WorldWideScience

Sample records for model simulated co2

  1. Simulation of CO2 concentrations at Tsukuba tall tower using WRF-CO2 tracer transport model

    Indian Academy of Sciences (India)

    Srabanti Ballav; Prabir K Patra; Yousuke Sawa; Hidekazu Matsueda; Ahoro Adachi; Shigeru Onogi; Masayuki Takigawa; Utpal K De

    2016-02-01

    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 resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO2 (hereinafter WRF-CO2) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO2 measurements from Tsukuba, Japan (36.05°N, 140.13°E) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO2 concentration variability. The phase of synoptic scale variability in CO2 at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO2 gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor–Yamada–Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO2 over the continental sites.

  2. COUPLING NORSOK CO2 CORROSION PREDICTION MODEL WITH PIPELINES THERMAL/HYDRAULIC MODELS TO SIMULATE CO2 CORROSION ALONG PIPELINES

    Directory of Open Access Journals (Sweden)

    MOKHTAR CHE ISMAIL

    2011-12-01

    Full Text Available Pipelines transporting oil and gas are vulnerable to internal corrosion when water forms a part of the transported fluids. The presence of carbon dioxide (CO2 in the fluid accelerates the corrosion rate due to its reaction with water which results in forming carbonic acid, and hence, water pH is reduced. The corrosion rate prediction is an important task needed to manage and control the corrosion. The prediction can be carried on by selecting one of many empirical and mechanistic models that developed for corrosion rate prediction. One of these models is NORSOK model, an empirical model developed by NORSOK Norwegian standard for CO2 corrosion prediction in straight pipes. In this paper NORSOK model has been coupled to thermal and hydraulic models to predict CO2 corrosion rate along pipelines.

  3. A new simulation model and its application in CO2 short-circuiting transfer welding

    Institute of Scientific and Technical Information of China (English)

    胡连海; 李桓; 李俊岳; 杨立军

    2002-01-01

    A new simulation model of CO2 short-circuiting transfer welding may be employed to develop a new pattern of welding machine and to predict welding process parameters to obtain the optimum welding technology properties. In this paper, a new simulating model is developed according to the AWP (adapting welding physics process) waveform control method. Good agreement is shown between the predicted and experimentally determined results. The model will make an important promotion in the development of CO2 arc welding technique.

  4. 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.

  5. A SIMULATION OF CO2 UPTAKE IN A THREE DIMENSIONAL OCEAN CARBON CYCLE MODEL

    Institute of Scientific and Technical Information of China (English)

    金心; 石广玉

    2001-01-01

    A three-dimensional ocean carbon cycle model which is a general circulation model couple.d with simple biogeochemical processes is used to simulate CO2 uptake by the ocean. The OGCM used is a modified version of the Geophysical Fluid Dynamics Laboratory modular ocean model (MOM2). The ocean chemistry and a simple ocean biota model are included. Principal variables are .total CO2, alkalinity and phosphate. The vertical profile of POC flux observed by sediment traps is adopted, the rain ratio, a ratio of production rate of calcite against that of POC, and the bio-production efficiency should be 0. 06 and 2 per year, separately. The uptake of anthropogenicCO2 by the ocean is studied. Calculated oceanic uptake of anthropogenic CO2 during the 1980s is 2. 05× 10 15g (Pg) per year. The regional distributions of global oceanic CO2 are discussed.

  6. CO2 laser modeling

    Science.gov (United States)

    Johnson, Barry

    1992-01-01

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

  7. 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.

  8. Greenhouse gas simulations with a coupled meteorological and transport model: the predictability of CO2

    Science.gov (United States)

    Polavarapu, Saroja M.; Neish, Michael; Tanguay, Monique; Girard, Claude; de Grandpré, Jean; Semeniuk, Kirill; Gravel, Sylvie; Ren, Shuzhan; Roche, Sébastien; Chan, Douglas; Strong, Kimberly

    2016-09-01

    A new model for greenhouse gas transport has been developed based on Environment and Climate Change Canada's operational weather and environmental prediction models. When provided with realistic posterior fluxes for CO2, the CO2 simulations compare well to NOAA's CarbonTracker fields and to near-surface continuous measurements, columns from the Total Carbon Column Observing Network (TCCON) and NOAA aircraft profiles. This coupled meteorological and tracer transport model is used to study the predictability of CO2. Predictability concerns the quantification of model forecast errors and thus of transport model errors. CO2 predictions are used to compute model-data mismatches when solving flux inversion problems and the quality of such predictions is a major concern. Here, the loss of meteorological predictability due to uncertain meteorological initial conditions is shown to impact CO2 predictability. The predictability of CO2 is shorter than that of the temperature field and increases near the surface and in the lower stratosphere. When broken down into spatial scales, CO2 predictability at the very largest scales is mainly due to surface fluxes but there is also some sensitivity to the land and ocean surface forcing of meteorological fields. The predictability due to the land and ocean surface is most evident in boreal summer when biospheric uptake produces large spatial gradients in the CO2 field. This is a newly identified source of uncertainty in CO2 predictions but it is expected to be much less significant than uncertainties in fluxes. However, it serves as an upper limit for the more important source of transport error and loss of predictability, which is due to uncertain meteorological analyses. By isolating this component of transport error, it is demonstrated that CO2 can only be defined on large spatial scales due to the presence of meteorological uncertainty. Thus, for a given model, there is a spatial scale below which fluxes cannot be inferred simply

  9. New Approaches to Quantifying Transport Model Error in Atmospheric CO2 Simulations

    Science.gov (United States)

    Ott, L.; Pawson, S.; Zhu, Z.; Nielsen, J. E.; Collatz, G. J.; Gregg, W. W.

    2012-01-01

    In recent years, much progress has been made in observing CO2 distributions from space. However, the use of these observations to infer source/sink distributions in inversion studies continues to be complicated by difficulty in quantifying atmospheric transport model errors. We will present results from several different experiments designed to quantify different aspects of transport error using the Goddard Earth Observing System, Version 5 (GEOS-5) Atmospheric General Circulation Model (AGCM). In the first set of experiments, an ensemble of simulations is constructed using perturbations to parameters in the model s moist physics and turbulence parameterizations that control sub-grid scale transport of trace gases. Analysis of the ensemble spread and scales of temporal and spatial variability among the simulations allows insight into how parameterized, small-scale transport processes influence simulated CO2 distributions. In the second set of experiments, atmospheric tracers representing model error are constructed using observation minus analysis statistics from NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA). The goal of these simulations is to understand how errors in large scale dynamics are distributed, and how they propagate in space and time, affecting trace gas distributions. These simulations will also be compared to results from NASA's Carbon Monitoring System Flux Pilot Project that quantified the impact of uncertainty in satellite constrained CO2 flux estimates on atmospheric mixing ratios to assess the major factors governing uncertainty in global and regional trace gas distributions.

  10. 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

  11. 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.

  12. 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 varian

  13. 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

  14. 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.

  15. Process simulation of CO2 capture with aqueous ammonia using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Maribo-Mogensen, Bjørn; van Well, Willy J.M.

    2012-01-01

    The use of aqueous ammonia is a promising option to capture carbon dioxide from power plants thanks to the potential low heat requirement during the carbon dioxide desorption compared to monoethanolamine (MEA) based process. The patented Chilled Ammonia Process developed by Alstom absorbs carbon...... of the process is necessary.In this work, the performance of the carbon dioxide capture process using aqueous ammonia has been analyzed by process simulation. The Extended UNIQUAC thermodynamic model available for the CO2–NH3–H2O system has been implemented in the commercial simulator Aspen Plus®1 by using...... to be in the same range as the values reported recently for advanced amine processes. Assuming that cold cooling water is available, the electricity consumption remains limited. Hence the Chilled Ammonia Process is a promising option for post combustion carbon dioxide capture....

  16. Atmospheric CO2 concentration impacts on maize yield performance under dry conditions: do crop model simulate it right ?

    Science.gov (United States)

    Durand, Jean-Louis; Delusca, Kénel; Boote, Ken; Lizaso, Jon; Manderscheid, Remy; Jochaim Weigel, Hans; Ruane, Alex C.; Rosenzweig, Cynthia; Jones, Jim; Ahuja, Laj; Anapalli, Saseendran; Basso, Bruno; Baron, Christian; Bertuzzi, Patrick; Biernath, Christian; Deryng, Delphine; Ewert, Frank; Gaiser, Thomas; Gayler, Sebastian; Heinlein, Florian; Kersebaum, Kurt Christian; Kim, Soo-Hyung; Müller, Christoph; Nendel, Claas; Olioso, Albert; Priesack, Eckhart; Ramirez-Villegas, Julian; Ripoche, Dominique; Rötter, Reimund; Seidel, Sabine; Srivastava, Amit; Tao, Fulu; Timlin, Dennis; Twine, Tracy; Wang, Enli; Webber, Heidi; Zhao, Shigan

    2017-04-01

    In most regions of the world, maize yields are at risk of be reduced due to rising temperatures and reduced water availability. Rising temperature tends to reduce the length of the growth cycle and the amount of intercepted solar energy. Water deficits reduce the leaf area expansion, photosynthesis and sometimes, with an even more pronounced impact, severely reduce the efficiency of kernel set. In maize, the major consequence of atmospheric CO2 concentration ([CO2]) is the stomatal closure-induced reduction of leaf transpiration rate, which tends to mitigate those negative impacts. Indeed FACE studies report significant positive responses to CO2 of maize yields (and other C4 crops) under dry conditions only. Given the projections by climatologists (typically doubling of [CO2] by the end of this century) projected impacts must take that climate variable into account. However, several studies show a large incertitude in estimating the impact of increasing [CO2] on maize remains using the main crop models. The aim of this work was to compare the simulations of different models using input data from a FACE experiment conducted in Braunschweig during 2 years under limiting and non-limiting water conditions. Twenty modelling groups using different maize models were given the same instructions and input data. Following calibration of cultivar parameters under non-limiting water conditions and under ambient [CO2] treatments of both years, simulations were undertaken for the other treatments: High [ CO2 ] (550 ppm) 2007 and 2008 in both irrigation regimes, and DRY AMBIENT 2007 and 2008. Only under severe water deficits did models simulate an increase in yield for CO2 enrichment, which was associated with higher harvest index and, for those models which simulated it, higher grain number. However, the CO2 enhancement under water deficit simulated by the 20 models was 20 % at most and 10 % on average only, i.e. twice less than observed in that experiment. As in the experiment

  17. CO2 capture in amine solutions: modelling and simulations with non-empirical methods

    Science.gov (United States)

    Andreoni, Wanda; Pietrucci, Fabio

    2016-12-01

    Absorption in aqueous amine solutions is the most advanced technology for the capture of CO2, although suffering from drawbacks that do not allow exploitation on large scale. The search for optimum solvents has been pursued with empirical methods and has also motivated a number of computational approaches over the last decade. However, a deeper level of understanding of the relevant chemical reactions in solution is required so as to contribute to this effort. We present here a brief critical overview of the most recent applications of computer simulations using ab initio methods. Comparison of their outcome shows a strong dependence on the structural models employed to represent the molecular systems in solution and on the strategy used to simulate the reactions. In particular, the results of very recent ab initio molecular dynamics augmented with metadynamics are summarized, showing the crucial role of water, which has been so far strongly underestimated both in the calculations and in the interpretation of experimental data. Indications are given for advances in computational approaches that are necessary if meant to contribute to the rational design of new solvents.

  18. CO2 capture in amine solutions: modelling and simulations with non-empirical methods.

    Science.gov (United States)

    Andreoni, Wanda; Pietrucci, Fabio

    2016-12-21

    Absorption in aqueous amine solutions is the most advanced technology for the capture of CO2, although suffering from drawbacks that do not allow exploitation on large scale. The search for optimum solvents has been pursued with empirical methods and has also motivated a number of computational approaches over the last decade. However, a deeper level of understanding of the relevant chemical reactions in solution is required so as to contribute to this effort. We present here a brief critical overview of the most recent applications of computer simulations using ab initio methods. Comparison of their outcome shows a strong dependence on the structural models employed to represent the molecular systems in solution and on the strategy used to simulate the reactions. In particular, the results of very recent ab initio molecular dynamics augmented with metadynamics are summarized, showing the crucial role of water, which has been so far strongly underestimated both in the calculations and in the interpretation of experimental data. Indications are given for advances in computational approaches that are necessary if meant to contribute to the rational design of new solvents.

  19. Net ecosystem CO2 exchange and evapotranspiration of a sphagnum mire: field measurements and model simulations

    Science.gov (United States)

    Olchev, Alexander; Volkova, Elena; Karataeva, Tatiana; Zatsarinnaya, Dina; Novenko, Elena

    2014-05-01

    The spatial and temporal variability of net ecosystem exchange of CO2 (NEE) and evapotranspiration (ET) of a karst-hole sphagnum peat mire situated at the boundary between broad-leaved and forest-steppe zones in the central part of European Russia (54.06N, 37.59E, 260 m a.s.l.) was described using results of field measurements and simulations with Mixfor-3D model. The area of the mire is about 1.2 ha and it is surrounded by a broadleaved forest stand. It is a typical peat mire according to water and mineral supply as well as to vegetation composition. The vegetation of the peripheral parts of the mire is typical eutrophic whereas the vegetation in its central part is represented by meso-oligothrophic plant communities. To describe the spatial variability of NEE and ET within the mire a portable measuring system consisting of a transparent ventilated chamber combined with an infrared CO2 and H2O analyzer LI-840A (Li-Cor, USA) was used. The measurements were provided along a transect from the southern peripheral part of the mire to its center under sunny clear-sky weather conditions in the period from May to September of 2012 and from May 2013 to October 2013. The chamber method was used for measurements of NEE and ET fluxes because of small size of the mire, a very uniform surrounding forest stand and the mosaic mire vegetation. All these factors promote very heterogeneous exchange conditions within the mire and make it difficult to apply, for example, an eddy covariance method that is widely used for flux measurements in the field. The results of the field measurements showed a significant spatial and temporal variability of NEE and ET that was mainly influenced by incoming solar radiation, air temperature and ground water level. During the entire growing season the central part of the mire was a sink of CO2 for the atmosphere (up to 6.8±4.2 µmol m-2 s-1 in June) whereas its peripheral part, due to strong shading by the surrounding forest, was mainly a source of

  20. A model intercomparison of the tropical precipitation response to a CO2 doubling in aquaplanet simulations

    Science.gov (United States)

    Seo, Jeongbin; Kang, Sarah M.; Merlis, Timothy M.

    2017-01-01

    In the present-day climate, the mean Intertropical Convergence Zone (ITCZ) is north of the equator. We investigate changes in the ITCZ latitude under global warming, using multiple atmospheric models coupled to an aquaplanet slab ocean. The reference climate, with a warmer north from prescribed ocean heating, is perturbed by doubling CO2. Most models exhibit a northward ITCZ shift, but the shift cannot be accounted for by the response of energy flux equator where the atmospheric energy transport (FA) vanishes. The energetics of the simulated circulation shifts are subtle: changes in the efficiency with which the Hadley circulation transports energy, the total gross moist stability (Δm), dominate over mass flux changes in determining δFA. Even when δFA ≈ 0, the ITCZ can shift significantly due to changes in Δm, which have often been neglected previously. The dependence of ITCZ responses on δΔm calls for improved understanding of the physics determining the tropical Δm.

  1. 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 te

  2. An empirical model simulating long-term diurnal CO2 flux for diverse vegetation types

    Directory of Open Access Journals (Sweden)

    A. D. Richardson

    2008-10-01

    Full Text Available We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE. The model is based on the use of a nonrectangular hyperbola for photosynthetic response of canopy and was constructed by using a dataset obtained from the AmeriFlux network and containing continuous eddy covariance CO2 flux from 26 ecosystems over seven biomes. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters with air temperature, vapor pressure deficit, and precipitation. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration had biome-specific responses to environmental variables. The estimated physiological parameters had reasonable magnitudes and seasonal variation and gave reasonable timing of the beginning and end of the growing season over various biomes, but they were less satisfactory for disturbed grassland and savanna than for forests. Comparison with observational data revealed that the diurnal cycle of NEE was generally well predicted all year round by the model. The model gave satisfactory results even for tundra, which had very small amplitudes of NEE variability. These results suggest that this model with biome-specific parameters will be applicable to numerous terrestrial biomes, particularly forest ones.

  3. Structure of the transport uncertainty in mesoscale inversions of CO2 sources and sinks using ensemble model simulations

    Directory of Open Access Journals (Sweden)

    J. Noilhan

    2008-12-01

    Full Text Available We study the characteristics of a statistical ensemble of mesoscale simulations in order to estimate the model error in the simulation of CO2 concentrations. The ensemble consists of ten members and the reference simulation using the operationnal short range forecast PEARP, perturbed by Singular Vector (SV technic. We then used this ensemble of simulations as the initial and boundary conditions for the meso scale model simulations, here the atmospheric transport model Méso-NH, transporting CO2 fluxes from the ISBA-A-gs land surface model. The final ensemble represents the model dependence to the boundary conditions, conserving the physical properties of the dynamical schemes. First, the variance of our ensemble is estimated over the domain, with associated spatial and temporal correlations. Second, we extract the signal from noisy horizontal correlations, due to the limited size ensemble, using diffusion equation modelling. Finally, we compute the diagonal and non-diagonal terms of the observation error covariance matrix and introduced it into our CO2 flux matrix inversion over 18 days of the 2005 intensive campaign CERES over the South West of France. On the horizontal plane, variance of the ensemble follows the discontinuities of the mesoscale structures during the day, but remain locally driven during the night. On the vertical, surface layer variance shows large correlations with the upper levels in the boundary layer (>0.6, down to 0.4 with the low free troposphere. Large temporal correlations were found during the afternoon (>0.5 for several hours, reduced during the night. Diffusion equation model extracted relevant error covariance signals on the horizontal space, and shows reduced correlations over mountain area and during the night over the continent. The posterior error reduction on the inverted CO2 fluxes accounting for the model error correlations illustrates finally the predominance of the temporal over the spatial correlations

  4. Structure of the transport uncertainty in mesoscale inversions of CO2 sources and sinks using ensemble model simulations

    Directory of Open Access Journals (Sweden)

    J. Noilhan

    2009-06-01

    Full Text Available We study the characteristics of a statistical ensemble of mesoscale simulations in order to estimate the model error in the simulation of CO2 concentrations. The ensemble consists of ten members and the reference simulation using the operationnal short range forecast PEARP, perturbed using the Singular Vector technique. We then used this ensemble of simulations as the initial and boundary conditions for the meso scale model (Méso-NH simulations, which uses CO2 fluxes from the ISBA-A-gs land surface model. The final ensemble represents the model dependence to the boundary conditions, conserving the physical properties of the dynamical schemes, but excluding the intrinsic error of the model. First, the variance of our ensemble is estimated over the domain, with associated spatial and temporal correlations. Second, we extract the signal from noisy horizontal correlations, due to the limited size ensemble, using diffusion equation modelling. The computational cost of such ensemble limits the number of members (simulations especially when running online the carbon flux and the atmospheric models. In the theory, 50 to 100 members would be required to explore the overall sensitivity of the ensemble. The present diffusion model allows us to extract a significant part of the noisy error, and makes this study feasable with a limited number of simulations. Finally, we compute the diagonal and non-diagonal terms of the observation error covariance matrix and introduced it into our CO2 flux matrix inversion for 18 days of the 2005 intensive campaign CERES over the South West of France. Variances are based on model-data mismatch to ensure we treat model bias as well as ensemble dispersion, whereas spatial and temporal covariances are estimated with our method. The horizontal structure of the ensemble variance manifests the discontinuities of the mesoscale structures during the day, but remains locally driven during the night. On the vertical, surface layer

  5. 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.

  6. Molecular simulation studies of CO2 adsorption by carbon model compounds for carbon capture and sequestration applications.

    Science.gov (United States)

    Liu, Yangyang; Wilcox, Jennifer

    2013-01-02

    Effects of oxygen-containing surface functionalities on the adsorption of mixtures including CO(2)/CH(4), CO(2)/N(2), and CO(2)/H(2)O have been investigated in the current work. Together with Bader charge analysis, electronic structure calculations have provided the initial framework comprising both the geometry and corresponding charge information required to carry out statistical-based molecular simulations. The adsorption isotherms and selectivity of CO(2) from CO(2)/N(2), CO(2)/CH(4), and CO(2)/H(2)O gas mixtures were determined by grand canonical Monte Carlo simulations at temperature/pressure conditions relevant to carbon capture and sequestration applications. The interactions between the surfaces with induced polarity and nonpolar/polar molecules have been investigated. It has been observed that, due to the induced polarity of the surface functionalization, the selectivity of CO(2) over CH(4) increases from approximately 2 to higher than 5, and the selectivity of CO(2) over N(2) increases from approximately 5 to 20, especially in the low-pressure regime. However, water vapor will always preferentially adsorb over CO(2) in carbon-based systems containing oxygen functionalized surfaces at conditions relevant to carbon capture application. Molecular simulation results indicate that the surface chemistry in micropores is tunable thereby influencing the selectivity for enhanced uptake of CO(2).

  7. An empirical model simulating diurnal and seasonal CO2 flux for diverse vegetation types and climate conditions

    Directory of Open Access Journals (Sweden)

    A. D. Richardson

    2009-04-01

    Full Text Available We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE in various biomes. The model is based on the use of a simple saturated function for photosynthetic response of the canopy, and was constructed using the AmeriFlux network dataset that contains continuous eddy covariance CO2 flux data obtained at 24 ecosystems sites from seven biomes. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration have biome-specific responses to environmental variables. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters based on air temperature, vapor pressure deficit, and annual precipitation. The model was validated using measurements of NEE derived from 10 AmeriFlux and four AsiaFlux ecosystem sites. The predicted NEE had reasonable magnitude and seasonal variation and gave adequate timing for the beginning and end of the growing season; the model explained 83–95% and 76–89% of the observed diurnal variations in NEE for the AmeriFlux and AsiaFlux ecosystem sites used for validation, respectively. The model however worked less satisfactorily in two deciduous broadleaf forests, a grassland, a savanna, and a tundra ecosystem sites where leaf area index changed rapidly. These results suggest that including additional plant physiological parameters may improve the model simulation performance in various areas of biomes.

  8. 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.

  9. Responses to atmospheric CO2 concentrations 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

    2017-01-30

    Elevated atmospheric CO2 concentrations ([CO2 ]) cause direct changes in crop physiological processes (e.g. photosynthesis and stomatal conductance). To represent these CO2 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 CO2 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 [CO2 ] (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 [CO2 ] 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 CO2 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 CO2 responses within models should be prioritized.

  10. Simulation of H2O-vapor and Brine-CO2 in porous media with a Lattice Boltzmann Model.

    Science.gov (United States)

    Schaap, M. G.

    2014-12-01

    This DOE-BES funded study is a collaboration between Oregon State University (led by Dr. Dorthe Wildenschild) and the University of Arizona to investigate pore-scale aspects of capillary trapping to enhance the efficiency of geological CO2 sequestration. For the purposes of this project it is important to correctly simulate the physical conditions under which super-critical CO2 will be present after injection into the host rock. This means that the LB model should be able to handle the pressures, densities, temperatures in deep geological media. A logical way of dealing with is is to combine a single-component LB model with and Equation of State (EOS) that describes the physical interrelations among pressure, temperature and density. Previously, we showed that the Peng-Robinson (PR) EOS provides an excellent fit to super-critical conditions for the pure CO2 system. However, it is necessary to consider multi-component systems as the super-critical CO2 will be present with brines of varying salinity. A natural extension to the work under is to also treat the brine with an EOS. The brine will of be in a sub-critical state and it is therefore important to find an EOS that can faithfully match the physical conditions of brine between temperatures of 300 and 400K and pressures between 7 and 30 MPa. This study will present a number of EOS alternatives that attempt to correctly capture the density of the liquid branch of the water system for relevant temperatures and pressures. We will also propose modifications that allow us to deal with different brine concentrations and compare LB modeled interfacial tension and viscosity with published data. As a secondary objective we investigate whether it is possible to match water-vapor systems under ambient surface conditions relevant for vadose zone transport. Support: DOE DE-FG02-11ER16278

  11. Assessment of North America photosynthetic uptake of CO2 through simulations of COS in a Lagrangian particle dispersion model framework

    Science.gov (United States)

    Chen, H.; Montzka, S. A.; Andrews, A. E.; Sweeney, C.; Jacobson, A. R.; Petron, G.; Trudeau, M.; Miller, B. R.; Karion, A.; Martin, J.; Gerbig, C.; Campbell, J.; Abu-Naser, M.; Berry, J. A.; Baker, I. T.; Nehrkorn, T.; Eluszkiewicz, J.; Tans, P. P.

    2012-12-01

    Improving our understanding of terrestrial gross carbon fluxes, i.e. gross primary production (GPP) and respiration, plays a key role in evaluating feedbacks and thereby improving our ability to predict future climate. Since GPP can only be directly measured on very small scales, estimates of GPP at regional to global scales are derived only from biospheric model simulations. Recent studies suggest that carbonyl sulfide be a useful tracer to provide constraints on GPP, based on the fact that both COS and CO2 are simultaneously taken up by plants. Here we present an assessment of GPP estimates for North America from the Simple Biosphere (SiB) model, the Carnegie-Ames-Stanford Approach (CASA) model, and the MPI-BGC model through atmospheric transport simulations of COS in a Lagrangian particle dispersion model (LPDM) framework. We evaluate the impacts of boundary condition and soil uptake on the GPP estimates we derive. This study uses measurements of COS and CO2 from the NOAA/ESRL tall tower and aircraft air sampling networks, and LPDM simulations backward in time are used to quantify the contribution from different sources to observed mole fractions. A measurement over the continent contains information about terrestrial fluxes provided the upwind, or background concentration is known. Hence, the background state is an important part of the observed signal to be simulated. Empirical boundary curtains are built based on observations at the NOAA/ESRL marine boundary layer stations and from aircraft vertical profiles. These curtains are utilized as the lateral boundary conditions for COS and CO2 for the North American model domain. To assess the uncertainty of the background values for observations, we compare calculated background values based on the empirical curtains and two different models that identify where on the curtain the air entered the model domain: WRF-STILT and HYSPLIT-NAM12. Furthermore, the non-GPP related COS fluxes due to anthropogenic emissions and

  12. Sensitivity of simulated CO2 concentration to regridding of global fossil fuel CO2 emissions

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2014-06-01

    Full Text Available Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Finite grid resolution can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. We test these mismatches by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are: (1 a commonly-used method that allocates emissions to gridcells with no attempt to ensure dynamical consistency with atmospheric transport; (2 an improved method that reallocates emissions to gridcells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from −30.3 Tg C gridcell−1 yr−1 (−3.39 kg C m−2 yr−1 to +30.0 Tg C gridcell−1 yr−1 (+2.6 kg C m−2 yr−1 along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding −32 ppm. The differences implied by not accounting for this dynamical consistency problem are largest at monitoring sites proximal to large coastal urban areas and point sources. These results suggest that studies comparing simulated to observed atmospheric CO2 concentration, such as atmospheric CO2 inversions, must take measures to correct for this potential

  13. 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.

  14. Climate warming due to increasing atmospheric CO2 - Simulations with a multilayer coupled atmosphere-ocean seasonal energy balance model

    Science.gov (United States)

    Li, Peng; Chou, Ming-Dah; Arking, Albert

    1987-01-01

    The transient response of the climate to increasing CO2 is studied using a modified version of the multilayer energy balance model of Peng et al. (1982). The main characteristics of the model are described. Latitudinal and seasonal distributions of planetary albedo, latitude-time distributions of zonal mean temperatures, and latitudinal distributions of evaporation, water vapor transport, and snow cover generated from the model and derived from actual observations are analyzed and compared. It is observed that in response to an atmospheric doubling of CO2, the model reaches within 1/e of the equilibrium response of global mean surface temperature in 9-35 years for the probable range of vertical heat diffusivity in the ocean. For CO2 increases projected by the National Research Council (1983), the model's transient response in annually and globally averaged surface temperatures is 60-75 percent of the corresponding equilibrium response, and the disequilibrium increases with increasing heat diffusivity of the ocean.

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

    Directory of Open Access Journals (Sweden)

    M. Madić

    2013-09-01

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

  16. O2/CO2气氛下单相介质换热器的仿真模型研究%Research on simulation model of single-phase heat exchanger under O2/CO2 atmosphere

    Institute of Scientific and Technical Information of China (English)

    高建强; 侯致福; 尹相雷; 刘宪岭

    2011-01-01

    基于O2/CO2燃烧方式的烟气成分和换热特点,建立了O2/CO2气氛下单相介质换热器的动态数学模型,并开发了通用化的仿真算法模块.以某300 MW富氧煤粉燃烧锅炉概念设计中的过热系统为研究对象,进行了减温水、入口烟温扰动下的仿真试验,结果表明O2/CO2=30/70气氛下过热系统的动态特性与空气气氛的变化趋势一致,但汽温的变化过渡时间缩短,对各扰动的响应更加敏感,可为O2/CO2气氛下过热器的控制系统设计和机组运行提供参考.%Based on the gas composition and the heat transfer characteristics of O2/CO2 combustion technique, this paper established a dynamic mathematical model and developed an engineering modularized simulation model for single-phase heat exchanger under O2/CO2 atmosphere. The simulation tests for the overheat system of a conceptual design of 300 MW oxygen-rich pulverized coal burning boiler were made under the disturbance of spray water and entrance smoke temperature. Simulation results show that the changing trends of overheat system under O2/CO2 = 30/70 and air atmosphere are similar but the transition time of export steam temperature variation is cutting short and the response to each disturbance is more sensitive, which can provide reference for the control system design and units operation under O2/ CO2 atmosphere.

  17. Improving ecophysiological simulation models to predict the impact of elevated atmospheric CO2 concentration on crop productivity

    NARCIS (Netherlands)

    Yin, X.

    2013-01-01

    Background - 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 resear

  18. 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.

  19. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Directory of Open Access Journals (Sweden)

    L. Ammoura

    2012-10-01

    Full Text Available Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI and urban-rural contrasts. Boundary layer heights (BLH at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical

  20. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2012-10-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is challenging, but essential in order to utilize CO2 measurements in an atmospheric inverse framework to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration, during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town-Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 between the surface and the atmosphere. Statistical scores show a good representation of the Urban Heat Island (UHI) and urban-rural contrasts. Boundary layer heights (BLH) at urban, sub-urban and rural sites are well captured, especially the onset time of the BLH increase and its growth rate in the morning, that are essential for tall tower CO2 observatories. Only nocturnal BLH at sub-urban sites are slightly underestimated a few nights, with a bias less than 50 m. At Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the Atmospheric Boundary Layer (ABL) growth reaches the measurement height. The timing of the CO2 cycle is well captured by the model, with only small biases on CO2 concentrations, mainly linked to the misrepresentation of anthropogenic emissions, as the Eiffel site is at the heart of trafic emission sources. At sub-urban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a very strong spatio-temporal variability. The CO2 cycle at these sites is generally well reproduced by the model, even if some biases on the nocturnal maxima appear in the Paris plume parly due to small errors on the vertical transport, or in

  1. Status of CO2 storage in deep saline aquifers with emphasis on modeling approaches and practical simulations

    Science.gov (United States)

    Celia, M. A.; Bachu, S.; Nordbotten, J. M.; Bandilla, K. W.

    2015-09-01

    Carbon capture and storage (CCS) is the only viable technology to mitigate carbon emissions while allowing continued large-scale use of fossil fuels. The storage part of CCS involves injection of carbon dioxide, captured from large stationary sources, into deep geological formations. Deep saline aquifers have the largest identified storage potential, with estimated storage capacity sufficient to store emissions from large stationary sources for at least a century. This makes CCS a potentially important bridging technology in the transition to carbon-free energy sources. Injection of CO2 into deep saline aquifers leads to a multicomponent, multiphase flow system, in which geomechanics, geochemistry, and nonisothermal effects may be important. While the general system can be highly complex and involve many coupled, nonlinear partial differential equations, the underlying physics can sometimes lead to important simplifications. For example, the large density difference between injected CO2 and brine may lead to relatively fast buoyant segregation, making an assumption of vertical equilibrium reasonable. Such simplifying assumptions lead to a range of simplified governing equations whose solutions have provided significant practical insights into system behavior, including improved estimates of storage capacity, easy-to-compute estimates of CO2 spatial migration and pressure response, and quantitative estimates of leakage risk. When these modeling studies are coupled with observations from well-characterized injection operations, understanding of the overall system behavior is enhanced significantly. This improved understanding shows that, while economic and policy challenges remain, CO2 storage in deep saline aquifers appears to be a viable technology and can contribute substantially to climate change solutions.

  2. 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 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.

  3. 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

  4. CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project

    Science.gov (United States)

    Lac, C.; Donnelly, R. P.; Masson, V.; Pal, S.; Riette, S.; Donier, S.; Queguiner, S.; Tanguy, G.; Ammoura, L.; Xueref-Remy, I.

    2013-05-01

    Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is a challenging and interesting task needed to be performed in order to utilise CO2 measurements in an atmospheric inverse framework and to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 modelling between the surface and the atmosphere. Statistical scores show a good representation of the urban heat island (UHI) with stronger urban-rural contrasts on temperature at night than during the day by up to 7 °C. Boundary layer heights (BLH) have been evaluated on urban, suburban and rural sites during the campaign, and also on a suburban site over 1 yr. The diurnal cycles of the BLH are well captured, especially the onset time of the BLH increase and its growth rate in the morning, which are essential for tall tower CO2 observatories. The main discrepancy is a small negative bias over urban and suburban sites during nighttime (respectively 45 m and 5 m), leading to a few overestimations of nocturnal CO2 mixing ratios at suburban sites and a bias of +5 ppm. The diurnal CO2 cycle is generally well captured for all the sites. At the Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the atmospheric boundary layer (ABL) growth reaches the measurement height. At suburban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a strong spatio-temporal variability. A sensitivity test without

  5. Evaluation of Equations of State and Mixing Models for Simulating the Brine-CO2 System with a Lattice Boltzmann Model Under Reservoir Conditions

    Science.gov (United States)

    Schaap, M. G.

    2013-12-01

    This DOE-funded study is a collaboration between Oregon State University (led by Dr. Dorthe Wildenschild) and the University of Arizona to investigate pore-scale aspects of capillary trapping to enhance the efficiency of geological CO2 sequestration in deep saline aquifers where super-critical conditions prevail. Compared to most current reservoir-scale studies, our research takes several steps back in scale to observe and model trapping at the pore-scale using a combination of computed micro-tomography imaging (performed by OSU) and multi-phase/multi-component lattice Boltzmann (LB) simulations (carried out by UA). The main objective is to quantify how pore-scale mechanisms translate into continuum scale properties that can subsequently support improved modelling of sequestration at large spatio-temporal scales. For the purposes of this project it is important to correctly simulate the physical conditions under which super-critical CO2 will be present after injection into the host rock. In practice this means that the LB model should be able to handle the pressures (P), densities (ρ), temperatures (T) that prevail in deep geological media. A logical way of dealing with is is to combine a single-component LB model with and Equation of State (EOS) that describes the physical interrelations among P, ρ and T (Yuan and Scheafer, 2006). Previously, we showed that the Peng-Robinson (PR) EOS provides an excellent fit to super-critical conditions for the pure CO2 system. However, simulating pure-CO2 systems is not sufficient as the super-critical CO2 will co-exist (and interact) with brine present in the saline aquifers. In effect this means that we need to simulate multi-component systems: one phase being the super-critical CO2, the other phase being a brine of varying salinity. Previously, we have used used a Shan-Chen-type model (Shan Chen, 1993, 1994) as modified by Martys and Chen (1996) for simplified capillari pressure dominated air-water systems in porous media

  6. Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization.

    Science.gov (United States)

    Knutson, Thomas R.; Tuleya, Robert E.

    2004-09-01

    Previous studies have found that idealized hurricanes, simulated under warmer, high-CO2 conditions, are more intense and have higher precipitation rates than under present-day conditions. The present study explores the sensitivity of this result to the choice of climate model used to define the CO2-warmed environment and to the choice of convective parameterization used in the nested regional model that simulates the hurricanes. Approximately 1300 five-day idealized simulations are performed using a higher-resolution version of the GFDL hurricane prediction system (grid spacing as fine as 9 km, with 42 levels). All storms were embedded in a uniform 5 m s-1 easterly background flow. The large-scale thermodynamic boundary conditions for the experiments— atmospheric temperature and moisture profiles and SSTs—are derived from nine different Coupled Model Intercomparison Project (CMIP2+) climate models. The CO2-induced SST changes from the global climate models, based on 80-yr linear trends from +1% yr-1 CO2 increase experiments, range from about +0.8° to +2.4°C in the three tropical storm basins studied. Four different moist convection parameterizations are tested in the hurricane model, including the use of no convective parameterization in the highest resolution inner grid. Nearly all combinations of climate model boundary conditions and hurricane model convection schemes show a CO2-induced increase in both storm intensity and near-storm precipitation rates. The aggregate results, averaged across all experiments, indicate a 14% increase in central pressure fall, a 6% increase in maximum surface wind speed, and an 18% increase in average precipitation rate within 100 km of the storm center. The fractional change in precipitation is more sensitive to the choice of convective parameterization than is the fractional change of intensity. Current hurricane potential intensity theories, applied to the climate model environments, yield an average increase of intensity

  7. Modeled responses of terrestrial ecosystems to elevated atmospheric CO2: A comparison of simulations by the biogeochemistry models of the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP)

    Science.gov (United States)

    Pan, Y.; Melillo, J.M.; McGuire, A.D.; Kicklighter, D.W.; Pitelka, L.F.; Hibbard, K.; Pierce, L.L.; Running, S.W.; Ojima, D.S.; Parton, W.J.; Schimel, D.S.; Borchers, J.; Neilson, R.; Fisher, H.H.; Kittel, T.G.F.; Rossenbloom, N.A.; Fox, S.; Haxeltine, A.; Prentice, I.C.; Sitch, S.; Janetos, A.; McKeown, R.; Nemani, R.; Painter, T.; Rizzo, B.; Smith, T.; Woodward, F.I.

    1998-01-01

    Although there is a great deal of information concerning responses to increases in atmospheric CO2 at the tissue and plant levels, there are substantially fewer studies that have investigated ecosystem-level responses in the context of integrated carbon, water, and nutrient cycles. Because our understanding of ecosystem responses to elevated CO2 is incomplete, modeling is a tool that can be used to investigate the role of plant and soil interactions in the response of terrestrial ecosystems to elevated CO2. In this study, we analyze the responses of net primary production (NPP) to doubled CO2 from 355 to 710 ppmv among three biogeochemistry models in the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP): BIOME-BGC (BioGeochemical Cycles), Century, and the Terrestrial Ecosystem Model (TEM). For the conterminous United States, doubled atmospheric CO2 causes NPP to increase by 5% in Century, 8% in TEM, and 11% in BIOME-BGC. Multiple regression analyses between the NPP response to doubled CO2 and the mean annual temperature and annual precipitation of biomes or grid cells indicate that there are negative relationships between precipitation and the response of NPP to doubled CO2 for all three models. In contrast, there are different relationships between temperature and the response of NPP to doubled CO2 for the three models: there is a negative relationship in the responses of BIOME-BGC, no relationship in the responses of Century, and a positive relationship in the responses of TEM. In BIOME-BGC, the NPP response to doubled CO2 is controlled by the change in transpiration associated with reduced leaf conductance to water vapor. This change affects soil water, then leaf area development and, finally, NPP. In Century, the response of NPP to doubled CO2 is controlled by changes in decomposition rates associated with increased soil moisture that results from reduced evapotranspiration. This change affects nitrogen availability for plants, which influences NPP. In

  8. System-level modeling for geological storage of CO2

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-04-24

    One way to reduce the effects of anthropogenic greenhousegases on climate is to inject carbon dioxide (CO2) from industrialsources into deep geological formations such as brine formations ordepleted oil or gas reservoirs. Research has and is being conducted toimprove understanding of factors affecting particular aspects ofgeological CO2 storage, such as performance, capacity, and health, safetyand environmental (HSE) issues, as well as to lower the cost of CO2capture and related processes. However, there has been less emphasis todate on system-level analyses of geological CO2 storage that considergeological, economic, and environmental issues by linking detailedrepresentations of engineering components and associated economic models.The objective of this study is to develop a system-level model forgeological CO2 storage, including CO2 capture and separation,compression, pipeline transportation to the storage site, and CO2injection. Within our system model we are incorporating detailedreservoir simulations of CO2 injection and potential leakage withassociated HSE effects. The platform of the system-level modelingisGoldSim [GoldSim, 2006]. The application of the system model is focusedon evaluating the feasibility of carbon sequestration with enhanced gasrecovery (CSEGR) in the Rio Vista region of California. The reservoirsimulations are performed using a special module of the TOUGH2 simulator,EOS7C, for multicomponent gas mixtures of methane and CO2 or methane andnitrogen. Using this approach, the economic benefits of enhanced gasrecovery can be directly weighed against the costs, risks, and benefitsof CO2 injection.

  9. 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

  10. X-ray CT analyses, models and numerical simulations: a comparison with petrophysical analyses in an experimental CO2 study

    Science.gov (United States)

    Henkel, Steven; Pudlo, Dieter; Enzmann, Frieder; Reitenbach, Viktor; Albrecht, Daniel; Ganzer, Leonhard; Gaupp, Reinhard

    2016-06-01

    An essential part of the collaborative research project H2STORE (hydrogen to store), which is funded by the German government, was a comparison of various analytical methods for characterizing reservoir sandstones from different stratigraphic units. In this context Permian, Triassic and Tertiary reservoir sandstones were analysed. Rock core materials, provided by RWE Gasspeicher GmbH (Dortmund, Germany), GDF Suez E&P Deutschland GmbH (Lingen, Germany), E.ON Gas Storage GmbH (Essen, Germany) and RAG Rohöl-Aufsuchungs Aktiengesellschaft (Vienna, Austria), were processed by different laboratory techniques; thin sections were prepared, rock fragments were crushed and cubes of 1 cm edge length and plugs 3 to 5 cm in length with a diameter of about 2.5 cm were sawn from macroscopic homogeneous cores. With this prepared sample material, polarized light microscopy and scanning electron microscopy, coupled with image analyses, specific surface area measurements (after Brunauer, Emmet and Teller, 1938; BET), He-porosity and N2-permeability measurements and high-resolution microcomputer tomography (μ-CT), which were used for numerical simulations, were applied. All these methods were practised on most of the same sample material, before and on selected Permian sandstones also after static CO2 experiments under reservoir conditions. A major concern in comparing the results of these methods is an appraisal of the reliability of the given porosity, permeability and mineral-specific reactive (inner) surface area data. The CO2 experiments modified the petrophysical as well as the mineralogical/geochemical rock properties. These changes are detectable by all applied analytical methods. Nevertheless, a major outcome of the high-resolution μ-CT analyses and following numerical data simulations was that quite similar data sets and data interpretations were maintained by the different petrophysical standard methods. Moreover, the μ-CT analyses are not only time saving, but also non

  11. 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

  12. Simulating the budget and distribution of Δ17O in CO2 with a global atmosphere-biosphere model

    NARCIS (Netherlands)

    Peters, Wouter; Schneider, Linda; Hofmann, Magdalena E. G.; van der Velde, Ivar; Röckmann, Thomas

    2015-01-01

    The isotope ratios of 16O, 17O and 18O in CO2 are referred to as the triple-oxygen isotope composition of CO2, and have long held promise to better understand terrestrial carbon cycling. However, measurement precision as well as an incomplete understanding of fractionation during equilibrium

  13. Simulation Studies of Satellite Laser CO2 Mission Concepts

    Science.gov (United States)

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

    2011-01-01

    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. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudodata" CO2. 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.

  14. A test of sensitivity to convective transport in a global atmospheric CO2 simulation

    OpenAIRE

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

    2011-01-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. Global CO2 in the year 2000 is simulated using the CTM 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...

  15. 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

  16. 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, W. M.; Pawson, S.; Collatz, G. J.; Gregg, W. W.

    2012-12-01

    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 downscaled 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

  17. 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 t

  18. Sensitivity of simulated CO2 concentration to sub-annual variations in fossil fuel CO2 emissions

    Science.gov (United States)

    Zhang, X.; Gurney, K. R.; Rayner, P. J.; Baker, D. F.; Liu, Y.; Asefi-Najafabady, S.

    2014-12-01

    This study presents a sensitivity analysis of the impact of sub-annual fossil fuel CO2 emissions on simulated CO2 concentration using a global tracer transport model. Four sensitivity experiments were conducted to investigate the impact of three cyclic components (diurnal, weekly and monthly) and a complete cyclic component (the combination of the three) by comparing with a temporally "flat" fossil fuel CO2 emissions inventory. A complete exploration of these impacts is quantified at annual, seasonal, weekly and diurnal time scales of the CO2concentration for the surface, vertical profile and column-integral structure. Result shows an annual mean surface concentration difference varying from -1.35 ppm to 0.13 ppm at grid scale for the complete cyclic fossil fuel emissions, which is mainly driven by a large negative diurnal rectification and less positive seasonal rectification. The negative diurnal rectification is up to 1.45 ppm at grid scale and primarily due to the covariation of diurnal fossil fuel CO2 emissions and diurnal variations of vertical mixing. The positive seasonal rectification is up to 0.23 ppm at grid scale which is mainly driven by the monthly fossil fuel CO2emissions coupling with atmospheric transport. Both the diurnal and seasonal rectifier effects are indicated at local-to-regional scales with center at large source regions and extend to neighboring regions in mainly Northern Hemisphere. The diurnal fossil fuel CO2 emissions is found to significantly affect the simulated diurnal CO2 amplitude (up to 9.12 ppm at grid scale), which is primarily contributed by the minima concentration differences around local sunset time. Similarly, large impact on the seasonal CO2 amplitude (up to 6.11 ppm) is found at regional scale for the monthly fossil fuel emissions. An impact of diurnal fossil fuel CO2 emissions on simulated afternoon CO2 concentration is also identified by up to 1.13 ppm at local scales. The study demonstrates a large cyclic fossil fuel

  19. 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

  20. Simulating CO2 adsorption and diffusion on a graphite surface

    NARCIS (Netherlands)

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

    2013-01-01

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

  1. Global high-resolution simulations of CO2 and CH4 using a NIES transport model to produce a priori concentrations for use in satellite data retrievals

    Directory of Open Access Journals (Sweden)

    S. Maksyutov

    2013-01-01

    Full Text Available The Greenhouse gases Observing SATellite (GOSAT measures column-averaged dry air mole fractions of carbon dioxide and methane (XCO2 and XCH4, respectively. Since the launch of GOSAT, model-simulated three-dimensional concentrations from a National Institute for Environmental Studies offline tracer Transport Model (NIES TM have been used as a priori concentration data for operational near real-time retrievals of XCO2 and XCH4 from GOSAT short-wavelength infrared spectra at NIES. Although the choice of a priori profile has only a minor effect on retrieved XCO2 or XCH4, a realistic simulation with minimal deviation from observed data is desirable. In this paper, we describe the newly developed version of NIES TM that has been adapted to provide global and near real-time concentrations of CO2 and CH4 using a high-resolution meteorological dataset, the Grid Point Value (GPV prepared by the Japan Meteorological Agency. The spatial resolution of the NIES TM is set to 0.5° × 0.5° in the horizontal in order to utilise GPV data, which have a resolution of 0.5° × 0.5°, 21 pressure levels and a time interval of 3 h. GPV data are provided to the GOSAT processing system with a delay of several hours, and the near real-time model simulation produces a priori concentrations driven by diurnally varying meteorology. A priori variance–covariance matrices of CO2 and CH4 are also derived from the simulation outputs and observation-based reference data for each month of the year at a resolution of 0.5° × 0.5° and 21 pressure levels. Model performance is assessed by comparing simulation results with the GLOBALVIEW dataset and other observational data. The overall root-mean-square differences between model predictions and GLOBALVIEW analysis are estimated to be 1.45 ppm and 12.52 ppb for CO2 and CH4, respectively, and the seasonal correlation coefficients are 0.87 for CO2 and 0.53 for CH4. The model showed good performance particularly at oceanic and free

  2. 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.

  3. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Energy Technology Data Exchange (ETDEWEB)

    Nassar, Ray [University of Toronto; Jones, DBA [University of Toronto; Suntharalingam, P [University of East Anglia, Norwich, United Kingdom; Chen, j. [University of Toronto; Andres, Robert Joseph [ORNL; Wecht, K. J. [Harvard University; Yantosca, R. M. [Harvard University; Kulawik, SS [Jet Propulsion Laboratory, Pasadena, CA; Bowman, K [Jet Propulsion Laboratory, Pasadena, CA; Worden, JR [Jet Propulsion Laboratory, Pasadena, CA; Machida, T [National Institute for Environmental Studies, Japan; Matsueda, H [Meteorological Research Institute, Japan

    2010-01-01

    The use of global three-dimensional (3-D) models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth s carbon cycle. Here we use the GEOS-Chem model (version 8-02-01) CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (0.19 PgC yr 1), 3-D spatially-distributed emissions from aviation (0.16 PgC yr 1), and 3-D chemical production of CO2 (1.05 PgC yr 1). Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon) and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (3%), while the inclusion of CO2 chemical production (and the surface correction) is shown to decrease the latitudinal gradient by about 0.40 ppm (10%) with a complex spatial structure

  4. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species

    Directory of Open Access Journals (Sweden)

    K. W. Bowman

    2010-12-01

    Full Text Available The use of global three-dimensional (3-D models with satellite observations of CO2 in inverse modeling studies is an area of growing importance for understanding Earth's carbon cycle. Here we use the GEOS-Chem model (version 8-02-01 CO2 mode with multiple modifications in order to assess their impact on CO2 forward simulations. Modifications include CO2 surface emissions from shipping (~0.19 Pg C yr−1, 3-D spatially-distributed emissions from aviation (~0.16 Pg C yr−1, and 3-D chemical production of CO2 (~1.05 Pg C yr−1. Although CO2 chemical production from the oxidation of CO, CH4 and other carbon gases is recognized as an important contribution to global CO2, it is typically accounted for by conversion from its precursors at the surface rather than in the free troposphere. We base our model 3-D spatial distribution of CO2 chemical production on monthly-averaged loss rates of CO (a key precursor and intermediate in the oxidation of organic carbon and apply an associated surface correction for inventories that have counted emissions of CO2 precursors as CO2. We also explore the benefit of assimilating satellite observations of CO into GEOS-Chem to obtain an observation-based estimate of the CO2 chemical source. The CO assimilation corrects for an underestimate of atmospheric CO abundances in the model, resulting in increases of as much as 24% in the chemical source during May–June 2006, and increasing the global annual estimate of CO2 chemical production from 1.05 to 1.18 Pg C. Comparisons of model CO2 with measurements are carried out in order to investigate the spatial and temporal distributions that result when these new sources are added. Inclusion of CO2 emissions from shipping and aviation are shown to increase the global CO2 latitudinal gradient by just over 0.10 ppm (~3%, while the inclusion of CO2 chemical production (and the surface correction is shown to decrease the latitudinal gradient by about 0.40 ppm (~10% with a complex

  5. Numerical Simulation of Natural Convection in Heterogeneous Porous media for CO2 Geological Storage

    NARCIS (Netherlands)

    Ranganathan, P.; Farajzadeh, R.; Bruining, J.; Zitha, P.L.J.

    2012-01-01

    We report a modeling and numerical simulation study of density-driven natural convection during geological CO2 storage in heterogeneous formations. We consider an aquifer or depleted oilfield overlain by gaseous CO2, where the water density increases due to CO2 dissolution. The heterogeneity of the

  6. Effects of dissolved CO2 on Shallow Freshwater Microbial Communities simulating a CO2 Leakage Scenario

    Science.gov (United States)

    Gulliver, D. M.; Lowry, G. V.; Gregory, K.

    2013-12-01

    Geological carbon sequestration is likely to be part of a comprehensive strategy to minimize the atmospheric release of greenhouse gasses, establishing a concern of sequestered CO2 leakage into overlying potable aquifers. Leaking CO2 may affect existing biogeochemical processes and therefore water quality. There is a critical need to understand the evolution of CO2 exposed microbial communities that influence the biogeochemistry in these freshwater aquifers. The evolution of microbial ecology for different CO2 exposure concentrations was investigated using fluid-slurry samples obtained from a shallow freshwater aquifer (55 m depth, 0.5 MPa, 22 °C, Escatawpa, MS). The microbial community of well samples upstream and downstream of CO2 injection was characterized. In addition, batch vessel experiments were conducted with the upstream aquifer samples exposed to varying pCO2 from 0% to 100% under reservoir temperature and pressure for up to 56 days. The microbial community of the in situ experiment and the batch reactor experiment were analyzed with 16S rRNA clone libraries and qPCR. In both the in situ experiment and the batch reactor experiment, DNA concentration did not correlate with CO2 exposure. Both the in situ experiment and the batch reactors displayed a changing microbial community with increased CO2 exposure. The well water isolate, Curvibacter, appeared to be the most tolerant genus to high CO2 concentrations in the in situ experiments and to mid-CO2 concentrations in the batch reactors. In batch reactors with pCO2 concentrations higher than experienced in situ (pCO2 = 0.5 MPa), Pseudomonas appeared to be the most tolerant genus. Findings provide insight into a dynamic biogeochemical system that will alter with CO2 exposure. Adapted microbial populations will eventually give rise to the community that will impact the metal mobility and water quality. Knowledge of the surviving microbial populations will enable improved models for predicting the fate of CO2

  7. 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.

  8. 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

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

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-02-01

    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.

  10. 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.

  11. Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models

    Directory of Open Access Journals (Sweden)

    M. Lawrence

    2012-06-01

    Full Text Available In this study we compare the response of four state-of-the-art Earth system models to climate engineering under scenario G1 of two model intercomparison projects: GeoMIP (Geoengineering Model Intercomparison Project and IMPLICC (EU project "Implications and risks of engineering solar radiation to limit climate change". In G1, the radiative forcing from an instantaneous quadrupling of the CO2 concentration, starting from the preindustrial level, is balanced by a reduction of the solar constant. Model responses to the two counteracting forcings in G1 are compared to the preindustrial climate in terms of global means and regional patterns and their robustness. While the global mean surface air temperature in G1 remains almost unchanged compared to the control simulation, the meridional temperature gradient is reduced in all models. Another robust response is the global reduction of precipitation with strong effects in particular over North and South America and northern Eurasia. In comparison to the climate response to a quadrupling of CO2 alone, the temperature responses are small in experiment G1. Precipitation responses are, however, in many regions of comparable magnitude but globally of opposite sign.

  12. Mesoscale modelling of atmospheric CO2 across Denmark

    DEFF Research Database (Denmark)

    Lansø, Anne Sofie

    2016-01-01

    of the simulated atmospheric CO2 across Denmark was, in particular, affected by the Danish terrestrial surface exchanges and its temporal variability. This study urges all future modelling studies of air–sea CO2 to include short-term variability in pCO2. To capture the full heterogeneity of the surface exchanges......It is scientifically well-established that the increase of atmospheric CO2 affects the entire globe and will lead to higher surface temperatures. Although anthropogenic CO2is emitted straight into the atmosphere, it does not all contribute to the existing atmospheric CO2 reservoir. Approximately 29......% is taken up by the global oceans, due to under-saturation of CO2 in the surface waters, while another 33 % is taken up by the terrestrial biosphere, via photosynthesis. In order to estimate the effects of increasing anthropogenic emissions of CO2 more accurately in the future, it is essential to understand...

  13. Thermodynamic modeling of CO2 mixtures

    DEFF Research Database (Denmark)

    Bjørner, Martin Gamel

    performed satisfactorily and predicted the general behavior of the systems, but qCPA used fewer adjustable parameters to achieve similar predictions. It has been demonstrated that qCPA is a promising model which, compared to CPA, systematically improves the predictions of the experimentally determined phase......, 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...... do not explicitly account for. In this thesis, in an attempt to obtain a physically more consistent model, the cubicplus association (CPA) EoS is extended to include quadrupolar interactions. The new quadrupolar CPA (qCPA) can be used with the experimental value of the quadrupolemoment...

  14. Method for tracing simulated CO2 leak in terrestrial environment with a 13CO2 tracer

    Science.gov (United States)

    Moni, Christophe; Rasse, Daniel

    2013-04-01

    Facilities for the geological storage of carbon dioxide (CO2) as part of carbon capture and storage (CCS) schemes will be designed to prevent any leakage from the defined 'storage complex'. However, developing regulations and guidance throughout the world (e.g. the EC Directive and the USEPA Vulnerability Evaluation Framework) recognize the importance of assessing the potential for environmental impacts from CO2 storage. RISCS, a European (FP7) project, aims to improve understanding of those impacts that could plausibly occur in the hypothetical case that unexpected leakage occurs. As part of the RISCS project the potential impacts that an unexpected CO2 leaks might have on a cropland ecosystems was investigated. A CO2 exposure field experiment based on CO2 injection at 85 cm depth under an oats culture was designed. To facilitate the characterization of the simulated leaking zone the gas used for injection was produced from natural gas and had a δ13C of -46‰. The aim of the present communication is to depict how the injected gas was traced within the soil-vegetation-atmosphere continuum using 13CO2 continuous cavity ring-down spectrometry (CRDS). Four subsurface experimental injection plots (6m x 3m) were set up. In order to test the effects of different intensity of leakage, the field experiment was designed as to create a longitudinal CO2 gradient for each plot. For this purpose gas supply pipes were inserted at one extremity of each plot at the base of a 45 cm thick layer of sand buried 40 cm below the surface under the clayey plough layer of Norwegian moraine soils. Soil CO2 concentration and isotopic signature were punctually recorded: 1) in the soil at 20 cm depth at 6 positions distributed on the central transect, 2) at the surface following a (50x50 cm) grid sampling pattern, and 3) in the canopy atmosphere at 10, 20, 30 cm along three longitudinal transects (seven sampling point per transect). Soil CO2 fluxes and isotopic signature were finally

  15. Natural variability of CO2 and O2 fluxes: What can we learn from centuries-long climate models simulations?

    Science.gov (United States)

    Resplandy, L.; Séférian, R.; Bopp, L.

    2015-01-01

    carbon uptake and oxygen content estimates over the past decades suggest that the anthropogenic carbon sink has changed and that the oxygen concentration in the ocean interior has decreased. Although these detected changes appear consistent with those expected from anthropogenic forced climate change, large uncertainties remain in the contribution of natural variability. Using century-long simulations (500-1000 years) of unforced natural variability from six Earth System Models (ESMs), we examine the internally driven natural variability of carbon and oxygen fluxes from interannual to multidecadal time scales. The intensity of natural variability differs between the ESMs, in particular, decadal variability locally accounts for 10-50% of the total variance. Although the variability is higher in all regions with strong climate modes (North Atlantic, North Pacific, etc.), we find that only the Southern Ocean and the tropical Pacific significantly modulate the global fluxes. On (multi)decadal time scales, deep convective events along the Antarctic shelf drive the global fluxes variability by transporting deep carbon-rich/oxygen-depleted waters to the surface and by reducing the sea-ice coverage. On interannual time scales, the global flux is modulated by (1) variations of the upwelling of circumpolar deep waters associated with the southern annular mode in the subpolar Southern Ocean and (2) variations of the equatorial/costal upwelling combined with changes in the solubility-driven fluxes in response to El Niño Southern Oscillation (ENSO) in the tropical Pacific. We discuss the challenges of measuring and detecting long-term trends from a few decade-long records influenced by internal variability.

  16. Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and 14CO2 measurements: Observation System Simulations

    Science.gov (United States)

    Basu, Sourish; Bharat Miller, John; Lehman, Scott

    2016-05-01

    National annual total CO2 emissions from combustion of fossil fuels are likely known to within 5-10 % for most developed countries. However, uncertainties are inevitably larger (by unknown amounts) for emission estimates at regional and monthly scales, or for developing countries. Given recent international efforts to establish emission reduction targets, independent determination and verification of regional and national scale fossil fuel CO2 emissions are likely to become increasingly important. Here, we take advantage of the fact that precise measurements of 14C in CO2 provide a largely unbiased tracer for recently added fossil-fuel-derived CO2 in the atmosphere and present an atmospheric inversion technique to jointly assimilate observations of CO2 and 14CO2 in order to simultaneously estimate fossil fuel emissions and biospheric exchange fluxes of CO2. Using this method in a set of Observation System Simulation Experiments (OSSEs), we show that given the coverage of 14CO2 measurements available in 2010 (969 over North America, 1063 globally), we can recover the US national total fossil fuel emission to better than 1 % for the year and to within 5 % for most months. Increasing the number of 14CO2 observations to ˜ 5000 per year over North America, as recently recommended by the National Academy of Science (NAS) (Pacala et al., 2010), we recover monthly emissions to within 5 % for all months for the US as a whole and also for smaller, highly emissive regions over which the specified data coverage is relatively dense, such as for the New England states or the NY-NJ-PA tri-state area. This result suggests that, given continued improvement in state-of-the art transport models, a measurement program similar in scale to that recommended by the NAS can provide for independent verification of bottom-up inventories of fossil fuel CO2 at the regional and national scale. In addition, we show that the dual tracer inversion framework can detect and minimize biases in

  17. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    Science.gov (United States)

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-06

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.

  18. Capillary filling rules and displacement mechanisms for spontaneous imbibition of CO2 for carbon storage and EOR using micro-model experiments and pore scale simulation

    Science.gov (United States)

    Chapman, E.; Yang, J.; Crawshaw, J.; Boek, E. S.

    2012-04-01

    In the 1980s, Lenormand et al. carried out their pioneering work on displacement mechanisms of fluids in etched networks [1]. Here we further examine displacement mechanisms in relation to capillary filling rules for spontaneous imbibition. Understanding the role of spontaneous imbibition in fluid displacement is essential for refining pore network models. Generally, pore network models use simple capillary filling rules and here we examine the validity of these rules for spontaneous imbibition. Improvement of pore network models is vital for the process of 'up-scaling' to the field scale for both enhanced oil recovery (EOR) and carbon sequestration. In this work, we present our experimental microfluidic research into the displacement of both supercritical CO2/deionised water (DI) systems and analogous n-decane/air - where supercritical CO2 and n-decane are the respective wetting fluids - controlled by imbibition at the pore scale. We conducted our experiments in etched PMMA and silicon/glass micro-fluidic hydrophobic chips. We first investigate displacement in single etched pore junctions, followed by displacement in complex network designs representing actual rock thin sections, i.e. Berea sandstone and Sucrosic dolomite. The n-decane/air experiments were conducted under ambient conditions, whereas the supercritical CO2/DI water experiments were conducted under high temperature and pressure in order to replicate reservoir conditions. Fluid displacement in all experiments was captured via a high speed video microscope. The direction and type of displacement the imbibing fluid takes when it enters a junction is dependent on the number of possible channels in which the wetting fluid can imbibe, i.e. I1, I2 and I3 [1]. Depending on the experiment conducted, the micro-models were initially filled with either DI water or air before the wetting fluid was injected. We found that the imbibition of the wetting fluid through a single pore is primarily controlled by the

  19. 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...

  20. 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.

  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)

    F. W. Primeau

    2011-11-01

    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 ΔC* method, and two are based on reconstructions of the Green function for the surface-to-interior transport, the TTD method and the maximum entropy inversion method (KPH. The KPH 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 KPH 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 KPH method are generally valid on the global scale, but may introduce significant errors in Cant estimates on regional scales. The KPH method should also be used with caution when predicting future oceanic anthropogenic carbon uptake.

  2. Improving the inter-hemispheric gradient of total column atmospheric CO2 and CH4 in simulations with the ECMWF semi-Lagrangian atmospheric global model

    Science.gov (United States)

    Agusti-Panareda, Anna; Diamantakis, Michail; Bayona, Victor; Klappenbach, Friedrich; Butz, Andre

    2017-01-01

    It is a widely established fact that standard semi-Lagrangian advection schemes are highly efficient numerical techniques for simulating the transport of atmospheric tracers. However, as they are not formally mass conserving, it is essential to use some method for restoring mass conservation in long time range forecasts. A common approach is to use global mass fixers. This is the case of the semi-Lagrangian advection scheme in the Integrated Forecasting System (IFS) model used by the Copernicus Atmosphere Monitoring Service (CAMS) at the European Centre for Medium-Range Weather Forecasts (ECMWF).Mass fixers are algorithms with substantial differences in complexity and sophistication but in general of low computational cost. This paper shows the positive impact mass fixers have on the inter-hemispheric gradient of total atmospheric column-averaged CO2 and CH4, a crucial feature of their spatial distribution. Two algorithms are compared: the simple "proportional" and the more complex Bermejo-Conde schemes. The former is widely used by several Earth system climate models as well the CAMS global forecasts and analysis of atmospheric composition, while the latter has been recently implemented in IFS. Comparisons against total column observations demonstrate that the proportional mass fixer is shown to be suitable for the low-resolution simulations, but for the high-resolution simulations the Bermejo-Conde scheme clearly gives better results. These results have potential repercussions for climate Earth system models using proportional mass fixers as their resolution increases. It also emphasises the importance of benchmarking the tracer mass fixers with the inter-hemispheric gradient of long-lived greenhouse gases using observations.

  3. Numerical Simulation Study on the Impacts of Tropospheric O3 and CO2 Concentration Changes on Winter Wheat.Part Ⅰ: Model Description

    Institute of Scientific and Technical Information of China (English)

    ZHENG Changling; WANG Chunyi

    2006-01-01

    Ozone is well documented as the air pollutant most damaging to agricultural crops and other plants.It is reported that tropospheric O3 concentration increases rapidly in recent 20 years.Evaluating and predicting impacts of ozone concentration changes on crops are drawing great attention in the scientific community. In China, main study method about this filed is controlled experiments, for example, Open Top Chambers. But numerical simulation study about impacts of ozone on crops with crop model was developed slowly, what is more, the study about combined impacts of ozone and carbon dioxide has not been reported.The improved agroecosystem model is presented to evaluate simultaneously impacts of tropospheric O3and CO2 concentration changes on crops in the paper by integrating algorithms about impacts of ozone on photosynthesis with an existing agroecosystem biogeochemical model (named as DNDC). The main physiological processes of crop growth (phenology, leaf area index, photosynthesis, respiration, assimilated allocation and so on) in the former DNDC are kept. The algorithms about impacts of ozone on photosynthesis and winter wheat leaf are added in the modified DNDC model in order to reveal impacts of ozone and carbon dioxide on growth, development, and yield formation of winter wheat by coupling the simulation about impacts of carbon dioxide on photosynthesis of winter wheat which exists in the former DNDC. In the paper, firstly assimilate allocation algorithms and some genetic parameters (such as daily thermal time of every development stage) were modified in order that DNDC can be applicable in North China. Secondly impacts of ozone on crops were simulated with two different methods- one was impacts of ozone on light use efficiency, and the other was direct effects of ozone on leaves photosynthesis. The latter simulated results are closer to experiment measurements through comparing their simulating results. At last the method of direct impacts of ozone on leaf

  4. Process Simulation of Oxy-combustion CO2 Capture in Cement Plant

    OpenAIRE

    2014-01-01

    The objectives of this master thesis have been to model and simulate oxy-combustion CO2 capture in a cement plant. The model developed is a process simulation of the calcination process with varying degree of air in-leakage, where heat is supplied by combustion in an oxygen rich environment, followed by capture of the CO2. The further gas separation after H2O condensation to achieve the required CO2 quality was evaluated. In addition to the process simulations, a review of literature related ...

  5. A cross-association model for CO2-methanol and CO2-ethanol mixtures

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A cross-association model was proposed for CO2-alcohol mixtures based on the statistical associating fluid theory (SAFT).CO2 was treated as a pseudo-associating molecule and both the self-association between alcohol hydroxyls and the cross-association between CO2 and alcohol hydroxyls were considered.The equilibrium properties from low temperature-pressure to high temperature-pressure were investigated using this model.The calculated p-x and p-p diagrams of CO2-methanol and CO2-ethanol mixtures agreed with the experimental data.The results showed that when the cross-association was taken into account for Helmholtz free energy,the calculated equilibrium properties could be significantly improved,and the error prediction of the three phase equilibria and triple points in low temperature regions could be avoided.

  6. 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.

  7. 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.

    2006-11-01

    Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. Global CO2 in the year 2000 is simulated using the CTM 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.

  8. 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)

    This study assesses the ability of 21 crop models to capture the impact of elevated CO2 concentration ([CO218 ]) on maize yield and water use as measured in a 2-year Free Air Carbon dioxide Enrichment experiment conducted at the Thünen Institute in Braunschweig, Germany (Manderscheid et al. 2014). D...

  9. A Field Study on Simulation of CO2 Injection and ECBM Production and Prediction of CO2 Storage Capacity in Unmineable Coal Seam

    Directory of Open Access Journals (Sweden)

    Qin He

    2013-01-01

    Full Text Available CO2 sequestration into a coal seam project was studied and a numerical model was developed in this paper to simulate the primary and secondary coal bed methane production (CBM/ECBM and carbon dioxide (CO2 injection. The key geological and reservoir parameters, which are germane to driving enhanced coal bed methane (ECBM and CO2 sequestration processes, including cleat permeability, cleat porosity, CH4 adsorption time, CO2 adsorption time, CH4 Langmuir isotherm, CO2 Langmuir isotherm, and Palmer and Mansoori parameters, have been analyzed within a reasonable range. The model simulation results showed good matches for both CBM/ECBM production and CO2 injection compared with the field data. The history-matched model was used to estimate the total CO2 sequestration capacity in the field. The model forecast showed that the total CO2 injection capacity in the coal seam could be 22,817 tons, which is in agreement with the initial estimations based on the Langmuir isotherm experiment. Total CO2 injected in the first three years was 2,600 tons, which according to the model has increased methane recovery (due to ECBM by 6,700 scf/d.

  10. 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.

  11. Numerical and analogue modelling of the propagation and dissolution of CO2 into reservoir brines: implications for CO2 sequestration

    Science.gov (United States)

    Daniels, K.; Bickle, M.; Neufeld, J. A.; Waterton, P.; Kampman, N.; Maskell, A.; Chapman, H.

    2013-12-01

    The release of carbon dioxide (CO2) and other greenhouse gases into the atmosphere is recognised as the principal cause of the current changes observed in the Earth's climate. Carbon Capture and Storage (CCS) within reservoirs is seen as a solution to combat these changes through long-term and secure geological storage of CO2. The viability of long-term storage however, is reliant on an accurate knowledge of CO2 trapping mechanisms, as well as an understanding of the effect of the injected supercritical CO2 on the reservoir formations themselves. One prospective stable trapping mechanism is the dissolution of CO2 into ambient reservoir brine. Developing a greater understanding of the flow of CO2 through reservoir rocks and the associated reactions between the host rock formation and the fluid is therefore of great importance to understanding whether a CO2 storage site will succeed. This study examines the enhanced rates of dissolution found during injection into a layered, heterogeneous formation through analogue experiments and numerical modelling. The analogue experiments are designed to approximate an enhanced oil recovery (EOR) setting and show that during fluid propagation, pore-scale viscous fingers grow and retreat. This will provide an increased surface area between the flow and the ambient reservoir fluid which is likely to enhance the dissolution of CO2 in reservoir brines. The numerical simulations provide a useful comparison with the analogue experiments and give constraints on the timescales and magnitude of CO2 dissolution and the resultant fluid-mineral reactions in a heterogeneous reservoir. The study begins to address whether the dissolution of carbonate or silicate minerals can provide the CO2 with a leakage pathway through corroded caprocks and fault seals, or help with pathway sealing.

  12. A Review of CO2-Enhanced Oil Recovery with a Simulated Sensitivity Analysis

    Directory of Open Access Journals (Sweden)

    Mandadige Samintha Anne Perera

    2016-06-01

    Full Text Available This paper reports on a comprehensive study of the CO2-EOR (Enhanced oil recovery process, a detailed literature review and a numerical modelling study. According to past studies, CO2 injection can recover additional oil from reservoirs by reservoir pressure increment, oil swelling, the reduction of oil viscosity and density and the vaporization of oil hydrocarbons. Therefore, CO2-EOR can be used to enhance the two major oil recovery mechanisms in the field: miscible and immiscible oil recovery, which can be further increased by increasing the amount of CO2 injected, applying innovative flood design and well placement, improving the mobility ratio, extending miscibility, and controlling reservoir depth and temperature. A 3-D numerical model was developed using the CO2-Prophet simulator to examine the effective factors in the CO2-EOR process. According to that, in pure CO2 injection, oil production generally exhibits increasing trends with increasing CO2 injection rate and volume (in HCPV (Hydrocarbon pore volume and reservoir temperature. In the WAG (Water alternating gas process, oil production generally increases with increasing CO2 and water injection rates, the total amount of flood injected in HCPV and the distance between the injection wells, and reduces with WAG flood ratio and initial reservoir pressure. Compared to other factors, the water injection rate creates the minimum influence on oil production, and the CO2 injection rate, flood volume and distance between the flood wells have almost equally important influence on oil production.

  13. Effects of CO2 leakage on soil bacterial communities from simulated CO2-EOR areas.

    Science.gov (United States)

    Chen, Fu; Yang, Yongjun; Ma, Yanjun; Hou, Huping; Zhang, Shaoliang; Ma, Jing

    2016-05-18

    CO2-EOR (enhanced oil recovery) has been proposed as a viable option for flooding oil and reducing anthropogenic CO2 contribution to the atmospheric pool. However, the potential risk of CO2 leakage from the process poses a threat to the ecological system. High-throughput sequencing was used to investigate the effects of CO2 emission on the composition and structure of soil bacterial communities. The diversity of bacterial communities notably decreased with increasing CO2 flux. The composition of bacterial communities varied along the CO2 flux, with increasing CO2 flux accompanied by increases in the relative abundance of Bacteroidetes and Firmicutes phyla, but decreases in the relative abundance of Acidobacteria and Chloroflexi phyla. Within the Firmicutes phylum, the genus Lactobacillus increased sharply when the CO2 flux was at its highest point. Alpha and beta diversity analysis revealed that differences in bacterial communities were best explained by CO2 flux. The redundancy analysis (RDA) revealed that differences in bacterial communities were best explained by soil pH values which related to CO2 flux. These results could be useful for evaluating the risk of potential CO2 leakages on the ecosystems associated with CO2-EOR processes.

  14. The role of biological rates in the simulated warming effect on oceanic CO2 uptake

    Science.gov (United States)

    Cao, Long; Zhang, Han

    2017-05-01

    Marine biology plays an important role in the ocean carbon cycle. However, the effect of warming-induced changes in biological rates on oceanic CO2 uptake has been largely overlooked. We use an Earth system model of intermediate complexity to investigate the effect of temperature-induced changes in biological rates on oceanic uptake of atmospheric CO2 and compare it with the effects from warming-induced changes in CO2 solubility and ocean mixing and circulation. Under the representative CO2 concentration pathway RCP 8.5 and its extension, by year 2500, relative to the simulation without warming effect on the ocean carbon cycle, CO2-induced warming reduces cumulative oceanic CO2 uptake by 469 Pg C, of which about 20% is associated with the warming-induced change in marine biological rates. In our simulations, the bulk effect of biological-mediated changes on CO2 uptake is smaller than that mediated by changes in CO2 solubility and ocean mixing and circulation. However, warming-induced changes in individual biological rates, including phytoplankton growth, phytoplankton mortality, and detritus remineralization, are found to affect oceanic CO2 uptake by an amount greater than or comparable to that caused by changes in CO2 solubility and ocean physics. Our simulations, which include only a few temperature-dependent biological processes, demonstrate the important role of biological rates in the oceanic CO2 uptake. In reality, many more complicated biological processes are sensitive to temperature change, and their responses to warming could substantially affect oceanic uptake of atmospheric CO2.

  15. 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 ab...

  16. 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

  17. Molecular Dynamics Simulations of CO2 Formation in Interstellar Ices

    CERN Document Server

    Arasa, Carina; van Dishoeck, Ewine F; Kroes, Geert-Jan

    2013-01-01

    CO2 ice is one of the most abundant components in ice-coated interstellar ices besides H2O and CO, but the most favorable path to CO2 ice is still unclear. Molecular dynamics calculations on the ultraviolet photodissociation of different kinds of CO-H2O ice systems have been performed at 10 K in order to demonstrate that the reaction between CO and an OH molecule resulting from H2O photodissociation through the first excited state is a possible route to form CO2 ice. However, our calculations, which take into account different ice surface models, suggest that there is another product with a higher formation probability ((3.00+-0.07)x10-2), which is the HOCO complex, whereas the formation of CO2 has a probability of only (3.6+-0.7)x10-4. The initial location of the CO is key to obtain reaction and form CO2: the CO needs to be located deep into the ice. The HOCO complex becomes trapped in the cold ice surface in the trans-HOCO minimum because it quickly loses its internal energy to the surrounding ice, preventi...

  18. Simulations of Arctic ozone depletion with current and doubled levels of CO2

    Science.gov (United States)

    Butchart, Neal; Austin, John; Shine, Keith P.

    1994-01-01

    Results from idealized 3-D simulations of a dynamical-radiative-photochemical model of the stratosphere are presented for the Northern Hemisphere winter and spring. For a simulation of a quiescent winter, it is found that with current levels of CO2 only modest polar ozone depletion occurs, consistent with observations. For a second simulation with the same planetary wave amplitudes in the upper troposphere but with doubled CO2, the model predicts a northern hemisphere ozone hole comparable to that observed in Antarctica with almost complete ozone destruction at 20 km. Reasons for the marked difference between the simulations are identified.

  19. Comment on 'improving ecophysiological simulation models to predict the impact of elevated CO(2) concentration on crop productivity' by X. Yin.

    Science.gov (United States)

    Kimball, B A

    2013-08-01

    The recent publication by Yin (2013; Annals of Botany 112: 465-475) referred to in the title above provides an excellent review of modelling approaches to predict the impact of elevated CO2 on crop productivity, as well as on the controversy regarding whether yield responses observed in free-air CO2 enrichment (FACE) experiments are indeed lower than those from chamber-based experiments. However, the wheat experiments in the example of fig. 1 in Yin's paper had a flaw as the control plots lacked blowers that were in the FACE plots, which warmed the FACE plots at night and hastened plant development. This Viewpoint seeks to highlight this fact, and to comment on the relative merits of FACE and enclosure experiments.

  20. Effects of Temperature Rise and Increase in CO2 Concentration on Simulated Wheat Yields in Europe

    NARCIS (Netherlands)

    Nonhebel, Sanderine

    1996-01-01

    A crop-growth-simulation model based on SUCROS87 was used to study effects of temperature rise and increase of atmospheric CO2 concentration on wheat yields in several regions in Europe. The model simulated potential and water-limited crop production (growth with ample supply of nutrients and in the

  1. 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

  2. Density Functional Theory (DFT) simulations of CO2 under shock compression and design of liquid CO2 experiments on Z

    Science.gov (United States)

    Mattsson, T. R.; Shulenburger, L.; Root, S.; Cochrane, K. R.

    2011-03-01

    Quantitative knowledge of the thermo-physical properties of CO2 at high pressure is required to confidently model the structure of gas-giants like Neptune and Uranus and the deep carbon cycle of the earth. DFT based molecular dynamics has been established as a method capable of yielding high fidelity results for many materials, including shocked gases, at high pressure and temperature. We predict the principal Hugoniot for liquid CO2 up to 500GPa. Our simulations also show that the plateau in shock pressure identified by Nellis and co-workers is the result of dissociation. At low temperatures we validate the DFT results by comparing with diffusion Monte Carlo calculations. This allows for a more accurate determination of the initial conditions for the shock experiments. We also describe the design of upcoming flyer-plate experiments on the Z-machine aimed at providing high-precision shock compression data for CO2 between 150 and 600 GPa. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corp. for the US Dept. of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  3. MODELLING CO2 EMISSIONS IMPACTS ON CROATIAN POWER SYSTEM

    Directory of Open Access Journals (Sweden)

    Robert Pašičko

    2010-01-01

    Full Text Available Today's electrical energy landscape is characterized by new challenges such as deregulation, liberalization of energy markets, increased competition, growing demands on security of supply, price insecurities, and demand to cut CO2 emissions. All mentioned challenges are calling for consideration of various options (like nuclear, coal, gas or renewable scenarios and for better understanding of energy systems modelling in order to optimize proper energy mix. Existing models are not sufficient any more and planners will need to think differently in order to face these challenges. European emission trading scheme (EU ETS started in 2005 and it has great influence on power system short term and long term planning. Croatia is obliged to establish a national scheme for trading of greenhouse gas emission allowances from the year 2010, which will be focused on monitoring and reporting only until accession to EU when it will be linked with EU ETS. Thus, for Croatian power system it is very important to analyze possible impacts of CO2 emissions. Analysis presented in this paper was done by two different models: mathematical model, based on short run marginal costs (SRMC, relevant for fuel switch in existing power plant and merit order change and long run marginal costs (LRMC, relevant for new investment decisions; and electricity market simulation model PLEXOS, which was used for modelling Croatian power system during development of the Croatian energy strategy in 2008. Results of the analysis show important impacts that emission trading has on Croatian power system, such as influence of emission price rise on price of electricity and on emission quantity, and changes in power plants output that appear with emission price rise. Breakeven point after which gas power plant becomes more competitive than coal is 62 €/tCO2 for SRMC and 40 €/tCO2 for LRMC. With CO2 prices above 31 €/tCO2 wind is more competitive than gas or coal, which emphasizes

  4. 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...

  5. Simulating global soil-CO2 flux and its response to climate change

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It has been argued that increased soil respiration would become a major atmospheric source of CO2 in the event of global warming. The simple statistical models were developed based on a georeferenced database with 0.5°× 0.5° longitude/latitude resolution to simulate global soil-CO2 fluxes, to investigate climatic effects on these fluxes using sensitivity experiments, and to assess possible responses of soil-CO2 fluxes to various climate change scenarios. The statistical models yield a value of 69 PgC/a of global soil CO2 fluxes for current condition. Sensitivity experiments confirm that the fluxes are responsive to changes in temperature,precipitation and actual evapotranspiration, but increases in temperature and actual evapotranspiration affect soil-CO2 fluxes more than increases in precipitation. Using climatic change projections from four global circulation models, each corresponding to an equilibrium doubling of CO2, it can be found that the largest increases in soil-CO2 fluxes were associated with the boreal and tundra regions. The globally averaged soil-CO2 fluxes were estimated to increase by about 35 % above current values, providing a positive feedback to the greenhouse effect.

  6. Simulating global soil-CO2 flux and its response to climate change

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It has been argued that increased soil respiration would become a major atmospheric source of CO2 in the event of global warming. The simple statistical models were developed based on a georeferenced database with 0.5° × 0.5° longitude/latitude resolution to simulate global soil-CO2 fluxes, to investigate climatic effects on these fluxes using sensitivity experiments, and to assess possible responses of soil-CO2 fluxes to various climate change scenarios. The statistical models yield a value of 69 PgC/a of global soil CO2 fluxes for current condition. Sensitivity experiments confirm that the fluxes are responsive to changes in temperature,precipitation and actual evapotranspiration, but increases in temperature and actual evapotranspiration affect soil-CO2 fluxes more than increases in precipitation. Using climatic change projections from four global circulation models, each corresponding to an equilibrium doubling of CO2, it can be found that the largest increases in soil-CO2 fluxes were associated with the boreal and tundra regions. The globally averaged soil-CO2 fluxes were estimated to increase by about 35 % above current values, providing a positive feedback to the greenhouse effect.

  7. Comparison of CO2 fluxes estimated using atmospheric and oceanic inversions, and role of fluxes and their interannual variability in simulating atmospheric CO2 concentrations

    Science.gov (United States)

    Patra, P. K.; Mikaloff Fletcher, S. E.; Ishijima, K.; Maksyutov, S.; Nakazawa, T.

    2006-07-01

    We use a time-dependent inverse (TDI) model to estimate regional sources and sinks of atmospheric CO2 from 64 and then 22 regions based on atmospheric CO2 observations at 87 stations. The air-sea fluxes from the 64-region atmospheric-CO2 inversion are compared with fluxes from an analogous ocean inversion that uses ocean interior observations of dissolved inorganic carbon (DIC) and other tracers and an ocean general circulation model (OGCM). We find that, unlike previous atmospheric inversions, our flux estimates in the southern hemisphere are generally in good agreement with the results from the ocean inversion, which gives us added confidence in our flux estimates. In addition, a forward tracer transport model (TTM) is used to simulate the observed CO2 concentrations using (1) estimates of fossil fuel emissions and a priori estimates of the terrestrial and oceanic fluxes of CO2, and (2) two sets of TDI model corrected fluxes. The TTM simulations of TDI model corrected fluxes show improvements in fitting the observed interannual variability in growth rates and seasonal cycles in atmospheric CO2. Our analysis suggests that the use of interannually varying (IAV) meteorology and a larger observational network have helped to capture the regional representation and interannual variabilities in CO2 fluxes realistically.

  8. Lagrangian simulation of deposition of CO2 gas-solid sudden expansion flow

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Freezing and blockage resulting from the deposition of solid CO2 formed because of sudden expansion of the downstream pipe during the release of CO2 through safety valves,will endanger the protected equipment.To overcome this problem,the characteristics of the CO2 gas-solid sudden expansion flow are studied by using the disperse Lagrangian model.A comparison of the calculated deposition of the solid CO2 with the experimental results shows that they are in reasonable agreement.The simulation results show that the size of the solid CO2 formed should not be in the range of 0.04-0.07 mm (St number 3.2-9.8).This can be achieved by using an appropriate flow cross section of the safety valve.

  9. Elevated CO2 and the Sensitivity of Simulated Crop Yield to Variability in Climate

    Science.gov (United States)

    King, A. W.; Absar, M.; Surendran Nair, S.; Preston, B. L.

    2013-12-01

    It is known that the response of crop yields to elevated carbon dioxide (CO2) concentrations ('CO2 fertilization') can vary with climatic conditions (e.g., precipitation and soil moisture). Likewise, the sensitivity of crop yield to changes in climate may vary with atmospheric CO2 concentrations. The latter is an important consideration when extrapolating crop sensitivities derived from historical climate variability to a future world with higher levels of atmospheric CO2. Here we report on our investigation of how climate sensitivity of model simulated crop yield is influenced by rising and elevated CO2. Initial results from the EPIC crop model for simulated cotton yield at a site in southeastern Texas show very little if any difference in sensitivity to annual precipitation with static versus rising CO2 concentrations. These model results are consistent with experimental results from the Maricopa, Arizona Free Air CO2 Enrichment (FACE) experiment in which there was little or no difference in the productivity response of cotton under ample versus limited supplies of water. This contrasts with experimental results for wheat and sorghum, especially sorghum, in which the response to elevated CO2 was larger when water supply was limited. We report on the interaction between CO2 and the sensitivity of yield to climate with comparisons for different crops, between the EPIC and DSSAT crop models, across different indices of climate change, and between wet and dry climatic domains of the southern United States of America. This investigation is part of our ongoing effort better understand the sensitivity of crop yield to climate in order to inform regional integrated assessment modeling and considerations of adaption to climate change in the Gulf Coastal region of the southern United States.

  10. 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.

  11. 3D modelling of the early Martian Climate under a denser CO2 atmosphere: Temperatures and CO2 ice clouds

    CERN Document Server

    Forget, Francois; Millour, Ehouarn; Madeleine, Jean-Baptiste; Kerber, Laura; Leconte, Jeremy; Marcq, Emmanuel; Haberle, Robert M

    2012-01-01

    On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations of the early martian climate performed assuming a faint young sun and a CO2 atmosphere with pressure between 0.1 and 7 bars. The model includes a detailed radiative transfer model using revised CO2 gas collision induced absorption properties, and a parameterisation of the CO2 ice cloud microphysical and radiative properties. A wide range of possible climates is explored by using various values of obliquities, orbital parameters, cloud microphysic parameters, atmospheric dust loading, and surface properties. Unlike on present day Mars, for pressures higher than a fraction of a bar, surface temperatures vary with altitude because of the adiabatic cooling and warming of the atmosphere when it moves vertically. In most simulations, CO2 ice clouds cover a major part of the planet...

  12. A simple model of the anthropogenically forced CO2 cycle

    Directory of Open Access Journals (Sweden)

    W. Weber

    2015-10-01

    Full Text Available From basic physical assumptions we derive a simple linear model of the global CO2 cycle without free parameters. It yields excellent agreement with the observations reported by the carbon dioxide information analysis center (CDIAC as time series of atmospheric CO2 growth, of sinks in the ocean and of absorption by the biosphere. The agreement extends from the year 1850 until present (2013. Based on anthropogenic CO2 emission scenarios until 2150, future atmospheric CO2 concentrations are calculated. As the model shows, and depending on the emission scenario, the airborne fraction of CO2 begins to decrease in the year ~ 2050 and becomes negative at the latest in ~ 2130. At the same time the concentration of the atmospheric CO2 will reach a maximum between ~ 500 and ~ 900 ppm. As a consequence, increasing anthropogenic CO2 emissions will make the ocean and the biosphere the main reservoirs of anthropogenic CO2 in the long run. Latest in about 150 years, anthropogenic CO2 emission will no longer increase the CO2 content of the atmosphere.

  13. A simple model of the anthropogenically forced CO2 cycle

    Science.gov (United States)

    Weber, W.; Lüdecke, H.-J.; Weiss, C. O.

    2015-10-01

    From basic physical assumptions we derive a simple linear model of the global CO2 cycle without free parameters. It yields excellent agreement with the observations reported by the carbon dioxide information analysis center (CDIAC) as time series of atmospheric CO2 growth, of sinks in the ocean and of absorption by the biosphere. The agreement extends from the year 1850 until present (2013). Based on anthropogenic CO2 emission scenarios until 2150, future atmospheric CO2 concentrations are calculated. As the model shows, and depending on the emission scenario, the airborne fraction of CO2 begins to decrease in the year ~ 2050 and becomes negative at the latest in ~ 2130. At the same time the concentration of the atmospheric CO2 will reach a maximum between ~ 500 and ~ 900 ppm. As a consequence, increasing anthropogenic CO2 emissions will make the ocean and the biosphere the main reservoirs of anthropogenic CO2 in the long run. Latest in about 150 years, anthropogenic CO2 emission will no longer increase the CO2 content of the atmosphere.

  14. 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.

  15. Modeling CO2 air dispersion from gas driven lake eruptions

    Science.gov (United States)

    Chiodini, Giovanni; Costa, Antonio; Rouwet, Dmitri; Tassi, Franco

    2016-04-01

    The most tragic event of gas driven lake eruption occurred at Lake Nyos (Cameroon) on 21 August 1986, when a dense cloud of CO2 suffocated more than 1700 people and an uncounted number of animals in just one night. The event stimulated a series of researches aimed to understand gas origins, gas release mechanisms and strategies for gas hazard mitigation. Very few studies have been carried out for describing the transport of dense CO2 clouds in the atmosphere. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used a model based on a shallow layer approach (TWODEE2). This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of computational fluid dynamic models and the simpler integral models. Recently the model has been applied for simulating CO2 dispersion from natural gas emissions in Central Italy. The results have shown how the dispersion pattern is strongly affected by the intensity of gas release, the topography and the ambient wind speed. Here for the first time we applied TWODEE2 code to simulate the dispersion of the large CO2 clouds released by limnic eruptions. An application concerns the case of the 1986 event at lake Nyos. Some difficulties for the simulations were related to the lack of quantitative information: gas flux estimations are not well constrained, meteorological conditions are only qualitatively known, the digital model of the terrain is of poor quality. Different scenarios were taken into account in order to reproduce the qualitative observations available for such episode. The observations regard mainly the effects of gas on

  16. 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.

  17. Simulation of muon radiography for monitoring CO$_2$ stored in a geological reservoir

    CERN Document Server

    Klinger, J; Coleman, M; Gluyas, J G; Kudryavtsev, V A; Lincoln, D L; Pal, S; Paling, S M; Spooner, N J C; Telfer, S; Thompson, L F; Woodward, D

    2015-01-01

    Current methods of monitoring subsurface CO$_2$, such as repeat seismic surveys, are episodic and require highly skilled personnel to acquire the data. Simulations based on simplified models have previously shown that muon radiography could be automated to continuously monitor CO$_2$ injection and migration, in addition to reducing the overall cost of monitoring. In this paper, we present a simulation of the monitoring of CO$_2$ plume evolution in a geological reservoir using muon radiography. The stratigraphy in the vicinity of a nominal test facility is modelled using geological data, and a numerical fluid flow model is used to describe the time evolution of the CO$_2$ plume. A planar detection region with a surface area of 1000 m$^2$ is considered, at a vertical depth of 776 m below the seabed. We find that one year of constant CO$_2$ injection leads to changes in the column density of $\\lesssim 1\\%$, and that the CO$_2$ plume is already resolvable with an exposure time of less than 50 days.

  18. A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies

    DEFF Research Database (Denmark)

    Ibrom, A.; Jarvis, P.G.; Clement, R.

    2006-01-01

    Gross canopy photosynthesis (Pg) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to si...

  19. Simulation of CO2-Distribution in Fractured Oil Reservoir

    OpenAIRE

    Furuvik, Nora; Halvorsen, Britt

    2015-01-01

    Deep geologic injections and storage of Carbon dioxide (CO2) for enhanced oil recovery (EOR) are an upcoming combination due to the potential for increased oil production from depleted oilfields at the same time reducing the carbon footprint from industrial sources. CO2-EOR refers to a technique for injection of supercritical-dense CO2 into an oil reservoir. Remaining oil, not producible by primary and secondary techniques, has been successfully produced using EOR with CO2 since early 1970??....

  20. Evaluation of soil CO2 production and transport in Duke Forest using a process-based modeling approach

    Science.gov (United States)

    Hui, Dafeng; Luo, Yiqi

    2004-12-01

    Soil surface CO2 efflux is an important component of the carbon cycle in terrestrial ecosystems. However, our understanding of mechanistic controls of soil CO2 production and transport is greatly limited. A multilayer process-based soil CO2 efflux model (PATCIS) was used to evaluate soil CO2 production and transport in the Duke Forest. CO2 production in the soil is the sum of root respiration and soil microbial respiration, and CO2 transport in the soil mainly simulates gaseous diffusion. Simulated soil CO2 efflux in the Duke Forest ranged from 5 g CO2 m-2 d-1 in the winter to 25 g CO2 m-2 d-1 in summer. Annual soil CO2 efflux was 997 and 1211 g C m-2 yr-1 in 1997 and 1998, respectively. These simulations were consistent with the observed soil CO2 efflux. Simulated root respiration contributed 53% to total soil respiration. Soil temperature had the dominant influence on soil CO2 production and CO2 efflux while soil moisture only regulated soil CO2 efflux in the summer when soil moisture was very low. Soil CO2 efflux was sensitive to the specific fine root respiratory rate and live fine root biomass. Elevated CO2 increased annual soil CO2 efflux by 26% in 1997 and 18% in 1998, due mainly to the enhanced live fine root biomass and litterfall. On a daily to yearly basis, CO2 production is almost identical to CO2 efflux, suggesting that CO2 transport is not a critical process regulating daily and long-term soil surface CO2 effluxes in the Duke Forest. We also developed a statistical model of soil CO2 efflux with soil temperature and moisture. Daily soil CO2 efflux estimation by the statistical model showed a similar pattern to the simulated soil CO2 efflux, but the total annual CO2 efflux was slightly lower. While the statistical model is simple, yet powerful, in simulating seasonal dynamics of soil CO2 efflux, the process-based model has the potential to advance our mechanistic understanding of soil CO2 efflux variations in the current and future worlds.

  1. Simulation and Comparative Study of CO2 Capture in Underwater LSS Using HYSYS

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhi-guang; WANG Rong-shun; GU An-zhong

    2007-01-01

    Long-duration manned submersible missions require advanced life support systems (LSS) that can regenerate air, water and food. This study presented two CO2-capture methods used in LSS, CO2 removal with diethanolamine (DEA) and cryo-freezing with liquid oxygen. Both processes were modeled and simulated with HYSYS simulator. The performance of the two types of module was compared, and the results showed that the latter could be advantageous over the former in specific power, facility scale, operation reliability and safety. Economic evaluation suggested the latter cost only half of the former. Cryo-capture module could be an alternative for underwater LSS because of its efficiency and compactness.

  2. Molecular Dynamics Simulations of CO2/Water/Quartz Interfacial Properties: Impact of CO2 Dissolution in Water.

    Science.gov (United States)

    Javanbakht, Gina; Sedghi, Mohammad; Welch, William; Goual, Lamia

    2015-06-01

    The safe trapping of carbon dioxide (CO2) in deep saline aquifers is one of the major concerns of CO2 sequestration. The amount of capillary trapping is dominated by the capillary pressure of water and CO2 inside the reservoir, which in turn is controlled by the interfacial tension (IFT) and the contact angle (CA) of CO2/water/rock systems. The measurement of IFT and CA could be very challenging at reservoir conditions, especially in the presence of toxic cocontaminants. Thus, the ability to accurately predict these interfacial properties at reservoir conditions is very advantageous. Although the majority of existing molecular dynamics (MD) studies of CO2/water/mineral systems were able to capture the trends in IFT and CA variations with pressure and temperature, their predictions often deviated from experimental data, possibly due to erroneous models and/or overlooked chemical reactions. The objective of this study was to improve the MD predictions of IFT and CA of CO2/water/quartz systems at various pressure and temperature conditions by (i) considering the chemical reactions between CO2 and water and (ii) using a new molecular model for α-quartz surface. The results showed that the presence of carbonic acid at the CO2/water interface improved the predictions of IFT, especially at low temperature and high pressure where more CO2 dissolution occurs. On the other hand, the effect on CA was minor. The slight decrease in CA observed across the pressure range investigated could be attributed to an increase in the total number of H-bonds between fluid molecules and quartz surface.

  3. 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.

  4. 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

  5. A New Material Balance Equation Model for Analyzing Dynamic Performance of CO2 Flooding

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Implementing a CO2 flooding scheme successfully requires the capacity to get accurate information of reservoir dynamic performance and fluids injected. Despite some numerical simulation studies, the complicated drive mechanisms and actual reservoir performance have not been fully understood. There is a strong need to develop models from different perspectives to complement current simulators and provide valuable insights into the reservoir performance during CO2 flooding.The aim of this study is to develop a model by using an improved material balance equation (MBE) to analyze quickly the performance of CO2 flooding. After matching the historical field data the proposed model can be used to evaluate,monitor and predict the overall reservoir dynamic performance during CO2 flooding. In order to account accurately for the complex displacement process involving compositional effect and multiphase flow, the PVT properties and flowability of reservoir fluids are incorporated in the model. This study investigates the effects of a number of factors,such as reservoir pressure, the amount of CO2 injected, the CO2 partition ratios in reservoir fluids, the possibility of the existence of a free CO2 gas cap, the proporfon of reservoir fluids contacted with CO2, the starting time of CO2 flooding,oil swelling, and oil flowability improvement by mixing with CO2. The model was used to analyze the CO2 flooding project in Weyburn oil field, Saskatchewan, Canada. This study shows that the proposed model is an effective complementary tool to analyze and monitor the overall reservoir performance during CO2 flooding.

  6. Transient modeling of electrochemically assisted CO2 capture and release

    DEFF Research Database (Denmark)

    Singh, Shobhana; Stechel, Ellen B.; Buttry, Daniel A.

    2017-01-01

    The present work aims to develop a model of a new electrochemical CO2 separation and release technology. We present a one-dimensional transient model of an electrochemical cell for point source CO2 capture and release, which mainly focuses on the simultaneous mass transport and complex chemical...... reactions associated with the separation process. For concreteness, we use an ionic liquid (IL) with 2 M thiolate anion (RS−) in 1 M disulfide (RSSR) as an electrolyte in the electrochemical cell to capture, transport and release CO2 under standard operating conditions. We computationally solved the model...... to analyze the time-dependent behavior of CO2 capture and electro-migration transport across the cell length. Given high nonlinearity of the system, we used a finite element method (FEM) to numerically solve the coupled mass transport equations. The model describes the concentration profiles by taking...

  7. Numerical modeling of cold magmatic CO2 flux measurements for the exploration of hidden geothermal systems

    Science.gov (United States)

    Peiffer, Loïc.; Wanner, Christoph; Pan, Lehua

    2015-10-01

    The most accepted conceptual model to explain surface degassing of cold magmatic CO2 in volcanic-geothermal systems involves the presence of a gas reservoir. In this study, numerical simulations using the TOUGH2-ECO2N V2.0 package are performed to get quantitative insights into how cold CO2 soil flux measurements are related to reservoir and fluid properties. Although the modeling is based on flux data measured at a specific geothermal site, the Acoculco caldera (Mexico), some general insights have been gained. Both the CO2 fluxes at the surface and the depth at which CO2 exsolves are highly sensitive to the dissolved CO2 content of the deep fluid. If CO2 mainly exsolves above the reservoir within a fracture zone, the surface CO2 fluxes are not sensitive to the reservoir size but depend on the CO2 dissolved content and the rock permeability. For gas exsolution below the top of the reservoir, surface CO2 fluxes also depend on the gas saturation of the deep fluid as well as the reservoir size. The absence of thermal anomalies at the surface is mainly a consequence of the low enthalpy of CO2. The heat carried by CO2 is efficiently cooled down by heat conduction and to a certain extent by isoenthalpic volume expansion depending on the temperature gradient. Thermal anomalies occur at higher CO2 fluxes (>37,000 g m-2 d-1) when the heat flux of the rising CO2 is not balanced anymore. Finally, specific results are obtained for the Acoculco area (reservoir depth, CO2 dissolved content, and gas saturation state).

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  9. 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.

  10. Pore-scaling Modeling of Physical Property Changes During CO2 Injection into Sandstone

    Science.gov (United States)

    Keehm, Y.; Yoo, G.

    2009-12-01

    Carbon dioxide is a green-house gas and is believed to be an important factor in global warming and climate change. Many countries around the world are working on reducing and sequestrating CO2 to follow international regulations. One of promising area for CO2 sequestration is the storage in geological formation. To accurately determine the performance of geological injection and storage, quantification and monitoring of the physical property changes are essential. In this paper, we are presenting a new approach for the monitoring of CO2 sequestration in sandstone using pore-scale simulation techniques. The method consists of three steps: 1) acquisition of high-resolution pore microstructures by X-ray micro-tomography; 2) CO2 injection simulation using lattice-Boltzmann (LB) two-phase flow simulation; and 3) FEM property simulations (electrical and elastic) at different CO2 saturations during the injection. We use three different sandstone samples: sand-pack, Berea sandstone, and B2 sandstone from offshore of Korea. The porosity of the sand-pack is 42% and that of two sandstone samples is around 17%. The digital pore structures were obtained by X-ray micro-tomography with a spatial resolution of 2 micron. The LB two-phase flow simulation is then conducted by injecting CO2 into fully water-saturated samples and gives a realistic movement of CO2 in the pore structure. At each CO2 saturation, electrical and elastic properties are determined by pore-scale FEM simulation techniques. The electrical conductivity decreases almost linearly as CO2 saturations increases; however, the P-wave velocity decrease more rapidly at the low CO2 saturation (up to 30%), than at higher saturation. S-wave velocity does not show any significant changes. The higher porosity rock shows more sensitivity to saturation changes. The modeling shows that we can have quantitative relations between physical properties and CO2 saturation, which can be used to determine injection performance and

  11. Simulation of climate change impacts on grain sorghum production grown under free air CO2 enrichment

    Science.gov (United States)

    Fu, Tongcheng; Ko, Jonghan; Wall, Gerard W.; Pinter, Paul J.; Kimball, Bruce A.; Ottman, Michael J.; Kim, Han-Yong

    2016-07-01

    Potential impacts of climate change on grain sorghum (Sorghum bicolor) productivity were investigated using the CERES-sorghum model in the Decision Support System for Agrotechnology Transfer v4.5. The model was first calibrated for a sorghum cultivar grown in a free air CO2 enrichment experiment at the University of Arizona, Maricopa, Arizona, USA in 1998. The model was then validated with an independent dataset collected in 1999. The simulated grain yield, growth, and soil water of sorghum for the both years were in statistical agreement with the corresponding measurements, respectively. Neither simulated nor measured yields responded to elevated CO2, but both were sensitive to water supply. The validated model was then applied to simulate possible effects of climate change on sorghum grain yield and water use efficiency in western North America for the years 2080-2100. The projected CO2 fertilizer effect on grain yield was dominated by the adverse effect of projected temperature increases. Therefore, temperature appears to be a dominant driver of the global climate change influencing future sorghum productivity. These results suggest that an increase in water demand for sorghum production should be anticipated in a future high-CO2 world.

  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. 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.

  14. A statistical analysis of three ensembles of crop model responses totemperature and CO2concentration

    DEFF Research Database (Denmark)

    Makowski, D; Asseng, S; Ewert, F.

    2015-01-01

    levels, and can thus be used to calculate temperature and [CO2] thresholds leading to yield loss or yield gain, without re-running the original complex crop models. Our approach is illustrated with three yield datasets simulated by 19 maize models, 26 wheat models, and 13 rice models. Several statistical......Ensembles of process-based crop models are increasingly used to simulate crop growth for scenarios of temperature and/or precipitation changes corresponding to different projections of atmospheric CO2 concentrations. This approach generates large datasets with thousands of simulated crop yield data...... in the simulation protocols. Here we demonstrate that statistical models based on random-coefficient regressions are able to emulate ensembles of process-based crop models. An important advantage of the proposed statistical models is that they can interpolate between temperature levels and between CO2 concentration...

  15. 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 CO2 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 CO2 loading capacity and high CO2/N2 selectivity. It has been reported that ultramicroporous character and surface nitrogen functionality are of great importance to the enhancement of CO2 capacity and CO2/N2 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 CO2 loading (4.31 mmol g(-1)) and CO2/N2 selectivity (138.3 : 1). Increasing surface nitrogen content resulted in enhanced loading and excellent CO2/N2 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.

  16. Discrete element modeling of indentation tests to investigate mechanisms of CO2-related chemomechanical rock alteration

    Science.gov (United States)

    Sun, Zhuang; Espinoza, D. Nicolas; Balhoff, Matthew T.

    2016-11-01

    During CO2 injection into geological formations, petrophysical and geomechanical properties of host formations can be altered due to mineral dissolution and precipitation. Field and laboratory results have shown that sandstone and siltstone can be altered by CO2-water mixtures, but few quantitative studies have been performed to fully investigate underlying mechanisms. Based on the hypothesis that CO2-water mixtures alter the integrity of rock structure by attacking cements rather than grains, we attempt to explain the degradation of cementation due to long-term contact with CO2 and water and mechanisms for changes in rock mechanical properties. Many sandstones, including calcite-cemented quartzitic sandstone, chlorite-cemented quartzitic sandstone, and hematite-cemented quartzitic sandstone, contain interparticle cements that are more readily affected by CO2-water mixtures than grains. A model that couples the discrete element method and the bonded-particle model is used to perform simulations of indentation tests on synthetic rocks with crystal and random packings. The model is verified against the analytical cavity expansion model and validated against laboratory indentation tests on Entrada sandstone with and without CO2 alteration. Sensitivity analysis is performed for cementation microscopic parameters including stiffness, size, axial, and shear strength. The simulation results indicate that the CO2-related degradation of mechanical properties in bleached Entrada sandstone can be attributed to the reduction of cement size rather than cement strength. Our study indicates that it is possible to describe the CO2-related rock alteration through particle-scale mechanisms.

  17. Kinetics of CH4 and CO2 hydrate dissociation and gas bubble evolution via MD simulation.

    Science.gov (United States)

    Uddin, M; Coombe, D

    2014-03-20

    Molecular dynamics simulations of gas hydrate dissociation comparing the behavior of CH4 and CO2 hydrates are presented. These simulations were based on a structurally correct theoretical gas hydrate crystal, coexisting with water. The MD system was first initialized and stabilized via a thorough energy minimization, constant volume-temperature ensemble and constant volume-energy ensemble simulations before proceeding to constant pressure-temperature simulations for targeted dissociation pressure and temperature responses. Gas bubble evolution mechanisms are demonstrated as well as key investigative properties such as system volume, density, energy, mean square displacements of the guest molecules, radial distribution functions, H2O order parameter, and statistics of hydrogen bonds. These simulations have established the essential similarities between CH4 and CO2 hydrate dissociation. The limiting behaviors at lower temperature (no dissociation) and higher temperature (complete melting and formation of a gas bubble) have been illustrated for both hydrates. Due to the shift in the known hydrate stability curves between guest molecules caused by the choice of water model as noted by other authors, the intermediate behavior (e.g., 260 K) showed distinct differences however. Also, because of the more hydrogen-bonding capability of CO2 in water, as reflected in its molecular parameters, higher solubility of dissociated CO2 in water was observed with a consequence of a smaller size of gas bubble formation. Additionally, a novel method for analyzing hydrate dissociation based on H-bond breakage has been proposed and used to quantify the dissociation behaviors of both CH4 and CO2 hydrates. Activation energies Ea values from our MD studies were obtained and evaluated against several other published laboratory and MD values. Intrinsic rate constants were estimated and upscaled. A kinetic reaction model consistent with macroscale fitted kinetic models has been proposed to

  18. Phase Equilibria of Water/CO2 and Water/n-Alkane Mixtures from Polarizable Models.

    Science.gov (United States)

    Jiang, Hao; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2017-02-16

    Phase equilibria of water/CO2 and water/n-alkane mixtures over a range of temperatures and pressures were obtained from Monte Carlo simulations in the Gibbs ensemble. Three sets of Drude-type polarizable models for water, namely the BK3, GCP, and HBP models, were combined with a polarizable Gaussian charge CO2 (PGC) model to represent the water/CO2 mixture. The HBP water model describes hydrogen bonds between water and CO2 explicitly. All models underestimate CO2 solubility in water if standard combining rules are used for the dispersion interactions between water and CO2. With the dispersion parameters optimized to phase compositions, the BK3 and GCP models were able to represent the CO2 solubility in water, however, the water composition in CO2-rich phase is systematically underestimated. Accurate representation of compositions for both water- and CO2-rich phases cannot be achieved even after optimizing the cross interaction parameters. By contrast, accurate compositions for both water- and CO2-rich phases were obtained with hydrogen bonding parameters determined from the second virial coefficient for water/CO2. Phase equilibria of water/n-alkane mixtures were also studied using the HBP water and an exponenial-6 united-atom n-alkanes model. The dispersion interactions between water and n-alkanes were optimized to Henry's constants of methane and ethane in water. The HBP water and united-atom n-alkane models underestimate water content in the n-alkane-rich phase; this underestimation is likely due to the neglect of electrostatic and induction energies in the united-atom model.

  19. Spectral-element simulations of carbon dioxide (CO2) sequestration time-lapse monitoring

    Science.gov (United States)

    Morency, C.; Luo, Y.; Tromp, J.

    2009-12-01

    Geologic sequestration of CO2, a green house gas, represents an effort to reduce the large amount of CO2 generated as a by-product of fossil fuels combustion and emitted into the atmosphere. This process of sequestration involves CO2 storage deep underground. There are three main storage options: injection into hydrocarbon reservoirs, injection into methane-bearing coal beds, or injection into deep saline aquifers, that is, highly permeable porous media. The key issues involve accurate monitoring of the CO2, from the injection stage to the prediction & verification of CO2 movement over time for environmental considerations. A natural non-intrusive monitoring technique is referred to as ``4D seismics'', which involves 3D time-lapse seismic surveys. The success of monitoring the CO2 movement is subject to a proper description of the physics of the problem. We propose to realize time-lapse migrations comparing acoustic, elastic, and poroelastic simulations of 4D seismic imaging to characterize the storage zone. This approach highlights the influence of using different physical theories on interpreting seismic data, and, more importantly, on extracting the CO2 signature from the seismic wave field. Our simulations are performed using a spectral-element method, which allows for highly accurate results. Biot's equations are implemented to account for poroelastic effects. Attenuation associated with the anelasticity of the rock frame and frequency-dependent viscous resistance of the pore fluid are accommodated based upon a memory variable approach. The sensitivity of observables to the model parameters is quantified based upon finite-frequency sensitivity kernels calculated using an adjoint method.

  20. Laboratory simulation system, using Carcinus maenas as the model organism, for assessing the impact of CO2 leakage from sub-seabed injection and storage.

    Science.gov (United States)

    Rodríguez-Romero, Araceli; Jiménez-Tenorio, Natalia; Riba, Inmaculada; Blasco, Julián

    2016-01-01

    The capture and storage of CO2 in sub-seabed geological formations has been proposed as one of the potential options to decrease atmospheric CO2 concentrations in order to mitigate the abrupt and irreversible consequences of climate change. However, it is possible that CO2 leakages could occur during the injection and sequestration procedure, with significant repercussions for the marine environment. We investigate the effects of acidification derived from possible CO2 leakage events on the European green crab, Carcinus maenas. To this end, a lab-scale experiment involving direct release of CO2 was conducted at pH values between 7.7 and 6.15. Female crabs were exposed for 10 days to sediment collected from two different coastal areas, one with relatively uncontaminated sediment (RSP) and the other with known contaminated sediment (MZ and ML), under the pre-established seawater pH conditions. Survival rate, histopathological damage and metal (Fe, Mn, Cu, Zn, Cr, Cd and Pb) and As accumulation in gills and hepatopancreas tissue were employed as endpoints. In addition, the obtained results were compared with the results of the physico-chemical characterization of the sediments, which included the determination of the metals Fe, Mn, Cu, Zn, Cr, Pb and Cd, the metalloid As, certain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), as well as nonchemical sediment properties (grain size, organic carbon and total organic matter). Significant associations were observed between pH and the histological damage. Concentrations of Fe, Mn, Cr, Pb, Cd and PAHs in sediment, presented significant negative correlations with the damage to gills and hepatopancreas, and positive correlations with metal accumulation in both tissues. The results obtained in this study reveal the importance of sediment properties in the biological effects caused by possible CO2 leakage. However, a clear pattern was not observed between metal accumulation in tissues and p

  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.; Boote, Kenneth J.; Thorburn, Peter J.; Kersebaum, Kurt Christian; Aggarwal, Pramod K.; Angulo, Carlos; Basso, Bruno; Bertuzzi, Patrick; Biernath, Christian; Brisson, Nadine; Challinor, Andrew J.; Doltra, Jordi; Gayler, Sebastian; Goldberg, Richie; Heng, Lee; Steduto, Pasquale

    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. 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...... absorber. The influence of the application of different mass transfer correlations on the model's performance is investigated. Analytical expressions for the calculation of the enhancement factor for the second order as well as the pseudo-first-order reaction regime are integrated in the model......, 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....

  3. 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

  4. 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.

  5. Development of density plumes of dissolved CO2: Comparing experimental observations with numerical simulations

    Science.gov (United States)

    Kirk, Karen; Vosper, Hayley; Rochelle, Chris; Noy, Dave; Chadwick, Andy

    2014-05-01

    permeability of the system was calculated to be 2.2-2.5 x 10-9 m2, and this used for modelling work. Having experimentally reproduced the transition from diffusion-dissolution to convection-dissolution, and from this determined the system properties, we simulated the process in a numerical flow model. A high resolution model of the Hele-Shaw cell was built using the TOUGH2 flow simulator with the ECO 2N fluid property module, with a permeability of 2.5 x 10-9 m2, and applying laboratory pressure and temperature conditions. Plume development in terms of onset time, sinking rate and wavelength statistics are closely comparable between experiment and model. This suggests therefore that the numerical flow simulator was able to reproduce the critical process of transition from diffusion-dominated to convection-dominated processes in a realistic way. This further increases our confidence in the suitability of numerical models in making predictions of system evolution within CO2 storage schemes.

  6. CO2 capture using aqueous ammonia: kinetic study and process simulation

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J.M.; Stenby, Erling Halfdan

    2011-01-01

    Carbon dioxide capture using aqueous ammonia is a post-combustion technology that has shown a good potential. Therefore this process is studied by measuring the rate of absorption of carbon dioxide by aqueous ammonia and by performing process simulation. The rate of absorption of carbon dioxide...... to 0.6. The results were compared with those found for 30 wt% mono-ethanolamine (MEA) solutions.The capture process was simulated successfully using the simulator Aspen Plus coupled with the extended UNIQUAC thermodynamic model available for the NH3–CO2–H2O system. For this purpose, a user model...

  7. 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.

  8. High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals

    Directory of Open Access Journals (Sweden)

    T. Koch

    2010-01-01

    Full Text Available Satellite retrievals for column CO2 with better spatial and temporal sampling are expected to improve the current surface flux estimates of CO2 via inverse techniques. However, the spatial scale mismatch between remotely sensed CO2 and current generation inverse models can induce representation errors, which can cause systematic biases in flux estimates. This study is focused on estimating these representation errors associated with utilization of satellite measurements in global models with a horizontal resolution of about 1 degree or less. For this we used simulated CO2 from the high resolution modeling framework WRF-VPRM, which links CO2 fluxes from a diagnostic biosphere model to a weather forecasting model at 10×10 km2 horizontal resolution. Sub-grid variability of column averaged CO2, i.e. the variability not resolved by global models, reached up to 1.2 ppm with a median value of 0.4 ppm. Statistical analysis of the simulation results indicate that orography plays an important role. Using sub-grid variability of orography and CO2 fluxes as well as resolved mixing ratio of CO2, a linear model can be formulated that could explain about 50% of the spatial patterns in the systematic (bias or correlated error component of representation error in column and near-surface CO2 during day- and night-times. These findings give hints for a parameterization of representation error which would allow for the representation error to taken into account in inverse models or data assimilation systems.

  9. Multi-scale modeling of CO2 dispersion leaked from seafloor off the Japanese coast.

    Science.gov (United States)

    Kano, Yuki; Sato, Toru; Kita, Jun; Hirabayashi, Shinichiro; Tabeta, Shigeru

    2010-02-01

    A numerical simulation was conducted to predict the change of pCO(2) in the ocean caused by CO(2) leaked from an underground aquifer, in which CO(2) is purposefully stored. The target space of the present model was the ocean above the seafloor. The behavior of CO(2) bubbles, their dissolution, and the advection-diffusion of dissolved CO(2) were numerically simulated. Here, two cases for the leakage rate were studied: an extreme case, 94,600 t/y, which assumed that a large fault accidentally connects the CO(2) reservoir and the seafloor; and a reasonable case, 3800 t/y, based on the seepage rate of an existing EOR site. In the extreme case, the calculated increase in DeltapCO(2) experienced by floating organisms was less than 300 ppm, while that for immobile organisms directly over the fault surface periodically exceeded 1000 ppm, if momentarily. In the reasonable case, the calculated DeltapCO(2) and pH were within the range of natural fluctuation. Copyright 2009 Elsevier Ltd. All rights reserved.

  10. 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.

  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. Intra-aggregate CO2 enrichment: a modelling approach for aerobic soils

    Directory of Open Access Journals (Sweden)

    H. Schack-Kirchner

    2012-10-01

    Full Text Available CO2 concentration gradients inside soil aggregates, caused by the respiration of soil microorganisms and fungal hyphae, might lead to variations in the soil solution chemistry on a mm-scale, and to an underestimation of the CO2 storage. But, up to now, there seems to be no feasible method for measuring CO2 inside natural aggregates with sufficient spatial resolution. We combined a one-dimensional model for gas diffusion in the inter-aggregate pore-space with a cylinder diffusion model, simulating the consumption/production and diffusion of O2 and CO2 inside soil aggregates with air- and water-filled pores. Our model predicts that for aerobic respiration (respiratory quotient = 1 the intra-aggregate increase in the CO2 partial pressure can never be higher than 0.9 kPa for siliceous, and 0.08 kPa for calcaric aggregates, independent of the level of water-saturation. This suggests that only for siliceous aggregates CO2 produced by aerobic respiration might cause a high small-scale spatial variability in the soil solution chemistry. In calcaric aggregates, however, the contribution of carbonate species to the CO2 transport should lead to secondary carbonates on the aggregate surfaces. As regards the total CO2 storage in aerobic soils, both siliceous and calcaric, the effect of intra-aggregate CO2 gradients seems to be negligible. To assess the effect of anaerobic respiration on the intra-aggregate CO2 gradients, the development of a device for measuring CO2 on a mm-scale in soils is indispensable.

  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 o

  14. 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

  15. Modeling pCO2 variability in the Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Z. Xue

    2014-08-01

    Full Text Available A three-dimensional coupled physical–biogeochemical model was used to simulate and examine temporal and spatial variability of surface pCO2 in the Gulf of Mexico (GoM. The model is driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A seven-year model hindcast (2004–2010 was performed and was validated against in situ measurements. The model revealed clear seasonality in surface pCO2. Based on the multi-year mean of the model results, the GoM is an overall CO2 sink with a flux of 1.34 × 1012 mol C yr−1, which, together with the enormous fluvial carbon input, is balanced by the carbon export through the Loop Current. A sensitivity experiment was performed where all biological sources and sinks of carbon were disabled. In this simulation surface pCO2 was elevated by ~ 70 ppm, providing the evidence that biological uptake is a primary driver for the observed CO2 sink. The model also provided insights about factors influencing the spatial distribution of surface pCO2 and sources of uncertainty in the carbon budget.

  16. Uptake and Storage of Anthropogenic CO2 in the Pacific Ocean Estimated Using Two Modeling Approaches

    Institute of Scientific and Technical Information of China (English)

    LI Yangchun; XU Yongfu

    2012-01-01

    A basin-wide ocean general circulation model (OGCM) of the Pacific Ocean is employed to estimate the uptake and storage of anthropogenic CO2 using two different simulation approaches.The simulation (named BIO) makes use of a carbon model with biological processes and full thermodynamic equations to calculate surface water partial pressure of CO2,whereas the other simulation (named PTB) makes use of a perturbation approach to calculate surface water partial pressure of anthropogenie CO2.The results from the two simulations agree well with the estimates based on observation data in most important aspects of the vertical distribution as well as the total inventory of anthropogenic carbon.The storage of anthropogenic carbon from BIO is closer to the observation-based estimate than that from PTB.The Revelle factor in 1994 obtained in BIO is generally larger than that obtained in PTB in the whole Pacific,except for the subtropical South Pacific.This,to large extent,leads to the difference in the surface anthropogenic CO2 concentration between the two runs.The relative difference in the annual uptake between the two runs is almost constant during the integration processes after 1850.This is probably not caused by dissolved inorganic carbon (DIC),but rather by a factor independent of time.In both runs,the rate of change in anthropogenic CO2 fluxes with time is consistent with the rate of change in the growth rate of atmospheric partial pressure of CO2.

  17. CO2 migration in the vadose zone: experimental and numerical modelling of controlled gas injection

    Science.gov (United States)

    gasparini, andrea; credoz, anthony; grandia, fidel; garcia, david angel; bruno, jordi

    2014-05-01

    The mobility of CO2 in the vadose zone and its subsequent transfer to the atmosphere is a matter of concern in the risk assessment of the geological storage of CO2. In this study the experimental and modelling results of controlled CO2 injection are reported to better understanding of the physical processes affecting CO2 and transport in the vadose zone. CO2 was injected through 16 micro-injectors during 49 days of experiments in a 35 m3 experimental unit filled with sandy material, in the PISCO2 facilities at the ES.CO2 centre in Ponferrada (North Spain). Surface CO2 flux were monitored and mapped periodically to assess the evolution of CO2 migration through the soil and to the atmosphere. Numerical simulations were run to reproduce the experimental results, using TOUGH2 code with EOS7CA research module considering two phases (gas and liquid) and three components (H2O, CO2, air). Five numerical models were developed following step by step the injection procedure done at PISCO2. The reference case (Model A) simulates the injection into a homogeneous soil(homogeneous distribution of permeability and porosity in the near-surface area, 0.8 to 0.3 m deep from the atmosphere). In another model (Model B), four additional soil layers with four specific permeabilities and porosities were included to predict the effect of differential compaction on soil. To account for the effect of higher soil temperature, an isothermal simulation called Model C was also performed. Finally, the assessment of the rainfall effects (soil water saturation) on CO2 emission on surface was performed in models called Model D and E. The combined experimental and modelling approach shows that CO2 leakage in the vadose zone quickly comes out through preferential migration pathways and spots with the ranges of fluxes in the ground/surface interface from 2.5 to 600 g·m-2·day-1. This gas channelling is mainly related to soil compaction and climatic perturbation. This has significant implications to

  18. Molecular dynamics simulations for the growth of CH4-CO2 mixed hydrate

    Institute of Scientific and Technical Information of China (English)

    Lizhi Yi; Deqing Liang; Xuebing Zhou; Dongliang Li

    2014-01-01

    Molecular dynamics simulations are performed to study the growth mechanism of CH4-CO2 mixed hydrate in xCO2=75%, xCO2=50%, and xCO2=25%systems at T =250 K, 255 K and 260 K, respectively. Our simulation results show that the growth rate of CH4-CO2 mixed hydrate increases as the CO2 concentration in the initial solution phase increases and the temperature decreases. Via hydrate formation, the composition of CO2 in hydrate phase is higher than that in initial solution phase and the encaging capacity of CO2 in hydrates increases with the decrease in temperature. By analysis of the cage occupancy ratio of CH4 molecules and CO2 molecules in large cages to small cages, we find that CO2 molecules are preferably encaged into the large cages of the hydrate crystal as compared with CH4 molecules. Interestingly, CH4 molecules and CO2 molecules frequently replace with each other in some particular cage sites adjacent to hydrate/solution interface during the crystal growth process. These two species of guest molecules eventually act to stabilize the newly formed hydrates, with CO2 molecules occupying large cages and CH4 molecules occupying small cages in hydrate.

  19. CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements

    Science.gov (United States)

    Li, Rong; Zhang, Meigen; Chen, Liangfu; Kou, Xingxia; Skorokhod, Andrei

    2017-07-01

    Satellite observations are widely used in global CO2 assimilations, but their quality for use in regional assimilation systems has not yet been thoroughly determined. Validation of satellite observations and model simulations of CO2 is crucial for carbon flux inversions. In this study, we focus on evaluating the uncertainties of model simulations and satellite observations. The atmospheric CO2 distribution in East Asia during 2012 was simulated using a regional chemical transport model (RAMS-CMAQ) and compared with both CO2 column density (XCO2) from the Gases Observing SATellite (GOSAT) and CO2 concentrations from the World Data Centre for Greenhouse Gases (WDCGG). The results indicate that simulated XCO2 is generally lower than GOSAT XCO2 by 1.19 ppm on average, and their monthly differences vary from 0.05 to 2.84 ppm, with the corresponding correlation coefficients ranging between 0.1 and 0.67. CMAQ simulations are good to capture the CO2 variation as ground-based observations, and their correlation coefficients are from 0.62 to 0.93, but the average value of CMAQ simulation is 2.4 ppm higher than ground-based observation. Thus, we inferred that the GOSAT retrievals may overestimate XCO2, which is consistent with the validation of GOSAT XCO2 using Total Carbon Column Observing Network measurements. The near-surface CO2 concentration was obviously overestimated in GOSAT XCO2. Compared with the relatively small difference between CMAQ and GOSAT XCO2, the large difference in CO2 near surface or their vertical profiles indicates more improvements are needed to reduce the uncertainties in both satellite observations and model simulations.

  20. The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble

    Directory of Open Access Journals (Sweden)

    P. R. Halloran

    2014-10-01

    vary rapidly. Given the importance of this sink and its apparent variability, it is critical that we understand the mechanisms behind its operation. Here we explore subpolar North Atlantic CO2 uptake across a large ensemble of Earth System Model simulations, and find that models show a peak in sink strength around the middle of the century after which CO2 uptake begins to decline. We identify different drivers of change on interannual and multidecadal timescales. Short-term variability appears to be driven by fluctuations in regional seawater temperature and alkalinity, whereas the longer-term evolution throughout the coming century is largely occurring through a counterintuitive response to rising atmospheric CO2 concentrations. At high atmospheric CO2 concentrations the contrasting Ravelle factors between the subtropical and subpolar gyres, combined with the transport of surface waters from the subtropical to subpolar gyre, means that the subpolar CO2 uptake capacity is largely satisfied from its southern boundary rather than through air–sea CO2 flux. Our findings indicate that: (i we can explain the mechanisms of subpolar North Atlantic CO2 uptake variability across a broad range of Earth System Models, (ii a focus on understanding the mechanisms behind contemporary variability may not directly tell us about how the sink will change in the future, (iii to identify long-term change in the North Atlantic CO2 sink we should focus observational resources on monitoring subtropical as well as the subpolar seawater CO2, (iv recent observations of a weakening subpolar North Atlantic CO2 sink suggests that the sink strength is already in long-term decline.

  1. Mathematical modeling as a tool to assess microbial community responses to CO2 injection

    Science.gov (United States)

    Vilcaez, J.

    2014-12-01

    The issue of subsurface microbial community responses to the injection of CO2 has great importance not only from a risk assessment point of view but also from the perspective of CO2 recycling to CH4. In this sense, the objective of this study is to develop mathematical models to make a quantitative description of the responses of subsurface indigenous microbial communities to the injection of CO2. For this end, TOUGHREACTV1.2 reactive transport simulator with its module ECO2N is used as the modeling framework. The targeted microbial community is composed of fermentative bacteria (Organic matter → Acetate & H2), acetotrophic methanogens (Acetate → Methane & CO2), acetotrophic Sulfate Reducing Bacteria (SRB) (Acetate → H2S & CO2), hydrogenotrophic methanogens (H2 & CO2 → CH4), and hydrogenotrophic SRB (H2 → H2S). Due to the multiple hydrogeological, geochemical and microbiological factors intervening in both the response of subsurface microbial communities to the injection of CO2 and the chemical and physical fate of CO2 itself, at this stage simulations have been performed in batch mode. That means numerical simulations aimed to track changes in CO2 saturation levels, pH, and concentrations of mineral and aqueous phase species over time at selected initial conditions. Numerical simulation results indicate that the activity of microbes associated with methanogenic processes in geological storage sites of CO2 is governed by the level of CO2 saturation in the pore space as well as by the presence of pH buffering minerals such as calcite. With calcite in the mineral phase attenuating drops in pH below inhibitory levels, for instance it is shown that acetotrophic and hydrogenotrophic SRB outcompete acetotrophic and hydrogenotrophic methanogens for acetate and H2, respectively. During the initial stages of the reaction when the pH level is lowest, the higher tolerance of hydrogenotrophic methanogens to acidic pH levels is reflected by a preferential formation of

  2. 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.

  3. 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.

  4. Conditional Methods in Modeling CO2 Capture from Coal Syngas

    Directory of Open Access Journals (Sweden)

    Dmitry N. Saulov

    2014-03-01

    Full Text Available Gasification of coal or biomass with in-situ CO2 capture is an emerging technology aiming to address the problem of climate change. Development of a CO2 sorbent with desirable properties and understanding the behavior of such a material in carbonation/calcination reactions is an important part of developing the technology. In this paper, we report experimental results describing the carbonation behavior of three synthetic CaO-based sorbents. We also present a physically-based model of the reactive transport processes in sorbent particles, which have complicated pore structures. This modeling is based on the conditional approach (i.e., conditional moment closure (CMC, which has proven to be successful in modeling reactive transport phenomena in porous media. The model predictions are in good agreement with the experimental data.

  5. 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

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

    Science.gov (United States)

    Wang, James S.; Kawa, S. Randolph; Eluszkiewicz, Janusz; Collatz, G. J.; Mountain, Marikate; Henderson, John; Nehrkorn, Thomas; Aschbrenner, Ryan; Zaccheo, T. Scott

    2012-01-01

    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.

  7. Biases in atmospheric CO2 estimates from correlated meteorology modeling errors

    Science.gov (United States)

    Miller, S. M.; Hayek, M. N.; Andrews, A. E.; Fung, I.; Liu, J.

    2015-03-01

    Estimates of CO2 fluxes that are based on atmospheric measurements rely upon a meteorology model to simulate atmospheric transport. These models provide a quantitative link between the surface fluxes and CO2 measurements taken downwind. Errors in the meteorology can therefore cause errors in the estimated CO2 fluxes. Meteorology errors that correlate or covary across time and/or space are particularly worrisome; they can cause biases in modeled atmospheric CO2 that are easily confused with the CO2 signal from surface fluxes, and they are difficult to characterize. In this paper, we leverage an ensemble of global meteorology model outputs combined with a data assimilation system to estimate these biases in modeled atmospheric CO2. In one case study, we estimate the magnitude of month-long CO2 biases relative to CO2 boundary layer enhancements and quantify how that answer changes if we either include or remove error correlations or covariances. In a second case study, we investigate which meteorological conditions are associated with these CO2 biases. In the first case study, we estimate uncertainties of 0.5-7 ppm in monthly-averaged CO2 concentrations, depending upon location (95% confidence interval). These uncertainties correspond to 13-150% of the mean afternoon CO2 boundary layer enhancement at individual observation sites. When we remove error covariances, however, this range drops to 2-22%. Top-down studies that ignore these covariances could therefore underestimate the uncertainties and/or propagate transport errors into the flux estimate. In the second case study, we find that these month-long errors in atmospheric transport are anti-correlated with temperature and planetary boundary layer (PBL) height over terrestrial regions. In marine environments, by contrast, these errors are more strongly associated with weak zonal winds. Many errors, however, are not correlated with a single meteorological parameter, suggesting that a single meteorological proxy is

  8. 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.

  9. Spatiotemporal variability and drivers of pCO2 and air–sea CO2 fluxes in the California Current System: an eddy-resolving modeling study

    Directory of Open Access Journals (Sweden)

    G. Turi

    2013-08-01

    Full Text Available We quantify the CO2 source/sink nature of the California Current System (CalCS and determine the drivers and processes behind the mean and spatiotemporal variability of the partial pressure of CO2 (pCO2 in the surface ocean. To this end, we analyze eddy-resolving, climatological simulations of a coupled physical-ecosystem-biogeochemical ocean model on the basis of the Regional Oceanic Modeling System (ROMS. The model-simulated pCO2 agrees very well with in situ observations over the entire domain with virtually no bias, but the model overestimates pCO2 in the nearshore 100 km, and underestimates the observed temporal variability. In the annual mean, the entire CalCS within 800 km of the coast and from ~ 33° N to 46° N is essentially neutral with regard to atmospheric CO2. The model simulates an integrated uptake flux of −0.9 Tg C yr–1, corresponding to a very small average flux density of −0.05 mol C m–2 yr–1, with an uncertainty of the order of ±0.20 mol C m–2 yr–1. This near zero flux is a consequence of an almost complete regional compensation between the strong outgassing in the nearshore region (first 100 km, with flux densities of more than 3 mol C m–2 yr–1 and a weaker, but more widespread uptake flux in the offshore region with an average flux density of −0.17 mol C m–2 yr–1. This pattern is primarily a result of the interaction between upwelling in the nearshore that brings waters with high concentrations of dissolved inorganic carbon (DIC to the surface, and an intense biological drawdown of this DIC, driven by the nutrients that are upwelled together with the DIC. The biological drawdown occurs too slowly to prevent the escape of a substantial amount of CO2 into the atmosphere, but this is compensated by the biological generation of undersaturated conditions offshore of 100 km, permitting the CalCS to take up most of the escaped CO2. Thus, the biological pump over the entire CalCS is essentially 100

  10. Carbon deposition in CH4/CO2 operated SOFC: Simulation and experimentation studies

    Science.gov (United States)

    Girona, K.; Laurencin, J.; Fouletier, J.; Lefebvre-Joud, F.

    2012-07-01

    Due to their high operating temperatures, SOFCs can be directly fed with biogas, mainly composed of CH4 and CO2. In this work, experiments was performed with a classical Ni-YSZ cermet//YSZ//LSM cell fed either with a synthetic simulated biogas (CH4/CO2 ratio equal to 1 with 6% humidity), or with humidified H2. In both cases, the performances are found to be very similar, which confirms the ability of SOFCs to operate with internal reforming of biogas. Nevertheless, carbon formation in these operating conditions needs to be considered because of durability concerns. Thermodynamic calculations and modelling are carried out to evaluate the risk of carbon deposition depending on operating parameters. In the ternary diagram Csbnd Hsbnd O, the limits for carbon deposition are plotted, allowing the determination of “safe” operating conditions in terms of CH4 inlet flow rate and cell voltage. First experiments confirm these modelling results.

  11. 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.

  12. Atomistic simulation of CO2 solubility in poly(ethylene oxide) oligomers

    Science.gov (United States)

    Hong, Bingbing; Panagiotopoulos, Athanassios Z.

    2014-06-01

    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(CH2CH2O)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 Henry's constant of CO2 in PEO have also been investigated. Addition of modest amounts of water in PEO produces a relatively small increase in Henry's constant. Dependence of the calculated Henry's constant on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length.

  13. Theoretical simulation of CO2 capture in organic cage impregnated with polyoxometalates.

    Science.gov (United States)

    Gao, Jingyuan; Li, Wenliang; Zhang, Jingping

    2017-04-05

    To explore the adsorption and separation properties of CO2 in a novel material consisting of a series of polyoxometalates (POMs) impregnated within supramolecular porous catenane (shorted as SPC), grand canonical Monte Carlo (GCMC) simulations and ab initio calculations were used. GCMC simulations showed this impregnation can enhance CO2 /CH4 (or CO2 /N2 ) selectivity almost 30 times compared to the bare SPC due to the strong interaction of CO2 with the nPOMs@SPC structures. And, the loading of CO2 inhibits the adsorption of CH4 (or N2 ) as CO2 occupying the preferred adsorption sites. Furthermore, the effect of number, mass, and volume of POMs inserted in SPC on CO2 /CH4 (or CO2 /N2 ) selectivity over large pressure range was investigated in detail. Additionally, the accurate ab initio calculations further confirmed our GCMC simulations. As a result, the proposed nPOMs@SPC structures are promising candidates for CO2 /N2 and CO2 /CH4 separations. © 2017 Wiley Periodicals, Inc.

  14. Modeling pCO2 variability in the Gulf of Mexico

    Science.gov (United States)

    Xue, Zuo; He, Ruoying; Fennel, Katja; Cai, Wei-Jun; Lohrenz, Steven; Huang, Wei-Jen; Tian, Hanqin; Ren, Wei; Zang, Zhengchen

    2016-08-01

    A three-dimensional coupled physical-biogeochemical model was used to simulate and examine temporal and spatial variability of sea surface pCO2 in the Gulf of Mexico (GoM). The model was driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A 7-year model hindcast (2004-2010) was performed and validated against ship measurements. Model results revealed clear seasonality in surface pCO2 and were used to estimate carbon budgets in the Gulf. Based on the average of model simulations, the GoM was a net CO2 sink with a flux of 1.11 ± 0.84 × 1012 mol C yr-1, which, together with the enormous fluvial inorganic carbon input, was comparable to the inorganic carbon export through the Loop Current. Two model sensitivity experiments were performed: one without biological sources and sinks and the other using river input from the 1904-1910 period as simulated by the Dynamic Land Ecosystem Model (DLEM). It was found that biological uptake was the primary driver making GoM an overall CO2 sink and that the carbon flux in the northern GoM was very susceptible to changes in river forcing. Large uncertainties in model simulations warrant further process-based investigations.

  15. Research on Model and Related Parameters of Supercritical CO2 Injection into Depleted Reservoir

    Science.gov (United States)

    Ma, Pinghua; He, Jun

    2017-07-01

    On the basis of the research on CO2 geological storage and enhanced oil recovery(EOR) technology, a random porosity distribution model which conforms to logarithmic normal distribution was adopted in order to describe the heterogeneous characteristics of pore structure. On this basis, the two-phase flow model of CO2-formation water was established to describe the displacement process. Through the simulation of CO2 injection into depleted reservoir, it confirmed that injection point pressure was associated with the temperature and depth of the formation except heterogeneity. But the saturation distribution was greatly influenced by formation heterogeneity and depth. Thus, the space utilization of the injection layer reduced gradually with the depth increasing. The related research is important for CO2 storage, migration and evolution in depleted reservoir.

  16. Molecular dynamics simulations of CO2 formation in interstellar ices

    Science.gov (United States)

    Arasa, C.; Andersson, S.; van Dishoeck, E. F.; Kroes, G. J.

    2011-05-01

    In dense interstellar clouds where new stars and planets are formed, small dust particles of micrometer silicates are covered by ice mantles, mainly consisting of H2O and also of CO, CO2, CH4 and other molecules. A high flux of UV photons can produce several photodissociative events. Previous MD calculations of H2O ice at Tice=10-90 K show that the photodesorption of H while OH remains trapped is the main outcome following photoexcitation in the first three monolayers (MLs). On the other hand, the H and OH photofragments released following photoexcitation deeper in the ice recombine or are trapped at separate positions, and can then react with other species in the ice. We hope to present results of MD calculations performed to study the photoinduced reaction of OH with CO through photodissociation of H2O in an amorphous COad - H2O ice at 10 K. This reaction pathway is supposed to be a principle route to form CO2 in interstellar ices.

  17. Molecular dynamics simulation of the key characteristics of the supercritical CO2-pentaerythritol tetraacetate system

    Science.gov (United States)

    Lei, Peiyu; Jin, Zunlong; Liu, Hong; Wang, Dingbiao; Liu, Donglai

    2016-12-01

    Supercritical CO2 is widely used in many fields of industry. Investigation of statistical mechanics of CO2 fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO2 fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO2 are Gaussian distribution basically. The dimers' proportion of supercritical CO2 system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO2 physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO2 is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers' structure under low pressure.

  18. Simulation of seismic events induced by CO2 injection at In Salah, Algeria

    Science.gov (United States)

    Verdon, James P.; Stork, Anna L.; Bissell, Rob C.; Bond, Clare E.; Werner, Maximilian J.

    2015-09-01

    Carbon capture and storage technology has the potential to reduce anthropogenic CO2 emissions. However, the geomechanical response of the reservoir and sealing caprocks must be modelled and monitored to ensure that injected CO2 is safely stored. To ensure confidence in model results, there is a clear need to develop ways of comparing model predictions with observations from the field. In this paper we develop an approach to simulate microseismic activity induced by injection, which allows us to compare geomechanical model predictions with observed microseismic activity. We apply this method to the In Salah CCS project, Algeria. A geomechanical reconstruction is used to simulate the locations, orientations and sizes of pre-existing fractures in the In Salah reservoir. The initial stress conditions, in combination with a history matched reservoir flow model, are used to determine when and where these fractures exceed Mohr-Coulomb limits, triggering failure. The sizes and orientations of fractures, and the stress conditions thereon, are used to determine the resulting micro-earthquake focal mechanisms and magnitudes. We compare our simulated event population with observations made at In Salah, finding good agreement between model and observations in terms of event locations, rates of seismicity, and event magnitudes.

  19. 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.

  20. 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

  1. Modeling CO 2 ice clouds with a Mars Global Climate Model

    Science.gov (United States)

    Audouard, Joachim; Määttänen, Anni; Listowski, Constantino; Millour, Ehouarn; Forget, Francois; Spiga, Aymeric

    2016-10-01

    Since the first claimed detection of CO2 ice clouds by the Mariner campaign (Herr and Pimentel, 1970), more recent observations and modelling works have put new constraints concerning their altitude, region, time and mechanisms of formation (Clancy and Sandor, 1998; Montmessin et al., 2007; Colaprete et al., 2008; Määttänen et al., 2010; Vincendon et al., 2011; Spiga et al. 2012; Listowski et al. 2014). CO2 clouds are observed at the poles at low altitudes (LMD, Forget et al., 1999). It covers CO2 microphysics, growth, evolution and dynamics with a methodology inspired from the water ice clouds scheme recently included in the LMD GCM (Navarro et al., 2014).Two main factors control the formation and evolution of CO2 clouds in the Martian atmosphere: sufficient supersaturation of CO2 is needed and condensation nuclei must be available. Topography-induced gravity-waves (GW) are expected to propagate to the upper atmosphere where they produce cold pockets of supersaturated CO2 (Spiga et al., 2012), thus allowing the formation of clouds provided enough condensation nuclei are present. Such supersaturations have been observed by various instruments, in situ (Schofield et al., 1997) and from orbit (Montmessin et al., 2006, 2011; Forget et al., 2009).Using a GW-induced temperature profile and the 1-D version of the GCM, we simulate the formation of CO2 clouds in the mesosphere and investigate the sensitivity of our microphysics scheme. First results and steps towards the integration in the 3-D GCM will be presented and discussed at the conference.This work is funded by the Laboratory of Excellence ESEP.

  2. Three-dimensional microscale modelling of CO2 transport and light propagation in tomato leaves enlightens photosynthesis.

    Science.gov (United States)

    Ho, Quang Tri; Berghuijs, Herman N C; Watté, Rodrigo; Verboven, Pieter; Herremans, Els; Yin, Xinyou; Retta, Moges A; Aernouts, Ben; Saeys, Wouter; Helfen, Lukas; Farquhar, Graham D; Struik, Paul C; Nicolaï, Bart M

    2016-01-01

    We present a combined three-dimensional (3-D) model of light propagation, CO2 diffusion and photosynthesis in tomato (Solanum lycopersicum L.) leaves. The model incorporates a geometrical representation of the actual leaf microstructure that we obtained with synchrotron radiation X-ray laminography, and was evaluated using measurements of gas exchange and leaf optical properties. The combination of the 3-D microstructure of leaf tissue and chloroplast movement induced by changes in light intensity affects the simulated CO2 transport within the leaf. The model predicts extensive reassimilation of CO2 produced by respiration and photorespiration. Simulations also suggest that carbonic anhydrase could enhance photosynthesis at low CO2 levels but had little impact on photosynthesis at high CO2 levels. The model confirms that scaling of photosynthetic capacity with absorbed light would improve efficiency of CO2 fixation in the leaf, especially at low light intensity.

  3. Modeling The Anthropogenic CO2 Footprint in Europe Using a High Resolution Atmospheric Model

    Science.gov (United States)

    Liu, Yu; Gruber, Nicolas; Brunner, Dominik

    2015-04-01

    The localized nature of most fossil fuel emission sources leaves a distinct footprint on atmospheric CO2 concentrations, yet to date, most studies have used relatively coarse atmospheric transport models to simulate this footprint, causing an excess amount of spatial smoothing. In addition, most studies have considered only monthly variations in emissions, neglecting their substantial diurnal and weekly fluctuations. With the fossil fuel emission fluxes dominating the carbon balance in Europe and many other industrialized countries, it is paramount to simulate the fossil fuel footprint in atmospheric CO2 accurately in time and space in order to discern the footprint of the terrestrial biosphere. Furthermore, a good understanding of the fossil fuel footprint also provides the opportunity to monitor and verify any change in fossil fuel emission. We use here a high resolution (7 km) atmospheric model setup for central Europe based on the operational weather forecast model COSMO and simulate the atmospheric CO2 concentrations separately for 5 fossil fuel emission sectors (i.e., power generation, heating, transport, industrial processes, and rest), and for 10 different country-based regions. The emissions were based on high-resolution emission inventory data (EDGAR(10km) and MeteoTest(500m)), to which we have added detailed time functions for each process and country. The total anthropogenic CO2 footprint compares well with observational estimates based on radiocarbon (C14) and CO for a number of sites across Europe, providing confidence in the emission inventory and atmospheric transport. Despite relatively rapid atmospheric mixing, the fossil fuel footprint shows strong annual mean structures reflecting the point-source nature of most emissions. Among all the processes, the emissions from power plants dominates the fossil fuel footprint, followed by industry, while traffic emissions are less distinct, largely owing to their spatially more distributed nature. However

  4. Modeling atmospheric CO2 concentration profiles and fluxes above sloping terrain at a boreal site

    Directory of Open Access Journals (Sweden)

    T. Aalto

    2006-01-01

    Full Text Available CO2 fluxes and concentrations were simulated in the planetary boundary layer above subarctic hilly terrain using a three dimensional model. The model solves the transport equations in the local scale and includes a vegetation sub-model. A WMO/GAW background concentration measurement site and an ecosystem flux measurement site are located inside the modeled region at a hilltop and above a mixed boreal forest, respectively. According to model results, the concentration measurement at the hill site was representative for continental background. However, this was not the case for the whole model domain. Concentration at few meters above active vegetation represented mainly local variation. Local variation became inseparable from the regional signal at about 60-100 m above ground. Flow over hills changed profiles of environmental variables and height of inversion layer, however CO2 profiles were more affected by upwind land use than topography. The hill site was above boundary layer during night and inside boundary layer during daytime. The CO2 input from model lateral boundaries dominated in both cases. Daily variation in the CO2 assimilation rate was clearly seen in the CO2 profiles. Concentration difference between the hill site and the forest site was about 5ppm during afternoon according to both model and measurements. The average modeled flux to the whole model region was about 40% of measured and modeled local flux at the forest site.

  5. Assumption Centred Modelling of Ecosystem Responses to CO2 at Six US Atmospheric CO2 Enrichment Experiments.

    Science.gov (United States)

    Walker, A. P.; De Kauwe, M. G.; Medlyn, B. E.; Zaehle, S.; Luus, K. A.; Ryan, E.; Xia, J.; Norby, R. J.

    2015-12-01

    Plant photosynthetic rates increase and stomatal apertures decrease in response to elevated atmospheric CO[2] (eCO2), increasing both plant carbon (C) availability and water use efficiency. These physiological responses to eCO2 are well characterised and understood, however the ecological effects of these responses as they cascade through a suite of plant and ecosystem processes are complex and subject to multiple interactions and feedbacks. Therefore the response of the terrestrial carbon sink to increasing atmospheric CO[2] remains the largest uncertainty in global C cycle modelling to date, and is a huge contributor to uncertainty in climate change projections. Phase 2 of the FACE Model-Data Synthesis (FACE-MDS) project synthesises ecosystem observations from five long-term Free-Air CO[2] Enrichment (FACE) experiments and one open top chamber (OTC) experiment to evaluate the assumptions of a suite of terrestrial ecosystem models. The experiments are: The evergreen needleleaf Duke Forest FACE (NC), the deciduous broadleaf Oak Ridge FACE (TN), the prairie heating and FACE (WY), and the Nevada desert FACE, and the evergreen scrub oak OTC (FL). An assumption centered approach is being used to analyse: the interaction between eCO2 and water limitation on plant productivity; the interaction between eCO2 and temperature on plant productivity; whether increased rates of soil decomposition observed in many eCO2 experiments can account for model deficiencies in N uptake shown during Phase 1 of the FACE-MDS; and tracing carbon through the ecosystem to identify the exact cause of changes in ecosystem C storage.

  6. Experimental simulation of the condensation and metamorphism of seasonal CO2 condensates under martian conditions.

    Science.gov (United States)

    Grisolle, F.; Schmitt, B.; Beck, P.; Philippe, S.; Brissaud, O.

    2014-04-01

    An experimental set-up, CARBON-IR, has been developed in order to perform the condensation and metamorphism of CO2 condensates in various controlled martian conditions at, or out of, equilibrium. The sample texture is monitored and near-infrared reflectance spectra are recorded. We present a first set of experiments aimed to simulate the formation of compact translucent slabs by condensation of CO2 gas, the metamorphism of CO2 snow, as well as their sublimation.

  7. Simulating CO2 flux of three different ecosystems in ChinaFLUX based on artificial neural networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>The nonlinearity of the relationship between CO2 flux and other micrometeorological variables flux parameters limits the applicability of carbon flux models to accurately estimate the flux dynamics. However, the need for carbon dioxide (CO2) estimations covering larger areas and the limitations of the point eddy covariance technique to address this requirement necessitates the modeling of CO2 flux from other micrometeorological variables. Artificial neural networks (ANN) are used because of their power to fit highly nonlinear relations between input and output variables without explaining the nature of the phenomena. This paper applied a multilayer perception ANN technique with error back propagation algorithm to simulate CO2 flux on three different ecosystems (forest, grassland and cropland) in ChinaFLUX. Energy flux (net radiation, latent heat, sensible heat and soil heat flux) and temperature (air and soil) and soil moisture were used to train the ANN and predict the CO2 flux. Diurnal half-hourly fluxes data of observations from June to August in 2003 were divided into training, validating and testing. Results of the CO2 flux simulation show that the technique can successfully predict the observed values with R2 value between 0.75 and 0.866. It is also found that the soil moisture could not improve the simulative accuracy without water stress. The analysis of the contribution of input variables in ANN shows that the ANN is not a black box model, it can tell us about the controlling parameters of NEE in different ecosystems and micrometeorological environment. The results indicate the ANN is not only a reliable, efficient technique to estimate regional or global CO2 flux from point measurements and understand the spatiotemporal budget of the CO2 fluxes, but also can identify the relations between the CO2 flux and micrometeorological variables.

  8. 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

  9. Fast cloud adjustment to increasing CO2 in a superparameterized climate model

    Science.gov (United States)

    Wyant, Matthew C.; Bretherton, Christopher S.; Blossey, Peter N.; Khairoutdinov, Marat

    2012-05-01

    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.

  10. Modelling of Seismic and Resistivity Responses during the Injection of CO2 in Sandstone Reservoir

    Science.gov (United States)

    Omar, Muhamad Nizarul Idhafi Bin; Almanna Lubis, Luluan; Nur Arif Zanuri, Muhammad; Ghosh, Deva P.; Irawan, Sonny; Regassa Jufar, Shiferaw

    2016-07-01

    Enhanced oil recovery plays vital role in production phase in a producing oil field. Initially, in many cases hydrocarbon will naturally flow to the well as respect to the reservoir pressure. But over time, hydrocarbon flow to the well will decrease as the pressure decrease and require recovery method so called enhanced oil recovery (EOR) to recover the hydrocarbon flow. Generally, EOR works by injecting substances, such as carbon dioxide (CO2) to form a pressure difference to establish a constant productive flow of hydrocarbon to production well. Monitoring CO2 performance is crucial in ensuring the right trajectory and pressure differences are established to make sure the technique works in recovering hydrocarbon flow. In this paper, we work on computer simulation method in monitoring CO2 performance by seismic and resistivity model, enabling geoscientists and reservoir engineers to monitor production behaviour as respect to CO2 injection.

  11. Optimization of a prognostic biosphere model for terrestrial biomass and atmospheric CO2 variability

    Directory of Open Access Journals (Sweden)

    M. Saito

    2014-08-01

    Full Text Available This study investigates the capacity of a prognostic biosphere model to simulate global variability in atmospheric CO2 concentrations and vegetation carbon dynamics under current environmental conditions. Global data sets of atmospheric CO2 concentrations, above-ground biomass (AGB, and net primary productivity (NPP in terrestrial vegetation were assimilated into the biosphere model using an inverse modeling method combined with an atmospheric transport model. In this process, the optimal physiological parameters of the biosphere model were estimated by minimizing the misfit between observed and modeled values, and parameters were generated to characterize various biome types. Results obtained using the model with the optimized parameters correspond to the observed seasonal variations in CO2 concentration and their annual amplitudes in both the Northern and Southern Hemispheres. In simulating the mean annual AGB and NPP, the model shows improvements in estimating the mean magnitudes and probability distributions for each biome, as compared with results obtained using prior simulation parameters. However, the model is less efficient in its simulation of AGB for forest type biomes. This misfit suggests that more accurate values of input parameters, specifically, grid mean AGB values and seasonal variabilities in physiological parameters, are required to improve the performance of the simulation model.

  12. Development and validation of a radial inflow turbine model for simulation of the SNL S-CO2 split-flow loop.

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, R. B. (Nuclear Engineering Division)

    2012-07-31

    A one-dimensional model for a radial inflow turbine has been developed for super-critical carbon dioxide (S-CO{sub 2}) Brayton cycle applications. The model accounts for the main phenomena present in the volute, nozzle, and impeller of a single-stage turbine. These phenomena include internal losses due to friction, blade loading, and angle of incidence and parasitic losses due to windage and blade-housing leakage. The model has been added as a component to the G-PASS plant systems code. The model was developed to support the analysis of S-CO{sub 2} cycles in conjunction with small-scale loop experiments. Such loops operate at less than a MWt thermal input. Their size permits components to be reconfigured in new arrangements relatively easily and economically. However, the small thermal input combined with the properties of carbon dioxide lead to turbomachines with impeller diameters of only one to two inches. At these sizes the dominant phenomena differ from those in larger more typical machines. There is almost no treatment in the literature of turbomachines at these sizes. The present work therefore is aimed at developing turbomachine models that support the task of S-CO{sub 2} cycle analysis using small-scale tests. Model predictions were compared against data from an experiment performed for Sandia National Laboratories in the split-flow Brayton cycle loop currently located at Barber-Nichols Inc. The split-flow loop incorporates two turbo-alternator-compressor (TAC) units each incorporating a radial inflow turbine and a radial flow compressor on a common shaft. The predicted thermodynamic conditions at the outlet of the turbine on the main compressor shaft were compared with measured values at different shaft speeds. Two modifications to the original model were needed to better match the experiment data. First, a representation of the heat loss from the volute downstream of the sensed inlet temperature was added. Second, an empirical multiplicative factor was

  13. A numerical evaluation of prediction accuracy of CO2 absorber model for various reaction rate coefficients

    Directory of Open Access Journals (Sweden)

    Shim S.M.

    2012-01-01

    Full Text Available The performance of the CO2 absorber column using mono-ethanolamine (MEA solution as chemical solvent are predicted by a One-Dimensional (1-D rate based model in the present study. 1-D Mass and heat balance equations of vapor and liquid phase are coupled with interfacial mass transfer model and vapor-liquid equilibrium model. The two-film theory is used to estimate the mass transfer between the vapor and liquid film. Chemical reactions in MEA-CO2-H2O system are considered to predict the equilibrium pressure of CO2 in the MEA solution. The mathematical and reaction kinetics models used in this work are calculated by using in-house code. The numerical results are validated in the comparison of simulation results with experimental and simulation data given in the literature. The performance of CO2 absorber column is evaluated by the 1-D rate based model using various reaction rate coefficients suggested by various researchers. When the rate of liquid to gas mass flow rate is about 8.3, 6.6, 4.5 and 3.1, the error of CO2 loading and the CO2 removal efficiency using the reaction rate coefficients of Aboudheir et al. is within about 4.9 % and 5.2 %, respectively. Therefore, the reaction rate coefficient suggested by Aboudheir et al. among the various reaction rate coefficients used in this study is appropriate to predict the performance of CO2 absorber column using MEA solution. [Acknowledgement. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF, funded by the Ministry of Education, Science and Technology (2011-0017220].

  14. 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.

  15. 采用分布参数模型的CO2微通道蒸发器数值模拟%Numerical Simulation of the Carbon Dioxide Microchannel Evaporator Using Distributed Parameter Model

    Institute of Scientific and Technical Information of China (English)

    张海清; 郭蓓

    2012-01-01

    A steady state distributed parameter model for the microchannel evaporator applied in a transcritical carbon dioxide air-conditioning system was established using the FEM method. Different models of heat transfer at the refrigerant-side were compared and analyzed, and a modified heat transfer correlation was proposed. Moreover, characteristics of heat transfer and flow were analyzed under both dry and wet conditions considering the pressure losses at the inlet and outlet of the header of the evaporator. The simulation results are in reasonable agreement with the experimental data. The average relative errors for cooling capacity and refrigerant-side pressure drop are less than 8. 2% and 10% , respectively. It is likely that the present model may be used to analyze and design CO2 microchannel evaporators.%采用有限元分析方法为跨临界CO2空调系统的微通道蒸发器建立了二维分布参数仿真模型,比较分析了适用于不同制冷剂侧的换热关联式,并为此提出了一种修正的换热关联式,以期为微通道蒸发器模型能够获得很好的预测结果.模型中考虑了干、湿工况以及制冷剂进出集液管产生的压力损失对制冷剂侧换热和流动特性的影响.对比分析得出:微通道蒸发器的制冷量和压降在制冷剂侧仿真、实验的相对误差分别小于8.2%和10%,表明所建模型可作为CO2微通道蒸发器的优化设计的理论依据.

  16. A Neural Network Model for Forecasting CO2 Emission

    Directory of Open Access Journals (Sweden)

    C. Gallo

    2014-06-01

    Full Text Available Air pollution is today a serious problem, caused mainly by human activity. Classical methods are not considered able to efficiently model complex phenomena as meteorology and air pollution because, usually, they make approximations or too rigid schematisations. Our purpose is a more flexible architecture (artificial neural network model to implement a short-term CO2 emission forecasting tool applied to the cereal sector in Apulia region – in Southern Italy - to determine how the introduction of cultural methods with less environmental impact acts on a possible pollution reduction.

  17. 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...

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

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-02-01

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

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

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2011-06-01

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

  20. 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

  1. 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).

  2. Statistical Modelling of CO2 Emissions in Malaysia and Thailand

    Directory of Open Access Journals (Sweden)

    Tay Sze Hui

    2012-01-01

    Full Text Available Carbon dioxide (CO2 emissions is an environmental problem which leads to Earth’s greenhouse effect. Much concerns with carbon dioxide emissions centered around the growing threat of global warming and climate  change. This paper, however, presents a simple model development using multiple regression with interactions for estimating carbon dioxide emissions in Malaysia and Thailand. Five indicators over the period 1971-2006, namely  energy use, GDP per capita, population density, combustible renewables and waste, and CO2 intensity are used in the analysis. Progressive model selections using forward selection, backward elimination and stepwise regression are used to remove insignificant variables, with possible interactions. Model selection techniques are compared against the performance of eight criteria model selection process. Global test, Coefficient test, Wald test and Goodnessof-fit test are carried out to ensure that the best regression model is selected for further analysis. A numerical illustration is included to enhance the understanding of the whole process in obtaining the final best model.

  3. 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

  4. 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.

  5. Migration behavior of supercritical and liquid CO2 in a stratified system: Experiments and numerical simulations

    Science.gov (United States)

    Oh, Junho; Kim, Kue-Young; Han, Weon Shik; Park, Eungyu; Kim, Jeong-Chan

    2015-10-01

    Multiple scenarios of upward CO2 migration driven by both injection-induced pressure and buoyancy force were investigated in a horizontally and vertically stratified core utilizing a core-flooding system with a 2-D X-ray scanner. Two reservoir-type scenarios were considered: (1) the terrestrial reservoir scenario (10 MPa and 50°C), where CO2 exists in a supercritical state and (2) the deep-sea sediment reservoir scenario (28 MPa and 25°C), where CO2 is stored in the liquid phase. The core-flooding experiments showed a 36% increase in migration rate in the vertical core setting compared with the horizontal setting, indicating the significance of the buoyancy force under the terrestrial reservoir scenario. Under both reservoir conditions, the injected CO2 tended to find a preferential flow path (low capillary entry pressure and high-permeability (high-k) path) and bypass the unfavorable pathways, leaving low CO2 saturation in the low-permeability (low-k) layers. No distinctive fingering was observed as the CO2 moved upward, and the CO2 movement was primarily controlled by media heterogeneity. The CO2 saturation in the low-k layers exhibited a more sensitive response to injection rates, implying that the increase in CO2 injection rates could be more effective in terms of storage capacity in the low-k layers in a stratified reservoir. Under the deep-sea sediment condition, the storage potential of liquid CO2 was more than twice as high as that of supercritical CO2 under the terrestrial reservoir scenario. In the end, multiphase transport simulations were conducted to assess the effects of heterogeneity on the spatial variation of pressure buildup, CO2 saturation, and CO2 flux. Finally, we showed that a high gravity number (Ngr) tended to be more influenced by the heterogeneity of the porous media.

  6. Impact Of Three-Phase Relative Permeability and Hysteresis Models On Forecasts of Storage Associated with CO2-EOR

    Science.gov (United States)

    Jia, W.; Pan, F.; McPherson, B. J. O. L.

    2015-12-01

    Due to the presence of multiple phases in a given system, CO2 sequestration with enhanced oil recovery (CO2-EOR) includes complex multiphase flow processes compared to CO2 sequestration in deep saline aquifers (no hydrocarbons). Two of the most important factors are three-phase relative permeability and hysteresis effects, both of which are difficult to measure and are usually represented by numerical interpolation models. The purposes of this study included quantification of impacts of different three-phase relative permeability models and hysteresis models on CO2 sequestration simulation results, and associated quantitative estimation of uncertainty. Four three-phase relative permeability models and three hysteresis models were applied to a model of an active CO2-EOR site, the SACROC unit located in western Texas. To eliminate possible bias of deterministic parameters on the evaluation, a sequential Gaussian simulation technique was utilized to generate 50 realizations to describe heterogeneity of porosity and permeability, initially obtained from well logs and seismic survey data. Simulation results of forecasted pressure distributions and CO2 storage suggest that (1) the choice of three-phase relative permeability model and hysteresis model have noticeable impacts on CO2 sequestration simulation results; (2) influences of both factors are observed in all 50 realizations; and (3) the specific choice of hysteresis model appears to be somewhat more important relative to the choice of three-phase relative permeability model in terms of model uncertainty.

  7. 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)

    P. Béziat

    2011-03-01

    Full Text Available 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

  8. Numerical simulation of CO2 geological storage in saline aquifers - case study of Utsira formation

    Directory of Open Access Journals (Sweden)

    Zheming Zhang, Ramesh K. Agarwal

    2014-01-01

    Full Text Available CO2 geological storage (CGS is one of the most promising technologies to address the issue of excessive anthropogenic CO2 emissions in the atmosphere due to fossil fuel combustion for electricity generation. In order to fully exploit the storage potential, numerical simulations can help in determining injection strategies before the deployment of full scale sequestration in saline aquifers. This paper presents the numerical simulations of CO2 geological storage in Utsira saline formation where the sequestration is currently underway. The effects of various hydrogeological and numerical factors on the CO2 distribution in the topmost hydrogeological layer of Utsira are discussed. The existence of multiple pathways for upward mobility of CO2 into the topmost layer of Utsira as well as the performance of the top seal are also investigated.

  9. Numerical simulation of CO2 geological storage in saline aquifers – case study of Utsira formation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zheming; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)

    2013-07-01

    CO2 geological storage (CGS) is one of the most promising technologies to address the issue of excessive anthropogenic CO2 emissions in the atmosphere due to fossil fuel combustion for electricity generation. In order to fully exploit the storage potential, numerical simulations can help in determining injection strategies before the deployment of full scale sequestration in saline aquifers. This paper presents the numerical simulations of CO2 geological storage in Utsira saline formation where the sequestration is currently underway. The effects of various hydrogeological and numerical factors on the CO2 distribution in the topmost hydrogeological layer of Utsira are discussed. The existence of multiple pathways for upward mobility of CO2 into the topmost layer of Utsira as well as the performance of the top seal are also investigated.

  10. Shock compression of CO2: experiments on Z and first-principles simulations

    Science.gov (United States)

    Mattsson, T. R.; Root, S.; Shulenburger, L.; Cochrane, K. R.

    2011-06-01

    The principal Hugoniot for CO2 is known up to 75 GPa and it displays a plateau in shock pressure interpreted as the result of dissociation. To confidently model the structure of gas-giant planets and the deep carbon cycle of the earth it is important to accurately know the properties of CO2 at even higher pressures. We present results from flyer-plate experiments on Sandia's Z-machine providing data for CO2 between 150 and 600 GPa. We also present Density Functional Theory (DFT) based simulations up to 500 GPa, including a chemical composition analysis. Quantum Monte Carlo (QMC) is applied to assess the accuracy of exchange-correlation functionals. We conclude that the plateau in shock pressure at 50 GPa is consistent with dissociation. Beyond 3.5 g/cm3 density, the shock pressure raises rapidly due to completed dissociation. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corp., a subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  11. Stochastic Modeling of CO2 Migrations and Chemical Reactions in Deep Saline Formations

    Science.gov (United States)

    Ni, C.; Lee, I.; Lin, C.

    2013-12-01

    Carbon capture and storage (CCS) has been recognized the feasible technology that can significant reduce the anthropogenic CO2 emissions from large point sources. The CO2 injection in geological formations is one of the options to permanently store the captured CO2. Based on this concept a large number of target formations have been identified and intensively investigated with different types of techniques such as the hydrogeophysical experiments or numerical simulations. The numerical simulations of CO2 migrations in saline formations recently gather much attention because a number of models are available for this purpose and there are potential sites existing in many countries. The lower part of Cholan Formation (CF) near Changhua Coastal Industrial Park (CCIP) in west central Taiwan was identified the largest potential site for CO2 sequestration. The top elevations of the KF in this area varies from 1300 to 1700m below the sea level. Laboratory experiment showed that the permeability of CF is 10-14 to 10-12 m2. Over the years the offshore seismic survey and limited onshore borehole logs have provided information for the simulation of CO2 migration in the CF although the original investigations might not focus on the purpose of CO2 sequestration. In this study we modify the TOUGHREACT model to consider the small-scale heterogeneity in target formation and the cap rock of upper CF. A Monte Carlo Simulation (MCS) approach based on the TOUGHREACT model is employed to quantify the effect of small-scale heterogeneity on the CO2 migrations and hydrochemical reactions in the CF. We assume that the small-scale variability of permeability in KF can be described with a known Gaussian distribution. Therefore, the Gaussian type random field generator such as Sequential Gaussian Simulation (SGSIM) in Geostatistical Software Library (GSLIB) can be used to provide the random permeability realizations for the MCS. A variety of statistical parameters such as the variances and

  12. 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 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 to reduce the gap between the field and lab rates by about two orders of magnitude at elevated temperatures of 200-300 oC. Currently, we are using Si isotopes as a new tool to unravel the coupled reactions in ambient temperature laboratory experiments. These new experimental data, together with coupled reactive mass transport modeling

  13. 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

  14. 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.

  15. The South Residual CO 2 Cap on Mars: Investigations with a Mars Global Climate Model

    Science.gov (United States)

    Kahre, Melinda A.; Dequaire, Julie; Hollingsworth, Jeffery L.; Haberle, Robert

    2016-10-01

    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 could 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. Our current work builds on these initial investigations with a version of the NASA Ames Mars Global Climate Model (GCM) that includes a sophisticated CO2 cloud microphysical scheme. Processes of cloud nucleation, growth, sedimentation, and radiative effects are accounted for. Simulated results thus far agree well with the Colaprete et al. study—the zonally asymmetric nature of the atmospheric circulation produces enhanced snowfall over the residual cap hemisphere throughout much of the winter season. However, the predicted snowfall patterns vary significantly with season throughout the cap growth and recession phases. We will present a detailed analysis of the seasonal evolution of the predicted atmospheric circulation and snowfall patterns to more fully evaluate the hypothesis that the atmosphere controls the placement of the south residual cap.

  16. Intercomparison of numerical simulation codes for geologic disposal of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, Karsten; Garcia, Julio; Kovscek, Tony; Oldenburg, Curt; Rutqvist, Jonny; Steefel, Carl; Xu, Tianfu

    2002-11-27

    Numerical simulation codes were exercised on a suite of eight test problems that address CO2 disposal into geologic storage reservoirs, including depleted oil and gas reservoirs, and brine aquifers. Processes investigated include single- and multi-phase flow, gas diffusion, partitioning of CO2 into aqueous and oil phases, chemical interactions of CO2 with aqueous fluids and rock minerals, and mechanical changes due to changes in fluid pressures. Representation of fluid properties was also examined. In most cases results obtained from different simulation codes were in satisfactory agreement, providing confidence in the ability of current numerical simulation approaches to handle the physical and chemical processes that would be induced by CO2 disposal in geologic reservoirs. Some discrepancies were also identified and can be traced to differences in fluid property correlations, and space and time discretization.

  17. 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

  18. Coupled Reactive Transport Modeling of CO2 Injection in Mt. Simon Sandstone Formation, Midwest USA

    Science.gov (United States)

    Liu, F.; Lu, P.; Zhu, C.; Xiao, Y.

    2009-12-01

    CO2 sequestration in deep geological formations is one of the promising options for CO2 emission reduction. While several large scale CO2 injections in saline aquifers have shown to be successful for the short-term, there is still a lack of fundamental understanding on key issues such as CO2 storage capacity, injectivity, and security over multiple spatial and temporal scales that need to be addressed. To advance these understandings, we applied multi-phase coupled reactive mass transport modeling to investigate the fate of injected CO2 and reservoir responses to the injection into Mt. Simon Formation. We developed both 1-D and 2-D reactive transport models in a radial region of 10,000 m surrounding a CO2 injection well to represent the Mt. Simon sandstone formation, which is a major regional deep saline reservoir in the Midwest, USA. Supercritical CO2 is injected into the formation for 100 years, and the modeling continues till 10,000 years to monitor both short-term and long-term behavior of injected CO2 and the associated rock-fluid interactions. CO2 co-injection with H2S and SO2 is also simulated to represent the flue gases from coal gasification and combustion in the Illinois Basin. The injection of CO2 results in acidified zones (pH ~3 and 5) adjacent to the wellbore, causing progressive water-rock interactions in the surrounding region. In accordance with the extensive dissolution of authigenic K-feldspar, sequential precipitations of secondary carbonates and clay minerals are predicted in this zone. The vertical profiles of CO2 show fingering pattern from the top of the reservoir to the bottom due to the density variation of CO2-impregnated brine, which facilitate convection induced mixing and solubility trapping. Most of the injected CO2 remains within a radial distance of 2500 m at the end of 10,000 years and is sequestered and immobilized by solubility and residual trapping. Mineral trapping via secondary carbonates, including calcite, magnesite

  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. Molecular Simulation on Microstructure of Ionic Liquids in Capture of CO2

    Institute of Scientific and Technical Information of China (English)

    YUE Zhen-uo; LIU Xiao-min; ZHAO Yu-ling; ZHANG Xiao-chun; LU Xing-mei; ZHANG Suo-jiang

    2011-01-01

    Molecular dynamic simulation is used to study the microstructure of four kinds of ionic liquids (ILs),[Emim]PF6,[Emim][Tf2N],[PC6,6,6,14]PF6 and [PC6,6,6,14][Tf2N] in the capture process of CO2.Radial distribution function (RDF) and spatial distribution function (SDF) are used to analyze the microscopic properties of these systems.The calculated results show that the space distribution of CO2 around ILs determines the capability of ionic liquids for capturing CO2.Based on the analysis of SDF,CO2 and PF6- are overlapped partially around [Emim]+ in [Emim]PF6-CO2 mixture.When the anion is [Tf2N]-,cations are mainly distributed on one side of [Tf2N]- near N atom,and CO2 is concentrated on two sides near the fluoroalkylgroup (-CF3),and there is little overlapped district between cation and CO2.In [PC6,6,6,14]PF6-CO2 mixture,layered structure is found and CO2 is much nearer to PF6- than [PC6,6,6,14]+.Based on the analysis of RDF,in the phosphonium-based ILs,the highest distribution densities of anions and CO2 around cations are about 6 and 3 times as their average ones respectively,while in the imidazolium-based ILs,they are about 3 and 2 respectively,this means that the distributions of CO2 and anions around the imidazolium-based ILs are more evenly distributed than those around the phosphonium-bascd ILs.

  1. 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.

  2. Atomistic simulations of CO2 and N2 within cage-type silica zeolites.

    Science.gov (United States)

    Madison, Lindsey; Heitzer, Henry; Russell, Colin; Kohen, Daniela

    2011-03-01

    The behavior of CO(2) and N(2), both as single components and as binary mixtures, in two cage-type silica zeolites was studied using atomistic simulations. The zeolites considered, ITQ-3 and paradigm cage-type zeolite ZK4 (the all-silica analog of LTA), were chosen so that the principles illustrated can be generalized to other adsorbent/adsorbate systems with similar topology and types of interactions. N(2) was chosen both because of the potential uses of N(2)/CO(2) separations and because it differs from CO(2) most significantly in the magnitude of its Coulombic interactions with zeolites. Despite similarities between N(2) and CO(2) diffusion in other materials, we show here that the diffusion of CO(2) within cage-type zeolites is dominated by an energy barrier to diffusion located at the entrance to the narrow channels connecting larger cages. This barrier originates in Coulombic interactions between zeolites and CO(2)'s quadrupole and results in well-defined orientations for the diffusing molecules. Furthermore, CO(2)'s favorable electrostatic interactions with the zeolite framework result in preferential binding in the windows between cages. N(2)'s behavior, in contrast, is more consistent with that of molecules previously studied. Our analysis suggests that CO(2)'s behavior might be common for adsorbates with quadrupoles that interact strongly with a material that has narrow windows between cages.

  3. Modeling post-combustion CO2 capture with amine solvents

    OpenAIRE

    Léonard, Grégoire; Heyen, Georges

    2010-01-01

    In order to avoid the emission of large amounts of greenhouse gas, CO2 capture in fossil fuel power plants and subsequent underground CO2 sequestration is studied. The capture occurs by reactive CO2 absorption into chemical solvent systems at moderate temperature (~50°C) followed by solvent regeneration at higher temperature (~120°C). So far, the most employed solvent for acid gas capture is monoethanolamine (MEA). One main drawback of this technology is the high energy consumption necessary ...

  4. Modeling of adsorption of CO2 in the deformed pores of MIL-53(Al).

    Science.gov (United States)

    Dundar, Ege; Chanut, Nicolas; Formalik, Filip; Boulet, Pascal; Llewellyn, Philip L; Kuchta, Bogdan

    2017-04-01

    Molecular simulations were performed to predict CO2 adsorption in flexible metal-organic frameworks (MOFs). A generic force field was fitted to our experimental data to describe the non-bonded (electrostatic and van der Waals) interactions between CO2 molecules and the large pore (lp) and narrow pore (np) forms of the MIL-53(Al) framework. With the new validated force field, it is possible to predict CO2 uptake and enthalpy of adsorption at various applied external pressures that will modify the structure's pore configuration and allow us to have more control over the adsorption/desorption process. A sensitivity analysis of MOF adsorption properties to the variation of the force field parameters was also intensively studied. It was shown that relatively small variations of the adsorbate gas model can improve the quality of the numerical predictions of the experimental data. However, the variations must be kept small enough to not modify the properties of the gas itself.

  5. Weathering by tree-root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Science.gov (United States)

    Quirk, J.; Leake, J. R.; Banwart, S. A.; Taylor, L. L.; Beerling, D. J.

    2014-01-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 concentrations ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation. However, the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  6. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Science.gov (United States)

    Quirk, J.; Leake, J. R.; Banwart, S. A.; Taylor, L. L.; Beerling, D. J.

    2013-10-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  7. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Directory of Open Access Journals (Sweden)

    J. Quirk

    2013-10-01

    Full Text Available Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM and ectomycorrhizal (EM fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

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

    KAUST Repository

    Saad, Bilal M.

    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.

  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. A vertically integrated model with vertical dynamics for CO2 storage

    Science.gov (United States)

    Guo, Bo; Bandilla, Karl W.; Doster, Florian; Keilegavlen, Eirik; Celia, Michael A.

    2014-08-01

    Conventional vertically integrated models for CO2 storage usually adopt a vertical equilibrium (VE) assumption, which states that due to strong buoyancy, CO2 and brine segregate quickly, so that the fluids can be assumed to have essentially hydrostatic pressure distributions in the vertical direction. However, the VE assumption is inappropriate when the time scale of fluid segregation is not small relative to the simulation time. By casting the vertically integrated equations into a multiscale framework, a new vertically integrated model can be developed that relaxes the VE assumption, thereby allowing vertical dynamics to be modeled explicitly. The model maintains much of the computational efficiency of vertical integration while allowing a much wider range of problems to be modeled. Numerical tests of the new model, using injection scenarios with typical parameter sets, show excellent behavior of the new approach for homogeneous geologic formations.

  11. Reactive transport modeling of CO2 injection in the Farnsworth, Texas hydrocarbon field

    Science.gov (United States)

    Ahmmed, B.; Appold, M. S.; McPherson, B. J. O. L.; Grigg, R.; White, M. D.

    2014-12-01

    The Farnsworth hydrocarbon field in northern Texas has been an experimental site for CO2 sequestration and enhanced oil recovery for the U.S. Department of Energy-sponsored Southwest Partnership (SWP) since April, 2013. CO2 is to be injected into the Pennsylvanian Morrow Sandstone at a rate of 200,000 tonnes per year for at least five years. The Morrow is a quartz-rich sandstone that lies at a depth of about 2400 m. Pore water in the Morrow has a total dissolved solids content of about 3600 mg/L dominated by Na, Cl, bicarbonate, and Ca. A reactive solute transport model was constructed for a 1700 × 1700 × 95 m volume using the TOUGHREACT software and the ECO2N equation of state for aqueous brine and CO2. Simulations were carried out to 100 years. The results showed immiscible CO2 gas to be concentrated in a lateral plume extending radially from the well screen, its ascent impeded by vigorous lateral groundwater flow in the more permeable upper Morrow. CO2 was much more widespread in aqueous solution, lowering pH throughout much of the model volume after 100 years, to a minimum of about 4.7. The low reactivity of the Morrow Sandstone due to its quartz-rich matrix and dilute pore fluid resulted in little mineral precipitation or dissolution, with net volume changes for any mineral no higher than order 10-4. The simulations predicted net dissolution of albite, calcite, and chlorite, and net precipitation of dawsonite, illite, and magnesite. The Morrow matrix was predicted to undergo slight net dissolution overall, resulting in porosity increases of up to 0.01%, suggesting that the Morrow would be resistant to significant changes in hydraulic properties as a result of the proposed amount of CO2 injection. For the 100 year simulation times calculated thus far, only a small fraction of the injected CO2 would be sequestered as carbonate minerals, with most of the injected CO2 dissolved in the aqueous phase.

  12. Numerical simulation and experimental verification of effect of CO2 enrichment on flow field of greenhouse%增施CO2气肥对温室流场影响的数值模拟及验证

    Institute of Scientific and Technical Information of China (English)

    刘妍华; 曾志雄; 郭嘉明; 吕恩利; 孟庆林

    2015-01-01

    Carbon dioxide (CO2) is one of the important raw materials for photosynthesis of crops in greenhouse, which can increase the harvest of the crops. In order to analyze the performance of CO2 fertilizer enrichment, this paper took indoor environment of greenhouse as the research object, and by means of unstructured mesh generation method, a two-dimensional turbulence computational model of greenhouse was built by ICEM CFD (the integrated computer engineering and manufacturing code for computational fluid dynamics) technique. After building 7532 triangle/quadrangle meshes, the skewness of mesh model was less than 0.75. To solve two-dimensional computational model of greenhouse, the CFD software FLUENT and the SIMPLE algorithm were used. Meanwhile, the porous model, the DO (discrete ordinates) model and thek-ε model were adopted. Governing equations of finite volume method were employed, including mass, momentum and energy conservation equations. In computational model, CO2 enriching inlet was set with the condition of mass flow inlet while outlet was set with the condition of pressure outlet through pre-calculation. And crop area was defined as porous material with the porosity of 0.8. Adopting steady-state solver to operate, environmental parameters such as indoor temperature, nitrogen (N2) concentration, oxygen (O2) concentration and CO2concentration should be initialized when flow field of greenhouse was stable. Then transient solver was needed to numerical simulation when acceleration of gravity was 9.8 m/s2 and step size was 0.01 s. By such methods, the effects of CO2jetting height, enriching flow speed and other factors on CO2 enrichment property were computed while the change of CO2concentration and distribution regularities were studied. After the simulations, some results were obtained. CO2 enrichment process had little effect on temperature of crop area, and both temperature distribution and air velocity distribution of crop area were uniform. As CO2

  13. Pore-scale Simulations of Capillary Trapping of Supercritical CO2 after Multiple Drainage and Imbibition Cycles

    Science.gov (United States)

    Schaap, M. G.

    2015-12-01

    Carbon capture and storage (CCS) of carbon dioxide emissions generated by production or combustion of fossil fuels is a technologically viable means to reduce the build-up of CO2 in the atmosphere and oceans. On a fundamental level, capillary trapping of scCO2 is a pore-scale process that shares mechanisms that are relevant, for example in oil recovery and remediation of NAPL-contaminated aquifers. Capillary trapping of scCO2 differs rather significantly from trapping of oil recovery and NAPL remediation in that the goal is to maximize the amount of NWP storage, whereas the objective of the other applications is to minimize the amount of residual NWP. This difference makes research into capillary trapping of scCO2 unique, but also complex because scCO2 phase properties (e.g. viscosity, density, and interfacial tension) exhibit large shifts with pressure and temperature which can strongly alter the trapping potential and efficiency. In this presentation we compare direct pore-scale observations of the Brine-CO2 drainage and imbibition process with lattice Boltzmann model simulations. The observations were conducted with the synchrotron-based x-ray microtomography facility at the Advanced Photon Source (APS) at Argonne National Laboratory using a novel x-ray compatible, high-pressure, elevated temperature setup. The "large" volumes (~1200 mm3; 6.3 mm diameter and 40 mm in length) were segmented into solid phase (Bentheimer Sandstone), Brine (KI, 1140 kg/m3) and scCO2. We will present LB simulations of small (64^3 voxels) and large sections of the scanned cores with a simple Shan-Chen-type model and a more advanced Equation of State-type model and compare model results to pressure and CO2 saturation levels that were observed for the CO2 invasion and Brine re-imbibition process. We will present results for the smaller sections under multiple drainage and imbibition cycles to investigate whether this will lead to enhanced trapping of scCO2 as found in earlier research.

  14. Monte Carlo simulations of high-pressure phase equilibria of CO2-H2O mixtures.

    Science.gov (United States)

    Liu, Yang; Panagiotopoulos, Athanassios Z; Debenedetti, Pablo G

    2011-05-26

    Histogram-reweighting grand canonical Monte Carlo simulations were used to obtain the phase behavior of CO(2)-H(2)O mixtures over a broad temperature and pressure range (50 °C ≤ T ≤ 350 °C, 0 ≤ P ≤ 1000 bar). We performed a comprehensive test of several existing water (SPC, TIP4P, TIP4P2005, and exponential-6) and carbon dioxide (EPM2, TraPPE, and exponential-6) models using conventional Lorentz-Berthelot combining rules for the unlike-pair parameters. None of the models we studied reproduce adequately experimental data over the entire temperature and pressure range, but critical assessments were made on the range of T and P where particular model pairs perform better. Away from the critical region (T ≤ 250 °C), the exponential-6 model combination yields the best predictions for the CO(2)-rich phase, whereas the TraPPE/TIP4P2005 model combination provides the most accurate coexistence composition and pressure for the H(2)O-rich phase. Near the critical region (250 °C < T ≤ 350 °C), the critical points are not accurately estimated by any of the models studied, but the exponential-6 models are able to qualitatively capture the critical loci and the shape of the phase envelopes. Local improvements can be achieved at specific temperatures by introducing modification factors to the Lorentz-Berthelot combining rules, but the modified combining rule is still not able to achieve global improvements over the entire temperature and pressure range. Our work points to the challenge and importance of improving current atomistic models so as to accurately predict the phase behavior of this important binary mixture.

  15. 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.

  16. Quantification of Transport Model Error Impacts on CO2 Inversions Using NASA's GEOS-5 GCM

    Science.gov (United States)

    Ott, L.; Pawson, S.; Weir, B.

    2014-12-01

    Remote sensing observations of CO2 offer the opportunity to reduce uncertainty in global carbon flux estimates. However, a number of studies have shown that inversion flux estimates are strongly influenced by errors in model transport. We will present results from modeling studies designed to quantify how such errors influence simulations of surface and column CO2 mixing ratios. These studies were conducted using the Goddard Earth Observing System, version 5 (GEOS-5) Atmospheric General Circulation Model (AGCM) and the implementation of a suite of tracers associated with errors in boundary layer, convective, and large scale transport. Unlike traditional tagged tracers which are emitted by a certain process or region, error tracers are emitted as air parcels are transported through the atmosphere. The magnitude of error tracer emissions is based on previously published ensembles of AGCM simulations with perturbations to subgrid convective and boundary layer transport, and on comparisons of several reanalysis products to estimate errors in large scale wind fields. Transport error tracers are simulated with several different e-folding lifetimes (e.g. 1, 4, 10, and 30 day) to examine differences between transient and persistent model errors. This quantification of transport error is then used in an illustrative Bayesian synthesis inversion to demonstrate how transport errors influence surface CO2 mixing ratios and how this translates into inferred biosphere flux error.

  17. Assessment of model estimates of land–atmosphere CO2 exchange across Northern Eurasia

    Directory of Open Access Journals (Sweden)

    M. A. Rawlins

    2015-02-01

    Full Text Available 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 dynamics 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 were conducted over the 1960–2009 record and 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 show the timing of peak GPP to be well simulated. Modest overestimates in model GPP and ER are also found, which are relatively higher for two boreal forest validation sites than the two tundra sites. Across the suite of model simulations, 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 ten 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 ten years, contributing to soil carbon storage gains, while model mean residence time for soil organic carbon decreased by 10% (−5 to −16%. This suggests that inputs to the soil carbon pool exceeded losses, resulting in a net gain amid a decrease in residence time. Our analysis points to improvements in model elements controlling vegetation

  18. Application of numerical simulation to pilot project of CO2 geological sequestration%数值模拟在CO2地质封存示范项目中的应用

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    The geological sequestration of CO2 in deep saline aquifer is an effective countermeasure for reducing global warming and greenhouse effect. Based on the Shenhua Ordos CO2 capture and storage (CCS) pilot project, the behavior of CO2 in deep saline aquifers is investigated. The transport process of CO2 fluid, the pressure buildup of system and the reserves potential of sequestration are analyzed. This model can provide technological support and save human and financial resources for Shenhua CCS engineering project. First, the model is calibrated by comparing simulated results and measured pressure values. The suitable pressure curve is obtained and the main hydrological parameters are determined at this stage. Then an assumption of CO2 continuing injection for 3 years is simulated based on the former model. The CO2 diffusion, solution behavior, pressure variation and total reserves of strata are analyzed. The conclusions are drawn as follows: the largest distance of CO2 migration is about 350 m; hydraulic fracturing can improve CO2 injectivity obviously; cap rock can effectively prevent the escape of CO2. Simulation results demonstrate that even though the deep saline aquifers of Ordos basin has low penetrability, it is also suitable for CO2 sequestration.%  CO2深部咸水层地质封存被认为是减缓温室效应的一种有效的工程技术手段。针对神华鄂尔多斯105 t/a CO2捕集与封存(CCS)示范项目,用数值模拟方法对CO2在地层中的运移过程进行了详细地刻画,分析了CO2的流动迁移、地层压力积聚过程及地层封存潜力。数值模型不但可以为工程的顺利进行提供技术支撑,而且可以节省人力财力。首先,根据实际监测数据对模拟参数进行校准,得到了合适的压力拟合曲线,确定了主要的水文地质参数。然后,对为期3 a的CO2续注工程进行预测,详细分析了CO2的晕扩散、溶解情况、地层压力变化情况、储层封存潜

  19. A multi-scale model for CO2 sequestration enhanced coalbed methane recovery

    Institute of Scientific and Technical Information of China (English)

    G.X.WANG; X.R.WEI; V.RUDOLPH; C.T.WEI; Y.QIN

    2009-01-01

    This paper presents a multi-scale model to simulate the multicomponent gas diffusion and flow in bulk coals for CO2 sequestration enhanced coalbed methane recovery. The model is developed based on a bi-dispersed structure model by assuming that coal con-sists of microporous micro-particles, meso/macro-pores and open microfractures. The bi-disperse diffusion theory and the Maxwell-Stefan approach were incorporated in the model, providing an improved simulation of the CH4-CO2/CH4-N2 counter diffusion dynamics. In the model,the counter diffusion process is numerically coupled with the flow of the mixture gases occurring within macro-pores or fractures in coal so as to account for the interaction between diffusion and flow in gas transport through coals.The model was validated by both experimental data from literature and our CO2 flush tests, and shows an excellent agreement with the experiments. The results reveal that the gas diffusivities, in particular the micro-pore diffusivities are strongly concentration-dependent.

  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. Melt focusing and CO2 extraction at mid-ocean ridges: simulations of reactive two-phase flow

    Science.gov (United States)

    Keller, T.; Katz, R. F.; Hirschmann, M. M.

    2016-12-01

    The deep CO2 cycle is the result of fluxes between near-surface and mantle reservoirs. Outgassing from mid-ocean ridges is one of the primary fluxes of CO2 from the asthenosphere into the ocean-atmosphere reservoir. Focusing of partial melt to the ridge axis crucially controls this flux. However, the role of volatiles, in particular CO2 and H2O, on melt transport processes beneath ridges remains poorly understood. We investigate this transport using numerical simulations of two-phase, multi-component magma/mantle dynamics. The phases are solid mantle and liquid magma; the components are dunite, MORB, hydrated basalt, and carbonated basalt. These effective components capture accepted features of mantle melting with volatiles. The fluid-dynamical model is McKenzie's formulation [1], while melting and reactive transport use the R_DMC method [2,3]. Our results indicate that volatiles cause channelized melt transport, which leads to significant variability in volume and composition of focused melt. The volatile-induced expansion of the melting regime at depth, however, has no influence on melt focusing; distal volatile-rich melts are not focused to the axis. Up to 50% of these melts are instead emplaced along the oceanic LAB. There, crystallization of accumulated melt leads to enrichment of CO2 and H2O in the deep lithosphere, which has implications for LAB rheology and volatile recycling by subduction. Results from a suite of simulations, constrained by catalogued observational data [4,5,6] enable predictions of global MOR CO2 output. By combining observational constraints with self-consistent numerical simulations we obtain a range of CO2 output from the global ridge system of 28-110 Mt CO2/yr, corresponding to mean CO2 contents of 50-200 ppm in the mantle. REFERENCES[1] McKenzie (1984), doi:10.1093/petrology/25.3.713.[2] Rudge, Bercovici & Spiegelman (2011), doi:10.1111/j.1365-246X.2010.04870.x.[3] Keller & Katz (2016), doi:10.1093/petrology/egw030.[4] Dalton

  2. Preliminary reactive geochemical transport simulation study on CO2 geological sequestration at the Changhua Coastal Industrial Park Site, Taiwan

    Science.gov (United States)

    Sung, R.; Li, M.

    2013-12-01

    Mineral trapping by precipitated carbonate minerals is one of critical mechanisms for successful long-term geological sequestration (CGS) in deep saline aquifer. Aquifer acidification induced by the increase of carbonic acid (H2CO3) and bicarbonate ions (HCO3-) as the dissolution of injected CO2 may induce the dissolution of minerals and hinder the effectiveness of cap rock causing potential risk of CO2 leakage. Numerical assessments require capabilities to simulate complicated interactions of thermal, hydrological, geochemical multiphase processes. In this study, we utilized TOUGHREACT model to demonstrate a series of CGS simulations and assessments of (1) time evolution of aquifer responses, (2) migration distance and spatial distribution of CO2 plume, (3) effects of CO2-saline-mineral interactions, and (4) CO2 trapping components at the Changhua Costal Industrial Park (CCIP) Site, Taiwan. The CCIP Site is located at the Southern Taishi Basin with sloping and layered heterogeneous formations. At this preliminary phase, detailed information of mineralogical composition of reservoir formation and chemical composition of formation water are difficult to obtain. Mineralogical composition of sedimentary rocks and chemical compositions of formation water for CGS in deep saline aquifer from literatures (e.g. Xu et al., 2004; Marini, 2006) were adopted. CGS simulations were assumed with a constant CO2 injection rate of 1 Mt/yr at the first 50 years. Hydrogeological settings included porosities of 0.103 for shale, 0.141 for interbedding sandstone and shale, and 0.179 for sandstone; initial pore pressure distributions of 24.5 MPa to 28.7 MPa, an ambient temperature of 70°C, and 0.5 M of NaCl in aqueous solution. Mineral compositions were modified from Xu et al. (2006) to include calcite (1.9 vol. % of solid), quartz (57.9 %), kaolinite (2.0 %), illite (1.0 %), oligoclase (19.8 %), Na-smectite (3.9 %), K-feldspar (8.2 %), chlorite (4.6 %), and hematite (0.5 %) and were

  3. 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.

  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. 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 %.

  6. Molecular simulation study of adsorption and diffusion on silicalite for a benzene/CO2 mixture.

    Science.gov (United States)

    Yue, Xiaopeng; Yang, Xiaoning

    2006-03-28

    The adsorption and diffusion of a binary mixture of supercritical CO2 and benzene on silicalite (MFI-type) have been studied through the grand canonical Monte Carlo and molecular dynamics (MD) simulations. The adsorption behavior of pure CO2 on silicalite was discussed in detail from the adsorption isotherms, adsorption sites, interaction energies, and isosteric heats of adsorption. For the mixture, the influences of temperature, pressure and composition on the adsorption isotherms have been examined. The adsorption site behavior of the mixture has been analyzed, and benzene molecules get adsorbed preferentially in the more spacious channel intersection positions. These simulation results suggest that SC-CO2 fluid can be used as an efficient desorbent of larger aromatics in the zeolite material. The diffusion characteristic for the benzene/CO2 mixture was studied on the basis of MD simulation. It was found that the large coadsorbed benzene molecule has a pronounced effect on the CO2 diffusion in the mixture, while the mobility of benzene molecules is very small due to geometrical restrictions.

  7. Climate and CO2 modulate the C3/C4 balance and δ13C signal in simulated vegetation

    Directory of Open Access Journals (Sweden)

    D. Jolly

    2009-08-01

    Full Text Available Climate and atmospheric CO2 effects on the balance between C3 and C4 plants have received conflicting interpretations based on the analysis of carbon isotopic fractionation (δ13C in sediments. But, climate and CO2 effects on the C3/C4 balance and δ13C signal are rarely addressed together. Here, we use a process-based model (BIOME4 to disentangle these effects. We simulated the vegetation response to climate and CO2 atmospheric concentration (pCO2 in two sites in which vegetation changed oppositely, with respect to C3 and C4 plants abundance, during the Last Glacial Maximum to Holocene transition. The C3/C4 balance and δ13C signal were primarily sensitive to temperature and CO2 atmospheric partial pressure. The simulated variations were in agreement with patterns observed in palaeorecords. Water limitation favoured C4 plants in case of large negative deviation in rainfall. Although a global parameter, pCO2 affected the δ13C signal differently from one site to the other because of its effects on the C3/C4 balance and on carbon isotopic fractionation in C3 and C4 plants. Simulated Plant functional types (PFT also differed in their composition and response from one site to the other. The C3/C4 balance involved different competing C3 and C4 PFT, and not homogeneous C3 and C4 poles as often assumed. Process-based vegetation modelling emphasizes the need to account for multiple factors when a palaeo-δ13C signal is used to reconstruct the C3/C4 balance.

  8. Climate and CO2 modulate the C3-C4 balance and δ13C signal in simulated vegetation

    Directory of Open Access Journals (Sweden)

    D. Jolly

    2009-03-01

    Full Text Available Fossil pollen data and δ13C measurements from cores collected in peatbogs or lakes have shown major changes in the terrestrial vegetation during Late Quaternary. Although the effect of climate on the C3-C4 balance has been discussed for 50 years, the impact of a low atmospheric CO2 during the Last Glacial Maximum (LGM was emphasized recently and conflicting evidence exists. In this paper, we use a physiologically-based biome model (BIOME4 in an iterative mode to simulate vegetation response to changing mean climate conditions and atmospheric CO2 partial pressure (pCO2. In particular, we investigate the transition from LGM to present conditions in two sites which changed from either a C4- or a C3-dominated vegetation to the opposite pole, respectively at Kuruyange (Burundi and Lingtaï (Central Loess Plateau, China. The response of the C3-C4 balance and δ13C signal in the simulated vegetation are investigated. The results show that the vegetation is primarily sensitive to temperature and pCO2. Rainfall impacted the simulated variables below a threshold which decreased with higher pCO2. Climate and pCO2 interacted differently between the two sites showing indirect effects on the δ13C signal. Moreover, the plant functional types (PFTs differed in their composition and in their response between the two sites, emphasizing that the competition between C3 and C4 plants cannot be hardly considered as a simple binary scheme. Our results confirm the advantages of using process-based models to understand past vegetation changes and the need to take account of multiple drivers when the C3-C4 balance is reconstructed from a palaeo-δ13C signal.

  9. Compressibility, thermal expansion coefficient and heat capacity of CH4 and CO2 hydrate mixtures using molecular dynamics simulations.

    Science.gov (United States)

    Ning, F L; Glavatskiy, K; Ji, Z; Kjelstrup, S; H Vlugt, T J

    2015-01-28

    Understanding the thermal and mechanical properties of CH4 and CO2 hydrates is essential for the replacement of CH4 with CO2 in natural hydrate deposits as well as for CO2 sequestration and storage. In this work, we present isothermal compressibility, isobaric thermal expansion coefficient and specific heat capacity of fully occupied single-crystal sI-CH4 hydrates, CO2 hydrates and hydrates of their mixture using molecular dynamics simulations. Eight rigid/nonpolarisable water interaction models and three CH4 and CO2 interaction potentials were selected to examine the atomic interactions in the sI hydrate structure. The TIP4P/2005 water model combined with the DACNIS united-atom CH4 potential and TraPPE CO2 rigid potential were found to be suitable molecular interaction models. Using these molecular models, the results indicate that both the lattice parameters and the compressibility of the sI hydrates agree with those from experimental measurements. The calculated bulk modulus for any mixture ratio of CH4 and CO2 hydrates varies between 8.5 GPa and 10.4 GPa at 271.15 K between 10 and 100 MPa. The calculated thermal expansion and specific heat capacities of CH4 hydrates are also comparable with experimental values above approximately 260 K. The compressibility and expansion coefficient of guest gas mixture hydrates increase with an increasing ratio of CO2-to-CH4, while the bulk modulus and specific heat capacity exhibit the opposite trend. The presented results for the specific heat capacities of 2220-2699.0 J kg(-1) K(-1) for any mixture ratio of CH4 and CO2 hydrates are the first reported so far. These computational results provide a useful database for practical natural gas recovery from CH4 hydrates in deep oceans where CO2 is considered to replace CH4, as well as for phase equilibrium and mechanical stability of gas hydrate-bearing sediments. The computational schemes also provide an appropriate balance between computational accuracy and cost for predicting

  10. 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

  11. 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.

    2015-01-01

    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

  12. Simulation of droplet transfer process and current waveform control of CO2 arc welding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A simulation system used in the arc welding short-circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical experiments. The simulation system can be used to simulate and test the current waveform control parameters with welding variables. By this simulation system, the influence regularities of the current waveform control parameters in the CO2 arc welding droplet short-circuit transfer process can be got. Moreover, the basic mode of real-time current waveform control can be also established by the simulation testing.

  13. Using Carbonyl Sulfide column measurements and a Chemical Transport Model to investigate variability in biospheric CO2 fluxes

    Science.gov (United States)

    Wang, Yuting; Petri, Christof; Palm, Mathias; Warneke, Thorsten; Baker, Ian; Berry, Joe; Suntharalingam, Parvadha; Campbell, Elliott; Wolf, Adam; Deutscher, Nick; Notholt, Justus

    2015-04-01

    Understanding the CO2 processes on land is of great importance, because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrieval of the atmospheric concentrations of both CO2 and OCS. Here, we investigate co-located and nearly simultaneous measurements of OCS and CO2 measured at 3 sites via FTIR spectrometers. These northern-hemispheric sites span a wide range of latitudes and all have multiple year time-series. The sites include Ny-Alesund (79°N), Bremen (53°N) and Paramaribo (6°N). We compare these measurements to simulations of OCS and CO2 using the GEOS-Chem model. The simulations are driven by different land biospheric fluxes of OCS and CO2 to match the seasonality of the measurements. The simple biosphere model (SiB-COS) are used in the study because it simultaneously calculates the biospheric fluxes of both OCS and CO2. The CO2 simulation with SiB fluxes agrees with the measurements better than a simulation using CASA. Comparison of the OCS simulations with different fluxes indicates that the latitudinal distribution of the OCS fluxes within SiB needs to be adjusted.

  14. 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

  15. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    Directory of Open Access Journals (Sweden)

    F. Delage

    2011-07-01

    Full Text Available Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2 emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel emission inventories with spatial and temporal differences over Europe and their impact on the model simulated CO2 concentration. Large temporal flux variations characterize the hourly fields (~40 % and ~80 % for the seasonal and diurnal cycles, peak-to-peak and annual country totals differ by 10 % on average and up to 40 % for some countries (i.e., the Netherlands. These emissions have been prescribed to seven different transport models, resulting in 28 different FFCO2 concentrations fields. The modeled FFCO2 concentration time series at surface sites using time-varying emissions show larger seasonal cycles (+2 ppm at the Hungarian tall tower (HUN and smaller diurnal cycles in summer (−1 ppm at HUN than when using constant emissions. The concentration range spanned by all simulations varies between stations, and is generally larger in winter (up to ~10 ppm peak-to-peak at HUN than in summer (~5 ppm. The contribution of transport model differences to the simulated concentration std-dev is 2–3 times larger than the contribution of emission differences only, at typical European sites used in global inversions. These contributions to the hourly (monthly std-dev's amount to ~1.2 (0.8 ppm and ~0.4 (0.3 ppm for transport and emissions, respectively. First comparisons of the modeled concentrations with 14C-based fossil fuel CO2 observations show that the large transport differences still hamper a quantitative evaluation/validation of the emission inventories. Changes in the estimated monthly biosphere flux (Fbio over Europe, using two inverse modeling approaches, are relatively small (less that 5 % while changes in annual Fbio (up to ~0.15 % GtC yr−1 are only

  16. Climate sensitivity due to increased CO2: experiments with a coupled atmosphere and ocean general circulation model

    Science.gov (United States)

    Washington, Warren M.; Meehl, Gerald A.

    1989-06-01

    A version of the National Center for Atmospheric Research community climate model — a global, spectral (R15) general circulation model — is coupled to a coarse-grid (5° latitude-] longitude, four-layer) ocean general circulation model to study the response of the climate system to increases of atmospheric carbon dioxide (CO2). Three simulations are run: one with an instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm), another with the CO2 concentration starting at 330 ppm and increasing linearly at a rate of 1% per year, and a third with CO2 held constant at 330 pm. Results at the end of 30 years of simulation indicate a globally averaged surface air temperature increase of 1.6° C for the instantaneous doubling case and 0.7°C for the transient forcing case. Inherent characteristics of the coarse-grid ocean model flow sea-surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes] produce lower sensitivity in this model after 30 years than in earlier simulations with the same atmosphere coupled to a 50-m, slab-ocean mixed layer. Within the limitations of the simulated meridional overturning, the thermohaline circulation weakens in the coupled model with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and westerly wind stress is decreased. In the transient forcing case with slowly increasing CO2 (30% increase after 30 years), the zonal mean warming of the ocean is most evident in the surface layer near 30° 50° S. Geographical plots of surface air temperature change in the transient case show patterns of regional climate anomalies that differ from those in the instantaneous CO2 doubling case, particularly in the North Atlantic and northern European regions. This suggests that differences in CO2 forcing in the climate system are important in CO2 response in regard to time-dependent climate anomaly regimes. This confirms earlier studies with simple climate models

  17. 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

  18. Why CO2 cools the middle atmosphere - a consolidating model perspective

    Science.gov (United States)

    Goessling, Helge F.; Bathiany, Sebastian

    2016-08-01

    Complex models of the atmosphere show that increased carbon dioxide (CO2) concentrations, while warming the surface and troposphere, lead to lower temperatures in the stratosphere and mesosphere. This cooling, which is often referred to as "stratospheric cooling", is evident also in observations and considered to be one of the fingerprints of anthropogenic global warming. Although the responsible mechanisms have been identified, they have mostly been discussed heuristically, incompletely, or in combination with other effects such as ozone depletion, leaving the subject prone to misconceptions. Here we use a one-dimensional window-grey radiation model of the atmosphere to illustrate the physical essence of the mechanisms by which CO2 cools the stratosphere and mesosphere: (i) the blocking effect, associated with a cooling due to the fact that CO2 absorbs radiation at wavelengths where the atmosphere is already relatively opaque, and (ii) the indirect solar effect, associated with a cooling in places where an additional (solar) heating term is present (which on Earth is particularly the case in the upper parts of the ozone layer). By contrast, in the grey model without solar heating within the atmosphere, the cooling aloft is only a transient blocking phenomenon that is completely compensated as the surface attains its warmer equilibrium. Moreover, we quantify the relative contribution of these effects by simulating the response to an abrupt increase in CO2 (and chlorofluorocarbon) concentrations with an atmospheric general circulation model. We find that the two permanent effects contribute roughly equally to the CO2-induced cooling, with the indirect solar effect dominating around the stratopause and the blocking effect dominating otherwise.

  19. Numerical modeling of CO2 mineralisation during storage in deep saline aquifers

    NARCIS (Netherlands)

    Ranganathan, P.; Van Hemert, P.; Rudolph, S.J.; Zitha, P.L.J.

    2011-01-01

    Simulations are performed to evaluate the feasibility of a potential site within the Rotliegend sandstone formation in the Dutch subsurface at a depth of around 3000 m for CO2 sequestration using the numerical simulator CMG-GEM. Three CO2 storage trapping mechanisms are studied: (1) mobility trappin

  20. Numerical modeling of CO2 mineralisation during storage in deep saline aquifers

    NARCIS (Netherlands)

    Ranganathan, P.; Van Hemert, P.; Rudolph, S.J.; Zitha, P.L.J.

    2011-01-01

    Simulations are performed to evaluate the feasibility of a potential site within the Rotliegend sandstone formation in the Dutch subsurface at a depth of around 3000 m for CO2 sequestration using the numerical simulator CMG-GEM. Three CO2 storage trapping mechanisms are studied: (1) mobility

  1. 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.

  2. ENHANCING THE ATOMIC-LEVEL UNDERSTANDING OF CO2 MINERAL SEQUESTRATION MECHANISMS VIA ADVANCED COMPUTATIONAL MODELING

    Energy Technology Data Exchange (ETDEWEB)

    A.V.G. Chizmeshya; M.J. McKelvy; G.H. Wolf; R.W. Carpenter; D.A. Gormley; J.R. Diefenbacher; R. Marzke

    2006-03-01

    have already significantly improved our understanding of mineral carbonation. Group members at the Albany Research Center have recently shown that carbonation of olivine and serpentine, which naturally occurs over geological time (i.e., 100,000s of years), can be accelerated to near completion in hours. Further process refinement will require a synergetic science/engineering approach that emphasizes simultaneous investigation of both thermodynamic processes and the detailed microscopic, atomic-level mechanisms that govern carbonation kinetics. Our previously funded Phase I Innovative Concepts project demonstrated the value of advanced quantum-mechanical modeling as a complementary tool in bridging important gaps in our understanding of the atomic/molecular structure and reaction mechanisms that govern CO2 mineral sequestration reaction processes for the model Mg-rich lamellar hydroxide feedstock material Mg(OH)2. In the present simulation project, improved techniques and more efficient computational schemes have allowed us to expand and augment these capabilities and explore more complex Mg-rich, lamellar hydroxide-based feedstock materials, including the serpentine-based minerals. These feedstock materials are being actively investigated due to their wide availability, and low-cost CO2 mineral sequestration potential. Cutting-edge first principles quantum chemical, computational solid-state and materials simulation methodology studies proposed herein, have been strategically integrated with our new DOE supported (ASU-Argonne National Laboratory) project to investigate the mechanisms that govern mineral feedstock heat-treatment and aqueous/fluid-phase serpentine mineral carbonation in situ. This unified, synergetic theoretical and experimental approach has provided a deeper understanding of the key reaction mechanisms than either individual approach can alone. We used ab initio techniques to significantly advance our understanding of atomic-level processes at the solid

  3. 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 th

  4. The seasonal cycle amplitude of total column CO2: factors behind the model-observation mismatch

    NARCIS (Netherlands)

    Basu, S.; Houweling, S.; Peters, W.; Sweeney, C.; Machida, T.; Maksyutov, S.; Patra, P. K.; Saito, R.; Chevallier, F.; Niwa, Y.; Matsueda, H.; Sawa, Y.

    2011-01-01

    CO2 surface fluxes that are statistically consistent with surface layer measurements of CO2, when propagated forward in time by atmospheric transport models, underestimate the seasonal cycle amplitude of total column CO2 in the northern temperate latitudes by 1–2 ppm. In this paper we verify the sys

  5. 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

  6. Modelling CO2 flow in naturally fractured geological media using MINC and multiple subregion upscaling procedure

    Science.gov (United States)

    Tatomir, Alexandru Bogdan A. C.; Flemisch, Bernd; Class, Holger; Helmig, Rainer; Sauter, Martin

    2017-04-01

    Geological storage of CO2 represents one viable solution to reduce greenhouse gas emission in the atmosphere. Potential leakage of CO2 storage can occur through networks of interconnected fractures. The geometrical complexity of these networks is often very high involving fractures occurring at various scales and having hierarchical structures. Such multiphase flow systems are usually hard to solve with a discrete fracture modelling (DFM) approach. Therefore, continuum fracture models assuming average properties are usually preferred. The multiple interacting continua (MINC) model is an extension of the classic double porosity model (Warren and Root, 1963) which accounts for the non-linear behaviour of the matrix-fracture interactions. For CO2 storage applications the transient representation of the inter-porosity two phase flow plays an important role. This study tests the accuracy and computational efficiency of the MINC method complemented with the multiple sub-region (MSR) upscaling procedure versus the DFM. The two phase flow MINC simulator is implemented in the free-open source numerical toolbox DuMux (www.dumux.org). The MSR (Gong et al., 2009) determines the inter-porosity terms by solving simplified local single-phase flow problems. The DFM is considered as the reference solution. The numerical examples consider a quasi-1D reservoir with a quadratic fracture system , a five-spot radial symmetric reservoir, and a completely random generated fracture system. Keywords: MINC, upscaling, two-phase flow, fractured porous media, discrete fracture model, continuum fracture model

  7. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries.

    Science.gov (United States)

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-09-15

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs.

  8. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries

    Science.gov (United States)

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-09-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs.

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

    Directory of Open Access Journals (Sweden)

    C. Heinze

    2011-10-01

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

  10. Sensitivity analysis of modelled responses of vegetation dynamics on the Tibetan Plateau to doubled CO2 and associated climate change

    Science.gov (United States)

    Qiu, Linjing; Liu, Xiaodong

    2016-04-01

    Increases in the atmospheric CO2 concentration affect both the global climate and plant metabolism, particularly for high-altitude ecosystems. Because of the limitations of field experiments, it is difficult to evaluate the responses of vegetation to CO2 increases and separate the effects of CO2 and associated climate change using direct observations at a regional scale. Here, we used the Community Earth System Model (CESM, version 1.0.4) to examine these effects. Initiated from bare ground, we simulated the vegetation composition and productivity under two CO2 concentrations (367 and 734 ppm) and associated climate conditions to separate the comparative contributions of doubled CO2 and CO2-induced climate change to the vegetation dynamics on the Tibetan Plateau (TP). The results revealed whether the individual effect of doubled CO2 and its induced climate change or their combined effects caused a decrease in the foliage projective cover (FPC) of C3 arctic grass on the TP. Both doubled CO2 and climate change had a positive effect on the FPC of the temperate and tropical tree plant functional types (PFTs) on the TP, but doubled CO2 led to FPC decreases of C4 grass and broadleaf deciduous shrubs, whereas the climate change resulted in FPC decrease in C3 non-arctic grass and boreal needleleaf evergreen trees. Although the combination of the doubled CO2 and associated climate change increased the area-averaged leaf area index (LAI), the effect of doubled CO2 on the LAI increase (95 %) was larger than the effect of CO2-induced climate change (5 %). Similarly, the simulated gross primary productivity (GPP) and net primary productivity (NPP) were primarily sensitive to the doubled CO2, compared with the CO2-induced climate change, which alone increased the regional GPP and NPP by 251.22 and 87.79 g C m-2 year-1, respectively. Regionally, the vegetation response was most noticeable in the south-eastern TP. Although both doubled CO2 and associated climate change had a

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

    Directory of Open Access Journals (Sweden)

    A. Granier

    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.

  12. 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.

  13. Temperature field modeling during multi-modes CO 2 laser irradiation of human enamel

    Science.gov (United States)

    Mihai, Oane; Scarlat, Florea; Mihailescu, Ion N.

    2007-04-01

    We examine the temperature fields of human enamel [Yu D, Fox JL, Hsu J, Lynn Powell G, Higuchi WI. Computer simulation of surface temperature profiles during CO 2 laser irradiation of human enamel. Opt Eng 1993; 32(2)] during multi-modes CO 2 laser irradiation. For this we use the integral transform method as well as direct and inverse Laplace transform [Oane M, Sporea D. Temperature profiles modeling in IR optical components during high power laser irradiation. Infrared Phys Technol 2001; 42(1): 31-40; Oane M, Sporea D. Study of heat transfer in IR optical components during CO 2 laser irradiation. Proc SPIE 2001; 4430: 898-904; Oane M. Mathematical modeling of the thermal field distributions in solids under multiple laser irradiations. Proc SPIE 2003; 5227: 329-34; Oane M, Apostol I, Timcu A. Temperature field modeling in laser heated metals for laser cleaning of surfaces. Proc SPIE 2003; 5227: 323-8]. The enamel block is modeled as homogeneous cylinder in three dimensions. Results indicate that (i) the thermal field depends on multi-modes structure; (ii) heat transfer coefficient plays an important role in temperature distribution.

  14. Sensitivity of interglacial Greenland temperature and δ18O: ice core data, orbital and increased CO2 climate simulations

    Directory of Open Access Journals (Sweden)

    D. Swingedouw

    2011-09-01

    Full Text Available The sensitivity of interglacial Greenland temperature to orbital and CO2 forcing is investigated using the NorthGRIP ice core data and coupled ocean-atmosphere IPSL-CM4 model simulations. These simulations were conducted in response to different interglacial orbital configurations, and to increased CO2 concentrations. These different forcings cause very distinct simulated seasonal and latitudinal temperature and water cycle changes, limiting the analogies between the last interglacial and future climate. However, the IPSL-CM4 model shows similar magnitudes of Arctic summer warming and climate feedbacks in response to 2 × CO2 and orbital forcing of the last interglacial period (126 000 years ago. The IPSL-CM4 model produces a remarkably linear relationship between TOA incoming summer solar radiation and simulated changes in summer and annual mean central Greenland temperature. This contrasts with the stable isotope record from the Greenland ice cores, showing a multi-millennial lagged response to summer insolation. During the early part of interglacials, the observed lags may be explained by ice sheet-ocean feedbacks linked with changes in ice sheet elevation and the impact of meltwater on ocean circulation, as investigated with sensitivity studies. A quantitative comparison between ice core data and climate simulations requires stability of the stable isotope – temperature relationship to be explored. Atmospheric simulations including water stable isotopes have been conducted with the LMDZiso model under different boundary conditions. This set of simulations allows calculation of a temporal Greenland isotope-temperature slope (0.3–0.4‰ per °C during warmer-than-present Arctic climates, in response to increased CO2, increased ocean temperature and orbital forcing. This temporal slope appears half as large as the modern spatial gradient and is consistent with other ice core estimates. It may, however, be model-dependent, as indicated by

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

    Science.gov (United States)

    Feng, Sha; Lauvaux, Thomas; Newman, Sally; Rao, Preeti; Ahmadov, Ravan; Deng, Aijun; Díaz-Isaac, Liza I.; Duren, Riley M.; Fischer, Marc L.; Gerbig, Christoph; Gurney, Kevin R.; Huang, Jianhua; Jeong, Seongeun; Li, Zhijin; Miller, Charles E.; O'Keeffe, Darragh; Patarasuk, Risa; Sander, Stanley P.; Song, Yang; Wong, Kam W.; Yung, Yuk L.

    2016-07-01

    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 individual measurement sites when a

  16. 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.

  17. 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

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

    Directory of Open Access Journals (Sweden)

    R. Arruda

    2015-05-01

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

  19. Physical Properties of CO2 Frost Formed by Radiative Cooling in a Mars Simulation Chamber

    Science.gov (United States)

    Wood, Stephen; Bruckner, A.; Hansen, G.; Cornwall, C.; Kimber, N.; Alvarez, F.

    2013-10-01

    We have performed realistic laboratory simulations of the thermal and radiative environment at the surface of Mars to produce the first samples of carbon dioxide ice formed as it does on Mars, by radiative cooling from a near-pure CO2 gas. It is important to determine the physical characteristics of Mars' seasonal CO2 polar ice caps because these determine their radiative properties which, in turn, control the polar energy balance and the seasonal variation in global surface pressure. It is not known whether they form as fluffy fine-grained deposits, dense solid ice, or something in between. Previous simulations have used conductive cooling, condensing CO2 onto a substrate cooled by liquid nitrogen (Kieffer 1968, Ditteon and Kieffer 1979). This technique favors the growth of grains having the best thermal contact with the surface, resulting in large grain sizes and a coarse texture. On Mars, however, the latent heat released by condensation must be lost radiatively to space. For this experiment, we have constructed a Mars simulation chamber containing low thermal conductivity analog regolith and low pressure CO2 gas. To grow radiation frost in the laboratory requires simultaneous containment of the atmosphere/vapor while allowing infrared radiation to escape (to balance the latent heat of condensation). Planets accomplish this using gravity to hold down the atmosphere. The key to our simulation is the use of a thin polypropylene film that is largely transparent in the thermal infrared yet strong enough to maintain the required pressure differential between our Mars-like "atmosphere" and the vacuum-enclosed space simulator (a liquid-nitrogen cooled plate). We use internal and external light sources to briefly illuminate the frost and obtain high resolution images of its physical morphology and texture using an in situ fiberscope with an articulated tip. Initial results will be presented.

  20. Simulation and energy performance assessment of CO2 removal from crude synthetic natural gas via physical absorption process

    Institute of Scientific and Technical Information of China (English)

    Wanjun Guo; Fei Feng; Guohui Song; Jun Xiao; Laihong Shen

    2012-01-01

    The paper presents an energy performance assessment of CO2 removal for crude synthetic natural gas (SNG) upgrade by Selexol absorption process.A simplified process simulation of the Selexol process concerning power requirement and separation performance was developed.The assessment indicates that less pressure difference between crude SNG and absorption pressure favors the energy performance of CO2 removal process.When both crude SNG and absorption pressures are 20 bar,CO2 removal process has the best energy performance.The optimal specific power consumption of the CO2 removal process is 566 kJ/kgCO2.The sensitivity analysis shows that the CO2 removal efficiency would significantly influence the total power consumption of the removal process,as well as higher heating value (HHV) and CO2 content in SNG.However,the specific power consumption excluding crude SNG and SNG compressions changes little with the variance of CO2 removal efficiency.If by-product CO2 is compressed for CO2 capture,the process would turn into a CO2-sink for the atmosphere.Correspondingly,an increase of 281 kJ/kgCO2 in specific power consumption is required for compressing the separated CO2.

  1. Evaluation of CO2-philicity of poly(vinyl acetate) and poly(vinyl acetate-alt-maleate) copolymers through molecular modeling and dissolution behavior measurement.

    Science.gov (United States)

    Hu, Dongdong; Sun, Shaojun; Yuan, Peiqing; Zhao, Ling; Liu, Tao

    2015-02-19

    Multiscale molecular modeling and dissolution behavior measurement were both used to evaluate the factors conclusive on the CO2-philicity of poly(vinyl acetate) (PVAc) homopolymer and poly(vinyl acetate-alt-maleate) copolymers. The ab initio calculated interaction energies of the candidate CO2-philic molecule models with CO2, including vinyl acetate dimer (VAc), dimethyl maleate (DMM), diethyl maleate (DEM), and dibutyl maleate (DBM), showed that VAc was the most CO2-philc segment. However, the cohesive energy density, solubility parameter, Flory-Huggins parameter, and radial distribution functions calculated by using the molecular dynamics simulations for the four polymer and polymer-CO2 systems indicated that poly(VAc-alt-DBM) had the most CO2-philicity. The corresponding polymers were synthesized by using free radical polymerization. The measurement of cloud point pressures of the four polymers in CO2 also demonstrated that poly(VAc-alt-DBM) had the most CO2-philicity. Although copolymerization of maleate, such as DEM or DBM, with PVAc reduced the polymer-CO2 interactions, the weakened polymer-polymer interaction increased the CO2-philicity of the copolymers. The polymer-polymer interaction had a significant influence on the CO2-philicity of the polymer. Reduction of the polymer-polymer interaction might be a promising strategy to prepare the high CO2-philic polymers on the premise that the strong polymer-CO2 interaction could be maintained.

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

    Science.gov (United States)

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

    2017-04-01

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

  3. Ionic Effects on Supercritical CO2-Brine Interfacial Tensions: Molecular Dynamics Simulations and a Universal Correlation with Ionic Strength, Temperature, and Pressure.

    Science.gov (United States)

    Zhao, Lingling; Ji, Jiayuan; Tao, Lu; Lin, Shangchao

    2016-09-13

    For geological CO2 storage in deep saline aquifers, the interfacial tension (IFT) between supercritical CO2 and brine is critical for the storage security and design of the storage capacitance. However, currently, no predictive model exists to determine the IFT of supercritical CO2 against complex electrolyte solutions involving various mixed salt species at different concentrations and compositions. In this paper, we use molecular dynamics (MD) simulations to investigate the effect of salt ions on the incremental IFT at the supercritical CO2-brine interface with respect to that at the reference supercritical CO2-water interface. Supercritical CO2-NaCl solution, CO2-CaCl2 solution and CO2-(NaCl+CaCl2) mixed solution systems are simulated at 343 K and 20 MPa under different salinities and salt compositions. We find that the valence of the cations is the primary contributor to the variation in IFT, while the Lennard-Jones potentials for the cations pose a smaller impact on the IFT. Interestingly, the incremental IFT exhibits a general linear correlation with the ionic strength in the above three electrolyte systems, and the slopes are almost identical and independent of the solution types. Based on this finding, a universal predictive formula for IFTs of CO2-complex electrolyte solution systems is established, as a function of ionic strength, temperature, and pressure. The predicted IFTs using the established formula agree perfectly (with a high statistical confidence level of ∼96%) with a wide range of experimental data for CO2 interfacing with different electrolyte solutions, such as those involving MgCl2 and Na2SO4. This work provides an efficient and accurate route to directly predict IFTs in supercritical CO2-complex electrolyte solution systems for practical engineering applications, such as geological CO2 sequestration in deep saline aquifers and other interfacial systems involving complex electrolyte solutions.

  4. 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 continent

  5. 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

  6. 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

    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 with the ......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...

  7. CO2捕集装置与机组集成模拟研究%Integration of CO2 capture device and power plant:numerical simulation

    Institute of Scientific and Technical Information of China (English)

    吕太; 马俊昆朋; 韩国夫; 刘练波; 牛红伟; 郜时旺

    2015-01-01

    At present,the maln CO2 capture technology for power plants is post combustion CO2 capture, which has advantages of low cost in reforming and high capture efficiency.Taking the HG-1793/26.15-YM1 boiler in an ultra supercritical 600 MW unit as an example,the Thermoflow software was adopted to carry out simulation investigation on the combustion system,steam water system and cooling system in de-tall,and the system integrated scheme was put forward.The results show that,with the CO2 capture effi-ciency of 90%,the integrated unit's net efficiency will decrease by 10.87%,the coal consumption will in-crease by 17.61%,the CO2 emission will reduce to 90.55 g/(kW•h)and the SOx emission will also drop from 0.042 2 g/(kW•h)to near-zero.%电厂CO2捕集技术主要以燃烧后 CO2捕集技术为主,其具有改造成本低、捕集效率高等特点.以超超临界600 MW 机组 HG-1793/26.15-YM1燃煤锅炉为例,利用 Thermoflow 软件,分别对燃烧系统、汽水系统、冷却系统进行模拟计算,提出了 CO2捕集装置与现役超临界机组的集成优选方案.结果表明:脱碳机组集成后,CO2捕集效率为90%时,集成机组净效率下降10.87%,燃煤量增加17.61%,CO2排放量降至90.55g/(kW•h),SOx 排放量由0.0422 g/(kW•h)降至接近0.

  8. Regional modelling of water and CO2-fluxes with a one-dimensional SVAT model

    Science.gov (United States)

    Kuhnert, M.; Köstner, B.

    2009-04-01

    Climate change affects site conditions for vegetation and may affect changes in the distribution of plant species. Investigations of these effects are difficult, because other influences on plant performance like land use and management also need to be considered. Carbon gain can be used as a sensitive indicator for changes in the vitality of the considered vegetation types that are affected by different climate and weather patterns. The objective of the presented study is the quantification of net photosynthesis rate, respiration and transpiration of different vegetation types on the regional scale. The study regions are the Weißeritz catchment in the Ore Mountains and the region Torgau-Oschatz in the Elbe basin both located in Saxony (East Germany) but significantly differing in elevation and site conditions. The carbon and water fluxes are simulated by an ecophysiological based Soil-Vegetation-Atmosphere-Transfer model for three periods (1996-2006, 2015-2025 and 2035-2045). The considered vegetation types are forest and grassland. The used model SVAT-CN is a multi-layer model, which enables the calculation of hourly carbon gain by coupling micrometerological data with ecophysiological processes. The calculations are based on the equations of Farquhar and Ball for net photosynthesis rate and stomata conductivity, respectively. It is a one-dimensional model which also considers soil water processes. The soil is coupled with the vegetation by one factor that depends on the matric potential and steers the calculation of the stomata conductivity. The equations of the soil water processes are based on a combination of bucket model and Richard's equation. Simulations are based on measured weather data (Dept. of Meteorology at Technische Universität Dresden and LfL Sachsen) with varying levels of atmospheric CO2 concentrations up to 580 ppm. Further, climate projections (ECHAM5-OM, IPCC emission scenario A1B), with downscaling to a 18x18km grid by the regional climate

  9. Molecular Dynamics Simulations of the Solubility of H2S and CO2 in Water

    OpenAIRE

    Roberto López Rendón; José Alejandre

    2008-01-01

    We have performed molecular dynamics simulations at constant temperature and pressure to calculate the solubility of carbon dioxide (CO2) and hydrogen sulfide (H2S) in water. The solubility of gases in water is important in several technological problems, in particular in the petroleum industry. The calculated liquid densities as function of temperature are in good agreement with experimental data. The results at the liquid-vapor equilibrium show that at low temperatures there is an important...

  10. Modelling distribution of evaporating CO2 in parallel minichannels

    DEFF Research Database (Denmark)

    Brix, Wiebke; Kærn, Martin Ryhl; Elmegaard, Brian

    2010-01-01

    -known empirical correlations for calculating frictional pressure drop and heat transfer coefficients. An investigation of different correlations for boiling two-phase flow shows that the choice of correlation is insignificant regarding the overall results. It is shown that non-uniform airflow leads...... to maldistribution of the refrigerant and considerable capacity reduction of the evaporator. Uneven inlet ualities to the different channels show only minor effects on the refrigerant distribution and evaporator capacity as long as the channels are vertically oriented with CO2 flowing upwards. For horizontal...

  11. 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...... properties. The approach combines the Henry's law constant and the chemical reaction equilibrium constant for the formation of carbamate for primary and secondary alkanolamines (MEA, DEA) or bicarbonate for tertiary alkanolamines(MDEA), resulting in an explicit expression for calculating the partial pressure...

  12. Simulating the dispersion of NOx and CO2 in the city of Zurich at building resolving scale

    Science.gov (United States)

    Brunner, Dominik; Berchet, Antoine; Emmenegger, Lukas; Henne, Stephan; Müller, Michael

    2017-04-01

    Cities are emission hotspots for both greenhouse gases and air pollutants. They contribute about 70% of global greenhouse gas emissions and are home to a growing number of people potentially suffering from poor air quality in the urban environment. High-resolution atmospheric transport modelling of greenhouse gases and air pollutants at the city scale has, therefore, several important applications such as air pollutant exposure assessment, air quality forecasting, or urban planning and management. When combined with observations, it also has the potential to quantify emissions and monitor their long-term trends, which is the main motivation for the deployment of urban greenhouse gas monitoring networks. We have developed a comprehensive atmospheric modeling model system for the city of Zurich, Switzerland ( 600,000 inhabitants including suburbs), which is composed of the mesoscale model GRAMM simulating the flow in a larger domain around Zurich at 100 m resolution, and the nested high-resolution model GRAL simulating the flow and air pollutant dispersion in the city at building resolving (5-10 m) scale. Based on an extremely detailed emission inventory provided by the municipality of Zurich, we have simulated two years of hourly NOx and CO2 concentration fields across the entire city. Here, we present a detailed evaluation of the simulations against a comprehensive network of continuous monitoring sites and passive samplers for NOx and analyze the sensitivity of the results to the temporal variability of the emissions. Furthermore, we present first simulations of CO2 and investigate the challenges associated with CO2 sources not covered by the inventory such as human respiration and exchange fluxes with urban vegetation.

  13. Effect of simulated tillage on microbial autotrophic CO2 fixation in paddy and upland soils.

    Science.gov (United States)

    Ge, Tida; Wu, Xiaohong; Liu, Qiong; Zhu, Zhenke; Yuan, Hongzhao; Wang, Wei; Whiteley, A S; Wu, Jinshui

    2016-01-22

    Tillage is a common agricultural practice affecting soil structure and biogeochemistry. To evaluate how tillage affects soil microbial CO2 fixation, we incubated and continuously labelled samples from two paddy soils and two upland soils subjected to simulated conventional tillage (CT) and no-tillage (NT) treatments. Results showed that CO2 fixation ((14)C-SOC) in CT soils was significantly higher than in NT soils. We also observed a significant, soil type- and depth-dependent effect of tillage on the incorporation rates of labelled C to the labile carbon pool. Concentrations of labelled C in the carbon pool significantly decreased with soil depth, irrespective of tillage. Additionally, quantitative PCR assays revealed that for most soils, total bacteria and cbbL-carrying bacteria were less abundant in CT versus NT treatments, and tended to decrease in abundance with increasing depth. However, specific CO2 fixation activity was significantly higher in CT than in NT soils, suggesting that the abundance of cbbL-containing bacteria may not always reflect their functional activity. This study highlights the positive effect of tillage on soil microbial CO2 fixation, and the results can be readily applied to the development of sustainable agricultural management.

  14. Exploration of CO2-Philicity of Poly(vinyl acetate-co-alkyl vinyl ether) through Molecular Modeling and Dissolution Behavior Measurement.

    Science.gov (United States)

    Hu, Dongdong; Sun, Shaojun; Yuan, Pei-Qing; Zhao, Ling; Liu, Tao

    2015-09-24

    Hydrocarbon CO2-philes are of great interest for use in expanding CO2 applications as a green solvent. In this work, multiscale molecular modeling and dissolution behavior measurement were both applied to explore CO2-philicity of the poly(vinyl acetate) (PVAc)-based copolymer. Introduction of a favorable comonomer, i.e., vinyl ethyl ether (VEE), could significantly reduce the polymer-polymer interaction on the premise that the polymer-CO2 interaction was not weakened but enhanced. The ab initio calculated interaction of the model molecules with CO2 demonstrated that the ether group in VEE or VBE was the suitable CO2-philic segment. From the molecular dynamics (MD) simulations of polymer/CO2 systems, the interaction energy and Flory-Huggins parameter (χ12) of poly(VAc-alt-VEE)/CO2 supported that poly(VAc-alt-VEE) possessed better CO2-philicity than PVAc. The dissolution behaviors of the synthesized poly(VAc-co-alkyl vinyl ether) copolymers in CO2 showed the best CO2-phile had the VEE content of about 34 mol %. The MD simulations also indicated that the interaction of random poly(VAc-co-VEE) containing about 30 mol % VEE with CO2 was the strongest and the χ12 was the smallest in these polymer/CO2 systems. Not only could the VEE monomer reduce the polymer-polymer interaction, but it could also enhance the polymer-CO2 interaction with an optimized composition. Introducing a suitable comonomer with a certain composition might be a promising strategy to form the synergistic effect of polymer-polymer interaction and polymer-CO2 interaction for screening the hydrocarbon CO2-philes.

  15. 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.

  16. Modeling greenhouse gas emissions (CO2, N2O, CH4) from managed arable soils with a fully coupled hydrology-biogeochemical modeling system simulating water and nutrient transport and associated carbon and nitrogen cycling at catchment scale

    Science.gov (United States)

    Klatt, Steffen; Haas, Edwin; Kraus, David; Kiese, Ralf; Butterbach-Bahl, Klaus; Kraft, Philipp; Plesca, Ina; Breuer, Lutz; Zhu, Bo; Zhou, Minghua; Zhang, Wei; Zheng, Xunhua; Wlotzka, Martin; Heuveline, Vincent

    2014-05-01

    The use of mineral nitrogen fertilizer sustains the global food production and therefore the livelihood of human kind. The rise in world population will put pressure on the global agricultural system to increase its productivity leading most likely to an intensification of mineral nitrogen fertilizer use. The fate of excess nitrogen and its distribution within landscapes is manifold. Process knowledge on the site scale has rapidly grown in recent years and models have been developed to simulate carbon and nitrogen cycling in managed ecosystems on the site scale. Despite first regional studies, the carbon and nitrogen cycling on the landscape or catchment scale is not fully understood. In this study we present a newly developed modelling approach by coupling the fully distributed hydrology model CMF (catchment modelling framework) to the process based regional ecosystem model LandscapeDNDC for the investigation of hydrological processes and carbon and nitrogen transport and cycling, with a focus on nutrient displacement and resulting greenhouse gas emissions in a small catchment at the Yanting Agro-ecological Experimental Station of Purple Soil, Sichuan province, China. The catchment hosts cypress forests on the outer regions, arable fields on the sloping croplands cultivated with wheat-maize rotations and paddy rice fields in the lowland. The catchment consists of 300 polygons vertically stratified into 10 soil layers. Ecosystem states (soil water content and nutrients) and fluxes (evapotranspiration) are exchanged between the models at high temporal scales (hourly to daily) forming a 3-dimensional model application. The water flux and nutrients transport in the soil is modelled using a 3D Richards/Darcy approach for subsurface fluxes with a kinematic wave approach for surface water runoff and the evapotranspiration is based on Penman-Monteith. Biogeochemical processes are modelled by LandscapeDNDC, including soil microclimate, plant growth and biomass allocation

  17. 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

  18. 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.

  19. Simulations of airglow variations induced by the CO2 increase and solar cycle variation from 1980 to 1991

    Science.gov (United States)

    Huang, Tai-Yin

    2016-09-01

    Airglow intensity and Volume Emission Rate (VER) variations induced by the increase of CO2 gas concentration and F10.7 variation (used as a proxy for the 11-year solar cycle variation) were investigated for the period from 1980 to 1991, encompassing a full solar cycle. Two airglow models are used to simulate the induced variations of O(1S) greenline, O2(0,1) atmospheric band , and OH(8,3) airglow for this study. The results show that both the airglow intensities and peak VERs correlate positively with the F10.7 solar cycle variation and display a small linear trend due to the increase of CO2 gas concentration. The solar-cycle induced airglow intensity variations show that O(1S) greenline has the largest variation (~26%) followed by the O2(0,1) atmospheric band (~23%) and then OH(8,3) airglow (~8%) over the 11 year timespan. The magnitudes of the induced airglow intensity variations by the increase of CO2 gas concentration are about an order of magnitude smaller than those by the F10.7 solar cycle variation. In general, the F10.7 solar cycle variation and CO2 increase do not seem to systematically alter the VER peak altitude of the airglow emissions, though the OH(8,3) VER peak altitude moves up slightly during the years when the F10.7 value falls under 100 SFU.

  20. Laboratory Simulation of CO2 Ice Condensation on Mars by Radiative Cooling

    Science.gov (United States)

    Wood, S. E.; Paige, D. A.; Smythe, W. D.

    1997-07-01

    We have performed realistic laboratory simulations of the thermal and radiative environment at the surface of Mars to produce the first samples of carbon dioxide ice formed as it does on Mars, by radiative cooling from a 600 Pa, near-pure CO2 gas. It is important to determine the physical characteristics of Mars' seasonal CO2 polar ice caps because these determine their radiative properties which, in turn, control the polar energy balance and the seasonal variation in global surface pressure. It is not known whether they form as fluffy fine-grained deposits, dense solid ice, or something in between. Previous simulations have used conductive cooling, condensing CO2 onto a substrate cooled by liquid nitrogen (Kieffer 1968, Ditteon and Kieffer 1979). This technique favors the growth of grains having the best thermal contact with the surface, resulting in large grain sizes and a coarse texture. On Mars, however, the latent heat released by condensation must be lost radiatively to space. To simulate this process in a lab it is necessary to separate the gas from the space simulator (a lN2-cooled black copper plate) using a material which is transparent at the appropriate thermal infrared wavelengths (> 10 /mu). For this experiment, we have constructed a Mars simulation chamber, an air-tight copper pot containing low thermal conductivity "soil" and CO2 gas, placed inside a thermal/vacuum chamber for insulation. To enable radiative cooling of the gas and "soil" inside the Mars chamber, its top is an infrared window; thin (12 /mum) polypropylene film. To be sure that the latent heat of condensation is not lost conductively to the chamber, the walls of the Mars chamber are maintained at a temperature just slightly higher than the condensation temperature. As the CO2 condenses, the pressure is maintained at 600 Pa automatically with a pressure control system. We will present measurements of the physical and radiative properties of the ice including; temperature, texture

  1. A Numerical Modeling Study of Effect of Heterogeneity on Capillary Trapping of Geologically Sequestrated CO2

    Science.gov (United States)

    Cihan, A.; Birkholzer, J. T.; Zhou, Q.; Trevisan, L.; Illangasekare, T. H.; Rodriguez, D.; Sakaki, T.

    2011-12-01

    Heterogeneities at multiple scales influence migration and trapping of geologically sequestrated CO2 during injection and post-injection periods. Understanding of small-scale processes is crucial to device upscaling methodologies for incorporating them into macroscopic-scale models. The upscaled models are in turn used to get insights into the complex field-scale processes involved in the migration of supercritical CO2. Theoretical research based on numerical model analysis presented in this study focuses on capillary entrapment in homogeneous and heterogeneous small-scale and intermediate-scale laboratory experiments with surrogate fluids, presented in a companion presentation (Treviso et al., 2011). An improved understanding of pore-scale and larger scale processes on capillary entrapment may be achieved by combining pore-scale and macroscopic-scale modeling approaches. Capillarity controlled entrapped non-wetting phase saturation in macroscopic-scale models is generally either provided as an input parameter after laboratory scale measurements or estimated empirically. A particle trajectory modeling approach with pore-scale physics included is used to gain insights to development of physically-based models for the capillary entrapment in homogeneous and heterogeneous systems. The particle trajectory modeling generates functional relationships between phase saturation, entrapped phase saturation, hydraulic properties of the medium, and velocity of injected phase, which eventually are planned to be used for developing macroscopic scale models of capillary entrapment. The predictions of entrapped fluid saturation from the particle trajectory model are verified with measurements from the small scale experimental test systems. Macroscopic two-phase flow modeling approach with existing and modified constitutive models is tested by comparisons with both small-scale and intermediate-scale experimental results. T2VOC module based on TOUGH2 is used to simulate two

  2. Amine modeling for CO2 capture: internals selection.

    Science.gov (United States)

    Karpe, Prakash; Aichele, Clint P

    2013-04-16

    Traditionally, trays have been the mass-transfer device of choice in amine absorption units. However, the need to process large volumes of flue gas to capture CO2 and the resultant high costs of multiple trains of large trayed columns have prompted process licensors and vendors to investigate alternative mass-transfer devices. These alternatives include third-generation random packings and structured packings. Nevertheless, clear-cut guidelines for selection of packings for amine units are lacking. This paper provides well-defined guidelines and a consistent framework for the choice of mass-transfer devices for amine absorbers and regenerators. This work emphasizes the role played by the flow parameter, a measure of column liquid loading and pressure, in the type of packing selected. In addition, this paper demonstrates the significant economic advantage of packings over trays in terms of capital costs (CAPEX) and operating costs (OPEX).

  3. 大气CO2浓度非均匀动态分布条件下的气候模拟%Climate simulation for dynamic heterogeneous distribution of atmospheric CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    杨成荫; 王汉杰; 韩士杰; 赵苏璇

    2012-01-01

    from March 2000 to February 2009 are simulated and the model outputs data are analyzed by comparison method. The possible mechanism that the dynamic heterogeneous CO2 distribution causes different regional climate change is also studied. The simulation study shows that the greenhouse effect of CO2 might have been aggrandized about 10% in the tranditional climate simulation due to the improper assumption of stable and homogenous atmospheric CO2 concentration. Then the paper analyzes the possible mechanism of greenhouse effect reduction induced by the dynamic heterogeneous CO2 concentration distribution. The analysis indicates that the greenhouse effect by CO2 itself (always referred as changing atmospheric transmittivity) is not the main reason to deduct temperature in the Exp2. The variety of atmospheric CO2 concentration influences on the CO2 partial pressure between atomosphere and internal plant cell first, and then the land plants adjust to this change by altering their stomatal conductance, which affects the water evapotranspiration from plant leaf to atmosphere consequently. On the one hand, these effects affect environmental temperature through the evaporation cooling, on the other hand, the evaporated moisture alter the air humidity and influence the formation and amount of low cloud. In winter, most plants are under dormancy season, there are little response to the change of atmospheric CO2 concentration, and then the change of the humidity and low cloud is unconspicuous. In summer, the most plants are under the vigorous growing period and there are more active biological actions that tranfer more water vapor into the atmosphere and then more cloud formatted due to this CO2 physiological forcing effect. The increased low cloud resist the solar shortwave radiation from reaching the lower part of the atmosphere and cause temperature reduction, on the other hand, the radiative cooling effect from the top of the cloud can also cause lower temperature in the

  4. Simulating the integrated summertime Δ14CO2 signature from anthropogenic emissions over Western Europe

    NARCIS (Netherlands)

    Bozhinova, D.; van der Molen, M. K.; van der Velde, I. R.; Krol, M. C.; van der Laan, S.; Meijer, H. A. J.; Peters, W.

    2014-01-01

    Radiocarbon dioxide (14CO2, reported in Δ14CO2) can be used to determine the fossil fuel CO2 addition to the atmosphere, since fossil fuel CO2 no longer contains any 14C. After the release of CO2 at the source, atmospheric transport causes dilution of strong local signals into the background and det

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

    Science.gov (United States)

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

    2016-12-01

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

  6. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

  8. Quantification and modelling of on-road CO2 emissions and its impacts on ambient CO2 concentrations in an Indian coastal city

    Science.gov (United States)

    Madhipatla, K. K.

    2015-12-01

    This paper presents the results of CO2 emission inventory, monitoring of CO2 concentrations and modelling of on road CO2 emissions in an Indian coastal city. Bottom up approach was adopted for quantifying the grid wise on road CO2 emissions of Chennai city at a finer resolution of 1Km x 1Km using the real time traffic data of 56 major roads. In addition, monitoring of ground level CO2 concentrations and vehicular traffic were carried out at a residential site in Chennai to understand the impact of vehicular emissions on the ambient CO2 levels. Further, AERMOD, a US EPA regulatory model, was deployed to find the spatial variation of CO2 concentrations due to the emissions from 38 major corridors of Chennai. Results indicated that a total emission of 0.65 Tg/year of CO2 was emitted by the vehicular traffic from the major roads of Chennai. Cars were identified as the larger emitters of CO2 with a contribution of 25% of the total emissions followed by three wheelers (21%), trucks (16%), buses (15%), two wheelers (13%) and Light Commercial Vehicles (9%). Ground level CO2 concentrations at the study area were in the range 391.52 to 666.37 ppm, with a mean hourly concentration of 448 ± 33.45 ppm. It was observed that the CO2 concentrations were high during the morning and evening peak hours and low during the afternoons and further vehicular emissions were found to have a significant effect on the ambient CO2 concentrations during the morning peak hours (R2=0.78) and afternoons (R2=0.50). But, contrastingly, a weak correlation was observed between the vehicular emissions and CO2 concentrations during the evening peak hours (R2=0.02). In addition, night time CO2 concentrations were observed higher in the weekends corresponding to high vehicular traffic during the late evenings. From the modelling results, it was found that the considered 38 major corridors contribute 0.12 ppm of CO2 per year to the ambient atmosphere.

  9. Growing wheat in Biosphere 2 under elevated CO2: observations and modeling

    Science.gov (United States)

    Tubiello, F. N.; Mahato, T.; Morton, T.; Druitt, J. W.; Volk, T.; Marino, B. D.

    1999-01-01

    Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.

  10. Response of the Atlantic Thermohaline Circulation to Increased Atmospheric CO2 in a Coupled Model.

    Science.gov (United States)

    Hu, Aixue; Meehl, Gerald A.; Washington, Warren M.; Dai, Aiguo

    2004-11-01

    Changes in the thermohaline circulation (THC) due to increased CO2 are important in future climate regimes. Using a coupled climate model, the Parallel Climate Model (PCM), regional responses of the THC in the North Atlantic to increased CO2 and the underlying physical processes are studied here. The Atlantic THC shows a 20-yr cycle in the control run, qualitatively agreeing with other modeling results. Compared with the control run, the simulated maximum of the Atlantic THC weakens by about 5 Sv (1 Sv 106 m3 s-1) or 14% in an ensemble of transient experiments with a 1% CO2 increase per year at the time of CO2 doubling. The weakening of the THC is accompanied by reduced poleward heat transport in the midlatitude North Atlantic. Analyses show that oceanic deep convective activity strengthens significantly in the Greenland Iceland Norway (GIN) Seas owing to a saltier (denser) upper ocean, but weakens in the Labrador Sea due to a fresher (lighter) upper ocean and in the south of the Denmark Strait region (SDSR) because of surface warming. The saltiness of the GIN Seas are mainly caused by an increased salty North Atlantic inflow, and reduced sea ice volume fluxes from the Arctic into this region. The warmer SDSR is induced by a reduced heat loss to the atmosphere, and a reduced sea ice flux into this region, resulting in less heat being used to melt ice. Thus, sea ice related salinity effects appear to be more important in the GIN Seas, but sea ice melt-related thermal effects seem to be more important in the SDSR region. On the other hand, the fresher Labrador Sea is mainly attributed to increased precipitation. These regional changes produce the overall weakening of the THC in the Labrador Sea and SDSR, and more vigorous ocean overturning in the GIN Seas. The northward heat transport south of 60°N is reduced with increased CO2, but increased north of 60°N due to the increased flow of North Atlantic water across this latitude.

  11. 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 surroundi

  12. Simple dielectric mixing model in the monitoring of CO2 leakage from geological storage aquifer

    Science.gov (United States)

    Abidoye, L. K.; Bello, A. A.

    2017-01-01

    The principle of the dielectric mixing for multiphase systems in porous media has been employed to investigate CO2-water-porous media system and monitor the leakage of CO2, in analogy to scenarios that can be encountered in geological carbon sequestration. A dielectric mixing model was used to relate the relative permittivity for different subsurface materials connected with the geological carbon sequestration. The model was used to assess CO2 leakage and its upward migration, under the influences of the depth-dependent characteristics of the subsurface media as well as the fault-connected aquifers. The results showed that for the upward migration of CO2 in the subsurface, the change in the bulk relative permittivity (εb) of the CO2-water-porous media system clearly depicts the leakage and movement of CO2, especially at depth shallower than 800 m. At higher depth, with higher pressure and temperature, the relative permittivity of CO2 increases with pressure, while that of water decreases with temperature. These characteristics of water and supercritical CO2, combine to limit the change in the εb, at higher depth. Furthermore, it was noticed that if the pore water was not displaced by the migrating CO2, the presence of CO2 in the system increases the εb. But, with the displacement of pore water by the migrating CO2, it was shown how the εb profile decreases with time. Owing to its relative simplicity, composite dielectric behaviour of multiphase materials can be effectively deployed for monitoring and enhancement of control of CO2 movement in the geological carbon sequestration.

  13. Simulation of Binary CO2/CH4 Mixture Breakthrough Profiles in MIL-53 (Al

    Directory of Open Access Journals (Sweden)

    Luis Fernando Gomez

    2015-01-01

    Full Text Available MIL-53 (Al aluminum terephthalate, a commercial metal-organic framework, has been studied as a potential candidate for pressure swing adsorption separation of CO2/CH4 binary mixtures. Pure gas isotherms of CH4 and CO2 measured over 0–6 MPa and at room temperature are fitted with the Dubinin-Astakhov (D-A model. The D-A model parameters are used in the Doong-Yang Multicomponent adsorption model to predict the binary mixture isotherms. A one-dimensional multicomponent adsorption breakthrough model is then used to perform a parametric study of the effect of adsorbent particle diameter, inlet pressures, feed flow rates, and feed compositions on the breakthrough performance. Commercial MIL-53 with a particle diameter of 20 μm renders high tortuous flow; therefore it is less effective for separation. More effective separation can be achieved if MIL-53 monoliths of diameters above 200 μm are used. Faster separation is possible by increasing the feed pressure or if the starting compositions are richer in CO2. More CH4 is produced per cycle at higher feed pressures, but the shortened time at higher pressures can result in the reduction of the CH4 purity.

  14. West African monsoon dynamics and precipitation: the competition between global SST warming and CO2 increase in CMIP5 idealized simulations

    Science.gov (United States)

    Gaetani, Marco; Flamant, Cyrille; Bastin, Sophie; Janicot, Serge; Lavaysse, Christophe; Hourdin, Frederic; Braconnot, Pascale; Bony, Sandrine

    2016-04-01

    Climate variability associated with the West African monsoon (WAM) has important environmental and socio-economic impacts in the region. However, state-of-the-art climate models still struggle in producing reliable climate predictions. An important cause of this low predictive skill is the sensitivity of climate models to different forcings. In this study, the mechanisms linking the WAM dynamics to the CO2 forcing are investigated, by comparing the effect of the CO2 direct radiative effect with its indirect effect mediated by the global sea surface warming. The July-to-September WAM variability is studied in climate simulations extracted from the Coupled Model Intercomparison Project Phase 5 archive, driven by prescribed sea surface temperature (SST). The individual roles of global SST warming and CO2 atmospheric concentration increase are investigated through idealized experiments simulating a 4 K warmer SST and a quadrupled CO2 concentration, respectively. Results show opposite and competing responses in the WAM dynamics and precipitation. A dry response (-0.6 mm/day) to the SST warming is simulated in the Sahel, with dryer conditions over western Sahel (-0.8 mm/day). Conversely, the CO2 increase produces wet conditions (+0.5 mm/day) in the Sahel, with the strongest response over central-eastern Sahel (+0.7 mm/day). The associated responses in the atmospheric dynamics are also analysed, showing that the SST warming affects the Sahelian precipitation through modifications in the global tropical atmospheric dynamics, reducing the importance of the regional drivers, while the CO2 increase reinforces the coupling between precipitation and regional dynamics. A general agreement in model responses demonstrates the robustness of the identified mechanisms linking the WAM dynamics to the CO2 direct and indirect forcing, and indicates that these primary mechanisms are captured by climate models. Results also suggest that the spread in future projections may be caused by

  15. West African monsoon dynamics and precipitation: the competition between global SST warming and CO2 increase in CMIP5 idealized simulations

    Science.gov (United States)

    Gaetani, Marco; Flamant, Cyrille; Bastin, Sophie; Janicot, Serge; Lavaysse, Christophe; Hourdin, Frederic; Braconnot, Pascale; Bony, Sandrine

    2017-02-01

    Climate variability associated with the West African monsoon (WAM) has important environmental and socio-economic impacts in the region. However, state-of-the-art climate models still struggle in producing reliable climate predictions. An important cause of this low predictive skill is the sensitivity of climate models to different forcings. In this study, the mechanisms linking the WAM dynamics to the CO2 forcing are investigated, by comparing the effect of the CO2 direct radiative effect with its indirect effect mediated by the global sea surface warming. The July-to-September WAM variability is studied in climate simulations extracted from the Coupled Model Intercomparison Project Phase 5 archive, driven by prescribed sea surface temperature (SST). The individual roles of global SST warming and CO2 atmospheric concentration increase are investigated through idealized experiments simulating a 4 K warmer SST and a quadrupled CO2 concentration, respectively. Results show opposite and competing responses in the WAM dynamics and precipitation. A dry response (-0.6 mm/day) to the SST warming is simulated in the Sahel, with dryer conditions over western Sahel (-0.8 mm/day). Conversely, the CO2 increase produces wet conditions (+0.5 mm/day) in the Sahel, with the strongest response over central-eastern Sahel (+0.7 mm/day). The associated responses in the atmospheric dynamics are also analysed, showing that the SST warming affects the Sahelian precipitation through modifications in the global tropical atmospheric dynamics, reducing the importance of the regional drivers, while the CO2 increase reinforces the coupling between precipitation and regional dynamics. A general agreement in model responses demonstrates the robustness of the identified mechanisms linking the WAM dynamics to the CO2 direct and indirect forcing, and indicates that these primary mechanisms are captured by climate models. Results also suggest that the spread in future projections may be caused by

  16. 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

  17. 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

  18. A general model for CO2 regulation: the case of Denmark

    DEFF Research Database (Denmark)

    Svendsen, Gert Tinggaard

    1998-01-01

    for the public electricity sector. Permits are then to be devaluated in year 2005 by 20%. A CO2 tax should be correctly set at a $50 level in year 2005 for households, transportation sector and private firms not participating in the CO2 market. This model may guide future energy policies in other countries...

  19. Mathematical modelling of gain-switched RF-excited CO2 waveguide laser

    Institute of Scientific and Technical Information of China (English)

    Hussain Badran; Tian Zhao-Shuo; Wang Qi

    2004-01-01

    The detailed mathematical models for the evolution of light pulses in RF-excited CO2 waveguide lasers are derived.Explicit expressions for the pulse characteristics in RF-excited CO2 waveguide lasers are obtained. The effects of losses and unsaturated gain on output power are calculated.

  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. Simulation and experimental validation of a 400 m vertical CO2 heat pipe for geothermal application

    Science.gov (United States)

    Ebeling, Johann-Christoph; Kabelac, Stephan; Luckmann, Sebastian; Kruse, Horst

    2017-03-01

    Geothermal heat pipes are an effective heat source for heat pumps used for space heating. Because the area for the installation of borehole heat exchangers is limited in urban areas (one site per borehole), the maximum heat extractable from one borehole shall rise. In cooperation with the FKW Hannover, the Institute for Thermodynamics of the Leibniz University of Hannover is investigating the thermodynamic behavior of CO2 driven geothermal heat pipes of higher thermal power. Therefore two different types of geothermal heat pipes with a length of 400 m each have been installed. Furthermore a numerical simulation of the heat and mass transfer within the pipes is under development. The experimental setup and first results of the experiments are presented as well as the current status of the numerical simulation. A comparison of the two different types of heat pipes and a comparison of the experimental data with the numerical simulation is given.

  2. Environmental dependencies of plant CO2 uptake in theory, data, and simulations

    Science.gov (United States)

    Wang, Han; Prentice, Colin; Keenan, Trevor; Peng, Shushi; Piao, Shilong; Cornwell, William; Davis, Tyler; Wright, Ian; Peng, Changhui

    2016-04-01

    The rate of carbon uptake by land plants depends on the light use efficiency (LUE) of photosynthesis. LUE is the ratio of primary production to light absorbed by foliage. This in turn depends on the ratio of leaf-internal to ambient carbon dioxide partial pressures (χ). However, current state-of-the-art land ecosystem models represent the environmental dependencies of these two key quantities in an empirical and incomplete way. Their modeled values have not been systematically tested against observations, a situation contributing to the many uncertainties afflicting current model estimates and future projections of terrestrial carbon uptake. We present a theory for the dependencies of χ and LUE on growing-season air temperature, vapour pressure deficit (VPD), CO2 concentration and elevation based on two hypotheses rooted in eco-physiological optimality. Theoretically derived environmental dependencies of χ and LUE are shown to be precisely and quantitatively consistent with global data sets of (a) stable carbon isotope measurements, and (b) gross primary production derived from CO2 flux measurements. The modeled environmental dependencies of χ and LUE according to seven state-of-the-art land ecosystem models participating in the TRENDY2 model intercomparison project are then derived from model outputs and compared with the theoretical relationships as a benchmark. The results show large discrepancies among model-predicted relationships of χ and LUE to temperature and VPD both in spatial and temporal dimensions. The influence of elevation on χ and LUE is also inconsistent among models, as is their predicted sensitivity to CO2 enrichment. This work suggests that a top-priority task for land ecosystem models should be to reformulate the environmental drivers of χ and LUE relationships to be consistent with observations. It also indicates that eco-physiological optimality hypotheses provide a promising route to an improved predictive understanding of terrestrial

  3. Pore scale modeling of reactive transport involved in geologic CO2 sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Qinjin [Los Alamos National Laboratory; Lichtner, Peter C [Los Alamos National Laboratory; Viswanathan, Hari S [Los Alamos National Laboratory; Abdel-fattah, Amr I [Los Alamos National Laboratory

    2009-01-01

    We apply a multi-component reactive transport lattice Boltzmann model developed in previolls studies to modeling the injection of a C02 saturated brine into various porous media structures at temperature T=25 and 80 C. The porous media are originally consisted of calcite. A chemical system consisting of Na+, Ca2+, Mg2+, H+, CO2(aq), and CI-is considered. The fluid flow, advection and diHusion of aqueous species, homogeneous reactions occurring in the bulk fluid, as weB as the dissolution of calcite and precipitation of dolomite are simulated at the pore scale. The effects of porous media structure on reactive transport are investigated. The results are compared with continuum scale modeling and the agreement and discrepancy are discussed. This work may shed some light on the fundamental physics occurring at the pore scale for reactive transport involved in geologic C02 sequestration.

  4. Seismicity induced by CO2 injection: lesson learned from coupled hydro-mechanical modeling

    Science.gov (United States)

    Rinaldi, Antonio Pio; Rutqvist, Jonny; Urpi, Luca; Cappa, Frederic; Jeanne, Pierre; Vilarrasa, Victor

    2017-04-01

    Overpressure caused by the direct injection of CO2 into a deep sedimentary system may produce changes in the state of stress, as well as, have an impact on the sealing capabilities of the targeted system. The importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestration operations has recently become more widely recognized. In this context, here we review and summarize some recent modeling efforts, aimed at understanding the possible seismicity induced by CO2 storage and its relation to potential leakage to shallow groundwater aquifer during active injection. The simulations were conducted using TOUGH-FLAC, a simulator for coupled multiphase flow and geomechanical modeling. We carried out both quasi-static and dynamic simulations, with an explicit representation of a fault. In the case of quasi-static modeling, a strain softening Mohr-Coulomb model was used to model a slip-weakening fault slip behavior, enabling modeling of sudden slip that was interpreted as a seismic event, with a moment magnitude evaluated using formulas from seismology. In the case of dynamic modeling, we simulate the fault behavior as strain-softening or rate-dependent, analyzing the frequency behavior at surface and the possible effects of friction properties on slip. This work aims at studying the fault responses during carbon dioxide injection, focusing on the short-term (5 years) integrity of the storage repository, and hence, on the potential leakage towards shallow groundwater aquifers. We account for stress/strain-dependent permeability and study both the fault reactivation and the leakage through the fault zone. We analyze several scenarios related to the injected amount of CO2 (and hence related to potential overpressure) involving both minor and major faults, and study induced seismicity and leakage for different stress/strain permeability coupling functions, as well as increasing the complexity of the system in

  5. 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

  6. European source and sink areas of CO2 retrieved from Lagrangian transport model interpretation of combined O2 and CO2 measurements at the high alpine research station Jungfraujoch

    Directory of Open Access Journals (Sweden)

    D. Brunner

    2011-08-01

    Full Text Available The University of Bern monitors carbon dioxide (CO2 and oxygen (O2 at the High Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and since 2005 using a continuous in situ measurement system. This study investigates the transport of CO2 and O2 towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM simulations and utilizes CO2 and O2 signatures to classify air masses. By investigating the simulated transport patterns associated with distinct CO2 concentrations it is possible to decipher different source and sink areas over Europe. The highest CO2 concentrations, for example, were observed in winter during pollution episodes when air was transported from Northeastern Europe towards the Alps, or during south Foehn events with rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies. To study the importance of air-sea exchange for variations in O2 concentrations at Jungfraujoch the correlation between CO2 and APO (Atmospheric Potential Oxygen deviations from a seasonally varying background was analyzed. Anomalously high APO concentrations were clearly associated with air masses originating from the Atlantic Ocean, whereas low APO concentrations were found in air masses advected either from the east from the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air masses with low APO in summer were also strongly depleted in CO2 suggesting a combination of CO2 uptake by vegetation and O2 uptake by dry summer soils. Other subsets of points in the APO-CO2 scatter plot investigated with respect to air mass origin included CO2 and APO background values and points with regular APO but anomalous CO2 concentrations. Background values were associated with free tropospheric air masses with little contact with the boundary layer during the last few days, while high or low CO2 concentrations reflect the various levels of influence of anthropogenic

  7. CO2 Absorption in a Lab-Scale Fixed Solid Bed Reactor: Modelling and Experimental Tests

    Directory of Open Access Journals (Sweden)

    Roberto Gabbrielli

    2004-09-01

    Full Text Available The CO2 absorption in a lab-scale fixed solid bed reactor filled with different solid sorbents has been studied under different operative conditions regarding temperature (20-200°C and input gas composition (N2, O2, CO2, H2O at 1bar pressure. The gas leaving the reactor has been analysed to measure the CO2 and O2 concentrations and, consequently, to evaluate the overall CO2 removal efficiency. In order to study the influence of solid sorbent type (i.e. CaO, coal bottom ash, limestone and blast furnace slag and of mass and heat transfer processes on CO2 removal efficiency, a one-dimensional time dependent mathematical model of the reactor, which may be considered a Plug Flow Reactor, has been developed. The quality of the model has been confirmed using the experimental results.

  8. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    NARCIS (Netherlands)

    Peylin, P.; Houweling, S.; Krol, M.C.|info:eu-repo/dai/nl/078760410; Karstens, U.; Pieterse, G.|info:eu-repo/dai/nl/304840858; Ciais, P.; Heimann, M.

    2011-01-01

    Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2) emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel

  9. Predictive Model for Corrosion Rate of Oil Tubes in CO2/H2 S Coexistent Environment Part Ⅰ :Building of Model

    Institute of Scientific and Technical Information of China (English)

    李全安; 白真权; 黄得志; 张清; 文九巴; 李鹤林

    2004-01-01

    Based on an analysis of the existing models of CO2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (rcorr) in CO2/H2 S corrosion for oil tubes has been established, in which rcorr is expressed as a function of pH, temperature ( T), pressure of CO2 ( Pco2 ) and pressure of H2S ( PH2S ). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: ( 1 ) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the rcorr in CO2/H2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2)The linear relationship still exists between In rcorr and In Pco2 in CO2/H2S corrosion (as same as that in CO2 corrosion). Therefore,a correction factor as a function of PH2S has been introduced into the predictive model in CO2/H2S corrosion. (3) The model is compatible with the main existing models.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. NETL to establish Dynamic Simulation Research and Training Center to promote IGCC technology with CO2 cpture

    Energy Technology Data Exchange (ETDEWEB)

    Provost, G.; Zitney, S.; Turton, R.; Erbes, M.; Stone, H.; Bhattacharyya, D.; Liese, E.; McClintock, M.; Quintrell, M.

    2009-01-01

    To meet increasing demand for education and experience with commercial-scale, coal-fired, integrated gasification combined cycle (IGCC) plants with CO2 capture, the Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) is leading a project to deploy a generic, full-scope, real-time IGCC dynamic plant simulator for use in establishing a world-class research and training center, and to promote and demonstrate IGCC technology to power industry personnel. The simulator, being built by Invensys Process Systems (IPS), will be installed at two separate sites, at NETL and West Virginia University (WVU), and will combine a process/gasification simulator with a power/combined-cycle simulator together in a single dynamic simulation framework for use in engineering research studies and training applications. The simulator, scheduled to be launched in mid-year 2010, will have the following capabilities: High-fidelity, dynamic model of process-side (gasification and gas cleaning with CO2 capture) and power-block-side (combined cycle) for a generic IGCC plant fueled by coal and/or petroleum coke. Highly flexible configuration that allows concurrent training on separate gasification and combined cycle simulators, or up to two IGCC simulators. Ability to enhance and modify the plant model to facilitate studies of changes in plant configuration, equipment, and control strategies to support future R&D efforts. Training capabilities including startup, shutdown, load following and shedding, response to fuel and ambient condition variations, control strategy analysis (turbine vs. gasifier lead, etc.), representative malfunctions/trips, alarms, scenarios, trending, snapshots, data historian, etc. To support this effort, process descriptions and control strategies were developed for key sections of the plant as part of the detailed functional specification, which is serving as the basis of the simulator development. In this paper, we highlight the contents of the

  15. Numerical Simulation Study on the Impacts of Tropospheric O3 and CO2 Concentration Changes on Winter Wheat. Part Ⅱ:Simulation Results and Analyses

    Institute of Scientific and Technical Information of China (English)

    ZHENG Changling; WANG Chunyi

    2006-01-01

    With the rapid development of industrialization and urbanization, the enrichment of tropospheric ozone and carbon dioxide concentration at striking rates has caused effects on biosphere, especially on crops. It is generally accepted that the increase of CO2 concentration will have obverse effects on plant productivity while ozone is reported as the air pollutant most damaging to agricultural crops and other plants. The Model of Carbon and Nitrogen Biogeochemistry in Agroecosystems (DNDC) was adapted to evaluate simultaneously impacts of climate change on winter wheat.Growth development and yield formation of winter wheat under different Os and CO2 concentration conditions are simulated with the improved DNDC model whose structure has been described in another paper. Through adjusting the DNDC model applicability, winter wheat growth and development in Gucheng Station were simulated well in 1993 and 1999, which is in favor of modifying the model further. The model was validated against experiment observation, including development stage data, leaf area index, each organ biomass, and total aboveground biomass. Sensitivity tests demonstrated that the simulated results in development stage and biomass were sensitive to temperature change. The main conclusions of the paper are the following: 1) The growth and yield of winter wheat under CO2 concentration of 500 ppmv, 700 ppmv and the current ozone concentration are simulated respectively by the model. The results are well fitted with the observed data of OTCs experiments. The results show that increase of CO2 concentration may improve the growth of winter wheat and elevate the yield. 2) The growth and yield of winter wheat under O3 concentration of 50 ppbv, 100 ppbv, 200 ppbv and the based concentration CO2 are simulated respectively by the model. The simulated curves of stem, leaf, and spike organs growth as well as leaf area index are well accounted with the observed data. The results reveal that ozone has negative

  16. Multicomponent CO2-Brine Simulations of Fluid and Heat Transfer in Sedimentary-Basin Geothermal Systems: Expanding Geothermal Energy Opportunities

    Science.gov (United States)

    Saar, M. O.; Randolph, J. B.

    2011-12-01

    In a carbon dioxide plume geothermal (CPG) system, carbon dioxide (CO2) is pumped into existing high-permeability geologic formations that are overlain by a low-permeability caprock. The resulting CO2 plume largely displaces native formation fluid and is heated by the natural in-situ heat and background geothermal heat flux. A portion of the heated CO2 is piped to the surface to produce power and/or to provide heat for direct use before being returned to the geologic reservoir. Non-recoverable CO2 in the subsurface is geologically sequestered, serving as a CO2 sink. As such, this approach results in a geothermal power plant with a negative carbon footprint. We present results of calculations concerning geothermal power plant efficiencies and energy production rates in both traditional reservoir-based systems and engineered geothermal systems (EGS) when CO2, rather than water, is used as the subsurface working fluid. While our previous studies have examined geologic systems with established CO2 plumes, we focus here on multicomponent (CO2 + brine) systems. Numerical simulations (e.g., Randolph and Saar, Geophysical Research Letters, 2011) indicate that CPG systems provide several times the heat energy recovery of similar water-based systems. Furthermore, the CPG method results in higher geothermal heat extraction efficiencies than both water- and CO2-based EGS. Therefore, CPG should further extend the applicability of geothermal energy utilization to regions with subsurface temperatures and heat flow rates that are even lower than those that may be added due to switching from water- to CO2-based EGS. Finally, simulations at present suggest that multicomponent effects - e.g., buoyant flow as CO2 rises over denser brine - may enhance heat extraction in CPG systems compared to traditional water-based geothermal approaches.

  17. 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.

  18. 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.

  19. Effect of modeling factors on the dissolution-diffusion-convection process during CO2 geological storage in deep saline formations

    Institute of Scientific and Technical Information of China (English)

    Wei ZHANG

    2013-01-01

    It is well known that during CO2 geological storage,density-driven convective activity can significantly accelerate the dissolution of injected CO2 into water.This action could limit the escape of supercritical CO2 from the storage formation through vertical pathways such as fractures,faults and abandoned wells,consequently increasing permanence and security of storage.First,we investigated the effect of numerical perturbation caused by time and grid resolution and the convergence criteria on the dissolution-diffusion-convection (DDC) process.Then,using the model with appropriate spatial and temporal resolution,some uncertainty parameters investigated in our previous paper such as initial gas saturation and model boundaries,and other factors such as relative liquid permeability and porosity modification were used to examine their effects on the DDC process.Finally,we compared the effect of 2D and 3D models on the simulation of the DDC process.The above modeling results should contribute to clear understanding and accurate simulation of the DDC process,especially the onset of convective activity,and the CO2 dissolution rate during the convection-dominated stage.

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

    Science.gov (United States)

    Räisänen, Jouni

    2016-08-01

    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.

  1. 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.

  2. 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

  3. Thermo-mechanical simulations of CO2 laser-fused silica interactions

    Science.gov (United States)

    Doualle, T.; Gallais, L.; Cormont, P.; Hébert, D.; Combis, P.; Rullier, J.-L.

    2016-03-01

    CO2 laser heating of silica glass is used in many scientific and industrial applications. Particularly, localized CO2 laser heating of silica glass has demonstrated its ability to mitigate surface damage on optics used for high power laser applications. To develop such applications, the control of temperature, heat affected area, and resulting mechanical stresses are critical. Therefore, it is necessary to understand the silica transformation, the material ejection, and the thermo-mechanical stresses induced by the laser heating and subsequent cooling. In this paper, we detail the development of comprehensive thermo-mechanical numerical simulations of these physical processes, based on finite-element method. The approach is developed for 2D or 3D cases to tackle the case of a moving beam at the surface of the sample, and we particularly discuss the choice of the different parameters based on bibliographic inputs. The thermal and mechanical numerical results have been compared to different dedicated experimental studies: infrared thermography measurements at the surface of the irradiated area, optical profilometry measurements of the laser-processed sites, and photo-elastic measurements. Very consistent results are obtained between numerical and experimental results for the description of the temperature gradients, the material ejection, and the residual stresses.

  4. Simulations couplées globales des changements climatiques associés à une augmentation de la teneur atmosphérique en CO 2

    Science.gov (United States)

    Barthelet, Pierre; Bony, Sandrine; Braconnot, Pascale; Braun, Alain; Cariolle, Daniel; Cohen-Solal, Emmanuelle; Dufresne, Jean-Louis; Delecluse, Pascale; Déqué, Michel; Fairhead, Laurent; Filiberti, Marie-Angèle; Forichon, Michelle; Grandpeix, Jean-Yves; Guilyardi, Eric; Hqussais, Marie-Noëlle; Imbard, Maurice; Le Treut, Hervé; Lévy, Claire; Xin Li, Zhao; Madec, Gurvan; Marquet, Pascal; Marti, Olivier; Planton, Serge; Terray, Laurent; Thual, Olivier; Valcke, Sophie

    1998-05-01

    Two transient CO 2 experiments using two coupled general circulation models developed by the French GASTON group have been realized using the same methodology. No flux corrections at the air-sea interface were used in these experiments. The main features of the present climate are reasonably well captured by both coupled models in the control simulations, although the biases are not the same, The transient CO 2 simulations show a global warming, ranging between 1.6 and 2.0 °C at the time of CO 2 doubling (+ 70 years). These values, and the main geographical characteristics of climate change, are in agreement with previous studies published by other research groups, using either flux corrected or non-flux corrected models.

  5. 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.

  6. 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.

  7. Use of a vehicle-modelling tool for predicting CO 2 emissions in the framework of European regulations for light goods vehicles

    Science.gov (United States)

    Fontaras, Georgios; Kouridis, Hariton; Samaras, Zissis; Elst, Daniel; Gense, Raymond

    The reduction of CO 2 emissions and fuel consumption from road transportation constitutes an important pillar of the EU commitment for implementing the Kyoto Protocol. Efforts to monitor and limit CO 2 emissions from vehicles can effectively be supported by the use of vehicle modelling tools. This paper presents the application of such a tool for predicting CO 2 emissions of vehicles under different operating conditions and shows how the results from simulations can be used for supporting policy analysis and design aiming at further reductions of the CO 2 emissions. For this purpose, the case of light duty goods (N1 category) vehicle CO 2 emissions control measures adopted by the EU is analysed. In order to understand how certain design and operating aspects affect fuel consumption, a number of N1 vehicles were simulated with ADVISOR for various operating conditions and the numerical results were validated against chassis dynamometer tests. The model was then employed for analysing and evaluating the new EU legislative framework that addresses CO 2 emissions from this vehicle class. The results of this analysis have shown the weaknesses of the current regulations and revealed new potential in CO 2 emissions control. Finally the TREMOVE model was used for simulating a possible scenario for reducing CO 2 emissions at fleet level.

  8. A poromechanical model for coal seams saturated with binary mixtures of CH4 and CO2

    Science.gov (United States)

    Nikoosokhan, Saeid; Vandamme, Matthieu; Dangla, Patrick

    2014-11-01

    Underground coal bed reservoirs naturally contain methane which can be produced. In parallel of the production of this methane, carbon dioxide can be injected, either to enhance the production of methane, or to have this carbon dioxide stored over geological periods of time. As a prerequisite to any simulation of an Enhanced Coal Bed Methane recovery process (ECBM), we need state equations to model the behavior of the seam when cleats are saturated with a miscible mixture of CH4 and CO2. This paper presents a poromechanical model of coal seams exposed to such binary mixtures filling both the cleats in the seam and the porosity of the coal matrix. This model is an extension of a previous work which dealt with pure fluid. Special care is dedicated to keep the model consistent thermodynamically. The model is fully calibrated with a mix of experimental data and numerical data from molecular simulations. Predicting variations of porosity or permeability requires only calibration based on swelling data. With the calibrated state equations, we predict numerically how porosity, permeability, and adsorbed amounts of fluid vary in a representative volume element of coal seam in isochoric or oedometric conditions, as a function of the pressure and of the composition of the fluid in the cleats.

  9. Geological characterization of Italian reservoirs and numerical 3D modelling of CO2 storage scenarios into saline aquifers

    Science.gov (United States)

    Beretta, S.; Moia, F.; Guandalini, R.; Cappelletti, F.

    2012-04-01

    The research activities carried out by the Environment and Sustainable Development Department of RSE S.p.A. aim to evaluate the feasibility of CO2 geological sequestration in Italy, with particular reference to the storage into saline aquifers. The identification and geological characterization of the Italian potential storage sites, together with the study of the temporal and spatial evolution of the CO2 plume within the caprock-reservoir system, are performed using different modelling tools available in the Integrated Analysis Modelling System (SIAM) entirely powered in RSE. The numerical modelling approach is the only one that allows to investigate the behaviour of the injected CO2 regarding the fluid dynamic, geochemical and geomechanical aspects and effects due to its spread, in order to verify the safety of the process. The SIAM tools allow: - Selection of potential Italian storage sites through geological and geophysical data collected in the GIS-CO2 web database; - Characterization of caprock and aquifer parameters, seismic risk and environmental link for the selected site; - Creation of the 3D simulation model for the selected domain, using the modeller METHODRdS powered by RSE and the mesh generator GMSH; - Simulation of the injection and the displacement of CO2: multiphase fluid 3D dynamics is based on the modified version of TOUGH2 model; - Evaluation of geochemical reaction effects; - Evaluation of geomechanic effects, using the coupled 3D CANT-SD finite elements code; - Detailed local analysis through the use of open source auxiliary tools, such as SHEMAT and FEHM. - 3D graphic analysis of the results. These numerical tools have been successfully used for simulating the injection and the spread of CO2 into several real Italian reservoirs and have allowed to achieve accurate results in terms of effective storage capacity and safety analysis. The 3D geological models represent the high geological complexity of the Italian subsoil, where reservoirs are

  10. Feasible study of international cooperation on the long-term scenario for reducing CO2. DNE-21 simulation database; CO2 sakugen ni kakawaru choki scenario ni kansuru kokusai kyoryoku kanosei chosa. DNE21 simulation database

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    This report describes calculation codes of DNE-21 which can simulate the optimization model for reducing CO2. The DNE-21 was modified from the former NE-21. The term was set between 2000 and 2100. Optimization can be conducted across the different time. Non-conventional petroleum was removed from the primary energy. Capacity of nuclear power generation facilities was taken in the model for the optimization. Decision making analysis can be done by considering the uncertainty. The DNE-21 has eleven input files including the model operation, technical property related data, cost related data, data of tax, subsidy and customs, and scenario data of future energy demand and supply, GNP, population and nuclear power. The DNE-21 has fifteen output files including the optimization calculation results for the world, Oceania, the Middle East, North Africa, Central America, South America, former USSR, and OECD countries. 2 figs.

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

    Science.gov (United States)

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

    2009-01-01

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

  12. Validation of the CO2/N2O analogy using molecular simulation

    NARCIS (Netherlands)

    Chen, Q.; Balaji, S.P.; Ramdin, M.; Gutiérrez-Sevillano, J.J.; Bardow, A.; Goetheer, E.L.V.; Vlugt, T.J.H.

    2014-01-01

    CO2 readily reacts in aqueous amine solutions. The properties of free CO2 in amine solutions are therefore difficult to obtain directly and are often predicted from the nonreacting molecule N2O due to the similarities in mass and structure. This often-used empirical "CO2/N2O analogy" is verified in

  13. Modeling of CO2 solubility in single and mixed electrolyte solutions using statistical associating fluid theory

    Science.gov (United States)

    Jiang, Hao; Panagiotopoulos, Athanassios Z.; Economou, Ioannis G.

    2016-03-01

    Statistical associating fluid theory (SAFT) is used to model CO2 solubilities in single and mixed electrolyte solutions. The proposed SAFT model implements an improved mean spherical approximation in the primitive model to represent the electrostatic interactions between ions, using a parameter K to correct the excess energies ("KMSA" for short). With the KMSA formalism, the proposed model is able to describe accurately mean ionic activity coefficients and liquid densities of electrolyte solutions including Na+, K+, Ca2+, Mg2+, Cl-, Br- and SO42- from 298.15 K to 473.15 K using mostly temperature independent parameters, with sole exception being the volume of anions. CO2 is modeled as a non-associating molecule, and temperature-dependent CO2-H2O and CO2-ion cross interactions are used to obtain CO2 solubilities in H2O and in single ion electrolyte solutions. Without any additional fitting parameters, CO2 solubilities in mixed electrolyte solutions and synthetic brines are predicted, in good agreement with experimental measurements.

  14. A cell-based model for the photoacclimation and CO(2)-acclimation of the photosynthetic apparatus.

    Science.gov (United States)

    Papadakis, I A; Kotzabasis, K; Lika, K

    2005-06-30

    We have developed a mathematical model based on the underlying mechanisms concerning the responses of the photosynthetic apparatus of a microalga cell which grows under constant incident light intensity and ambient CO(2) concentration. Photosynthesis involves light and carbon-fixation reactions which are mutually dependent and affect each other, but existing models for photosynthesis don't account for both reactions at once. Our modeling approach allows us to derive distinct equations for the rates of oxygen production, NADPH production, carbon dioxide fixation, carbohydrate production, and rejected energy, which are generally different. The production rates of the photosynthesis products are hyperbolic functions of light and CO(2) concentration. The model predicts that in the absence of photoinhibition, CO(2)-inhibition, photorespiration, and chlororespiration, a cell acclimated to high light and/or CO(2) concentration has higher photosynthetic capacity and lower photosynthetic efficiency than does a cell acclimated to low conditions. This results in crossing between the two curves which represent the oxygen production rates and carbon fixation rates in low and high conditions. Finally, in the absence of photoinhibition and CO(2)-inhibition, the model predicts the carbohydrate production rate in terms of both light intensity and CO(2) concentration.

  15. 华北地区油松林生态系统对气候变化和CO2浓度升高的响应——基于BIOME-BGC模型和树木年轮的模拟%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

    Institute of Scientific and Technical Information of China (English)

    彭俊杰; 何兴元; 陈振举; 崔明星; 张先亮; 周长虹

    2012-01-01

    应用BIOME-BGC模型和树木年轮数据模拟1952-2008年华北地区典型油松林生态系统净初级生产力(NPP)动态,探究了树木径向生长和NPP对区域气候变暖的响应以及未来气候情景下油松林生态系统NPP动态变化.结果表明:1952-2008年,研究区油松林生态系统NPP波动于244.12 ~645.31 g C·m-2·a-1,平均值为418.6 g C·m-2·a-1.5-6月的平均温度和上年8月至当年7月的降水是限制该地区油松径向生长和油松林生态系统NPP的主要因子.研究期间,随着区域暖干化趋势的加强,树木径向生长和生态系统NPP均呈下降趋势.未来气候情景下,NPP对温度和降水的单独和复合变化的响应为正向.CO2浓度升高有利于油松林生态系统NPP的增加,CO2的施肥效应使NPP增加16.1%.在生态系统和区域水平,树木年轮是一种理想的指示生态系统动态变化的代用资料,可以检验和校正包括BIOME-BGC模型在内的各种生态系统过程模型.%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 · m-2 · a-1, with a mean value of 418. 6 g C · m-2 · 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

  16. Forecasting global atmospheric CO2

    Directory of Open Access Journals (Sweden)

    A. Agustí-Panareda

    2014-05-01

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

  17. Simulation of the crosshole ERT monitoring of the CO2 migration at the Research Laboratory on Geological Storage of CO2 in Hontomín (Burgos, Spain): assessing its feasibility and the optimal configuration

    Science.gov (United States)

    Vilamajó, Eloi; Bellmunt, Fabian; Queralt, Pilar; Marcuello, Álex; Ledo, Juanjo

    2013-04-01

    The Research Laboratory on Geological Storage of CO2 located in Hontomín (Burgos, Spain) is a multidisciplinary Technological Demonstration Plant oriented to test the geological storage of carbon dioxide in an onshore saline reservoir. Due to its academic orientation, it will provide a wide set of data obtained with complementary geophysical techniques. In order to allow the integration of the respective results, several geophysical methods will be used on the monitoring process of the storage of CO2 into a deep saline aquifer. The resistivity of the storage formation will be one of the geophysical properties most affected by the replacement of the conductive brine by resistive carbon dioxide. As the electrical and electromagnetic methods are the techniques most sensitive to such change, their use on the monitoring process of the Hontomín TDP will provide important insights on the migration of CO2. The current work is integrated in the electric and electromagnetic monitoring of the CO2 storage at Hontomín, where two boreholes (injection and monitoring) will be drilled beneath the injection depth. A set of electrodes is planned to be installed at the two wells allowing advantageous experiments in order to determine the resistivity variation into the reservoir. Crosshole ERT and CSEM experiments will be carried out previously to the injection of carbon dioxide and repeated systematically once the storage has started. The feasibility of the crosshole ERT monitoring is evaluated in the current work. Realistic pre-injection and post-injection experiments have been modeled to assess the potentiality and benefits of the crosshole ERT in order to monitor the stored CO2. A geoelectrical model obtained from previous characterization works has been used to describe the geoelectrical structure. The metallic casings planned to be installed at the two wells are considered in the simulations, given their possible effect on the experiments. Sets of synthetic data are generated

  18. 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

  19. Corrosion Behaviors of PI 10 Steel and Chromium Coating in CO2-saturated Simulated Oilfield Brine

    Institute of Scientific and Technical Information of China (English)

    LIN Naiming; XIE Faqin; ZHOU Jun; WU Xiangqing; TIAN Wei

    2011-01-01

    The protective chromium coating was prepared on P110 steel by employing pack cementation. The corrosion behaviors of P110 steel and the obtained coating in CO2-saturated simulated oilfield brine were studied by static complete immersion tests and electrochemical measurements.The corrosion attacks of the samples were determined by mass loss, corroded surface morphologies,corrosion products, and results of electrochemical measurements. The experimental results showed that the coating was uniform, continuous and compact. The chromium coating was slightly corroded,and the mass loss and corrosion rate of the coating were far lower than those of P110 steel. Chromium coating has higher self-corroding potential and lower corrosion current density than P110 steel in accordance with the electrochemical tests results. Taken as a whole, chromizing treatment has significantly improved the corrosion resistance of P110 steel.

  20. A first-order analysis of the potential role of CO2 fertilization to affect the global carbon budget: A comparison of four terrestrial biosphere models

    Science.gov (United States)

    Kicklighter, D.W.; Bruno, M.; Donges, S.; Esser, G.; Heimann, Martin; Helfrich, J.; Ift, F.; Joos, F.; Kaduk, J.; Kohlmaier, G.H.; McGuire, A.D.; Melillo, J.M.; Meyer, R.; Moore, B.; Nadler, A.; Prentice, I.C.; Sauf, W.; Schloss, A.L.; Sitch, S.; Wittenberg, U.; Wurth, G.

    1999-01-01

    We compared the simulated responses of net primary production, heterotrophic respiration, net ecosystem production and carbon storage in natural terrestrial ecosystems to historical (1765 to 1990) and projected (1990 to 2300) changes of atmospheric CO2 concentration of four terrestrial biosphere models: the Bern model, the Frankfurt Biosphere Model (FBM), the High-Resolution Biosphere Model (HRBM) and the Terrestrial Ecosystem Model (TEM). The results of the model intercomparison suggest that CO2 fertilization of natural terrestrial vegetation has the potential to account for a large fraction of the so-called 'missing carbon sink' of 2.0 Pg C in 1990. Estimates of this potential are reduced when the models incorporate the concept that CO2 fertilization can be limited by nutrient availability. Although the model estimates differ on the potential size (126 to 461 Pg C) of the future terrestrial sink caused by CO2 fertilization, the results of the four models suggest that natural terrestrial ecosystems will have a limited capacity to act as a sink of atmospheric CO2 in the future as a result of physiological constraints and nutrient constraints on NPP. All the spatially explicit models estimate a carbon sink in both tropical and northern temperate regions, but the strength of these sinks varies over time. Differences in the simulated response of terrestrial ecosystems to CO2 fertilization among the models in this intercomparison study reflect the fact that the models have highlighted different aspects of the effect of CO2 fertilization on carbon dynamics of natural terrestrial ecosystems including feedback mechanisms. As interactions with nitrogen fertilization, climate change and forest regrowth may play an important role in simulating the response of terrestrial ecosystems to CO2 fertilization, these factors should be included in future analyses. Improvements in spatially explicit data sets, whole-ecosystems experiments and the availability of net carbon exchange

  1. Simulation and prediction of CO2 emission reductions of biogas industry in China%中国沼气产业对减排CO2的模拟与预测

    Institute of Scientific and Technical Information of China (English)

    杨艳丽; 李光全; 张培栋

    2013-01-01

    . Therefore, it would be very useful to develop a simple and fast method to estimate CO2 emissions reduction by biogas utilization. This thesis research is about the application of composite regression method in estimating the process of CO2 emissions reduction by biogas utilization;the research indices include biomass resource, structure of rural living energy, and biogas development condition. The results showed that the amounts of rural household biogas digester, biogas production per household and the digester volumes of middle-scale biogas project were significant impact factors of CO2 emissions reduction by biogas utilization in China. Among which, there was prominent linear relation between the amounts of rural household biogas digester and CO2 emission reductions with correlation coefficient (R2) equal to 0.992 and error rate less than 5%, S function relations between biogas production per household and CO2 emission reductions with correlation coefficient (R2) of 0.677 and error rate below 5%, and linear relation between the digester volumes of middle-scale biogas project and CO2 emissions reduction with correlation coefficient (R2) of 0.977 and error rate less than 2%. It indicated that all the simulation results were trustworthy and useful, that was to say the composite regression model that composed by multiple linear regression and curve fitting could effectively reflect the numerical relations between CO2 emissions reduction and influencing factors, also could be applied to predict the CO2 ER by biogas utilization. According the 12 th Five Year Development Program for Renewable Energy, the prediction results based on the method above indicated that the CO2 emissions reduction of biogas utilization could reach 6.18×107-1.38×108 t in 2015. It is an effective way for keeping important station of reducing greenhouse gas emissions to strengthen research on biogas utilization technology, and promoting biogas project development in livestock farms.

  2. 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

  3. A regional CO2 observing system simulation experiment for the ASCENDS Satellite Mission

    Directory of Open Access Journals (Sweden)

    J. S. Wang

    2014-05-01

    Full Text Available 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° latitude × 1° 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° × 1°, weekly scale, 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 from ∼65% to ∼85% for the continent as a whole. Our uncertainty reductions at various scales are

  4. 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.

  5. Modeling some long-term implications of CO2 fertilization for global forests and forest industries

    Institute of Scientific and Technical Information of China (English)

    Joseph; Buongiorno

    2016-01-01

    Background:This paper explored the long-term, ceteris-paribus effects of potential CO2 fertilization on the global forest sector. Based on the findings of Norby et al. (PNAS 2005, 102(50)) about forest response to elevated [CO2]. Methods:Forest productivity was increased in the Global Forest Products Model (GFPM) in proportion to the rising [CO2] projected in the IPCC scenario A1B, A2, and B2. Projections of the forest area and forest stock and of the production, consumption, prices, and trade of products ranging from fuelwood to paper and paperboard were obtained with the GFPM for each scenario, with and without CO2 fertilization beginning in 2011 and up to 2065. Results:CO2 fertilization increased wood supply, leading to lower wood prices which in turn induced modest lower prices of end products and higher global consumption. However, production and value added in industries decreased in some regions due to the relative competitive advantages and to the varying regional effects of CO2 fertilization. Conclusion:The main effect of CO2 fertilization was to raise the level of the world forest stock in 2065 by 9 to 10%for scenarios A2 and B2 and by 20%for scenario A1B. The rise in forest stock induced by fertilization was in part counteracted by its stimulation of the wood supply which resulted in lower wood prices and increased harvests.

  6. Numerical modeling of time-lapse monitoring of CO2 sequestration in a layered basalt reservoir

    Science.gov (United States)

    Khatiwada, M.; Van Wijk, K.; Clement, W.P.; Haney, M.

    2008-01-01

    As part of preparations in plans by The Big Sky Carbon Sequestration Partnership (BSCSP) to inject CO2 in layered basalt, we numerically investigate seismic methods as a noninvasive monitoring technique. Basalt seems to have geochemical advantages as a reservoir for CO2 storage (CO2 mineralizes quite rapidly while exposed to basalt), but poses a considerable challenge in term of seismic monitoring: strong scattering from the layering of the basalt complicates surface seismic imaging. We perform numerical tests using the Spectral Element Method (SEM) to identify possibilities and limitations of seismic monitoring of CO2 sequestration in a basalt reservoir. While surface seismic is unlikely to detect small physical changes in the reservoir due to the injection of CO2, the results from Vertical Seismic Profiling (VSP) simulations are encouraging. As a perturbation, we make a 5%; change in wave velocity, which produces significant changes in VSP images of pre-injection and post-injection conditions. Finally, we perform an analysis using Coda Wave Interferometry (CWI), to quantify these changes in the reservoir properties due to CO2 injection.

  7. CO2 conversion in a gliding arc plasma: 1D cylindrical discharge model

    Science.gov (United States)

    Wang, Weizong; Berthelot, Antonin; Kolev, Stanimir; Tu, Xin; Bogaerts, Annemie

    2016-12-01

    CO2 conversion by a gliding arc plasma is gaining increasing interest, but the underlying mechanisms for an energy-efficient process are still far from understood. Indeed, the chemical complexity of the non-equilibrium plasma poses a challenge for plasma modeling due to the huge computational load. In this paper, a one-dimensional (1D) gliding arc model is developed in a cylindrical frame, with a detailed non-equilibrium CO2 plasma chemistry set, including the CO2 vibrational kinetics up to the dissociation limit. The model solves a set of time-dependent continuity equations based on the chemical reactions, as well as the electron energy balance equation, and it assumes quasi-neutrality in the plasma. The loss of plasma species and heat due to convection by the transverse gas flow is accounted for by using a characteristic frequency of convective cooling, which depends on the gliding arc radius, the relative velocity of the gas flow with respect to the arc and on the arc elongation rate. The calculated values for plasma density and plasma temperature within this work are comparable with experimental data on gliding arc plasma reactors in the literature. Our calculation results indicate that excitation to the vibrational levels promotes efficient dissociation in the gliding arc, and this is consistent with experimental investigations of the gliding arc based CO2 conversion in the literature. Additionally, the dissociation of CO2 through collisions with O atoms has the largest contribution to CO2 splitting under the conditions studied. In addition to the above results, we also demonstrate that lumping the CO2 vibrational states can bring a significant reduction of the computational load. The latter opens up the way for 2D or 3D models with an accurate description of the CO2 vibrational kinetics.

  8. Sensitivity of Global and Regional Terrestrial Carbon Storage to the Direct CO2 Effect and Climate Change Based on the CMIP5 Model Intercomparison

    OpenAIRE

    Jing Peng; Li Dan; Mei Huang

    2014-01-01

    Global and regional land carbon storage has been significantly affected by increasing atmospheric CO2 concentration and climate change. Based on fully coupled climate-carbon-cycle simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we investigate sensitivities of land carbon storage to rising atmospheric CO2 concentration and climate change over the world and 21 regions during the 130 years. Overall, the simulations suggest that consistently spatial positive effects of...

  9. Experimental and modeling study of NO emission under high CO2 concentration

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An experimental and numerical study of the NOx formation and reduction process in a designed coal combustion furnace under both traditional air atmosphere and O2/CO2 atmosphere was conducted, in an attempt to explore the chemistry mechanism of the experimentally observed NOx suppression under high CO2 concentration atmospheres. A simplified ‘chemically oriented’ approach, computational fluid dynamics (CFD)-chemical kinetics modeling method, was validated and used to model the experimental process. The high CO2 concentration’s chemical effect on NO reduction has been studied, and the differences in NOx reaction behaviors between O2/CO2 atmosphere and air atmosphere were analyzed by detailed chemical kinetic model. On the basis of investigations through elementary chemical reactions, it can be concluded that high CO2 concentration plays an important role on NOx conversion process during oxy-fuel combustion. Moreover, the dominant reaction steps and the most important reactions for NO conversion under different atmospheres were discussed. Under O2/CO2 atmosphere, the main active sequence for NO reaction includes: NO→N→N2, and the main active path for NO reaction under air atmosphere is through N2→N→NO.

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

    Science.gov (United States)

    Kuenemann, Melaine A; Fourches, Denis

    2017-03-07

    As stricter regulations on CO2 emissions are adopted worldwide, identifying efficient chemical processes to capture and recycle CO2 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 CO2 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' CO2 absorption properties from their structural characteristics. These models afforded reasonable prediction performances (e. g., Q(2)LOO =0.63 for CO2 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 CO2 absorption properties.

  11. Level-lumping method for the modeling of CO2 vibrational kinetics

    Science.gov (United States)

    Berthelot, Antonin; Bogaerts, Annemie; University of Antwerp, Plasmant Team

    2016-09-01

    The conversion of greenhouse gases, especially CO2, into value-added chemicals is gaining a very large interest among the scientific and industrial communities. It is known that the excitation of the asymmetric vibrational mode of CO2 is one of the most important processes to achieve high energy efficiencies, thus making the CO2 kinetics very complex. Due to this complexity, the only models that have been developed so far were zero-dimensional models, considering only the variations over time. These models require strong approximations on the geometry of the reactor. In order to reduce the calculation time and to allow the modeling of complex plasma problems in 2D or 3D geometries, we have simplified the chemistry set of CO2 and developed a lumped-levels model for the vibrational kinetics. It was found that a 3-groups model gives a good agreement with the state-to-state model at pressures of 100mbar and above, at the conditions under study. The important dissociation and recombination mechanisms of CO2 have also been investigated. This lumped-levels model is being implemented in a 2D self-consistent microwave plasma code. This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 606889.

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

    Science.gov (United States)

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

    2015-12-01

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

  13. 基于钙循环的燃煤电站捕集CO2系统模拟%System simulation of CO2 capture for coal-fired power plant based on calcium looping cycle

    Institute of Scientific and Technical Information of China (English)

    李英杰

    2011-01-01

    提出一种基于钙循环法适用于燃煤电站的燃气/蒸汽联合循环捕集CO2新型系统,把该CO2捕集系统分成4个子系统:煤气化子系统、燃气子系统、钙循环捕集CO2子系统、余热锅炉及汽水循环子系统.采用Aspen Plus软件平台对各子系统进行热力学建模和模拟.结果表明,在CO2捕集效率为90%时,在一定钙基吸收剂流量参数下该CO2捕集系统的净效率可达41.81%.氧碳物质的量比和汽碳物质的量比对气化炉煤气中的CO、H2和CH4体积分数有重要影响.随着氧碳比和汽碳比的增加,煤气热值和CO2捕集系统净效率均呈现下降趋势.为了保持较高的系统净效率,氧碳比应小于0.24.%A new cyclic CO2 capture system based on calcium looping cycle using gas/steam combined cycle for coalfired plant was proposed.The CO2 capture system was divided into four subsystems:coal gasification subsystem, gas subsystem, calcium cyclic capturing CO2 subsystem and HRSG and steam-water circulation subsystem.The thermodynamic modeling and simulation for the subsystems were performed by Aspen Plus software platform.The results show that the net efficiency of the CO2 capture system reaches 41.81% at the CO2 capture efficiency of 90% with the certain flow parameter of calcium-based sorbent.The oxygen/carbon molar ratio and steam/carbon molar ratio exhibit a significant effect on the volume fraction of CO, H2 and CH4 in the gas from the gasifier.The heat value of the gas and net efficiency of the CO2 capture system show a decrease with increasing the oxygen/carbon and team/carbon molar ratios.The molar ratio of oxygen/carbon should be less than 0.24 in order to keep the high system net efficiency.

  14. Modeling vertical stratification of CO 2 injected into a deep layered aquifer

    Science.gov (United States)

    Hayek, Mohamed; Mouche, Emmanuel; Mügler, Claude

    2009-03-01

    The vertical stratification of carbon dioxide (CO 2) injected into a deep layered aquifer made up of high-permeability and low-permeability layers, such as Utsira aquifer at Sleipner site in Norway, is investigated with a Buckley-Leverett equation including gravity effects. In a first step, we study both by theory and simulation the application of this equation to the vertical migration of a light phase (CO 2), in a denser phase (water), in 1D vertical columns filled with different types of porous media: homogeneous, piecewise homogeneous, layered periodic and finally heterogeneous. For each case, we solve the associated Riemann problems and propose semi-analytical solutions describing the spatial and temporal evolution of the light phase saturation. These solutions agree well with simulation results. We show that the flux continuity condition at interfaces between high-permeability and low-permeability layers leads to CO 2 saturation discontinuities at these interfaces and, in particular, to a saturation increase beneath low-permeability layers. In a second step, we analyze the vertical migration of a CO 2 plume injected into a 2D layered aquifer. We show that the CO 2 vertical stratification under each low-permeability layer is induced, as in 1D columns, by the flux continuity condition at interfaces. As the injection takes place at the bottom of the aquifer the velocity and the flux function decrease with elevation and this phenomenon is proposed to explain the stratification under each mudstone layer as observed at Sleipner site.

  15. Towards understanding the variability in biospheric CO2 fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2015-09-01

    Full Text Available Understanding carbon dioxide (CO2 biospheric processes is of great importance because the terrestrial exchange drives the seasonal and inter-annual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake and respiration (production. Carbonyl sulfide (OCS could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential mean to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at three selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem. The OCS simulations are driven by different land biospheric fluxes to reproduce the seasonality of the measurements. Increasing the plant uptake of Kettle et al. (2002a by a factor of three resulted in the best comparison with FTIR measurements. However, there are still discrepancies in the latitudinal distribution when comparing with HIPPO (HIAPER Pole-to-Pole Observations data spanning both hemispheres. The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB are used in the study and compared to measurements. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a

  16. Modeling of CBM production, CO2 injection, and tracer movement at a field CO2 sequestration site

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Hema J.; Bowes, Benjamin D.; Bromhal, Grant S.; Gondle, Raj K.; Wells, Arthur W.; Strazisar, Brian R.

    2012-07-01

    Sequestration of carbon dioxide in unmineable coal seams is a potential technology mainly because of the potential for simultaneous enhanced coalbed methane production (ECBM). Several pilot tests have been performed around the globe leading to mixed results. Numerous modeling efforts have been carried out successfully to model methane production and carbon dioxide (CO{sub 2}) injection. Sensitivity analyses and history matching along with several optimization tools were used to estimate reservoir properties and to investigate reservoir performance. Geological and geophysical techniques have also been used to characterize field sequestration sites and to inspect reservoir heterogeneity. The fate and movement of injected CO{sub 2} can be determined by using several monitoring techniques. Monitoring of perfluorocarbon (PFC) tracers is one of these monitoring technologies. As a part of this monitoring technique, a small fraction of a traceable fluid is added to the injection wellhead along with the CO{sub 2} stream at different times to monitor the timing and location of the breakthrough in nearby monitoring wells or offset production wells. A reservoir modeling study was performed to simulate a pilot sequestration site located in the San Juan coal basin of northern New Mexico. Several unknown reservoir properties at the field site were estimated by modeling the coal seam as a dual porosity formation and by history matching the methane production and CO{sub 2} injection. In addition to reservoir modeling of methane production and CO{sub 2} injection, tracer injection was modeled. Tracers serve as a surrogate for determining potential leakage of CO{sub 2}. The tracer was modeled as a non-reactive gas and was injected into the reservoir as a mixture along with CO{sub 2}. Geologic and geometric details of the field site, numerical modeling details of methane production, CO{sub 2} injection, and tracer injection are presented in this paper. Moreover, the numerical

  17. Biocompatibility of supercritical CO2-treated titanium implants in a rat model.

    Science.gov (United States)

    Hill, C M; Kang, Q K; Wahl, C; Jimenez, A; Laberge, M; Drews, M; Matthews, M A; An, Y H

    2006-04-01

    Supercritical phase CO2 is a promising method for sterilizing implantable devices and tissue grafts. The goal of this study is to evaluate the biocompatibility of titanium implants sterilized by supercritical phase CO2 in a rat subcutaneous implantation model. At 5 weeks post implantation titanium implants sterilized by supercritical phase CO2 produce a soft tissue reaction that is comparable to other methods of sterilization (steam autoclave, ultraviolet light radiation, ethylene oxide gas, and radio-frequency glow-discharge), as indicated by the thickness and density of the foreign body capsule, although there were some differences on the capillary density. Overall the soft tissue response to the implants was similar among all methods of sterilization, indicating supercritical phase CO2 treatment did not compromise the biocompatibility of the titanium implant.

  18. 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

  19. 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 withi

  20. Simulating soil N2O emissions and heterotrophic CO2 respiration in arable systems using FASSET and MoBiLE-DNDC

    DEFF Research Database (Denmark)

    Chirinda, Ngonidzashe; Kracher, Daniela; Lægdsmand, Mette;

    2011-01-01

    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......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...... 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...

  1. Co-Sequestration Geochemical Modeling: Simple Brine Solution + CO2-O2-SO2

    Science.gov (United States)

    Verba, C.; Kutchko, B. G.; Reed, M. H.

    2012-12-01

    Class H well cement (LaFarge) was exposed to supercritical CO2 to evaluate the impact of brine chemistry on the well cement. Simulated experimental downhole conditions include a pressure of 28.6 MPa and a temperature of 50oC. Brine composition was formulated from the NETL NATCARB database, resulting in a simple solution of 1 M (NaCl, MgCl2, CaCl2). It was determined that the brine chemistry plays a vital role in determining the degree and type of alteration of cement in carbon sequestration conditions. The implications of co-sequestration (CO2/O2/SO2 mixtures) from of oxy-fueled combustion, coal gasification and sour gas have been considered. Geochemical modeling was conducted to understand the interaction between formation brine, cement and co-contaminant gases, using a gas composition of 95.5% CO2, 4% O2, and 1.5% SO2. The modeling results are significant in determining the validity of co-sequestering coal flue gas containing SOx gases or sour hydrocarbon gas which could potentially produce pyrite or other sulfur-bearing species in the cement via mineralization trapping. Thermodynamic components of aqueous species, gases, and minerals were used to calculate the pH and mineral saturation indices using CHIM-XPT. The computed pH of the solution is 4.34. The total sulfate molality within the brine is 0.0095 M. In experimental conditions of 600 mL of brine, 0.0057 moles of sulfate will be converted into 5.7 mL of sulfuric acid. The modeling shows that an excess of 31% O2 forms, indicating that H2S from SO2 disporportionation is oxidized to sulfate, thus no gaseous H2S will form. Remaining SO2 in the experimental headspace has a predicted mole fraction is 10-46. Additional SO2 gas added to the system produces the reaction to precipitate gypsum. Additional gas reactions precipitate gypsum, anhydrite, calcite, and dolomite.

  2. Development of CO2 inversion system based on the adjoint of the global coupled transport model

    Science.gov (United States)

    Belikov, Dmitry; Maksyutov, Shamil; Chevallier, Frederic; Kaminski, Thomas; Ganshin, Alexander; Blessing, Simon

    2014-05-01

    limited regions close to the monitoring sites (using the LPDM part), and at coarse resolution for the rest of the globe (using the Eulerian part), minimizing aggregation errors and computation cost. The adjoint of the coupled high-resolution Eulerian-Lagrangian model will be incorporated into the PYVAR CO2 variational inverse system (Chevallier et al., 2005). Chevallier, F., Fisher, M., Peylin, P., Serrar, S., Bousquet, P., Bréon, F.-M., Chédin, A., and Ciais, P.: Inferring CO2 sources and sinks from satellite observations: method and application to TOVS data, J. Geophys. Res., 110, D24309, doi:10.1029/2005JD006390, 2005.

  3. 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.

  4. Three-Dimensional Modeling of the Reactive Transport of CO2 and Its Impact on Geomechanical Properties of Reservoir Rocks and Seals

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Hou, Zhangshuan; Bacon, Diana H.; Murray, Christopher J.; White, Mark D.

    2016-01-04

    This article develops a novel multiscale modeling approach to analyze CO2 reservoirs using Pacific Northwest National Laboratory’s STOMP-CO2-R code that is interfaced with the ABAQUS® finite element package. The STOMP-CO2-R/ABAQUS® sequentially coupled simulator accounts for the reactive transport of CO2 causing mineral composition changes that modify the geomechanical properties of reservoir rocks and seals. Formation rocks’ elastic properties that vary during CO2 injection and govern the poroelastic behavior of rocks are modeled by an Eshelby-Mori-Tanka approach (EMTA) implemented in ABAQUS® via user-subroutines. The computational tool incorporates the change in rock permeability due to both geochemistry and geomechanics. A three-dimensional (3D) STOMP-CO2-R model for a model CO2 reservoir containing a vertical fault is built to analyze a formation containing a realistic geochemical reaction network with 5 minerals: albite, anorthite, calcite, kaolinite and quartz. A 3D ABAQUS® model that maps the above STOMP-CO2-R model is built for the analysis using STOMP-CO2-R/ABAQUS®. The results show that the changes in volume fraction of minerals include dissolution of anorthite, precipitation of calcite and kaolinite, with little change in the albite volume fraction. After a long period of CO2 injection the mineralogical and geomechanical changes significantly reduced the permeability and elastic modulus of the reservoir (between the base and caprock) in front of the fault leading to a reduction of the pressure margin to fracture at and beyond the injection location. The impact of reactive transport of CO2 on the geomechanical properties of reservoir rocks and seals are studied in terms of mineral composition changes that directly affect the rock stiffness, stress and strain distributions as well as the pressure margin to fracture.

  5. Weathering by tree-root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    OpenAIRE

    2014-01-01

    Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 concentrations ([CO2]a) over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation. However, the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geo...