales. In collaboration with the OCO-2 Validation team, the variability information is also being used to identify small geographical areas (<1° or ~100km) where the XCO2 is expected to be relatively constant. These small areas then serve as target regions for examining the potential of external variables (for e.g., surface reflectance, aerosol) to generate biases (variability) in the XCO2 retrievals in those regions. We will also show comparison results of the model-based variability analyses with the variability statistics derived from actual OCO-2 retrievals. This comparison serves as an important consistency check for the simulated fields from the GEOS-5 model. Finally, we will review these results in terms of assessing and quantifying representation errors as well as developing and implementing data thinning/'superobbing' algorithms for OCO-2 retrievals.

  4. Simulated response of conterminous United States ecosystems to climate change at different levels of fire suppression, CO2 emission rate, and growth response to CO2

    Science.gov (United States)

    James M. Lenihan; Dominique Bachelet; Ronald P. Neilson; Raymond Drapek

    2008-01-01

    A modeling experiment was designed to investigate the impact of fire management, CO2 emission rate, and the growth response to CO2 on the response of ecosystems in the conterminous United States to climate scenarios produced by three different general circulation models (GCMs) as simulated by the MCl Dynamic General...

  5. Simulation of CO2 Injection in Porous Media with Structural Deformation Effect

    KAUST Repository

    Negara, Ardiansyah

    2011-06-18

    Carbon dioxide (CO2) sequestration is one of the most attractive methods to reduce the amount of CO2 in the atmosphere by injecting it into the geological formations. Furthermore, it is also an effective mechanism for enhanced oil recovery. Simulation of CO2 injection based on a suitable modeling is very important for explaining the fluid flow behavior of CO2 in a reservoir. Increasing of CO2 injection may cause a structural deformation of the medium. The structural deformation modeling in carbon sequestration is useful to evaluate the medium stability to avoid CO2 leakage to the atmosphere. Therefore, it is important to include such effect into the model. The purpose of this study is to simulate the CO2 injection in a reservoir. The numerical simulations of two-phase flow in homogeneous and heterogeneous porous media are presented. Also, the effects of gravity and capillary pressure are considered. IMplicit Pressure Explicit Saturation (IMPES) and IMplicit Pressure-Displacements and an Explicit Saturation (IMPDES) schemes are used to solve the problems under consideration. Various numerical examples were simulated and divided into two parts of the study. The numerical results demonstrate the effects of buoyancy and capillary pressure as well as the permeability value and its distribution in the domain. Some conclusions that could be derived from the numerical results are the buoyancy of CO2 is driven by the density difference, the CO2 saturation profile (rate and distribution) are affected by the permeability distribution and its value, and the displacements of the porous medium go to constant values at least six to eight months (on average) after injection. Furthermore, the simulation of CO2 injection provides intuitive knowledge and a better understanding of the fluid flow behavior of CO2 in the subsurface with the deformation effect of the porous medium.

  6. A Test of Sensitivity to Convective Transport in a Global Atmospheric CO2 Simulation

    Science.gov (United States)

    Bian, H.; Kawa, S. R.; Chin, M.; Pawson, S.; Zhu, Z.; Rasch, P.; Wu, S.

    2006-01-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. GlobalCO2 in the year 2000 is simulated using theCTM driven by assimilated meteorological fields from the NASA s Goddard Earth Observation System Data Assimilation System, Version 4 (GEOS-4). The model simulates atmospheric CO2 by adopting the same CO2 emission inventory and dynamical modules as described in Kawa et al. (convective transport scheme denoted as Conv1). Conv1 approximates the convective transport by using the bulk convective mass fluxes to redistribute trace gases. The alternate approximation, Conv2, partitions fluxes into updraft and downdraft, as well as into entrainment and detrainment, and has potential to yield a more realistic simulation of vertical redistribution through deep convection. Replacing Conv1 by Conv2 results in an overestimate of CO2 over biospheric sink regions. The largest discrepancies result in a CO2 difference of about 7.8 ppm in the July NH boreal forest, which is about 30% of the CO2 seasonality for that area. These differences are compared to those produced by emission scenario variations constrained by the framework of Intergovernmental Panel on Climate Change (IPCC) to account for possible land use change and residual terrestrial CO2 sink. It is shown that the overestimated CO2 driven by Conv2 can be offset by introducing these supplemental emissions.

  7. A Polarizable and Transferable PHAST CO 2 Potential for Materials Simulation

    KAUST Repository

    Mullen, Ashley L.

    2013-12-10

    Reliable PHAST (Potentials with High Accuracy Speed and Transferability) intermolecular potential energy functions for CO2 have been developed from first principles for use in heterogeneous systems, including one with explicit polarization. The intermolecular potentials have been expressed in a transferable form and parametrized from nearly exact electronic structure calculations. Models with and without explicit many-body polarization effects, known to be important in simulation of interfacial processes, are constructed. The models have been validated on pressure-density isotherms of bulk CO 2 and adsorption in three metal-organic framework (MOF) materials. The present models appear to offer advantages over high quality fluid/liquid state potentials in describing CO2 interactions in interfacial environments where sorbates adopt orientations not commonly explored in bulk fluids. Thus, the nonpolar CO2-PHAST and polarizable CO 2-PHAST* potentials are recommended for materials/interfacial simulations. © 2013 American Chemical Society.

  8. Modeling of CO2 absorber using an AMP solution

    DEFF Research Database (Denmark)

    Gabrielsen, Jostein; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2006-01-01

    Abstract: An explicit model for carbon dioxide (CO2) solubility in an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) has been proposed and an expression for the heat of absorption of CO2 has been developed as a function of loading and temperature. A rate-based steady-state model for CO2...

  9. Simplified Predictive Models for CO2 Sequestration Performance Assessment

    Science.gov (United States)

    Mishra, Srikanta; RaviGanesh, Priya; Schuetter, Jared; Mooney, Douglas; He, Jincong; Durlofsky, Louis

    2014-05-01

    We present results from an ongoing research project that seeks to develop and validate a portfolio of simplified modeling approaches that will enable rapid feasibility and risk assessment for CO2 sequestration in deep saline formation. The overall research goal is to provide tools for predicting: (a) injection well and formation pressure buildup, and (b) lateral and vertical CO2 plume migration. Simplified modeling approaches that are being developed in this research fall under three categories: (1) Simplified physics-based modeling (SPM), where only the most relevant physical processes are modeled, (2) Statistical-learning based modeling (SLM), where the simulator is replaced with a "response surface", and (3) Reduced-order method based modeling (RMM), where mathematical approximations reduce the computational burden. The system of interest is a single vertical well injecting supercritical CO2 into a 2-D layered reservoir-caprock system with variable layer permeabilities. In the first category (SPM), we use a set of well-designed full-physics compositional simulations to understand key processes and parameters affecting pressure propagation and buoyant plume migration. Based on these simulations, we have developed correlations for dimensionless injectivity as a function of the slope of fractional-flow curve, variance of layer permeability values, and the nature of vertical permeability arrangement. The same variables, along with a modified gravity number, can be used to develop a correlation for the total storage efficiency within the CO2 plume footprint. In the second category (SLM), we develop statistical "proxy models" using the simulation domain described previously with two different approaches: (a) classical Box-Behnken experimental design with a quadratic response surface fit, and (b) maximin Latin Hypercube sampling (LHS) based design with a Kriging metamodel fit using a quadratic trend and Gaussian correlation structure. For roughly the same number of

  10. Mesoscale covariance of transport and CO2 fluxes: Evidence from observations and simulations using the WRF-VPRM coupled atmosphere-biosphere model

    NARCIS (Netherlands)

    Ahmadov, R.; Gerbig, C.; Kretschmer, R.; Koerner, S.; Neininger, B.; Dolman, A.J.; Sarrat, C.

    2007-01-01

    We developed a modeling system which combines a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, with a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration (VPRM). The WRF-VPRM modeling system was designed to realistically simulate

  11. Simulating the effect of elevated CO2 on crops : approaches and application for climate change

    NARCIS (Netherlands)

    Tubiello, F.N.; Ewert, F.

    2002-01-01

    Several crop models may be used to simulate the effects of elevated CO2 on crop productivity. Yet no summary exists in the literature attempting to describe differences among models and how simulations might differ under climate change conditions. We provide an introductory review focusing on

  12. Modeling CO2-facilitated transport across a diethanolamine liquid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Lihong Bao; Michael C. Trachtenberg [Carbozyme Inc., Monmouth Junction, NJ (United States)

    2005-12-15

    We compared experimental and model data for the facilitated transport of CO2 from a CO2-air mixture across an aqueous solution of diethanolamine (DEA) via a hollow fiber, contained liquid membrane (HFCLM) permeator. A two-step carbamate formation model was devised to analyze the data instead of the one-step mechanism used by previous investigators. The effects of DEA concentration, liquid membrane thickness and feed CO2 concentration were also studied. With a 20% (wt) DEA liquid membrane and feed of 15% CO2 in CO2-air mixture at atmosphere pressure, the permeance reached 1.51E-8 mol/m{sup 2} s Pa with a CO2/N2 selectivity of 115. Model predictions compared well with the experimental results at CO2 concentrations of industrial importance. Short-term stability of the HFCLM permeator performance was examined. The system was stable during 5-days of testing.

  13. Modeling canopy CO2 exchange in the European Russian Arctic

    DEFF Research Database (Denmark)

    Kiepe, Isabell; Friborg, Thomas; Herbst, Mathias

    2013-01-01

    In this study, we use the coupled photosynthesis-stomatal conductance model of Collatz et al. (1991) to simulate the current canopy carbon dioxide exchange of a heterogeneous tundra ecosystem in European Russia. For the parameterization, we used data obtained from in situ leaf level measurements...... in combination with meteorological data from 2008. The modeled CO2 fluxes were compared with net ecosystem exchange (NEE), measured by the eddy covariance technique during the snow-free period in 2008. The findings from this study indicated that the main state parameters of the exchange processes were leaf area...

  14. Inverse modeling of fossil fuel CO2 emissions at urban scale using OCO-2 retrievals of total column CO2

    Science.gov (United States)

    Ye, X.; Lauvaux, T.; Kort, E. A.; Lin, J. C.; Oda, T.; Yang, E.; Wu, D.

    2016-12-01

    Rapid economic development has given rise to a steady increase of global carbon emissions, which have accumulated in the atmosphere for the past 200 years. Urbanization has concentrated about 70% of the global fossil-fuel CO2 emissions in large metropolitan areas distributed around the world, which represents the most significant anthropogenic contribution to climate change. However, highly uncertain quantifications of urban CO2 emissions are commonplace for numerous cities because of poorly-documented inventories of energy consumption. Therefore, accurate estimates of carbon emissions from global observing systems are a necessity if mitigation strategies are meant to be implemented at global scales. Space-based observations of total column averaged CO2 concentration (XCO2) provide a very promising and powerful tool to quantify urban CO2 fluxes. For the first time, measurements from the Orbiting Carbon Observatory 2 (OCO-2) mission are assimilated in a high resolution inverse modeling system to quantify fossil-fuel CO2 emissions of multiple cities around the globe. The Open-source Data Inventory for Anthropogenic CO2 (ODIAC) emission inventory is employed as a first guess, while the atmospheric transport is simulated using the WRF-Chem model at 1-km resolution. Emission detection and quantification is performed with an Ensemble Kalman Filter method. We demonstrate here the potential of the inverse approach for assimilating thousands of OCO-2 retrievals along tracks near metropolitan areas. We present the detection potential of the system with real-case applications near power plants and present inverse emissions using actual OCO-2 measurements on various urban landscapes. Finally, we will discuss the potential of OCO-2-like satellite instruments for monitoring temporal variations of fossil-fuel CO2 emissions over multiple years, which can provide valuable insights for future satellite observation strategies.

  15. Coupled Stochastic Time-Inverted Lagrangian Transport/Weather Forecast and Research/Vegetation Photosynthesis and Respiration Model. Part II; Simulations of Tower-Based and Airborne CO2 Measurements

    Science.gov (United States)

    Eluszkiewicz, Janusz; Nehrkorn, Thomas; Wofsy, Steven C.; Matross, Daniel; Gerbig, Christoph; Lin, John C.; Freitas, Saulo; Longo, Marcos; Andrews, Arlyn E.; Peters, Wouter

    2007-01-01

    This paper evaluates simulations of atmospheric CO2 measured in 2004 at continental surface and airborne receptors, intended to test the capability to use data with high temporal and spatial resolution for analyses of carbon sources and sinks at regional and continental scales. The simulations were performed using the Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by the Weather Forecast and Research (WRF) model, and linked to surface fluxes from the satellite-driven Vegetation Photosynthesis and Respiration Model (VPRM). The simulations provide detailed representations of hourly CO2 tower data and reproduce the shapes of airborne vertical profiles with high fidelity. WRF meteorology gives superior model performance compared with standard meteorological products, and the impact of including WRF convective mass fluxes in the STILT trajectory calculations is significant in individual cases. Important biases in the simulation are associated with the nighttime CO2 build-up and subsequent morning transition to convective conditions, and with errors in the advected lateral boundary condition. Comparison of STILT simulations driven by the WRF model against those driven by the Brazilian variant of the Regional Atmospheric Modeling System (BRAMS) shows that model-to-model differences are smaller than between an individual transport model and observations, pointing to systematic errors in the simulated transport. Future developments in the WRF model s data assimilation capabilities, basic research into the fundamental aspects of trajectory calculations, and intercomparison studies involving other transport models, are possible venues for reducing these errors. Overall, the STILT/WRF/VPRM offers a powerful tool for continental and regional scale carbon flux estimates.

  16. High-resolution global CO2 modeling: a comparison to GOSAT column CO2 retrievals

    Science.gov (United States)

    Baker, D. F.

    2010-12-01

    Over a year’s worth of column CO2 concentrations retrieved by the Japanese Greenhouse-gases Observing Satellite (GOSAT) are now available: with a global distribution and good sensitivity down to the surface, these data could provide an important new view of the functioning of the global carbon cycle. The retrievals seem to be corrupted by systematic errors with a magnitude of several ppm, however; to be truly useful, these biases must be greatly reduced before being used in atmospheric transport inversions. Here GOSAT column CO2 retrievals are compared to values from a high-resolution global atmospheric transport model; the residuals are correlated with a variety of factors (including aerosol optical depth, cloud coverage, surface type, and viewing geometry) globally, across a full year of data, to help identify systematic errors in the retrievals and attribute them to possible causes. This broad comparison to model data is meant to complement the comparison to in situ CO2 measurements and upward-looking Fourier spectrometer data currently being used to validate the retrievals at a relatively few times and locations. NASA’s GEOS5 analyzed meteorology products at 0.5° x 0.67° resolution (lat/lon) are used both to compute diurnally-varying land biospheric fluxes (with the SiB model) and to transport these fluxes through the atmosphere with the off-line PCTM model (40 vertical layers, also at 0.5° x 0.67°). Global fossil fuel fluxes with similarly-high spatial resolution, but low temporal resolution, plus monthly varying air-sea fluxes from an ocean model, are also transported. The net fluxes and CO2 fields are optimized at coarse scales in a Transcom-like time-dependent inversion to agree with data from the in situ CO2 measurement network before the GOSAT comparison is made.

  17. Large Eddy Simulation of Supercritical CO2 Through Bend Pipes

    Science.gov (United States)

    He, Xiaoliang; Apte, Sourabh; Dogan, Omer

    2017-11-01

    Supercritical Carbon Dioxide (sCO2) is investigated as working fluid for power generation in thermal solar, fossil energy and nuclear power plants at high pressures. Severe erosion has been observed in the sCO2 test loops, particularly in nozzles, turbine blades and pipe bends. It is hypothesized that complex flow features such as flow separation and property variations may lead to large oscillations in the wall shear stresses and result in material erosion. In this work, large eddy simulations are conducted at different Reynolds numbers (5000, 27,000 and 50,000) to investigate the effect of heat transfer in a 90 degree bend pipe with unit radius of curvature in order to identify the potential causes of the erosion. The simulation is first performed without heat transfer to validate the flow solver against available experimental and computational studies. Mean flow statistics, turbulent kinetic energy, shear stresses and wall force spectra are computed and compared with available experimental data. Formation of counter-rotating vortices, named Dean vortices, are observed. Secondary flow pattern and swirling-switching flow motions are identified and visualized. Effects of heat transfer on these flow phenomena are then investigated by applying a constant heat flux at the wall. DOE Fossil Energy Crosscutting Technology Research Program.

  18. A model for estimating CO2 solubility in aqueous alkanolamines

    DEFF Research Database (Denmark)

    Gabrielsen, Jostein; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2005-01-01

    Partial pressures of carbon dioxide (CO2) over aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) have been correlated using a simple approach where only one chemical equilibrium reaction is taken into account and assuming ideal gas and ideal liquid...... of CO2 over an aqueous alkanolamine solution. Accurate values for the partial pressure of CO2 are obtained for a limited loading, temperature, and pressure range that is useful in modeling CO2 capture from coal-fired power plants. Heat of absorption values derived from the model agree with experimental...

  19. Simulated 21st century's increase in oceanic suboxia by CO2-enhanced biotic carbon export

    Science.gov (United States)

    Oschlies, Andreas; Schulz, Kai G.; Riebesell, Ulf; Schmittner, Andreas

    2008-12-01

    The primary impacts of anthropogenic CO2 emissions on marine biogeochemical cycles predicted so far include ocean acidification, global warming induced shifts in biogeographical provinces, and a possible negative feedback on atmospheric CO2 levels by CO2-fertilized biological production. Here we report a new potentially significant impact on the oxygen-minimum zones of the tropical oceans. Using a model of global climate, ocean circulation, and biogeochemical cycling, we extrapolate mesocosm-derived experimental findings of a pCO2-sensitive increase in biotic carbon-to-nitrogen drawdown to the global ocean. For a simulation run from the onset of the industrial revolution until A.D. 2100 under a "business-as-usual" scenario for anthropogenic CO2 emissions, our model predicts a negative feedback on atmospheric CO2 levels, which amounts to 34 Gt C by the end of this century. While this represents a small alteration of the anthropogenic perturbation of the carbon cycle, the model results reveal a dramatic 50% increase in the suboxic water volume by the end of this century in response to the respiration of excess organic carbon formed at higher CO2 levels. This is a significant expansion of the marine "dead zones" with severe implications not only for all higher life forms but also for oxygen-sensitive nutrient recycling and, hence, for oceanic nutrient inventories.

  20. Numerical simulation of CO2 separation from gas mixtures in membrane modules: Effect of chemical absorbent

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Reza Razavi

    2016-01-01

    Full Text Available In this study, a mathematical model is proposed for prediction of CO2 absorption from N2/CO2 mixture by potassium threonate in a hollow-fiber membrane contactor (HFMC. CFD technique using numerical method of finite element was applied to solve the governing equations of model. Effect of different factors on CO2 absorption was analyzed and for investigation of absorbent type effect, functioning of potassium threonate was compared with diethanolamine (DEA. Axial and radial diffusion can be described with the two dimensional model established in this work. The obtained simulation results were compared with the reported experimental data to ensure accuracy of the model predictions. Comparison of model results with experimental data revealed that the developed model can well predict CO2 capture by potassium threonate in HFMCs. Increment of absorbent flow rate and concentration eventuate in enhancement of CO2 absorption. On the other hand, capture of CO2 will be reduced with increment of gas flow rate. According to the model results, potassium threonate can be considered as a more efficient absorbent as compared with DEA.

  1. Causes of variation among rice models in yield response to CO2 examined with Free-Air CO2 Enrichment and growth chamber experiments.

    Science.gov (United States)

    Hasegawa, Toshihiro; Li, Tao; Yin, Xinyou; Zhu, Yan; Boote, Kenneth; Baker, Jeffrey; Bregaglio, Simone; Buis, Samuel; Confalonieri, Roberto; Fugice, Job; Fumoto, Tamon; Gaydon, Donald; Kumar, Soora Naresh; Lafarge, Tanguy; Marcaida Iii, Manuel; Masutomi, Yuji; Nakagawa, Hiroshi; Oriol, Philippe; Ruget, Françoise; Singh, Upendra; Tang, Liang; Tao, Fulu; Wakatsuki, Hitomi; Wallach, Daniel; Wang, Yulong; Wilson, Lloyd Ted; Yang, Lianxin; Yang, Yubin; Yoshida, Hiroe; Zhang, Zhao; Zhu, Jianguo

    2017-11-01

    The CO 2 fertilization effect is a major source of uncertainty in crop models for future yield forecasts, but coordinated efforts to determine the mechanisms of this uncertainty have been lacking. Here, we studied causes of uncertainty among 16 crop models in predicting rice yield in response to elevated [CO 2 ] (E-[CO 2 ]) by comparison to free-air CO 2 enrichment (FACE) and chamber experiments. The model ensemble reproduced the experimental results well. However, yield prediction in response to E-[CO 2 ] varied significantly among the rice models. The variation was not random: models that overestimated at one experiment simulated greater yield enhancements at the others. The variation was not associated with model structure or magnitude of photosynthetic response to E-[CO 2 ] but was significantly associated with the predictions of leaf area. This suggests that modelled secondary effects of E-[CO 2 ] on morphological development, primarily leaf area, are the sources of model uncertainty. Rice morphological development is conservative to carbon acquisition. Uncertainty will be reduced by incorporating this conservative nature of the morphological response to E-[CO 2 ] into the models. Nitrogen levels, particularly under limited situations, make the prediction more uncertain. Improving models to account for [CO 2 ] × N interactions is necessary to better evaluate management practices under climate change.

  2. Importance of crop varieties and management practices: evaluation of a process-based model for simulating CO2 and H2O fluxes at five European maize (Zea mays L.) sites

    Science.gov (United States)

    Li, L.; Vuichard, N.; Viovy, N.; Ciais, P.; Wang, T.; Ceschia, E.; Jans, W.; Wattenbach, M.; Béziat, P.; Gruenwald, T.; Lehuger, S.; Bernhofer, C.

    2011-06-01

    This paper is a modelling study of crop management impacts on carbon and water fluxes at a range of European sites. The model is a crop growth model (STICS) coupled with a process-based land surface model (ORCHIDEE). The data are online eddy-covariance observations of CO2 and H2O fluxes at five European maize cultivation sites. The results show that the ORCHIDEE-STICS model explains up to 75 % of the observed daily net CO2 ecosystem exchange (NEE) variance, and up to 79 % of the latent heat flux (LE) variance at five sites. The model is better able to reproduce gross primary production (GPP) variations than terrestrial ecosystem respiration (TER) variations. We conclude that structural deficiencies in the model parameterizations of leaf area index (LAI) and TER are the main sources of error in simulating CO2 and H2O fluxes. A number of sensitivity tests, with variable crop variety, nitrogen fertilization, irrigation, and planting date, indicate that any of these management factors is able to change NEE by more than 15 %, but that the response of NEE to management parameters is highly site-dependent. Changes in management parameters are found to impact not only the daily values of NEE and LE, but also the cumulative yearly values. In addition, LE is shown to be less sensitive to management parameters than NEE. Multi-site model evaluations, coupled with sensitivity analysis to management parameters, thus provide important information about model errors, which helps to improve the simulation of CO2 and H2O fluxes across European croplands.

  3. Importance of crop varieties and management practices: evaluation of a process-based model for simulating CO2 and H2O fluxes at five European maize (Zea mays L. sites

    Directory of Open Access Journals (Sweden)

    T. Gruenwald

    2011-06-01

    Full Text Available This paper is a modelling study of crop management impacts on carbon and water fluxes at a range of European sites. The model is a crop growth model (STICS coupled with a process-based land surface model (ORCHIDEE. The data are online eddy-covariance observations of CO2 and H2O fluxes at five European maize cultivation sites. The results show that the ORCHIDEE-STICS model explains up to 75 % of the observed daily net CO2 ecosystem exchange (NEE variance, and up to 79 % of the latent heat flux (LE variance at five sites. The model is better able to reproduce gross primary production (GPP variations than terrestrial ecosystem respiration (TER variations. We conclude that structural deficiencies in the model parameterizations of leaf area index (LAI and TER are the main sources of error in simulating CO2 and H2O fluxes. A number of sensitivity tests, with variable crop variety, nitrogen fertilization, irrigation, and planting date, indicate that any of these management factors is able to change NEE by more than 15 %, but that the response of NEE to management parameters is highly site-dependent. Changes in management parameters are found to impact not only the daily values of NEE and LE, but also the cumulative yearly values. In addition, LE is shown to be less sensitive to management parameters than NEE. Multi-site model evaluations, coupled with sensitivity analysis to management parameters, thus provide important information about model errors, which helps to improve the simulation of CO2 and H2O fluxes across European croplands.

  4. A fast and robust TOUGH2 module to simulate geological CO2 storage in saline aquifers

    Science.gov (United States)

    Shabani, Babak; Vilcáez, Javier

    2018-02-01

    A new TOUGH2 module to simulate geological CO2 storage (GCS) in saline aquifers is developed based on the widely employed ECO2N module of TOUGH2. The newly developed TOUGH2 module uses a new non-iterative fugacity-activity thermodynamic model to obtain the partitioning of CO2 and H2O between the aqueous and gas phases. Simple but robust thermophysical correlations are used to obtain density, viscosity, and enthalpy of the gas phase. The implementation and accuracy of the employed thermophysical correlations are verified by comparisons against the national institute of standards and technology (NIST) online thermophysical database. To assess the computation accuracy and efficiency, simulation results obtained with the new TOUGH2 module for a one-dimensional non-isothermal radial and a three-dimensional isothermal system are compared against the simulation results obtained with the ECO2N module. Treating salt mass fraction in the aqueous phase as a constant, along with the inclusion of a non-iterative fugacity-activity thermodynamic model, and simple thermophysical correlations, resulted in simulations much faster than simulations with ECO2N module, without losing numerical accuracy. Both modules yield virtually identical results. Additional field-scale simulations of CO2 injection into an actual non-isothermal and heterogeneous geological formation confirmed that the new module is much faster than the ECO2N module in simulating complex field-scale conditions. Owing to its capability to handle CO2-CH4-H2S-N2 gas mixtures and its compatibility with TOUGHREACT, this new TOUGH2 module offers the possibility of developing a fast and robust TOUGHREACT module to predict the fate of CO2 in GCS sites under biotic conditions where CO2, CH4, H2S, and N2 gases can be formed.

  5. Impact of the use of a CO2 responsive land surface model in simulating the effect of climate change on the hydrology of French Mediterranean basins

    Science.gov (United States)

    Queguiner, S.; Martin, E.; Lafont, S.; Calvet, J.-C.; Faroux, S.; Quintana-Seguí, P.

    2011-10-01

    In order to evaluate the uncertainty associated with the impact model in climate change studies, a CO2 responsive version of the land surface model ISBA (ISBA-A-gs) is compared with its standard version in a climate impact assessment study. The study is performed over the French Mediterranean basin using the Safran-Isba-Modcou chain. A downscaled A2 regional climate scenario is used to force both versions of ISBA, and the results of the two land surface models are compared for the present climate and for that at the end of the century. Reasonable agreement is found between models and with discharge observations. However, ISBA-A-gs has a lower mean evapotranspiration and a higher discharge than ISBA-Standard. Results for the impact of climate change are coherent on a yearly basis for evapotranspiration, total runoff, and discharge. However, the two versions of ISBA present contrasting seasonal variations. ISBA-A-gs develops a different vegetation cycle. The growth of the vegetation begins earlier and reaches a slightly lower maximum than in the present climate. This maximum is followed by a rapid decrease in summertime. In consequence, the springtime evapotranspiration is significantly increased when compared to ISBA-Standard, while the autumn evapotranspiration is lower. On average, discharge changes are more significant at the regional scale with ISBA-A-gs.

  6. Simulated changes in aridity from the last glacial maximum to 4xCO2

    Science.gov (United States)

    Greve, Peter; Roderick, Michael L.; Seneviratne, Sonia I.

    2017-11-01

    Aridity is generally defined as the ‘degree to which a climate lacks moisture to sustain life in terrestrial ecosystems’. Several recent studies using the ‘aridity index’ (the ratio of potential evaporation to precipitation), have concluded that aridity will increase with CO2 because of increasing temperature. However, the ‘aridity index’ is—counterintuitively—not a direct measure of aridity per se (when defined as above) and there is widespread evidence that contradicts the ‘warmer is more arid’ interpretation. We provide here an assessment of multi-model changes in a broad set of aridity metrics over a large range of atmospheric CO2 concentrations ranging from conditions at the last glacial maximum to 4xCO2, using an ensemble of simulations from state-of-the-art Earth system models. Most measures of aridity do not show increasing aridity on global scales under conditions of increasing atmospheric CO2 concentrations and related global warming, although we note some varying responses depending on the considered variables. The response is, furthermore, more nuanced at regional scales, but in the majority of regions aridity does not increase with CO2 in the majority of metrics. Our results emphasize that it is not the climate models that project overwhelming increases of aridity with increasing CO2, but rather a secondary, offline, impact model—the ‘aridity index’—that uses climate model output as input.

  7. Sensitivity of CO2 Simulation in a GCM to the Convective Transport Algorithms

    Science.gov (United States)

    Zhu, Z.; Pawson, S.; Collatz, G. J.; Gregg, W. W.; Kawa, S. R.; Baker, D.; Ott, L.

    2014-01-01

    Convection plays an important role in the transport of heat, moisture and trace gases. In this study, we simulated CO2 concentrations with an atmospheric general circulation model (GCM). Three different convective transport algorithms were used. One is a modified Arakawa-Shubert scheme that was native to the GCM; two others used in two off-line chemical transport models (CTMs) were added to the GCM here for comparison purposes. Advanced CO2 surfaced fluxes were used for the simulations. The results were compared to a large quantity of CO2 observation data. We find that the simulation results are sensitive to the convective transport algorithms. Overall, the three simulations are quite realistic and similar to each other in the remote marine regions, but are significantly different in some land regions with strong fluxes such as Amazon and Siberia during the convection seasons. Large biases against CO2 measurements are found in these regions in the control run, which uses the original GCM. The simulation with the simple diffusive algorithm is better. The difference of the two simulations is related to the very different convective transport speed.

  8. Simulation Studies for a Space-Based CO2 Lidar Mission

    Science.gov (United States)

    Kawa, S. R.; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun, X.; Weaver, C. J.

    2010-01-01

    We report results of initial space mission simulation studies for a laser-based, atmospheric CO2 sounder, which are based on real-time carbon cycle process modelling and data analysis. The mission concept corresponds to the Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) recommended by the US National Academy of Sciences' Decadal Survey. As a pre-requisite for meaningful quantitative evaluation, we employ a CO2 model that has representative spatial and temporal gradients across a wide range of scales. In addition, a relatively complete description of the atmospheric and surface state is obtained from meteorological data assimilation and satellite measurements. We use radiative transfer calculations, an instrument model with representative errors and a simple retrieval approach to quantify errors in 'measured' CO2 distributions, which are a function of mission and instrument design specifications along with the atmospheric/surface state. Uncertainty estimates based on the current instrument design point indicate that a CO2 laser sounder can provide data consistent with ASCENDS requirements and will significantly enhance our ability to address carbon cycle science questions. Test of a dawn/dusk orbit deployment, however, shows that diurnal differences in CO2 column abundance, indicative of plant photosynthesis and respiration fluxes, will be difficult to detect

  9. Absorber Model for CO2 Capture by Monoethanolamine

    DEFF Research Database (Denmark)

    Faramarzi, Leila; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2010-01-01

    The rate-based steady-state model proposed by Gabrielsen et al. (Gabrielsen, J.; Michelsen, M. L.; Kontogeorgis, G. M.; Stenby, E. H. AIChE J. 2006, 52, 10, 3443-3451) for the design of the CO2-2-amino-2-methylpropanol absorbers is adopted and improved for the design of the CO2-monoethanolamine......, and their impact on the model's prediction is compared. The model has been successfully applied to CO2 absorber packed columns and validated against pilot plant data with good agreement....

  10. CO2-Brine Displacement in Geological CO2 Sequestration: Microfluidic Flow Model Study

    Science.gov (United States)

    Cao, S. C.; Jung, J.

    2014-12-01

    Geological CO2 sequestration is a promising method to reduce atmospheric CO2 and deep saline aquifers is one of the most important options due to their capacity for CO2 storage. Thus, a better understanding of two immiscible brine-CO2 mobility and its saturation, including invading patterns in deep saline aquifers as CO2 storage sites is required. Lenormand (1990) explored the invading patterns of two immiscible fluids in porous media with a transition region and three dominant regions: capillary fingering, viscous fingering, and stable displacement. These are determined by two main aspect ratios Nm and Nc through experimental studies using micromodel. Micromodel provides the opportunity to discover unrecognized processes, and test existing theories and assumptions in fluid flow through porous media. In this study, the micromodel was used to explore the effects of the scCO2 injecting velocity and ionic strength on invading patterns in geological CO2 sequestration. When scCO2 was injected into the micromodel that has already saturated with brine, the brine in the micromodel was displaced by injected scCO2. Continuous scCO2 injection into the micromodel leaded the scCO2 to pass through the micromodel. And the scCO2-brine displacement distribution in the micromodel remained constant during additional 100 PV scCO2 injection after injecting scCO2 passed through micromodel. When scCO2 passed through the porous media, the scCO2-brine displacement distribution represented the maximum displacement ratio. Results showed that scCO2-brine displacement ratios increased with: elevated pressures in the range of 3MPa~8MPa, decreased ionic strength from 5M to 1M NaCl, and increased scCO2 injecting velocity up to 40 μL/min. Also, Nm and Nc obtained in this study are located in transition region of the invading patterns suggested by Lenormand (1990).

  11. Numerical Simulation and Analysis of CO2 Removal in a Polypropylene Hollow Fiber Membrane Contactor

    Directory of Open Access Journals (Sweden)

    Zhien Zhang

    2014-01-01

    Full Text Available This present study shows a comprehensive 2D numerical model for removal of CO2 in a polypropylene (PP hollow fiber membrane contactor (HFMC using the computational fluid dynamics (CFD method. Monoethanolamine (MEA solution was used as the liquid absorbent in a nonwetting mode. The simulation results represented that higher liquid velocity and concentration and lower gas velocity and concentration led to higher percent of CO2 removal. The most proper parameters for CO2 removal were less than 1 mol m−3 gas concentration and 0.2 m s−1 gas flow rate, and for MEA the values were above 8 mol m−3 concentration and approximately 1 m s−1 liquid velocity. Furthermore, the model was validated with the experiment results. Therefore, the modeling results provided references to the selection of absorbents and operation parameters in the experimental study and pilot-scale applications.

  12. An empirical model of H2O, CO2 and CO coma distributions and production rates for comet 67P/Churyumov-Gerasimenko based on ROSINA/DFMS measurements and AMPS-DSMC simulations

    Science.gov (United States)

    Hansen, Kenneth C.; Altwegg, Kathrin; Bieler, Andre; Berthelier, Jean-Jacques; Calmonte, Ursina; Combi, Michael R.; De Keyser, Johan; Fiethe, Björn; Fougere, Nicolas; Fuselier, Stephen; Gombosi, T. I.; Hässig, Myrtha; Huang, Zhenguang; Le Roy, Léna; Rubin, Martin; Tenishev, Valeriy; Toth, Gabor; Tzou, Chia-Yu; ROSINA Team

    2016-10-01

    We have previously used results from the AMPS DSMC (Adaptive Mesh Particle Simulator Direct Simulation Monte Carlo) model to create an empirical model of the near comet water (H2O) coma of comet 67P/Churyumov-Gerasimenko. In this work we create additional empirical models for the coma distributions of CO2 and CO. The AMPS simulations are based on ROSINA DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, Double Focusing Mass Spectrometer) data taken over the entire timespan of the Rosetta mission. The empirical model is created using AMPS DSMC results which are extracted from simulations at a range of radial distances, rotation phases and heliocentric distances. The simulation results are then averaged over a comet rotation and fitted to an empirical model distribution. Model coefficients are then fitted to piecewise-linear functions of heliocentric distance. The final product is an empirical model of the coma distribution which is a function of heliocentric distance, radial distance, and sun-fixed longitude and latitude angles. The model clearly mimics the behavior of water shifting production from North to South across the inbound equinox while the CO2 production is always in the South.The empirical model can be used to de-trend the spacecraft motion from the ROSINA COPS and DFMS data. The ROSINA instrument measures the neutral coma density at a single point and the measured value is influenced by the location of the spacecraft relative to the comet and the comet-sun line. Using the empirical coma model we can correct for the position of the spacecraft and compute a total production rate based on single point measurements. In this presentation we will present the coma production rates as a function of heliocentric distance for the entire Rosetta mission.This work was supported by contracts JPL#1266313 and JPL#1266314 from the US Rosetta Project and NASA grant NNX14AG84G from the Planetary Atmospheres Program.

  13. Evaluation of Deep Learning Models for Predicting CO2 Flux

    Science.gov (United States)

    Halem, M.; Nguyen, P.; Frankel, D.

    2017-12-01

    Artificial neural networks have been employed to calculate surface flux measurements from station data because they are able to fit highly nonlinear relations between input and output variables without knowing the detail relationships between the variables. However, the accuracy in performing neural net estimates of CO2 flux from observations of CO2 and other atmospheric variables is influenced by the architecture of the neural model, the availability, and complexity of interactions between physical variables such as wind, temperature, and indirect variables like latent heat, and sensible heat, etc. We evaluate two deep learning models, feed forward and recurrent neural network models to learn how they each respond to the physical measurements, time dependency of the measurements of CO2 concentration, humidity, pressure, temperature, wind speed etc. for predicting the CO2 flux. In this paper, we focus on a) building neural network models for estimating CO2 flux based on DOE data from tower Atmospheric Radiation Measurement data; b) evaluating the impact of choosing the surface variables and model hyper-parameters on the accuracy and predictions of surface flux; c) assessing the applicability of the neural network models on estimate CO2 flux by using OCO-2 satellite data; d) studying the efficiency of using GPU-acceleration for neural network performance using IBM Power AI deep learning software and packages on IBM Minsky system.

  14. CO2 and the hydrologic cycle: Simulation of two Texas river basins

    International Nuclear Information System (INIS)

    King, K.W.; Srinivasan, R.; Arnold, J.G.; Williams, J.R.

    1994-01-01

    Increasing concentrations of CO 2 , in the atmosphere have been speculated to have a major effect on water supplies as well as other ecological characteristics. SWAT (Soil Water Assessment Tool) is a river basin scale hydrologic model that was modified to simulate the impact of CO 2 concentration on ET and biomass production. The model was utilized to analyze the impact of global climate change on two contrasting Texas basins. Climatic changes included doubling of CO 2 concentration from 330 ppm to 660 ppm and varying temperatures 0, ±2, and ±4 C from present values. Potential impacts of six hydrologic parameters including ET, potential ET, water yield, water stress, soil water, and biomass were simulated. CO 2 doubling had a more pronounced effect than did temperature variances. When temperature alone was varied, water yield at the outlet of the basins ranged from -4.4% to 6.5% for basin 1202 and from 2.9% to 26.7% for basin 1208. But, when coupled with an elevated CO 2 concentration, water yields increased in the range of 13.1% to 24.5% for basin 1202 and 5.6% to 33.7% for basin 1208. Rising CO 2 levels reduced ET for both basins, representing an enhanced water use efficiency. Seasonal fluctuations of soil water were a result of different growing periods and are evident from water stress encountered by the plant. With enriched CO 2 levels, increases in biomass production ranged from 6.9% to 47.4% and from 14.5 % to 31.4% for basins 1202 and 1208, respectively. 42 refs., 10 figs., 2 tabs

  15. Modeling Atmospheric CO2 Processes to Constrain the Missing Sink

    Science.gov (United States)

    Kawa, S. R.; Denning, A. S.; Erickson, D. J.; Collatz, J. C.; Pawson, S.

    2005-01-01

    We report on a NASA supported modeling effort to reduce uncertainty in carbon cycle processes that create the so-called missing sink of atmospheric CO2. Our overall objective is to improve characterization of CO2 source/sink processes globally with improved formulations for atmospheric transport, terrestrial uptake and release, biomass and fossil fuel burning, and observational data analysis. The motivation for this study follows from the perspective that progress in determining CO2 sources and sinks beyond the current state of the art will rely on utilization of more extensive and intensive CO2 and related observations including those from satellite remote sensing. The major components of this effort are: 1) Continued development of the chemistry and transport model using analyzed meteorological fields from the Goddard Global Modeling and Assimilation Office, with comparison to real time data in both forward and inverse modes; 2) An advanced biosphere model, constrained by remote sensing data, coupled to the global transport model to produce distributions of CO2 fluxes and concentrations that are consistent with actual meteorological variability; 3) Improved remote sensing estimates for biomass burning emission fluxes to better characterize interannual variability in the atmospheric CO2 budget and to better constrain the land use change source; 4) Evaluating the impact of temporally resolved fossil fuel emission distributions on atmospheric CO2 gradients and variability. 5) Testing the impact of existing and planned remote sensing data sources (e.g., AIRS, MODIS, OCO) on inference of CO2 sources and sinks, and use the model to help establish measurement requirements for future remote sensing instruments. The results will help to prepare for the use of OCO and other satellite data in a multi-disciplinary carbon data assimilation system for analysis and prediction of carbon cycle changes and carbodclimate interactions.

  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

  17. System-level modeling for economic evaluation of geological CO2 storage in gas reservoirs

    International Nuclear Information System (INIS)

    Zhang, Yingqi; Oldenburg, Curtis M.; Finsterle, Stefan; Bodvarsson, Gudmundur S.

    2007-01-01

    One way to reduce the effects of anthropogenic greenhouse gases on climate is to inject carbon dioxide (CO 2 ) from industrial sources into deep geological formations such as brine aquifers or depleted oil or gas reservoirs. Research is being conducted to improve understanding of factors affecting particular aspects of geological CO 2 storage (such as storage performance, storage capacity, and health, safety and environmental (HSE) issues) as well as to lower the cost of CO 2 capture and related processes. However, there has been less emphasis to date on system-level analyses of geological CO 2 storage that consider geological, economic, and environmental issues by linking detailed process models to representations of engineering components and associated economic models. The objective of this study is to develop a system-level model for geological CO 2 storage, including CO 2 capture and separation, compression, pipeline transportation to the storage site, and CO 2 injection. Within our system model we are incorporating detailed reservoir simulations of CO 2 injection into a gas reservoir and related enhanced production of methane. Potential leakage and associated environmental impacts are also considered. The platform for the system-level model is GoldSim [GoldSim User's Guide. GoldSim Technology Group; 2006, http://www.goldsim.com]. The application of the system model focuses on evaluating the feasibility of carbon sequestration with enhanced gas recovery (CSEGR) in the Rio Vista region of California. The reservoir simulations are performed using a special module of the TOUGH2 simulator, EOS7C, for multicomponent gas mixtures of methane and CO 2 . Using a system-level modeling approach, the economic benefits of enhanced gas recovery can be directly weighed against the costs and benefits of CO 2 injection

  18. Molecular simulations of nitrogen-doped hierarchical carbon adsorbents for post-combustion CO2 capture.

    Science.gov (United States)

    Psarras, Peter; He, Jiajun; Wilcox, Jennifer

    2016-10-19

    A present challenge in the mitigation of anthropogenic CO 2 emissions involves the design of less energy- and water-intensive capture technologies. Sorbent-based capture represents a promising solution, as these materials have negligible water requirements and do not incur the heavy energy penalties associated with solvent regeneration. However, to be considered competitive with traditional technologies (i.e., MEA capture), these sorbents must exhibit a high CO 2 loading capacity and high CO 2 /N 2 selectivity. It has been reported that ultramicroporous character and surface nitrogen functionality are of great importance to the enhancement of CO 2 capacity and CO 2 /N 2 selectivity. However, the role of pore size in combination with surface functionality in the enhancement of these properties remains unclear. To investigate these effects, grand canonical Monte Carlo (GCMC) simulations were carried out on pure and N-functionalized 3-layer graphitic slit-pore models and compared to experimental results for two high performing materials reported elsewhere. We show that the quaternary, pyridinic, and especially the oxidized pyridinic group lend to enhanced performance, with the latter providing exceptional CO 2 loading (4.31 mmol g -1 ) and CO 2 /N 2 selectivity (138.3 : 1). Increasing surface nitrogen content resulted in enhanced loading and excellent CO 2 /N 2 selectivity (45.8 : 1-55.9 : 1), provided that the sorbent has significant ultramicroporous character. Additionally, we elucidate a threshold pore width, under which N-functionalization becomes increasingly influential on performance parameters, and show how this threshold changes with application (PC vs. NGCC capture). Finally, we propose that an alternative functionality - the nitroso group - may be responsible for the enhanced performance of some recent materials reported in the literature.

  19. European-wide simulations of croplands using an improved terrestrial biosphere model: 2. Interannual yields and anomalous CO2 fluxes in 2003

    Science.gov (United States)

    Smith, P. C.; Ciais, P.; Peylin, P.; de Noblet-Ducoudré, N.; Viovy, N.; Meurdesoif, Y.; Bondeau, A.

    2010-12-01

    Aiming at producing improved estimates of carbon source/sink spatial and interannual patterns across Europe (35% croplands), this work uses the ORCHIDEE-STICS terrestrial biosphere model including a more realistic representation of croplands, described in part 1 (Smith et al., 2010). Crop yield is derived from annual Net Primary Productivity and compared with wheat and grain maize harvest data for five European countries. Over a 34 year period, the best correlation coefficient obtained between observed and simulated yield time series is for irrigated maize in Italy (R = 0.73). In the data as well as in the model, 1976 and 2003 appear as climate anomalies causing a ≈40% yield drop in the most affected regions. Simulated interannual yield anomalies and the spatial pattern of the yield drop in 2003 are found to be more realistic than the results from ORCHIDEE with no representation of croplands. The simulated 2003 anomalous carbon source from European ecosystems to the atmosphere due to the 2003 summer heat wave is in good agreement with atmospheric inversions (0.20GtC, from May to October). The anomaly is twice too large in the ORCHIDEE alone simulation, owing to the unrealistically high exposure of herbaceous plants to the extreme summer conditions. The mechanisms linking abnormally high summer temperatures, the crop productivity drop, and significant carbon source from European ecosystems in 2003 are discussed. Overall, this study highlights the importance of accounting for the specific phenologies of crops sown both in winter and in spring and for irrigation applied to summer crops in regional/global models of the terrestrial carbon cycle.

  20. Evaluation of CO2 free electricity trading market in Japan by multi-agent simulations

    International Nuclear Information System (INIS)

    Sichao, Kan; Yamamoto, Hiromi; Yamaji, Kenji

    2010-01-01

    As of November 2008, a new market, the CO 2 free electricity market, started pilot trading within the Japan Electric Power Exchange (JEPX). The electricity in this market comes from renewable resources, nuclear or fossil thermal power with CDM credits. The demanders of the CO 2 free electricity are supposed to be the power companies with high emission rates. In this paper, we analyzed the effects of the new market by using a multi-agent based model to simulate the markets. From our simulation results, we found that the demander, under strict CO 2 emission regulations, tends to buy more electricity from the new CO 2 free market even though the price of this market is higher than that of the normal power exchange market. Suppliers with hydro or nuclear power plants only sell their electricity to the CO 2 free market, and suppliers with coal power plants also enter this market (with CDM credits). The media and peak demands in the normal market are met mainly by electricity from LNG power plants. We also compared the results from the multi-agent approach with those from the least-cost planning approach and found that the results of the two methods were similar.

  1. Uncertainty of Wheat Water Use: Simulated Patterns and Sensitivity to Temperature and CO2

    Science.gov (United States)

    Cammarano, Davide; Roetter, Reimund P.; Asseng, Senthold; Ewert, Frank; Wallach, Daniel; Martre, Pierre; Hatfield, Jerry L.; Jones, James W.; Rosenzweig, Cynthia E.; Ruane, Alex C.; hide

    2016-01-01

    Projected global warming and population growth will reduce future water availability for agriculture. Thus, it is essential to increase the efficiency in using water to ensure crop productivity. Quantifying crop water use (WU; i.e. actual evapotranspiration) is a critical step towards this goal. Here, sixteen wheat simulation models were used to quantify sources of model uncertainty and to estimate the relative changes and variability between models for simulated WU, water use efficiency (WUE, WU per unit of grain dry mass produced), transpiration efficiency (Teff, transpiration per kg of unit of grain yield dry mass produced), grain yield, crop transpiration and soil evaporation at increased temperatures and elevated atmospheric carbon dioxide concentrations ([CO2]). The greatest uncertainty in simulating water use, potential evapotranspiration, crop transpiration and soil evaporation was due to differences in how crop transpiration was modelled and accounted for 50 of the total variability among models. The simulation results for the sensitivity to temperature indicated that crop WU will decline with increasing temperature due to reduced growing seasons. The uncertainties in simulated crop WU, and in particularly due to uncertainties in simulating crop transpiration, were greater under conditions of increased temperatures and with high temperatures in combination with elevated atmospheric [CO2] concentrations. Hence the simulation of crop WU, and in particularly crop transpiration under higher temperature, needs to be improved and evaluated with field measurements before models can be used to simulate climate change impacts on future crop water demand.

  2. Molecular simulation study of the competitive adsorption of H2O and CO2 in zeolite 13X.

    Science.gov (United States)

    Joos, Lennart; Swisher, Joseph A; Smit, Berend

    2013-12-23

    The presence of H2O in postcombustion gas streams is an important technical issue for deploying CO2-selective adsorbents. Because of its permanent dipole, H2O can interact strongly with materials where the selectivity for CO2 is a consequence of its quadrupole interacting with charges in the material. We performed molecular simulations to model the adsorption of pure H2O and CO2 as well as H2O/CO2 mixtures in 13X, a popular zeolite for CO2 capture processes that is commercially available. The simulations show that H2O reduces the capacity of these materials for adsorbing CO2 by an order of magnitude and that at the partial pressures of H2O relevant for postcombustion capture, 13X will be essentially saturated with H2O .

  3. Numerical Simulation of CO2 Flooding of Coalbed Methane Considering the Fluid-Solid Coupling Effect.

    Directory of Open Access Journals (Sweden)

    Jianjun Liu

    Full Text Available CO2 flooding of coalbed methane (CO2-ECBM not only stores CO2 underground and reduces greenhouse gas emissions but also enhances the gas production ratio. This coupled process involves multi-phase fluid flow and coal-rock deformation, as well as processes such as competitive gas adsorption and diffusion from the coal matrix into fractures. A dual-porosity medium that consists of a matrix and fractures was built to simulate the flooding process, and a mathematical model was used to consider the competitive adsorption, diffusion and seepage processes and the interaction between flow and deformation. Due to the effects of the initial pressure and the differences in pressure variation during the production process, permeability changes caused by matrix shrinkage were spatially variable in the reservoir. The maximum value of permeability appeared near the production well, and the degree of rebound decreased with increasing distance from the production well.

  4. REDUCING UNCERTAINTIES IN MODEL PREDICTIONS VIA HISTORY MATCHING OF CO2 MIGRATION AND REACTIVE TRANSPORT MODELING OF CO2 FATE AT THE SLEIPNER PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chen

    2015-03-31

    An important question for the Carbon Capture, Storage, and Utility program is “can we adequately predict the CO2 plume migration?” For tracking CO2 plume development, the Sleipner project in the Norwegian North Sea provides more time-lapse seismic monitoring data than any other sites, but significant uncertainties still exist for some of the reservoir parameters. In Part I, we assessed model uncertainties by applying two multi-phase compositional simulators to the Sleipner Benchmark model for the uppermost layer (Layer 9) of the Utsira Sand and calibrated our model against the time-lapsed seismic monitoring data for the site from 1999 to 2010. Approximate match with the observed plume was achieved by introducing lateral permeability anisotropy, adding CH4 into the CO2 stream, and adjusting the reservoir temperatures. Model-predicted gas saturation, CO2 accumulation thickness, and CO2 solubility in brine—none were used as calibration metrics—were all comparable with the interpretations of the seismic data in the literature. In Part II & III, we evaluated the uncertainties of predicted long-term CO2 fate up to 10,000 years, due to uncertain reaction kinetics. Under four scenarios of the kinetic rate laws, the temporal and spatial evolution of CO2 partitioning into the four trapping mechanisms (hydrodynamic/structural, solubility, residual/capillary, and mineral) was simulated with ToughReact, taking into account the CO2-brine-rock reactions and the multi-phase reactive flow and mass transport. Modeling results show that different rate laws for mineral dissolution and precipitation reactions resulted in different predicted amounts of trapped CO2 by carbonate minerals, with scenarios of the conventional linear rate law for feldspar dissolution having twice as much mineral trapping (21% of the injected CO2) as scenarios with a Burch-type or Alekseyev et al.–type rate law for feldspar dissolution (11%). So far, most reactive transport modeling (RTM) studies for

  5. Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6

    Science.gov (United States)

    Graven, Heather; Allison, Colin E.; Etheridge, David M.; Hammer, Samuel; Keeling, Ralph F.; Levin, Ingeborg; Meijer, Harro A. J.; Rubino, Mauro; Tans, Pieter P.; Trudinger, Cathy M.; Vaughn, Bruce H.; White, James W. C.

    2017-12-01

    The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850-2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

  6. Global Modeling of CO2 Discharges with Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Chloe Berenguer

    2014-01-01

    Full Text Available We developed a global model aiming to study discharges in CO2 under various conditions, pertaining to a large spectrum of pressure, absorbed energy, and feeding values. Various physical conditions and form factors have been investigated. The model was applied to a case of radiofrequency discharge and to helicon type devices functioning in low and high feed conditions. In general, main charged species were found to be CO2+ for sufficiently low pressure cases and O− for higher pressure ones, followed by CO2+, CO+, and O2+ in the latter case. Dominant reaction is dissociation of CO2 resulting into CO production. Electronegativity, important for radiofrequency discharges, increases with pressure, arriving up to 3 for high flow rates for absorbed power of 250 W, and diminishes with increasing absorbed power. Model results pertaining to radiofrequency type plasma discharges are found in satisfactory agreement with those available from an existing experiment. Application to low and high flow rates feedings cases of helicon thruster allowed for evaluation of thruster functioning conditions pertaining to absorbed powers from 50 W to 1.8 kW. The model allows for a detailed evaluation of the CO2 potential to be used as propellant in electric propulsion devices.

  7. Experimental observation and numerical simulation of permeability changes in dolomite at CO2 sequestration conditions

    Science.gov (United States)

    Tutolo, B. M.; Luhmann, A. J.; Kong, X.; Saar, M. O.; Seyfried, W. E.

    2013-12-01

    mineral, fluid, and aqueous species equations of state into its structure. Phase equilibria calculations indicate that fluids traveling away from the depressed temperature zone near the injection well may exsolve and precipitate up to 200 cc CO2, 1.45 cc dolomite, and 2.3 cc calcite, per kg, but we use the reactive transport simulator to place more realistic limits on these calculations. The simulations show that thermally-induced CO2 exsolution creates velocity gradients within the modeled domain, leading to increased velocities at lower pressure due to the increasingly gas-like density of CO2. Because dolomite precipitation kinetics strongly depend on temperature, modeled dolomite precipitation effectively concentrates within high temperature regions, while calcite precipitation is predicted to occur over a broader range. Additionally, because the molar volume of dolomite is almost double that of calcite, transporting a low temperature, dolomite-saturated fluid across a thermal gradient can lead to more substantial pore space clogging. We conclude that injecting cool CO2 into geothermally warm reservoirs may substantially alter formation porosity, permeability, and injectivity, and can result in favorable conditions for permanent storage of CO2 as a solid carbonate phase.

  8. Efficient parallel simulation of CO2 geologic sequestration in saline aquifers

    International Nuclear Information System (INIS)

    Zhang, Keni; Doughty, Christine; Wu, Yu-Shu; Pruess, Karsten

    2007-01-01

    An efficient parallel simulator for large-scale, long-term CO2 geologic sequestration in saline aquifers has been developed. The parallel simulator is a three-dimensional, fully implicit model that solves large, sparse linear systems arising from discretization of the partial differential equations for mass and energy balance in porous and fractured media. The simulator is based on the ECO2N module of the TOUGH2code and inherits all the process capabilities of the single-CPU TOUGH2code, including a comprehensive description of the thermodynamics and thermophysical properties of H2O-NaCl- CO2 mixtures, modeling single and/or two-phase isothermal or non-isothermal flow processes, two-phase mixtures, fluid phases appearing or disappearing, as well as salt precipitation or dissolution. The new parallel simulator uses MPI for parallel implementation, the METIS software package for simulation domain partitioning, and the iterative parallel linear solver package Aztec for solving linear equations by multiple processors. In addition, the parallel simulator has been implemented with an efficient communication scheme. Test examples show that a linear or super-linear speedup can be obtained on Linux clusters as well as on supercomputers. Because of the significant improvement in both simulation time and memory requirement, the new simulator provides a powerful tool for tackling larger scale and more complex problems than can be solved by single-CPU codes. A high-resolution simulation example is presented that models buoyant convection, induced by a small increase in brine density caused by dissolution of CO2

  9. The Impact of Prior Biosphere Models in the Inversion of Global Terrestrial CO2 Fluxes by Assimilating OCO-2 Retrievals

    Science.gov (United States)

    Philip, Sajeev; Johnson, Matthew S.

    2018-01-01

    Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emissions and biospheric fluxes. The processes controlling terrestrial biosphere-atmosphere carbon exchange are currently not fully understood, resulting in terrestrial biospheric models having significant differences in the quantification of biospheric CO2 fluxes. Atmospheric transport models assimilating measured (in situ or space-borne) CO2 concentrations to estimate "top-down" fluxes, generally use these biospheric CO2 fluxes as a priori information. Most of the flux inversion estimates result in substantially different spatio-temporal posteriori estimates of regional and global biospheric CO2 fluxes. The Orbiting Carbon Observatory 2 (OCO-2) satellite mission dedicated to accurately measure column CO2 (XCO2) allows for an improved understanding of global biospheric CO2 fluxes. OCO-2 provides much-needed CO2 observations in data-limited regions facilitating better global and regional estimates of "top-down" CO2 fluxes through inversion model simulations. The specific objectives of our research are to: 1) conduct GEOS-Chem 4D-Var assimilation of OCO-2 observations, using several state-of-the-science biospheric CO2 flux models as a priori information, to better constrain terrestrial CO2 fluxes, and 2) quantify the impact of different biospheric model prior fluxes on OCO-2-assimilated a posteriori CO2 flux estimates. Here we present our assessment of the importance of these a priori fluxes by conducting Observing System Simulation Experiments (OSSE) using simulated OCO-2 observations with known "true" fluxes.

  10. Long-term surface pCO2 trends from observations and models

    Directory of Open Access Journals (Sweden)

    Jerry F. Tjiputra

    2014-05-01

    Full Text Available We estimate regional long-term surface ocean pCO2 growth rates using all available underway and bottled biogeochemistry data collected over the past four decades. These observed regional trends are compared with those simulated by five state-of-the-art Earth system models over the historical period. Oceanic pCO2 growth rates faster than the atmospheric growth rates indicate decreasing atmospheric CO2 uptake, while ocean pCO2 growth rates slower than the atmospheric growth rates indicate increasing atmospheric CO2 uptake. Aside from the western subpolar North Pacific and the subtropical North Atlantic, our analysis indicates that the current observation-based basin-scale trends may be underestimated, indicating that more observations are needed to determine the trends in these regions. Encouragingly, good agreement between the simulated and observed pCO2 trends is found when the simulated fields are subsampled with the observational coverage. In agreement with observations, we see that the simulated pCO2 trends are primarily associated with the increase in surface dissolved inorganic carbon (DIC associated with atmospheric carbon uptake, and in part by warming of the sea surface. Under the RCP8.5 future scenario, DIC continues to be the dominant driver of pCO2 trends, with little change in the relative contribution of SST. However, the changes in the hydrological cycle play an increasingly important role. For the contemporary (1970–2011 period, the simulated regional pCO2 trends are lower than the atmospheric growth rate over 90% of the ocean. However, by year 2100 more than 40% of the surface ocean area has a higher oceanic pCO2 trend than the atmosphere, implying a reduction in the atmospheric CO2 uptake rate. The fastest pCO2 growth rates are projected for the subpolar North Atlantic, while the high-latitude Southern Ocean and eastern equatorial Pacific have the weakest growth rates, remaining below the atmospheric pCO2 growth rate. Our work

  11. Numerical simulation of H2S and CO2 generation during SAGD

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Perez, A.; Kamp, A.M. [CHLOE, UFR Science, University of Pau, 64000, Pau (France); Soleimani, H. (IFP School (France)); Darche, G. (TOTAL, Pau (France))

    2011-07-01

    In the heavy oil industry, the steam assisted gravity drainage process is often used to enhance oil recovery but the production of undesirable gases occurs during this process. These gases are mainly hydrogen sulphide and carbon dioxide, generated through chemical reactions triggered by high temperatures and water presence. The aim of this paper is to create a kinetic model for H2S and CO2 generation and to insert it in a reservoir simulation. This model was then tested under steam injection conditions in an SAGD system using experimental data available in the literature. The model developed successfully reproduced gas plateaus at different temperatures and results from the test showed that the model's predicted gas emissions are of the same order of magnitude as the field results. This paper presented a new kinetic model which can predict H2S and CO2 emissions of a SAGD system and could thus be used in the design of treatment facilities.

  12. One-Dimensional Reactive Transport Modeling of CO2 Storage Systems - Change in Cap Rock Porosity Triggered by Pressure and Temperature Dependent CO2-Water-Rock Interactions

    Science.gov (United States)

    Hemme, C.; van Berk, W.

    2015-12-01

    In carbon capture and storage (CCS) systems supercritical CO2 is injected into a reservoir and dissolves in the reservoir brine. Subsequently, CO2(aq) diffuses into the cap rock to regions of lower total pressure and temperature and triggers CO2-water-rock interactions that are coupled with mass transport and result in precipitation and/or dissolution of minerals along the CO2 migration path. Such hydrogeochemical interactions change porosities and are responsible for the improvement or deterioration of the long term integrity of the system. This study presents a semi-generic hydrogeochemical model based on chemical equilibrium thermodynamics, data from several CO2 storage systems, and plausible assumptions regarding non-available data. One-dimensional reactive transport modeling is performed by using the U.S.G.S. PHREEQC code (3.1.4-8929; phreeqc.dat database) to identify and quantify the loss or gain of total porosity affected by hydrogeochemical reactions driven by diffusive mass transport exposed to pressure and temperature gradients. A fine spatial and temporal discretization, the use of non-reactive tracers, and a broad variety of modeling scenarios enable the calculation of the relevant timescale for simulations of long-term storage of CO2 and the consideration of the pressure dependent mass action law constants along the CO2 migration path. Modeling results show that the relevant timescale for simulations of long-term storage of CO2 is in the range of 106 years, and that pressure/temperature conditions, heterogeneities (veins and fractures) and the mineralogical composition of the cap rock have the strongest influence on the increase in cap rock porosity (maximum increase from initial 5 % to 7.5 %). Critical parameter combinations - total pressure effects are crucial - could put long-term integrity at risks. Nevertheless, a wide range of conditions and parameter combinations for safe CO2 storage is identified by other modeling scenarios.

  13. CO2 Capture with Ionic Liquids : Experiments and Molecular Simulations

    NARCIS (Netherlands)

    Ramdin, M.

    2015-01-01

    In this thesis, we investigated the potential of physical ILs for CO2 capture at pre-combustion and natural gas sweetening conditions. The performance of ILs with respect to conventional solvents is assessed in terms of gas solubilities and selectivities. The work discussed in this thesis consists

  14. Application of simplified models to CO2 migration and immobilization in large-scale geological systems

    KAUST Repository

    Gasda, Sarah E.

    2012-07-01

    Long-term stabilization of injected carbon dioxide (CO 2) is an essential component of risk management for geological carbon sequestration operations. However, migration and trapping phenomena are inherently complex, involving processes that act over multiple spatial and temporal scales. One example involves centimeter-scale density instabilities in the dissolved CO 2 region leading to large-scale convective mixing that can be a significant driver for CO 2 dissolution. Another example is the potentially important effect of capillary forces, in addition to buoyancy and viscous forces, on the evolution of mobile CO 2. Local capillary effects lead to a capillary transition zone, or capillary fringe, where both fluids are present in the mobile state. This small-scale effect may have a significant impact on large-scale plume migration as well as long-term residual and dissolution trapping. Computational models that can capture both large and small-scale effects are essential to predict the role of these processes on the long-term storage security of CO 2 sequestration operations. Conventional modeling tools are unable to resolve sufficiently all of these relevant processes when modeling CO 2 migration in large-scale geological systems. Herein, we present a vertically-integrated approach to CO 2 modeling that employs upscaled representations of these subgrid processes. We apply the model to the Johansen formation, a prospective site for sequestration of Norwegian CO 2 emissions, and explore the sensitivity of CO 2 migration and trapping to subscale physics. Model results show the relative importance of different physical processes in large-scale simulations. The ability of models such as this to capture the relevant physical processes at large spatial and temporal scales is important for prediction and analysis of CO 2 storage sites. © 2012 Elsevier Ltd.

  15. The global warming game - simulations of a CO2 reduction agreement

    International Nuclear Information System (INIS)

    Fankhauser, S.; Kverndokk, S.

    1992-06-01

    The paper analyses incentives for and the benefits of a possible international cooperation to reduce CO-2-emissions. The negotiations are modeled as a (static) reciprocal-externality-game in CO 2 -emissions between five world regions. CO 2 -emissions affect the players in two ways: First, each country's income depends (via energy inputs) on the amount of CO 2 emitted. On the other hand, emissions may cause future damage due to climate change. Without cooperation, each player maximizes its net benefits in setting marginal income equal to its marginal damage cost (Nash equilibrium). Under full cooperation marginal income equals the sum of the marginal damages (social optimum). The paper presents simulations of these two equilibria. Compared to the situation where no attention is paid to the greenhouse effect (the business as usual scenario), emission reductions under the Nash equilibrium can be interpreted as incentives for unilateral actions. According to the simulation results, this can only be expected from OECD countries. The results also imply that a socially optimal treaty, while clearly beneficial for the world in its entirety, may only be achieved if side payments are offered to at least China and the former Soviet Union, and probably the USA. The optimal global emission reductions in this study are on average lower than the reductions recommended by international conferences. 34 refs., 2 figs., 9 tabs

  16. Membrane-assisted CO2 liquefaction: performance modelling of CO2 capture from flue gas in cement production

    NARCIS (Netherlands)

    Bouma, R.H.B.; Vercauteren, F.F.; Os, P.J. van; Goetheer, E.L.V.; Berstad, D.; Anantharaman, R.

    2017-01-01

    CEMCAP is an international R&D project under the Horizon 2020 Programme preparing the ground for the large-scale implementation of CO2 capture in the European cement industry. This paper concerns the performance modeling of membraneassisted CO2 liquefaction as a possible retrofit application for

  17. South polar permanent CO2 ice cap presentation in the Global Mars Multiscale Model

    Science.gov (United States)

    Fazel-Rastgar, Farahnaz

    2018-02-01

    The atmospheric influence caused by the Martian permanent south CO2 ice cap is examined to improve the Global Mars Multiscale Model (GM3) to see if it can significantly improve the representation of south polar meteorology. However, the seasonal carbon dioxide ice in the polar regions is presented in the surface ice simulation by the Global Mars Multiscale Model but the model does not produce a permanent south CO2 ice cap, and the physics code must modify to capture the realistic physical such as ice process detail; probably makes a bias in terms of total CO2 ice and meteorological processes in the model aside from ice formation. The permanent south CO2 ice cap in the model can significantly improve the representation of south polar meteorology for example in predicted surface temperatures, surface pressures, horizontal and zonal winds over the south cap and possible initiation of dust storms at south polar region during the southern summer period.

  18. An energy balance perspective on regional CO2-induced temperature changes in CMIP5 models

    OpenAIRE

    Räisänen, Jouni

    2017-01-01

    An energy balance decomposition of temperature changes is conducted for idealized transient CO2-only simulations in the fifth phase of the Coupled Model Intercomparison Project. The multimodel global mean warming is dominated by enhanced clear-sky greenhouse effect due to increased CO2 and water vapour, but other components of the energy balance substantially modify the geographical and seasonal patterns of the change. Changes in the net surface energy flux are important over the oceans, bein...

  19. Modelling the supercritical CO2 extraction kinetics of soybean oil

    Directory of Open Access Journals (Sweden)

    Sandra Svilović

    2015-01-01

    Full Text Available Different empirical models were used to describe the supercritical CO2 extraction of soybean oil obtained at series of operational parameters namely pressure, temperature, solvent flow rate and characteristic particle size. Process yields obtained by supercritical CO2 were up to 19.33%. Several kinetic models: Brunner, Kandiah and Spiro, Tan and Liou, Martinez et al. and Esquivel et al. were used to test the experimental yield data. All models were analysed using nonlinear regression method. Also a new model, modified Esquivel et al., was proposed and analysed using nonlinear regression method as well. According to the obtained results for extraction yield of soybean oil, the modified Esquivel et al. model show the best agreement between experimental and model calculated data.

  20. Modeling CO2 Laser Ablative Impulse with Polymers

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.; Sasoh, Akihiro

    2010-01-01

    Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO 2 laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO 2 laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

  1. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

    % 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....... Until the present study, no area-specific representation had been developed for the surface water pCO2 of the Baltic Sea and Danish inner waters. A surface water monthly climatology was implemented in the mesoscale modelling framework, and further improved with a near coastal climatology for the Danish...... inner waters. In the modelling framework, the heterogeneous land surfaces of Denmark were assessed by means of a detailed land surface classifications map and the inclusion of a high temporal and spatial resolution biosphere model. Available measurements of surface water pCO2, from stationary sites...

  2. Model-dependence of the CO2 threshold for melting the hard Snowball Earth

    Directory of Open Access Journals (Sweden)

    W. R. Peltier

    2011-01-01

    Full Text Available One of the critical issues of the Snowball Earth hypothesis is the CO2 threshold for triggering the deglaciation. Using Community Atmospheric Model version 3.0 (CAM3, we study the problem for the CO2 threshold. Our simulations show large differences from previous results (e.g. Pierrehumbert, 2004, 2005; Le Hir et al., 2007. At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005, but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007. It is found that the difference of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bars of CO2, CAM3 yields 117 Wm−2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005, respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007, but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than that in Pierrehumbert (2005. Effects of pressure broadening and collision-induced absorption are also studied using a radiative-convective model and CAM3. Both effects substantially increase surface temperature and thus lower the CO2 threshold. The radiative-convective model yields a CO2 threshold of about 0.21 bars with surface albedo of 0.663. Without considering the effects of pressure broadening and collision-induced absorption, CAM3 yields an approximate CO2 threshold of about 1.0 bar for surface albedo of about 0.6. However, the threshold is lowered to 0.38 bars as both effects are considered.

  3. An ensemble approach to simulate CO2 emissions from natural fires

    Science.gov (United States)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

    2014-06-01

    This paper presents ensemble simulations with the global climate model developed at the A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). These simulations are forced by historical reconstructions of concentrations of well-mixed greenhouse gases (CO2, CH4, and N2O), sulfate aerosols (both in the troposphere and stratosphere), extent of crops and pastures, and total solar irradiance for AD 850-2005 (hereafter all years are taken as being AD) and by the Representative Concentration Pathway (RCP) scenarios for the same forcing agents until the year 2300. Our model implements GlobFIRM (Global FIRe Model) as a scheme for calculating characteristics of natural fires. Comparing to the original GlobFIRM model, in our implementation, the scheme is extended by a module accounting for CO2 release from soil during fires. The novel approach of our paper is to simulate natural fires in an ensemble fashion. Different ensemble members in the present paper are constructed by varying the values of parameters of the natural fires module. These members are constrained by the GFED-3.1 data set for the burnt area and CO2 release from fires and further subjected to Bayesian averaging. Our simulations are the first coupled model assessment of future changes in gross characteristics of natural fires. In our model, the present-day (1998-2011) global area burnt due to natural fires is (2.1 ± 0.4) × 106 km2 yr-1 (ensemble mean and intra-ensemble standard deviation are presented), and the respective CO2 emissions to the atmosphere are (1.4 ± 0.2) Pg C yr-1. The latter value is in agreement with the corresponding GFED estimates. The area burnt by natural fires is generally larger than the GFED estimates except in boreal Eurasia, where it is realistic, and in Australia, where it is smaller than these estimates. Regionally, the modelled CO2 emissions are larger (smaller) than the GFED estimates in Europe (in the tropics and north-eastern Eurasia). From

  4. Simulation and initial experiments of a high power pulsed TEA CO2 laser

    Science.gov (United States)

    Torabi, R.; Saghafifar, H.; Koushki, A. M.; Ganjovi, A. A.

    2016-01-01

    In this paper, the output characteristics of a UV pin array pre-ionized TEA CO2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.

  5. Simulated anthropogenic CO2 storage and acidification of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    J. Palmiéri

    2015-02-01

    Full Text Available Constraints on the Mediterranean Sea's storage of anthropogenic CO2 are limited, coming only from data-based approaches that disagree by more than a factor of two. Here we simulate this marginal sea's anthropogenic carbon storage by applying a perturbation approach in a high-resolution regional model. Our model simulates that, between 1800 and 2001, basin-wide CO2 storage by the Mediterranean Sea has increased by 1.0 Pg C, a lower limit based on the model's weak deep-water ventilation, as revealed by evaluation with CFC-12. Furthermore, by testing a data-based approach (transit time distribution in our model, comparing simulated anthropogenic CO2 to values computed from simulated CFC-12 and physical variables, we conclude that the associated basin-wide storage of 1.7 Pg, published previously, must be an upper bound. Out of the total simulated storage of 1.0 Pg C, 75% comes from the air–sea flux into the Mediterranean Sea and 25% comes from net transport from the Atlantic across the Strait of Gibraltar. Sensitivity tests indicate that the Mediterranean Sea's higher total alkalinity, relative to the global-ocean mean, enhances the Mediterranean's total inventory of anthropogenic carbon by 10%. Yet the corresponding average anthropogenic change in surface pH does not differ significantly from the global-ocean average, despite higher total alkalinity. In Mediterranean deep waters, the pH change is estimated to be between −0.005 and −0.06 pH units.

  6. Simulated Impact of Glacial Runoff on CO2 Uptake in the Gulf of Alaska

    Science.gov (United States)

    Pilcher, Darren J.; Siedlecki, Samantha A.; Hermann, Albert J.; Coyle, Kenneth O.; Mathis, Jeremy T.; Evans, Wiley

    2018-01-01

    The Gulf of Alaska (GOA) receives substantial summer freshwater runoff from glacial meltwater. The alkalinity of this runoff is highly dependent on the glacial source and can modify the coastal carbon cycle. We use a regional ocean biogeochemical model to simulate CO2 uptake in the GOA under different alkalinity-loading scenarios. The GOA is identified as a current net sink of carbon, though low-alkalinity tidewater glacial runoff suppresses summer coastal carbon uptake. Our model shows that increasing the alkalinity generates an increase in annual CO2 uptake of 1.9-2.7 TgC/yr. This transition is comparable to a projected change in glacial runoff composition (i.e., from tidewater to land-terminating) due to continued climate warming. Our results demonstrate an important local carbon-climate feedback that can significantly increase coastal carbon uptake via enhanced air-sea exchange, with potential implications to the coastal ecosystems in glaciated areas around the world.

  7. A Regional CO2 Observing System Simulation Experiment Using ASCENDS Observations and WRF-STILT Footprints

    Science.gov (United States)

    Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Collatz, G. J.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Aschbrenner, R.; Zaccheo, T.

    2012-12-01

    Knowledge of the spatiotemporal variations in emissions and uptake of CO2 is hampered by sparse measurements. The recent advent of satellite measurements of CO2 concentrations is increasing the density of measurements, and the future mission ASCENDS (Active Sensing of CO2 Emissions over Nights, Days and Seasons) will provide even greater coverage and precision. Lagrangian atmospheric transport models run backward in time can quantify surface influences ("footprints") of diverse measurement platforms and are particularly well suited for inverse estimation of regional surface CO2 fluxes at high resolution based on satellite observations. We utilize the STILT Lagrangian particle dispersion model, driven by WRF meteorological fields at 40-km resolution, in a Bayesian synthesis inversion approach to quantify the ability of ASCENDS column CO2 observations to constrain fluxes at high resolution. This study focuses on land-based biospheric fluxes, whose uncertainties are especially large, in a domain encompassing North America. We present results based on realistic input fields for 2007. Pseudo-observation random errors are estimated from backscatter and optical depth measured by the CALIPSO satellite. We estimate a priori flux uncertainties based on output from the CASA-GFED (v.3) biosphere model and make simple assumptions about spatial and temporal error correlations. WRF-STILT footprints are convolved with candidate vertical weighting functions for ASCENDS. We find that at a horizontal flux resolution of 1 degree x 1 degree, ASCENDS observations are potentially able to reduce average weekly flux uncertainties by 0-8% in July, and 0-0.5% in January (assuming an error of 0.5 ppm at the Railroad Valley reference site). Aggregated to coarser resolutions, e.g. 5 degrees x 5 degrees, the uncertainty reductions are larger and more similar to those estimated in previous satellite data observing system simulation experiments.

  8. Error characterization of CO2 vertical mixing in the atmospheric transport model WRF-VPRM

    Directory of Open Access Journals (Sweden)

    U. Karstens

    2012-03-01

    Full Text Available One of the dominant uncertainties in inverse estimates of regional CO2 surface-atmosphere fluxes is related to model errors in vertical transport within the planetary boundary layer (PBL. In this study we present the results from a synthetic experiment using the atmospheric model WRF-VPRM to realistically simulate transport of CO2 for large parts of the European continent at 10 km spatial resolution. To elucidate the impact of vertical mixing error on modeled CO2 mixing ratios we simulated a month during the growing season (August 2006 with different commonly used parameterizations of the PBL (Mellor-Yamada-Janjić (MYJ and Yonsei-University (YSU scheme. To isolate the effect of transport errors we prescribed the same CO2 surface fluxes for both simulations. Differences in simulated CO2 mixing ratios (model bias were on the order of 3 ppm during daytime with larger values at night. We present a simple method to reduce this bias by 70–80% when the true height of the mixed layer is known.

  9. Atomistic simulation of CO 2 solubility in poly(ethylene oxide) oligomers

    KAUST Repository

    Hong, Bingbing

    2013-10-02

    We have performed atomistic molecular dynamics simulations coupled with thermodynamic integration to obtain the excess chemical potential and pressure-composition phase diagrams for CO2 in poly(ethylene oxide) oligomers. Poly(ethylene oxide) dimethyl ether, CH3O(CH 2CH2O)nCH3 (PEO for short) is a widely applied physical solvent that forms the major organic constituent of a class of novel nanoparticle-based absorbents. Good predictions were obtained for pressure-composition-density relations for CO2 + PEO oligomers (2 ≤ n ≤ 12), using the Potoff force field for PEO [J. Chem. Phys. 136, 044514 (2012)] together with the TraPPE model for CO2 [AIChE J. 47, 1676 (2001)]. Water effects on Henrys constant of CO2 in PEO have also been investigated. Addition of modest amounts of water in PEO produces a relatively small increase in Henrys constant. Dependence of the calculated Henrys constant on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. © 2013 Taylor & Francis.

  10. Experimental versus modelled water use in mature Norway spruce (Picea abies exposed to elevated CO2

    Directory of Open Access Journals (Sweden)

    Sebastian eLeuzinger

    2012-10-01

    Full Text Available Rising levels of atmospheric CO2 have often been reported to reduce plant water use. Such behaviour is also predicted by standard equations relating photosynthesis, stomatal conductance, and atmospheric CO2 concentration, which form the core of global dynamic vegetation models (DGVMs. Here, we provide first results from a free air CO2 enrichment (FACE experiment with naturally growing, mature (35 m Picea abies (L. (Norway spruce and compare them to simulations by the DGVM LPJ-GUESS. We monitored sap flow, stem water deficit, stomatal conductance, leaf water potential and soil moisture in five 35-40 m tall CO2-treated (550 ppm trees over two seasons. Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station. While the model predicted a stable reduction of transpiration of between 9 and 18 % (at concentrations of 550-700ppm atmospheric CO2, the combined evidence from various methods characterising water use in our experimental trees suggest no changes in response to future CO2 concentrations. The discrepancy between the modelled and the experimental results may be a scaling issue: while dynamic vegetation models correctly predict leaf-level responses, they may not sufficiently account for the processes involved at the canopy and ecosystem scale, which could mitigate the first-order stomatal response.

  11. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Kenneth M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2010-09-01

    Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than

  12. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration - Literature Review

    International Nuclear Information System (INIS)

    Krupka, Kenneth M.; Cantrell, Kirk J.; McGrail, B. Peter

    2010-01-01

    Permanent storage of anthropogenic CO 2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO 2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO 2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO 2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO 2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO 2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO 2 sequestration. A review of thermodynamic data for CO 2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO 2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO 2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO 2 and CH 4 gases, carbonate aqueous species, and carbonate minerals. Values of Δ f G 298 o and/or log K r,298 o are available for essentially all of these compounds. However, log K r,T o or heat capacity values at temperatures above 298 K exist

  13. Mission Simulation of Space Lidar Measurements for Seasonal and Regional CO2 Variations

    Science.gov (United States)

    Kawa, Stephan; Collatz, G. J.; Mao, J.; Abshire, J. B.; Sun, X.; Weaver, C. J.

    2010-01-01

    Results of mission simulation studies are presented for a laser-based atmospheric [82 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to the Active Sensing of [82 over Nights, Days, and Seasons (ASCENDS) recommended by the US National Academy of Sciences Decadal Survey of Earth Science and Applications from Space. One prerequisite for meaningful quantitative sensor evaluation is realistic CO2 process modeling across a wide range of scales, i.e., does the model have representative spatial and temporal gradients? Examples of model comparison with data will be shown. Another requirement is a relatively complete description of the atmospheric and surface state, which we have obtained from meteorological data assimilation and satellite measurements from MODIS and [ALIPS0. We use radiative transfer model calculations, an instrument model with representative errors ' and a simple retrieval approach to complete the cycle from "nature" run to "pseudo-data" CO2, Several mission and instrument configuration options are examined/ and the sensitivity to key design variables is shown. We use the simulation framework to demonstrate that within reasonable technological assumptions for the system performance, relatively high measurement precision can be obtained, but errors depend strongly on environmental conditions as well as instrument specifications. Examples are also shown of how the resulting pseudo - measurements might be used to address key carbon cycle science questions.

  14. CO2 Mass transfer model for carbonic anhydrase-enhanced aqueous MDEA solutions

    DEFF Research Database (Denmark)

    Gladis, Arne Berthold; Deslauriers, Maria Gundersen; Neerup, Randi

    2018-01-01

    In this study a CO2 mass transfer model was developed for carbonic anhydrase-enhanced MDEA solutions based on a mechanistic kinetic enzyme model. Four different enzyme models were compared in their ability to predict the liquid side mass transfer coefficient at temperatures in the range of 298...... the SP model is limited to applications with low CO2 partial pressure such as CCS from coal burning power plants. Two other models that were also investigated are not suitable for implementation into an absorber column simulation, as they cannot describe the influence of changing solvent loading...

  15. Modeling CO2 emissions from fossil fuel combustion using the logistic equation

    International Nuclear Information System (INIS)

    Meng, Ming; Niu, Dongxiao

    2011-01-01

    CO 2 emissions from fossil fuel combustion have been known to contribute to the greenhouse effect. Research on emission trends and further forecasting their further values is important for adjusting energy policies, particularly those relative to low carbon. Except for a few countries, the main figures of CO 2 emission from fossil fuel combustion in other countries are S-shaped curves. The logistic function is selected to simulate the S-shaped curve, and to improve the goodness of fit, three algorithms were provided to estimate its parameters. Considering the different emission characteristics of different industries, the three algorithms estimated the parameters of CO 2 emission in each industry separately. The most suitable parameters for each industry are selected based on the criterion of Mean Absolute Percentage Error (MAPE). With the combined simulation values of the selected models, the estimate of total CO 2 emission from fossil fuel combustion is obtained. The empirical analysis of China shows that our method is better than the linear model in terms of goodness of fit and simulation risk. -- Highlights: → Figures of CO 2 emissions from fossil fuel combustion in most countries are S-shape curves. → Using the logistic function to model the S-shape curve. → Three algorithms are offered to estimate the parameters of the logistic function. → The empirical analysis from China shows that the logistic equation has satisfactory simulation results.

  16. Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

    International Nuclear Information System (INIS)

    Roy, Tilla; Bopp, Laurent; Gehlen, Marion; Cadule, Patricia

    2011-01-01

    The increase in atmospheric CO 2 over this century depends on the evolution of the oceanic air-sea CO 2 uptake, which will be driven by the combined response to rising atmospheric CO 2 itself and climate change. Here, the future oceanic CO 2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO 2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO 2 uptake into a CO 2 -induced component, due to rising atmospheric CO 2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO 2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO 2 uptake in the sub-polar Southern Ocean and the equatorial regions, owing to decreased CO 2 solubility; and reduced CO 2 uptake in the mid latitudes, owing to decreased CO 2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra tropics, to large freshwater fluxes in the extra tropical North Atlantic Ocean, and to small changes in the CO 2 solubility in the equatorial regions. In key anthropogenic CO 2 uptake regions, the climate-induced component offsets the CO 2 - induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra tropics and 25% in the southern extra tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO 2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

  17. Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: a multi model linear feedback analysis

    International Nuclear Information System (INIS)

    Roy, Tilla; Bopp, Laurent; Gehlen, Marion; Cadule, Patricia; Schneider, Birgit; Frolicher, Thomas L.; Segschneider, Joachim; Tjiputra, Jerry; Heinze, Christoph; Joos, Fortunat

    2011-01-01

    The increase in atmospheric CO 2 over this century depends on the evolution of the oceanic air-sea CO 2 uptake, which will be driven by the combined response to rising atmospheric CO 2 itself and climate change. Here, the future oceanic CO 2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO 2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO 2 uptake into a CO 2 -induced component, due to rising atmospheric CO 2 concentrations, and a climate-induced component, due to global warming. The models capture the observation based magnitude and distribution of anthropogenic CO 2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO 2 uptake in the sub polar Southern Ocean and the equatorial regions, owing to decreased CO 2 solubility; and reduced CO 2 uptake in the mid-latitudes, owing to decreased CO 2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extra-tropics, to large freshwater fluxes in the extra-tropical North Atlantic Ocean, and to small changes in the CO 2 solubility in the equatorial regions. In key anthropogenic CO 2 uptake regions, the climate-induced component offsets the CO 2 - induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extra-tropics and 25% in the southern extra-tropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO 2 uptake may be difficult without monitoring additional tracers, such as oxygen. (authors)

  18. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-01-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  19. Feedbacks of CO2 dependent dissolved organic carbon production on atmospheric CO2 in an ocean biogeochemical model

    Science.gov (United States)

    Bordelon-Katrynski, L. A.; Schneider, B.

    2012-07-01

    We use an ocean biogeochemical model to test whether a potential CO2 dependence of dissolved organic carbon (DOC) production may have an influence on marine carbon sequestration via particle aggregation and so may represent a potentially larger ocean sink for anthropogenic CO2. The hypothesis is based on mesocosm experiments that have shown enhanced carbon uptake by phytoplankton when more CO2 is available, and where the extra carbon was probably directly routed into DOC instead of the particulate phase. Sensitivity experiments are carried out where phytoplankton exudation of DOC is systematically increased with and without a parallel rise in atmospheric CO2. We find that under a fourfold increase of the DOC formation rate, there is a slight reduction of global particle export, which results in a shallower turnover of nutrients and carbon. As a consequence, a positive feedback loop develops, such that the ocean becomes a weak source of CO2 to the atmosphere. The effect is amplified under high CO2 conditions due to the decreased CO2 buffer capacity of the ocean, however, it is rather low compared to the total anthropogenic perturbation. The positive feedback is in contrast to a very similar study, where a slight stimulation of particle export was found. Therefore, we conclude that the sign of the feedback depends on the actual pathway the extra carbon is taking and on the overall background conditions of marine primary production and ocean circulation.

  20. Quantification of a maximum injection volume of CO2 to avert geomechanical perturbations using a compositional fluid flow reservoir simulator

    Science.gov (United States)

    Jung, Hojung; Singh, Gurpreet; Espinoza, D. Nicolas; Wheeler, Mary F.

    2018-02-01

    Subsurface CO2 injection and storage alters formation pressure. Changes of pore pressure may result in fault reactivation and hydraulic fracturing if the pressure exceeds the corresponding thresholds. Most simulation models predict such thresholds utilizing relatively homogeneous reservoir rock models and do not account for CO2 dissolution in the brine phase to calculate pore pressure evolution. This study presents an estimation of reservoir capacity in terms of allowable injection volume and rate utilizing the Frio CO2 injection site in the coast of the Gulf of Mexico as a case study. The work includes laboratory core testing, well-logging data analyses, and reservoir numerical simulation. We built a fine-scale reservoir model of the Frio pilot test in our in-house reservoir simulator IPARS (Integrated Parallel Accurate Reservoir Simulator). We first performed history matching of the pressure transient data of the Frio pilot test, and then used this history-matched reservoir model to investigate the effect of the CO2 dissolution into brine and predict the implications of larger CO2 injection volumes. Our simulation results -including CO2 dissolution- exhibited 33% lower pressure build-up relative to the simulation excluding dissolution. Capillary heterogeneity helps spread the CO2 plume and facilitate early breakthrough. Formation expansivity helps alleviate pore pressure build-up. Simulation results suggest that the injection schedule adopted during the actual pilot test very likely did not affect the mechanical integrity of the storage complex. Fault reactivation requires injection volumes of at least about sixty times larger than the actual injected volume at the same injection rate. Hydraulic fracturing necessitates much larger injection rates than the ones used in the Frio pilot test. Tested rock samples exhibit ductile deformation at in-situ effective stresses. Hence, we do not expect an increase of fault permeability in the Frio sand even in the presence of

  1. Using atmospheric CO2 data to assess a simplified carbon-climate simulation for the 20th century

    International Nuclear Information System (INIS)

    Law, Rachel M.; Kowalczyk, Eva A.; Wangs, Ying-Ping

    2006-01-01

    The CSIRO biosphere model has been coupled to an atmosphere model and a simulation has been performed for the 20th century. Both biosphere and atmosphere are forced with global CO 2 concentration and the atmosphere is also forced with prescribed sea surface temperatures. The simulation follows the C4MIP Phase 1 protocol. We assess the model simulation using atmospheric CO 2 data. Mauna Loa growth rate is well simulated from 1980 but overestimated before that time. The interannual variations in growth rate are reasonably reproduced. Seasonal cycles are underestimated in northern mid-latitudes and are out of phase in the southern hemisphere. The north-south gradient of annual mean CO 2 is substantially overestimated due to a northern hemisphere net biosphere source and a southern tropical sink. Diurnal cycles at three northern hemisphere locations are larger than observed in many months, most likely due to larger respiration than observed

  2. CFD Convective Flow Simulation of the Varying Properties of CO2-H2O Mixtures in Geothermal Systems

    Directory of Open Access Journals (Sweden)

    S. Yousefi

    2015-01-01

    Full Text Available Numerical simulation of a geothermal reservoir, modelled as a bottom-heated square box, filled with water-CO2 mixture is presented in this work. Furthermore, results for two limiting cases of a reservoir filled with either pure water or CO2 are presented. Effects of different parameters including CO2 concentration as well as reservoir pressure and temperature on the overall performance of the system are investigated. It has been noted that, with a fixed reservoir pressure and temperature, any increase in CO2 concentration leads to better performance, that is, stronger convection and higher heat transfer rates. With a fixed CO2 concentration, however, the reservoir pressure and temperature can significantly affect the overall heat transfer and flow rate from the reservoir. Details of such variations are documented and discussed in the present paper.

  3. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    Science.gov (United States)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent

  4. The Influence of Internal Model Variability in GEOS-5 on Interhemispheric CO2 Exchange

    Science.gov (United States)

    Allen, Melissa; Erickson, David; Kendall, Wesley; Fu, Joshua; Ott, Leslie; Pawson, Steven

    2012-01-01

    An ensemble of eight atmospheric CO2 simulations was completed employing the National Aeronautics and Space Administration (NASA) Goddard Earth Observation System, Version 5 (GEOS-5) for the years 2000-2001, each with initial meteorological conditions corresponding to different days in January 2000 to examine internal model variability. Globally, the model runs show similar concentrations of CO2 for the two years, but in regions of high CO2 concentrations due to fossil fuel emissions, large differences among different model simulations appear. The phasing and amplitude of the CO2 cycle at Northern Hemisphere locations in all of the ensemble members is similar to that of surface observations. In several southern hemisphere locations, however, some of the GEOS-5 model CO2 cycles are out of phase by as much as four months, and large variations occur between the ensemble members. This result indicates that there is large sensitivity to transport in these regions. The differences vary by latitude-the most extreme differences in the Tropics and the least at the South Pole. Examples of these differences among the ensemble members with regard to CO2 uptake and respiration of the terrestrial biosphere and CO2 emissions due to fossil fuel emissions are shown at Cape Grim, Tasmania. Integration-based flow analysis of the atmospheric circulation in the model runs shows widely varying paths of flow into the Tasmania region among the models including sources from North America, South America, South Africa, South Asia and Indonesia. These results suggest that interhemispheric transport can be strongly influenced by internal model variability.

  5. An Analysis Based on SD Model for Energy-Related CO2 Mitigation in the Chinese Household Sector

    Directory of Open Access Journals (Sweden)

    Xingpeng Chen

    2016-12-01

    Full Text Available Reducing carbon dioxide (CO2 emissions has become a global consensus in response to global warming and climate change, especially to China, the largest CO2 emitter in the world. Most studies have focused on CO2 emissions from the production sector, however, the household sector plays an important role in the total energy-related CO2 emissions. This study formulates an integrated model based on logarithmic mean Divisia index methodology and a system dynamics model to dynamically simulate household energy consumption and CO2 emissions under different conditions. Results show the following: (1 the integrated model performs well in calculating the contribution of influencing factors on household CO2 emissions and analyzing the options for CO2 emission mitigation; (2 the increase in income is the dominant driving force of household CO2 emissions, and as a result of the improved standard of living in China a sustained increase in household CO2 emissions can be expected; (3 with decreasing energy intensity, CO2 emissions will decrease to 404.26 Mt-CO2 in 2020, which is 9.84% lower than the emissions in 2014; (4 the reduction potential by developing non-fossil energy sources is limited, and raising the rate of urbanization cannot reduce the household CO2 emission under the comprehensive influence of other factors.

  6. [Responses of Pinus tabulaeformis forest ecosystem in North China to climate change and elevated CO2: a simulation based on BIOME-BGC model and tree-ring data].

    Science.gov (United States)

    He, Jun-Jie; Peng, Xing-Yuan; Chen, Zhen-Ju; Cui, Ming-Xing; Zhang, Xian-Liang; Zhou, Chang-Hong

    2012-07-01

    Based on BIOME-BGC model and tree-ring data, a modeling study was conducted to estimate the dynamic changes of the net primary productivity (NPP) of Pinus tabulaeformis forest ecosystem in North China in 1952-2008, and explore the responses of the radial growth and NPP to regional climate warming as well as the dynamics of the NPP in the future climate change scenarios. The simulation results indicated the annual NPP of the P. tabulaeformis ecosystem in 1952-2008 fluctuated from 244.12 to 645.31 g C x m(-2) x a(-1), with a mean value of 418.6 g C x m(-2) x a(-1) The mean air temperature in May-June and the precipitation from previous August to current July were the main factors limiting the radial growth of P. tabulaeformis and the NPP of P. tabulaeformis ecosystem. In the study period, both the radial growth and the NPP presented a decreasing trend due to the regional warming and drying climate condition. In the future climate scenarios, the NPP would have positive responses to the increase of air temperature, precipitation, and their combination. The elevated CO2 would benefit the increase of the NPP, and the increment would be about 16.1% due to the CO2 fertilization. At both ecosystem and regional scales, the tree-ring data would be an ideal proxy to predict the ecosystem dynamic change, and could be used to validate and calibrate the process-based ecosystem models including BIOME-BGC.

  7. Simulation of commercial scale CO2 injection into a fracture reservoir

    Science.gov (United States)

    Li, Y.; Li, S.; Zhang, Y.

    2011-12-01

    Geologic Carbon Sequestration is a proposed means to reduce atmospheric concentration of carbon dioxide (CO2). At Teapot Dome, Wyoming, CO2 will be injected into the Tensleep Formation, a depleted oil reservoir characterized with significant heterogeneity including facies, faults, and fractures. We've collected geological and engineering characterization data of the entire Teapot Dome field, including core data, well logs, seismic data, and production records. All data were screened for accuracy, before subsets of the data are used to build a geologic reservoir model. A formation structural model is created first by interpreting faults and stratigraphy from 3D seismic data. Formation MicroImager logs are analyzed for fracture characteristics to generate in-situ fracture intensity at wells, which is subsequently interpolated throughout the model with kriging. Based on the intensity and a set of geometric fracture parameters (constrained by outcrop and core measurements), a 3D stochastic Discrete Fracture Network (DFN) is created. One realization of the DFN is upscaled to a dual-porosity simulation model using a variant of the Oda's method. This method upscales the fracture network to an effective grid-block fracture permeability. To account for fluid transfer from matrix to fracture, a sigma factor is computed using average fracture spacings within the grid block. Matrix porosity is populated in the model by kriging interpolation of well-log-derived values. With the dual-porosity model, CO2 is injected near the crest of the dome (the proposed location) at a rate of 2.6 Mt/year for 50 years, with an injection bottomhole pressure set at 160% hydrostatic pressure. Boundary of the model is open except along one bounding fault assumed sealed. Results of the simulation suggest that provided that fluid pressure buildup is not an issue (simulated pressure buildup near the fault is minor), the Tensleep Formation at Teapot Dome can sustain commercial-scale injection over time

  8. CO2 release experiment in the shallow subsurface at the Brackenridge Field Laboratory and numerical modeling

    Science.gov (United States)

    Yang, C.; Romanak, K.; Hovorka, S.

    2009-12-01

    Soil gas monitoring is one cost-effective approach to detect CO2 leak at geological sequestration sites. Therefore understanding CO2 gas transport in soil zones is important for detection of CO2 leaks. A field experiment of a small CO2 release was conducted at the Brackenridge Field Laboratory, the University of Texas at Austin. The field site consists of one injection well, two sensor wells and one gas station well (Figure 1). The injection well was completed with a PVC pipe to a depth of 1.1 m below surface. CO2 sensors were deployed in sensor wells about 42 cm from the injection well at depths of 1.1 m having no subsurface PVC pipes but only a PVC protector cap at the surface. The gas monitoring station about 72 cm away from the injection well contains 3 copper tubes each set at different depths in sand pack isolated with bentonite clay. The CO2 release experiment started on March 4, 2009. A total 36.76 liters of CO2 were injected at 1 m depth at a rate of 100 ml/minute for 6 hours. Subsurface CO2 gas concentrations (before, during, and after the injection) were continuously monitored in sensor wells. Real-time CO2 concentrations were monitored at the gas station using an SRI 8610 gas chromatograph (GC) fitted with flame ionization detector (FID) and a thermal conductivity detector (TCD). A numerical model was constructed to simulate CO2 release experiments. The model takes into account CO2 diffusion and dissolution in pore water. Air in the pore space is assumed stagnant. Model domain consists of four soil layers and one atmospheric layer. The groundwater table is about 2.4 meters below ground surface. The model was calibrated with respect to diffusion coefficient (transport parameter) and the injection rate (mass parameter). Model results fit well with CO2 measurements at the sensor wells and the gas station. However, the calibrated injection rate underestimates measured injection rate.

  9. Importance of crop varieties and management practices: evaluation of a process-based model for simulating CO2 and H2O fluxes at five European maize (Zea mays L.) sites

    NARCIS (Netherlands)

    Li, L.; Vuichard, N.; Viovy, N.; Ciais, P.; Wang, T.; Ceschia, E.; Jans, W.W.P.; Wattenbach, M.; Beziat, P.; Gruenwald, T.; Lehuger, S.; Bernhofer, C.

    2011-01-01

    This paper is a modelling study of crop management impacts on carbon and water fluxes at a range of European sites. The model is a crop growth model (STICS) coupled with a process-based land surface model (ORCHIDEE). The data are online eddy-covariance observations of CO2 and H2O fluxes at five

  10. A bio-metal-organic framework for highly selective CO(2) capture: A molecular simulation study.

    Science.gov (United States)

    Chen, Yifei; Jiang, Jianwen

    2010-08-23

    A recently synthesized bio-metal-organic framework (bio-MOF-11) is investigated for CO(2) capture by molecular simulation. The adenine biomolecular linkers in bio-MOF-11 contain Lewis basic amino and pyrimidine groups as the preferential adsorption sites. The simulated and experimental adsorption isotherms of pure CO(2), H(2), and N(2) are in perfect agreement. Bio-MOF-11 exhibits larger adsorption capacities compared to numerous zeolites, activated carbons, and MOFs, which is attributed to the presence of multiple Lewis basic sites and nano-sized channels. The results for the adsorption of CO(2)/H(2) and CO(2)/N(2) mixtures in bio-MOF-11 show that CO(2) is more dominantly adsorbed than H(2) and N(2). With increasing pressure, the selectivity of CO(2)/H(2) initially increases owing to the strong interactions between CO(2) and the framework, and then decreases as a consequence of the entropy effect. However, the selectivity of CO(2)/N(2) monotonically increases with increasing pressure and finally reaches a constant. The selectivities in bio-MOF-11 are higher than in many nanoporous materials. The simulation results also reveal that a small amount of H(2)O has a negligible effect on the separation of CO(2)/H(2) and CO(2)/N(2) mixtures. The simulation study provides quantitative microscopic insight into the adsorption mechanism in bio-MOF-11 and suggests that bio-MOF-11 may be interesting for pre- and post-combustion CO(2) capture.

  11. Characterization and modelling of a naturally fractured reservoir-caprock unit targeted for CO2 storage in arctic Norway

    NARCIS (Netherlands)

    Senger, K.; Mulrooney, M.; Schaaf, N.; Tveranger, J.; Braathen, A.; Ogata, K.; Olaussen, S.

    2017-01-01

    Successfully storing CO2 underground requires a good understanding of the subsurface at the storage site, and its robust representation in geological models. Geological models, and related simulations, provide important quantitative information on critical parameters for the optimal utilisation of

  12. 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

  13. Mathematical model of CO2release during milk fermentation using natural kefir grains.

    Science.gov (United States)

    Goršek, Andreja; Ritonja, Jožef; Pečar, Darja

    2018-03-12

    Milk fermentation takes place in the presence of various micro-organisms, whereby a variety of dairy products is produced. The oldest among them is kefir, which is usually produced by fermentation of milk with kefir grains. Carbon dioxide (CO 2 ), as one of the process products, also contributes to the characteristic flavor of kefir. The amount of CO 2 generated during fermentation depends on bioprocessing conditions and may change, which is not desirable at the industrial level. In this study we developed a simplified mathematical model of CO 2 release in the milk fermentation process. An intuitive approach based on superposition and experimental analysis was used for the modeling. The chemical system studied was considered as a two-input (temperature, rotational frequency of the stirrer) one-output (CO 2 concentration) dynamic system. Based on an analysis of CO 2 release transients in the case of non-simultaneous stepwise changed input quantities, two differential equations which describe the influence of the two input quantities on the output quantity were defined. The simulation results were verified by experiments. The proposed model can be used for a comprehensive analysis of the process studied and for the design and synthesis of advanced control systems, which will assure a controlled CO 2 release at the industrial level. This article is protected by copyright. All rights reserved.

  14. Superior Selective CO2 Adsorption of C3N Pores: GCMC and DFT Simulations.

    Science.gov (United States)

    Li, Xiaofang; Zhu, Lei; Xue, Qingzhong; Chang, Xiao; Ling, Cuicui; Xing, Wei

    2017-09-13

    Development of high-performance sorbents is extremely significant for CO 2 capture due to its increasing atmospheric concentration and impact on environmental degradation. In this work, we develop a new model of C 3 N pores based on GCMC calculations to describe its CO 2 adsorption capacity and selectivity. Remarkably, it exhibits an outstanding CO 2 adsorption capacity and selectivity. For example, at 0.15 bar it shows exceptionally high CO 2 uptakes of 3.99 and 2.07 mmol/g with good CO 2 /CO, CO 2 /H 2 , and CO 2 /CH 4 selectivity at 300 and 350 K, separately. More importantly, this adsorbent also shows better water stability. Specifically, its CO 2 uptakes are 3.80 and 5.91 mmol/g for and 0.15 and 1 bar at 300 K with a higher water content. Furthermore, DFT calculations demonstrate that the strong interactions between C 3 N pores and CO 2 molecules contribute to its impressive CO 2 uptake and selectivity, indicating that C 3 N pores can be an extremely promising candidate for CO 2 capture.

  15. Importance of crop varieties and management practices: evaluation of a process-based model for simulating CO2 and H2O fluxes at five European maize (Zea mays L.) sites

    Science.gov (United States)

    Li, L.; Vuichard, N.; Viovy, N.; Ciais, P.; Ceschia, E.; Jans, W.; Wattenbach, M.; Béziat, P.; Gruenwald, T.; Lehuger, S.; Bernhofer, C.

    2011-03-01

    Crop varieties and management practices such as planting and harvest dates, irrigation, and fertilization have important effects on the water and carbon fluxes over croplands, and lack or inaccuracy of this information may cause large uncertainties in hydraulic and carbon modeling. Yet the magnitude of uncertainties has not been investigated in detail. This paper provides a comprehensive assessment of the performances of a process-based ecosystem model called ORCHIDEE-STICS (a coupled model between generic ecosystem model ORCHIDEE and the crop growth model STICS), against eddy-covariance observations of CO2 and H2O fluxes at five European maize cultivation sites. The results show that ORCHIDEE-STICS has a good potential to simulate energy, water vapor and carbon dioxide fluxes from maize croplands on a daily basis. The model explains 23-75% of the observed daily net ecosystem exchange (NEE) variance at five sites, and 26-79% of the latent heat flux (LE) variance. Similarly, 34-83% of the variance in observed gross primary productivity (GPP) is accounted for by the model. However, only 3-81% of the variance of observed terrestrial ecosystem respiration (TER) is explained. Therefore, simulating TER is shown to be much more difficult than GPP. We conclude that structural deficiencies of the model in the determination of LAI and TER are the main sources of errors in simulating carbon dioxide and water vapor fluxes. A group of sensitivity analyses, by setting different crop variety, nitrogen fertilization, irrigation, and planting date, indicate that any of these factors is able to cause more than 15% change in simulated NEE although the response of these fluxes to management parameters is site-dependent. Varying management practice in the model is shown to affect not only the daily values of NEE and LE, but also the total seasonal cumulative values, and therefore the annual carbon and water budgets. However, LE is found to be less sensitive to management practices than

  16. Observing System Simulations for the NASA ASCENDS Lidar CO2 Mission Concept: Substantiating Science Measurement Requirements

    Science.gov (United States)

    Kawa, S. R.; Baker, D. F.; Schuh, A. E.; Abshire, J. B.; Browell, E. V.; Michalak, A. M.

    2012-12-01

    The NASA ASCENDS mission (Active Sensing of Carbon Emissions, Nights, Days, and Seasons) is envisioned as the next generation of dedicated, space-based CO2 observing systems, currently planned for launch in about the year 2022. Recommended by the US National Academy of Sciences Decadal Survey, active (lidar) sensing of CO2 from space has several potentially significant advantages, in comparison to current and planned passive CO2 instruments, that promise to advance CO2 measurement capability and carbon cycle understanding into the next decade. Assessment and testing of possible lidar instrument technologies indicates that such sensors are more than feasible, however, the measurement precision and accuracy requirements remain at unprecedented levels of stringency. It is, therefore, important to quantitatively and consistently evaluate the measurement capabilities and requirements for the prospective active system in the context of advancing our knowledge of carbon flux distributions and their dependence on underlying physical processes. This amounts to establishing minimum requirements for precision, relative accuracy, spatial/temporal coverage and resolution, vertical information content, interferences, and possibly the tradeoffs among these parameters, while at the same time framing a mission that can be implemented within a constrained budget. Here, we present results of observing system simulation studies, commissioned by the ASCENDS Science Requirements Definition Team, for a range of possible mission implementation options that are intended to substantiate science measurement requirements for a laser-based CO2 space instrument. To this end, we have assembled a relatively complete description of the prospective mission sampling, atmospheric, and surface states that enables us to quantitatively scale measurement errors globally for a variety of nominal CO2 instrument approaches. The resulting error distributions are used in inverse studies to estimate the impact

  17. Methane and CO2Adsorption Capacities of Kerogen in the Eagle Ford Shale from Molecular Simulation.

    Science.gov (United States)

    Psarras, Peter; Holmes, Randall; Vishal, Vikram; Wilcox, Jennifer

    2017-08-15

    Over the past decade, the United States has become a world leader in natural gas production, thanks in part to a large-fold increase in recovery from unconventional resources, i.e., shale rock and tight oil reservoirs. In an attempt to help mitigate climate change, these depleted formations are being considered for their long-term CO 2 storage potential. Because of the variability in mineral and structural composition from one formation to the next (even within the same region), it is imperative to understand the adsorption behavior of CH 4 and CO 2 in the context of specific conditions and pore surface chemistry, i.e., relative total organic content (TOC), clay, and surface functionality. This study examines two Eagle Ford shale samples, both recovered from shale that was extracted at depths of approximately 3800 m and having low clay content (i.e., less than 5%) and similar mineral compositions but distinct TOCs (i.e., 2% and 5%, respectively). Experimentally validated models of kerogen were used to the estimate CH 4 and CO 2 adsorption capacities. The pore size distributions modeled were derived from low-pressure adsorption isotherm data using CO 2 and N 2 as probe gases for micropores and mesopores, respectively. Given the presence of water in these natural systems, the role of surface chemistry on modeled kerogen pore surfaces was investigated. Several functional groups associated with surface-dissociated water were considered. Pressure conditions from 10 to 50 bar were investigated using grand canonical Monte Carlo simulations along with typical outgassing temperatures used in many shale characterization and adsorption studies (i.e., 60 and 250 °C). Both CO 2 and N 2 were used as probe gases to determine the total pore volume available for gas adsorption spanning pore diameters ranging from 0.3 to 30 nm. The impacts of surface chemistry, outgassing temperature, and the inclusion of nanopores with diameters of less than 1.5 nm were determined for applications

  18. Global Monthly CO2 Flux Inversion Based on Results of Terrestrial Ecosystem Modeling

    Science.gov (United States)

    Deng, F.; Chen, J.; Peters, W.; Krol, M.

    2008-12-01

    Most of our understanding of the sources and sinks of atmospheric CO2 has come from inverse studies of atmospheric CO2 concentration measurements. However, the number of currently available observation stations and our ability to simulate the diurnal planetary boundary layer evolution over continental regions essentially limit the number of regions that can be reliably inverted globally, especially over continental areas. In order to overcome these restrictions, a nested inverse modeling system was developed based on the Bayesian principle for estimating carbon fluxes of 30 regions in North America and 20 regions for the rest of the globe. Inverse modeling was conducted in monthly steps using CO2 concentration measurements of 5 years (2000 - 2005) with the following two models: (a) An atmospheric transport model (TM5) is used to generate the transport matrix where the diurnal variation n of atmospheric CO2 concentration is considered to enhance the use of the afternoon-hour average CO2 concentration measurements over the continental sites. (b) A process-based terrestrial ecosystem model (BEPS) is used to produce hourly step carbon fluxes, which could minimize the limitation due to our inability to solve the inverse problem in a high resolution, as the background of our inversion. We will present our recent results achieved through a combination of the bottom-up modeling with BEPS and the top-down modeling based on TM5 driven by offline meteorological fields generated by the European Centre for Medium Range Weather Forecast (ECMFW).

  19. Simplified models of transport and reactions in conditions of CO2 storage in saline aquifers

    Science.gov (United States)

    Suchodolska, Katarzyna; Labus, Krzysztof

    2016-04-01

    Simple hydrogeochemical models may serve as tools of preliminary assessment of CO2 injection and sequestraton impact on the aquifer and cap-rocks. In order to create models of reaction and transport in conditions of CO2 injection and storage, the TOUGHREACT simulator, and the Geochemist's Workbench software were applied. The chemical composition of waters for kinetic transport models based on the water - rock equilibrium calculations. Analyses of reaction and transport of substances during CO2 injection and storage period were carried out in three scenarios: one-dimensional radial model, and two-dimensional model of CO2 injection and sequestration, and one-dimensional model of aquifer - cap-rock interface. Modeling was performed in two stages. The first one simulated the immediate changes in the aquifer and insulating rocks impacted by CO2 injection (100 days in case of reaction model and 30 years in transport and reaction model), the second - enabled assessment of long-term effects of sequestration (20000 years). Reactions' quality and progress were monitored and their effects on formation porosity and sequestration capacity in form of mineral, residual and free phase of CO2 were calculated. Calibration of numerical models (including precipitation of secondary minerals, and correction of kinetics parameters) describing the initial stage of injection, was based on the experimental results. Modeling allowed to evaluate the pore space saturation with gas, changes in the composition and pH of pore waters, relationships between porosity and permeability changes and crystallization or dissolution minerals. We assessed the temporal and spatial extent of crystallization processes, and the amount of carbonates trapping. CO2 in mineral form. The calculated sequestration capacity of analyzed formations reached n·100 kg/m3 for the: dissolved phase - CO(aq), gas phase - CO2(g) and mineral phase, but as much as 101 kg/m3 for the supercritical phase - SCCO2. Processes of gas

  20. LBA-ECO CD-01 Simulated Atmospheric Circulation, CO2 Variation, Tapajos: August 2001

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set consists of a single NetCDF file containing simulated three dimensional winds and CO2 concentrations centered on the Tapajos National Forest...

  1. LBA-ECO CD-01 Simulated Atmospheric Circulation, CO2 Variation, Tapajos: August 2001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of a single NetCDF file containing simulated three dimensional winds and CO2 concentrations centered on the Tapajos National Forest in Brazil...

  2. Modeling CO2 emissions from Arctic lakes: Model development and site-level study

    Science.gov (United States)

    Tan, Zeli; Zhuang, Qianlai; Shurpali, Narasinha J.; Marushchak, Maija E.; Biasi, Christina; Eugster, Werner; Walter Anthony, Katey

    2017-09-01

    Recent studies indicated that Arctic lakes play an important role in receiving, processing, and storing organic carbon exported from terrestrial ecosystems. To quantify the contribution of Arctic lakes to the global carbon cycle, we developed a one-dimensional process-based Arctic Lake Biogeochemistry Model (ALBM) that explicitly simulates the dynamics of organic and inorganic carbon in Arctic lakes. By realistically modeling water mixing, carbon biogeochemistry, and permafrost carbon loading, the model can reproduce the seasonal variability of CO2 fluxes from the study Arctic lakes. The simulated area-weighted CO2 fluxes from yedoma thermokarst lakes, nonyedoma thermokarst lakes, and glacial lakes are 29.5, 13.0, and 21.4 g C m-2 yr-1, respectively, close to the observed values (31.2, 17.2, and 16.5 ± 7.7 g C m-2 yr-1, respectively). The simulations show that the high CO2 fluxes from yedoma thermokarst lakes are stimulated by the biomineralization of mobilized labile organic carbon from thawing yedoma permafrost. The simulations also imply that the relative contribution of glacial lakes to the global carbon cycle could be the largest because of their much larger surface area and high biomineralization and carbon loading. According to the model, sunlight-induced organic carbon degradation is more important for shallow nonyedoma thermokarst lakes but its overall contribution to the global carbon cycle could be limited. Overall, the ALBM can simulate the whole-lake carbon balance of Arctic lakes, a difficult task for field and laboratory experiments and other biogeochemistry models.

  3. 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.

  4. A fully coupled finite element framework for thermal fracturing simulation in subsurface cold CO2 injection

    Directory of Open Access Journals (Sweden)

    Shunde Yin

    2018-03-01

    Simulation of thermal fracturing during cold CO2 injection involves the coupled processes of heat transfer, mass transport, rock deforming as well as fracture propagation. To model such a complex coupled system, a fully coupled finite element framework for thermal fracturing simulation is presented. This framework is based on the theory of non-isothermal multiphase flow in fracturing porous media. It takes advantage of recent advances in stabilized finite element and extended finite element methods. The stabilized finite element method overcomes the numerical instability encountered when the traditional finite element method is used to solve the convection dominated heat transfer equation, while the extended finite element method overcomes the limitation with traditional finite element method that a model has to be remeshed when a fracture is initiated or propagating and fracturing paths have to be aligned with element boundaries.

  5. Using satellite fluorescence data to drive a global carbon cycle model: Impacts on atmospheric CO2.

    Science.gov (United States)

    Collatz, G. J.; Joiner, J.; Kawa, S. R.; Ivanoff, A.; Liu, Y.; Yoshida, Y.; Berry, J. A.; Badgley, G. M.

    2014-12-01

    Atmospheric CO2 variability is markedly influenced by biospheric fluxes (photosynthesis and respiration) from the land surface at seasonal, to annual, to decadal time scales. Process models of photosynthesis and respiration have considerable uncertainty as only the sum of these fluxes can be constrained on the bases of atmospheric CO2 measurements alone. An independent proxy for photosynthesis or gross primary productivity (GPP) has recently become available from measurement of solar induced fluorescence (SIF). We report here on the first (to our knowledge) simulations of global atmospheric CO2 concentration driven by GPP estimated from observations of SIF. A baseline model uses satellite derived FPAR, incident solar radiation, temperature, and moisture stress scalars to estimate net primary productivity (NPP). The fluorescence driven model uses only fluorescence from GOME-2 scaled to the mean annual NPP at every grid cell and assumes a constant NPP/GPP ratio. Respiration was modeled identically in the two simulations. This preserves the spatial distribution of production capacity but allows for independent seasonal cycle and interannual variability from the baseline model. The flux models were run at ½ degree monthly resolution for 2007-2012 and fluxes were reaggregated along with fossil fuel and ocean fluxes to 3-hourly, 1 x 1.25 degree resolution for the atmospheric transport model. Here, we compare the model's skill at predicting CO2 variability at 40 NOAA CO2 flask network sites. The baseline model shows good skill at matching the seasonal cycle at the flask sites but is not as good at producing monthly and interannual anomalies. The fluorescence model shows similar (or even improved) performance even though solar radiation, FPAR, precipitation and temperature effects on GPP are not included in the simulation. The results demonstrate the capability of the fluorescence data to integrate physiological and biophysical controls on GPP into a single measured

  6. A liquid CO2-compatible hydrocarbon surfactant: experiment and modelling

    NARCIS (Netherlands)

    Banerjee, S.; Kleijn, J.M.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2013-01-01

    Surfactants soluble in liquid CO2 are rare and knowledge on interfacial and self-assembly behaviour is fragmented. We found that polyoxyethylene (5) isooctylphenyl ether is interfacially active at the water–liquid CO2 interface. Water–liquid CO2 interfacial tension was measured at various surfactant

  7. A locational gaming model with CO2 emission tax and limits

    International Nuclear Information System (INIS)

    Yu, Z.; Preckel, P.V.; Nderitu, G.; Sparrow, F.T.

    2001-01-01

    This paper presents a locational (spatial) gaming model with CO 2 emission and transmission capacity limits. It is developed for simulating strategic behavior of electricity producers in deregulated electricity markets. The model has multiple players, each maximizing their individual profit with a CO 2 emission tax included to reflect the societal cost of environment damages caused by CO 2 emission from different locations. In the paper, the multiple-producer profits are converted into a set of Lagrangian functions with power production and supply as the primary control variables, resulting in a set of unconstrained, individual profit maximization equations. The Karush-Kuhn-Tucker necessary conditions are then derived and solved simultaneously incorporating Cournot gaming strategy. Case studies show the successful application of the model. (author)

  8. Wave optics simulation of atmospheric turbulence and reflective speckle effects in CO2 lidar.

    Science.gov (United States)

    Nelson, D H; Walters, D L; Mackerrow, E P; Schmitt, M J; Quick, C R; Porch, W M; Petrin, R R

    2000-04-20

    Laser speckle can influence lidar measurements from a diffuse hard target. Atmospheric optical turbulence will also affect the lidar return signal. We present a numerical simulation that models the propagation of a lidar beam and accounts for both reflective speckle and atmospheric turbulence effects. Our simulation is based on implementing a Huygens-Fresnel approximation to laser propagation. A series of phase screens, with the appropriate atmospheric statistical characteristics, are used to simulate the effect of atmospheric turbulence. A single random phase screen is used to simulate scattering of the entire beam from a rough surface. We compare the output of our numerical model with separate CO(2) lidar measurements of atmospheric turbulence and reflective speckle. We also compare the output of our model with separate analytical predictions for atmospheric turbulence and reflective speckle. Good agreement was found between the model and the experimental data. Good agreement was also found with analytical predictions. Finally, we present results of a simulation of the combined effects on a finite-aperture lidar system that are qualitatively consistent with previous experimental observations of increasing rms noise with increasing turbulence level.

  9. Evaluation of Diagnostic CO2 Flux and Transport Modeling in NU-WRF and GEOS-5

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Tao, Z.; Wang, J. S.; Ott, L. E.; Liu, Y.; Andrews, A. E.; Sweeney, C.

    2015-12-01

    We report on recent diagnostic (constrained by observations) model simulations of atmospheric CO2 flux and transport using a newly developed facility in the NASA Unified-Weather Research and Forecast (NU-WRF) model. The results are compared to CO2 data (ground-based, airborne, and GOSAT) and to corresponding simulations from a global model that uses meteorology from the NASA GEOS-5 Modern Era Retrospective analysis for Research and Applications (MERRA). The objective of these intercomparisons is to assess the relative strengths and weaknesses of the respective models in pursuit of an overall carbon process improvement at both regional and global scales. Our guiding hypothesis is that the finer resolution and improved land surface representation in NU-WRF will lead to better comparisons with CO2 data than those using global MERRA, which will, in turn, inform process model development in global prognostic models. Initial intercomparison results, however, have generally been mixed: NU-WRF is better at some sites and times but not uniformly. We are examining the model transport processes in detail to diagnose differences in the CO2 behavior. These comparisons are done in the context of a long history of simulations from the Parameterized Chemistry and Transport Model, based on GEOS-5 meteorology and Carnegie Ames-Stanford Approach-Global Fire Emissions Database (CASA-GFED) fluxes, that capture much of the CO2 variation from synoptic to seasonal to global scales. We have run the NU-WRF model using unconstrained, internally generated meteorology within the North American domain, and with meteorological 'nudging' from Global Forecast System and North American Regional Reanalysis (NARR) in an effort to optimize the CO2 simulations. Output results constrained by NARR show the best comparisons to data. Discrepancies, of course, may arise either from flux or transport errors and compensating errors are possible. Resolving their interplay is also important to using the data in

  10. Optimisation modelling predicts leaf trait variation and response to elevated CO2

    Science.gov (United States)

    Pepper, D. A.; McMurtrie, R. E.; Norby, R. J.

    2009-12-01

    The capacities of a plant to obtain the resources it requires and the efficiencies of use of those resources are important determinants of the rate of plant carbon production. Such capacities and efficiencies rely strongly on plant traits, across all relevant scales of plant function (molecular to whole plant). Within inherent (genetic) constraints to the expression of plant traits by any one plant species, a plant would do well to adjust its traits in such a way as to maximise production. We test this hypothesis using a simple plant carbon-nitrogen model applied to a free-air CO2 enrichment (FACE) experiment on sweetgum forest at Oak Ridge, Tennessee, USA. The sweetgum (Liquidambar styraciflua) stand, exposed to ambient atmospheric CO2 or air enriched with CO2 to 550 ppm since 1998, has shown a positive response of net primary productivity (NPP) to elevated CO2 compared to the ambient control. Experiments like this one have been conducted to gauge the response of the biosphere to the significant increase in atmospheric CO2 concentration. In this study we use optimisation modelling to maximise photosynthetic nitrogen use efficiency and output corresponding optimal leaf traits, including (on a per unit leaf area basis): leaf nitrogen content (N), leaf mass (LMA), maximum rate of CO2 assimilation (Amax), average rate of CO2 assimilation (A), and leaf respiration (R). The optimal leaf traits change under a diminishing light level with canopy depth. Integration over canopy depth provides an estimate of canopy total carbon (carbon allocated to leaves), carbon production, canopy carbon export (carbon allocation to wood, fine roots and reproductive structures), and plant N demand to support a canopy comprised of optimal leaves. Thus, simulated plant N demand depends on leaf traits and light level. When simulated plant N demand exceeds N availability, leaf area adjustment occurs, which has impacts on canopy total carbon, carbon production, and canopy carbon export (plant

  11. Modelling CO2 emissions from water surface of a boreal hydroelectric reservoir.

    Science.gov (United States)

    Wang, Weifeng; Roulet, Nigel T; Kim, Youngil; Strachan, Ian B; Del Giorgio, Paul; Prairie, Yves T; Tremblay, Alain

    2018-01-15

    To quantify CO 2 emissions from water surface of a reservoir that was shaped by flooding the boreal landscape, we developed a daily time-step reservoir biogeochemistry model. We calibrated the model using the measured concentrations of dissolved organic and inorganic carbon (C) in a young boreal hydroelectric reservoir, Eastmain-1 (EM-1), in northern Quebec, Canada. We validated the model against observed CO 2 fluxes from an eddy covariance tower in the middle of EM-1. The model predicted the variability of CO 2 emissions reasonably well compared to the observations (root mean square error: 0.4-1.3gCm -2 day -1 , revised Willmott index: 0.16-0.55). In particular, we demonstrated that the annual reservoir surface effluxes were initially high, steeply declined in the first three years, and then steadily decreased to ~115gCm -2 yr -1 with increasing reservoir age over the estimated "engineering" reservoir lifetime (i.e., 100years). Sensitivity analyses revealed that increasing air temperature stimulated CO 2 emissions by enhancing CO 2 production in the water column and sediment, and extending the duration of open water period over which emissions occur. Increasing the amount of terrestrial organic C flooded can enhance benthic CO 2 fluxes and CO 2 emissions from the reservoir water surface, but the effects were not significant over the simulation period. The model is useful for the understanding of the mechanism of C dynamics in reservoirs and could be used to assist the hydro-power industry and others interested in the role of boreal hydroelectric reservoirs as sources of greenhouse gas emissions. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. LABORATORY EXPERIMENTS TO SIMULATE CO2 OCEAN DISPOSAL

    Energy Technology Data Exchange (ETDEWEB)

    Stephen M. Masutani

    1999-12-31

    This Final Technical Report summarizes the technical accomplishments of an investigation entitled ''Laboratory Experiments to Simulate CO{sub 2} Ocean Disposal'', funded by the U.S. Department of Energy's University Coal Research Program. This investigation responds to the possibility that restrictions on greenhouse gas emissions may be imposed in the future to comply with the Framework Convention on Climate Change. The primary objective of the investigation was to obtain experimental data that can be applied to assess the technical feasibility and environmental impacts of oceanic containment strategies to limit release of carbon dioxide (CO{sub 2}) from coal and other fossil fuel combustion systems into the atmosphere. A number of critical technical uncertainties of ocean disposal of CO{sub 2} were addressed by performing laboratory experiments on liquid CO{sub 2} jet break-up into a dispersed droplet phase, and hydrate formation, under deep ocean conditions. Major accomplishments of this study included: (1) five jet instability regimes were identified that occur in sequence as liquid CO{sub 2} jet disintegration progresses from laminar instability to turbulent atomization; (2) linear regression to the data yielded relationships for the boundaries between the five instability regimes in dimensionless Ohnesorge Number, Oh, and jet Reynolds Number, Re, space; (3) droplet size spectra was measured over the full range of instabilities; (4) characteristic droplet diameters decrease steadily with increasing jet velocity (and increasing Weber Number), attaining an asymptotic value in instability regime 5 (full atomization); and (5) pre-breakup hydrate formation appears to affect the size distribution of the droplet phase primary by changing the effective geometry of the jet.

  13. Correlation of Amine Swingbed On-Orbit CO2 Performance with a Hardware Independent Predictive Model

    Science.gov (United States)

    Papale, William; Sweterlitsch, Jeffery

    2015-01-01

    The Amine Swingbed Payload is an experimental system deployed on the International Space Station (ISS) that includes a two-bed, vacuum regenerated, amine-based carbon dioxide (CO2) removal subsystem as the principal item under investigation. The aminebased subsystem, also described previously in various publications as CAMRAS 3, was originally designed, fabricated and tested by Hamilton Sundstrand Space Systems International, Inc. (HSSSI) and delivered to NASA in November 2008. The CAMRAS 3 unit was subsequently designed into a flight payload experiment in 2010 and 2011, with flight test integration activities accomplished on-orbit between January 2012 and March 2013. Payload activation was accomplished in May 2013 followed by a 1000 hour experimental period. The experimental nature of the Payload and the interaction with the dynamic ISS environment present unique scientific and engineering challenges, in particular to the verification and validation of the expected Payload CO2 removal performance. A modeling and simulation approach that incorporates principles of chemical reaction engineering has been developed for the amine-based system to predict the dynamic cabin CO2 partial pressure with given inputs of sorbent bed size, process air flow, operating temperature, half-cycle time, CO2 generation rate, cabin volume and the magnitude of vacuum available. Simulation runs using the model to predict ambient CO2 concentrations show good correlation to on-orbit performance measurements and ISS dynamic concentrations for the assumed operating conditions. The dynamic predictive modelling could benefit operational planning to help ensure ISS CO2 concentrations are maintained below prescribed limits and for the Orion vehicle to simulate various operating conditions, scenarios and transients.

  14. PmaCO2 Project: Porosity and CO2 Trapping Mechanisms The Utrillas Formation in SD-1 borehole (Tejada - Burgos): Porosity and Porous Media Modelling

    International Nuclear Information System (INIS)

    Campos, R.; Barrios, I.; Gonzalez, A. M.

    2013-02-01

    The aim of PmaCO 2 project, supported by the Secretary of State and Research MINECO (CGL2011-24768) is to increase the knowledge of the microstructure of porous storage formations and thus contribute to the viability of CO 2 sequestration in geological formations. The microporous structure plays an important role not only in the prevalence of a particular trapping mechanism, but also on the amount of CO 2 immobilized. Utrillas facies are investigated in this project as representatives of a deep saline aquifer storage. This publication is a summary of the work done in the first year of the project. We present a study on microstructure of sandstones Utrillas, sampled in borehole, by applying the mercury intrusion porosimetry technique for the experimental determination of porosity and associated parameters. The porous medium was modeled with the PoreCor simulation code based in intrusion-extrusion curves. (Author) 78 refs.

  15. A reaction-diffusion model of CO2 influx into an oocyte

    Science.gov (United States)

    Somersalo, Erkki; Occhipinti, Rossana; Boron, Walter F.; Calvetti, Daniela

    2012-01-01

    We have developed and implemented a novel mathematical model for simulating transients in surface pH (pHS) and intracellular pH (pHi) caused by the influx of carbon dioxide (CO2) into a Xenopus oocyte. These transients are important tools for studying gas channels. We assume that the oocyte is a sphere surrounded by a thin layer of unstirred fluid, the extracellular unconvected fluid (EUF), which is in turn surrounded by the well-stirred bulk extracellular fluid (BECF) that represents an infinite reservoir for all solutes. Here, we assume that the oocyte plasma membrane is permeable only to CO2. In both the EUF and intracellular space, solute concentrations can change because of diffusion and reactions. The reactions are the slow equilibration of the CO2 hydration-dehydration reactions and competing equilibria among carbonic acid (H2CO3)/bicarbonate ( HCO3-) and a multitude of non-CO2/HCO3- buffers. Mathematically, the model is described by a coupled system of reaction-diffusion equations that—assuming spherical radial symmetry—we solved using the method of lines with appropriate stiff solvers. In agreement with experimental data (Musa-Aziz et al, PNAS 2009, 106:5406–5411), the model predicts that exposing the cell to extracellular 1.5% CO2/10 mM HCO3- (pH 7.50) causes pHi to fall and pHS to rise rapidly to a peak and then decay. Moreover, the model provides insights into the competition between diffusion and reaction processes when we change the width of the EUF, membrane permeability to CO2, native extra-and intracellular carbonic anhydrase-like activities, the non-CO2/HCO3- (intrinsic) intracellular buffering power, or mobility of intrinsic intracellular buffers. PMID:22728674

  16. Modelling the aqueous and nonaqueous interfaces for CO2 electro-reduction over Sn catalysts

    Science.gov (United States)

    Sheng, Tian; Sun, Shi-Gang

    2018-01-01

    In CO2 electroreduction, Sn catalysts with a high overpotential for hydrogen evolution reaction and a high selectivity towards formic acid formation are very attractive. Many efforts have been made for improving the catalytic performance and for understanding the mechanisms. In electrochemistry, the role of solvents for surface reactions was deserved to be investigated, in particular for some nonaqueous solvents. Here, we have modeled the aqueous (water) and nonaqueous (acetonitrile and dichloromethane) for investigation of CO2 electroreduction on Sn surface, by constrained ab initio molecular dynamics simulations and thermodynamic integrations, including a number of explicit solvent molecules in computational models. It was found that CO2 reduction is initiated from formate formation and solvents, in particular, water can effectively facilitate the reaction.

  17. Coupled Model for CO2 Leaks from Geological Storage: Geomechanics, Fluid Flow and Phase Transitions

    Science.gov (United States)

    Gor, G.; Prevost, J.

    2013-12-01

    Deep saline aquifers are considered as a promising option for long-term storage of carbon dioxide. However, risk of CO2 leakage from the aquifers through faults, natural or induced fractures or abandoned wells cannot be disregarded. Therefore, modeling of various leakage scenarios is crucial when selecting a site for CO2 sequestration and choosing proper operational conditions. Carbon dioxide is injected into wells at supercritical conditions (t > 31.04 C, P > 73.82 bar), and these conditions are maintained in the deep aquifers (at 1-2 km depth) due to hydrostatic pressure and geothermal gradient. However, if CO2 and brine start to migrate from the aquifer upward, both pressure and temperature will decrease, and at the depth of 500-750 m, the conditions for CO2 will become subcritical. At subcritical conditions, CO2 starts boiling and the character of the flow changes dramatically due to appearance of the third (vapor) phase and latent heat effects. When modeling CO2 leaks, one needs to couple the multiphase flow in porous media with geomechanics. These capabilities are provided by Dynaflow, a finite element analysis program [1]; Dynaflow has already showed to be efficient for modeling caprock failure causing CO2 leaks [2, 3]. Currently we have extended the capabilities of Dynaflow with the phase transition module, based on two-phase and three-phase isenthalpic flash calculations [4]. We have also developed and implemented an efficient method for solving heat and mass transport with the phase transition using our flash module. Therefore, we have developed a robust tool for modeling CO2 leaks. In the talk we will give a brief overview of our method and illustrate it with the results of simulations for characteristic test cases. References: [1] J.H. Prevost, DYNAFLOW: A Nonlinear Transient Finite Element Analysis Program. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ. http://www.princeton.edu/~dynaflow/ (last update 2013

  18. Carbon dioxide sequestration: Modeling the diffusive and convective transport under a CO2 cap

    KAUST Repository

    Allen, Rebecca

    2012-01-01

    A rise in carbon dioxide levels from industrial emissions is contributing to the greenhouse effect and global warming. CO2 sequestration in saline aquifers is a strategy to reduce atmospheric CO2 levels. Scientists and researchers rely on numerical simulators to predict CO2 storage by modeling the fluid transport behaviour. Studies have shown that after CO2 is injected into a saline aquifer, undissolved CO2 rises due to buoyant forces and will spread laterally away from the injection site under an area of low permeability. CO2 from this ‘capped\\' region diffuses into the fluid underlying it, and the resulting CO2-fluid mixture increases in density. This increase in density leads to gravity-driven convection. Accordingly, diffusive-convective transport is important to model since it predicts an enhanced storage capacity of the saline aquifer. This work incorporates the diffusive and convective transport processes into the transport modeling equation, and uses a self-generated code. Discretization of the domain is done with a cell-centered finite difference method. Cases are set up using similar parameters from published literature in order to compare results. Enhanced storage capacity is predicted in this work, similar to work done by others. A difference in the onset of convective transport between this work and published results is noticed and discussed in this paper. A sensitivity analysis is performed on the density model used in this work, and on the diffusivity value assumed. The analysis shows that the density model and diffusivity value is a key component on simulation results. Also, perturbations are added to porosity and permeability in order to see the effect of perturbations on the onset of convection, and results agree with similar findings by others. This work provides a basis for studying other cases, such as the impact of heterogeneity on the diffusion-convective transport. An extension of this work may involve the use of an equation of state to

  19. Simulating low frequency changes in atmospheric CO2 during the last 740 000 years

    Directory of Open Access Journals (Sweden)

    P. Köhler

    2006-01-01

    Full Text Available Atmospheric CO2 measured in Antarctic ice cores shows a natural variability of 80 to 100 ppmv during the last four glacial cycles and variations of approximately 60 ppmv in the two cycles between 410 and 650 kyr BP. We here use various paleo-climatic records from the EPICA Dome C Antarctic ice core and from oceanic sediment cores covering the last 740 kyr to force the ocean/atmosphere/biosphere box model of the global carbon cycle BICYCLE in a forward mode over this time in order to interpret the natural variability of CO2. Our approach is based on the previous interpretation of carbon cycle variations during Termination I (Köhler et al., 2005a. In the absense of a process-based sediment module one main simplification of BICYCLE is that carbonate compensation is approximated by the temporally delayed restoration of deep ocean [CO32−]. Our results match the low frequency changes in CO2 measured in the Vostok and the EPICA Dome C ice core for the last 650 kyr BP (r2≈0.75. During these transient simulations the carbon cycle reaches never a steady state due to the ongoing variability of the overall carbon budget caused by the time delayed response of the carbonate compensation to other processes. The average contributions of different processes to the rise in CO2 during Terminations I to V and during earlier terminations are: the rise in Southern Ocean vertical mixing: 36/22 ppmv, the rise in ocean temperature: 26/11 ppmv, iron limitation of the marine biota in the Southern Ocean: 20/14 ppmv, carbonate compensation: 15/7 ppmv, the rise in North Atlantic deep water formation: 13/0 ppmv, the rise in gas exchange due to a decreasing sea ice cover: −8/−7 ppmv, sea level rise: −12/−4 ppmv, and rising terrestrial carbon storage: −13/−6 ppmv. According to our model the smaller interglacial CO2 values in the pre-Vostok period prior to Termination V are mainly caused by smaller interglacial Southern Ocean SST and an Atlantic THC which stayed

  20. Hybrid modeling of CO2 sequestration processes using the lattice-Boltzmann method and PFLOTRAN

    Science.gov (United States)

    Porter, M. L.; Coon, E. T.; Kang, Q.; Lichtner, P. C.; Carey, J. W.

    2011-12-01

    Successful CO2 injection and sequestration requires fundamental understanding of many complex processes encountered in multiphase flow and reactive transport through porous media. Although these processes are inherently governed by microscopic interfacial phenomena, they must be described at much larger scales for many practical engineering applications. In this work we present a parallel hybrid modeling scheme that couples a lattice-Boltzmann (LB) simulator for porescale multiphase flow to PFLOTRAN for continuum (Darcy) scale multiphase flow and both continuum and porescale reactive transport. We discuss details regarding the LB method, PFLOTRAN, and the coupling of the two simulators. In addition, we present a number of simulations that validate and highlight both the porescale and hybrid modeling capabilities for applications involving CO2 sequestration.

  1. System-level modeling for geological storage of CO2

    OpenAIRE

    Zhang, Yingqi; Oldenburg, Curtis M.; Finsterle, Stefan; Bodvarsson, Gudmundur S.

    2006-01-01

    One way to reduce the effects of anthropogenic greenhouse gases on climate is to inject carbon dioxide (CO2) from industrial sources into deep geological formations such as brine formations or depleted oil or gas reservoirs. Research has and is being conducted to improve understanding of factors affecting particular aspects of geological CO2 storage, such as performance, capacity, and health, safety and environmental (HSE) issues, as well as to lower the cost of CO2 capture and related p...

  2. Towards the generic conceptual and numerical framework for the simulation of CO 2 sequestration in different types of georeservoirs

    DEFF Research Database (Denmark)

    Görke, Uwe Jens; Taron, Joshua; Singh, Ashok

    2011-01-01

    mathematical models are of similar structure. Thus, the paper is mainly focused on a generic theoretical framework for the coupled processes under consideration. Within this context, CO 2 sequestration in georeservoirs of different type can be simulated (e.g., saline aquifers, (nearly) depleted hydrocarbon...

  3. Effects of temperature and CO2 on the frictional behavior of simulated anhydrite fault rock

    Science.gov (United States)

    Pluymakers, Anne M. H.; Samuelson, Jon E.; Niemeijer, André R.; Spiers, Christopher J.

    2014-12-01

    The frictional behavior of anhydrite-bearing faults is of interest to (a) the safety and effectiveness of CO2 storage in anhydrite-capped reservoirs, (b) seismicity induced by hydrocarbon production, and (c) natural seismicity nucleated in evaporite formations. We performed direct shear experiments on simulated anhydrite fault gouges, at a range of temperatures (80-150°C) and sliding velocities (0.2-10 µm s-1), under a fixed effective normal stress of 25 MPa. Four types of experiments were conducted (1) dry experiments, (2) experiments pressurized with water, (3) dry experiments pressurized with CO2, and (4) wet experiments pressurized with CO2. Fluid pressures of 15 MPa were used when applied. Over the temperature range investigated water-saturated samples were found to be up to 15% frictionally weaker than dry equivalents. Wet samples containing CO2 were also up to 15% weaker than CO2-free equivalents. Dry sample strength without CO2 was independent of temperature, whereas wet samples without CO2 strengthened 10% from 80 to 150°C. Samples containing CO2 weakened by 4% (dry) and 10% (wet) from 80 to 150°C. Under the P-T conditions investigated, only dry anhydrite fault gouge showed velocity-weakening behavior above 120°C, required for faults to potentially generate earthquakes. Assuming natural fault gouges are wet in situ, seismicity is unlikely to nucleate in anhydrite-rich faults, though the presence of dolomite or (reaction-produced) calcite may change seismic potential. CO2 penetration into wet anhydrite-rich faults may trigger slip on critically stressed faults due to the observed short-term CO2 weakening effects (excluding possible formation of secondary minerals), but is not expected to influence slip stability.

  4. Probabilistic modeling and global sensitivity analysis for CO 2 storage in geological formations: a spectral approach

    KAUST Repository

    Saad, Bilal Mohammed

    2017-09-18

    This work focuses on the simulation of CO2 storage in deep underground formations under uncertainty and seeks to understand the impact of uncertainties in reservoir properties on CO2 leakage. To simulate the process, a non-isothermal two-phase two-component flow system with equilibrium phase exchange is used. Since model evaluations are computationally intensive, instead of traditional Monte Carlo methods, we rely on polynomial chaos (PC) expansions for representation of the stochastic model response. A non-intrusive approach is used to determine the PC coefficients. We establish the accuracy of the PC representations within a reasonable error threshold through systematic convergence studies. In addition to characterizing the distributions of model observables, we compute probabilities of excess CO2 leakage. Moreover, we consider the injection rate as a design parameter and compute an optimum injection rate that ensures that the risk of excess pressure buildup at the leaky well remains below acceptable levels. We also provide a comprehensive analysis of sensitivities of CO2 leakage, where we compute the contributions of the random parameters, and their interactions, to the variance by computing first, second, and total order Sobol’ indices.

  5. Characterisation, quantification and modelling of CO2 transport and interactions in a carbonate vadose zone: application to a CO2 diffusive leakage in a geological sequestration context

    International Nuclear Information System (INIS)

    Cohen, Gregory

    2013-01-01

    Global warming is related to atmospheric greenhouse gas concentration increase and especially anthropogenic CO 2 emissions. Geologic sequestration has the potential capacity and the longevity to significantly diminish anthropogenic CO 2 emissions. This sequestration in deep geological formation induces leakage risks from the geological reservoir. Several leakage scenarios have been imagined. Since it could continue for a long period, inducing environmental issues and risks for human, the scenario of a diffusive leakage is the most worrying. Thus, monitoring tools and protocols are needed to set up a near-surface monitoring plan. The present thesis deals with this problematic. The aims are the characterisation, the quantification and the modelling of transport and interactions of CO 2 in a carbonate unsaturated zone. This was achieved following an experimental approach on a natural pilot site in Saint-Emilion (Gironde, France), where diffusive gas leakage experiments were set up in a carbonate unsaturated zone. Different aspects were investigated during the study: natural pilot site description and instrumentation; the physical and chemical characterisation of carbonate reservoir heterogeneity; the natural functioning of the carbonate unsaturated zone and especially the set-up of a CO 2 concentrations baseline; the characterisation of gas plume extension following induced diffusive leakage in the carbonate unsaturated zone and the study of gas-water-rock interactions during a CO 2 diffusive leakage in a carbonate unsaturated zone through numerical simulations. The results show the importance of the carbonate reservoir heterogeneity characterisation as well as the sampling and analysing methods for the different phases. The baseline set-up is of main interest since it allows discrimination between the induced and the natural CO 2 concentrations variations. The transfer of CO 2 in a carbonate unsaturated zone is varying in function of physical and chemical properties

  6. Amazon rainforest responses to elevated CO2: Deriving model-based hypotheses for the AmazonFACE experiment

    Science.gov (United States)

    Rammig, A.; Fleischer, K.; Lapola, D.; Holm, J.; Hoosbeek, M.

    2017-12-01

    Increasing atmospheric CO2 concentration is assumed to have a stimulating effect ("CO2 fertilization effect") on forest growth and resilience. Empirical evidence, however, for the existence and strength of such a tropical CO2 fertilization effect is scarce and thus a major impediment for constraining the uncertainties in Earth System Model projections. The implications of the tropical CO2 effect are far-reaching, as it strongly influences the global carbon and water cycle, and hence future global climate. In the scope of the Amazon Free Air CO2 Enrichment (FACE) experiment, we addressed these uncertainties by assessing the CO2 fertilization effect at ecosystem scale. AmazonFACE is the first FACE experiment in an old-growth, highly diverse tropical rainforest. Here, we present a priori model-based hypotheses for the experiment derived from a set of 12 ecosystem models. Model simulations identified key uncertainties in our understanding of limiting processes and derived model-based hypotheses of expected ecosystem responses to elevated CO2 that can directly be tested during the experiment. Ambient model simulations compared satisfactorily with in-situ measurements of ecosystem carbon fluxes, as well as carbon, nitrogen, and phosphorus stocks. Models consistently predicted an increase in photosynthesis with elevated CO2, which declined over time due to developing limitations. The conversion of enhanced photosynthesis into biomass, and hence ecosystem carbon sequestration, varied strongly among the models due to different assumptions on nutrient limitation. Models with flexible allocation schemes consistently predicted an increased investment in belowground structures to alleviate nutrient limitation, in turn accelerating turnover rates of soil organic matter. The models diverged on the prediction for carbon accumulation after 10 years of elevated CO2, mainly due to contrasting assumptions in their phosphorus cycle representation. These differences define the expected

  7. Simulating effects of changing climate and CO(2) emissions on soil carbon pools at the Hubbard Brook experimental forest.

    Science.gov (United States)

    Dib, Alain E; Johnson, Chris E; Driscoll, Charles T; Fahey, Timothy J; Hayhoe, Katharine

    2014-05-01

    Carbon (C) sequestration in forest biomass and soils may help decrease regional C footprints and mitigate future climate change. The efficacy of these practices must be verified by monitoring and by approved calculation methods (i.e., models) to be credible in C markets. Two widely used soil organic matter models - CENTURY and RothC - were used to project changes in SOC pools after clear-cutting disturbance, as well as under a range of future climate and atmospheric carbon dioxide (CO(2) ) scenarios. Data from the temperate, predominantly deciduous Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA, were used to parameterize and validate the models. Clear-cutting simulations demonstrated that both models can effectively simulate soil C dynamics in the northern hardwood forest when adequately parameterized. The minimum postharvest SOC predicted by RothC occurred in postharvest year 14 and was within 1.5% of the observed minimum, which occurred in year 8. CENTURY predicted the postharvest minimum SOC to occur in year 45, at a value 6.9% greater than the observed minimum; the slow response of both models to disturbance suggests that they may overestimate the time required to reach new steady-state conditions. Four climate change scenarios were used to simulate future changes in SOC pools. Climate-change simulations predicted increases in SOC by as much as 7% at the end of this century, partially offsetting future CO(2) emissions. This sequestration was the product of enhanced forest productivity, and associated litter input to the soil, due to increased temperature, precipitation and CO(2) . The simulations also suggested that considerable losses of SOC (8-30%) could occur if forest vegetation at HBEF does not respond to changes in climate and CO(2) levels. Therefore, the source/sink behavior of temperate forest soils likely depends on the degree to which forest growth is stimulated by new climate and CO(2) conditions. © 2013 John Wiley & Sons Ltd.

  8. Atmosphere-soil-vegetation model including CO2 exchange processes: SOLVEG2

    International Nuclear Information System (INIS)

    Nagai, Haruyasu

    2004-11-01

    A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO 2 exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO 2 exchanges among the atmosphere, soil, and vegetation. Although the model usually simulates only vertical variation of variables in the surface-layer atmosphere, soil, and vegetation canopy by using meteorological data as top boundary conditions, it can be used by coupling with a three-dimensional atmosphere model. In this paper, details of SOLVEG2, which includes the function of coupling with atmosphere model MM5, are described. (author)

  9. Modeling forest C and N allocation responses to free-air CO2 enrichment

    Science.gov (United States)

    Luus, Kristina; De Kauwe, Martin; Walker, Anthony; Werner, Christian; Iversen, Colleen; McCarthy, Heather; Medlyn, Belinda; Norby, Richard; Oren, Ram; Zak, Donald; Zaehle, Sönke

    2015-04-01

    models to more reliably capture responses of ecosystem C and N allocation to free-air CO2 enrichment because they were able to simulate the priming effect. Insights were therefore gained into between-site differences observed in forest FACE experiments, and the underlying physiological and biogeochemical mechanisms determining ecosystem C and N allocation responses to elevated CO2. References 1. De Kauwe, M. G., et al. (2014), Where does the carbon go? A model-data intercomparison of vegetation carbon allocation and turnover processes at two temperate forest free-air CO2 enrichment sites, New Phytologist, 203, 883-899. 2. Walker, A. P., et al. (2014), Comprehensive ecosystem model-data synthesis using multiple data sets at two temperate forest free-air CO2 enrichment experiments: Model performance at ambient CO2 concentration, Journal of Geophysical Research: Biogeosciences, 119, 937-964. 3. Zaehle, S., et al. (2014), Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies, New Phytologist, 202 (3), 803-822.

  10. Geochemical modelling of worst-case leakage scenarios at potential CO2-storage sites - CO2 and saline water contamination of drinking water aquifers

    Science.gov (United States)

    Szabó, Zsuzsanna; Edit Gál, Nóra; Kun, Éva; Szőcs, Teodóra; Falus, György

    2017-04-01

    Carbon Capture and Storage is a transitional technology to reduce greenhouse gas emissions and to mitigate climate change. Following the implementation and enforcement of the 2009/31/EC Directive in the Hungarian legislation, the Geological and Geophysical Institute of Hungary is required to evaluate the potential CO2 geological storage structures of the country. Basic assessment of these saline water formations has been already performed and the present goal is to extend the studies to the whole of the storage complex and consider the protection of fresh water aquifers of the neighbouring area even in unlikely scenarios when CO2 injection has a much more regional effect than planned. In this work, worst-case scenarios are modelled to understand the effects of CO2 or saline water leaks into drinking water aquifers. The dissolution of CO2 may significantly change the pH of fresh water which induces mineral dissolution and precipitation in the aquifer and therefore, changes in solution composition and even rock porosity. Mobilization of heavy metals may also be of concern. Brine migration from CO2 reservoir and replacement of fresh water in the shallower aquifer may happen due to pressure increase as a consequence of CO2 injection. The saline water causes changes in solution composition which may also induce mineral reactions. The modelling of the above scenarios has happened at several methodological levels such as equilibrium batch, kinetic batch and kinetic reactive transport simulations. All of these have been performed by PHREEQC using the PHREEQC.DAT thermodynamic database. Kinetic models use equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). Reactive transport modelling also considers estimated fluid flow and dispersivity of the studied formation. Further input parameters are the rock and the original ground water compositions of the aquifers and a range of gas-phase CO2 or brine replacement ratios. Worst-case scenarios

  11. Simulation of Transcritical CO2 Refrigeration System with Booster Hot Gas Bypass in Tropical Climate

    Science.gov (United States)

    Santosa, I. D. M. C.; Sudirman; Waisnawa, IGNS; Sunu, PW; Temaja, IW

    2018-01-01

    A Simulation computer becomes significant important for performance analysis since there is high cost and time allocation to build an experimental rig, especially for CO2 refrigeration system. Besides, to modify the rig also need additional cos and time. One of computer program simulation that is very eligible to refrigeration system is Engineering Equation System (EES). In term of CO2 refrigeration system, environmental issues becomes priority on the refrigeration system development since the Carbon dioxide (CO2) is natural and clean refrigerant. This study aims is to analysis the EES simulation effectiveness to perform CO2 transcritical refrigeration system with booster hot gas bypass in high outdoor temperature. The research was carried out by theoretical study and numerical analysis of the refrigeration system using the EES program. Data input and simulation validation were obtained from experimental and secondary data. The result showed that the coefficient of performance (COP) decreased gradually with the outdoor temperature variation increasing. The results show the program can calculate the performance of the refrigeration system with quick running time and accurate. So, it will be significant important for the preliminary reference to improve the CO2 refrigeration system design for the hot climate temperature.

  12. CO2/H2 separation using a highly permeable polyurethane membrane: Molecular dynamics simulation

    Science.gov (United States)

    Azizi, Morteza; Mousavi, Seyyed Abbas

    2015-11-01

    In this study, Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations were conducted to investigate the diffusivity, solubility, and permeability of CO2, CO, H2, and H2O in a polyurethane membrane at three different temperatures. The characterization of the simulated structures was carried out using XRD, FFV, Tg and density calculation, and cavity size distribution. The obtained results were within the expectations reported data in the literature based on the experimental approach, indicating the authenticity of approached in this work. The results showed that the highest diffusivity and permeability coefficients were observed for H2; while the highest values of solubility coefficient were found for H2O and CO2 gases. The increase of operating temperature from 298 K to 318 K has a positive effect on the permeation of all gases and a corresponding negative effect on the selectivity of the gas pair CO2/H2. Also, the results vividly showed that CO2 and H2O gases have a profound affinity with hard phase of polyurethane, while H2 and CO were conversely adsorbed by soft one. Moreover, the enhancement of permeability and permselectivity of CO2/H2 pair confirmed using Robeson Upper-Bond graph showed its good capacity for CO2/H2 separation application.

  13. Pore-scale modeling of wettability effects on CO2-brine displacement during geological storage

    Science.gov (United States)

    Basirat, Farzad; Yang, Zhibing; Niemi, Auli

    2017-11-01

    Wetting properties of reservoir rocks and caprocks can vary significantly, and they strongly influence geological storage of carbon dioxide in deep saline aquifers, during which CO2 is supposed to displace the resident brine and to become permanently trapped. Fundamental understanding of the effect of wettability on CO2-brine displacement is thus important for improving storage efficiency and security. In this study, we investigate the influence of wetting properties on two-phase flow of CO2 and brine at the pore scale. A numerical model based on the phase field method is implemented to simulate the two-phase flow of CO2-brine in a realistic pore geometry. Our focus is to study the pore-scale fluid-fluid displacement mechanisms under different wetting conditions and to quantify the effect of wettability on macroscopic parameters such as residual brine saturation, capillary pressure, relative permeability, and specific interfacial area. Our simulation results confirm that both the trapped wetting phase saturation and the normalized interfacial area increase with decreasing contact angle. However, the wetting condition does not appear to influence the CO2 breakthrough time and saturation. We also show that the macroscopic capillary pressures based on the pressure difference between inlet and outlet can differ significantly from the phase averaging capillary pressures for all contact angles when the capillary number is high (log Ca > -5). This indicates that the inlet-outlet pressure difference may not be a good measure of the continuum-scale capillary pressure. In addition, the results show that the relative permeability of CO2 can be significantly lower in strongly water-wet conditions than in the intermediate-wet conditions.

  14. Fast Cloud Adjustment to Increasing CO2 in a Superparameterized Climate Model

    Directory of Open Access Journals (Sweden)

    Marat Khairoutdinov

    2012-05-01

    Full Text Available Two-year simulation experiments with a superparameterized climate model, SP-CAM, are performed to understand the fast tropical (30S-30N cloud response to an instantaneous quadrupling of CO2 concentration with SST held fixed at present-day values.The greenhouse effect of the CO2 perturbation quickly warms the tropical land surfaces by an average of 0.5 K. This shifts rising motion, surface precipitation, and cloud cover at all levels from the ocean to the land, with only small net tropical-mean cloud changes. There is a widespread average reduction of about 80 m in the depth of the trade inversion capping the marine boundary layer (MBL over the cooler subtropical oceans.One apparent contributing factor is CO2-enhanced downwelling longwave radiation, which reduces boundary-layer radiative cooling, a primary driver of turbulent entrainment through the trade inversion. A second contributor is a slight CO2-induced heating of the free troposphere above the MBL, which strengthens the trade inversion and also inhibits entrainment. There is a corresponding downward displacement of MBL clouds with a very slight decrease in mean cloud cover and albedo.Two-dimensional cloud-resolving model (CRM simulations of this MBL response are run to steady state using composite SP-CAM simulated thermodynamic and wind profiles from a representative cool subtropical ocean regime, for the control and 4xCO2 cases. Simulations with a CRM grid resolution equal to that of SP-CAM are compared with much finer resolution simulations. The coarse-resolution simulations maintain a cloud fraction and albedo comparable to SP-CAM, but the fine-resolution simulations have a much smaller cloud fraction. Nevertheless, both CRM configurations simulate a reduction in inversion height comparable to SP-CAM. The changes in low cloud cover and albedo in the CRM simulations are small, but both simulations predict a slight reduction in low cloud albedo as in SP-CAM.

  15. Numerical Simulations for Enhanced Methane Recovery from Gas Hydrate Accumulations by Utilizing CO2 Sequestration

    Science.gov (United States)

    Sridhara, Prathyusha

    In 2013, the International Energy Outlook (EIA, 2013) projected that global energy demand will grow by 56% between 2010 and 2040. Despite strong growth in renewable energy supplies, much of this growth is expected to be met by fossil fuels. Concerns ranging from greenhouse gas emissions and energy security are spawning new interests for other sources of energy including renewable and unconventional fossil fuel such as shale gas and oil as well as gas hydrates. The production methods as well as long-term reservoir behavior of gas hydrate deposits have been under extensive investigation. Reservoir simulators can be used to predict the production potentials of hydrate formations and to determine which technique results in enhanced gas recovery. In this work, a new simulation tool, Mix3HydrateResSim (Mix3HRS), which accounts for complex thermodynamics of multi-component hydrate phase comprised of varying hydrate solid crystal structure, is used to perform the CO2-assisted production technique simulations from CH4 hydrate accumulations. The simulator is one among very few reservoir simulators which can simulate the process of CH4 substitution by CO2 (and N2 ) in the hydrate lattice. Natural gas hydrate deposits around the globe are categorized into three different classes based on the characteristics of the geological sediments present in contact with the hydrate bearing deposits. Amongst these, the Class 2 hydrate accumulations predominantly confirmed in the permafrost and along seashore, are characterized by a mobile aqueous phase underneath a hydrate bearing sediment. The exploitation of such gas hydrate deposits results in release of large amounts of water due to the presence of permeable water-saturated sediments encompassing the hydrate deposits, thus lowering the produced gas rates. In this study, a suite of numerical simulation scenarios with varied complexity are considered which aimed at understanding the underlying changes in physical, thermodynamic and

  16. Geochemical modeling of fluid-fluid and fluid-mineral interactions during geological CO2 storage

    Science.gov (United States)

    Zhu, C.; Ji, X.; Lu, P.

    2013-12-01

    The long time required for effective CO2 storage makes geochemical modeling an indispensable tool for CCUS. One area of geochemical modeling research that is in urgent need is impurities in CO2 streams. Permitting impurities, such as H2S, in CO2 streams can lead to potential capital and energy savings. However, predicting the consequences of co-injection of CO2 and impurities into geological formations requires the understanding of the phase equilibrium and fluid-fluid interactions. To meet this need, we developed a statistical associating fluid theory (SAFT)-based equation of state (EOS) for the H2S-CO2-H2O-NaCl system at 373.15 concentration of NaCl up to 6 mol/kgH2O. The EoS allows us to predict equilibrium composition in both liquid and vapor phases, fugacity coefficients of components, and phase densities. Predictions show that inclusion of H2S in CO2 streams may lead to two-phase flow in pipelines. For H2S-CO2 mixtures at a given temperature the bubble and dew pressures decrease with increasing H2S content, while the mass density increases at low pressures and decreases at high pressures. Furthermore, the EoS can be incorporated into reservoir simulators so that the dynamic development of mixed fluid plumes in the reservoir can be simulated. Accurate modeling of fluid-mineral interactions must confront unresolved uncertainties of silicate dissolution - precipitation reaction kinetics. Most prominent among these uncertainties is the well-known lab-field apparent discrepancy in dissolution rates. Although reactive transport models that simulate the interactions between reservoir rocks and brine, and their attendant effects on porosity and permeability changes, have proliferated, whether these results have acceptable uncertainties are unknown. We have conducted a series of batch experiments at elevated temperatures and numerical simulations of coupled dissolution and precipitation reactions. The results show that taking into account of reaction coupling is able

  17. Data and modelling requirements for CO2 inversions using high-frequency data

    International Nuclear Information System (INIS)

    Law, R.M.; Rayner, P.J.; Steele, L.P.; Enting, I.G.

    2003-01-01

    We explore the future possibilities for CO 2 source estimation from atmospheric concentration data by performing synthetic data experiments. Synthetic data are used to test seasonal CO 2 inversions using high-frequency data. Monthly CO 2 sources over the Australian region are calculated for inversions with data at 4-hourly frequency and averaged over 1 d, 2.5 d, 5 d, 12.17 d and 1 month. The inversion quality, as determined by bias and uncertainty, is degraded when averaging over longer periods. This shows the value of the strong but relatively short-lived signals present in high-frequency records that are removed in averaged and particularly filtered records. Sensitivity tests are performed in which the synthetic data are 'corrupted' to simulate systematic measurement errors such as intercalibration differences or to simulate transport modelling errors. The inversion is also used to estimate the effect of calibration offsets between sites. We find that at short data-averaging periods the inversion is reasonably robust to measurement-type errors. For transport-type errors, the best results are achieved for synoptic (2-5 d) timescales. Overall the tests indicate that improved source estimates should be possible by incorporating continuous measurements into CO 2 inversions

  18. Modeling of CO2 Solubility in Aqueous Potassium Lysinate Solutions at Post-Combustion CO2 Capture Conditions

    Science.gov (United States)

    Bian, Y.; Shen, S.

    2017-05-01

    Aqueous potassium lysinate (LysK) has been proposed as an alternative to aqueous alkanolamines for CO2 capture due to fast kinetics and large absorption capacity. However, thermodynamic modeling for aqueous LysK system has not been available yet. In this work, a modified Kent-Eisenberg model with correlated equilibrium constants was developed to interpret the vapor-liquid equilibrium (VLE) data at postcombustion capture conditions. The predictions from the developed model are in good agreement with the experimental results with AAD within 19 %.

  19. Evaluating the uncertainty in geochemical modelling for CO2 storage. The example of Ketzin.

    Science.gov (United States)

    De Lucia, Marco; Audigane, Pascal; Jacquemet, Nicolas; Kühn, Michael

    2010-05-01

    Several sources of uncertainty are associated with geochemical modelling of reservoirs considered for CO2 storage : on one hand only few available data are generally available for a particular reservoir, which are affected by measure errors, and whose representativity is in most cases questionable; on the other hand, the phenomenological description itself of the chemical fluid-rock interactions relies heavily on experimental determination of physical observables, which are summarized in a thermodynamical and chemical databases used by the numerical simulators. The latter is for example the case of the CO2 disposal in saline aquifer, where the high ionic strength of the formation fluid requires a Pitzer ion interaction model to evaluate with sufficient accuracy the activities of the considered species. Typically, parameters for Pitzer model are discordant following different authors and data related to a conspicous number of relevant ions are often unavailable or unreliable -i.e. derived for different P/T conditions or ionic strength of the solution -, which makes very difficult to estimate the accuracy of the predictions. This contribution presents our effort in evaluating the reliability of chemical simulations in the case of Ketzin on-shore CO2 storage project. Based on available fluid and mineralogic analysis, an initial equilibrium model was determined, i.e. matching both the observed fluid composition and the saturation with the mineral phases present in the sandstone layer of the Stuttgart formation which constitutes the reservoir. A sensitivity analisys based on small perturbations of such initial model was then performed, in order to assess the influence of measurement errors and possibly define a compositional range which can be assumed in spatially variable simulations. This step is then followed by the sensitivity to the Pitzer parameters that are collected in the chemical database used throughout this study; both the parameters themselves and their

  20. Applicability of aquifer impact models to support decisions at CO2 sequestration sites

    Energy Technology Data Exchange (ETDEWEB)

    Keating, Elizabeth; Bacon, Diana; Carroll, Susan; Mansoor, Kayyum; Sun, Yunwei; Zheng, Liange; Harp, Dylan; Dai, Zhenxue

    2016-09-01

    The National Risk Assessment Partnership has developed a suite of tools to assess and manage risk at CO2 sequestration sites (www.netldoe.gov/nrap). This capability includes polynomial or look-up table based reduced-order models (ROMs) that predict the impact of CO2 and brine leaks on overlying aquifers. The development of these computationally-efficient models and the underlying reactive transport simulations they emulate has been documented elsewhere (Carroll et al., 2014, Dai et al., 2014, Keating et al., 2015). The ROMs reproduce the ensemble behavior of large numbers of simulations and are well-suited to applications that consider a large number of scenarios to understand parameter sensitivity and uncertainty on the risk of CO2 leakage to groundwater quality. In this paper, we seek to demonstrate applicability of ROM-based ensemble analysis by considering what types of decisions and aquifer types would benefit from the ROM analysis. We present four hypothetical four examples where applying ROMs, in ensemble mode, could support decisions in the early stages in a geologic CO2 sequestration project. These decisions pertain to site selection, site characterization, monitoring network evaluation, and health impacts. In all cases, we consider potential brine/CO2 leak rates at the base of the aquifer to be uncertain. We show that derived probabilities provide information relevant to the decision at hand. Although the ROMs were developed using site-specific data from two aquifers (High Plains and Edwards), the models accept aquifer characteristics as variable inputs and so they may have more broad applicability. We conclude that pH and TDS predictions are the most transferable to other aquifers based on the analysis of the nine water quality metrics (pH, TDS, 4 trace metals, 3 organic compounds). Guidelines are presented for determining the aquifer types for which the ROMs should be applicable.

  1. Utilization of Integrated Assessment Modeling for determining geologic CO2 storage security

    Science.gov (United States)

    Pawar, R.

    2017-12-01

    Geologic storage of carbon dioxide (CO2) has been extensively studied as a potential technology to mitigate atmospheric concentration of CO2. Multiple international research & development efforts, large-scale demonstration and commercial projects are helping advance the technology. One of the critical areas of active investigation is prediction of long-term CO2 storage security and risks. A quantitative methodology for predicting a storage site's long-term performance is critical for making key decisions necessary for successful deployment of commercial scale projects where projects will require quantitative assessments of potential long-term liabilities. These predictions are challenging given that they require simulating CO2 and in-situ fluid movements as well as interactions through the primary storage reservoir, potential leakage pathways (such as wellbores, faults, etc.) and shallow resources such as groundwater aquifers. They need to take into account the inherent variability and uncertainties at geologic sites. This talk will provide an overview of an approach based on integrated assessment modeling (IAM) to predict long-term performance of a geologic storage site including, storage reservoir, potential leakage pathways and shallow groundwater aquifers. The approach utilizes reduced order models (ROMs) to capture the complex physical/chemical interactions resulting due to CO2 movement and interactions but are computationally extremely efficient. Applicability of the approach will be demonstrated through examples that are focused on key storage security questions such as what is the probability of leakage of CO2 from a storage reservoir? how does storage security vary for different geologic environments and operational conditions? how site parameter variability and uncertainties affect storage security, etc.

  2. Interannual Variability In the Atmospheric CO2 Rectification Over Boreal Forests Based On A Coupled Ecosystem-Atmosphere Model

    Science.gov (United States)

    Chen, B.; Chen, J. M.; Worthy, D.

    2004-05-01

    Ecosystem CO2 exchange and the planetary boundary layer (PBL) are correlated diurnally and seasonally. The simulation of this atmospheric rectifier effect is important in understanding the global CO2 distribution pattern. A 12-year (1990-1996, 1999-2003), continuous CO2 measurement record from Fraserdale, Ontario (located ~150 km north of Timmons), along with a coupled Vertical Diffusion Scheme (VDS) and ecosystem model (Boreal Ecosystem Productivity Simulator, BEPS), is used to investigate the interannual variability in this effect over a boreal forest region. The coupled model performed well in simulating CO2 vertical diffusion processes. Simulated annual atmospheric rectifier effects, (including seasonal and diurnal), quantified as the variation in the mean CO2 concentration from the surface to the top of the PBL, varied from 2.8 to 4.1 ppm, even though the modeled seasonal variations in the PBL depth were similar throughout the 12-year period. The differences in the interannual rectifier effect primarily resulted from changes in the biospheric CO2 uptake and heterotrophic respiration. Correlations in the year-to year variations of the CO2 rectification were found with mean annual air temperatures, simulated gross primary productivity (GPP) and heterotrophic respiration (Rh) (r2=0.5, 0.46, 0.42, respectively). A small increasing trend in the CO2 rectification was also observed. The year-to-year variation in the vertical distribution of the monthly mean CO2 mixing ratios (reflecting differences in the diurnal rectifier effect) was related to interannual climate variability, however, the seasonal rectifier effects were found to be more sensitive to climate variability than the diurnal rectifier effects.

  3. Assessment of model estimates of land-atmosphere CO2 exchange across Northern Eurasia

    Science.gov (United States)

    Rawlins, M. A.; McGuire, A. D.; Kimball, J. S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D. P.; Miller, P.; Moore, J. C.; Smith, B.; Sueyoshi, T.

    2015-07-01

    A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960-2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m-2 yr-2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960-1969 vs. 2000-2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model elements

  4. Atmospheric CO2 observations and models suggest strong carbon uptake by forests in New Zealand

    Science.gov (United States)

    Steinkamp, Kay; Mikaloff Fletcher, Sara E.; Brailsford, Gordon; Smale, Dan; Moore, Stuart; Keller, Elizabeth D.; Baisden, W. Troy; Mukai, Hitoshi; Stephens, Britton B.

    2017-01-01

    A regional atmospheric inversion method has been developed to determine the spatial and temporal distribution of CO2 sinks and sources across New Zealand for 2011-2013. This approach infers net air-sea and air-land CO2 fluxes from measurement records, using back-trajectory simulations from the Numerical Atmospheric dispersion Modelling Environment (NAME) Lagrangian dispersion model, driven by meteorology from the New Zealand Limited Area Model (NZLAM) weather prediction model. The inversion uses in situ measurements from two fixed sites, Baring Head on the southern tip of New Zealand's North Island (41.408° S, 174.871° E) and Lauder from the central South Island (45.038° S, 169.684° E), and ship board data from monthly cruises between Japan, New Zealand, and Australia. A range of scenarios is used to assess the sensitivity of the inversion method to underlying assumptions and to ensure robustness of the results. The results indicate a strong seasonal cycle in terrestrial land fluxes from the South Island of New Zealand, especially in western regions covered by indigenous forest, suggesting higher photosynthetic and respiratory activity than is evident in the current a priori land process model. On the annual scale, the terrestrial biosphere in New Zealand is estimated to be a net CO2 sink, removing 98 (±37) Tg CO2 yr-1 from the atmosphere on average during 2011-2013. This sink is much larger than the reported 27 Tg CO2 yr-1 from the national inventory for the same time period. The difference can be partially reconciled when factors related to forest and agricultural management and exports, fossil fuel emission estimates, hydrologic fluxes, and soil carbon change are considered, but some differences are likely to remain. Baseline uncertainty, model transport uncertainty, and limited sensitivity to the northern half of the North Island are the main contributors to flux uncertainty.

  5. Biogeochemical modeling of CO2 and CH4 production in anoxic Arctic soil microcosms

    Science.gov (United States)

    Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; Yang, Ziming; Graham, David E.; Gu, Baohua; Painter, Scott L.; Thornton, Peter E.

    2016-09-01

    Soil organic carbon turnover to CO2 and CH4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO2 solubility as pH increases, and taking into account CO2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO2 production from closed microcosms can be substantially underestimated based on headspace CO2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.

  6. Vertically-Integrated Dual-Continuum Models for CO2 Injection in Fractured Aquifers

    Science.gov (United States)

    Tao, Y.; Guo, B.; Bandilla, K.; Celia, M. A.

    2017-12-01

    Injection of CO2 into a saline aquifer leads to a two-phase flow system, with supercritical CO2 and brine being the two fluid phases. Various modeling approaches, including fully three-dimensional (3D) models and vertical-equilibrium (VE) models, have been used to study the system. Almost all of that work has focused on unfractured formations. 3D models solve the governing equations in three dimensions and are applicable to generic geological formations. VE models assume rapid and complete buoyant segregation of the two fluid phases, resulting in vertical pressure equilibrium and allowing integration of the governing equations in the vertical dimension. This reduction in dimensionality makes VE models computationally more efficient, but the associated assumptions restrict the applicability of VE model to formations with moderate to high permeability. In this presentation, we extend the VE and 3D models for CO2 injection in fractured aquifers. This is done in the context of dual-continuum modeling, where the fractured formation is modeled as an overlap of two continuous domains, one representing the fractures and the other representing the rock matrix. Both domains are treated as porous media continua and can be modeled by either a VE or a 3D formulation. The transfer of fluid mass between rock matrix and fractures is represented by a mass transfer function connecting the two domains. We have developed a computational model that combines the VE and 3D models, where we use the VE model in the fractures, which typically have high permeability, and the 3D model in the less permeable rock matrix. A new mass transfer function is derived, which couples the VE and 3D models. The coupled VE-3D model can simulate CO2 injection and migration in fractured aquifers. Results from this model compare well with a full-3D model in which both the fractures and rock matrix are modeled with 3D models, with the hybrid VE-3D model having significantly reduced computational cost. In

  7. Reservoir simulation with the cubic plus (cross-) association equation of state for water, CO2, hydrocarbons, and tracers

    Science.gov (United States)

    Moortgat, Joachim

    2018-04-01

    This work presents an efficient reservoir simulation framework for multicomponent, multiphase, compressible flow, based on the cubic-plus-association (CPA) equation of state (EOS). CPA is an accurate EOS for mixtures that contain non-polar hydrocarbons, self-associating polar water, and cross-associating molecules like methane, ethane, unsaturated hydrocarbons, CO2, and H2S. While CPA is accurate, its mathematical formulation is highly non-linear, resulting in excessive computational costs that have made the EOS unfeasible for large scale reservoir simulations. This work presents algorithms that overcome these bottlenecks and achieve an efficiency comparable to the much simpler cubic EOS approach. The main applications that require such accurate phase behavior modeling are 1) the study of methane leakage from high-pressure production wells and its potential impact on groundwater resources, 2) modeling of geological CO2 sequestration in brine aquifers when one is interested in more than the CO2 and H2O components, e.g. methane, other light hydrocarbons, and various tracers, and 3) enhanced oil recovery by CO2 injection in reservoirs that have previously been waterflooded or contain connate water. We present numerical examples of all those scenarios, extensive validation of the CPA EOS with experimental data, and analyses of the efficiency of our proposed numerical schemes. The accuracy, efficiency, and robustness of the presented phase split computations pave the way to more widespread adoption of CPA in reservoir simulators.

  8. Wettability-Water/brine Film Thickness Relationship and the Effect of Supercritical CO2 Pre-contact for CO2/brine/mineral Systems under Geologic CO2 Sequestration Conditions: Insights from Molecular Dynamics Simulations

    Science.gov (United States)

    Chen, C.; Song, Y.; Li, W.

    2016-12-01

    Injection CO2 into deep saline aquifers is one of the main options for geologic carbon sequestration (GCS). A successful GCS in saline aquifers requires full knowledge about CO2/brine/mineral systems under sequestration conditions to reduce uncertainties during subsurface storage of CO2. Adsorbed water film thickness and wettability on mineral surfaces are two key characteristics for CO2/brine/mineral systems. Wettability and water/brine film thickness have been measured experimentally and predicted by molecular simulation (MD) studies. However, these studies only consider the films apart from contact angles. Investigations on wettability for CO2/brine/mineral systems only consider contact angles without measurements on film thickness. The relationship between film thicknesses with water contact angles is open to questions. In this paper, MD simulations have been performed to investigate the interrelationship between water film thicknesses and water contact angles. Three silica surfaces with different silanol group number densities (Q3, Q3-50%, Q3/Q4) were selected to represent silica surfaces with different wettabilities. We found that as water contact angle increases, the film thickness decreases. We also studied the effect of CO2-mineral pre-contact and found that: on Q3 surface, if a CO2 bubble was pre-contacted with the surface, it can remain on the surface without forming a water film; however, if a CO2 bubble was placed certain distances away from the surface, it formed a water film. Wettability analysis revealed that on the same surface, water contact angle was larger when there was no water film. These findings show that on some silica surfaces, water film may be destroyed by supercritical CO2 even the silica surfaces are hydrophilic. A water film rupture mechanism was propsed for CO2 adhesion on mineral surfaces [Wang (2013) Environ. Sci. Technol. 47, 11858; Zhang (2016) Environ. Sci. Technol. Lett. 10.1021/acs.estlett.5b00359]. The rupture of water film

  9. Density-Driven Flow Simulation in Anisotropic Porous Media: Application to CO2 Geological Sequestration

    KAUST Repository

    Negara, Ardiansyah

    2014-04-21

    Carbon dioxide (CO2) sequestration in saline aquifers is considered as one of the most viable and promising ways to reduce CO2 concentration in the atmosphere. CO2 is injected into deep saline formations at supercritical state where its density is smaller than the hosting brine. This motivates an upward motion and eventually CO2 is trapped beneath the cap rock. The trapped CO2 slowly dissolves into the brine causing the density of the mixture to become larger than the host brine. This causes gravitational instabilities that is propagated and magnified with time. In this kind of density-driven flows, the CO2-rich brines migrate downward while the brines with low CO2 concentration move upward. With respect to the properties of the subsurface aquifers, there are instances where saline formations can possess anisotropy with respect to their hydraulic properties. Such anisotropy can have significant effect on the onset and propagation of flow instabilities. Anisotropy is predicted to be more influential in dictating the direction of the convective flow. To account for permeability anisotropy, the method of multipoint flux approximation (MPFA) in the framework of finite differences schemes is used. The MPFA method requires more point stencil than the traditional two-point flux approximation (TPFA). For example, calculation of one flux component requires 6-point stencil and 18-point stencil in 2-D and 3-D cases, respectively. As consequence, the matrix of coefficient for obtaining the pressure fields will be quite complex. Therefore, we combine the MPFA method with the experimenting pressure field technique in which the problem is reduced to solving multitude of local problems and the global matrix of coefficients is constructed automatically, which significantly reduces the complexity. We present several numerical scenarios of density-driven flow simulation in homogeneous, layered, and heterogeneous anisotropic porous media. The numerical results emphasize the

  10. Co2 emission scenarios for next centuries to obtain more complete simulations of the global warming

    International Nuclear Information System (INIS)

    Michelini, M.

    2001-01-01

    In the framework of a punctual Modeling of the Greenhouse Effect (report RT/ERG/2001/1) it is necessary to set CO2 Emission Scenarios for the next Centuries in order to obtain the complete evolution of the global warming. Some methodologies are described to approach such long term previsions. From the demand side, the growth of the consumes (which are affected by population and development) is correlated (supply side) with the technical-economic-environmental Evaluation of the future diffusion of classic sources (experienced in the past centuries) and of new Technologies and renewable sources. The previsions of the world population Growth are derived from the UNFPA publications. The degree of economic Development of the world Population in the very long term is obtained by simulating the Evolution of the Population across four main Areas characterized by different pro-capita consumes. Using these criteria two different Scenarios have been set-up and put into comparison with the SRES Scenarios published in the Third Assessment Report-WG1 of the IPCC. The cut at the year 2100 of the SRES Scenarios is also discussed. Simulations of the Global Warming in the long term have been performed with the two scenarios. These results are discussed together with the results of the Simulations reported by IPCC [it

  11. The CO2 emission permits market simulation using Continuous Double Auction

    International Nuclear Information System (INIS)

    Bartoszczuk, Pawel; Stanczak, Jaroslaw

    2016-01-01

    In this paper we consider the buying and selling prices of carbon dioxide (CO 2 ) emission permits in trading models with uncertainty. Permission prices, although usually omitted from standard models, may significantly influence the trading market. We thus construct a more realistic trade model. To do this, we introduced several important changes to the standard model, mainly we added The Continuous Double Action.

  12. Simulation of CO 2 concentrations at Tsukuba tall tower using WRF ...

    Indian Academy of Sciences (India)

    Simulation of carbon dioxide (CO2) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal ... Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations ...

  13. Hollow Fiber Membrane Contactors for CO2 Capture: Modeling and Up-Scaling to CO2 Capture for an 800 MWe Coal Power Station

    Directory of Open Access Journals (Sweden)

    Kimball Erin

    2014-11-01

    Full Text Available A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM with the more conventional structured packing columns as the absorber in amine-based CO2 capture systems for power plants. In order to simulate the operation of industrial scale HFMM systems, a two-dimensional model was developed and validated based on results of a laboratory scale HFMM. After successful experiments and validation of the model, a pilot scale HFMM was constructed and simulated with the same model. The results of the simulations, from both sizes of HFMM, were used to assess the feasibility of further up-scaling to a HFMM system to capture the CO2 from an 800 MWe power plant. The system requirements – membrane fiber length, total contact surface area, and module volume – were determined from simulations and used for an economic comparison with structured packing columns. Results showed that a significant cost reduction of at least 50% is required to make HFMM competitive with structured packing columns. Several factors for the design of industrial scale HFMM require further investigation, such as the optimal aspect ratio (module length/diameter, membrane lifetime, and casing material and shape, in addition to the need to reduce the overall cost. However, HFMM were also shown to have the advantages of having a higher contact surface area per unit volume and modular scale-up, key factors for applications requiring limited footprints or flexibility in configuration.

  14. Thermogravimetric and model-free kinetic studies on CO2 ...

    Indian Academy of Sciences (India)

    some low-quality NER Indian coal samples in CO2 atmosphere, and also to evaluate the effect of coal properties on gasification reactivity. These results generated will be useful in formulating the gasifi- cation technology not only for NER coals but also for other low-quality coals of the world. 2. Materials and methods.

  15. Energy from CO2 using capacitive electrodes – A model for energy extraction cycles

    NARCIS (Netherlands)

    Paz-García, J.M.; Dykstra, J.E.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    A model is presented for the process of harvesting electrical energy from CO2 emissions using capacitive cells. The principle consists of controlling the mixing process of a concentrated CO2 gas stream with a dilute CO2 gas stream (as, for example, exhaust gas and air), thereby converting part of

  16. Probabilistic modelling of rock damage: application to geological storage of CO2

    International Nuclear Information System (INIS)

    Guy, N.

    2010-01-01

    The storage of CO 2 in deep geological formations is considered as a possible way to reduce emissions of greenhouse gases in the atmosphere. The condition of the rocks constituting the reservoir is a key parameter on which rely both storage safety and efficiency. The objective of this thesis is to characterize the risks generated by a possible change of mechanical and transfer properties of the material of the basement after an injection of CO 2 . Large-scale simulations aiming at representing the process of injection of CO 2 at the supercritical state into an underground reservoir were performed. An analysis of the obtained stress fields shows the possibility of generating various forms of material degradation for high injection rates. The work is devoted to the study of the emergence of opened cracks. Following an analytical and simplified study of the initiation and growth of opened cracks based on a probabilistic model, it is shown that the formation of a crack network is possible. The focus is then to develop in the finite element code Code Aster a numerical tool to simulate the formation of crack networks. A nonlocal model based on stress regularization is proposed. A test on the stress intensity factor is used to describe crack propagation. The initiation of new cracks is modeled by a Poisson-Weibull process. The used parameters are identified by an experimental campaign conducted on samples from an actual geological site for CO 2 storage. The model developed is then validated on numerical cases, and also against experimental results carried out herein. (author)

  17. High-Throughput Molecular Simulations of Metal Organic Frameworks for CO2 Separation: Opportunities and Challenges

    Directory of Open Access Journals (Sweden)

    Ilknur Erucar

    2018-02-01

    Full Text Available Metal organic frameworks (MOFs have emerged as great alternatives to traditional nanoporous materials for CO2 separation applications. MOFs are porous materials that are formed by self-assembly of transition metals and organic ligands. The most important advantage of MOFs over well-known porous materials is the possibility to generate multiple materials with varying structural properties and chemical functionalities by changing the combination of metal centers and organic linkers during the synthesis. This leads to a large diversity of materials with various pore sizes and shapes that can be efficiently used for CO2 separations. Since the number of synthesized MOFs has already reached to several thousand, experimental investigation of each MOF at the lab-scale is not practical. High-throughput computational screening of MOFs is a great opportunity to identify the best materials for CO2 separation and to gain molecular-level insights into the structure–performance relationships. This type of knowledge can be used to design new materials with the desired structural features that can lead to extraordinarily high CO2 selectivities. In this mini-review, we focused on developments in high-throughput molecular simulations of MOFs for CO2 separations. After reviewing the current studies on this topic, we discussed the opportunities and challenges in the field and addressed the potential future developments.

  18. Observing System Simulations for the NASA ASCENDS Lidar CO2 Mission Concept: Substantiating Science Measurement Requirements

    Science.gov (United States)

    Kawa, Stephan R.; Baker, David Frank; Schuh, Andrew E.; Abshire, James Brice; Browell, Edward V.; Michalak, Anna M.

    2012-01-01

    The NASA ASCENDS mission (Active Sensing of Carbon Emissions, Nights, Days, and Seasons) is envisioned as the next generation of dedicated, space-based CO2 observing systems, currently planned for launch in about the year 2022. Recommended by the US National Academy of Sciences Decadal Survey, active (lidar) sensing of CO2 from space has several potentially significant advantages, in comparison to current and planned passive CO2 instruments, that promise to advance CO2 measurement capability and carbon cycle understanding into the next decade. Assessment and testing of possible lidar instrument technologies indicates that such sensors are more than feasible, however, the measurement precision and accuracy requirements remain at unprecedented levels of stringency. It is, therefore, important to quantitatively and consistently evaluate the measurement capabilities and requirements for the prospective active system in the context of advancing our knowledge of carbon flux distributions and their dependence on underlying physical processes. This amounts to establishing minimum requirements for precision, relative accuracy, spatial/temporal coverage and resolution, vertical information content, interferences, and possibly the tradeoffs among these parameters, while at the same time framing a mission that can be implemented within a constrained budget. Here, we present results of observing system simulation studies, commissioned by the ASCENDS Science Requirements Definition Team, for a range of possible mission implementation options that are intended to substantiate science measurement requirements for a laser-based CO2 space instrument.

  19. Validation on wheat response to irrigation, CO2 and nitrogen fertilization in the Community Land Model

    Science.gov (United States)

    Lu, Y.

    2016-12-01

    Wheat is a staple crop for global food security, and is the dominant vegetation cover for a significant fraction of earth's croplands. As such, it plays an important role in soil carbon balance, and land-atmosphere interactions in these key regions. Understanding whether the Community Land Model (CLM) appropriate response to elevated CO2 and different levels of nitrogen fertilization and irrigation is a crucial question. We participated the AgMIP-wheat project and run 72 simulations at Maricopa spring wheat FACE sites and five winter wheat sites in North America forcing with site observed meteorology data. After calibration on the phenology, carbon allocation, and soil hydrology parameters, wheat in CLM45 has reasonable response to irrigation and elevated CO2. However, wheat in CLM45 has no response to low or high N fertilization because the low amount of N fertilization is sufficient for wheat growth in CLM45. We plan to further extend the same simulations for CLM5 (will release in Fall 2016), which has substantial improvements on soil hydrology (improved soil evaporation and plant hydraulic parameterization) and nitrogen dynamics (flexible leaf CN ratio and Vcmax25, plant pays for carbon to get nitrogen). We will evaluate the uncertainties of wheat response to nitrogen fertilization, irrigation, CO2 due to model improvements.

  20. Transpiration and CO2 fluxes of a pine forest: modelling the undergrowth effect

    Directory of Open Access Journals (Sweden)

    V. Rivalland

    2005-02-01

    Full Text Available A modelling study is performed in order to quantify the relative effect of allowing for the physiological properties of an undergrowth grass sward on total canopy water and carbon fluxes of the Le-Bray forest (Les-Landes, South-western France. The Le-Bray forest consists of maritime pine and an herbaceous undergrowth (purple moor-grass, which is characterised by a low stomatal control of transpiration, in contrast to maritime pine. A CO2-responsive land surface model is used that includes responses of woody and herbaceous species to water stress. An attempt is made to represent the properties of the undergrowth vegetation in the land surface model Interactions between Soil, Biosphere, and Atmosphere, CO2-responsive, ISBA-A-gs. The new adjustment allows for a fairly different environmental response between the forest canopy and the understory in a simple manner. The model's simulations are compared with long term (1997 and 1998 micro-meteorological measurements over the Le-Bray site. The fluxes of energy, water and CO2, are simulated with and without the improved representation of the undergrowth vegetation, and the two simulations are compared with the observations. Accounting for the undergrowth permits one to improve the model's scores. A simple sensitivity experiment shows the behaviour of the model in response to climate change conditions, and the understory effect on the water balance and carbon storage of the forest. Accounting for the distinct characteristics of the undergrowth has a substantial and positive effect on the model accuracy and leads to a different response to climate change scenarios.

  1. Geomechanical Characterization and Reservoir Simulation of a CO2-EOR and Sequestration Project in a Mature Oil Field, Teapot Dome, WY

    Science.gov (United States)

    Chiaramonte, L.; Zoback, M. D.; Friedmann, J.; Stamp, V.

    2008-12-01

    Mature oil and gas reservoirs are attractive targets for geological sequestration of CO2 because of their potential storage capacities and the possible cost offsets from enhanced oil recovery (EOR). In this work we develop a 3D reservoir model and fluid flow simulation of the Tensleep Formation using geomechanical constraints in advance of a proposed CO2-EOR injection experiment at Teapot Dome Oil Field, WY. The objective of this work is to model the migration of the injected CO2 as well as to obtain limits on the rates and volumes of CO2 that can be injected without compromising seal integrity. In the present work we combine our previous geomechanical analysis, geostatistical reservoir modeling and fluid flow simulations to investigate critical questions regarding the feasibility of a CO2-EOR project in the Tensleep Fm. The analysis takes in consideration the initial trapping and sealing mechanisms of the reservoir, the consequences of past and present oil production on these mechanisms, and the potential effect of the CO2 injection on the reservoir and the seal. Finally we also want to assess the long-term recovery of the injection site and what will happen in the system once the oil production stops. The CO2-EOR injection pilot will consist of the injection of 1 MMcfd of supercritical CO2 for six weeks. The preliminary simulation results indicate that the injected CO2 will rapidly rise to the top layers, above the main producing interval, and will accumulate in the fractures (almost none will get into the matrix). Design optimization will be needed to ensure adequate spatial distribution of the CO2 and sufficient time for CO2 miscibility.

  2. Zeolitic Imidazolate Framework-8 Membrane for H2/CO2 Separation: Experimental and Modeling

    Science.gov (United States)

    Lai, L. S.; Yeong, Y. F.; Lau, K. K.; Azmi, M. S.; Chew, T. L.

    2018-03-01

    In this work, ZIF-8 membrane synthesized through solvent evaporation secondary seeded growth was tested for single gas permeation and binary gases separation of H2 and CO2. Subsequently, a modified mathematical modeling combining the effects of membrane and support layers was applied to represent the gas transport properties of ZIF-8 membrane. Results showed that, the membrane has exhibited H2/CO2 ideal selectivity of 5.83 and separation factor of 3.28 at 100 kPa and 303 K. Besides, the experimental results were fitted well with the simulated results by demonstrating means absolute error (MAE) values ranged from 1.13 % to 3.88 % for single gas permeation and 10.81 % to 21.22 % for binary gases separation. Based on the simulated data, most of the H2 and CO2 gas molecules have transported through the molecular pores of membrane layer, which was up to 70 %. Thus, the gas transport of the gases is mainly dominated by adsorption and diffusion across the membrane.

  3. Los Angeles megacity: a high-resolution land–atmosphere modelling system for urban CO2 emissions

    Directory of Open Access Journals (Sweden)

    S. Feng

    2016-07-01

    Full Text Available Megacities are major sources of anthropogenic fossil fuel CO2 (FFCO2 emissions. The spatial extents of these large urban systems cover areas of 10 000 km2 or more with complex topography and changing landscapes. We present a high-resolution land–atmosphere modelling system for urban CO2 emissions over the Los Angeles (LA megacity area. The Weather Research and Forecasting (WRF-Chem model was coupled to a very high-resolution FFCO2 emission product, Hestia-LA, to simulate atmospheric CO2 concentrations across the LA megacity at spatial resolutions as fine as  ∼  1 km. We evaluated multiple WRF configurations, selecting one that minimized errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May–June 2010. Our results show no significant difference between moderate-resolution (4 km and high-resolution (1.3 km simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution and Hestia-LA (1.3 km resolution fossil fuel CO2 emission products to evaluate the impact of the spatial resolution of the CO2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO2 concentrations. We find that high spatial resolution in the fossil fuel CO2 emissions is more important than in the atmospheric model to capture CO2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO2 fields reflect the coverage of

  4. Analytical model for screening potential CO2 repositories

    Science.gov (United States)

    Okwen, R.T.; Stewart, M.T.; Cunningham, J.A.

    2011-01-01

    Assessing potential repositories for geologic sequestration of carbon dioxide using numerical models can be complicated, costly, and time-consuming, especially when faced with the challenge of selecting a repository from a multitude of potential repositories. This paper presents a set of simple analytical equations (model), based on the work of previous researchers, that could be used to evaluate the suitability of candidate repositories for subsurface sequestration of carbon dioxide. We considered the injection of carbon dioxide at a constant rate into a confined saline aquifer via a fully perforated vertical injection well. The validity of the analytical model was assessed via comparison with the TOUGH2 numerical model. The metrics used in comparing the two models include (1) spatial variations in formation pressure and (2) vertically integrated brine saturation profile. The analytical model and TOUGH2 show excellent agreement in their results when similar input conditions and assumptions are applied in both. The analytical model neglects capillary pressure and the pressure dependence of fluid properties. However, simulations in TOUGH2 indicate that little error is introduced by these simplifications. Sensitivity studies indicate that the agreement between the analytical model and TOUGH2 depends strongly on (1) the residual brine saturation, (2) the difference in density between carbon dioxide and resident brine (buoyancy), and (3) the relationship between relative permeability and brine saturation. The results achieved suggest that the analytical model is valid when the relationship between relative permeability and brine saturation is linear or quasi-linear and when the irreducible saturation of brine is zero or very small. ?? 2011 Springer Science+Business Media B.V.

  5. Regional-scale brine migration along vertical pathways due to CO2 injection - Part 1: The participatory modeling approach

    Science.gov (United States)

    Scheer, Dirk; Konrad, Wilfried; Class, Holger; Kissinger, Alexander; Knopf, Stefan; Noack, Vera

    2017-06-01

    Saltwater intrusion into potential drinking water aquifers due to the injection of CO2 into deep saline aquifers is one of the potential hazards associated with the geological storage of CO2. Thus, in a site selection process, models for predicting the fate of the displaced brine are required, for example, for a risk assessment or the optimization of pressure management concepts. From the very beginning, this research on brine migration aimed at involving expert and stakeholder knowledge and assessment in simulating the impacts of injecting CO2 into deep saline aquifers by means of a participatory modeling process. The involvement exercise made use of two approaches. First, guideline-based interviews were carried out, aiming at eliciting expert and stakeholder knowledge and assessments of geological structures and mechanisms affecting CO2-induced brine migration. Second, a stakeholder workshop including the World Café format yielded evaluations and judgments of the numerical modeling approach, scenario selection, and preliminary simulation results. The participatory modeling approach gained several results covering brine migration in general, the geological model sketch, scenario development, and the review of the preliminary simulation results. These results were included in revised versions of both the geological model and the numerical model, helping to improve the analysis of regional-scale brine migration along vertical pathways due to CO2 injection.

  6. Regional-scale brine migration along vertical pathways due to CO2 injection – Part 1: The participatory modeling approach

    Directory of Open Access Journals (Sweden)

    D. Scheer

    2017-06-01

    Full Text Available Saltwater intrusion into potential drinking water aquifers due to the injection of CO2 into deep saline aquifers is one of the potential hazards associated with the geological storage of CO2. Thus, in a site selection process, models for predicting the fate of the displaced brine are required, for example, for a risk assessment or the optimization of pressure management concepts. From the very beginning, this research on brine migration aimed at involving expert and stakeholder knowledge and assessment in simulating the impacts of injecting CO2 into deep saline aquifers by means of a participatory modeling process. The involvement exercise made use of two approaches. First, guideline-based interviews were carried out, aiming at eliciting expert and stakeholder knowledge and assessments of geological structures and mechanisms affecting CO2-induced brine migration. Second, a stakeholder workshop including the World Café format yielded evaluations and judgments of the numerical modeling approach, scenario selection, and preliminary simulation results. The participatory modeling approach gained several results covering brine migration in general, the geological model sketch, scenario development, and the review of the preliminary simulation results. These results were included in revised versions of both the geological model and the numerical model, helping to improve the analysis of regional-scale brine migration along vertical pathways due to CO2 injection.

  7. Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases.

    Science.gov (United States)

    Mohanty, C R; Meikap, B C

    2011-03-15

    A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO(2)) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO(2) was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO(2) was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO(2) concentration. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases

    International Nuclear Information System (INIS)

    Mohanty, C.R.; Meikap, B.C.

    2011-01-01

    A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO 2 ) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO 2 was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO 2 was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO 2 concentration.

  9. Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage

    KAUST Repository

    Allen, Rebecca

    2015-04-01

    ABSTRACT Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage Rebecca Allen Geological CO2 storage is an engineering feat that has been undertaken around the world for more than two decades, thus accurate modeling of flow and transport behavior is of practical importance. Diffusive and convective transport are relevant processes for buoyancy-driven convection of CO2 into underlying fluid, a scenario that has received the attention of numerous modeling studies. While most studies focus on Darcy-scale modeling of this scenario, relatively little work exists at the pore-scale. In this work, properties evaluated at the pore-scale are used to investigate the transport behavior modeled at the Darcy-scale. We compute permeability and two different forms of tortuosity, namely hydraulic and diffusive. By generating various pore ge- ometries, we find hydraulic and diffusive tortuosity can be quantitatively different in the same pore geometry by up to a factor of ten. As such, we emphasize that these tortuosities should not be used interchangeably. We find pore geometries that are characterized by anisotropic permeability can also exhibit anisotropic diffusive tortuosity. This finding has important implications for buoyancy-driven convection modeling; when representing the geological formation with an anisotropic permeabil- ity, it is more realistic to also account for an anisotropic diffusivity. By implementing a non-dimensional model that includes both a vertically and horizontally orientated 5 Rayleigh number, we interpret our findings according to the combined effect of the anisotropy from permeability and diffusive tortuosity. In particular, we observe the Rayleigh ratio may either dampen or enhance the diffusing front, and our simulation data is used to express the time of convective onset as a function of the Rayleigh ratio. Also, we implement a lattice Boltzmann model for thermal convective flows, which we treat as an analog for

  10. Evaluation of simplified analytical models for CO2 plume movement and pressure buildup

    Science.gov (United States)

    Oruganti, Y.; Mishra, S.

    2011-12-01

    CO2 injection into the sub-surface is emerging as a viable technology for reducing anthropogenic CO2 emissions into the atmosphere. When large amounts of CO2 are sequestered, pressure buildup is an associated risk, along with plume movement beyond the injected domain. In this context, simple modeling tools become valuable assets in preliminary CO2 injection project screening and implementation phases. This study presents an evaluation of two commonly used simplified analytical models for plume movement and pressure buildup, (1) the sharp interface model of Nordbotten et al. (2005), and the corresponding pressure distribution solution of Mathias et al. (2008), and (2) the 3-region model of Burton et al. (2008) based on fractional flow and steady-state pressure gradient considerations. The three-region model of Burton et al. assumes a constant pressure outer boundary. In this study, we incorporate the radius of investigation of the pressure front as the transient pressure boundary, in order to represent an infinite-acting system. The sharp-interface model also assumes the system to be infinite-acting. Temperature and pressure conditions used in these models correspond to the "warm, shallow" and "cold, deep" aquifer conditions as defined by Nordbotten et al. The saturation and pressure profiles as well as injection-well pressure buildup predicted by the analytical models are compared with those from the numerical simulator STOMP in order to provide a verification of the simplified modeling assumptions. Both the STOMP results and the three-region model show two sharp fronts (the drying and two-phase fronts), and a good match is obtained between the front positions at any time. For the sharp interface model, the vertically averaged gas saturation does not exhibit two sharp fronts as seen in the STOMP simulations, but shows a gradual change in saturation with radial distance over the two-phase region. The pressure profiles from STOMP and the analytical model are

  11. Modelling of electricity generation of large interconnected power systems: How can a CO2 tax influence the European generation mix

    International Nuclear Information System (INIS)

    Voorspools, Kris R.; D'haeseleer, William D.

    2006-01-01

    This paper discusses a methodology for detailed modelling of electricity generation of large interconnected power systems in a liberalised market. The resulting model, called E-Simulate, respects the technological restrictions and boundary conditions inherent to power generation and simulates the power generation and cross border trade on an hourly basis and on a power plant level. Nevertheless, E-Simulate is sufficiently flexible, transparent and fast. It is a valid, objective and useful tool in the simulation of the impact of power generation topics in the context of liberalised markets and GHG emission reduction. As a comprehensive example of the use and the strength of E-Simulate, we study the effect of a CO 2 tax on power generation and electricity trade in and between eight interconnected European zones: The Netherlands, Belgium/Luxemburg, France, Germany, Spain, Portugal, Switzerland and Italy. A CO 2 tax of 10 Euro /ton CO 2 causes an overall CO 2 emission reduction of about 6%. We notice an overall increase in gas fired generation and a corresponding reduction of coal and lignite fired generation on a trans-national level. In some zones (The Netherlands, Belgium/Luxemburg and Italy), the emissions will rise. In others (France, Germany and Spain), emissions will decrease. This is a result of the CO 2 tax that not only causes a shift towards fuels with lower carbon content but also, and correspondingly, leads to a redistribution of cross border trade

  12. Simulation of CO2 concentrations at Tsukuba tall tower using WRF ...

    Indian Academy of Sciences (India)

    using WRF-CO2 tracer transport model. Srabanti Ballav1,4,∗, Prabir K Patra2, Yousuke Sawa3, Hidekazu Matsueda3,. Ahoro Adachi3, Shigeru Onogi3, Masayuki Takigawa2 and Utpal K De1. 1School of Environmental Studies, Jadavpur University, Kolkata 700 032, India. 2Department of Environmental Geochemical Cycle ...

  13. Global Monthly CO2 Flux Inversion Based on Results of Terrestrial Ecosystem Modeling

    NARCIS (Netherlands)

    Deng, F.; Chen, J.; Peters, W.; Krol, M.

    2008-01-01

    Most of our understanding of the sources and sinks of atmospheric CO2 has come from inverse studies of atmospheric CO2 concentration measurements. However, the number of currently available observation stations and our ability to simulate the diurnal planetary boundary layer evolution over

  14. Fluid Flow Simulation For CO2-EOR and Sequestration Utilizing Geomechanical Constraints - Teapot Dome Oil Field, Wyoming

    Science.gov (United States)

    Chiaramonte, L.; Zoback, M. D.; Friedmann, J.; Stamp, V.

    2007-12-01

    Mature oil and gas reservoirs are attractive targets for geological sequestration of CO2 because of their potential storage capacities and the possible cost offsets from enhanced oil recovery (EOR). In this work we develop a 3D reservoir model and fluid flow simulation of the Tensleep Formation using geomechanical constraints to evaluate the feasibility of a CO2-EOR injection project at Teapot Dome Oil Field, WY. The objective of this work is to model the migration of the injected CO2 as well as to obtain limits on the rates and volumes of CO2 that can be injected without compromising seal integrity. Teapot Dome is an elongated asymmetrical, basement-cored anticline with a north-northwest axis. It is part of the Salt Creek structural trend, located in the southwestern edge of the Powder River Basin. The Tensleep Fm. in this area consists of interdune deposits such as eolian sandstones, sabkha carbonates, evaporites (mostly anhydrite), and some very low permeability dolomicrites. The average porosity is 0.10 ranging from 0.05-0.20. The average permeability is 30 mD, ranging from 10 - 100 mD. The average reservoir thickness is 50 ft. The reservoir has strong aquifer drive. In the area under study, the Tensleep Fm. has its structural crest at 1675 m. It presents a 3-way closure trap against a NE-SW fault to the north. We previously carried out a geomechanical stability analysis and found this fault to be able to support the increase in pressure due to the CO2 to be injected, even if the structure was "filled-to-spill". In this work we combine our previous geomechanical analysis, geostatistical reservoir modeling and fluid flow simulations to investigate critical questions regarding the feasibility of a CO2-EOR project in the Tensleep Fm. The analysis takes into consideration the initial trapping and sealing mechanisms of the reservoir, the consequences of past and present oil production on the initial properties, and the potential effect of CO2 injection on both the

  15. Simulated carbon sink response of shortgrass steppe, tallgrass prairie and forest ecosystems to rising [CO2], temperature and nitrogen input

    Science.gov (United States)

    Pepper, D. A.; Del Grosso, S. J.; McMurtrie, R. E.; Parton, W. J.

    2005-03-01

    The response of plant ecosystems to environmental change will determine whether the terrestrial biosphere will remain a substantial carbon sink or become a source during the next century. We use two ecosystem models, the Generic Decomposition And Yield model (G'DAY) and the daily time step version of the Century model (DAYCENT), to simulate net ecosystem productivity (NEP) for three contrasting ecosystems (shortgrass steppe in Colorado, tallgrass prairie in Kansas, and Norway spruce in Sweden) with varying degrees of water, temperature, and nutrient limitation, to determine responses to gradual increases in atmospheric CO2 concentration ([CO2]), temperature, and nitrogen input over 100 years. Using G'DAY, under rising [CO2], there is evidence of C sink "saturation," defined here as positive NEP reaching an upper limit and then declining toward zero, at all three sites (due largely to increased N immobilization in soil organic matter) but a positive C sink is sustained throughout the 100 years. DAYCENT also predicts a sustained C sink at all three sites under rising [CO2], with evidence of C sink saturation for the Colorado grassland and the C sink levels off after 80 years for the Kansas grassland. Warming reduces soil C and the C sink in both grassland ecosystems but increases the C sink in the forest. Warming increases decomposition and soil N mineralization, which stimulates net primary productivity (NPP) at all sites except when inducing water limitation. At the forest site some of the enhanced N release is allocated to a woody biomass pool with a low N:C ratio so that warming enhances NEP without increased N input at the forest site, but not at the grassland sites. Responses to combinations of treatments are generally additive for DAYCENT but more interactive for G'DAY, especially under combined rising [CO2] and warming at the strongly water- and N-limited shortgrass steppe. Increasing N input alleviates C sink saturation and enhances NEP, NPP, and soil C at

  16. Multi-model comparison of CO2 emissions peaking in China: Lessons from CEMF01 study

    Directory of Open Access Journals (Sweden)

    Oleg Lugovoy

    2018-03-01

    Full Text Available The paper summarizes results of the China Energy Modeling Forum's (CEMF first study. Carbon emissions peaking scenarios, consistent with China's Paris commitment, have been simulated with seven national and industry-level energy models and compared. The CO2 emission trends in the considered scenarios peak from 2015 to 2030 at the level of 9–11 Gt. Sector-level analysis suggests that total emissions pathways before 2030 will be determined mainly by dynamics of emissions in the electric power industry and transportation sector. Both sectors will experience significant increase in demand, but have low-carbon alternative options for development. Based on a side-by-side comparison of modeling input and results, conclusions have been drawn regarding the sources of emissions projections differences, which include data, views on economic perspectives, or models' structure and theoretical framework. Some suggestions have been made regarding energy models' development priorities for further research. Keywords: Carbon emissions projections, Climate change, CO2 emissions peak, China's Paris commitment, Top-Down energy models, Bottom-Up energy models, Multi model comparative study, China Energy Modeling Forum (CEMF

  17. Comparison of TCCON and GOSAT Column Averaged CO2 to Global Atmospheric Transport Modeling

    Science.gov (United States)

    Liu, Y.; Kawa, S. R.; Collatz, G. J.; Wang, J. S.

    2012-12-01

    The measurements of column averaged CO2 contain ground surface CO2 flux signals. Comparing these observations to modeling results helps us to better understand the distributions and variations of CO2 sources and sinks and to evaluate the model transport. In this study, we ran a global atmospheric transport model (PCTM) from 2003 to 2011, using a near-balanced bottom up CASA/GSFC-GFED2 CO2 emissions and uptake as the biospheric part of total CO2 flux. All the transport modeling and biospheric CO2 fluxes are forced or driven by NASA MERRA reanalysis data. The PCTM model captures the observed CO2 seasonal cycles and inter-hemispheric gradients at TCCON sites well, within about a ppmv in most instances. The model also agrees very well with observations in the phase and amplitude of synoptic variations, showing high spatial and temporal correlations. These results suggest that the PCTM model has a good skill in capturing variable processes at different atmospheric levels, including the surface level CO2 signals. This study also shows that the CO2 fluxes used in the modeling (primarily the biospheric ones) provide a reasonably good prior representation of the CO2 flux distribution globally. Comparison analysis of GOSAT XCO2 data to PCTM modeling is mainly done on the monthly basis. The GOSAT XCO2 data used are from the JPL ACOS team's version 2.9. We co-sampled the modeling results with GOSAT XCO2 measurements spatially and temporally. Results show the GOSAT retrievals have the ability to capture the seasonal cycles globally, generally presenting reasonable positive correlations with modeling, with some persistent negative biases. On the synoptic scale, GOSAT XCO2 shows obvious discrepancies with modeling in some areas, suggesting possible large uncertainties in the XCO2 retrievals. We also compared the column CO2 data to output from a perturbed CO2 flux model to test the sensitivity of the observations in detecting small flux changes. These sensitivity experiments will

  18. Lattice Boltzmann simulation of dissolution-induced changes in permeability and porosity in 3D CO2 reactive transport

    Science.gov (United States)

    Tian, Zhiwei; Wang, Junye

    2018-02-01

    Dissolution and precipitation of rock matrix are one of the most important processes of geological CO2 sequestration in reservoirs. They change connections of pore channels and properties of matrix, such as bulk density, microporosity and hydraulic conductivity. This study builds on a recently developed multi-layer model to account for dynamic changes of microporous matrix that can accurately predict variations in hydraulic properties and reaction rates due to dynamic changes in matrix porosity and pore connectivity. We apply the model to simulate the dissolution and precipitation processes of rock matrix in heterogeneous porous media to quantify (1) the effect of the reaction rate on dissolution and matrix porosity, (2) the effect of microporous matrix diffusion on the overall effective diffusion and (3) the effect of heterogeneity on hydraulic conductivity. The results show the CO2 storage influenced by factors including the matrix porosity change, reaction front movement, velocity and initial properties. We also simulated dissolution-induced permeability enhancement as well as effects of initial porosity heterogeneity. The matrix with very low permeability, which can be unresolved on X-ray CT, do contribute to flow patterns and dispersion. The concentration of reactant H+ increases along the main fracture paths where the flow velocity increases. The product Ca++ shows the inversed distribution pattern against the H+ concentration. This demonstrates the capability of this model to investigate the complex CO2 reactive transport in real 3D heterogeneous porous media.

  19. Modeling permeation of CO2/CH4, N2/CH4, and CO2/air mixtures across a DD3R zeolite membrane

    NARCIS (Netherlands)

    van den Bergh, J.; Mittelmeijer-Hazeleger, M.; Kapteijn, F.

    2010-01-01

    Single component (CO2, CH4, and N2) and equimolar binary mixture (CO2/CH4, N2/CH4, and CO2/Air) permeation data across a disk-shaped all-silica DDR zeolite membrane have been the subject of a thorough modeling study over a challenging broad temperature (220−373 K) and feed pressure (101−1500 kPa)

  20. CO2FIX V 3.1 A modelling framework for quantifying carbon sequestration in forest ecosystems

    NARCIS (Netherlands)

    Schelhaas, M.J.; Esch, van P.W.; Groen, T.A.; Jong, de B.H.J.; Kanninen, M.; Liski, J.; Masera, O.; Mohren, G.M.J.; Nabuurs, G.J.; Palosuo, T.; Pedroni, L.; Vallejo, A.; Vilén, T.

    2004-01-01

    This report describes the conceptual approach of the CO2FIX V 3.1 model, as well as its implementation and numerous examples. This stand level simulation model is a tool which quantifies the C stocks and fluxes in the forest biomass, the soil organic matter and the wood products chain. Included are

  1. Preliminary Study of S-CO2 cycle simulation using MARS

    International Nuclear Information System (INIS)

    Cho, Jay; Lee, Jeong Ik

    2014-01-01

    The supercritical carbon dioxide Brayton cycle has become a strong candidate for use in the next generation nuclear reactors. To test the cycle under many different conditions an apparatus named SCO 2 PE has been built in KAIST. The experimental data is to be compared with simulation results from a code named MARS. The pipelines, globe valve, heat exchanger, and pump have been nodalized as written above. Using the work done so far, we will be able to simulate the experiment as soon as the right version of MARS arrives. Once we have the simulation results, we may improve the simulation result by adding more realistic features to the input and study the missing gap for the accurate simulation of S-CO 2 system

  2. Estimation of CO2 Transport Costs in South Korea Using a Techno-Economic Model

    Directory of Open Access Journals (Sweden)

    Kwangu Kang

    2015-03-01

    Full Text Available In this study, a techno–economic model was used to calculate the costs of CO2 transport and specify the major equipment required for transport in order to demonstrate and implement CO2 sequestration in the offshore sediments of South Korea. First, three different carbon capture and storage demonstration scenarios were set up involving the use of three CO2 capture plants and one offshore storage site. Each transport scenario considered both the pipeline transport and ship transport options. The temperature and pressure conditions of CO2 in each transport stage were determined from engineering and economic viewpoints, and the corresponding specifications and equipment costs were calculated. The transport costs for a 1 MtCO2/year transport rate were estimated to be US$33/tCO2 and US$28/tCO2 for a pipeline transport of ~530 km and ship transport of ~724 km, respectively. Through the economies of scale effect, the pipeline and ship transport costs for a transport rate of 3 MtCO2/year were reduced to approximately US$21/tCO2 and US$23/tCO2, respectively. A CO2 hub terminal did not significantly reduce the cost because of the short distance from the hub to the storage site and the small number of captured sources.

  3. Consistent phase-change modeling for CO2-based heat mining operation

    DEFF Research Database (Denmark)

    Singh, Ashok Kumar; Veje, Christian

    2017-01-01

    –gas phase transition with more accuracy and consistency. Calculation of fluid properties and saturation state were based on the volume translated Peng–Robinson equation of state and results verified. The present model has been applied to a scenario to simulate a CO2-based heat mining process. In this paper......The accuracy of mathematical modeling of phase-change phenomena is limited if a simple, less accurate equation of state completes the governing partial differential equation. However, fluid properties (such as density, dynamic viscosity and compressibility) and saturation state are calculated using...... a highly accurate, complex equation of state. This leads to unstable and inaccurate simulation as the equation of state and governing partial differential equations are mutually inconsistent. In this study, the volume-translated Peng–Robinson equation of state was used with emphasis to model the liquid...

  4. Reservoir Characterization and Flow Simulation for CO 2-EOR in the Tensleep Formation Using Discrete Fracture Networks, Teapot Dome, Wyoming

    Science.gov (United States)

    Kavousi Ghahfarokhi, Payam

    results to build an 8 component equation of the state. A fully compositional flow simulation is conducted to acquire a history match between model production and production history. The history matching process reveals that high fracture permeabilities enhance water conning around the producers and decreases the oil production. Moreover, increasing apertures in the model DFN will result in higher oil production from the field. Thus, aperture and vertical permeabilities are adjusted for the model DFN to approximate the production history. We analyzed two CO2-EOR cases with different injection patterns. One has the injectors parallel to the main fracture set and the second one has injectors perpendicular to the main fracture set. Results show that the former model has higher oil recovery with later CO2 breakthrough than the second model. The dominant fracture set (N76°W) affects the CO2-EOR sweep efficiency in the Tensleep reservoir. We show that CO2 breakthrough is inevitable in both cases. The fault transmissibility multipliers are also assumed; they are uncertain parameters that could influence CO2-EOR. The model with completely impermeable faults yields a lower CO2-EOR sweep efficiency compared to the case for which all faults are fully permeable.

  5. Evidence from mathematical modeling that carbonic anhydrase II and IV enhance CO2 fluxes across Xenopus oocyte plasma membranes.

    Science.gov (United States)

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

    2014-11-01

    Exposing an oocyte to CO2/HCO3 (-) causes intracellular pH (pHi) to decline and extracellular-surface pH (pHS) to rise to a peak and decay. The two companion papers showed that oocytes injected with cytosolic carbonic anhydrase II (CA II) or expressing surface CA IV exhibit increased maximal rate of pHi change (dpHi/dt)max, increased maximal pHS changes (ΔpHS), and decreased time constants for pHi decline and pHS decay. Here we investigate these results using refinements of an earlier mathematical model of CO2 influx into a spherical cell. Refinements include 1) reduced cytosolic water content, 2) reduced cytosolic diffusion constants, 3) refined CA II activity, 4) layer of intracellular vesicles, 5) reduced membrane CO2 permeability, 6) microvilli, 7) refined CA IV activity, 8) a vitelline membrane, and 9) a new simulation protocol for delivering and removing the bulk extracellular CO2/HCO3 (-) solution. We show how these features affect the simulated pHi and pHS transients and use the refined model with the experimental data for 1.5% CO2/10 mM HCO3 (-) (pHo = 7.5) to find parameter values that approximate ΔpHS, the time to peak pHS, the time delay to the start of the pHi change, (dpHi/dt)max, and the change in steady-state pHi. We validate the revised model against data collected as we vary levels of CO2/HCO3 (-) or of extracellular HEPES buffer. The model confirms the hypothesis that CA II and CA IV enhance transmembrane CO2 fluxes by maximizing CO2 gradients across the plasma membrane, and it predicts that the pH effects of simultaneously implementing intracellular and extracellular-surface CA are supra-additive. Copyright © 2014 the American Physiological Society.

  6. CO2 taxes, double dividend and competition in the energy sector: Applications of the Danish CGE model ECOSMEC

    International Nuclear Information System (INIS)

    Goertz, M.; Hansen, J.V.; Larsen, M.

    1999-01-01

    In this paper we develop a new CGE model of the Danish economy with the acronym ECOSMEC (Economic COuncil Simulation Model with Energy markets and Carbon taxation). The model is a hybrid of two existing static models developed by respectively the Secretariat of the Danish Economic Council and by the MobiDK model project in the Ministry of Business and Industry. Distinct features of the ECOSMEC models are a rather disaggregated modelling of energy demand and supply, introduction of various market structures in the energy sector, and a consistent specification of different household types. The simulations presented in the paper have the following implications: Firstly, a uniform CO 2 tax of approximately 300 DKK per ton could reduce emissions by 20 per cent in a scenario with perfect competition in the energy sector. Secondly, a double dividend (reduced emissions and increased welfare) could be gained by using the CO 2 tax revenue for reducing distorting income taxes. However, the double dividend result depends decisively on the applied elasticity of substitution between consumption and leisure. Thirdly, assuming different market structures in the energy sector influences the uniform CO 2 tax needed to reach a given emission target. Fourthly, the empirical aguments for differentiated CO 2 taxes motivated by imperfect energy markets are weak. Fifthly, the Danish economy could benefit from a deregulation of the electricity and district heating sector with respect to welfare and economic activity. This result holds also if CO 2 emissions are kept constant. (au)

  7. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)

    2016-11-11

    Nov 11, 2016 ... Theoretical modelling; diffusion-cooled CW CO2 laser; rate equation model; simultaneous linear equations; matrix solution. PACS Nos 42.55. ... In this paper, we extend the application of this model to a CW CO2 laser. However, we should ... mines the output power. Our results agree with the experimentally ...

  8. Application of free-air CO2 enrichment (FACE) technology to a forest canopy: A simulation study

    International Nuclear Information System (INIS)

    Lipfert, F.W.; Hendrey, G.R.; Lewin, K.L.; Alexander, Y.

    1992-03-01

    Forest ecosystems constitute an important part of the planet's land cover. Understanding their exchanges of carbon with the atmosphere is crucial in projecting future net atmospheric CO 2 increases. It is also important that experimental studies of these processes be performed under conditions which are as realistic as possible, particularly with respect to photosynthesis and evapotranspiration. New technology and experimental protocols now exist which can facilitate studying an undisturbed forest canopy under long-term enriched CO 2 conditions. The International Geosphere Biosphere Program of the International Council of Scientific Unions has established a subprogram on Global Change and Terrestrial Ecosystems (GCTE). This program is driven by two major concerns: to be able to predict the effects of global change on the structure and function of ecosystems, and to predict how these changes will control both atmospheric CO 2 and climate, through various feedback pathways. Brookhaven National Laboratory (BNL) has developed a system for exposing field-grown plants to controlled elevated concentrations of atmospheric gases, without use of confining chambers that alter important atmospheric exchange processes. This system, called FACE for Free Air CO 2 Enrichment. This paper focuses on the fluid mechanics of free-air fumigation and uses a numerical simulation model based on superposed gaussian plumes to project how the present ground-based system could be used to fumigate an elevated forest canopy

  9. Experimental and simulation studies of iron oxides for geochemical fixation of CO2-SO2 gas mixtures

    Science.gov (United States)

    Garcia, Susana; Rosenbauer, Robert J.; Palandri, James; Maroto-Valer, M. Mercedes

    2011-01-01

    Iron-bearing minerals are reactive phases of the subsurface environment and could potentially trap CO2–SO2gas mixtures derived from fossil fuel combustion processes by their conversion to siderite (FeCO3) and dissolved sulfate. Changes in fluid and mineral compositions resulting from reactions, involving the co-injection of SO2 with CO2 were observed both theoretically and experimentally. Experiments were conducted with a natural hematite (α-Fe2O3) sample. A high pressure-high temperature apparatus was used to simulate conditions in geologic formations deeper than 800 m, where CO2 is in the supercritical state. Solid samples were allowed to react with a NaCl–NaOH brine and SO2-bearing CO2-dominated gas mixtures. The predicted equilibrium mineral assemblage at 100 °C and 250 bar became hematite, dawsonite (NaAl(OH)2CO3), siderite (FeCO3) and quartz (SiO2). Experimentally, siderite and dawsonite, derived from the presence of kaolinite (Al2Si2O5(OH)4) in the parent material, were present in residual solids at longer reaction time intervals, which agreed well with results from the modelling work.

  10. Changes in the Arctic Ocean CO2 sink (1996-2007): A regional model analysis

    Science.gov (United States)

    Manizza, M.; Follows, M. J.; Dutkiewicz, S.; Menemenlis, D.; Hill, C. N.; Key, R. M.

    2013-12-01

    The rapid recent decline of Arctic Ocean sea ice area increases the flux of solar radiation available for primary production and the area of open water for air-sea gas exchange. We use a regional physical-biogeochemical model of the Arctic Ocean, forced by the National Centers for Environmental Prediction/National Center for Atmospheric Research atmospheric reanalysis, to evaluate the mean present-day CO2 sink and its temporal evolution. During the 1996-2007 period, the model suggests that the Arctic average sea surface temperature warmed by 0.04°C a-1, that sea ice area decreased by ˜0.1 × 106 km2 a-1, and that the biological drawdown of dissolved inorganic carbon increased. The simulated 1996-2007 time-mean Arctic Ocean CO2 sink is 58 ± 6 Tg C a-1. The increase in ice-free ocean area and consequent carbon drawdown during this period enhances the CO2 sink by ˜1.4 Tg C a-1, consistent with estimates based on extrapolations of sparse data. A regional analysis suggests that during the 1996-2007 period, the shelf regions of the Laptev, East Siberian, Chukchi, and Beaufort Seas experienced an increase in the efficiency of their biological pump due to decreased sea ice area, especially during the 2004-2007 period, consistent with independently published estimates of primary production. In contrast, the CO2 sink in the Barents Sea is reduced during the 2004-2007 period due to a dominant control by warming and decreasing solubility. Thus, the effect of decreasing sea ice area and increasing sea surface temperature partially cancel, though the former is dominant.

  11. Modelling the Response of Energy, Water and CO2 Fluxes Over Forests to Climate Variability

    Science.gov (United States)

    Ju, W.; Chen, J.; Liu, J.; Chen, B.

    2004-05-01

    Understanding the response of energy, water and CO2 fluxes of terrestrial ecosystems to climate variability at various temporal scales is of interest to climate change research. To simulate carbon (C) and water dynamics and their interactions at the continental scale with high temporal and spatial resolutions, the remote sensing driven BEPS (Boreal Ecosystem Productivity Simulator) model was updated to couple with the soil model of CENTURY and a newly developed biophysical model. This coupled model separates the whole canopy into two layers. For the top layer, the leaf-level conductance is scaled up to canopy level using a sunlit and shaded leaf separation approach. Fluxes of water, and CO{2} are simulated as the sums of those from sunlit and shaded leaves separately. This new approach allows for close coupling in modeling these fluxes. The whole profile of soil under a seasonal snowpack is split into four layers for estimating soil moisture and temperature. Long-term means of the vegetation productivity and climate are employed to initialize the carbon pools for the computation of heterotrophic respiration. Validated against tower data at four forested sites, this model is able to describe these fluxes and their response to climate variability. The model captures over 55% of year-round half/one hourly variances of these fluxes. The highest agreement of model results with tower data was achieved for CO2 flux at Southern Old Aspen (SOA) (R2>0.85 and RMSE<2.37 μ mol C m-2 s-1, N=17520). However, the model slightly overestimates the diurnal amplitude of sensible heat flux in winter and sometimes underestimates that of CO2 flux in the growing season. Model simulations suggest that C uptakes of forests are controlled by climate variability and the response of C cycle to climate depends on forest type. For SOA, the annual NPP (Net Primary Productivity) is more sensitive to temperature than to precipitation. This forest usually has higher NPP in warm years than in cool

  12. Molecular dynamics simulations of polyethers and a quaternary ammonium ionic liquid as CO2 absorbers

    Science.gov (United States)

    Cardoso, Piercarlo Fortunato; Fernandez, Juan S. L. C.; Lepre, Luiz Fernando; Ando, Rômulo Augusto; Costa Gomes, Margarida F.; Siqueira, Leonardo J. A.

    2018-04-01

    The properties of mixtures of butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N4111][NTf2], with poly(ethyleneglycol) dimethyl ether, PEO, were described as a function of PEO chain size by molecular dynamics simulations. Both PEO chain size and mixture composition revealed to play a significant role in determining the structure and the dynamics of the fluids. The remarkably higher viscosity observed for mixtures composed by 0.25 mole fraction of PEO was attributed to the increase in the gauche population of OCCO dihedral of the polyether of longer chains. The negative solvation enthalpy (ΔsolH the neat and mixture systems. The CO2 absorption was higher in neat PEO, particularly considering longer chains. The gas solubility in the mixtures presented intermediate values in comparison to the neat PEO and neat ionic liquid. The CO2 solutions had their structures discussed in the light of the calculated radial and spatial distribution functions.

  13. CARVE: Monthly Atmospheric CO2 Concentrations (2009-2013) and Modeled Fluxes, Alaska

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports monthly averages of atmospheric CO2 concentration from satellite and airborne observations between 2009 and 2013 and simulated present and...

  14. Accounting for geochemical alterations of caprock fracture permeability in basin-scale models of leakage from geologic CO2 reservoirs

    Science.gov (United States)

    Guo, B.; Fitts, J. P.; Dobossy, M.; Bielicki, J. M.; Peters, C. A.

    2012-12-01

    Climate mitigation, public acceptance and energy, markets demand that the potential CO2 leakage rates from geologic storage reservoirs are predicted to be low and are known to a high level of certainty. Current approaches to predict CO2 leakage rates assume constant permeability of leakage pathways (e.g., wellbores, faults, fractures). A reactive transport model was developed to account for geochemical alterations that result in permeability evolution of leakage pathways. The one-dimensional reactive transport model was coupled with the basin-scale Estimating Leakage Semi-Analytical (ELSA) model to simulate CO2 and brine leakage through vertical caprock pathways for different CO2 storage reservoir sites and injection scenarios within the Mt. Simon and St. Peter sandstone formations of the Michigan basin. Mineral dissolution in the numerical reactive transport model expands leakage pathways and increases permeability as a result of calcite dissolution by reactions driven by CO2-acidified brine. A geochemical model compared kinetic and equilibrium treatments of calcite dissolution within each grid block for each time step. For a single fracture, we investigated the effect of the reactions on leakage by performing sensitivity analyses of fracture geometry, CO2 concentration, calcite abundance, initial permeability, and pressure gradient. Assuming that calcite dissolution reaches equilibrium at each time step produces unrealistic scenarios of buffering and permeability evolution within fractures. Therefore, the reactive transport model with a kinetic treatment of calcite dissolution was coupled to the ELSA model and used to compare brine and CO2 leakage rates at a variety of potential geologic storage sites within the Michigan basin. The results are used to construct maps based on the susceptibility to geochemically driven increases in leakage rates. These maps should provide useful and easily communicated inputs into decision-making processes for siting geologic CO2

  15. Simulation of a Potential CO2 Storage in the West Paris Basin: Site Characterization and Assessment of the Long-Term Hydrodynamical and Geochemical Impacts Induced by the CO2 Injection

    Directory of Open Access Journals (Sweden)

    Estublier Audrey

    2017-07-01

    Full Text Available This article presents the preliminary results of a study carried out as part of a demonstration project of CO2 storage in the Paris Basin. This project funded by ADEME (French Environment and Energy Management Agency and several industrial partners (TOTAL, ENGIE, EDF, Lafarge, Air Liquide, Vallourec aimed to study the possibility to set up an experimental infrastructure of CO2 transport and storage. Regarding the storage, the objectives were: (1 to characterize the selected site by optimizing the number of wells in a CO2 injection case of 200 Mt over 50 years in the Trias, (2 to simulate over time the CO2 migration and the induced pressure field, and (3 to analyze the geochemical behavior of the rock over the long term (1,000 years. The preliminary site characterization study revealed that only the southern area of Keuper succeeds to satisfy this injection criterion using only four injectors. However, a complementary study based on a refined fluid flow model with additional secondary faults concluded that this zone presents the highest potential of CO2 injection but without reaching the objective of 200 Mt with a reasonable number of wells. The simulation of the base scenario, carried out before the model refinement, showed that the overpressure above 0.1 MPa covers an area of 51,869 km2 in the Chaunoy formation, 1,000 years after the end of the injection, which corresponds to the whole West Paris Basin, whereas the CO2 plume extension remains small (524 km2. This overpressure causes brine flows at the domain boundaries and a local overpressure in the studied oil fields. Regarding the preliminary risk analysis of this project, the geochemical effects induced by the CO2 injection were studied by simulating the fluid-rock interactions with a coupled geochemical and fluid flow model in a domain limited to the storage complex. A one-way coupling of two models based on two domains fitting into each other was developed using dynamic boundary

  16. Thermodynamic modeling of CO2 absorption in aqueous N-Methyldiethanolamine using Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj

    2015-01-01

    A Thermodynamic model that can predict the behavior of the gas sweetening process over the applicable conditions is of vital importance in industry. In this work, Extended UNIQUAC model parameters optimized for the CO2-MDEA-H2O system are presented. Different types of experimental data consisting...... model accurately represents thermodynamic and thermal properties of the studied systems. The model parameters are valid in the temperature range from -15 to 200 °C, MDEA mass% of 5-75 and CO2 partial pressure of 0-6161.5 kPa....

  17. A fully-coupled flow-reactive-transport formulation based on element conservation, with application to CO2 storage simulations

    Science.gov (United States)

    Fan, Yaqing; Durlofsky, Louis J.; Tchelepi, Hamdi A.

    2012-06-01

    A numerical simulation framework for coupled multiphase flow, multicomponent transport and geochemical reactions in porous media is presented. The approach is an element-based formulation that combines the compositional modeling capabilities used in oil reservoir simulation with the treatment of chemical reactions used in groundwater modeling. The procedure employs a conservative finite-volume method with a fully-implicit treatment in time in order to preserve the nonlinear coupling of flow, transport, reactions, and mass transfer across phases. Phase behavior is described using cubic equations of state. In this framework, all the governing equations and associated constraints are cast in discrete residual form, such that any variable, or coefficient, can depend on any other variable in the problem. Prior to linearization, which is applied to construct the Jacobian matrix, no algebraic or analytic manipulation need be performed to reduce the nonlinear sets of equations and unknowns. Once the complete Jacobian matrix is assembled, a series of algebraic reductions (Schur complements), of the type used in compositional reservoir simulation, are performed to reduce the number of discrete equations that must be solved simultaneously. A GMRES solution strategy with CPR (Constrained Pressure Residual) preconditioning is applied to solve the reduced linear system. We demonstrate the formulation using two CO2 sequestration problems, one of which involves chemical reactions. The simulations demonstrate the efficiency and applicability of the overall procedure for modeling the long-term fate of sequestered CO2.

  18. A microscale model for combined CO2 diffusion and photosynthesis in leaves

    NARCIS (Netherlands)

    Ho, Q.T.; Verboven, P.; Yin, X.; Struik, P.C.; Nicolaï, B.M.

    2012-01-01

    Transport of CO2 in leaves was investigated by combining a 2-D, microscale CO2 transport model with photosynthesis kinetics in wheat (Triticum aestivum L.) leaves. The biophysical microscale model for gas exchange featured an accurate geometric representation of the actual 2-D leaf tissue

  19. Fluidized-Bed Heat Transfer Modeling for the Development of Particle/Supercritical-CO2 Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhiwen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Martinek, Janna G [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-06-03

    Concentrating solar power (CSP) technology is moving toward high-temperature and high-performance design. One technology approach is to explore high-temperature heat-transfer fluids and storage, integrated with a high-efficiency power cycle such as the supercritical carbon dioxide (s-CO2) Brayton power cycle. The s-CO2 Brayton power system has great potential to enable the future CSP system to achieve high solar-to-electricity conversion efficiency and to reduce the cost of power generation. Solid particles have been proposed as a possible high-temperature heat-transfer medium that is inexpensive and stable at high temperatures above 1,000 degrees C. The particle/heat exchanger provides a connection between the particles and s-CO2 fluid in the emerging s-CO2 power cycles in order to meet CSP power-cycle performance targets of 50% thermal-to-electric efficiency, and dry cooling at an ambient temperature of 40 degrees C. The development goals for a particle/s-CO2 heat exchanger are to heat s-CO2 to =720 degrees C and to use direct thermal storage with low-cost, stable solid particles. This paper presents heat-transfer modeling to inform the particle/s-CO2 heat-exchanger design and assess design tradeoffs. The heat-transfer process was modeled based on a particle/s-CO2 counterflow configuration. Empirical heat-transfer correlations for the fluidized bed and s-CO2 were used in calculating the heat-transfer area and optimizing the tube layout. A 2-D computational fluid-dynamics simulation was applied for particle distribution and fluidization characterization. The operating conditions were studied from the heat-transfer analysis, and cost was estimated from the sizing of the heat exchanger. The paper shows the path in achieving the cost and performance objectives for a heat-exchanger design.

  20. A Model for Interpreting High-Tower CO2 Concentration Records for the Surface Carbon Balance Information

    Science.gov (United States)

    Chen, B.; Chen, J. M.; Higuchi, K.; Chan, D.; Shashkov, A.

    2002-05-01

    Atmospheric CO2 concentration measurements have been made by scientists of Meteorological Service of Canada on a 40 m tower for the last 10 years at 15 minute intervals over a mostly intact boreal forest near Fraserdale (50N, 81W), Ontario, Canada. The long time records of CO2 as well as basic meteorological variables provide a unique opportunity to investigate any potential changes in the ecosystem in terms of carbon balance. A model is needed to decipher the carbon cycle signals from the diurnal and seasonal variation patterns in the CO2 record. For this purpose, the Boreal Ecosystem Productivity Simulator (BEPS) is expanded to include a one-dimensional CO2 vertical transfer model involving the interaction between plant canopies and the atmosphere in the surface layer and the diurnal dynamics of the mixed layer. An analytical solution of the scalar transfer equation within the surface layer is found using an assumption that the diurnal oscillation of CO2 concentration at a given height is sinusoidal, which is suitable for the investigation of the changes in diurnal variation pattern over the 10 year period. The complex interactions between the daily cycle of the atmosphere and vegetation CO2 exchange and the daily evolution of mixed layer entrainment of CO2 determines the CO2 variation pattern at a given height. The expanded BEPS can simulate within ñ2 ppm the hourly CO2 records at the 40 m measurement height. The annual totals of gross primary productivity (GPP), net primary productivity (NPP) and net ecosystem productivity (NEP), summed up from the hourly results, agree within 5% of previous estimates of BEPS at daily steps, indicating the internal consistency of the hourly model. The model is therefore ready for exploring changes in the CO2 record as affected by changes in the forest ecosystems upwind of the tower. Preliminary results indicate that the diurnal variation amplitude of CO2 has increased by 10-20% over the 10 years period, and this change can

  1. A Study on the Applicability of Kinetic Models for Shenfu Coal Char Gasification with CO2 at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Jinsheng Gao

    2009-07-01

    Full Text Available In this paper, measurements of the CO2 gasification kinetics for two types of Shenfu coal chars, which were respectively prepared by slow and rapid pyrolysis at temperatures of 950 °C and 1,400 °C, were performed by an isothermal thermo-gravimetric analysis under ambient pressure and elevated temperature conditions. Simultaneously, the applicability of the kinetic model for the CO2 gasification reaction of Shenfu coal chars was discussed. The results showed: (i the shrinking un-reacted core model was not appropriate to describe the gasification reaction process of Shenfu coal chars with CO2 in the whole experimental temperature range; (ii at the relatively low temperatures, the modified volumetric model was as good as the random pore model to simulate the CO2 gasification reaction of Shenfu coal chars, while at the elevated temperatures, the modified volumetric model was superior to the random pore model for this process; (iii the integral expression of the modified volumetric model was more favorable than the differential expression of that for fitting the experimental data. Moreover, by simply introducing a function: A = A★exp(ft, it was found that the extensive model of the modified volumetric model could make much better predictions than the modified volumetric model. It was recommended as a convenient empirical model for comprehensive simulation of Shenfu coal char gasification with under conditions close to those of entrained flow gasification.

  2. Exploratory Simulation Studies of Caprock Alteration Induced byStorage of CO2 in Depleted Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Gherardi, Fabrizio; Xu, Tianfu; Pruess, Karsten

    2005-11-23

    This report presents numerical simulations of isothermalreactive flows which might be induced in the caprock of an Italiandepleted gas reservoir by the geological sequestration of carbon dioxide.Our objective is to verify that CO2 geological disposal activitiesalready planned for the study area are safe and do not induce anyundesired environmental impact.Gas-water-rock interactions have beenmodelled under two different intial conditions, i.e., assuming that i)caprock is perfectly sealed, or ii) partially fractured. Field conditionsare better approximated in terms of the "sealed caprock model". Thefractured caprock model has been implemented because it permits toexplore the geochemical beahvior of the system under particularly severeconditions which are not currently encountered in the field, and then todelineate a sort of hypothetical maximum risk scenario.Major evidencessupporting the assumption of a sealed caprock stem from the fact that nogas leakages have been detected during the exploitation phase, subsequentreservoir repressurization due to the ingression of a lateral aquifer,and during several cycles of gas storage in the latest life of reservoirmanagement.An extensive program of multidisciplinary laboratory tests onrock properties, geochemical and microseismic monitoring, and reservoirsimulation studies is underway to better characterize the reservoir andcap-rock behavior before the performance of a planned CO2 sequestrationpilot test.In our models, fluid flow and mineral alteration are inducedin the caprock by penetration of high CO2 concentrations from theunderlying reservoir, i.e., it was assumed that large amounts of CO2 havebeen already injected at depth. The main focus is on the potential effectof these geochemical transformations on the sealing efficiency of caprockformations. Batch and multi-dimensional 1D and 2D modeling has been usedto investigate multicomponent geochemical processes. Our simulationsaccount for fracture-matrix interactions, gas

  3. Simulation of an Integrated Gasification Combined Cycle with Chemical-Looping Combustion and CO2 sequestration

    OpenAIRE

    Jiménez Alvaro, Ángel; López Paniagua, Ignacio; González Fernández, M. Celina; Rodríguez Martín, Javier; Nieto Carlier, Rafael

    2014-01-01

    Chemical-looping combustion allows an integration of CO2 capture in a thermal power plant without energy penalty; secondly, a less exergy destruction in the combustion chemical transformation is achieved, leading to a greater overall thermal efficiency. This paper focus on the study of the energetic performance of this concept of combustion in an integrated gasification combined cycle power plant when synthesis gas is used as fuel for the gas turbines. After thermodynamic modelling and optimi...

  4. Characteristics of mechanical wellbore failure and damage: Insights of discrete element modelling and application to CO2 storage

    NARCIS (Netherlands)

    Heege, J.H. ter; Orlic, B.; Hoedeman, G.C.

    2015-01-01

    Wellbore zonal isolation is particularly important for subsurface storage of CO2, where well integrity must be ensured for very long time spans. In this study, three dimensional discrete element models of wellbore systems have been used to simulate failure and damage of wellbore cement and

  5. Processes regulating pCO2 in the surface waters of the central eastern Gotland Sea: a model study

    Directory of Open Access Journals (Sweden)

    Bernd Schneider

    2011-09-01

    Full Text Available This work presents a one-dimensional simulation of the seasonal changes in CO2 partial pressure (pCO2. The results of the model were constrained using data from observations, which improved the model's ability to estimate nitrogen fixation in the central Baltic Sea and allowed the impact of nitrogen fixation on the ecological state of the Baltic Sea to be studied. The model used here is the public domain water-column model GOTM (General Ocean Turbulence Model, which in this study was coupled with a modifed Baltic Sea ecosystem model, ERGOM (The Baltic Sea Research Institute's ecosystem model. To estimate nitrogen fixation rates in the Gotland Sea, the ERGOM model was modified by including an additional cyanobacteria group able to fix nitrogen from March to June. Furthermore, the model was extended by a simple CO2 cycle. Variable C:P and N:P ratios, controlled by phosphate concentrations in ambient water, were used to represent cyanobacteria, detritus and sediment detritus. This approach improved the model's ability to reproduce sea-surface phosphate and pCO2 dynamics. The resulting nitrogen fixation rates in 2005 for the two simulations, with and without the additional cyanobacteria group, were 259 and 278 mmol N m-2 year-1respectively.

  6. Numerical investigation of CO2 storage in hydrocarbon field using a geomechanical-fluid coupling model

    Directory of Open Access Journals (Sweden)

    Guang Li

    2016-09-01

    Full Text Available Increasing pore pressure due to CO2 injection can lead to stress and strain changes of the reservoir. One of the safely standards for long term CO2 storage is whether stress and strain changes caused by CO2 injection will lead to irreversible mechanical damages of the reservoir and impact the integrity of caprock which could lead to CO2 leakage through previously sealing structures. Leakage from storage will compromise both the storage capacity and the perceived security of the project, therefore, a successful CO2 storage project requires large volumes of CO2 to be injected into storage site in a reliable and secure manner. Yougou hydrocarbon field located in Orods basin was chosen as storage site based on it's stable geological structure and low leakage risks. In this paper, we present a fluid pressure and stress-strain variations analysis for CO2 geological storage based on a geomechanical-fluid coupling model. Using nonlinear elasticity theory to describe the geomechanical part of the model, while using the Darcy's law to describe the fluid flow. Two parts are coupled together using the poroelasticity theory. The objectives of our work were: 1 evaluation of the geomechanical response of the reservoir to different CO2 injection scenarios. 2 assessment of the potential leakage risk of the reservoir caused by CO2 injection.

  7. Modeling a CO2 mineralization experiment of fractured peridotite from the Semail ophiolite/ Oman

    Science.gov (United States)

    Muller, Nadja; Zhang, Guoxiang; van Noort, Reinier; Spiers, Chris; Ten Grotenhuis, Saskia; Hoedeman, Gerco

    2010-05-01

    cell of the cold seal vessel than comparative experiments in large volume autoclaves and bench acid bath vials under lower and atmospheric pressure conditions. We attributed this observation to the limited water availability in the cold seal vessel, limiting the aqueous reaction of bi-carbonate formation and magnesite precipitation. To test this hypothesis, one of the cold seal vessel experiments at 20 MPa and 100°C was simulated with a reactive transport model, using TOUGHREACT. To simulate the actual experimental conditions, the model used a grid on mm and 100's of μm scale and a fractured peridotite medium with serpentine filling the fractures. The simulation produced dissolution comparable to the experiment and showed an effective shut down of the bi-carbonation reaction within one day after the start of the experiment. If the conditions of limited water supply seen in our experiments are applicable in a field setting, we could expect dissolution may be limited by the buffering of the pH and shut down of the bi-carbonate formation. Under field conditions water and CO2 will only flow in hydraulic induced fractures and the natural fracture network that is filled with serpentine and some carbonate. The simulation result and potential implication for the field application will require further experimental investigation in the lab or field in the future.

  8. Three dimensional global modeling of atmospheric CO2. Final technical report

    International Nuclear Information System (INIS)

    Fung, I.; Hansen, J.; Rind, D.

    1983-01-01

    A modeling effort has been initiated to study the prospects of extracting information on carbon dioxide sources and sinks from observed CO 2 variations. The approach uses a three-dimensional global transport model, based on winds from a 3-D general circulation model (GCM), to advect CO 2 noninteractively, i.e., as a tracer, with specified sources and sinks of CO 2 at the surface. This report identifies the 3-D model employed in this study and discusses biosphere, ocean and fossil fuel sources and sinks. Some preliminary model results are presented. 14 figures

  9. Evaluating the Capacity of Global CO2 Flux and Atmospheric Transport Models to Incorporate New Satellite Observations

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Erickson, D. J.; Denning, A. S.; Wofsy, S. C.; Andrews, A. E.

    2007-01-01

    As we enter the new era of satellite remote sensing for CO2 and other carbon cyclerelated quantities, advanced modeling and analysis capabilities are required to fully capitalize on the new observations. Model estimates of CO2 surface flux and atmospheric transport are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, and ultimately for future projections of carbon-climate interactions. For application to current, planned, and future remotely sensed CO2 data, it is desirable that these models are accurate and unbiased at time scales from less than daily to multi-annual and at spatial scales from several kilometers or finer to global. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 1998 through 2006. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at lxi degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-2), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to in situ observations at sites in Northern mid latitudes and the continental tropics. The influence of key process representations is inferred. We find that the model can resolve much of the hourly to synoptic variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The seasonal cycle and its

  10. Phase equilibrium of (CO2 + 1-aminopropyl-3-methylimidazolium bromide + water) electrolyte system and effects of aqueous medium on CO2 solubility: Experiment and modeling

    International Nuclear Information System (INIS)

    Chen, Ying; Guo, Kaihua; Bi, Yin; Zhou, Lan

    2017-01-01

    Highlights: • Phase and chemical equilibrium data for (CO 2 + [APMIm]Br + H 2 O) electrolyte system. • A modified eNRTL model for CO 2 solubility in the amino-based IL aqueous solution. • Effects of aqueous medium on both chemical and physical dissolution of CO 2 . • The correlative coefficient, R s ∗ , for the Henry’s constant of the solution. • New parameters for the segments interaction and the chemical equilibrium constants. - Abstract: New experimental data for solubility of carbon dioxide (CO 2 ) in the aqueous solution of 1-aminopropyl-3-methylimidazolium bromide ([APMIm]Br) with four different water mass fractions (0.559, 0.645, 0.765 and 0.858) at T = (278.15–348.15) K with an interval of T = 10 K and p = (0.1237–6.9143) MPa were presented. The electrolyte nonrandom two-liquid (eNRTL) model was modified to be applicable for an ionic liquid (IL) aqueous solution system, by introducing an idle factor β to illustrate the association effect of IL molecules. A solution Henry’s constant for CO 2 solubility in the IL aqueous solution was defined by introducing a correlative coefficient R s ∗ . The vapor-liquid phase equilibrium of the [APMIm]Br-H 2 O-CO 2 ternary system was successfully calculated with the modified eNRTL model. The chemical and physical mechanisms for the ionized CO 2 formation and the molecular CO 2 dissolved in the solution were identified. The effects of aqueous medium on both chemical and physical dissolution of CO 2 in the [APMIm]Br aqueous solution were studied, and a considerable enhancement of the solubility of CO 2 with increase of the water content in the solution was observed.

  11. Seasonal & Daily Amazon Column CO2 & CO Observations from Ground & Space Used to Evaluate Tropical Ecosystem Models

    Science.gov (United States)

    Dubey, M. K.; Parker, H. A.; Wennberg, P. O.; Wunch, D.; Jacobson, A. R.; Kawa, S. R.; Keppel-Aleks, G.; Basu, S.; O'Dell, C.; Frankenberg, C.; Michalak, A. M.; Baker, D. F.; Christofferson, B.; Restrepo-Coupe, N.; Saleska, S. R.; De Araujo, A. C.; Miller, J. B.

    2016-12-01

    The Amazon basin stores 150-200 PgC, exchanges 18 PgC with the atmosphere every year and has taken up 0.42-0.65 PgC/y over the past two decades. Despite its global significance, the response of the tropical carbon cycle to climate variability and change is ill constrained as evidenced by the large negative and positive feedbacks in future climate simulations. The complex interplay of radiation, water and ecosystem phenology remains unresolved in current tropical ecosystem models. We use high frequency regional scale TCCON observations of column CO2, CO and CH4 near Manaus, Brazil that began in October 2014 to understand the aforementioned interplay of processes in regulating biosphere-atmosphere exchange. We observe a robust daily column CO2 uptake of about 2 ppm (4 ppm to 0.5 ppm) over 8 hours and evaluate how it changes as we transition to the dry season. Back-trajectory calculations show that the daily CO2 uptake footprint is terrestrial and influenced by the heterogeneity of the Amazon rain forests. The column CO falls from above 120 ppb to below 80 ppb as we transition from the biomass burning to wet seasons. The daily mean column CO2 rises by 3 ppm from October through June. Removal of biomass burning, secular CO2 increase and variations from transport (by Carbon tracker simulations) implies an increase of 2.3 ppm results from tropical biospheric processes (respiration and photosynthesis). This is consistent with ground-based remote sensing and eddy flux observations that indicate that leaf development and demography drives the tropical carbon cycle in regions that are not water limited and is not considered in current models. We compare our observations with output from 7 CO2 inversion transport models with assimilated meteorology and find that while 5 models reproduce the CO2 seasonal cycle all of them under predict the daily drawdown of CO2 by a factor of 3. This indicates that the CO2 flux partitioning between photosynthesis and respiration is incorrect

  12. The Influence of Climate Change on CO2 and CH4 Concentration Near Closed Shaft - Numerical Simulations

    Science.gov (United States)

    Wrona, Paweł

    2017-09-01

    Given the scientific consensus pointing to climate change, the more extreme weather events associated with this will lead to deeper pressure drops. As has already been stated, pressure drops are the main cause of gas flow from underground sites to the surface. This article presents the results of numerical simulations of the change in distribution of CO2 and CH4 near a closed mining shaft under the predicted baric tendency. Simulations have been undertaken by means of the FDS software package with the Pyrosim graphical interface - a CFD tool for fire and ventilation analysis. Assumptions have been based on previous results of in-situ measurements. The results (determined for a height of 1m above the ground) were compared to the following levels (later in the text comparison levels): for CO2 0.1%vol. according to Pettenkoffer's scale and 2.5%vol. for CH4 as the half of Lower Explosive Limit (LEL). The results show that the deeper baric drops anticipated could lead to a wider spread of both greenhouse gases in the vicinity of the shaft, especially along the prevailing wind direction. According to the results obtained, CO2 and CH4 with concentrations above their comparison levels are expected at a distance greater than 50m from the shaft when wind is present for CO2 and at a distance of 4.5m for CH4. Subsequent analysis of the results enabled the determination of functions for describing the concentration of gases along the wind direction line under the projected pressure drop. The results relate to a particular case, although the model could easily be modified to any other example of gas emissions from underground sites.

  13. Bias and uncertainty of δ13CO2 isotopic mixing models

    Science.gov (United States)

    Zachary E. Kayler; Lisa Ganio; Mark Hauck; Thomas G. Pypker; Elizabeth W. Sulzman; Alan C. Mix; Barbara J. Bond

    2009-01-01

    The goal of this study was to evaluate how factorial combinations of two mixing models and two regression approaches (Keeling-OLS, Miller—Tans-OLS, Keeling-GMR, Miller—Tans-GMR) compare in small [CO2] range versus large[CO2] range regimes, with different combinations of...

  14. Using GEOS-5 Atmospheric Transport Simulations to Test the Consistency of Land- and Ocean- Carbon Fluxes with CO2 Observations

    Science.gov (United States)

    Ott, L. E.; Pawson, S.; Zhu, Z.; Brix, H.; Collatz, G. J.; Gregg, W. W.; Hill, C. N.; Menemenlis, D.; Potter, C. S.; Bowman, K. W.; Dutkiewicz, S.; Eldering, A.; Fisher, J. B.; Follows, M. J.; Gunson, M. R.; Jucks, K. W.; Kawa, S. R.; Liu, J.; Lee, M.

    2011-12-01

    Many components of the carbon cycle are constrained by a variety of remote sensing measurements. Observations of land surface parameters constrain estimates of carbon flux from terrestrial biosphere models while estimates of oceanic carbon fluxes are informed by satellite observations of ocean color and ocean properties. Atmospheric CO2 concentrations, which are governed by the balance of terrestrial, oceanic, and anthropogenic fluxes, are observed from space by an expanding suite of instruments (AIRS, TES, and GOSAT) in addition to being monitored by an extensive global network of surface stations. Additionally, atmospheric transport patterns simulated by NASA's GEOS-5 data analysis system are strongly influenced by observations of atmospheric state variables. NASA's Carbon Monitoring System Flux Pilot Project was created to quantify the constraints placed on carbon flux estimates by the current observing system and to assess what additional observational needs are required for future monitoring and attribution efforts. To this end, we have conducted an ensemble of GEOS-5 modeling studies using different combinations of two sets of land (NASA-CASA, CASA-GFED) and two sets of ocean (NOBM, ECCO2/Darwin) fluxes. Results from this ensemble of simulations are sampled at locations consistent with NOAA GMD and TCCON surface networks as well as locations of AIRS, TES, and GOSAT overpasses to quantify how surface flux uncertainty may be observed by different observing systems. Additionally, an ensemble of GEOS-5 simulations with alterations to subgrid-scale transport parameterizations is analyzed to compare model transport uncertainty with flux uncertainty. Our results indicate that uncertainty in both land and ocean flux estimates can introduce a large degree of variability into atmospheric CO2 distributions and that the magnitude of these differences is observable by existing satellite and in situ platforms. In contrast, transport uncertainty introduced by subgrid

  15. Development of a mechanistic model for prediction of CO2 capture from gas mixtures by amine solutions in porous membranes.

    Science.gov (United States)

    Ghadiri, Mehdi; Marjani, Azam; Shirazian, Saeed

    2017-06-01

    A mechanistic model was developed in order to predict capture and removal of CO 2 from air using membrane technology. The considered membrane was a hollow-fiber contactor module in which gas mixture containing CO 2 was assumed as feed while 2-amino-2-metyl-1-propanol (AMP) was used as an absorbent. The mechanistic model was developed according to transport phenomena taking into account mass transfer and chemical reaction between CO 2 and amine in the contactor module. The main aim of modeling was to track the composition and flux of CO 2 and AMP in the membrane module for process optimization. For modeling of the process, the governing equations were computed using finite element approach in which the whole model domain was discretized into small cells. To confirm the simulation findings, model outcomes were compared with experimental data and good consistency was revealed. The results showed that increasing temperature of AMP solution increases CO 2 removal in the hollow-fiber membrane contactor.

  16. Uncertainty in measurements of the photorespiratory CO2compensation point and its impact on models of leaf photosynthesis.

    Science.gov (United States)

    Walker, Berkley J; Orr, Douglas J; Carmo-Silva, Elizabete; Parry, Martin A J; Bernacchi, Carl J; Ort, Donald R

    2017-06-01

    Rates of carbon dioxide assimilation through photosynthesis are readily modeled using the Farquhar, von Caemmerer, and Berry (FvCB) model based on the biochemistry of the initial Rubisco-catalyzed reaction of net C 3 photosynthesis. As models of CO 2 assimilation rate are used more broadly for simulating photosynthesis among species and across scales, it is increasingly important that their temperature dependencies are accurately parameterized. A vital component of the FvCB model, the photorespiratory CO 2 compensation point (Γ * ), combines the biochemistry of Rubisco with the stoichiometry of photorespiratory release of CO 2 . This report details a comparison of the temperature response of Γ * measured using different techniques in three important model and crop species (Nicotiana tabacum, Triticum aestivum, and Glycine max). We determined that the different Γ * determination methods produce different temperature responses in the same species that are large enough to impact higher-scale leaf models of CO 2 assimilation rate. These differences are largest in N. tabacum and could be the result of temperature-dependent increases in the amount of CO 2 lost from photorespiration per Rubisco oxygenation reaction.

  17. A new pilot absorber for CO2 capture from flue gases: Measuring and modelling capture with MEA solution

    DEFF Research Database (Denmark)

    Sønderby, Tim L.; Carlsen, Kim B.; Fosbøl, Philip Loldrup

    2013-01-01

    recovery increases with an increase in flow rate of absorbent and absorption height, it decreases as the lean CO2-loading of the absorbent increases. In addition it has been possible to obtain temperature bulges in the bottom part of the absorber by the applied operation conditions. Bulges are observed...... at liquid flows around 4.2L/min and below. The results showed that is was possible to achieve 80% recovery with 3.3m absorption height and a liquid flow of 2.1L/min. The simulations show good agreement with the experimental values, although slight deviations arise as the CO2-loading increases......A pilot absorber column for CO2 recovery from flue gases was constructed and tested with aqueous 30wt% monoethanolamine (MEA), a primary amine, as capture solvent. The pilot plant data were compared with a mathematical rate based packed-column model. The simulation results compared well...

  18. Modeling and validation of on-road CO2 emissions inventories at the urban regional scale

    International Nuclear Information System (INIS)

    Brondfield, Max N.; Hutyra, Lucy R.; Gately, Conor K.; Raciti, Steve M.; Peterson, Scott A.

    2012-01-01

    On-road emissions are a major contributor to rising concentrations of atmospheric greenhouse gases. In this study, we applied a downscaling methodology based on commonly available spatial parameters to model on-road CO 2 emissions at the 1 × 1 km scale for the Boston, MA region and tested our approach with surface-level CO 2 observations. Using two previously constructed emissions inventories with differing spatial patterns and underlying data sources, we developed regression models based on impervious surface area and volume-weighted road density that could be scaled to any resolution. We found that the models accurately reflected the inventories at their original scales (R 2 = 0.63 for both models) and exhibited a strong relationship with observed CO 2 mixing ratios when downscaled across the region. Moreover, the improved spatial agreement of the models over the original inventories confirmed that either product represents a viable basis for downscaling in other metropolitan regions, even with limited data. - Highlights: ► We model two on-road CO 2 emissions inventories using common spatial parameters. ► Independent CO 2 observations are used to validate the emissions models. ► The downscaled emissions models capture the urban spatial heterogeneity of Boston. ► Emissions estimates show a strong non-linear relationship with observed CO 2 . ► Our study is repeatable, even in areas with limited data. - This work presents a new, reproducible methodology for downscaling and validating on-road CO 2 emissions estimates.

  19. Uncertainty in geochemical modelling of CO2 and calcite dissolution in NaCl solutions due to different modelling codes and thermodynamic databases

    International Nuclear Information System (INIS)

    Haase, Christoph; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

    2013-01-01

    Highlights: • CO 2 and calcite dissolution is calculated. • The codes PHREEQC, Geochemist’s Workbench, EQ3/6, and FactSage are used. • Comparison with Duan and Li (2008) shows lowest deviation using phreeqc.dat and wateq4f.dat. • Using Pitzer databases does not improve accurate calculations. • Uncertainty in dissolved CO 2 is largest using the geochemical models. - Abstract: A prognosis of the geochemical effects of CO 2 storage induced by the injection of CO 2 into geologic reservoirs or by CO 2 leakage into the overlaying formations can be performed by numerical modelling (non-invasive) and field experiments. Until now the research has been focused on the geochemical processes of the CO 2 reacting with the minerals of the storage formation, which mostly consists of quartzitic sandstones. Regarding the safety assessment the reactions between the CO 2 and the overlaying formations in the case of a CO 2 leakage are of equal importance as the reactions in the storage formation. In particular, limestone formations can react very sensitively to CO 2 intrusion. The thermodynamic parameters necessary to model these reactions are not determined explicitly through experiments at the total range of temperature and pressure conditions and are thus extrapolated by the simulation code. The differences in the calculated results lead to different calcite and CO 2 solubilities and can influence the safety issues. This uncertainty study is performed by comparing the computed results, applying the geochemical modelling software codes The Geochemist’s Workbench, EQ3/6, PHREEQC and FactSage/ChemApp and their thermodynamic databases. The input parameters (1) total concentration of the solution, (2) temperature and (3) fugacity are varied within typical values for CO 2 reservoirs, overlaying formations and close-to-surface aquifers. The most sensitive input parameter in the system H 2 O–CO 2 –NaCl–CaCO 3 for the calculated range of dissolved calcite and CO 2 is the

  20. Using eddy covariance of CO2, 13CO2 and CH4, continuous soil respiration measurements, and PhenoCams to constrain a process-based biogeochemical model for carbon market-funded wetland restoration

    Science.gov (United States)

    Oikawa, P. Y.; Baldocchi, D. D.; Knox, S. H.; Sturtevant, C. S.; Verfaillie, J. G.; Dronova, I.; Jenerette, D.; Poindexter, C.; Huang, Y. W.

    2015-12-01

    % of observed annual budgets of CO2 and CH4, respectively). The use of multiple data streams is critical for constraining parameters and reducing uncertainty in model predictions, thereby providing accurate simulation of greenhouse gas exchange in a wetland restoration project with implications for C market-funded wetland restoration worldwide.

  1. Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study

    Directory of Open Access Journals (Sweden)

    A. M. Michalak

    2010-07-01

    Full Text Available A series of synthetic data experiments is performed to investigate the ability of a regional atmospheric inversion to estimate grid-scale CO2 fluxes during the growing season over North America. The inversions are performed within a geostatistical framework without the use of any prior flux estimates or auxiliary variables, in order to focus on the atmospheric constraint provided by the nine towers collecting continuous, calibrated CO2 measurements in 2004. Using synthetic measurements and their associated concentration footprints, flux and model-data mismatch covariance parameters are first optimized, and then fluxes and their uncertainties are estimated at three different temporal resolutions. These temporal resolutions, which include a four-day average, a four-day-average diurnal cycle with 3-hourly increments, and 3-hourly fluxes, are chosen to help assess the impact of temporal aggregation errors on the estimated fluxes and covariance parameters. Estimating fluxes at a temporal resolution that can adjust the diurnal variability is found to be critical both for recovering covariance parameters directly from the atmospheric data, and for inferring accurate ecoregion-scale fluxes. Accounting for both spatial and temporal a priori covariance in the flux distribution is also found to be necessary for recovering accurate a posteriori uncertainty bounds on the estimated fluxes. Overall, the results suggest that even a fairly sparse network of 9 towers collecting continuous CO2 measurements across the continent, used with no auxiliary information or prior estimates of the flux distribution in time or space, can be used to infer relatively accurate monthly ecoregion scale CO2 surface fluxes over North America within estimated uncertainty bounds. Simulated random transport error is shown to decrease the quality of flux estimates in under-constrained areas at the ecoregion scale, although the uncertainty bounds remain realistic. While these synthetic

  2. Stomatal Frequency and Atmospheric CO2: a Model Based on Photosynthesis and Gaseous Diffusion

    Science.gov (United States)

    Roth-Nebelsick, A.; Konrad, W.

    2004-12-01

    Gaseous exchange in land plants occurs via micropores on the plant surface, the stomata. The stomatal frequency (SF) of leaves has attracted considerable interest with respect to increasing atmospheric CO2 since Woodward (1987) demonstrated that this parameter changes inversely with CO2 in various species. The response is due to 1) individual phenotypic plasticity and 2) evolutionary change, depending on the considered time scale. The SF-CO2 response is regarded to represent a valuable device for determining past atmospheric CO2 concentration and SF data from fossil plant material are therefore often used as CO2 proxies. There are, however, numerous difficulties which have to be considered, such as: 1) high variance of the data, especially for fossil material, 2) interspecific differences of the response, 3) the CO2 ceiling (= weak or no response under CO2 concentration higher than ambient) and 4) differences between short-term and long-term responses. Although processes related to plant gaseous exchange are assumed to represent the causal basis for the response, no clear explanatory model has yet been proposed and even doubts have emerged about the real existence of this phenomenon. In this contribution it is shown that results obtained with a model based on diffusion and assimilation suggest that the SF-CO2 response is a structural adjustment of maximum stomatal conductance. The results 1) offer a clear explanation for the often observed weak response of stomatal frequency to CO2 levels higher than ambient, 2) provide a simple equation for calculating ancient CO2 levels from stomatal data, and 3) can contribute to predictions concerning plant reactions to elevated CO2 levels in the future.

  3. Gasification under CO2–Steam Mixture: Kinetic Model Study Based on Shared Active Sites

    Directory of Open Access Journals (Sweden)

    Xia Liu

    2017-11-01

    Full Text Available In this work, char gasification of two coals (i.e., Shenfu bituminous coal and Zunyi anthracite and a petroleum coke under a steam and CO2 mixture (steam/CO2 partial pressures, 0.025–0.075 MPa; total pressures, 0.100 MPa and CO2/steam chemisorption of char samples were conducted in a Thermogravimetric Analyzer (TGA. Two conventional kinetic models exhibited difficulties in exactly fitting the experimental data of char–steam–CO2 gasification. Hence, a modified model based on Langmuir–Hinshelwood model and assuming that char–CO2 and char–steam reactions partially shared active sites was proposed and had indicated high accuracy for estimating the interactions in char–steam–CO2 reaction. Moreover, it was found that two new model parameters (respectively characterized as the amount ratio of shared active sites to total active sites in char–CO2 and char–steam reactions in the modified model hardly varied with gasification conditions, and the results of chemisorption indicate that these two new model parameters mainly depended on the carbon active sites in char samples.

  4. MODELING POTENTIAL IMPACTS OF SO2 CO-INJECTED WITH CO2 ON THE KNOX GROUP, WESTERN KENTUCKY

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Junfeng; Harris, David; Leetaru, Hannes

    2014-09-30

    Understanding potential long-term impacts of CO2 impurities, such as sulfur and nitrogen compounds, on deep carbon storage reservoirs is of considerable interest because co-injection of the impurities with CO2 can bring significant economic and environmental benefits. The Cambrian–Ordovician Knox Group, a thick sequence of dolostone (Beekmantown Dolomite) with minor dolomitic sandstone (Gunter Sandstone), in western Kentucky, USA, has been evaluated as a prospective CO2 sequestration target. In this study, TOUGHREACT was used to build 1-D radial models to simulate the potential impacts of co-injected CO2 and SO2 on minerals, pore fluids, and porosity and permeability in the Beekmantown Dolomite and the Gunter Sandstone. Co-injection of a mass ratio of 2.5 percent SO2 and 97.5 percent CO2, representative of flue gas from coal-fired plants, was simulated and the co-injection simulations were compared to models with CO2 only injections. The model results suggest that the major impacts of added SO2 for both the Beekmantown and the Gunter rocks were significant enhancement of dissolution of dolomite and precipitation of anhydrite, leading to noticeable increases in porosity and permeability. The Gunter Sandstone appeared to be more active with SO2 than the Beekmantown Dolomite. More dolomite was dissolved in the Gunter than in the Beekmantown with the same SO2 impurity. Consequently, porosity was raised more in the Gunter than in the Beekmantown. On the other hand, the impacts on aluminosilicate minerals appeared to be insignificant in both reservoirs, slightly changing the rates of precipitation/dissolution but the overall reaction paths remained the same.

  5. Climate change due to the gradual increase in atmospheric CO2: a climate system model sensitivity study

    International Nuclear Information System (INIS)

    Park, H.S.; Joh, M.

    2005-01-01

    A numerical experiment investigating climate change due to the gradual increase in atmospheric carbon dioxide (CO 2 ) has been performed with the community climate system model (CCSM) developed by National Center for Atmospheric Research (NCAR). Composed of four independent component models simulating the Earth's atmosphere, ocean, land surface, and sea-ice and one central coupler, the CCSM is used to simulate and understand the Earth's past, present and future climate states. The model experiment consists of a control run with a fixed atmospheric CO 2 concentration at a standardized value for 1990 to 2000 (355 ppmv) and a transient run with a gradually increased atmospheric CO 2 at the rate of 1% per year. ja The initial CO 2 concentration of the transient run is 355 ppmv. Each run has been performed for 80 simulated years. In this experiment, climate change due to the gradually increased atmospheric CO 2 is defined as the difference between the results from the transient and control runs. At the time of CO 2 doubling (about year 70), the globally averaged surface air temperature increases by 1.25 C. The surface air temperature increases are more predominant over the higher-latitude land areas than over other areas, especially in boreal winter. With an increase in the surface air temperature, there is a decrease in the diurnal temperature range, with the nighttime minimum temperature increasing more than the daytime maximum temperature. And air temperature shows tropospheric warming and stratospheric cooling causing the strong temperature gradient and polar jet intensifications. (orig.)

  6. Surface energy balances of three general circulation models: Current climate and response to increasing atmospheric CO2

    International Nuclear Information System (INIS)

    Gutowski, W.J.; Gutzler, D.S.; Portman, D.; Wang, W.C.

    1988-04-01

    The surface energy balance simulated by state-of-the-art general circulation models at GFDL, GISS and NCAR for climates with current levels of atmospheric CO 2 concentration (control climate) and with twice the current levels. The work is part of an effort sponsored by the US Department of Energy to assess climate simulations produced by these models. The surface energy balance enables us to diagnose differences between models in surface temperature climatology and sensitivity to doubling CO 2 in terms of the processes that control surface temperature. Our analysis compares the simulated balances by averaging the fields of interest over a hierarchy of spatial domains ranging from the entire globe down to regions a few hundred kilometers across

  7. Evaluation of CO2-Fluid-Rock Interaction in Enhanced Geothermal Systems: Field-Scale Geochemical Simulations

    Directory of Open Access Journals (Sweden)

    Feng Pan

    2017-01-01

    Full Text Available Recent studies suggest that using supercritical CO2 (scCO2 instead of water as a heat transmission fluid in Enhanced Geothermal Systems (EGS may improve energy extraction. While CO2-fluid-rock interactions at “typical” temperatures and pressures of subsurface reservoirs are fairly well known, such understanding for the elevated conditions of EGS is relatively unresolved. Geochemical impacts of CO2 as a working fluid (“CO2-EGS” compared to those for water as a working fluid (H2O-EGS are needed. The primary objectives of this study are (1 constraining geochemical processes associated with CO2-fluid-rock interactions under the high pressures and temperatures of a typical CO2-EGS site and (2 comparing geochemical impacts of CO2-EGS to geochemical impacts of H2O-EGS. The St. John’s Dome CO2-EGS research site in Arizona was adopted as a case study. A 3D model of the site was developed. Net heat extraction and mass flow production rates for CO2-EGS were larger compared to H2O-EGS, suggesting that using scCO2 as a working fluid may enhance EGS heat extraction. More aqueous CO2 accumulates within upper- and lower-lying layers than in the injection/production layers, reducing pH values and leading to increased dissolution and precipitation of minerals in those upper and lower layers. Dissolution of oligoclase for water as a working fluid shows smaller magnitude in rates and different distributions in profile than those for scCO2 as a working fluid. It indicates that geochemical processes of scCO2-rock interaction have significant effects on mineral dissolution and precipitation in magnitudes and distributions.

  8. Hydro-mechanical simulations of well abandonment at the Ketzin pilot site for CO2 storage verify wellbore system integrity

    Science.gov (United States)

    Unger, Victoria; Kempka, Thomas

    2015-04-01

    In geological underground utilisation, operating and abandoned wells have been identified as a main potential leakage pathways for reservoir fluids. In the scope of the well abandonment procedure currently carried out at the Ketzin pilot site for CO2 storage in Germany, a hydro-mechanical model was built to carry out a coupled analysis of the integrity in the entire wellbore system. The main aim of the present study was to assess the impacts of stress changes associated with CO2 injection as well as the cement backfill undertaken in the scope of well abandonment. A numerical model comprising cement sheaths, steel casings, tubing, multiple packers and wellbore annuli was implemented to enable a detailed representation of the entire wellbore system. The numerical model grid has a horizontal discretisation of 5 m x 5 m to focus on near wellbore effects, whereby element sizes increase with increasing distance from the wellbore. Vertical grid discretisation uses a tartan grid type over the entire model thickness of 1,500 m to ensure a sufficient discretisation of all wellbore system elements as well as of the reservoir unit. The total number of elements amounts to 210,672. Mechanical model parameters were taken from geological, drilling, logging and laboratory test data based on Ketzin pilot site-specific information as well as related literature (Kempka et al., 2014). The coupled calculations were performed using an elasto-plastic constitutive law, whereby an initial simulation run ensured a static mechanical equilibrium to represent the initial state before the start of CO2 injection. Thereto, gravitational load of the overburden rocks and pore pressure distribution following available well logs were integrated for initial model parameterisation including a normal faulting stress regime defined by a horizontal to vertical total stress ratio of 0.85. A correction accounting for the temperature and pressure dependent CO2 density was carried out in advance of each

  9. A model analysis of climate and CO2 controls on tree growth in a semi-arid woodland

    Science.gov (United States)

    Li, G.; Harrison, S. P.; Prentice, I. C.

    2015-03-01

    We used a light-use efficiency model of photosynthesis coupled with a dynamic carbon allocation and tree-growth model to simulate annual growth of the gymnosperm Callitris columellaris in the semi-arid Great Western Woodlands, Western Australia, over the past 100 years. Parameter values were derived from independent observations except for sapwood specific respiration rate, fine-root turnover time, fine-root specific respiration rate and the ratio of fine-root mass to foliage area, which were estimated by Bayesian optimization. The model reproduced the general pattern of interannual variability in radial growth (tree-ring width), including the response to the shift in precipitation regimes that occurred in the 1960s. Simulated and observed responses to climate were consistent. Both showed a significant positive response of tree-ring width to total photosynthetically active radiation received and to the ratio of modeled actual to equilibrium evapotranspiration, and a significant negative response to vapour pressure deficit. However, the simulations showed an enhancement of radial growth in response to increasing atmospheric CO2 concentration (ppm) ([CO2]) during recent decades that is not present in the observations. The discrepancy disappeared when the model was recalibrated on successive 30-year windows. Then the ratio of fine-root mass to foliage area increases by 14% (from 0.127 to 0.144 kg C m-2) as [CO2] increased while the other three estimated parameters remained constant. The absence of a signal of increasing [CO2] has been noted in many tree-ring records, despite the enhancement of photosynthetic rates and water-use efficiency resulting from increasing [CO2]. Our simulations suggest that this behaviour could be explained as a consequence of a shift towards below-ground carbon allocation.

  10. Pore-scale observation and 3D simulation of wettability effects on supercritical CO2 - brine immiscible displacement in drainage

    Science.gov (United States)

    Hu, R.; Wan, J.; Chen, Y.

    2016-12-01

    Wettability is a factor controlling the fluid-fluid displacement pattern in porous media and significantly affects the flow and transport of supercritical (sc) CO2 in geologic carbon sequestration. Using a high-pressure micromodel-microscopy system, we performed drainage experiments of scCO2 invasion into brine-saturated water-wet and intermediate-wet micromodels; we visualized the scCO2 invasion morphology at pore-scale under reservoir conditions. We also performed pore-scale numerical simulations of the Navier-Stokes equations to obtain 3D details of fluid-fluid displacement processes. Simulation results are qualitatively consistent with the experiments, showing wider scCO2 fingering, higher percentage of scCO2 and more compact displacement pattern in intermediate-wet micromodel. Through quantitative analysis based on pore-scale simulation, we found that the reduced wettability reduces the displacement front velocity, promotes the pore-filling events in the longitudinal direction, delays the breakthrough time of invading fluid, and then increases the displacement efficiency. Simulated results also show that the fluid-fluid interface area follows a unified power-law relation with scCO2 saturation, and show smaller interface area in intermediate-wet case which suppresses the mass transfer between the phases. These pore-scale results provide insights for the wettability effects on CO2 - brine immiscible displacement in geologic carbon sequestration.

  11. The effects of climatic variation in Europe on the yield response of spring wheat cv. Minaret to elevated CO2 and O3: an analysis of open-top chamber experiments by means of two crop growth simulation models

    NARCIS (Netherlands)

    Oijen, van M.; Ewert, F.

    1999-01-01

    In the ESPACE-Wheat programme, 25 open-top chamber experiments were carried out in 1994, 1995 and 1996, on nine locations, divided over eight European countries. In most experiments, spring wheat cv. Minaret was subjected to two levels of atmospheric CO2 and two levels of ozone. Grain yields in the

  12. Canopy development of a model herbaceous community exposed to elevated atmospheric CO2 and soil nutrients.

    Science.gov (United States)

    Hartz-Rubin, Jennifer S.; DeLucia, Evan H.

    2001-10-01

    To test the prediction that elevated CO2 increases the maximum leaf area index (LAI) through a stimulation of photosynthesis, we exposed model herbaceous communities to two levels of CO2 crossed with two levels of soil fertility. Elevated CO2 stimulated the initial rate of canopy development and increased cumulative LAI integrated over the growth period, but it had no effect on the maximum LAI. In contrast to CO2, increased soil nutrient availability caused a substantial increase in maximum LAI. Elevated CO2 caused a slight increase in leaf area and nitrogen allocated to upper canopy layers and may have stimulated leaf turnover deep in the canopy. Gas exchange measurements of intact communities made near the time of maximum LAI indicated that soil nutrient availability, but not CO2 enrichment, caused a substantial stimulation of net ecosystem carbon exchange. These data do not support our prediction of a higher maximum LAI by elevated CO2 because the initial stimulation of LAI diminished by the end of the growth period. However, early in development, leaf area and carbon assimilation of communities may have been greatly enhanced. These results suggest that the rate of canopy development in annual communities may be accelerated with future increases in atmospheric CO2 but that maximum LAI is set by soil fertility.

  13. Functional response of a near-surface soil microbial community to a simulated underground CO2 storage leak.

    Directory of Open Access Journals (Sweden)

    Sergio E Morales

    Full Text Available Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO2 emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO2 storage leak scenario, we demonstrate how CO2 flow upward through the soil column altered both the abundance (DNA and activity (mRNA of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO2, they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO2 levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface CO2 using FACE (Free-Air CO2 Enrichment systems, suggesting that microbial community response to CO2 seepage from the subsurface might differ from its response to atmospheric CO2 increases.

  14. Mechanistic insights into electrochemical reduction of CO2over Ag using density functional theory and transport models.

    Science.gov (United States)

    Singh, Meenesh R; Goodpaster, Jason D; Weber, Adam Z; Head-Gordon, Martin; Bell, Alexis T

    2017-10-17

    Electrochemical reduction of CO 2 using renewable sources of electrical energy holds promise for converting CO 2 to fuels and chemicals. Since this process is complex and involves a large number of species and physical phenomena, a comprehensive understanding of the factors controlling product distribution is required. While the most plausible reaction pathway is usually identified from quantum-chemical calculation of the lowest free-energy pathway, this approach can be misleading when coverages of adsorbed species determined for alternative mechanism differ significantly, since elementary reaction rates depend on the product of the rate coefficient and the coverage of species involved in the reaction. Moreover, cathode polarization can influence the kinetics of CO 2 reduction. Here, we present a multiscale framework for ab initio simulation of the electrochemical reduction of CO 2 over an Ag(110) surface. A continuum model for species transport is combined with a microkinetic model for the cathode reaction dynamics. Free energies of activation for all elementary reactions are determined from density functional theory calculations. Using this approach, three alternative mechanisms for CO 2 reduction were examined. The rate-limiting step in each mechanism is **COOH formation at higher negative potentials. However, only via the multiscale simulation was it possible to identify the mechanism that leads to a dependence of the rate of CO formation on the partial pressure of CO 2 that is consistent with experiments. Simulations based on this mechanism also describe the dependence of the H 2 and CO current densities on cathode voltage that are in strikingly good agreement with experimental observation.

  15. Backscatter measurements of aerosolized CB simulants with a frequency agile CO2 lidar

    Science.gov (United States)

    Vanderbeek, Richard; Gurton, Kristan

    2004-02-01

    A novel windowless chamber was developed to allow aerosol backscatter measurements with a frequency-agile CO2 lidar. The chamber utilizes curtains of air to contain the cloud, thus preventing the inevitable backscatter off of conventional windows from corrupting the desired measurements. This feature is critical because the CO2 lidar has a long (1 μs) pulse and the backscatter off the window cannot be temporally separated from the backscatter off the aerosol in the chamber. The chamber was designed for testing with a variety of CB simulants and interferents in both vapor and aerosol form and has been successfully shown to contain a cloud of known size, concentration, and particle size distribution for 10-15 minutes. This paper shows the results using Arizona road dust that was screened by the manufacturer into 0-3 μm and 5-10 μm particle size distributions. The measurements clearly show the effect of size distribution on the infrared backscatter coefficients as well as the dynamic nature of the size distribution for a population of aerosols. The test methodology and experimental results are presented.

  16. CO2 conversion by plasma technology: insights from modeling the plasma chemistry and plasma reactor design

    Science.gov (United States)

    Bogaerts, A.; Berthelot, A.; Heijkers, S.; Kolev, St.; Snoeckx, R.; Sun, S.; Trenchev, G.; Van Laer, K.; Wang, W.

    2017-06-01

    In recent years there has been growing interest in the use of plasma technology for CO2 conversion. To improve this application, a good insight into the underlying mechanisms is of great importance. This can be obtained from modeling the detailed plasma chemistry in order to understand the chemical reaction pathways leading to CO2 conversion (either in pure form or mixed with another gas). Moreover, in practice, several plasma reactor types are being investigated for CO2 conversion, so in addition it is essential to be able to model these reactor geometries so that their design can be improved, and the most energy efficient CO2 conversion can be achieved. Modeling the detailed plasma chemistry of CO2 conversion in complex reactors is, however, very time-consuming. This problem can be overcome by using a combination of two different types of model: 0D chemical reaction kinetics models are very suitable for describing the detailed plasma chemistry, while the characteristic features of different reactor geometries can be studied by 2D or 3D fluid models. In the first instance the latter can be developed in argon or helium with a simple chemistry to limit the calculation time; however, the ultimate aim is to implement the more complex CO2 chemistry in these models. In the present paper, examples will be given of both the 0D plasma chemistry models and the 2D and 3D fluid models for the most common plasma reactors used for CO2 conversion in order to emphasize the complementarity of both approaches. Furthermore, based on the modeling insights, the paper discusses the possibilities and limitations of plasma-based CO2 conversion in different types of plasma reactors, as well as what is needed to make further progress in this field.

  17. A regional CO2 observing system simulation experiment for the ASCENDS satellite mission

    Science.gov (United States)

    Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Baker, D. F.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Zaccheo, T. S.

    2014-12-01

    Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions) generated by the Stochastic Time-Inverted Lagrangian Transport (STILT) model in combination with the Weather Research and Forecasting (WRF) model in a regional Bayesian synthesis inversion. The regional Lagrangian particle dispersion model framework is well suited to make use of ASCENDS observations to constrain weekly fluxes in North America at a high resolution, in this case at 1° latitude × 1° longitude. We consider random measurement errors only, modeled as a function of the mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the grid scale and weekly resolution, the largest uncertainty reductions, on the order of 50%, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 μm candidate wavelength than for a 2.05 μm wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada). Uncertainty reductions at the annual biome scale range from ~40% to ~75% across our four instrument design cases and

  18. Modeling CO2-Water-Mineral Wettability and Mineralization for Carbon Geosequestration.

    Science.gov (United States)

    Liang, Yunfeng; Tsuji, Shinya; Jia, Jihui; Tsuji, Takeshi; Matsuoka, Toshifumi

    2017-07-18

    Carbon dioxide (CO 2 ) capture and storage (CCS) is an important climate change mitigation option along with improved energy efficiency, renewable energy, and nuclear energy. CO 2 geosequestration, that is, to store CO 2 under the subsurface of Earth, is feasible because the world's sedimentary basins have high capacity and are often located in the same region of the world as emission sources. How CO 2 interacts with the connate water and minerals is the focus of this Account. There are four trapping mechanisms that keep CO 2 in the pores of subsurface rocks: (1) structural trapping, (2) residual trapping, (3) dissolution trapping, and (4) mineral trapping. The first two are dominated by capillary action, where wettability controls CO 2 and water two-phase flow in porous media. We review state-of-the-art studies on CO 2 /water/mineral wettability, which was found to depend on pressure and temperature conditions, salt concentration in aqueous solutions, mineral surface chemistry, and geometry. We then review some recent advances in mineral trapping. First, we show that it is possible to reproduce the CO 2 /water/mineral wettability at a wide range of pressures using molecular dynamics (MD) simulations. As the pressure increases, CO 2 gas transforms into a supercritical fluid or liquid at ∼7.4 MPa depending on the environmental temperature. This transition leads to a substantial decrease of the interfacial tension between CO 2 and reservoir brine (or pure water). However, the wettability of CO 2 /water/rock systems depends on the type of rock surface. Recently, we investigated the contact angle of CO 2 /water/silica systems with two different silica surfaces using MD simulations. We found that contact angle increased with pressure for the hydrophobic (siloxane) surface while it was almost constant for the hydrophilic (silanol) surface, in excellent agreement with experimental observations. Furthermore, we found that the CO 2 thin films at the CO 2 -hydrophilic

  19. An energy balance perspective on regional CO2-induced temperature changes in CMIP5 models

    Science.gov (United States)

    Räisänen, Jouni

    2017-05-01

    An energy balance decomposition of temperature changes is conducted for idealized transient CO2-only simulations in the fifth phase of the Coupled Model Intercomparison Project. The multimodel global mean warming is dominated by enhanced clear-sky greenhouse effect due to increased CO2 and water vapour, but other components of the energy balance substantially modify the geographical and seasonal patterns of the change. Changes in the net surface energy flux are important over the oceans, being especially crucial for the muted warming over the northern North Atlantic and for the seasonal cycle of warming over the Arctic Ocean. Changes in atmospheric energy flux convergence tend to smooth the gradients of temperature change and reduce its land-sea contrast, but they also amplify the seasonal cycle of warming in northern North America and Eurasia. The three most important terms for intermodel differences in warming are the changes in the clear-sky greenhouse effect, clouds, and the net surface energy flux, making the largest contribution to the standard deviation of annual mean temperature change in 34, 29 and 20 % of the world, respectively. Changes in atmospheric energy flux convergence mostly damp intermodel variations of temperature change especially over the oceans. However, the opposite is true for example in Greenland and Antarctica, where the warming appears to be substantially controlled by heat transport from the surrounding sea areas.

  20. Experimental and CFD modelling for thermal comfort and CO2 concentration in office building

    Science.gov (United States)

    Kabrein, H.; Hariri, A.; Leman, A. M.; Yusof, M. Z. M.; Afandi, A.

    2017-09-01

    Computational fluid dynamic CFD was used for simulating air flow, indoor air distribution and contamination concentration. Gases pollution and thermal discomfort affected occupational health and productivity of work place. The main objectives of this study are to investigate the impact of air change rate in CO2 concentration and to estimate the profile of CO2 concentration in the offices building. The thermal comfort and gases contamination are investigated by numerical analysis CFD which was validated by experiment. Thus the air temperature, air velocity and CO2 concentration were measured at several points in the chamber with four occupants. Comparing between experimental and numerical results showed good agreement. In addition, the CO2 concentration around human recorded high, compared to the other area. Moreover, the thermal comfort in this study is within the ASHRAE standard 55-2004.

  1. Decadal trends in the seasonal-cycle amplitude of terrestrial CO2 exchange resulting from the ensemble of terrestrial biosphere models

    Directory of Open Access Journals (Sweden)

    Akihiko Ito

    2016-05-01

    Full Text Available The seasonal-cycle amplitude (SCA of the atmosphere–ecosystem carbon dioxide (CO2 exchange rate is a useful metric of the responsiveness of the terrestrial biosphere to environmental variations. It is unclear, however, what underlying mechanisms are responsible for the observed increasing trend of SCA in atmospheric CO2 concentration. Using output data from the Multi-scale Terrestrial Model Intercomparison Project (MsTMIP, we investigated how well the SCA of atmosphere–ecosystem CO2 exchange was simulated with 15 contemporary terrestrial ecosystem models during the period 1901–2010. Also, we made attempt to evaluate the contributions of potential mechanisms such as atmospheric CO2, climate, land-use, and nitrogen deposition, through factorial experiments using different combinations of forcing data. Under contemporary conditions, the simulated global-scale SCA of the cumulative net ecosystem carbon flux of most models was comparable in magnitude with the SCA of atmospheric CO2 concentrations. Results from factorial simulation experiments showed that elevated atmospheric CO2 exerted a strong influence on the seasonality amplification. When the model considered not only climate change but also land-use and atmospheric CO2 changes, the majority of the models showed amplification trends of the SCAs of photosynthesis, respiration, and net ecosystem production (+0.19 % to +0.50 % yr−1. In the case of land-use change, it was difficult to separate the contribution of agricultural management to SCA because of inadequacies in both the data and models. The simulated amplification of SCA was approximately consistent with the observational evidence of the SCA in atmospheric CO2 concentrations. Large inter-model differences remained, however, in the simulated global tendencies and spatial patterns of CO2 exchanges. Further studies are required to identify a consistent explanation for the simulated and observed amplification trends, including their

  2. Impact of geological heterogeneity on CO2 sequestration: from outcrop to simulator

    OpenAIRE

    Senger, Kim

    2013-01-01

    Increased anthropogenic emission of carbon dioxide (CO2) into the Earth’s atmosphere since the industrial revolution has enhanced the greenhouse effect and contributed to global climate change. Controlling atmospheric CO2 emissions is thus essential to mitigate the environmental and socio-economic consequences related to these changes. Carbon capture and storage (CCS) was proposed as one possible option to control anthropogenic CO2 emissions, and is particularly viable at CO2 p...

  3. A Microscale Model for Combined CO2 Diffusion and Photosynthesis in Leaves

    Science.gov (United States)

    Ho, Quang Tri; Verboven, Pieter; Yin, Xinyou; Struik, Paul C.; Nicolaï, Bart M.

    2012-01-01

    Transport of CO2 in leaves was investigated by combining a 2-D, microscale CO2 transport model with photosynthesis kinetics in wheat (Triticum aestivum L.) leaves. The biophysical microscale model for gas exchange featured an accurate geometric representation of the actual 2-D leaf tissue microstructure and accounted for diffusive mass exchange of CO2. The resulting gas transport equations were coupled to the biochemical Farquhar-von Caemmerer-Berry model for photosynthesis. The combined model was evaluated using gas exchange and chlorophyll fluorescence measurements on wheat leaves. In general a good agreement between model predictions and measurements was obtained, but a discrepancy was observed for the mesophyll conductance at high CO2 levels and low irradiance levels. This may indicate that some physiological processes related to photosynthesis are not incorporated in the model. The model provided detailed insight into the mechanisms of gas exchange and the effects of changes in ambient CO2 concentration or photon flux density on stomatal and mesophyll conductance. It represents an important step forward to study CO2 diffusion coupled to photosynthesis at the leaf tissue level, taking into account the leaf's actual microstructure. PMID:23144870

  4. Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2.

    Science.gov (United States)

    Rezende, L F C; Arenque, B C; Aidar, S T; Moura, M S B; Von Randow, C; Tourigny, E; Menezes, R S C; Ometto, J P H B

    2016-07-01

    Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

  5. Modelling Energy Systems and International Trade in CO2 Emission Quotas - The Kyoto Protocol and Beyond

    International Nuclear Information System (INIS)

    Persson, Tobias A.

    2002-01-01

    A transformation of the energy system in the 21st century is required if the CO 2 concentration in the atmosphere should be stabilized at a level that would prevent dangerous anthropogenic interference with the climate system. The industrialized countries have emitted most of the anthropogenic CO 2 released to the atmosphere since the beginning of the industrial era and still account for roughly two thirds of global fossil fuel related CO 2 emissions. Industrial country CO 2 emissions on a per capita basis are roughly five to ten times higher than those of developing countries. However, a global atmospheric CO 2 concentration target of 450 ppm, if adopted would require that global average per capita CO 2 emissions by the end of this century have to be comparable to those of developing countries today. The industrialized countries would have to reduce their emissions substantially and the emissions in developing countries could not follow a business-as-usual scenario. The transformation of the energy system and abatement of CO 2 emissions would need to occur in industrialized and developing countries. Energy-economy models have been developed to analyze of international trading in CO 2 emission permits. The thesis consists of three papers. The cost of meeting the Kyoto Protocol is estimated in the first paper. The Kyoto Protocol, which defines quantitative greenhouse gas emission commitments for industrialized countries over the period 2008-2012, is the first international agreement setting quantitative goals for abatement of CO 2 emissions from energy systems. The Protocol allows the creation of systems for trade in emission permits whereby countries exceeding their target levels can remain in compliance by purchasing surplus permits from other developed countries. However, a huge carbon surplus, which has been christened hot air, has been created in Russia and Ukraine since 1990 primarily because of the contraction of their economies. The current Unites States

  6. Equality and CO2 emissions distribution in climate change integrated assessment modelling

    International Nuclear Information System (INIS)

    Cantore, Nicola; Padilla, Emilio

    2010-01-01

    The equity implications of alternative climate policy measures are an essential issue to be considered in the design of future international agreements to tackle global warming. This paper specifically analyses the future path of emissions and income distribution and its determinants in different scenarios. Whereas our analysis is driven by tools which are typically applied in the income distribution literature and which have recently been applied to the analysis of CO 2 emissions distribution, a new methodological approach is that our study is driven by simulations run with the popular regionalised optimal growth climate change model RICE99 over the 1995-2105 period. We find that the architecture of environmental policies, the implementation of flexible mechanisms and income concentration are key determinants of emissions distribution over time. In particular we find a robust positive relationship between measures of inequalities in the distribution of emissions and income and that their magnitude will essentially depend on technological change. (author)

  7. Gravity monitoring of CO2 movement during sequestration: Model studies

    Energy Technology Data Exchange (ETDEWEB)

    Gasperikova, E.; Hoversten, G.M.

    2008-07-15

    We examine the relative merits of gravity measurements as a monitoring tool for geological CO{sub 2} sequestration in three different modeling scenarios. The first is a combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the second is sequestration in a brine formation, and the third is for a coalbed methane formation. EOR/sequestration petroleum reservoirs have relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and CO{sub 2}), whereas brine formations usually have much thicker injection intervals and only two components (brine and CO{sub 2}). Coal formations undergoing methane extraction tend to be thin (3-10 m), but shallow compared to either EOR or brine formations. The injection of CO{sub 2} into the oil reservoir produced a bulk density decrease in the reservoir. The spatial pattern of the change in the vertical component of gravity (G{sub z}) is directly correlated with the net change in reservoir density. Furthermore, time-lapse changes in the borehole G{sub z} clearly identified the vertical section of the reservoir where fluid saturations are changing. The CO{sub 2}-brine front, on the order of 1 km within a 20 m thick brine formation at 1900 m depth, with 30% CO{sub 2} and 70% brine saturations, respectively, produced a -10 Gal surface gravity anomaly. Such anomaly would be detectable in the field. The amount of CO{sub 2} in a coalbed methane test scenario did not produce a large enough surface gravity response; however, we would expect that for an industrial size injection, the surface gravity response would be measurable. Gravity inversions in all three scenarios illustrated that the general position of density changes caused by CO{sub 2} can be recovered, but not the absolute value of the change. Analysis of the spatial resolution and detectability limits shows that gravity measurements could, under certain circumstances, be used as a lower-cost alternative to seismic

  8. Hollow fiber membrane contactors for CO2 capture: modeling and up-scaling to CO2 capture for an 800 MWe coal power station

    NARCIS (Netherlands)

    Kimball, E.; Al-Azki, A.; Gomez, A.; Goetheer, E.L.V.; Booth, N.; Adams, D.; Ferre, D.

    2014-01-01

    A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM) with the more conventional structured packing columns as the absorber in amine-based CO2capture systems for power plants. In order to simulate the operation of industrial scale HFMMsystems, a

  9. Modeling of CO2 Adsorption on Activated Carbon and 13X Zeolite via Vacuum Swing Adsorption

    Science.gov (United States)

    Zarghampoor, M. H.; Mozaffarian, M.; Soleimani, M.; Takht Ravanchi, M.

    2017-06-01

    Due to carbon dioxide role in global warming, low CO2 emission limits have been established in recent years. This has led to a variety of studies on CO2 removal approaches. In this study, a VSA cycle consisting of two packed beds is considered for CO2 removal from flue gas. An atmospheric stream containing 20 CO2 and 80 N2 is fed to the beds at 50°C. Two adsorbents, namely Zeolite 13X and activated carbon were selected to compare their performance. Due to the monolayer adsorption of CO2 and N2 on these adsorbents, the Toth isotherm was used for equilibrium adsorption estimation. A quasi-second order model was considered for the mass transfer rate prediction due to low CO2 concentration. The modeling results showed that the average absolute deviation for equilibrium adsorption capacity prediction was 2, and the CO2 breakthrough time curve was predicted with less than 2.5 deviation. Based on the results, the VSA cycle time for zeolite 13X bed will be 3.5 times of the activated carbon bed. Another advantage of Zeolite 13X is that in each process cycle, 80 of adsorbent will be used, while only 74 of activated carbon in beds is used. The advantage of activated carbon bed is its better regeneration capability, since the activated carbon will be regenerated 5 more than zeolite 13X at a vacuum pressure of 0.02bar.

  10. Fast Atmosphere-Ocean Model Runs with Large Changes in CO2

    Science.gov (United States)

    Russell, Gary L.; Lacis, Andrew A.; Rind, David H.; Colose, Christopher; Opstbaum, Roger F.

    2013-01-01

    How does climate sensitivity vary with the magnitude of climate forcing? This question was investigated with the use of a modified coupled atmosphere-ocean model, whose stability was improved so that the model would accommodate large radiative forcings yet be fast enough to reach rapid equilibrium. Experiments were performed in which atmospheric CO2 was multiplied by powers of 2, from 1/64 to 256 times the 1950 value. From 8 to 32 times, the 1950 CO2, climate sensitivity for doubling CO2 reaches 8 C due to increases in water vapor absorption and cloud top height and to reductions in low level cloud cover. As CO2 amount increases further, sensitivity drops as cloud cover and planetary albedo stabilize. No water vapor-induced runaway greenhouse caused by increased CO2 was found for the range of CO2 examined. With CO2 at or below 1/8 of the 1950 value, runaway sea ice does occur as the planet cascades to a snowball Earth climate with fully ice covered oceans and global mean surface temperatures near 30 C.

  11. Large divergence of satellite and Earth system model estimates of global terrestrial CO2 fertilization

    Science.gov (United States)

    Smith, W. Kolby; Reed, Sasha C.; Cleveland, Cory C.; Ballantyne, Ashley P; Anderegg, William R. L.; Wieder, William R.; Liu, Yi Y; Running, Steven W.

    2015-01-01

    Atmospheric mass balance analyses suggest that terrestrial carbon (C) storage is increasing, partially abating the atmospheric [CO2] growth rate, although the continued strength of this important ecosystem service remains uncertain. Some evidence suggests that these increases will persist owing to positive responses of vegetation growth (net primary productivity; NPP) to rising atmospheric [CO2] (that is, ‘CO2 fertilization’). Here, we present a new satellite-derived global terrestrial NPP data set, which shows a significant increase in NPP from 1982 to 2011. However, comparison against Earth system model (ESM) NPP estimates reveals a significant divergence, with satellite-derived increases (2.8 ± 1.50%) less than half of ESM-derived increases (7.6  ±  1.67%) over the 30-year period. By isolating the CO2 fertilization effect in each NPP time series and comparing it against a synthesis of available free-air CO2 enrichment data, we provide evidence that much of the discrepancy may be due to an over-sensitivity of ESMs to atmospheric [CO2], potentially reflecting an under-representation of climatic feedbacks and/or a lack of representation of nutrient constraints. Our understanding of CO2 fertilization effects on NPP needs rapid improvement to enable more accurate projections of future C cycle–climate feedbacks; we contend that better integration of modelling, satellite and experimental approaches offers a promising way forward.

  12. A Regional CO2 Observing System Simulation Experiment for the ASCENDS Satellite Mission

    Science.gov (United States)

    Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Baker, D. F.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Zaccheo, T. S.

    2014-01-01

    Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions) generated by the WRF-STILT Lagrangian transport model in a regional Bayesian synthesis inversion. The regional Lagrangian framework is well suited to make use of ASCENDS observations to constrain fluxes at high resolution, in this case at 1 degree latitude x 1 degree longitude and weekly for North America. We consider random measurement errors only, modeled as a function of mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the 1 degree x 1 degree, weekly scale, the largest uncertainty reductions, on the order of 50 percent, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 micron candidate wavelength than for a 2.05 micron wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada). Uncertainty reductions at the annual, biome scale range from 40 percent to 75 percent across our four instrument design cases, and from 65 percent to 85 percent for the continent as a whole. Our uncertainty

  13. Methane and CO2 Adsorption and Transport in Carbon-based Systems from Experiments and Molecular Simulation

    Science.gov (United States)

    Wilcox, Jennifer; Firouzi, Mahnaz; Rupp, Erik; Haghapanah, Reza; Wang, Beibei

    2013-04-01

    Carbon capture and sequestration is one strategy that could potentially mitigate gigatons of CO2 emissions per year; however, technical obstacles have thus far hindered wide-scale deployment of this strategy. To design efficient and reliable strategies for either carbon capture or sequestration at the full-scale, one needs to understand the chemical and physical properties of CO2 and its interaction with its local surroundings at the molecular-scale. To investigate the chemical and physical properties of CO2 and its local surroundings at the molecular-scale, surface characterization studies are carried out alongside theoretical model efforts. Experimental investigation of CO2 interactions with organic-based porous materials ranging in complexity from functionalized graphene and activated carbon to various-rank coal and gas shale samples to create a set of realistic models that take into account both surface and pore heterogeneity. Integration of theory and experiments takes place to allow for the relevant physics at the molecular-level to be revealed. Determining adsorption and transport phenomena of CO2 (and mixtures, including H2O, and CH4) within the model pore systems can be used to understand the complex pore matrices of carbon-based sorbents, coal, and the organic components of gas shale that are crucial to determining their carbon capture or sequestration potential. Non-equilibrium molecular dynamics (NEMD) simulations of pure carbon dioxide, methane, helium and their mixtures have been carried out in carbon slit pores to investigate gas slippage and Klinkenberg effects in the organic matrices of coal and gas shale rocks. NEMD techniques are ideally suited for the experimental situation in which an external driving force, such as a chemical potential or pressure gradient, are applied on the system. Simulations have been conducted to determine the effect of pore size and exposure to an external potential on the velocity profile and slip-stick boundary

  14. Modeling radical edge-site reactions of biochar in CO2/water solution under ultrasonic treatment

    Science.gov (United States)

    Zubatiuk, Tetiana; Sajjadi, Baharak; Hill, Glake; Leszczynska, Danuta; Chen, Wei-Yin; Leszczynski, Jerzy

    2017-12-01

    We report results of theoretical evaluation of the mechanisms of possible radical reactions on the edge-site of biochar with CO2,SUP>·-, OH ˙ , and H ˙ in irradiated aqueous solution. The computational studies were performed for model poly aromatic systems. Obtained mechanisms reflect one of the routes of the oxygen loss accompanied by increase of hydrogen content, as observed in photochemical experiment. The reaction of CO2·- with the edge site of biochar mainly leads to reduced rather than oxidized products. The mechanism of CO2 capturing is mapped by different routes of one-electron reduction and radical addition to the aromatic ring.

  15. Analysis on influence factors of China's CO2 emissions based on Path-STIRPAT model

    International Nuclear Information System (INIS)

    Li Huanan; Mu Hailin; Zhang Ming; Li Nan

    2011-01-01

    With the intensification of global warming and continued growth in energy consumption, China is facing increasing pressure to cut its CO 2 (carbon dioxide) emissions down. This paper discusses the driving forces influencing China's CO 2 emissions based on Path-STIRPAT model-a method combining Path analysis with STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The analysis shows that GDP per capita (A), industrial structure (IS), population (P), urbanization level (R) and technology level (T) are the main factors influencing China's CO 2 emissions, which exert an influence interactively and collaboratively. The sequence of the size of factors' direct influence on China's CO 2 emission is A>T>P>R>IS, while that of factors' total influence is A>R>P>T>IS. One percent increase in A, IS, P, R and T leads to 0.44, 1.58, 1.31, 1.12 and -1.09 percentage change in CO 2 emission totally, where their direct contribution is 0.45, 0.07, 0.63, 0.08, 0.92, respectively. Improving T is the most important way for CO 2 reduction in China. - Highlights: → We analyze the driving forces influencing China's CO 2 emissions. → Five macro factors like per capita GDP are the main influencing factors. → These factors exert an influence interactively and collaboratively. → Different factors' direct and total influence on China's CO 2 emission is different. → Improving technology level is the most important way for CO 2 reduction in China.

  16. Research on CO2 ejector component efficiencies by experiment measurement and distributed-parameter modeling

    International Nuclear Information System (INIS)

    Zheng, Lixing; Deng, Jianqiang

    2017-01-01

    Highlights: • The ejector distributed-parameter model is developed to study ejector efficiencies. • Feasible component and total efficiency correlations of ejector are established. • New efficiency correlations are applied to obtain dynamic characteristics of EERC. • More suitable fixed efficiency value can be determined by the proposed correlations. - Abstract: In this study we combine the experimental measurement data and the theoretical model of ejector to determine CO 2 ejector component efficiencies including the motive nozzle, suction chamber, mixing section, diffuser as well as the total ejector efficiency. The ejector is modeled utilizing the distributed-parameter method, and the flow passage is divided into a number of elements and the governing equations are formulated based on the differential equation of mass, momentum and energy conservation. The efficiencies of ejector are investigated under different ejector geometric parameters and operational conditions, and the corresponding empirical correlations are established. Moreover, the correlations are incorporated into a transient model of transcritical CO 2 ejector expansion refrigeration cycle (EERC) and the dynamic simulations is performed based on variable component efficiencies and fixed values. The motive nozzle, suction chamber, mixing section and diffuser efficiencies vary from 0.74 to 0.89, 0.86 to 0.96, 0.73 to 0.9 and 0.75 to 0.95 under the studied conditions, respectively. The response diversities of suction flow pressure and discharge pressure are obvious between the variable efficiencies and fixed efficiencies referring to the previous studies, while when the fixed value is determined by the presented correlations, their response differences are basically the same.

  17. A Comparative Data-Based Modeling Study on Respiratory CO2 Gas Exchange during Mechanical Ventilation

    Directory of Open Access Journals (Sweden)

    Chang-Sei eKim

    2016-02-01

    Full Text Available The goal of this study is to derive a minimally complex but credible model of respiratory CO2 gas exchange that may be used in systematic design and pilot testing of closed-loop end-tidal CO2 controllers in mechanical ventilation. We first derived a candidate model that captures the essential mechanisms involved in the respiratory CO2 gas exchange process. Then, we simplified the candidate model to derive two lower-order candidate models. We compared these candidate models for predictive capability and reliability using experimental data collected from 25 pediatric subjects undergoing dynamically varying mechanical ventilation during surgical procedures. A two-compartment model equipped with transport delay to account for CO2 delivery between the lungs and the tissues showed modest but statistically significant improvement in predictive capability over the same model without transport delay. Aggregating the lungs and the tissues into a single compartment further degraded the predictive fidelity of the model. In addition, the model equipped with transport delay demonstrated superior reliability to the one without transport delay. Further, the respiratory parameters derived from the model equipped with transport delay, but not the one without transport delay, were physiologically plausible. The results suggest that gas transport between the lungs and the tissues must be taken into account to accurately reproduce the respiratory CO2 gas exchange process under conditions of wide-ranging and dynamically varying mechanical ventilation conditions.

  18. Analyzing impact factors of CO2 emissions using the STIRPAT model

    International Nuclear Information System (INIS)

    Fan Ying; Liu Lancui; Wu Gang; Wei Yiming

    2006-01-01

    Using the STIRPAT model, this paper analyzes the impact of population, affluence and technology on the total CO 2 emissions of countries at different income levels over the period 1975-2000. Our main results show at the global level that economic growth has the greatest impact on CO 2 emissions, and the proportion of the population between ages 15 and 64 has the least impact. The proportion of the population between 15 and 64 has a negative impact on the total CO 2 emissions of countries at the high income level, but the impact is positive at other income levels. This may illustrate the importance of the 'B' in the 'I = PABT'; that is to say that different behavior fashions can greatly influence environmental change. For low-income countries, the impact of GDP per capita on total CO 2 emissions is very great, and the impact of energy intensity in upper-middle income countries is very great. The impact of these factors on the total CO 2 emissions of countries at the high income level is relatively great. Therefore, these empirical results indicate that the impact of population, affluence and technology on CO 2 emissions varies at different levels of development. Thus, policy-makers should consider these matters fully when they construct their long-term strategies for CO 2 abatement

  19. Investigating Mars South Residual CO2 Cap with a Global Climate Model

    Science.gov (United States)

    Kahre, M. A.; Dequaire, J.; Hollingsworth, J. L.; Haberle, R. M.

    2016-01-01

    The CO2 cycle is one of the three controlling climate cycles on Mars. One aspect of the CO2 cycle that is not yet fully understood is the existence of a residual CO2 ice cap that is offset from the south pole. Previous investigations suggest that the atmosphere may control the placement of the south residual cap (e.g., Colaprete et al., 2005). These investigations show that topographically forced stationary eddies in the south during southern hemisphere winter produce colder atmospheric temperatures and increased CO2 snowfall over the hemisphere where the residual cap resides. Since precipitated CO2 ice produces higher surface albedos than directly deposited CO2 ice, it is plausible that CO2 snowfall resulting from the zonally asymmetric atmospheric circulation produces surface ice albedos high enough to maintain a residual cap only in one hemisphere. The goal of the current work is to further evaluate Colaprete et al.'s hypothesis by investigating model-predicted seasonally varying snowfall patterns in the southern polar region and the atmospheric circulation components that control them.

  20. Mass transport modelling for the electroreduction of CO2 on Cu nanowires

    Science.gov (United States)

    Raciti, David; Mao, Mark; Wang, Chao

    2018-01-01

    Mass transport plays an important role in CO2 reduction electrocatalysis. Albeit being more pronounced on nanostructured electrodes, the studies of mass transport for CO2 reduction have yet been limited to planar electrodes. We report here the development of a mass transport model for the electroreduction of CO2 on Cu nanowire electrodes. Fed with the experimental data from electrocatalytic studies, the local concentrations of CO2, {{{{HCO}}}3}-,{{{{CO}}}3}2- and OH- on the nanostructured electrodes are calculated by solving the diffusion equations with spatially distributed electrochemical reaction terms incorporated. The mass transport effects on the catalytic activity and selectivity of the Cu nanowire electrocatalysts are thus discussed by using the local pH as the descriptor. The established correlations between the electrocatalytic performance and the local pH shows that, the latter does not only determine the acid-base reaction equilibrium, but also regulates the mass transport and reaction kinetics. Based on these findings, the optimal range of local pH for CO2 reduction is discussed in terms of a fine balance among the suppression of hydrogen evolution, improvement of C2 product selectivity and limitation of CO2 supply. Our work highlights the importance of understanding the mass transport effects in interpretation of CO2 reduction electrocatalysis on high-surface-area catalysts.

  1. Estimation of CO2 emission from water treatment plant--model development and application.

    Science.gov (United States)

    Kyung, Daeseung; Kim, Dongwook; Park, Nosuk; Lee, Woojin

    2013-12-15

    A comprehensive mathematical model developed for this study was used to compare estimates of on-site and off-site CO2 emissions, from conventional and advanced water treatment plants (WTPs). When 200,000 m(3) of raw water at 10 NTU (Nepthelometric Turbidity Unit) was treated by a conventional WTP to 0.1 NTU using aluminum sulfate as a coagulant, the total CO2 emissions were estimated to be 790 ± 228 (on-site) and 69,596 ± 3950 (off-site) kg CO2e/d. The emissions from an advanced WTP containing micro-filtration (MF) membrane and ozone disinfection processes; treating the same raw water to 0.005 NTU, were estimated to be 395 ± 115 (on-site) and 38,197 ± 2922 (off-site) kg CO2e/d. The on-site CO2 emissions from the advanced WTP were half that from the conventional WTP due to much lower use of coagulant. On the other hand, off-site CO2 emissions due to consumption of electricity were 2.14 times higher for the advanced WTP, due to the demands for operation of the MF membrane and ozone disinfection processes. However, the lower use of chemicals in the advanced WTP decreased off-site CO2 emissions related to chemical production and transportation. Overall, total CO2 emissions from the conventional WTP were 1.82 times higher than that from the advanced WTP. A sensitivity analysis was performed for the advanced WTP to suggest tactics for simultaneously reducing CO2 emissions further and enhancing water quality. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Cheminformatics Modeling of Amine Solutions for Assessing their CO2 Absorption Properties.

    Science.gov (United States)

    Kuenemann, Melaine A; Fourches, Denis

    2017-07-01

    As stricter regulations on CO 2 emissions are adopted worldwide, identifying efficient chemical processes to capture and recycle CO 2 is of critical importance for industry. The most common process known as amine scrubbing suffers from the lack of available amine solutions capable of capturing CO 2 efficiently. Tertiary amines characterized by low heats of reaction are considered good candidates but their absorption properties can significantly differ from one analogue to another despite high structural similarity. Herein, after collecting and curating experimental data from the literature, we have built a modeling set of 41 amine structures with their absorption properties. Then we analyzed their chemical composition using molecular descriptors and non-supervised clustering. Furthermore, we developed a series of quantitative structure-property relationships (QSPR) to assess amines' CO 2 absorption properties from their structural characteristics. These models afforded reasonable prediction performances (e. g., Q 2 LOO =0.63 for CO 2 absorption amount) even though they are solely based on 2D chemical descriptors and individual machine learning techniques (random forest and neural network). Overall, we believe the chemical analysis and the series of QSPR models presented in this proof-of-concept study represent new knowledge and innovative tools that could be very useful for screening and prioritizing hypothetical amines to be synthesized and tested experimentally for their CO 2 absorption properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Lattice-Boltzmann modeling of experimental fluid displacement patterns, interfacial area and capillary trapped CO2

    Science.gov (United States)

    Porter, M. L.; Kang, Q.; Tarimala, S.; Abdel-Fattah, A.; Backhaus, S.; Carey, J. W.

    2010-12-01

    Successful sequestration of CO2 into deep saline aquifers presents an enormous challenge that requires fundamental understanding of reactive-multiphase flow and transport across many temporal and spatial scales. Of critical importance is accurately predicting the efficiency of CO2 trapping mechanisms. At the pore scale (e.g., microns to millimeters) the interfacial area between CO2 and brine, as well as CO2 and the solid phase, directly influences the amount of CO2 trapped due to capillary forces, dissolution and mineral precipitation. In this work, we model immiscible displacement micromodel experiments using the lattice-Boltzmann (LB) method. We focus on quantifying interfacial area as a function of capillary numbers and viscosity ratios typically encountered in CO2 sequestration operations. We show that the LB model adequately predicts the steady-state experimental flow patterns and interfacial area measurements. Based on the steady-state agreement, we use the LB model to investigate interfacial dynamics (e.g., fluid-fluid interfacial velocity and the rate of production of fluid-fluid interfacial area). In addition, we quantify the amount of interfacial area and the interfacial dynamics associated with the capillary trapped nonwetting phase. This is expected to be important for predicting the amount of nonwetting phase subsequently trapped due to dissolution and mineral precipitation.

  4. Elementary reaction modeling of reversible CO/CO2 electrochemical conversion on patterned nickel electrodes

    Science.gov (United States)

    Luo, Yu; Shi, Yixiang; Li, Wenying; Cai, Ningsheng

    2018-03-01

    CO/CO2 are the major gas reactant/product in the fuel electrode of reversible solid oxide cells (RSOC). This study proposes a two-charge-transfer-step mechanism to describe the reaction and transfer processes of CO-CO2 electrochemical conversion on a patterned Ni electrode of RSOC. An elementary reaction model is developed to couple two charge transfer reactions, C(Ni)+O2-(YSZ) ↔ CO(Ni)+(YSZ) +2e- and CO(Ni)+O2-(YSZ) ↔ CO2(Ni)+(YSZ)+2e-, with adsorption/desorption, surface chemical reactions and surface diffusion. This model well validates in both solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes by the experimental data from a patterned Ni electrode with 10 μm stripe width at different pCO (0-0.25 atm), pCO2 (0-0.35 atm) and operating temperature (600-700 °C). This model indicates SOEC mode is dominated by charge transfer step C(Ni)+O2-(YSZ)↔CO(Ni)+(YSZ) +2e-, while SOFC mode by CO(Ni)+ O2-(YSZ)↔CO2(Ni)+(YSZ)+2e- on the patterned Ni electrode. The sensitivity analysis shows charge transfer step is the major rate-determining step for RSOC, besides, surface diffusion of CO and CO2 as well as CO2 adsorption also plays a significant role in the electrochemical reaction of SOEC while surface diffusion of CO and CO2 desorption could be co-limiting in SOFC.

  5. A multi-model approach to monitor emissions of CO2 and CO from an urban-industrial complex

    Science.gov (United States)

    Super, Ingrid; Denier van der Gon, Hugo A. C.; van der Molen, Michiel K.; Sterk, Hendrika A. M.; Hensen, Arjan; Peters, Wouter

    2017-11-01

    Monitoring urban-industrial emissions is often challenging because observations are scarce and regional atmospheric transport models are too coarse to represent the high spatiotemporal variability in the resulting concentrations. In this paper we apply a new combination of an Eulerian model (Weather Research and Forecast, WRF, with chemistry) and a Gaussian plume model (Operational Priority Substances - OPS). The modelled mixing ratios are compared to observed CO2 and CO mole fractions at four sites along a transect from an urban-industrial complex (Rotterdam, the Netherlands) towards rural conditions for October-December 2014. Urban plumes are well-mixed at our semi-urban location, making this location suited for an integrated emission estimate over the whole study area. The signals at our urban measurement site (with average enhancements of 11 ppm CO2 and 40 ppb CO over the baseline) are highly variable due to the presence of distinct source areas dominated by road traffic/residential heating emissions or industrial activities. This causes different emission signatures that are translated into a large variability in observed ΔCO : ΔCO2 ratios, which can be used to identify dominant source types. We find that WRF-Chem is able to represent synoptic variability in CO2 and CO (e.g. the median CO2 mixing ratio is 9.7 ppm, observed, against 8.8 ppm, modelled), but it fails to reproduce the hourly variability of daytime urban plumes at the urban site (R2 up to 0.05). For the urban site, adding a plume model to the model framework is beneficial to adequately represent plume transport especially from stack emissions. The explained variance in hourly, daytime CO2 enhancements from point source emissions increases from 30 % with WRF-Chem to 52 % with WRF-Chem in combination with the most detailed OPS simulation. The simulated variability in ΔCO :  ΔCO2 ratios decreases drastically from 1.5 to 0.6 ppb ppm-1, which agrees better with the observed standard

  6. A possible new role for atmospheric 13CO2 in global models

    NARCIS (Netherlands)

    Miller, J. B.; Ballantyne, A.; Berry, J. A.; Peters, W.; Still, C.; Tans, P.; White, J.

    2008-01-01

    The promise of utilizing large-scale atmospheric δ13CO2 measurements to understand terrestrial processes has not been fully realized. Here, we will present recent progress in the use of measurements and simulations of atmospheric δ13C to better understand the signals of the biosphere contained

  7. Geophysical and Geochemical Aspects of Pressure and CO2 Saturation Modeling due to Migration of Fluids into the Above Zone Monitoring Interval of a Geologic Carbon Storage Site

    Science.gov (United States)

    Zhang, L.; Namhata, A.; Dilmore, R. M.; Bromhal, G. S.

    2016-12-01

    An increasing emphasis on the industrial scale implementation of CO2 storage into geological formations has led to the development of whole-system models to evaluate performance of candidate geologic storage sites, and the environmental risk associated with them. The components of that engineered geologic system include the storage reservoir, primary and secondary seals, and the overlying formations above primary and secondary seals (above-zone monitoring interval, AZMI). Leakage of CO2 and brine through the seal to the AZMI may occur due to the presence of natural or induced fractures in the seal. In this work, an AZMI model that simulates pressure and CO2 saturation responses through time to migration of fluids (here, CO2 and brine) from the primary seal to the AZMI is developed. A hypothetical case is examined wherein CO2 is injected into a storage reservoir for 30 years and a heterogeneous primary seal exists above the reservoir with some permeable zones. The total simulation period is 200 years (30 years of CO2 injection period and 170 years of post CO2 injection period). Key geophysical parameters such as permeability of the AZMI, thickness of the AZMI and porosity of the AZMI have significant impact on pressure evolution in the AZMI. arbitrary Polynomial Chaos (aPC) Expansion analysis shows that permeability of the AZMI has the most significant impact on pressure build up in the AZMI above the injection well at t=200 years, followed by thickness of the AZMI and porosity of the AZMI. Geochemical reactions have no impact on pressure and CO2 saturation evolution in the AZMI during the CO2 injection period. After the CO2 injection stops, precipitation of secondary minerals (e.g., amorphous silica and kaolinite) at the CO2 plume/brine interface in the AZMI formation may cause permeability reduction of the AZMI, which restrains horizontal migration of CO2 in the AZMI.

  8. North American CO2 fluxes for 2007-2015 from NOAA's CarbonTracker-Lagrange Regional Inverse Modeling Framework

    Science.gov (United States)

    Andrews, A. E.; Hu, L.; Thoning, K. W.; Nehrkorn, T.; Mountain, M. E.; Jacobson, A. R.; Michalak, A.; Dlugokencky, E. J.; Sweeney, C.; Worthy, D. E. J.; Miller, J. B.; Fischer, M. L.; Biraud, S.; van der Velde, I. R.; Basu, S.; Tans, P. P.

    2017-12-01

    CarbonTracker-Lagrange (CT-L) is a new high-resolution regional inverse modeling system for improved estimation of North American CO2 fluxes. CT-L uses footprints from the Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by high-resolution (10 to 30 km) meteorological fields from the Weather Research and Forecasting (WRF) model. We performed a suite of synthetic-data experiments to evaluate a variety of inversion configurations, including (1) solving for scaling factors to an a priori flux versus additive corrections, (2) solving for fluxes at 3-hrly resolution versus at coarser temporal resolution, (3) solving for fluxes at 1o × 1o resolution versus at large eco-regional scales. Our framework explicitly and objectively solves for the optimal solution with a full error covariance matrix with maximum likelihood estimation, thereby enabling rigorous uncertainty estimates for the derived fluxes. In the synthetic-data inversions, we find that solving for weekly scaling factors of a priori Net Ecosystem Exchange (NEE) at 1o × 1o resolution with optimization of diurnal cycles of CO2 fluxes yields faithful retrieval of the specified "true" fluxes as those solved at 3-hrly resolution. In contrast, a scheme that does not allow for optimization of diurnal cycles of CO2 fluxes suffered from larger aggregation errors. We then applied the optimal inversion setup to estimate North American fluxes for 2007-2015 using real atmospheric CO2 observations, multiple prior estimates of NEE, and multiple boundary values estimated from the NOAA's global Eulerian CarbonTracker (CarbonTracker) and from an empirical approach. Our derived North American land CO2 fluxes show larger seasonal amplitude than those estimated from the CarbonTracker, removing seasonal biases in the CarbonTracker's simulated CO2 mole fractions. Independent evaluations using in-situ CO2 eddy covariance flux measurements and independent aircraft profiles also suggest an improved estimation on North

  9. Modeling experimental stable isotope results from CO2 adsorption and diffusion experiments

    Science.gov (United States)

    Larson, T. E.

    2012-12-01

    steadily increased and became constant after two pore volumes of CO2 flushed through the column. Carbon and oxygen isotope values of the front of the peak (first pore volume) are 2‰ and 5‰ lower than the injected CO2 values, respectively. These results are fit very well using a mass transfer model that only includes binary diffusion between CO2 and helium that account for isotope substitution in the reduced mass coefficient. In contrast to these diffusion-dominated systems, CO2 break through curves from the illite packed column show strong adsorption effects that include a +180‰ increase in the carbon isotope ratio at the front of the peak followed by a 20‰ decrease. Up to 20 pore volumes of CO2 were flushed through the column before the carbon and oxygen isotope values stabilized to their starting values. These adsorption effects cannot be modeled using mass isotope effects alone, and instead must include additional parameters such as volume effects. These results demonstrate the importance of understanding the isotopic effects of CO2 in different substrates, and potentially offers a tracer tool that can be used to quantify surface area, transport distance, and surface reactivity of CO2. Additional applications may include more affectively determining transfer rates of CO2 across low permeability zones.

  10. Simulating soil N2O emissions and heterotrophic CO2 respiration in arabe systems using FASSET and MoBiLE-DNDC

    DEFF Research Database (Denmark)

    Chirinda, Ngonidzashe; Kracher, Daniele; Lægdsmand, Mette

    2011-01-01

    Modelling of soil emissions of nitrous oxide (N2O) and carbon dioxide (CO2) is complicated by complex interactions between processes and factors influencing their production, consumption and transport. In this study N2O emissions and heterotrophic CO2 respiration were simulated from soils under...... winter wheat grown in three different organic and one inorganic fertilizer-based cropping system using two different models, i.e., MoBiLE-DNDC and FASSET. The two models were generally capable of simulating most seasonal trends of measured soil heterotrophic CO2 respiration and N2O emissions. Annual soil...... heterotrophic CO2 respiration was underestimated by both models in all systems (about 10–30% by FASSET and 10–40% by MoBiLE-DNDC). Both models overestimated annual N2O emissions in all systems (about 10–580% by FASSET and 20–50% by MoBiLE-DNDC). In addition, both models had some problems in simulating soil...

  11. Decarbonizing the European electricity sector. Modeling and policy analysis for electricity and CO2 infrastructure networks

    International Nuclear Information System (INIS)

    Oei, Pao-Yu Charly Robin

    2016-01-01

    This dissertation uses three models to analyze different decarbonization strategies for combating global climate change: The cost minimizing mixed-integer model CCTS-Mod examines the economics of Carbon Capture, Transport, and Storage (CCTS) for the electricity and industry sector; the welfare maximizing quadratically constrained model ELMOD focuses on different trajectories for renewable energy sources (RES) and transmission grid expansions; and the equilibrium model ELCO combines the insights of the individual sectors to a combined CCTS and electricity investment and dispatch model. Modeling results show that an investment in CCTS is beneficial for the iron and steel sector once the CO 2 certificate price exceeds 50 Euros/t CO 2 . The threshold is 75 Euros/t CO 2 for the cement industry and 100 Euros/t CO 2 for the electricity sector. Additional revenues from using CO 2 for enhanced oil recovery (CO 2 -EOR) lead to an earlier adoption of CCTS in the North Sea region. The lack of economies of scale results in increasing CO 2 storage costs of more than 30%, while transport costs even double. Research from the last years, however, indicates that CCTS is unlikely to play an important role in decarbonizing the electricity sector. The identified reasons for this are incumbents' resistance to structural change, wrong technology choices, over-optimistic cost estimates, a premature focus on energy projects instead of industry, and the underestimation of transport and storage issues. Keeping global temperature rise below 2 C therefore implies the phase-out of fossilfueled power plants and, in particular, of CO 2 -intensive coal power plants. The low CO 2 price established by the European Emissions Trading Scheme is insufficient to induce a fuel switch in the medium term. Therefore, supplementary national measures are necessary to reduce coal-based power generation; i.a. feed-in tariffs for RES, minimum CO 2 prices, or emissions performance standards. Analyses for

  12. Industrial point source CO2 emission strength estimation with aircraft measurements and dispersion modelling.

    Science.gov (United States)

    Carotenuto, Federico; Gualtieri, Giovanni; Miglietta, Franco; Riccio, Angelo; Toscano, Piero; Wohlfahrt, Georg; Gioli, Beniamino

    2018-02-22

    CO 2 remains the greenhouse gas that contributes most to anthropogenic global warming, and the evaluation of its emissions is of major interest to both research and regulatory purposes. Emission inventories generally provide quite reliable estimates of CO 2 emissions. However, because of intrinsic uncertainties associated with these estimates, it is of great importance to validate emission inventories against independent estimates. This paper describes an integrated approach combining aircraft measurements and a puff dispersion modelling framework by considering a CO 2 industrial point source, located in Biganos, France. CO 2 density measurements were obtained by applying the mass balance method, while CO 2 emission estimates were derived by implementing the CALMET/CALPUFF model chain. For the latter, three meteorological initializations were used: (i) WRF-modelled outputs initialized by ECMWF reanalyses; (ii) WRF-modelled outputs initialized by CFSR reanalyses and (iii) local in situ observations. Governmental inventorial data were used as reference for all applications. The strengths and weaknesses of the different approaches and how they affect emission estimation uncertainty were investigated. The mass balance based on aircraft measurements was quite succesful in capturing the point source emission strength (at worst with a 16% bias), while the accuracy of the dispersion modelling, markedly when using ECMWF initialization through the WRF model, was only slightly lower (estimation with an 18% bias). The analysis will help in highlighting some methodological best practices that can be used as guidelines for future experiments.

  13. Prediction of heat capacity of amine solutions using artificial neural network and thermodynamic models for CO2 capture processes

    Science.gov (United States)

    Afkhamipour, Morteza; Mofarahi, Masoud; Borhani, Tohid Nejad Ghaffar; Zanganeh, Masoud

    2018-03-01

    In this study, artificial neural network (ANN) and thermodynamic models were developed for prediction of the heat capacity ( C P ) of amine-based solvents. For ANN model, independent variables such as concentration, temperature, molecular weight and CO2 loading of amine were selected as the inputs of the model. The significance of the input variables of the ANN model on the C P values was investigated statistically by analyzing of correlation matrix. A thermodynamic model based on the Redlich-Kister equation was used to correlate the excess molar heat capacity ({C}_P^E) data as function of temperature. In addition, the effects of temperature and CO2 loading at different concentrations of conventional amines on the C P values were investigated. Both models were validated against experimental data and very good results were obtained between two mentioned models and experimental data of C P collected from various literatures. The AARD between ANN model results and experimental data of C P for 47 systems of amine-based solvents studied was 4.3%. For conventional amines, the AARD for ANN model and thermodynamic model in comparison with experimental data were 0.59% and 0.57%, respectively. The results showed that both ANN and Redlich-Kister models can be used as a practical tool for simulation and designing of CO2 removal processes by using amine solutions.

  14. Numerical Simulation and Optimization of Enhanced Oil Recovery by the In Situ Generated CO2 Huff-n-Puff Process with Compound Surfactant

    Directory of Open Access Journals (Sweden)

    Yong Tang

    2016-01-01

    Full Text Available This paper presents the numerical investigation and optimization of the operating parameters of the in situ generated CO2 Huff-n-Puff method with compound surfactant on the performance of enhanced oil recovery. First, we conducted experiments of in situ generated CO2 and surfactant flooding. Next, we constructed a single-well radial 3D numerical model using a thermal recovery chemical flooding simulator to simulate the process of CO2 Huff-n-Puff. The activation energy and reaction enthalpy were calculated based on the reaction kinetics and thermodynamic models. The interpolation parameters were determined through history matching a series of surfactant core flooding results with the simulation model. The effect of compound surfactant on the Huff-n-Puff CO2 process was demonstrated via a series of sensitivity studies to quantify the effects of a number of operation parameters including the injection volume and mole concentration of the reagent, the injection rate, the well shut-in time, and the oil withdrawal rate. Based on the daily production rate during the period of Huff-n-Puff, a desirable agreement was shown between the field applications and simulated results.

  15. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)

    Two popular methods to analyse the operation of CW CO 2 lasers use the temperature model and the rate equation model. Among the two, the latter model directly calculates the population densities in the various vibrational levels connected with the lasing action, and provides a clearer illustration of the processes involved ...

  16. Optimal plant nitrogen use improves model representation of vegetation response to elevated CO2

    Science.gov (United States)

    Caldararu, Silvia; Kern, Melanie; Engel, Jan; Zaehle, Sönke

    2017-04-01

    Existing global vegetation models often cannot accurately represent observed ecosystem behaviour under transient conditions such as elevated atmospheric CO2, a problem that can be attributed to an inflexibility in model representation of plant responses. Plant optimality concepts have been proposed as a solution to this problem as they offer a way to represent plastic plant responses in complex models. Here we present a novel, next generation vegetation model which includes optimal nitrogen allocation to and within the canopy as well as optimal biomass allocation between above- and belowground components in response to nutrient and water availability. The underlying hypothesis is that plants adjust their use of nitrogen in response to environmental conditions and nutrient availability in order to maximise biomass growth. We show that for two FACE (Free Air CO2 enrichment) experiments, the Duke forest and Oak Ridge forest sites, the model can better predict vegetation responses over the duration of the experiment when optimal processes are included. Specifically, under elevated CO2 conditions, the model predicts a lower optimal leaf N concentration as well as increased biomass allocation to fine roots, which, combined with a redistribution of leaf N between the Rubisco and chlorophyll components, leads to a continued NPP response under high CO2, where models with a fixed canopy stoichiometry predict a quick onset of N limitation.Existing global vegetation models often cannot accurately represent observed ecosystem behaviour under transient conditions such as elevated atmospheric CO2, a problem that can be attributed to an inflexibility in model representation of plant responses. Plant optimality concepts have been proposed as a solution to this problem as they offer a way to represent plastic plant responses in complex models. Here we present a novel, next generation vegetation model which includes optimal nitrogen allocation to and within the canopy as well as

  17. New Model of the night-time CO2 4.3 µm emissions in the mesosphere/lower thermosphere

    Science.gov (United States)

    Panka, P.; Kutepov, A. A.; Kalogerakis, K. S.; Janches, D.; Russell, J. M., III; Rezac, L.; Feofilov, A.; Mlynczak, M. G.; Yiğit, E.

    2016-12-01

    We present a new non-LTE model of the night-time CO2 4.3 µm emissions in the MLT which accounts for various mechanisms of the non-thermal excitation of CO2 molecules. We pay specific attention to the transfer of vibrational energy of OH(v), produced in the chemical reaction H + O3, to the CO2(v3) vibrational mode. Two energy transfer channels are studied: 1) the "direct" mechanism, OH(v)→N2(v)→CO2(v3)→4.3 µm, suggested by Kumer et al, [1978], and 2) the new "indirect" mechanism, OH(v)→O(1D)→N2(v)→CO2(ν3)→4.3 µm, recently suggested by Sharma et al. [2015]. We show that for various seasonal scenarios above 75 km, the "direct" mechanism alone under-predicts the observed radiance between 30-70%, from 60°S-80°N. However, considering both the "direct" and "indirect" mechanism brings differences between simulated and measured nighttime SABER 4.3 µm limb radiances down to ±10% from 75-85 km and ±20% from 85-110km for the same region. These results suggest that the important mechanism of the nighttime 4.3 µm emission generation, which was missing in previous models [Lopez-Puertas and Taylor, 2001, Lopez-Puertas et al, 2004], has finally been found. This is an important step towards developing the algorithm suitable for retrieving CO2 densities in the MLT from nighttime limb radiances obtained by SABER, which has been taking continuous measurements for the past 15 years.

  18. Modeling and optimal design of CO2 Direct Air Capture systems in large arrays

    Science.gov (United States)

    Sadri Irani, Samaneh; Luzzatto-Fegiz, Paolo

    2017-11-01

    As noted by the 2014 IPCC report, while the rise in atmospheric CO2 would be slowed by emissions reductions, removing atmospheric CO2 is an important part of possible paths to climate stabilization. Direct Air Capture of CO2 with chemicals (DAC) is one of several proposed carbon capture technologies. There is an ongoing debate on whether DAC is an economically viable approach to alleviate climate change. In addition, like all air capture strategies, DAC is strongly constrained by the net-carbon problem, namely the need to control CO2 emissions associated with the capture process (for example, if DAC not powered by renewables). Research to date has focused on the chemistry and economics of individual DAC devices. However, the fluid mechanics of their large-scale deployment has not been examined in the literature, to the best of our knowledge. In this presentation, we develop a model for flow through an array of DAC devices, varying their lateral extent and their separation. We build on a recent theory of canopy flows, introducing terms for CO2 entrainment into the array boundary layer, and transport into the farm. In addition, we examine the possibility of driving flow passively by wind, thereby reducing energy consumption. The optimal operational design is established considering the total cost, drag force, energy consumption and total CO2 capture.

  19. CO2 adsorption on carbon models of organic constituents of gas shale and coal.

    Science.gov (United States)

    Liu, Yangyang; Wilcox, Jennifer

    2011-01-15

    Imperfections of the organic matrix in coal and gas shales are modeled using defective and defect-free graphene surfaces to represent the structural heterogeneity and related chemical nature of these complex systems. Based upon previous experimental investigations that have validated the stability and existence of defect sites in graphene, plane-wave electronic density functional theory (DFT) calculations have been performed to investigate the mechanisms of CO(2) adsorption. The interactions of CO(2) with different surfaces have been compared, and the physisorption energy of CO(2) on the defective graphene adsorption site with one carbon atom missing (monovacancy) is approximately 4 times as strong as that on a perfect defect-free graphene surface, specifically, with a physisorption energy of ∼210 meV on the monovacancy site compared to ∼50 meV on a perfect graphene surface. The energy associated with the chemisorption of CO(2) on the monovacancy site is substantially stronger at ∼1.72 eV. Bader charge, density of states, and vibrational frequency estimations were also carried out and the results indicate that the CO(2) molecule binds to the surface becoming more stable upon physisorption onto the monovacancy site followed by the original C═O bonds weakening upon CO(2) chemisorption onto the vacancy site.

  20. Evaluating Potential for Large Releases from CO2 Storage Reservoirs: Analogs, Scenarios, and Modeling Needs

    International Nuclear Information System (INIS)

    Birkholzer, Jens; Pruess, Karsten; Lewicki, Jennifer; Tsang, Chin-Fu; Karimjee, Anhar

    2005-01-01

    While the purpose of geologic storage of CO 2 in deep saline formations is to trap greenhouse gases underground, the potential exists for CO 2 to escape from the target reservoir, migrate upward along permeable pathways, and discharge at the land surface. Such discharge is not necessarily a serious concern, as CO 2 is a naturally abundant and relatively benign gas in low concentrations. However, there is a potential risk to health, safety and environment (HSE) in the event that large localized fluxes of CO 2 were to occur at the land surface, especially where CO 2 could accumulate. In this paper, we develop possible scenarios for large CO 2 fluxes based on the analysis of natural analogues, where large releases of gas have been observed. We are particularly interested in scenarios which could generate sudden, possibly self-enhancing, or even eruptive release events. The probability for such events may be low, but the circumstances under which they might occur and potential consequences need to be evaluated in order to design appropriate site selection and risk management strategies. Numerical modeling of hypothetical test cases is needed to determine critical conditions for such events, to evaluate whether such conditions may be possible at designated storage sites, and, if applicable, to evaluate the potential HSE impacts of such events and design appropriate mitigation strategies

  1. Discrete Element Modeling of Micro-scratch Tests: Investigation of Mechanisms of CO2 Alteration in Reservoir Rocks

    Science.gov (United States)

    Sun, Zhuang; Espinoza, D. Nicolas; Balhoff, Matthew T.; Dewers, Thomas A.

    2017-12-01

    The injection of CO2 into geological formations leads to geochemical re-equilibrium between the pore fluid and rock minerals. Mineral-brine-CO2 reactions can induce alteration of mechanical properties and affect the structural integrity of the storage formation. The location of alterable mineral phases within the rock skeleton is important to assess the potential effects of mineral dissolution on bulk geomechanical properties. Hence, although often disregarded, the understanding of particle-scale mechanisms responsible for alterations is necessary to predict the extent of geomechanical alteration as a function of dissolved mineral amounts. This study investigates the CO2-related rock chemo-mechanical alteration through numerical modeling and matching of naturally altered rocks probed with micro-scratch tests. We use a model that couples the discrete element method (DEM) and the bonded particle model (BPM) to perform simulations of micro-scratch tests on synthetic rocks that mimic Entrada sandstone. Experimental results serve to calibrate numerical scratch tests with DEM-BPM parameters. Sensitivity analyses indicate that the cement size and bond shear strength are the most sensitive microscopic parameters that govern the CO2-induced alteration in Entrada sandstone. Reductions in cement size lead to decrease in scratch toughness and an increase in ductility in the rock samples. This work demonstrates how small variations of microscopic bond properties in cemented sandstone can lead to significant changes in macroscopic large-strain mechanical properties.

  2. Photocatalytic Reduction of CO2 from Simulated Flue Gas with Colored Anatase

    Directory of Open Access Journals (Sweden)

    Yebin Guan

    2018-02-01

    Full Text Available Photocatalytic reduction with sunlight is an economical and promising advanced approach for reducing the excessive emissions of CO2 from the combustion of fossil fuels. Aimed at practical applications, a type of inexpensive colored anatase material was used to evaluate CO2 photoreduction performance on a platform with a continuous flow of gas mixtures (10 vol % CO2, 90% N2, which resembles realistic flue gas conditions. The results showed an enhanced photocatalytic activity compared with standard P25 and significant improvement over pristine anatase. Based on a series of characterization techniques, we propose that the oxygen vacancies and surface hydroxyl groups on colored anatase can reduce the bandgap and assist the binding of CO2 molecules. Our results showed that photoreduction of CO2 is feasible under practical conditions, and the efficiency could be improved through modification of catalysts.

  3. Modelling the impact of EVs on electricity generation, costs and CO2 emissions

    International Nuclear Information System (INIS)

    Calnan, P.; Deane, J.P.; Ó Gallachóir, B.P.

    2013-01-01

    This paper focuses on the impact of electric vehicles on electricity generation in Ireland in 2025 based on five alternative generation portfolios. The year 2025 was selected for assessment due to the information on the composition of the five generation portfolios from Eirgrid the system operator in Ireland being provided. Detailed market simulations were undertaken on the five possible generation portfolios to assess the impact of the Government targets for electric vehicles on the generation costs, emissions, generation stack and the cost to load of this additional demand. This paper also studied the impact between a standard and least cost electric vehicle loading regime to ascertain the benefits that could be achieved. The results show that gas will be the dominant source of electricity generation to load electric vehicles and that wind as an electricity source will experience a minor reduction in curtailment, with the least cost charging profile showing a more pronounced reduction. The capital benefits of the Standard and Least Cost EV load are found to be negligible. The portfolios studied generated CO 2 emissions per kilometre between 52 and 70 gCO 2 /km. All portfolios with the exception of coal were found to comply with EU regulation 443/2009. - Highlights: • This paper focuses on the impact of electric vehicles on electricity generation in Ireland in 2025. • It uses the PLEXOS software package by Energy Exemplar to model the Irish electricity market. • Government targets for electric vehicle penetration have a limited impact on the power system. • Electric vehicles will meet EU requirements in terms of emissions created per kilometre

  4. Thermodynamic modelling of a recompression CO2 power cycle for low temperature waste heat recovery

    International Nuclear Information System (INIS)

    Banik, Shubham; Ray, Satyaki; De, Sudipta

    2016-01-01

    Highlights: • Thermodynamic model for recompression T-CO 2 is developed. • Energetic and exergetic analysis compared with S-CO 2 and Reg. Brayton cycle. • Maximum efficiency of 13.6% is obtained for T-CO 2 cycle. • Optimum recompression ratio of 0.48 is obtained for minimum irreversibility. • Reg. Brayton has better efficiency, T-CO 2 offers minimum irreversibility. - Abstract: Due to the rising prices of conventional fossil fuels, increasing the overall thermal efficiency of a power plant is essential. One way of doing this is waste heat recovery. This recovery is most difficult for low temperature waste heat, below 240 °C, which also covers majority of the waste heat source. Carbon dioxide, with its low critical temperature and pressure, offers an advantage over ozone-depleting refrigerants used in Organic Rankine Cycles (ORCs) and hence is most suitable for the purpose. This paper introduces parametric optimization of a transcritical carbon dioxide (T-CO 2 ) power cycle which recompresses part of the total mass flow of working fluid before entering the precooler, thereby showing potential for higher cycle efficiency. Thermodynamic model for a recompression T-CO 2 power cycle has been developed with waste heat source of 2000 kW and at a temperature of 200 °C. Results obtained from this model are analysed to estimate effects on energetic and exergetic performances of the power cycle with varying pressure and mass recompression ratio. Higher pressure ratio always improves thermodynamic performance of the cycle – both energetic and exergetic. Higher recompression ratio also increases exergetic efficiency of the cycle. However, it increases energy efficiency, only if precooler inlet temperature remains constant. Maximum thermal efficiency of the T-CO 2 cycle with a recompression ratio of 0.26 has been found to be 13.6%. To minimize total irreversibility of the cycle, an optimum ratio of 0.48 was found to be suitable.

  5. Analysis of CO2 separation and simulation of a partially wetted hollow fiber membrane contactor.

    Science.gov (United States)

    Keshavarz, P; Fathikalajahi, J; Ayatollahi, S

    2008-04-15

    A steady state model was developed for a microporous hollow fiber membrane contactor operated under partially wetted conditions accompanied by chemical reactions, to analyze CO2 absorption into the aqueous solution of diethanolamine (DEA). The proposed diffusion-reaction model contains reversible chemical reactions in the liquid bulk as well as wetted parts of the membrane pores. A numerical scheme was employed to solve the simultaneous nonlinear mathematical expressions, and the results were validated with experimental data in the literature. The gas phase concentration and velocity profile in axial direction inside the shell, liquid concentration profile in axial and radial directions inside the fibers, and also those within the wetted parts of the pores were predicted by using the model. The results of the model and proposed numerical scheme show that membrane wetting, even in very low fractions, can decrease the absorption flux significantly. The wetting fraction of membrane was predicted both with and without consideration of chemical reactions inside the wetted pores. The results indicate that the chemical reactions inside the wetted pores, which have been disregarded in the literature, have considerable effects on the prediction of membrane wetting fraction.

  6. Taxing CO2 and subsidising biomass: Analysed in a macroeconomic and sectoral model

    DEFF Research Database (Denmark)

    Klinge Jacobsen, Henrik

    2000-01-01

    This paper analyses the combination of taxes and subsidies as an instrument to enable a reduction in CO2 emission. The objective of the study is to compare recycling of a CO2 tax revenue as a subsidy for biomass use as opposed to traditional recycling such as reduced income or corporate taxation....... A model of Denmark's energy supply sector is used to analyse the e€ect of a CO2 tax combined with using the tax revenue for biomass subsidies. The energy supply model is linked to a macroeconomic model such that the macroeconomic consequences of tax policies can be analysed along with the consequences...... for speci®c sectors such as agriculture. Electricity and heat are produced at heat and power plants utilising fuels which minimise total fuel cost, while the authorities regulate capacity expansion technologies. The e€ect of fuel taxes and subsidies on fuels is very sensitive to the fuel substitution...

  7. Effect of recent observations on Asian CO2 flux estimates by transport model inversions

    International Nuclear Information System (INIS)

    Maksyutov, Shamil; Patra, Prabir K.; Machida, Toshinobu; Mukai, Hitoshi; Nakazawa, Takakiyo; Inoue, Gen

    2003-01-01

    We use an inverse model to evaluate the effects of the recent CO 2 observations over Asia on estimates of regional CO 2 sources and sinks. Global CO 2 flux distribution is evaluated using several atmospheric transport models, atmospheric CO 2 observations and a 'time-independent' inversion procedure adopted in the basic synthesis inversion by the Transcom-3 inverse model intercomparison project. In our analysis we include airborne and tower observations in Siberia, continuous monitoring and airborne observations over Japan, and airborne monitoring on regular flights on Tokyo-Sydney route. The inclusion of the new data reduces the uncertainty of the estimated regional CO 2 fluxes for Boreal Asia (Siberia), Temperate Asia and South-East Asia. The largest effect is observed for the emission/sink estimate for the Boreal Asia region, where introducing the observations in Siberia reduces the source uncertainty by almost half. It also produces an uncertainty reduction for Boreal North America. Addition of the Siberian airborne observations leads to projecting extra sinks in Boreal Asia of 0.2 Pg C/yr, and a smaller change for Europe. The Tokyo-Sydney observations reduce and constrain the Southeast Asian source

  8. Measurement and modeling of CO2 diffusion coefficient in Saline Aquifer at reservoir conditions

    Science.gov (United States)

    Azin, Reza; Mahmoudy, Mohamad; Raad, Seyed; Osfouri, Shahriar

    2013-12-01

    Storage of CO2 in deep saline aquifers is a promising techniques to mitigate global warming and reduce greenhouse gases (GHG). Correct measurement of diffusivity is essential for predicting rate of transfer and cumulative amount of trapped gas. Little information is available on diffusion of GHG in saline aquifers. In this study, diffusivity of CO2 into a saline aquifer taken from oil field was measured and modeled. Equilibrium concentration of CO2 at gas-liquid interface was determined using Henry's law. Experimental measurements were reported at temperature and pressure ranges of 32-50°C and 5900-6900 kPa, respectively. Results show that diffusivity of CO2 varies between 3.52-5.98×10-9 m2/s for 5900 kPa and 5.33-6.16×10-9 m2/s for 6900 kPa initial pressure. Also, it was found that both pressure and temperature have a positive impact on the measures of diffusion coefficient. Liquid swelling due to gas dissolution and variations in gas compressibility factor as a result of pressure decay was found negligible. Measured diffusivities were used model the physical model and develop concentration profile of dissolved gas in the liquid phase. Results of this study provide unique measures of CO2 diffusion coefficient in saline aquifer at high pressure and temperature conditions, which can be applied in full-field studies of carbon capture and sequestration projects.

  9. Stable isotope reactive transport modeling in water-rock interactions during CO2 injection

    Science.gov (United States)

    Hidalgo, Juan J.; Lagneau, Vincent; Agrinier, Pierre

    2010-05-01

    Stable isotopes can be of great usefulness in the characterization and monitoring of CO2 sequestration sites. Stable isotopes can be used to track the migration of the CO2 plume and identify leakage sources. Moreover, they provide unique information about the chemical reactions that take place on the CO2-water-rock system. However, there is a lack of appropriate tools that help modelers to incorporate stable isotope information into the flow and transport models used in CO2 sequestration problems. In this work, we present a numerical tool for modeling the transport of stable isotopes in groundwater reactive systems. The code is an extension of the groundwater single-phase flow and reactive transport code HYTEC [2]. HYTEC's transport module was modified to include element isotopes as separate species. This way, it is able to track isotope composition of the system by computing the mixing between the background water and the injected solution accounting for the dependency of diffusion on the isotope mass. The chemical module and database have been expanded to included isotopic exchange with minerals and the isotope fractionation associated with chemical reactions and mineral dissolution or precipitation. The performance of the code is illustrated through a series of column synthetic models. The code is also used to model the aqueous phase CO2 injection test carried out at the Lamont-Doherty Earth Observatory site (Palisades, New York, USA) [1]. References [1] N. Assayag, J. Matter, M. Ader, D. Goldberg, and P. Agrinier. Water-rock interactions during a CO2 injection field-test: Implications on host rock dissolution and alteration effects. Chemical Geology, 265(1-2):227-235, July 2009. [2] Jan van der Lee, Laurent De Windt, Vincent Lagneau, and Patrick Goblet. Module-oriented modeling of reactive transport with HYTEC. Computers & Geosciences, 29(3):265-275, April 2003.

  10. Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture

    Directory of Open Access Journals (Sweden)

    Wen Zeng

    2015-03-01

    Full Text Available The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300–2100 K, pressure range of 0.1–1.0 MPa, equivalence ratio range of 0.5–2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2.

  11. CO2 Capture for Cement Technology

    DEFF Research Database (Denmark)

    Pathi, Sharat Kumar

    ppmvin 1960 to 390 ppmv in 2012, probably due to human activity. A lot of research is being carried out forreducing CO2emissions from large stationary sources. Ofwhich, the carbonate looping process is anew process and has the potential to reduce CO2emissions with lower energy penalties. Most of thework...... and the main parameter that controls the performance of the carbonator, a process model integrating the carbonate looping process with the cement pyro-process was simulated. The process simulation results indicate that the CO2 emission was only 0.07 kg/ kg cl, with an energy penalty of 2 MJ/kg CO2 captured......Production of cement is an energy intensive process and is the source of considerable CO2emissions. Itis estimated that the cement industry contributes around 8% of total global CO2emissions. CO2is oneof the major greenhouse gases. In the atmosphere, the CO2concentration has increased from 310...

  12. Modeling light use efficiency in a subtropical mangrove forest equipped with CO2 eddy covariance

    Directory of Open Access Journals (Sweden)

    J. G. Barr

    2013-03-01

    Full Text Available Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI derived from the Moderate Resolution Imaging Spectroradiometer (MODIS that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE, and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and

  13. Modeling light use efficiency in a subtropical mangrove forest equipped with CO2 eddy covariance

    Science.gov (United States)

    Barr, J.G.; Engel, V.; Fuentes, J.D.; Fuller, D.O.; Kwon, H.

    2013-01-01

    Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC) systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE), and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt) increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and information about

  14. Modelling the diurnal and seasonal dynamics of soil CO2 exchange in a semiarid ecosystem with high plant-interspace heterogeneity

    Science.gov (United States)

    Gong, Jinnan; Wang, Ben; Jia, Xin; Feng, Wei; Zha, Tianshan; Kellomäki, Seppo; Peltola, Heli

    2018-01-01

    We used process-based modelling to investigate the roles of carbon-flux (C-flux) components and plant-interspace heterogeneities in regulating soil CO2 exchanges (FS) in a dryland ecosystem with sparse vegetation. To simulate the diurnal and seasonal dynamics of FS, the modelling considered simultaneously the CO2 production, transport and surface exchanges (e.g. biocrust photosynthesis, respiration and photodegradation). The model was parameterized and validated with multivariate data measured during the years 2013-2014 in a semiarid shrubland ecosystem in Yanchi, northwestern China. The model simulation showed that soil rewetting could enhance CO2 dissolution and delay the emission of CO2 produced from rooting zone. In addition, an ineligible fraction of respired CO2 might be removed from soil volumes under respiration chambers by lateral water flows and root uptakes. During rewetting, the lichen-crusted soil could shift temporally from net CO2 source to sink due to the activated photosynthesis of biocrust but the restricted CO2 emissions from subsoil. The presence of plant cover could decrease the root-zone CO2 production and biocrust C sequestration but increase the temperature sensitivities of these fluxes. On the other hand, the sensitivities of root-zone emissions to water content were lower under canopy, which may be due to the advection of water flows from the interspace to canopy. To conclude, the complexity and plant-interspace heterogeneities of soil C processes should be carefully considered to extrapolate findings from chamber to ecosystem scales and to predict the ecosystem responses to climate change and extreme climatic events. Our model can serve as a useful tool to simulate the soil CO2 efflux dynamics in dryland ecosystems.

  15. Modelling the diurnal and seasonal dynamics of soil CO2 exchange in a semiarid ecosystem with high plant–interspace heterogeneity

    Directory of Open Access Journals (Sweden)

    J. Gong

    2018-01-01

    Full Text Available We used process-based modelling to investigate the roles of carbon-flux (C-flux components and plant–interspace heterogeneities in regulating soil CO2 exchanges (FS in a dryland ecosystem with sparse vegetation. To simulate the diurnal and seasonal dynamics of FS, the modelling considered simultaneously the CO2 production, transport and surface exchanges (e.g. biocrust photosynthesis, respiration and photodegradation. The model was parameterized and validated with multivariate data measured during the years 2013–2014 in a semiarid shrubland ecosystem in Yanchi, northwestern China. The model simulation showed that soil rewetting could enhance CO2 dissolution and delay the emission of CO2 produced from rooting zone. In addition, an ineligible fraction of respired CO2 might be removed from soil volumes under respiration chambers by lateral water flows and root uptakes. During rewetting, the lichen-crusted soil could shift temporally from net CO2 source to sink due to the activated photosynthesis of biocrust but the restricted CO2 emissions from subsoil. The presence of plant cover could decrease the root-zone CO2 production and biocrust C sequestration but increase the temperature sensitivities of these fluxes. On the other hand, the sensitivities of root-zone emissions to water content were lower under canopy, which may be due to the advection of water flows from the interspace to canopy. To conclude, the complexity and plant–interspace heterogeneities of soil C processes should be carefully considered to extrapolate findings from chamber to ecosystem scales and to predict the ecosystem responses to climate change and extreme climatic events. Our model can serve as a useful tool to simulate the soil CO2 efflux dynamics in dryland ecosystems.

  16. Measurement and modeling of CO2 mass transfer in brine at reservoir conditions

    Science.gov (United States)

    Shi, Z.; Wen, B.; Hesse, M. A.; Tsotsis, T. T.; Jessen, K.

    2018-03-01

    In this work, we combine measurements and modeling to investigate the application of pressure-decay experiments towards delineation and interpretation of CO2 solubility, uptake and mass transfer in water/brine systems at elevated pressures of relevance to CO2 storage operations in saline aquifers. Accurate measurements and modeling of mass transfer in this context are crucial to an improved understanding of the longer-term fate of CO2 that is injected into the subsurface for storage purposes. Pressure-decay experiments are presented for CO2/water and CO2/brine systems with and without the presence of unconsolidated porous media. We demonstrate, via high-resolution numerical calculations in 2-D, that natural convection will complicate the interpretation of the experimental observations if the particle size is not sufficiently small. In such settings, we demonstrate that simple 1-D interpretations can result in an overestimation of the uptake (diffusivity) by two orders of magnitude. Furthermore, we demonstrate that high-resolution numerical calculations agree well with the experimental observations for settings where natural convection contributes substantially to the overall mass transfer process.

  17. Impact of capillary hysteresis and trapping on vertically integrated models for CO2 storage

    Science.gov (United States)

    Doster, F.; Nordbotten, J. M.; Celia, M. A.

    2013-12-01

    Vertically integrated models are frequently applied to study subsurface flow related to CO2 storage scenarios in saline aquifers. In this paper, we study the impact of capillary-pressure hysteresis and CO2 trapping on the integrated constitutive parameter functions. Our results show that for the initial drainage and a subsequent imbibition, trapping is the dominant contributor to hysteresis in integrated models. We also find that for advective processes like injection and plume migration in a sloped aquifer the correct treatment of the hysteretic nature of the capillary fringe is likely of secondary importance. However, for diffusive/dispersive processes such as a redistribution of the CO2 plume due to buoyancy and capillary forces, the hysteretic nature of the capillary fringe may significantly impact the final distribution of the fluids and the timescale of the redistribution.

  18. Optimized CO2-flue gas separation model for a coal fired power plant

    Energy Technology Data Exchange (ETDEWEB)

    Arachchige, Udara S.P.R. [Telemark University College, Porsgrunn (Norway); Mohsin, Muhammad [Telemark University College, Porsgrunn (Norway); Melaaen, Morten C. [Telemark University College, Porsgrunn (Norway); Tel-Tek, Porsgrunn (Norway)

    2013-07-01

    The detailed description of the CO2 removal process using mono-ethylamine (MEA) as a solvent for coal-fired power plant is present in this paper. The rate based Electrolyte NRTL activity coefficient model was used in the Aspen Plus. The complete removal process with re-circulating solvent back to the absorber was implemented with the sequential modular method in Aspen Plus. The most significant cost related to CO2 capture is the energy requirement for re-generating solvent, i.e. re-boiler duty. Parameters’ effects on re-boiler duty were studied, resulting decreased re-boiler duty with the packing height and absorber packing diameter, absorber pressure, solvent temperature, stripper packing height and diameter. On the other hand, with the flue gas temperature, re-boiler duty is increased. The temperature profiles and CO2 loading profiles were used to check the model behavior.

  19. Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO2 and Co-electrolysis

    DEFF Research Database (Denmark)

    Duhn, Jakob Dragsbæk; Jensen, Anker Degn; Wedel, Stig

    2017-01-01

    to prevent its formation. For prediction of carbon formation, the gas composition in the electrode must be known. In this work, the diffusion of gases in the electrode has been modeled with the dusty gas model in 1 and 2 dimensions, and the effect of tortuosity, porosity, temperature, electrode thickness......Carbon formation may occur during CO2 and CO2/H2O electrolysis using solid oxide electrolyzer cells due to the Boudouard reaction (2CO →  CO2 + C(s)). Formed carbon may disintegrate the cell structure and it is therefore of importance to be able to predict when carbon is formed, and take actions......, pore diameter, current density, pitch and rib width has been investigated. It is shown that diffusion limitations on reactant/product transport may lead to carbon formation. The parameters describing the microstructure and the dimensions of the cathode channels and interconnect ribs are found to have...

  20. Simple model to estimate the contribution of atmospheric CO2 to the Earth's greenhouse effect

    Science.gov (United States)

    Wilson, Derrek J.; Gea-Banacloche, Julio

    2012-04-01

    We show how the CO2 contribution to the Earth's greenhouse effect can be estimated from relatively simple physical considerations and readily available spectroscopic data. In particular, we present a calculation of the "climate sensitivity" (that is, the increase in temperature caused by a doubling of the concentration of CO2) in the absence of feedbacks. Our treatment highlights the important role played by the frequency dependence of the CO2 absorption spectrum. For pedagogical purposes, we provide two simple models to visualize different ways in which the atmosphere might return infrared radiation back to the Earth. The more physically realistic model, based on the Schwarzschild radiative transfer equations, uses as input an approximate form of the atmosphere's temperature profile, and thus includes implicitly the effect of heat transfer mechanisms other than radiation.

  1. Modeling Karst Ecosystem-Atmosphere CO2 Exchange: The Importance of Ventilation for Carbonate Geochemistry

    Science.gov (United States)

    Roland, M.; Serrano-Ortiz, P.; Godderis, Y.; Kowalski, A. S.; Janssens, I.

    2011-12-01

    Global carbonate weathering is considered a small carbon flux when compared with biogenic CO2 fluxes. This is, however, a question of time and space. In karst regions, it has been shown that biogenic fluxes are not always dominant. CO2 exchange patterns have been reported there that cannot be explained by biological processes: disproportionate outgassing during daytime or nighttime CO2 uptake during periods when all vegetation is senescent. These phenomena have previously been attributed to carbonate weathering reactions or biocrust activity, but their associated CO2 exchange rates are considered too small [Serrano-Ortiz et al., 2010]. Here, we report a novel mechanism through which carbonate weathering, exacerbated by subterranean ventilation, dominates the diel pattern of land-atmosphere CO2 exchange in karst areas. Ventilation is an efficient air mass transfer process (including pressure pumping, deep penetration of eddies and thermal expansion of air) that occurs in all porous media, when pores are connected and not blocked by water. Due to its high porosity and the presence of caves, fissures and cracks, karts systems are very prone to ventilation. When soil CO2 concentrations are rapidly brought into disequilibrium by ventilation, CO2 fluxes associated with carbonate weathering can exceed those associated with biological activity. The biology-based standardized partitioning schemes that are used by a large community of scientists, are then no longer applicable and gas exchange measurements fail to reveal any information on the biological activity. By incorporating ventilation processes into the mineral weathering model WITCH [Goddéris et al., 2006], we were able to quantify the contribution of carbonate geochemistry to the synoptic CO2 fluxes on karst ecosystems. [1] Goddéris, Y., L. M. Francois, A. Probst, J. Schott, D. Moncoulon, D. Labat, and D. Viville (2006), Modelling weathering processes at the catchment scale: The WITCH numerical model, Geochim

  2. EuCo2P2 : A model molecular-field helical Heisenberg antiferromagnet

    Science.gov (United States)

    Sangeetha, N. S.; Cuervo-Reyes, Eduardo; Pandey, Abhishek; Johnston, D. C.

    2016-07-01

    The metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below TN=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the a b plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ , high-field magnetization, and magnetic heat capacity of EuCo2P2 single crystals at temperature T ≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ˜T3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and BaCo2P2 , respectively. These values are enhanced by a factor of ˜2.5 above those found from DFT electronic structure calculations for the two compounds. The calculations also find ferromagnetic Eu-Eu exchange interactions within the a b plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χa b(T ≤TN) .

  3. Microbial Priming and Protected Carbon Responses to Elevated CO2 at Local to Global Scales: a New Modeling Approach

    Science.gov (United States)

    Sulman, B. N.; Oishi, C.; Shevliakova, E.; Pacala, S. W.

    2013-12-01

    The soil carbon formulations commonly used in global carbon cycle models and Earth System models (ESMs) are based on first-order decomposition equations, where turnover of carbon is determined only by the size of the carbon pool and empirical functions of responses to temperature and moisture. These models do not include microbial dynamics or protection of carbon in microaggregates and mineral complexes, making them incapable of simulating important soil processes like priming and the influence of soil physical structure on carbon turnover. We present a new soil carbon dynamics model - Carbon, Organisms, Respiration, and Protection in the Soil Environment (CORPSE) - that explicitly represents microbial biomass and protected carbon pools. The model includes multiple types of carbon with different chemically determined turnover rates that interact with a single dynamic microbial biomass pool, allowing the model to simulate priming effects. The model also includes the formation and turnover of protected carbon that is inaccessible to microbial decomposers. The rate of protected carbon formation increases with microbial biomass. CORPSE has been implemented both as a stand-alone model and as a component of the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) ESM. We calibrated the model against measured soil carbon stocks from the Duke FACE experiment. The model successfully simulated the seasonal pattern of heterotrophic CO2 production. We investigated the roles of priming and protection in soil carbon accumulation by running the model using measured inputs of leaf litter, fine roots, and root exudates from the ambient and elevated CO2 plots at the Duke FACE experiment. Measurements from the experiment showed that elevated CO2 caused enhanced root exudation, increasing soil carbon turnover in the rhizosphere due to priming effects. We tested the impact of increased root exudation on soil carbon accumulation by comparing model simulations of carbon accumulation under

  4. Numerical modelling of CO2 migration in saline reservoirs using geoelectric and seismic techniques - first results

    Science.gov (United States)

    Hagrey, S. A. Al; Strahser, M. H. P.; Rabbel, W.

    2009-04-01

    The research project "CO2 MoPa" (modelling and parameterisation of CO2 storage in deep saline formations for dimensions and risk analysis) has been initiated in 2008 by partners from different disciplines (e.g. geology, hydrogeology, geochemistry, geophysics, geomechanics, hydraulic engineering and law). It deals with the parameterisation of virtual subsurface storage sites to characterise rock properties, with high pressure-temperature experiments to determine in situ hydro-petrophysical and mechanical parameters, and with modelling of processes related to CCS in deep saline reservoirs. One objective is the estimation of the sensitivity and the resolution of reflection seismic and geoelectrical time-lapse measurements in order to determine the underground distribution of CO2. Compared with seismic, electric resistivity tomography (ERT) has lower resolution, but its permanent installation and continuous monitoring can make it an economical alternative or complement. Seismic and ERT (in boreholes) applications to quantify changes of intrinsic aquifers properties with time are justified by the velocity and resistivity decrease related to CO2 injection. Our numerical 2D/3D modelling reveals the capability of the techniques to map CO2 plumes and changes as a function of thickness, concentration, receiver/electrode configuration, aspect ratio and modelling and inversion constraint parameters. Depending on these factors, some configurations are favoured due to their better spatial resolution and lower artefacts. Acknowledgements This work has been carried out in the framework of "CO2 MoPa" research project funded by the Federal German Ministry of Education and Research (BMBF) and a consortium of energy companies (E.ON Energy, EnBW AG, RWE Dea AG, Stadtwerke Kiel AG, Vattenfall Europe Technology Research GmbH and Wintershall Holding AG).

  5. Experimental and Numerical Modelling of CO2 Atmospheric Dispersion in Hazardous Gas Emission Sites.

    Science.gov (United States)

    Gasparini, A.; sainz Gracia, A. S.; Grandia, F.; Bruno, J.

    2015-12-01

    Under stable atmospheric conditions and/or in presence of topographic depressions, CO2 concentrations can reach high values resulting in lethal effect to living organisms. The distribution of denser than air gases released from the underground is governed by gravity, turbulence and dispersion. Once emitted, the gas distribution is initially driven by buoyancy and a gas cloud accumulates on the ground (gravitational phase); with time the density gradient becomes less important due to dispersion or mixing and gas distribution is mainly governed by wind and atmospheric turbulence (passive dispersion phase). Natural analogues provide evidences of the impact of CO2 leakage. Dangerous CO2 concentration in atmosphere related to underground emission have been occasionally reported although the conditions favouring the persistence of such a concentration are barely studied.In this work, the dynamics of CO2 in the atmosphere after ground emission is assessed to quantify their potential risk. Two approaches have been followed: (1) direct measurement of air concentration in a natural emission site, where formation of a "CO2 lake" is common and (2) numerical atmospheric modelling. Two sites with different morphology were studied: (a) the Cañada Real site, a flat terrain in the Volcanic Field of Campo de Calatrava (Spain); (b) the Solforata di Pomezia site, a rough terrain in the Alban Hills Volcanic Region (Italy). The comparison between field data and model calculations reveal that numerical dispersion models are capable of predicting the formation of CO2 accumulation over the ground as a consequence of underground gas emission. Therefore, atmospheric modelling could be included as a valuable methodology in the risk assessment of leakage in natural degassing systems and in CCS projects. Conclusions from this work provide clues on whether leakage may be a real risk for humans and under which conditions this risk needs to be included in the risk assessment.

  6. Molecular simulation of preferential adsorption of CO2 over CH4 in Na-montmorillonite clay material

    Science.gov (United States)

    Yang, Nannan; Liu, Shuyan; Yang, Xiaoning

    2015-11-01

    Grand canonical Monte Carlo simulations have been conducted to study the adsorption of carbon dioxide and methane, as well as their binary mixtures on Na-montmorillonite clay material. It was found that the adsorption behavior near the clay structure for the two species is distinctively different. The Na-montmorillonite clay shows obviously high adsorption capacity for CO2, as compared with CH4. The adsorption behavior and mechanism have been characterized by the interlayer interfacial structures and isosteric heats of adsorption. Meanwhile, the mixture adsorption demonstrates that CO2 molecules with enhanced adsorption strength are able to competitively replace CH4 molecules within the clay structure. The high separation selectivity of CO2 over CH4 implies the possibility of separating CO2 from natural gas mixtures using the clay minerals. The interlayer sodium cations and negatively charged clay surface can provide enhanced interaction with CO2 molecules that have high quadrupole moment, which is responsible for the higher adsorption loading of CO2.

  7. Dry (CO2) reforming of methane over Pt catalysts studied by DFT and kinetic modeling

    International Nuclear Information System (INIS)

    Niu, Juntian; Du, Xuesen; Ran, Jingyu; Wang, Ruirui

    2016-01-01

    Graphical abstract: - Highlights: • CH appears to be the most abundant species on Pt(1 1 1) surface in CH 4 dissociation. • CO 2 * + H* → COOH* + * → CO* + OH* is the dominant reaction pathway in CO 2 activation. • Major reaction pathway in CH oxidation: CH* + OH* → CHOH* + * → CHO* + H* → CO* + 2H*. • C* + OH* → COH* + * → CO* + H* is the dominant reaction pathway in C oxidation. - Abstract: Dry reforming of methane (DRM) is a well-studied reaction that is of both scientific and industrial importance. In order to design catalysts that minimize the deactivation and improve the selectivity and activity for a high H 2 /CO yield, it is necessary to understand the elementary reaction steps involved in activation and conversion of CO 2 and CH 4 . In our present work, a microkinetic model based on density functional theory (DFT) calculations is applied to explore the reaction mechanism for methane dry reforming on Pt catalysts. The adsorption energies of the reactants, intermediates and products, and the activation barriers for the elementary reactions involved in the DRM process are calculated over the Pt(1 1 1) surface. In the process of CH 4 direct dissociation, the kinetic results show that CH dissociative adsorption on Pt(1 1 1) surface is the rate-determining step. CH appears to be the most abundant species on the Pt(1 1 1) surface, suggesting that carbon deposition is not easy to form in CH 4 dehydrogenation on Pt(1 1 1) surface. In the process of CO 2 activation, three possible reaction pathways are considered to contribute to the CO 2 decomposition: (I) CO 2 * + * → CO* + O*; (II) CO 2 * + H* → COOH* + * → CO* + OH*; (III) CO 2 * + H* → mono-HCOO* + * → bi-HCOO* + * [CO 2 * + H* → bi-HCOO* + *] → CHO* + O*. Path I requires process to overcome the activation barrier of 1.809 eV and the forward reaction is calculated to be strongly endothermic by 1.430 eV. In addition, the kinetic results also indicate this process is not easy

  8. Computational fluid dynamics (CFD) simulation of CO2 emission from a thermal power plant in an urban environment.

    Science.gov (United States)

    Toja-Silva, Francisco; Chen, Jia; Hachinger, Stephan

    2017-04-01

    Climate change, a societal challenge for the European Union, is affecting all regions in Europe and has a profound impact on society and environment. It is now clear that the present global warming period is due to the strong anthropogenic greenhouse gas (GHG) emission, occurring at an unprecedented rate. Therefore, the identification and control of the greenhouse gas sources has a great relevance. Since the GHG emissions from cities are the largest human contribution to climate change, the present investigation focuses on the urban environment. Bottom-up annual emission inventories are compiled for most countries. However, a rigorous approach requires to perform experimental measurements in order to verify the official estimates. Measurements of column-averaged dry-air mole fractions of GHG (XGHG) can be used for this. To comprehensively detect and quantify GHG emission sources, these punctual column data, however, have to be extended to the surrounding urban map, requiring a deep understanding of the gas transport. The resulting emission estimation will serve several practical purposes, e.g. the verification of official emission rates and the determination of trends in urban emissions. They will enable the administration to make targeted and economically efficient decisions about mitigation options, and help to stop unintentional and furtive releases. With this aim, this investigation presents a completely new approach to the analysis of the carbon dioxide (CO2) emissions from fossil fuel thermal power plants in urban environments by combining differential column measurements with computational fluid dynamics (CFD) simulations in order to deeply understand the experimental conditions. The case study is a natural gas-fueled cogeneration (combined heat and power, CHP) thermal power plant inside the city of Munich (Germany). The software used for the simulations (OpenFOAM) was modified in order to use the most advanced RANS turbulence modeling (i.e. Durbin) and

  9. Microbial stimulation and succession following a test well injection simulating CO2 leakage into a shallow Newark basin aquifer.

    Science.gov (United States)

    O'Mullan, Gregory; Dueker, M Elias; Clauson, Kale; Yang, Qiang; Umemoto, Kelsey; Zakharova, Natalia; Matter, Juerg; Stute, Martin; Takahashi, Taro; Goldberg, David

    2015-01-01

    In addition to efforts aimed at reducing anthropogenic production of greenhouse gases, geological storage of CO2 is being explored as a strategy to reduce atmospheric greenhouse gas emission and mitigate climate change. Previous studies of the deep subsurface in North America have not fully considered the potential negative effects of CO2 leakage into shallow drinking water aquifers, especially from a microbiological perspective. A test well in the Newark Rift Basin was utilized in two field experiments to investigate patterns of microbial succession following injection of CO2-saturated water into an isolated aquifer interval, simulating a CO2 leakage scenario. A decrease in pH following injection of CO2 saturated aquifer water was accompanied by mobilization of trace elements (e.g. Fe and Mn), and increased bacterial cell concentrations in the recovered water. 16S ribosomal RNA gene sequence libraries from samples collected before and after the test well injection were compared to link variability in geochemistry to changes in aquifer microbiology. Significant changes in microbial composition, compared to background conditions, were found following the test well injections, including a decrease in Proteobacteria, and an increased presence of Firmicutes, Verrucomicrobia and microbial taxa often noted to be associated with iron and sulfate reduction. The concurrence of increased microbial cell concentrations and rapid microbial community succession indicate significant changes in aquifer microbial communities immediately following the experimental CO2 leakage event. Samples collected one year post-injection were similar in cell number to the original background condition and community composition, although not identical, began to revert toward the pre-injection condition, indicating microbial resilience following a leakage disturbance. This study provides a first glimpse into the in situ successional response of microbial communities to CO2 leakage after subsurface

  10. Evaluation of Thermodynamic Models for Predicting Phase Equilibria of CO2 + Impurity Binary Mixture

    Science.gov (United States)

    Shin, Byeong Soo; Rho, Won Gu; You, Seong-Sik; Kang, Jeong Won; Lee, Chul Soo

    2018-03-01

    For the design and operation of CO2 capture and storage (CCS) processes, equation of state (EoS) models are used for phase equilibrium calculations. Reliability of an EoS model plays a crucial role, and many variations of EoS models have been reported and continue to be published. The prediction of phase equilibria for CO2 mixtures containing SO2, N2, NO, H2, O2, CH4, H2S, Ar, and H2O is important for CO2 transportation because the captured gas normally contains small amounts of impurities even though it is purified in advance. For the design of pipelines in deep sea or arctic conditions, flow assurance and safety are considered priority issues, and highly reliable calculations are required. In this work, predictive Soave-Redlich-Kwong, cubic plus association, Groupe Européen de Recherches Gazières (GERG-2008), perturbed-chain statistical associating fluid theory, and non-random lattice fluids hydrogen bond EoS models were compared regarding performance in calculating phase equilibria of CO2-impurity binary mixtures and with the collected literature data. No single EoS could cover the entire range of systems considered in this study. Weaknesses and strong points of each EoS model were analyzed, and recommendations are given as guidelines for safe design and operation of CCS processes.

  11. Sensitivity of Holocene atmospheric CO2 and the modern carbon budget to early human land use: analyses with a process-based model

    Directory of Open Access Journals (Sweden)

    F. Joos

    2011-01-01

    Full Text Available A Dynamic Global Vegetation model coupled to a simplified Earth system model is used to simulate the impact of anthropogenic land cover changes (ALCC on Holocene atmospheric CO2 and the contemporary carbon cycle. The model results suggest that early agricultural activities cannot explain the mid to late Holocene CO2 rise of 20 ppm measured on ice cores and that proposed upward revisions of Holocene ALCC imply a smaller contemporary terrestrial carbon sink. A set of illustrative scenarios is applied to test the robustness of these conclusions and to address the large discrepancies between published ALCC reconstructions. Simulated changes in atmospheric CO2 due to ALCC are less than 1 ppm before 1000 AD and 30 ppm at 2004 AD when the HYDE 3.1 ALCC reconstruction is prescribed for the past 12 000 years. Cumulative emissions of 69 GtC at 1850 and 233 GtC at 2004 AD are comparable to earlier estimates. CO2 changes due to ALCC exceed the simulated natural interannual variability only after 1000 AD. To consider evidence that land area used per person was higher before than during early industrialisation, agricultural areas from HYDE 3.1 were increased by a factor of two prior to 1700 AD (scenario H2. For the H2 scenario, the contemporary terrestrial carbon sink required to close the atmospheric CO2 budget is reduced by 0.5 GtC yr−1. Simulated CO2 remains small even in scenarios where average land use per person is increased beyond the range of published estimates. Even extreme assumptions for preindustrial land conversion and high per-capita land use do not result in simulated CO2 emissions that are sufficient to explain the magnitude and the timing of the late Holocene CO2 increase.

  12. Optimized CO2-flue gas separation model for a coal fired power plant

    OpenAIRE

    Udara S. P. R. Arachchige, Muhammad Mohsin, Morten C. Melaaen

    2013-01-01

    The detailed description of the CO2 removal process using mono-ethylamine (MEA) as a solvent for coal-fired power plant is present in this paper. The rate based Electrolyte NRTL activity coefficient model was used in the Aspen Plus. The complete removal process with re-circulating solvent back to the absorber was implemented with the sequential modular method in Aspen Plus. The most significant cost related to CO2 capture is the energy requirement for re-generating solvent, i.e. re-boiler dut...

  13. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  14. Experimental investigation of CO2-brine-rock interactions at simulated in-situ conditions

    Science.gov (United States)

    Słomski, Piotr; Lutyński, Marcin; Mastalerz, Maria; Szczepański, Jacek; Derkowski, Arkadiusz; Topór, Tomasz

    2017-04-01

    Geological sequestration of carbon dioxide (CO2) in deep formations (e.g. saline aquifers, oil and gas reservoirs and coalbeds) is one of the most promising options for reducing concentration of this anthropogenic greenhouse gas in the atmosphere. CO2 injected into the rock formations can be trapped by several mechanisms including structural and stratigraphic trapping, capillary CO2 trapping, dissolution trapping and mineral trapping. During dissolution trapping, CO2 dissolves in the formation brine and sinks in the reservoir as the CO2-enriched brine has an increased density. In comparison, in mineral trapping, CO2 is bound by precipitating new carbonate minerals. The latter two mechanisms depend on the temperature, pressure, and the mineralogy of the reservoir rock and the chemical composition of the brine. This study discusses laboratory scale alterations of Ordovician and Silurian shale rocks from potential CO2 sequestration site B1 in the Baltic Basin. In the reported experiment, rocks submerged in brine in specially constructed reactors were subjected to CO2 pressure of 30-35 MPa for 30-45 days at temperature of 80 oC. Shale samples were analyzed in terms of mineral composition and mesopore surface area and volume, before and after experiments, by means of X-ray diffraction and N2 low-pressure adsorption, respectively, for possible CO2 induced changes. Comparison of mineral composition before and after experiments demonstrated subtle mineral changes. The most conspicuous was a release of Fe in the form of Fe-oxyhydroxides, most probably related to the decomposition of Fe-bearing minerals like pyrite, chlorite and, less frequently, ankerite. With regard to porosity, interestingly, the most significant increase in mesopore surface area and mesopore volume was observed in samples with the largest drop of chlorite amount. The less significant mineral changes were associated with formation of kaolinite related to breakdown of feldspars and dissolution of carbonate

  15. Evaluation of spurious results in the infrared measurement of CO2 isotope ratios due to spectral effects: a computer simulation study

    International Nuclear Information System (INIS)

    Mansfield, C.D.; Rutt, H.N.

    1999-01-01

    The application of infrared spectroscopy to the measurement of carbon isotope ratio breath tests is a promising alternative to conventional techniques, offering relative simplicity and lower costs. However, when designing such an instrument one should be conscious of several spectral effects that may be misinterpreted as changes in the isotope concentration and which therefore lead to spurious results. Through a series of computer simulations which model the behaviour of the CO 2 absorption spectrum, the risk these effects pose to reliable measurement of 13 CO 2 / 12 CO 2 ratios and the measures required to eliminate them are evaluated. The computer model provides a flexible high-resolution spectrum of the four main isotopomer fundamental transitions and fifteen of their most significant hotband transitions. It is demonstrated that the infrared source, infrared windows and breath sample itself all exhibit strong temperature-induced errors but pressure effects do not produce significant errors. We conclude that for reliable measurement of 13 CO 2 / 12 CO 2 ratios using infrared spectroscopy no pressure controls are required, window effects are eliminated using windows wedged at a minimum angle of 0.8-2.2 mrad, depending on the material, and the temperature sensitivity of source and gas cells necessitates stabilization to an accuracy of at least 0.2 K. (author)

  16. Modeling CO2 laser ablation impulse of polymers in vapor and plasma regimes

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.

    2009-01-01

    An improved model for CO 2 laser ablation impulse in polyoxymethylene and similar polymers is presented that describes the transition effects from the onset of vaporization to the plasma regime in a continuous fashion. Several predictions are made for ablation behavior.

  17. Evaluation and selection of sensing materials for carbon dioxide (CO 2) sensor by molecular modeling

    NARCIS (Netherlands)

    Chen, X.P.; Wong, C.K.Y.; Yuan, C.A.; Zhang, G.Q.

    2011-01-01

    We report a molecular modeling study to evaluate and select conducting polymers (CPs) as the sensing materials of carbon dioxide (CO2) sensor. The interaction between polymer and gas and the adsorption of the gas molecules in the polymer matrix are investigated. Polymers considered for this work

  18. Evaluation and selection of sensing materials for carbon dioxide (CO2) sensor by molecular modeling

    NARCIS (Netherlands)

    Chen, X.P.; Wong, C.K.Y.; Yuan, C.A.; Zhang, G.Q.

    2011-01-01

    We report a molecular modeling study to evaluate and select conducting polymers (CPs) as the sensing materials of carbon dioxide (CO2) sensor. The interaction between polymer and gas and the adsorption of the gas molecules in the polymer matrix are investigated. Polymers considered for this work

  19. Inferring CO2 Fluxes from OCO-2 for Assimilation into Land Surface Models to Calculate Net Ecosystem Exchange

    Science.gov (United States)

    Prouty, R.; Radov, A.; Halem, M.; Nearing, G. S.

    2016-12-01

    Investigations of mid to high latitude atmospheric CO2 show a growing seasonal amplitude. Land surface models poorly predict net ecosystem exchange (NEE) and are unable to substantiate these sporadic observations. An investigation of how the biosphere has reacted to changes in atmospheric CO2 is essential to our understanding of potential climate-vegetation feedbacks. A global, seasonal investigation of CO2-flux is then necessary in order to assimilate into land surface models for improving the prediction of annual NEE. The Atmospheric Radiation Measurement program (ARM) of DOE collects CO2-flux measurements (in addition to CO2 concentration and various other meteorological quantities) at several towers located around the globe at half hour temporal frequencies. CO2-fluxes are calculated via the eddy covariance technique, which utilizes CO2-densities and wind velocities to calculate CO2-fluxes. The global coverage of CO2 concentrations as provided by the Orbiting Carbon Observatory (OCO-2) provide satellite-derived CO2 concentrations all over the globe. A framework relating the satellite-inferred CO2 concentrations collocated with the ground-based ARM as well as Ameriflux stations would enable calculations of CO2-fluxes far from the station sites around the entire globe. Regression techniques utilizing deep-learning neural networks may provide such a framework. Additionally, meteorological reanalysis allows for the replacement of the ARM multivariable meteorological variables needed to infer the CO2-fluxes. We present the results of inferring CO2-fluxes from OCO-2 CO2 concentrations for a two year period, Sept. 2014- Sept. 2016 at the ARM station located near Oklahoma City. A feed-forward neural network (FFNN) is used to infer relationships between the following data sets: F([ARM CO2-density], [ARM Meteorological Data]) = [ARM CO2-Flux] F([OCO-2 CO2-density],[ARM Meteorological Data]) = [ARM CO2-Flux] F([ARM CO2-density],[Meteorological Reanalysis]) = [ARM CO2-Flux

  20. Solubility of grape seed oil in supercritical CO2: Experiments and modeling

    International Nuclear Information System (INIS)

    Duba, Kurabachew Simon; Fiori, Luca

    2016-01-01

    Highlights: • Solubility of grape seed oil in SC-CO 2 for P: 20–50 MPa and T: 313–343 K. • Experimental procedure: dynamic method and oil dispersed on the surface of glass beads. • Eight density-based models and a thermodynamic model to fit the experimental data. • All the models predict the solubility of grape seed oil in SC-CO 2 to a reasonable degree. • Models by Chrastil, del Valle and Aguilera, Kumar and Johnston, and the thermodynamic model are preferable. - Abstract: The solubility of grape (Vitis vinifera L.) seed oil in supercritical CO 2 was measured in the temperature range 313–343 K and pressure range 20–50 MPa using the dynamic technique. Several data and global trends were reported. The results show that, at constant temperature, the solubility increases with the increase in pressure, while the effect of the temperature is different for low and high pressure. The experimental data were modeled by eight density-based models and a thermodynamic model based on the Peng-Robinson equation of state. By best fitting procedures, the “free parameters” of the various models were calculated: in general, all the tested models have proved to be able to predict the solubility of grape seed oil in supercritical CO 2 . Differences in model capabilities have been discussed based on the main characteristics of the various models, evidencing their distinct and common features. The predictive capability of the thermodynamic model was comparable to that of the density-based models.

  1. Stable isotope and modelling evidence for CO2 as a driver of glacial–interglacial vegetation shifts in southern Africa

    Directory of Open Access Journals (Sweden)

    F. J. Bragg

    2013-03-01

    Full Text Available Atmospheric CO2 concentration is hypothesized to influence vegetation distribution via tree–grass competition, with higher CO2 concentrations favouring trees. The stable carbon isotope (δ13C signature of vegetation is influenced by the relative importance of C4 plants (including most tropical grasses and C3 plants (including nearly all trees, and the degree of stomatal closure – a response to aridity – in C3 plants. Compound-specific δ13C analyses of leaf-wax biomarkers in sediment cores of an offshore South Atlantic transect are used here as a record of vegetation changes in subequatorial Africa. These data suggest a large increase in C3 relative to C4 plant dominance after the Last Glacial Maximum. Using a process-based biogeography model that explicitly simulates 13C discrimination, it is shown that precipitation and temperature changes cannot explain the observed shift in δ13C values. The physiological effect of increasing CO2 concentration is decisive, altering the C3/C4 balance and bringing the simulated and observed δ13C values into line. It is concluded that CO2 concentration itself was a key agent of vegetation change in tropical southern Africa during the last glacial–interglacial transition. Two additional inferences follow. First, long-term variations in terrestrial δ13Cvalues are not simply a proxy for regional rainfall, as has sometimes been assumed. Although precipitation and temperature changes have had major effects on vegetation in many regions of the world during the period between the Last Glacial Maximum and recent times, CO2 effects must also be taken into account, especially when reconstructing changes in climate between glacial and interglacial states. Second, rising CO2 concentration today is likely to be influencing tree–grass competition in a similar way, and thus contributing to the "woody thickening" observed in savannas worldwide. This second inference points to the importance of experiments to

  2. Improved Characterization and Modeling of Tight Oil Formations for CO2 Enhanced Oil Recovery Potential and Storage Capacity Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, James; Smith, Steven; Kurz, Bethany; Hawthorne, Steven; Jin, Lu; Bosshart, Nicholas; Torres, Jose; Nyberg, Carolyn; Heebink, Loreal; Hurley, John

    2018-03-09

    Tight oil formations such as those in the Bakken petroleum system are known to hold hundreds of billions of barrels of oil in place; however, the primary recovery factor for these plays is typically less than 10%. Tight oil formations, including the Bakken Formation, therefore, may be attractive candidates for enhanced oil recovery (EOR) using CO2. Multiphase fluid behavior and flow in fluid-rich shales can vary substantially depending on the size of pore throats, and properties such as fluid viscosity and density are much different in nanoscale pores than in macroscale pores. Thus it is critical to understand the nature and distribution of nano-, micro-, and macroscale pores and fracture networks. To address these issues, the Energy & Environmental Research Center (EERC) has been conducting a research program entitled “Improved Characterization and Modeling of Tight Oil Formations for CO2 Enhanced Oil Recovery Potential and Storage Capacity Estimation.” The objectives of the project are 1) the use of advanced characterization methods to better understand and quantify the petrophysical and geomechanical factors that control CO2 and oil mobility within tight oil formation samples, 2) the determination of CO2 permeation and oil extraction rates in tight reservoir rocks and organic-rich shales of the Bakken, and 3) the integration of the laboratory-based CO2 permeation and oil extraction data and the characterization data into geologic models and dynamic simulations to develop predictions of CO2 storage resource and EOR in the Bakken tight oil formation. A combination of standard and advanced petrophysical characterization techniques were applied to characterize samples of Bakken Formation tight reservoir rock and shales from multiple wells. Techniques included advanced computer tomography (CT) imaging, scanning electron microscopy (SEM) techniques, whole-core and micro x-ray CT imaging, field emission (FE) SEM, and focused ion beam (FIB) SEM. Selected samples

  3. A workflow for handling heterogeneous 3D models with the TOUGH2 family of codes: Applications to numerical modeling of CO 2 geological storage

    Science.gov (United States)

    Audigane, Pascal; Chiaberge, Christophe; Mathurin, Frédéric; Lions, Julie; Picot-Colbeaux, Géraldine

    2011-04-01

    This paper is addressed to the TOUGH2 user community. It presents a new tool for handling simulations run with the TOUGH2 code with specific application to CO 2 geological storage. This tool is composed of separate FORTRAN subroutines (or modules) that can be run independently, using input and output files in ASCII format for TOUGH2. These modules have been developed specifically for modeling of carbon dioxide geological storage and their use with TOUGH2 and the Equation of State module ECO2N, dedicated to CO 2-water-salt mixture systems, with TOUGHREACT, which is an adaptation of TOUGH2 with ECO2N and geochemical fluid-rock interactions, and with TOUGH2 and the EOS7C module dedicated to CO 2-CH 4 gas mixture is described. The objective is to save time for the pre-processing, execution and visualization of complex geometry for geological system representation. The workflow is rapid and user-friendly and future implementation to other TOUGH2 EOS modules for other contexts (e.g. nuclear waste disposal, geothermal production) is straightforward. Three examples are shown for validation: (i) leakage of CO 2 up through an abandoned well; (ii) 3D reactive transport modeling of CO 2 in a sandy aquifer formation in the Sleipner gas Field, (North Sea, Norway); and (iii) an estimation of enhanced gas recovery technology using CO 2 as the injected and stored gas to produce methane in the K12B Gas Field (North Sea, Denmark).

  4. Phase equilibrium modeling of gas hydrate systems for CO2 capture

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2012-01-01

    Two thermodynamic models capable of describing dissociation pressures of mixed gas clathrate hydrates formed from ternary mixtures of CO2, N2 and liquid water, are presented. Both of the models utilize the Cubic-Plus-Association (CPA) equation of state (EOS) for the thermodynamic description...... literature data for this system, it was not possible to determine unequivocally, which of the two models perform better....

  5. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Boston Univ., MA (United States); Wehr, Richdard [Harvard Univ., Cambridge, MA (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States)

    2016-01-28

    1. Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2). 2. Highlights Accomplishments: • Our isotopic eddy flux record has completed its 5th full year and has been used to independently estimate ecosystem-scale respiration and photosynthesis. • Soil surface chamber isotopic flux measurements were carried out during three growing seasons, in conjunction with a trenching manipulation. Key findings to date (listed by objective): A. Partitioning of Net Ecosystem Exchange: 1. Ecosystem respiration is lower during the day than at night—the first robust evidence of the inhibition of leaf respiration by light (the “Kok effect”) at the ecosystem scale. 2. Because it neglects the Kok effect, the standard NEE partitioning approach overestimates ecosystem photosynthesis (by ~25%) and

  6. Short-term effects of CO2 leakage on the soil bacterial community in a simulated gas leakage scenario

    Directory of Open Access Journals (Sweden)

    Jing Ma

    2017-11-01

    Full Text Available The technology of carbon dioxide (CO2 capture and storage (CCS has provided a new option for mitigating global anthropogenic emissions with unique advantages. However, the potential risk of gas leakage from CO2 sequestration and utilization processes has attracted considerable attention. Moreover, leakage might threaten soil ecosystems and thus cannot be ignored. In this study, a simulation experiment of leakage from CO2 geological storage was designed to investigate the short-term effects of different CO2 leakage concentration (from 400 g m−2 day−1 to 2,000 g m−2 day−1 on soil bacterial communities. A shunt device and adjustable flow meter were used to control the amount of CO2 injected into the soil. Comparisons were made between soil physicochemical properties, soil enzyme activities, and microbial community diversity before and after injecting different CO2 concentrations. Increasing CO2 concentration decreased the soil pH, and the largest variation ranged from 8.15 to 7.29 (p < 0.05. Nitrate nitrogen content varied from 1.01 to 4.03 mg/Kg, while Olsen-phosphorus and total phosphorus demonstrated less regular downtrends. The fluorescein diacetate (FDA hydrolytic enzyme activity was inhibited by the increasing CO2 flux, with the average content varying from 22.69 to 11.25 mg/(Kg h (p < 0.05. However, the increasing activity amplitude of the polyphenol oxidase enzyme approached 230%, while the urease activity presented a similar rising trend. Alpha diversity results showed that the Shannon index decreased from 7.66 ± 0.13 to 5.23 ± 0.35 as the soil CO2 concentration increased. The dominant phylum in the soil samples was Proteobacteria, whose proportion rose rapidly from 28.85% to 67.93%. In addition, the proportion of Acidobacteria decreased from 19.64% to 9.29% (p < 0.01. Moreover, the abundances of genera Methylophilus, Methylobacillus, and Methylovorus increased, while GP4, GP6 and GP7 decreased. Canonical correlation analysis

  7. Enhanced simulations of CH4 and CO2 production in permafrost-affected soils address soil moisture controls on anaerobic decomposition

    Science.gov (United States)

    Graham, D. E.; Zheng, J.; Moon, J. W.; Painter, S. L.; Thornton, P. E.; Gu, B.; Wullschleger, S. D.

    2017-12-01

    Rapid warming of Arctic ecosystems exposes soil organic carbon (SOC) to accelerated microbial decomposition, leading to increased emissions of carbon dioxide (CO2) and methane (CH4) that have a positive feedback on global warming. The magnitude, timing, and form of carbon release will depend not only on changes in temperature, but also on biogeochemical and hydrological properties of soils. In this synthesis study, we assessed the decomposability of thawed organic carbon from active layer soils and permafrost from the Barrow Environmental Observatory across different microtopographic positions under anoxic conditions. The main objectives of this study were to (i) examine environmental conditions and soil properties that control anaerobic carbon decomposition and carbon release (as both CO2 and CH4); (ii) develop a common set of parameters to simulate anaerobic CO2 and CH4 production; and (iii) evaluate uncertainties generated from representations of pH and temperature effects in the current model framework. A newly developed anaerobic carbon decomposition framework simulated incubation experiment results across a range of soil water contents. Anaerobic CO2 and CH4 production have different temperature and pH sensitivities, which are not well represented in current biogeochemical models. Distinct dynamics of CH4 production at -2° C suggest methanogen biomass and growth rate limit activity in these near-frozen soils, compared to warmer temperatures. Anaerobic CO2 production is well constrained by the model using data-informed labile carbon pool and fermentation rate initialization to accurately simulate its temperature sensitivity. On the other hand, CH4 production is controlled by water content, methanogenesis biomass, and the presence of alternative electron acceptors, producing a high temperature sensitivity with large uncertainties for methanogenesis. This set of environmental constraints to methanogenesis is likely to undergo drastic changes due to permafrost

  8. Source strength and dispersion of CO2 releases from high-pressure pipelines: CFD model using real gas equation of state

    International Nuclear Information System (INIS)

    Liu, Xiong; Godbole, Ajit; Lu, Cheng; Michal, Guillaume; Venton, Philip

    2014-01-01

    Highlights: • Validated CFD models for decompression and dispersion of CO 2 releases from pipelines. • Incorporation of real gas EOS into CFD code for source strength estimation. • Demonstration of better performance of SST k–ω turbulence model for jet flow. • Demonstration of better performance of real gas EOS compared to ideal gas EOS. • Demonstration of superiority of CFD models over a commercial risk assessment package. - Abstract: Transportation of CO 2 in high-pressure pipelines forms a crucial link in the ever-increasing application of Carbon Capture and Storage (CCS) technologies. An unplanned release of CO 2 from a pipeline presents a risk to human and animal populations and the environment. Therefore it is very important to develop a deeper understanding of the atmospheric dispersion of CO 2 before the deployment of CO 2 pipelines, to allow the appropriate safety precautions to be taken. This paper presents a two-stage Computational Fluid Dynamics (CFD) study developed (1) to estimate the source strength, and (2) to simulate the subsequent dispersion of CO 2 in the atmosphere, using the source strength estimated in stage (1). The Peng–Robinson (PR) EOS was incorporated into the CFD code. This enabled accurate modelling of the CO 2 jet to achieve more precise source strength estimates. The two-stage simulation approach also resulted in a reduction in the overall computing time. The CFD models were validated against experimental results from the British Petroleum (BP) CO 2 dispersion trials, and also against results produced by the risk management package Phast. Compared with the measurements, the CFD simulation results showed good agreement in both source strength and dispersion profile predictions. Furthermore, the effect of release direction on the dispersion was studied. The presented research provides a viable method for the assessment of risks associated with CCS

  9. Long-term model-based projections of energy use and CO2emissions from the global steel and cement industries

    NARCIS (Netherlands)

    Van Ruijven, Bas J.; Van Vuuren, Detlef P.|info:eu-repo/dai/nl/11522016X; Boskaljon, Willem; Neelis, Maarten L.; Saygin, Deger|info:eu-repo/dai/nl/314118101; Patel, Martin K.

    2016-01-01

    This paper presents a global simulation-model for the steel and cement industries. The model covers the full modelling chain from economic activity, to materials consumption, trade, technology choice, production capacity, energy use and CO2emissions. Without climate policy, the future projections

  10. CO2utilization via a novel anaerobic bioprocess configuration with simulated gas mixture and real stack gas samples.

    Science.gov (United States)

    Daglioglu, S Tugce; Karabey, Burcin; Ozdemir, Guven; Azbar, Nuri

    2017-11-28

    CO 2 , which is considered to be one of the major causes of climate change, has reached to critical levels in the atmosphere due to tremendous consumption of fossil fuels all over the world. In this study, anaerobic bioconversion of CO 2 into bio-methane using a novel bioprocess configuration (HYBRID bioreactor) was studied under mesophilic conditions. Varying ratios of H 2 /CO 2 gas mixture and volumetric feeding rates were investigated and no additional organic matter and trace element were needed throughout the study. The maximum methane production of 19 m 3 CH 4 /m 3 reactor/ d was achieved at a H 2 /CO 2 ratio of 4:1 and feeding rate of 24 m 3 gas/m 3 reactor /d. It was determined that H 2 conversion rate is about 96%. For demonstration purpose, real stack gas sample from a petrochemical industry was also tested under optimized operational conditions. No inhibitory effect from stack gas mixture was observed. This study provided an environmentally friendly and sustainable solution for industries such as petrochemical industry in order to produce extra energy while capturing their waste CO 2 . Thereby, a sustainable and environmentally friendly model solution was presented for industries with high CO 2 emissions. COV: coefficient of variation; Gt: gigatone; IEA: International Energy Agency; IPCC: International Panel on Climate Change; MBBR: moving bed biofilm reactor; MJ: Megajoule; UASB: upflow anaerobic sludge blanket; VFR: volumetric feeding rate.

  11. Analysis of GHG Emission Reduction in South Korea Using a CO2 Transportation Network Optimization Model

    Directory of Open Access Journals (Sweden)

    Suk Ho Jin

    2017-07-01

    Full Text Available Korea’s national carbon capture and storage (CCS master plan aims to commercialize CCS projects by 2030. Furthermore, the Korean government is forced to reduce emissions from various sectors, including industries and power generation, by 219 million tons by 2030. This study analyzes a few scenarios of Korean CCS projects with a CO2 pipeline transportation network optimization model for minimizing the total facility cost and pipeline cost. Our scenarios are based on the “2030 asic roadmap for reducing greenhouse gases” established by the government. The results for each scenario demonstrate that the effective design and implementation of CO2 pipeline network enables the lowering of CO2 units cost. These suggest that CO2 transportation networks, which connect the capture and sequestration parts, will be more important in the future and can be used to substitute and supplement the emission reduction target in case the execution of other reduction options faces uncertainty. Our mathematical model and scenario designs will be helpful for various countries which plan to introduce CCS technology.

  12. Numerical simulations of enhanced gas recovery at the Zalezcze gas field in Poland confirm high CO2 storage capacity and mechanical integrity

    International Nuclear Information System (INIS)

    Klimkowski, Lukasz; Nagy, Stanislaw; Papiernik, Bartosz; Orlic, Bogdan; Kempka, Thomas

    2015-01-01

    Natural gas from the Zalecze gas field located in the Fore-Sudetic Monocline of the Southern Permian Basin has been produced since November 1973, and continuous gas production led to a decrease in the initial reservoir pressure from 151 bar to about 22 bar until 2010. We investigated a prospective enhanced gas recovery operation at the Zalecze gas field by coupled numerical hydro-mechanical simulations to account for the CO 2 storage capacity, trapping efficiency and mechanical integrity of the reservoir, cap-rock and regional faults. Dynamic flow simulations carried out indicate a CO 2 storage capacity of 106.6 Mt with a trapping efficiency of about 43% (45.8 Mt CO 2 ) established after 500 years of simulation. Two independent strategies on the assessment of mechanical integrity were followed by two different modeling groups resulting in the implementation of field- to regional-scale hydro-mechanical simulation models. The simulation results based on application of different constitutive laws for the lithological units show deviations of 31% to 93% for the calculated maximum vertical displacements at the reservoir top. Nevertheless, results of both simulation strategies indicate that fault reactivation generating potential leakage pathways from the reservoir to shallower units is very unlikely due to the low fault slip tendency (close to zero) in the Zechstein cap-rocks. Consequently, our simulation results also emphasise that the supra- and sub-saliferous fault systems at the Zalecze gas field are independent and very likely not hydraulically connected. Based on our simulation results derived from two independent modeling strategies with similar simulation results on fault and cap-rock integrity, we conclude that the investigated enhanced gas recovery scheme is feasible, with a negligibly low risk of relevant fault reactivation or formation fluid leakage through the Zechstein cap-rocks. (authors)

  13. Challenging terrestrial biosphere models with data from the long-term multifactor Prairie Heating and CO2 Enrichment experiment.

    Science.gov (United States)

    De Kauwe, Martin G; Medlyn, Belinda E; Walker, Anthony P; Zaehle, Sönke; Asao, Shinichi; Guenet, Bertrand; Harper, Anna B; Hickler, Thomas; Jain, Atul K; Luo, Yiqi; Lu, Xingjie; Luus, Kristina; Parton, William J; Shu, Shijie; Wang, Ying-Ping; Werner, Christian; Xia, Jianyang; Pendall, Elise; Morgan, Jack A; Ryan, Edmund M; Carrillo, Yolima; Dijkstra, Feike A; Zelikova, Tamara J; Norby, Richard J

    2017-09-01

    Multifactor experiments are often advocated as important for advancing terrestrial biosphere models (TBMs), yet to date, such models have only been tested against single-factor experiments. We applied 10 TBMs to the multifactor Prairie Heating and CO 2 Enrichment (PHACE) experiment in Wyoming, USA. Our goals were to investigate how multifactor experiments can be used to constrain models and to identify a road map for model improvement. We found models performed poorly in ambient conditions; there was a wide spread in simulated above-ground net primary productivity (range: 31-390 g C m -2  yr -1 ). Comparison with data highlighted model failures particularly with respect to carbon allocation, phenology, and the impact of water stress on phenology. Performance against the observations from single-factors treatments was also relatively poor. In addition, similar responses were predicted for different reasons across models: there were large differences among models in sensitivity to water stress and, among the N cycle models, N availability during the experiment. Models were also unable to capture observed treatment effects on phenology: they overestimated the effect of warming on leaf onset and did not allow CO 2 -induced water savings to extend the growing season length. Observed interactive (CO 2  × warming) treatment effects were subtle and contingent on water stress, phenology, and species composition. As the models did not correctly represent these processes under ambient and single-factor conditions, little extra information was gained by comparing model predictions against interactive responses. We outline a series of key areas in which this and future experiments could be used to improve model predictions of grassland responses to global change. © 2017 John Wiley & Sons Ltd.

  14. Response of atmospheric CO2 to changes in land use

    International Nuclear Information System (INIS)

    King, A.W.; Emanuel, W.R.; Post, W.M.

    1991-01-01

    This chapter examines how different histories of CO 2 release from past changes in land use influence the simulation of past and future changes in atmospheric CO 2 . The authors first simulate past change in atmospheric CO 2 using reconstructed histories of land-use CO 2 release from a historical-ecological model of land-use change and CO 2 release. They examine the impact of each history on the coincidence between simulated and observed atmospheric CO 2 . They then compare these CO 2 release histories, and their contribution to coincidence or noncoincidence of simulation and observation, with histories reconstructed by deconvolution of the atmospheric CO 2 record. They conclude by exploring the implications of these deconvolved reconstructions for the simulation of future changes in atmospheric CO 2

  15. Exploratory Research on Simulation of CO2-Brine-Mineral Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhu; Shiao hung Chiang

    2005-11-01

    Application of many carbon sequestration strategies requires knowledge of thermodynamic properties for the extremely complex chemical system of CO{sub 2}-SO{sub 2}-H{sub 2}O-NaCl-CaCl{sub 2}-MgCl{sub 2}. This University Coal Research Phase I program has been successful and highly productive in exploring an approach to develop an equation of state (EOS) to describe thermodynamic properties in the above chemical system. We have compil