Adsorption of pure carbon dioxide and methane on dry coal from the sulcis coal province (SW Sardinia, Italy) (original) (raw)
Related papers
Sequestration of Carbon Dioxide in Coal with Enhanced Coalbed Methane RecoveryA Review †
Energy & Fuels, 2005
This article reviews the storage of captured CO 2 in coal seams. Other geologic formations, such as depleted petroleum reservoirs, deep saline aquifers and others have received considerable attention as sites for sequestering CO 2 . This review focuses on geologic sequestration of CO 2 in unmineable coalbeds as the geologic host. Key issues for geologic sequestration include potential storage capacity, the storage integrity of the geologic host, and the chemical and physical processes initiated by the deep underground injection of CO 2 . The review topics include (i) the estimated CO 2 storage capacity of coal, along with the estimated amount and composition of coalbed gas; (ii) an evaluation of the coal seam properties relevant to CO 2 sequestration, such as density, surface area, porosity, diffusion, permeability, transport, rank, adsorption/desorption, shrinkage/swelling, and thermochemical reactions; and (iii) a treatment of how coalbed methane (CBM) recovery and CO 2 -enhanced coalbed methane (ECBM) recovery are performed (in addition, the use of adsorption/ desorption isotherms, injection well characterization, and gas injection are described, as well as reservoir screening criteria and field tests operating in the United States and abroad); (iv) leak detection using direct measurements, chemical tracers, and seismic monitoring; (v) economic considerations using CO 2 injection, flue gas injection, and predictive tools for CO 2 capture/ sequestration decisions; (vi) environmental safety and health (ES&H) aspects of CO 2 -enhanced coalbed methane/sequestration, hydrodynamic flow through the coal seam, accurate gas inventory, ES&H aspects of produced water and practices relative to ECBM recovery/sequestration; (vii) an initial set of working hypotheses concerning the chemical, physical, and thermodynamic events initiated when CO 2 is injected into a coalbed; and (viii) a discussion of gaps in our knowledge base that will require further research and development. Further development is clearly required to improve the technology and economics while decreasing the risks and hazards of sequestration technology. These concerns include leakage to the surface, induced seismic activity, and long-term monitoring to verify the storage integrity. However, these concerns should not overshadow the major advances of an emerging greenhouse gas control technology that are reviewed in this paper.
CO2-ECBM and CO2 Sequestration in Polish Coal Seam – Experimental Study
Journal of Sustainable Mining, 2014
Methane recovery is interesting not only because of its clean combustion; it is also beneficial for the environment because of the reduction of the amount of methane emitted into the atmosphere, which is important because of methane's significant impact on the greenhouse effect. However, desorption of methane is a slow process, significantly dependent on the coalification of coal, its porosity and petrographic composition. Injection of carbon dioxide into the coal bed under sufficient pressure might be a factor in stimulating the efficiency of this process, asbecause of preferential sorptioncarbon dioxide displaces methane molecules previously absorbed in the coal matrix. Methods The measurements were made for Polish low-rank coal used for the analysis of methane recovery from Polish coal mines. Coal samples were collected from sites used for geological, sorption and petrographic research, as well as for the assessment of the reservoir's genetic origin CH 4 content. Experimental studies of sorption were performed with the use of the volumetric method at a lower and higher gas pressure. Results The methane isothermes show more than double the reduction of adsorption along with increasing temperature. The most significant changes of sorption capacity due to temperature variations can be seen when observing the difference in the course of the hysteresis of sorption/desorption of the gas as a function of temperature. In cases where there is a temperature of 323 K, a temperature hysteresis loop might indicate larger quantities of methane trapped in the porous structure of coal. In cases of carbon dioxide as sorbate, a similar shape of sorption isotherms occurred at both temperatures, while the temperature increase caused approximately double the reduction of sorption capacity. Also the isotherm's shape is similar for both temperatures of measurement, indicating no effect of temperature on the amount of gas within the structure of the tested coal. High-pressure isotherms of CO 2 and CH 4 are confirmed in the literature, proving that carbon dioxide is the gas that allows the best penetration of the internal structure of bituminous coal. The critical temperature of CO 2 (304.5 K) is so high, that sorption measurements can be performed at room temperatures (293, 298 K), where activated diffusion is relatively fast. Practical implications Understanding the sorption of gases is the primary issue, related to the exploitation of coal seams, when explaining the mechanism of gas deposition in coal seams and its relationship with outbursts of rocks and gases in mines. Originality/ value The results indicate successful sorption of carbon dioxide in each experiment. This provides the rationale to study the application of the coal tested to obtain methane genetic origin genetic methane with the use of the CO 2 injection.
Mechanisms in CO2-enhanced coalbed methane recovery process
Advances in geo-energy research, 2022
Injection of CO 2 and subsequent desorption of CH 4 is considered to be the most efficient enhanced coalbed methane (ECBM) recovery technique to date. Meanwhile, CO 2-ECBM is an excellent option for CO 2 geo-sequestration for an extended period. Despite ongoing research efforts and several field applications of this technology, the mechanisms of the process have yet to be fully understood. The coalbed heterogeneity, the fluid interactions with coal, the CO 2 induced swelling, and the continuous pressure and composition changes require outright insights for optimal application of the technique. Furthermore, intermolecular interactions of CO 2 and CH 4 , their competitive adsorption on the dry/wet coal surface, and the dispersion and advection processes play an important role in defining the CO 2-ECBM recovery process. An attempt has been made here to understand the key mechanisms of CO 2-ECBM recovery in coalfields, particularly the adsorption of CO 2 in the supercritical state at the recommended sequestration depth.
Study on CO 2 Sorption Capacity of Coal – An Experimental Approach
In the present situation of global warming, the percentage of í µí° ¶í µí± 2 in atmospheric air is increasing very rapidly, which will create major problem for the future generation. Storage of í µí° ¶í µí± 2 is gaining widespread interest as a potential method of controlling greenhouse gas emissions as suggested by Intergovernmental Panel on Climate Change (IPCC). This study includes methane desorption mechanism from coal bed, and suggests that the desorbed methane can be used as a pure fuel for many purposes. It is generally acknowledged that coal beds are an important rock medium with regard to their capacity to act as a reservoir for í µí° ¶í µí± 2 gas. In this paper, í µí° ¶í µí± 2 sorption capacity of coal under different temperatures has been investigated by experimental approach and also explains the effect of cracks on coal surface in its sorption capacity. As temperature and pressure increases, with the depth of seam from surface level, the mathematical relation derived from this experiment will be helpful in determination of total amount of í µí° ¶í µí± 2 that can be stored in a coal seam at various reservoir temperature. The results will be helpful to use enhanced production of methane as additional benefit and also to use coal seam as a permanent sink for anthropogenic í µí° ¶í µí± 2 emission.
Environmental Earth Sciences, 2013
The storage of CO 2 in unused coal mines is a viable option for reducing emissions of CO 2 , whose accumulation in the atmosphere is one of the main contributors to global warming. Understanding CO 2 behaviour and storage capacity of the coal is an important first step before injecting the CO 2. We used experimental equipment to extract coal from a mine and to obtain a representative sample of both its internal structure (in terms of cleats, macropores, mesopores and micropores) and occluded gases. Storage capacity was studied in terms of variations in gas pressure. The adsorption isotherm was experimentally obtained applying a procedure specifically designed to avoid altering the coal. An unused coal bed was selected to determine how much CO 2 it could adsorb and to study the feasibility of storing power plant CO 2 in this kind of mine.
The injection of carbon dioxide into coalbeds to increase methane recovery is an emerging technology which was tested in various pilot installations. Carbon dioxide stored in coalbeds is usually in supercritical state and therefore investigation of supercritical adsorption of this gas on coal is a subject of various studies. In the paper impact of three equations of state i.e. Peng Robinson (PR), Soave-Redlich-Kwong (SRK) and the most accurate Span-Wagner, as a reference, on the calculation of sorption capacity was investigated. Langmuir parameters were calculated on the basis of experimental results of CO 2 volumetric sorption by a Selar Cornish coal sample. It is concluded that the use of cubic equation of state (PR and SRK) for the calculation of supercritical CO 2 sorption on coal gives unreliable results by lowering apparent absolute adsorption in the lower pressure range (< 9 MPa) and unrealistically increasing it at higher pressures.
CO2 adsorption the numerical simulations and the controlling factors to low rank coal
IOP Conference Series: Earth and Environmental Science, 2018
Carbon Capture Sequestration (CCS) in unmineable coal seams questionably gives benefits for the commercial success through potential release of additional methane during the injection of CO2 adsorbs into the coal seams, the process known as enhanced coalbed methane (ECBM) recovery. However, a significant concern lies in the loss of injectivity due to reduction in permeability by coal matrix swelling occurences with CO2 adsorption although this effect can be partially be offset with 'huff and puff' scheme of cyclic CO2 injection followed by extraction of the released methane. The paper discusses the results of a numerical simulation study carried out with GEM compositional reservoir simulator to evaluate the effects of uncertainties in various reservoir parameters on the overall volume of CO2 storage and additional methane recovery of low rank coalfield. A 12-15m thick seam at shallow depth, 50-75 m was considered for fluid flow simulation study. While some information on the reservoir setting was obtained through literature and personal communication with the CBM operators, the rest of the information was derived through laboratory studies. The reservoir parameters considered for the study are injection pressure, adsorption capacity, cleat permeability and porosity, and initial gas saturation. A 100-acre drainage area with 5-spot vertical well pattern was considered with one central injector and four producers on four corners of the study area. The maximum allowable injection pressure was estimated to be 7500 kPa at the reservoir setting. The injection pressure was varied from 1000 kPa to 7500 kPa in the simulation .A number of adsorption isotherms were established in the laboratory. The variations in the adsorption parameters observed through the isotherms were considered as uncertainty in the storage capacities. Significant variations were observed due to the variation in adsorption isotherms both for CO2 storage and additional methane recovery. Fracture permeability was varied from 3 md to 200 md, which is the range of permeability observed in the coalfield is around 100-200 mD. The results of simulation indicate a strong influence of porosity on the CO2 storage and ECBM recovery. Fluid flow simulation study shows that variation in sorption time has no significant effect for a low permeability situation while some marginal effect in high permeability situation. Cleat porosity was varied from 1 % to 10 %. Within this range of porosities, enhanced methane recovery varied from 1 % to 10 % relative to the primary recovery but the volume of stored CO2 did not vary significantly. Lastly, the pore pressure, adsorption and gas saturation of CO2 sequestered volume and additional methane recovery were found to increase substantially.
Journal of Geochemical Exploration, 2003
During recent years, extensive studies have been undertaken at RWTH Aachen to assess the gas adsorption capacities of coals of different rank with respect to CH4, CO 2 and their mixtures [e.g. Int. Excess sorption isotherms of carbon dioxide recorded at 40, 60 and 80 °C on dry and moisture-equilibrated Carboniferous coals from the Netherlands exhibited distinct minima and even negative values in the 8-12 MPa interval. These anomalies are indicative of a strong volumetric effect. Evaluation of the experimental results in terms of absolute sorption assuming a range of different densities for the adsorbed phase could not eliminate the observed anomalies. In consequence, substantial swelling (up to 20%) of the (powdered) coal samples must be invoked to account for the observed phenomena. This interpretation is supported by the results of field tests in Alberta, Canada [Proceedings JCOAL Workshop: Present Status and Perspective of CO2 Sequestration in Coal Seams, Tokyo, Japan, (5 September 2002) 59 66], which resulted in a significant reduction in coal-seam permeability upon CO2 injection.
Methane and Carbon Dioxide Sorption and Transport Rates in Coal at In-situ Conditions
Energy Procedia, 2009
Geologic sequestration of carbon dioxide is an option for the mitigation of industrial emissions. However, considerable effort remains to shift this technology from its current status as potential solution to a safe, effective and trusted foundation to the global energy system. Characterization of gas movement and sorption capacity of coal at in-situ conditions is required. Using the volumetric method, measurements of CH 4 and CO 2 sorption and diffusion in coal have been made on powder and non-powder confined coal. Results obtained, emphasized that the sorption capacity and the kinetics of gas in coal are both influenced by the stress state of the sample. The application of 6.9 MPa confining stress contributed to about 30% and 80% of sorption capacity reduction for CO 2 and CH 4 respectively. The sorption and diffusion of CO 2 in confined coal follow two distinct rates described with diffusion coefficients of 2.3 x 10-6 m 2 /s and 9.4 x 10-12 m 2 /s respectively. In contrast, the flow of methane is characterized by a continuous process with a diffusion coefficient of 3.8 x 10-7 m 2 /s. These observations confirms the complex interaction of CO 2 with the coal structure and stressed that CH 4 and CO 2 sorption and transport in coal should be characterized differently, specifically when dealing with non-powder confined samples. Consequently, the use of information collected on pulverized coal samples for the simulation and prediction of long term underground sequestration and enhanced coalbed methane is not justified.