Showing papers in "Greenhouse Gases-Science and Technology in 2015"
TL;DR: In this article, the effects of well geometry on seismic rupture and CO2 leakage were investigated in two different cases of injection through a vertical and a horizontal well, and the results showed a slightly higher leakage rate for the vertical well in the region close to the well itself, while leakage resulting from injection through the horizontal well is more widely distributed.
Abstract: Injection or withdrawal of fluid at depth may trigger felt seismicity. Such human-induced seismicity is a key environmental concern related to the exploitation of natural underground resources. Thus, understanding how to avoid triggering felt earthquakes plays a crucial role in the success of underground anthropogenic activities, such as CO2 geological storage. In this work, we conduct 3D simulations of injection-triggered fault reactivation, in order to investigate the effects of well geometry on seismic rupture and CO2 leakage. We analyze two different cases of injection, through (1) a vertical and (2) a horizontal well. Simulation results for the vertical well show the fault pressurizing faster and more locally than for the horizontal well, resulting in a smaller seismic event. For the horizontal well, the pressure is distributed over a wider area along the fault, which requires a longer time to reactivate, but results in a larger event. Fault reactivation also produces changes in damage-zone and fault-core permeability, allowing the CO2 to leak from the injection zone through overlying caprock, toward shallower depths. Although the calculated fault permeability enhancement is similar for the two cases, results show a slightly higher leakage rate for the vertical well in the region close to the well itself, while the leakage resulting from injection through the horizontal well is more widely distributed.Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
69 citations
TL;DR: In this article, a review of the advances in the catalytic conversion of CO2 into carboxylic acid derivatives from alkenes, alkynes, aromatic halides, aromatic C(sp2)-H bonds, etc.
Abstract: Chemical utilization of the greenhouse gas, i.e., CO2 as an abundant, easily available, and renewable carbon feedstock for producing chemicals, materials, and fuels is attractive as an integral part of the carbon cycle. Based on the principle of CO2 activation and elaborately designed catalysts, various transformation of CO2 can be realized under mild conditions. In particular, establishing practical methodologies for catalytic carboxylation by CO2 as carboxylative reagent would be a fascinating dream for synthetic chemists. This review covers the updated advances in the catalytic conversion of CO2 into carboxylic acid derivatives from alkenes, alkynes, aromatic halides, aromatic C(sp2)-H bonds, etc.
48 citations
TL;DR: In this paper, the authors take the time-lapse seismic monitoring data from the Sleipner storage operation to demonstrate that as more seismic data becomes available with time, predictive models can be matched more accurately to observations and become more reliable predictors of future performance.
Abstract: One of the three key regulatory requirements in Europe for transfer of storage site liability is to demonstrate conformity between predictive models of reservoir performance and monitoring observations. This is a challenging requirement because a perfect and unique match between observed and modeled behavior is near impossible to achieve. This study takes the time-lapse seismic monitoring data from the Sleipner storage operation to demonstrate that as more seismic data becomes available with time, predictive models can be matched more accurately to observations and become more reliable predictors of future performance. Six simple performance measures were defined: plume footprint area, maximum lateral migration distance of CO2 from the injection point, area of CO2 accumulation trapped at top reservoir, volume of CO2 accumulation trapped at top reservoir, area of all CO2 layers summed, and spreading co-efficient. Model scenarios were developed to predict plume migration up to 2008. Scenarios were developed for 1996 (baseline), 2001, and 2006 conditions, with models constrained by the information available at those times, and compared with monitoring datasets obtained up to 2008. The 1996 predictive range did generally encompass the future observed plume behavior, but with such a wide range of uncertainty as to render it of only marginal practical use. The 2001 predictions (which used the 1999 and 2001 seismic monitoring datasets) had a much lower uncertainty range, with the 2006 uncertainties somewhat lower again. There are still deficiencies in the actual quality of match but a robust convergence, with time, of predicted and observed models is clearly demonstrated. We propose modeling-monitoring convergence as a generic approach to demonstrating conformance.
48 citations
TL;DR: In this article, nano-porous sodium zeolite-Y (NaY Zeolite) particles were incorporated into the dense (homogeneous) cellulose acetate (CA) membrane to prepare the CA/NaY mixed matrix membranes.
Abstract: The aim of this research is to investigate the fabrication and evaluation of a new mixed matrix membrane for CO2/N2 separation. Micro-sized nano-porous sodium zeolite-Y (NaY zeolite) particles (0–25 wt.%) were incorporated into the dense (homogeneous) cellulose acetate (CA) membrane to prepare the CA/NaY mixed matrix membranes. One of the most important features of this study is to explore the simultaneous effect of annealing and particle loadings on the morphology and gas permeation properties of the prepared membranes. The membranes were characterized by Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM) analyses. Also, the CO2/N2 separation performance of the membranes was evaluated by single gas permeation measurements. The results showed that annealing causes a considerable improvement in the morphology of the CA and the related mixed matrix membranes. Additionally, more than a two-fold increase in CO2 permeability with no considerable decrease in CO2/N2 selectivity was achieved by a 20 wt.% NaY loading into the CA membrane. The results of investigating the effect of pressure (4–22 bars) on CO2 permeability showed a reduction in the CO2-induced plasticization of glassy CA with a significant shift in the plasticization pressure toward higher values. The introduction of NaY zeolite in the annealed CA membranes, shifted the plasticization pressure from 12.76 to 16.86 bars when the zeolite loading was changed from 0 to 25 wt.%.
47 citations
TL;DR: In this paper, the influence of low molecular weight polyethylene glycol (PEG 200) on physicochemical, morphological, and gas separation properties of Matrimid®5218 as a novel polymer blend was investigated.
Abstract: Polyethylene glycols have received worldwide attention as a highly permeable CO2-philic polymer in carbon dioxide separation applications. In this study, we investigated the influence of a low molecular weight polyethylene glycol (PEG 200) on physicochemical, morphological, and gas separation properties of Matrimid®5218 as a novel polymer blend. Both symmetric and asymmetric Matrimid flat sheet membranes with 0–20 wt.% PEG were prepared via a dense film-casting method. The miscibility of blends at low PEG concentrations (3–5 wt.%) was confirmed by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). Moreover, the blends were partially miscible at higher PEG concentrations (10–20 wt.%). Matrimid/PEG molecular interactions were further studied by FTIR and XRD analysis. SEM images indicated an impressive influence of PEG on the symmetric structure of Matrimid membrane. An asymmetric structure with a dense thin skin layer and a highly porous sub-layer was observed for the blends containing 10–20 wt.% PEG. The CO2 permeability and CO2/CH4 selectivity of the best-yield CO2-selective blend membrane (Matrimid/PEG (95:5)) incvreased about 25% (from 7.68 to 9.62 Barrer) and 15% (from 35 to 40) compared to pure Matrimid, respectively. Furthermore studying the plasticization pressures of the membranes revealed that the more PEG content in blend the less the plasticization pressure obtained. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
42 citations
TL;DR: In this paper, a microplasma reactor was used to decompose CO2 into carbon monoxide (CO) at normal atmosphere and room temperature, and a variety of parameters, such as feed flow rate, input power, frequency, discharge gap, and external electrode length were examined.
Abstract: The continually increasing use of fossil fuels throughout the world has caused carbon dioxide (CO2) concentration to grow rapidly in the atmosphere. Increasing CO2 emissions are the major cause of global warming, and a number of studies have been done to show the predicted effects of global warming. This paper reported a method of degradation of CO2 through dielectric barrier discharge (DBD) plasma; a microplasma reactor was used to decompose CO2 into carbon monoxide (CO) at normal atmosphere and room temperature. Gas chromatography was used to analyze the compositions of the outlet gases. No carbon deposits were found in this work. A variety of parameters, such as feed flow rate, input power, frequency, discharge gap, and external electrode length were investigated. The effects of these parameters on CO2 conversion were examined. At the same time, the effects of feed flow rate and input power on the energy efficiency were studied. The results indicated that a higher conversion of CO2 can be realized with a lower feed flow rate, a limited higher input power and a lower frequency. However, a higher feed flow rate and a lower input power were beneficial for energy utilization. The discharge gap had a little effect on the conversion of CO2 in microplasma reactor. In this work, the highest conversion of CO2 was 18.0%, and the highest energy efficiency was 3.8%. The DBD microplasma is a promising method for decomposing CO2.© 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
42 citations
TL;DR: In this paper, a non-isothermal injection of CO2 in deformable porous media considering the In Salah, Algeria, CO2 storage site was studied and it was shown that shear slip along preexisting fractures may take place in the cooled region, whereas tensile failure is less likely to occur.
Abstract: Thermo-mechanical effects are important in geologic carbon storage because CO2 will generally reach the storage formation colder than the rock, inducing thermal stresses. Capillary functions, i.e., retention and relative permeability curves, control the CO2 plume shape, which may affect overpressure and thus, caprock stability. To analyze these thermal and capillary effects, we numerically solve non-isothermal injection of CO2 in deformable porous media considering the In Salah, Algeria, CO2 storage site. We find that changes in the capillary functions have a negligible effect on overpressure and thus, caprock stability is not affected by capillary effects. However, we show that for the strike slip stress regime prevalent at In Salah, stability decreases in the lowest parts of the caprock during injection due to cooling-induced thermal stresses. Simulations show that shear slip along pre-existing fractures may take place in the cooled region, whereas tensile failure is less likely to occur. Indeed, only the injection zone and the lowest tens of meters of the 900-m-thick caprock at In Salah might be affected by cooling effects, which would thus not jeopardize the overall sealing capacity of the caprock. Furthermore, faults are likely to remain stable far away from the injection well because outside the cooled region the injection-induced stress changes are not sufficient to exceed the anticipated shear strength of minor faults. Nevertheless, we recommend that thermal effects should be considered in the site characterization and injection design of future CO2 injection sites to assess caprock stability and guarantee a permanent CO2 storage. (C) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
42 citations
TL;DR: In this article, the effect of the moisture of polyethylenimine (PEI) impregnated mesoporous precipitated silica used for CO2 adsorption on the heat capacity and the heat required to regenerate the adsorbent was investigated.
Abstract: In this study, we report the effect of the moisture of polyethylenimine (PEI) impregnated mesoporous precipitated silica used for CO2 adsorption on the heat capacity and the heat required to regenerate the adsorbent. The results indicate that the heat capacity of the absorbent increases as its moisture content increases. The increase in moisture results in the rise of the vaporization heat of water and the elevated heat capacity results in higher sensible heat. For these reasons, the total regeneration heat required for CO2 capture process increases significantly. The adsorbent has a maximum CO2 adsorption capacity at 75 °C. CO2 capture process using PEI impregnated mesoporous precipitated silica requires a minimum energy to regenerate the adsorbent; it reduces 46% of the energy compared to a process using an aqueous MEA 30 wt%, as the process operates at 75 °C.
38 citations
TL;DR: Based on the site-specific geology and the observational data, a numerical injection model was developed in order to understand the hydrodynamic behavior of CO2 in the subsurface for evaluating reservoir performance as mentioned in this paper.
Abstract: A carbon dioxide (CO2) capture and storage demonstration project was started in 2010 by injecting around 100 000 tonnes of super-critical CO2 per annum into a set of very low-permeability sandstone at depths of more than 1600 m in the northeastern Ordos Basin, China. Based on the site-specific geology and the observational data, a numerical injection model was developed in order to understand the hydrodynamic behavior of CO2 in the subsurface for evaluating reservoir performance. The results show that the model reasonably described the spreading of the CO2 plume. The Triassic Liujiagou sandstone aquifer is the most favorable storage formation for CO2 sequestration at the site of interest. After three years of injection of CO2, the maximum lateral migration distance of CO2 plume is about 550 m and the pressure build-up is about 13 MPa in the Liujiagou formation for the actual injection simulation. The major storage layer is at depths of 1690–1699 m, which contributes around 80% of injectivity of the entire reservoir system. The leakage of CO2 into the geological seals is negligible (<0.1%) over the entire simulation period. Regardless of the relatively good fit during the calibration period, the model overestimated the pressures associated with the injection thereafter. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
34 citations
TL;DR: In this article, the effect of adding relatively small quantities of Novozymes NS81239 (NCA) carbonic anhydrase enzyme on the absorption of CO2 into a 30 wt% potassium carbonate solution has been investigated.
Abstract: The effect of adding relatively small quantities of Novozymes NS81239 (NCA) carbonic anhydrase enzyme on the absorption of CO2 into a 30 wt% potassium carbonate solution has been investigated. Results demonstrated that at 40°C the addition of 2 μM NCA enhances the pseudo-first-order rate coefficient and thus the overall absorption process of CO2 into potassium carbonate solvents by around 30%. As the enzyme concentration is increased in the range of about 0 to 2 μM the enhancement increases according to a first order relationship, although further increasing the NCA concentration to 9 μM presented no greater catalytic effect than that from 2 μM. The rate coefficient for NCA catalyzed CO2 hydration measured in 30 wt% K2CO3 solution at 40°C in a wetted wall column is similar to that measured in dilute, neutral pH media at room temperature using stopped flow spectrophotometry. This work also demonstrates that, at a constant enzyme concentration, the overall absorption of CO2 into carbonate solvents increases with temperature from 40°C to 60°C, whereas above this range an increase in temperature proves to be counter-productive.
33 citations
TL;DR: In this article, the authors suggest that near-term investment could focus on implementing CO2 capture on facilities that produce high-value chemicals/products, more than coal-fired power plants.
Abstract: CO2 capture, utilization, and storage (CCUS) technology has yet to be widely deployed at a commercial scale despite multiple high-profile demonstration projects. We suggest that developing a large-scale, visible, and financially viable CCUS network could potentially overcome many barriers to deployment and jumpstart commercial-scale CCUS. To date, substantial effort has focused on technology development to reduce the costs of CO2 capture from coal-fired power plants. Here, we propose that near-term investment could focus on implementing CO2 capture on facilities that produce high-value chemicals/products. These facilities can absorb the expected impact of the marginal increase in the cost of production on the price of their product, due to the addition of CO2 capture, more than coal-fired power plants. A financially viable demonstration of a large-scale CCUS network requires offsetting the costs of CO2 capture by using the CO2 as an input to the production of market-viable products. We demonstrate this alternative development path with the example of an integrated CCUS system where CO2 is captured from ethylene producers and used for enhanced oil recovery in the US Gulf Coast region. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the effect of nanoparticles on CO2 absorption kinetics of amine-based solutions with additive of SiO2 and Al2O3 nanoparticles was investigated by wetted-wall column experiments.
Abstract: Nanoparticles suspended in solutions are considered to have the potential to enhance gas-liquid mass transfer and have been studied for gas separation. In order to reveal the mechanisms of kinetics enhancement, the diffusion and reaction process should be carefully examined. In this paper, CO2 absorption kinetics of amine-based solutions with additive of SiO2 and Al2O3 nanoparticles were investigated by wetted-wall column experiments. Measurements at different conditions, including solid loading, pressure, and solvent flow rate, show a significant enhancement on CO2 absorption kinetics. The experiment and model analysis indicate that the micro convective motion induced by particle Brownian movement plays a primary role in mass transfer enhancement. Three solutions, MEA, MDEA, and PZ which have different kinetics were selected to study the impact of nanoparticles on absorption kinetics of solutions with different reaction rate. It is interesting to find that the increased ratio of absorption kinetics by nanoparticle follows the same order with increased solvent reaction rate with CO2, which is PZ > MEA > MDEA. The wetted-wall kinetic model indicates that a diffusion controlled kinetics for PZ solution could result in much more significant kinetic enhancement with additives of nanoparticles. By operation conditions optimization, the liquid side mass transfer rate of MEA solution can be increased over 15%.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the authors examine contrasting metal mobilization behaviors at two field tests and in one laboratory study, to investigate whether the same mechanisms could explain metal releases in these different experiments, and show that fast Ca-driven cation exchange from calcite dissolution can explain the release of most major and trace metal cations at both sites, and their parallel concentration trends.
Abstract: The dissolution of CO2 in water leads to a pH decrease and a carbonate content increase in affected groundwater, which in turn can drive the mobilization of metals from sediments The mechanisms of metal release postulated in various field and laboratory studies often differ Drawing primarily on previously published results, we examine contrasting metal mobilization behaviors at two field tests and in one laboratory study, to investigate whether the same mechanisms could explain metal releases in these different experiments Numerical modeling of the two field tests reveals that fast Ca-driven cation exchange (from calcite dissolution) can explain the release of most major and trace metal cations at both sites, and their parallel concentration trends The dissolution of other minerals reacting more slowly (superimposed on cation exchange) also contributes to metal release over longer time frames, but can be masked by fast ambient groundwater velocities Therefore, the magnitude and extent of mobilization depends not only on metal-mineral associations and sediment pH buffering characteristics, but also on groundwater flow rates, thus on the residence time of CO2-impacted groundwater relative to the rates of metal-release reactions Sequential leaching laboratory tests modeled using the same metal-release concept as postulated from field experiments show that both field and laboratory data can be explained by the same processes The reversibility of metal release upon CO2 degassing by de-pressurization is also explored using simple geochemical models, and shows that the sequestration of metals by resorption and re-precipitation upon CO2 exsolution is quite plausible and may warrant further attention
TL;DR: In this paper, a solution of 8 molal PZ was recently evaluated at the Tarong CO2 capture pilot plant in Australia, and the results showed that regeneration energy requirements achieved with concentrated PZ were consistently lower than those achieved with 30 wt% monoethanolamine (MEA).
Abstract: Concentrated piperazine (PZ) is a promising new solvent under consideration for post-combustion capture (PCC) of CO2. A solution of 8 molal PZ was recently evaluated at the Tarong CO2 capture pilot plant in Australia. Initial operation involved evaluation of different operating conditions at the plant to determine the minimum energy conditions for this solvent. Comparison was made to results achieved previously at the same pilot plant with 30 wt% monoethanolamine (MEA). Regeneration energy requirements achieved with concentrated PZ were consistently lower than those achieved with MEA. The lowest regeneration energy for PZ at the pilot plant (2.9 MJ/kgCO2) was roughly 15% lower than the best result predicted for MEA. Inter-cooling located at the center of the absorber column was also evaluated for the concentrated PZ solvent. The benefit of inter-cooling was found to depend on the operating conditions of the plant, with operation at higher liquid-to-gas (L/G) ratios showing a more pronounced effect. For an L/G ratio of 3.3 kg/kg, inter-cooling was found to lower the regeneration energy required for PZ by approximately 10%.
TL;DR: In this paper, a hollow fiber Air Products PRISM and a spiral wound Dow Filmtec® NF3838/30FF membrane were separately trialed for membrane separation of CO2 from flue gas generated by a lignite-fired power station.
Abstract: Industrial trials of membrane separation of CO2 from flue gas generated by a lignite-fired power station are reported. A hollow fiber Air Products PRISM and a spiral wound Dow Filmtec® NF3838/30FF membrane were separately trialed. The CO2 permeance and selectivity through the PRISM membrane fell significantly in the initial hours of operation, reflecting competitive sorption effects and concentration polarisation. Alternatively, the wet flue gas enabled a facilitated transport mechanism to operate for the NF3838/30FF membrane and the CO2 permeance and selectivity increased significantly compared to the dry membrane. Standard correlations were able to simulate the pressure drops through the modules.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: Alvarez-Gutierrez et al. as discussed by the authors used activated carbons as potential adsorbents for CO2/CH4 separation, and showed that the effect of activation parameters on CH4 separation can be significant.
Abstract: This is the accepted version of the following article: Alvarez-Gutierrez, N., Victoria Gil, M., Rubiera, F. and Pevida, C. (2015), Cherry-stones-based activated carbons as potential adsorbents for CO2/CH4 separation: effect of the activation parameters. Greenhouse Gas Sci Technol, 5: 812–825. doi: 10.1002/ghg.1534, which has been published in final form at http://dx.doi.org/10.1002/ghg.1534
TL;DR: In this article, an experimental investigation of the effective parameters, including overburden pressure, ambient temperature, and CO2 impurities in the form of non-condensable and non-reactive CH4 and N2 gases on the capability of shale and anhydrite cores to preserve CO2 gas is conducted.
Abstract: Caprock integrity is a primary criterion for evaluating depleted oil and gas reservoirs for long-term safety of carbon dioxide geosequestration. The occurrence of capillary leakage is inevitable in caprock. This phenomenon occurs whenever the buoyancy pressure due to accumulated CO2 plumes dominates the capillary pressure of caprock, and thereby the plumes intrude into the pore throats. In this study, experimental investigation of the effective parameters, including overburden pressure, ambient temperature, and CO2 impurities in the form of non-condensable and non-reactive CH4 and N2 gases on the capability of shale and anhydrite cores to preserve CO2 gas is conducted. In this regard, capillary breakthrough pressure and CO2 gas effective permeability analysis were performed applying two distinct techniques, step by step and residual capillary pressure. Experiments were conducted at the temperatures of 35, 70, and 90 °C and overburden pressures in the range of 3500–5800 psi. Two main seal rocks, including shale and anhydrite core samples, from middle Asmari and Gachsaran formations of the Zagros Basin located in the southwest of Iran were used. Regarding the high capillary breakthrough pressure and low gas effective permeability after outbreak of the leakage, all three parameters have noticeable effects on capillary sealing efficiency of the caprocks. The results indicate that impurities such as CH4 and N2 have a significant effect on capillary breakthrough pressure of caprock and gas effective permeability. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the authors developed an analytical model to predict the amount of asphaltene deposition, rock dissolution, and their cementation, which is evaluated to determine the effect of cementation on reservoir permeability.
Abstract: Carbon dioxide (CO2) injection in depleted oil reservoirs is a potential means of reducing CO2 emissions. In this regard, CO2-related formation damages are considered key technical and economical issues. When CO2 is injected after water flooding, it can be stored by hydrodynamic trapping, dissolution, and mineral trapping. This process leads to the formation of carbonic acid, which may react and dissolve the carbonates. The precipitation of these carbonates can reduce oil productivity and CO2 injectivity. In this study, we develop an analytical model to predict the amount of asphaltene deposition, rock dissolution, and their cementation. Primarily, we develop an analytical model that treats the asphaltene deposition and carbonate dissolution in radial geometry. Then, this model predicts cementation, which is evaluated to determine the effect of cementation on reservoir permeability. Finally the developed model is compared with experimental data and determined the factors affecting the cementation. From analyses of different cases, cementation is a few percent but its percentage increases with time. The results presented in this study indicate that the amount of cementation depends on asphaltene percentage, flow rate, flow period, and reservoir depth. The model assumes constant reservoir temperature and no capillary and gravity forces. However, these forces might increase asphaltene-carbonate cementation in the reservoir.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: A summary and a brief description of the recent activities being carried out by these sectors, aiming to develop and promote CCS in Brazil can be found in this paper, where the authors highlight the importance of pre-salt reservoirs in the development of CCS.
Abstract: Brazil is recognized for possessing a low carbon-intensive energy matrix, with most of its power being generated from hydroelectricity. Its greenhouse gas emissions profile is dominated by deforestation and land-use change. Despite this characteristic, the country has been committed to the development of carbon capture and geological storage (CCS) research since this technology started to be recognized as a relevant solution for greenhouse gas emission reductions. This development has gained attention recently owing to the beginning of the production of pre-salt reservoirs, which may contain significant amounts of CO2 in the produced fluids. The work has been carried out mostly through the efforts of the academia and industrial enterprises. This paper presents a summary and a brief description of the recent activities being carried out by these sectors, aiming to develop and promote CCS in Brazil.
TL;DR: In this article, the authors investigated 0.3 M ammonia solutions on different operation factors such as feed flow rate, feed temperature, pressure in the permeate side, and CO2 loading.
Abstract: Aiming to solve the problem of high ammonia loss during ammonia-based CO2 chemical absorption process, an ammonia wash system was recommended to be added after the absorber column. Hence, we need to deal with a lot of wash water. Recently, we proposed a vacuum membrane distillation (VMD) system to regenerate ammonia from ammonia wash water. The stripping gaseous ammonia can be used for producing a high-concentration ammonia solution for solvent make-up in the CO2 capture system, and the wash water after distillation can be reused. In this work, we investigated 0.3 M ammonia solutions on different operation factors such as feed flow rate, feed temperature, pressure in the permeate side, and CO2 loading. The experimental results show that both temperature and pressure in the permeate side have significant influences on the ammonia stripping process. Increasing feed temperature and reducing pressure in the permeate side will not only improve ammonia removal efficiency, but also enhance total transmembrane flux and overall mass transfer coefficient. The increase of feed flow rate can improve the total transmembrane flux, but will lower the ammonia removal efficiency. The increase of CO2 loading in the feed ammonia solution will decrease the ammonia removal rate. Furthermore, we investigated a continuous circulation experiment and found that the ammonia removal efficiency largely depended on the removal time. The removal efficiency can be up to 95.6% with a 120 min continuous circulation time. We think this VMD system has the potential to recover ammonia and solve the solvent loss problem. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the authors evaluate the environmental performance of two similarly structured combined-cycle power plants with pre-combustion capture and find that the two plants result in similar impacts, decreasing the contribution to global warming of conventional operation but, at the same time, increasing other impacts, such as ozone layer depletion and photochemical oxidant formation.
Abstract: CO2 capture and storage involves technologies that separate, capture, and store CO2 from large facilities, such as fossil fuel power plants. Although it is a promising measure to meet environmental standards on carbon pollution, proposed technologies in power plants are energy demanding and decrease the energy generated per unit of input fuel when compared to business-as-usual scenarios. In this paper, we evaluate the environmental performance of two similarly structured combined-cycle power plants with pre-combustion capture. The first power plant performs methane steam reforming in an autothermal reformer, while the second plant uses a reactor that includes a hydrogen-separating membrane. The two plants are compared both to one another and to a business-as-usual scenario using six environmental impact potentials (abiotic depletion, global warming, ozone layer depletion, photochemical oxidant formation, acidification, and eutrophication). The goal is to pinpoint environmental weaknesses and strengths of the two capture technologies. We find that the two plants result in similar impacts, decreasing the contribution to global warming of conventional operation but, at the same time, increasing other impacts, such as ozone layer depletion and photochemical oxidant formation. Additionally, the two capture plants result in higher cumulative non-renewable and total energy demands, as well as in lower life-cycle energy balances and efficiencies. The most direct measure to decrease the environmental impacts of the examined techniques would be to increase their efficiency, by decreasing the requirements of the processes in natural and energy resources.© 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: Wang et al. as discussed by the authors used 798 mines as samples, aiming to find a function of the relative gas emission rate and coal production, and designed a coefficient-intensity factor methodology integrated with IPCC methodology, to make a contribution to increase its applicability to regional circumstances.
Abstract: Coal mine methane (CMM) is an important component of greenhouse gas (GHG) control, clean energy, and coal mining safety. Because of the complicated geological conditions and non-linear characteristics of CMM emissions, the Intergovernmental Panel on Climate Change (IPCC) calculation methodology of CMM emissions is based on a large emission factor range (10–25 m3/t), limiting the accuracy of the CMM emissions calculation. This paper studies CMM emission characteristics, and designs a coefficient-intensity factor methodology integrated with IPCC methodology, to make a contribution to increase its applicability to regional circumstances. Using China as a case study, this paper uses 798 mines as samples, aiming to find a function of the relative gas emission rate and coal production. Through the calculation of the classification outflow coefficient and the regional emission intensity factor, the national emission intensity factor is about 9.176, which is lower than the minimum of IPCC emission factors for underground mining. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this article, Li5AlO4 was synthesized and mixed with either potassium carbonate or sodium carbonate, and the results revealed that the weight gained on α−Li5alO4 mixed with K- or Na-carbonates was attributed to the formation of the eutectic phases.
Abstract: Lithium aluminate (α−Li5AlO4) was synthesized and mixed with potassium carbonate or sodium carbonate. The addition of these alkaline carbonates was produced during or after the synthesis process. The CO2 chemisorption was evaluated using dynamic, isothermal, and cyclic thermogravimetric analyses. The presence of the K or Na in α−Li5AlO4 changes the sorption properties in a wide temperature range. K- and Na-Li5AlO4 samples, when the alkaline carbonates were added 10 wt% presented better CO2 capture properties, capturing 37−39 wt% at 660 °C and ∼50 wt% at 710 °C, for doped samples prepared mechanically or synthetically, respectively. The results revealed that the weight gained on α−Li5AlO4 mixed with K- or Na-carbonates was attributed to the formation of the eutectic phases. These materials would be suitable for CO2 capture over a wide temperature range depending on the application process. Nevertheless, the cyclic experiments showed important variations in their respective efficiencies, depending on the temperature. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the authors investigated the effect of total pressure on CO2 absorption and ammonia vaporization in ammonia solutions on a wetted-wall column and found that the elevated pressure absorption process was an effective way to increase CO 2 absorption rate and suppress ammonia vaporisation at the same time.
Abstract: The low CO2 absorption rate and high ammonia volatile loss rate are two major issues for the ammonia-based CO2 capture technology. In this work, we investigated the effect of total pressure on CO2 absorption and ammonia vaporization in ammonia solutions on a wetted-wall column. We found that the elevated pressure absorption process was an effective way to increase CO2 absorption rate and suppress ammonia vaporization at the same time. We also studied the mass transfer mechanism at elevated pressure and found the overall mass transfer coefficients of CO2 absorption in both ammonia and MEA solutions at elevated pressures were lower than that under atmospheric pressure. The overall mass transfer coefficients of CO2 absorption in 3 M NH3 (298 K) at 1, 1.5, 2, 2.5 bar were 0.723 × 10−6, 0.652 × 10−6, 0.591 × 10−6, 0.555 × 10−6 mol/(s m2 Pa) and the corresponding gas side mass transfer coefficients were 13.8 × 10−6, 4.52 × 10−6, 2.61 × 10−6, 2.03 × 10−6 mol/(s m2 Pa), respectively. We also found the gas side mass transfer coefficient in the wetted-wall column was not only dependent on the hydrodynamic conditions of the column but also influenced by the total pressure. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, the authors applied life cycle assessment (LCA) techniques to evaluate the processes controling the environmental impacts of anaerobic digestion (AD) pathways on a modeled dairy farm setting representative of Wisconsin.
Abstract: This study applies life cycle assessment (LCA) techniques to evaluate the processes controling the environmental impacts of anaerobic digestion (AD) pathways on a modeled dairy farm setting representative of Wisconsin. Seven electricity-producing AD pathways are compared against a base-case (BC) pathway to understand the effect of management practices, co-digestion strategies, and energy conversion processes on greenhouse gas (GHG) emissions, ammonia (NH3) emissions, depletion of fossil fuels (DFF), and nutrient balances. The pathway selected has a substantial influence on the estimates of environmental impacts. GHG emissions range from 178 to 267 kg CO2-eq GJ−1, NH3 emissions range from 11 to 18 kg GJ−1, DFF range from 176 to 327 MJ GJ−1, and N availability ranges from 7 to 15 kg GJ−1 of produced energy. The results of this paper show that the environmental benefits and concerns of anaerobic digestion systems can be further improved with the adoption of management practices on-farm. Injection of digestate during land application is an effective management practice to reduce NH3 emissions, which at the same time increases N availability and reduces GHG emissions and DFF given that the manufacturing of purchased fertilizers is fossil energy intensive. Co-digesting manure with corn stover and switchgrass increases energy production. Recovering heat has proven to be an easy to adopt strategy that improves all sustainability indicators without implementing major operational changes. Finally, 100 kg CO2-eq GJ−1, 4.2 kg NH3 GJ−1 and 566 MJ GJ−1 are determined for GHG emissions, NH3 emissions and DFF respectively for a compressed biogas pathway. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this article, Geological storage in sedimentary basins is considered a viable technology in mitigating atmospheric CO2 emissions, and alternating high and low permeability strata are common in these basins.
Abstract: Geological storage in sedimentary basins is considered a viable technology in mitigating atmospheric CO2 emissions. Alternating high and low permeability strata are common in these basins. The dist ...
TL;DR: In this paper, the greenhouse carbon dioxide emissions (CO 2 ) released from the fossil fuels (i.e., oil and natural gas) used in the country for energy production purposes was computed by using the Intergovernmental Panel on Climate Change (IPCC) reference approach for National Greenhouse Gas Inventories.
Abstract: Worldwide, many countries are being affected by greenhouse gas (GHG) emissions. The Sultanate of Oman is no exception. In Oman, both oil- and natural-gas-related activities have the most important shares of the nation's Gross Domestic Product (GDP). Hence, they are expected to be the primary cause of GHG emissions within the country. In this study, the greenhouse carbon dioxide emissions (CO 2 ) released from the fossil fuels (i.e., oil and natural gas) used in the country for energy production purposes was computed by using the Intergovernmental Panel on Climate Change (IPCC) reference approach for National Greenhouse Gas Inventories. The objective was to develop the CO 2 emissions for Oman over the last 40 years starting from year 1972. The obtained results indicated that Oman has a growth in its CO 2 GHG emissions. This study is very important and essential, as it will assist Oman to monitor its progress in reducing CO 2 emissions. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: Cozier as discussed by the authors takes a look how the major players have positioned themselves to influence and bring about an agreement and how carbon capture and storage (CCS) is very much part of the toolkit required to help keep greenhouses GHGs in check.
Abstract: The United Nations Conference of Parties 21 (UN COP21) Climate Change Conference, which runs from 30 November to 11 December in Paris, France, has set out to reach a binding agreement to cut emissions of greenhouse gases (GHGs) and to set goals for economic development and social and environmental issues. Muriel Cozier takes a look how the major players have positioned themselves to influence and bring about an agreement and how carbon capture and storage (CCS) is very much part of the toolkit required to help keep greenhouses GHGs in check. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
TL;DR: In this paper, novel membranes were prepared from blending the ethylene vinyl acetate (EVA) and poly(ethylene glycol) (PEG) with molecular weights of 200, 1000, and 1500, and considered for CO2/N2 separation over the feed pressure of range 2-8 bar.
Abstract: In this paper, novel membranes were prepared from blending the ethylene vinyl acetate (EVA), containing 28 wt.% of vinyl acetate, and poly(ethylene glycol) (PEG) (0–20 wt.%) with molecular weights of 200, 1000, and 1500, and considered for CO2/N2 separation over the feed pressure of range 2–8 bar. Physical properties and the morphology of the membranes were evaluated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses in order to justify the gas permeation and separation performance of the membranes. The results showed that CO2 permeability increases by increasing the PEG content of the blend membranes. However, increasing PEG loading enhanced CO2/N2 selectivity just for the blends containing up to 10 wt.% of PEG and it decreased at higher PEG loadings. The PEG with a molecular weight of 200 showed a more efficient gas separation performance due to its effective role in providing amorphous regions in the blends. Furthermore, higher CO2 permeabilities were obtained at higher feed pressures. The selectivity increased by increasing the feed pressure for neat EVA, EVA/5 wt.% PEG and EVA/10 wt.% PEG membranes, but it had no significant effect on the selectivity of the samples with 15 and 20 wt.% of PEG.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd