Net Coal Research Articles

Analysis and optimization of a coal-fired power plant under a proposed flue gas recirculation mode

This study mainly investigated the influence of flue gas recirculation (FGR) on reheat steam temperature, boiler efficiency, and thermal efficiency in a proposed FGR scheme. The main parameters of the boiler are calculated under different modes on the basis of a 600MW coal-fired boiler. Optimization is conducted, and the optimum recirculation rate and coal input are determined. Results from case study showed that under the same recirculation rate, the reheat temperature increases higher and the net coal consumption decreases more in the improved recirculation system than those in the traditional recirculation system. The key parameters, such as the FGR rate and coal feed rate are optimized. Under optimum recirculation rate and coal input conditions, the net coal consumption rate can be reduced by 2.35–2.60g/(kWh) compared with that obtained with the use of a conventional recirculation system. This net coal consumption rate can be reduced by 3.50–5.11g/(kWh) compared with that obtained without gas recirculation system. For a better operation, lower recirculation rate and relative higher coal input are recommended under high-load conditions, whereas higher recirculation rate and relative lower coal input are appropriate for low-load conditions.

Peak Gas Production Analysis and Influencing Factors Study of Coal Bed Methane Well

The value of peak gas production and the time when it reaches are two important marks for coal bed methane (CBM) well’s gas production curve. This paper takes M CBM gas field of A country’s B basin as actual production instance. Firstly, based on the CBM producing mechanism, the existence reason of peak gas rate is analyzed; secondly, the influencing factors of the value of peak gas production and the time when it reaches is studied by numerical simulation method. And sensitivity order of the influencing factors is obtained. The study results indicate that: the value of peak gas production has positive correlation with properties: permeability, gas content, coal bed net pay and gas saturation; while negative correlation with desorption time and cleat porosity. And the strong to weak intensity of sensitivity is permeability, gas content, desorption time, net coal bed pay, cleat porosity, gas saturation. The time when peak gas production reaches is markedly influenced by the value desorption time and cleat porosity, the smaller of the two parameters, the shorter of the time when peak gas production reaches.

China׳s energy security: Oil and gas

China is currently the largest energy consuming country in the world. Until the early 1990s, China had long been a net energy exporter. The country became a net oil importer in 1993, the first time since the 1960s. For China, energy security first means oil supply security. China turned into a net natural gas importer in 2007 and then a net coal importer in 2009. In other words, China is now a net importer of all three types of fossil energy—oil, natural gas, and coal.In the context of rising oil imports and implementation of China׳s 12th Five-Year Program from 2011 to 2015, this paper examines China׳s energy security strategies with a focus on three leading elements, namely overseas oil investment, strategic petroleum reserves (SPR)and unconventional gas development. Our findings suggest that the Chinese government has promoted overseas investment strongly; its SPR program has been established though the progress for Phase II has been slower than expected and the government intends to boost the unconventional gas sector development. However, the challenges are enormous as well. As for future research, other elements for each dimension of energy security should be reviewed to reach a comprehensive conclusion about how well China has done and what steps are needed to move forward.

Sensitivity Analysis and Optimization of a Coal-fired Power Plant in Different Modes of Flue Gas Recirculation

In a coal-fired power plant with flue gas recirculation, recirculation rate and coal input have a great effect on the performance of the power plant. In this paper, a 600 MW coal-fired boiler is taken as base case, the main parameters of the boiler are calculated at different recirculation rates and coal input conditions, an optimization is carried out and the optimum recirculation rate and coal input are reported. The results show that under optimum recirculation rate and coal input conditions, the net coal consumption rate can be reduced by 3.5g/(kW·h) at 575MW load; while it is 4.36g/(kW·h) and 5.11g/(kW·h), respectively, at 450MW load and 300MW load. Compared to the conventional flue gas recirculation system, the net coal consumption rate can be reduced by 2.31 g/(kW·h), 2.42 g/(kW·h) and 2.41 g/(kW·h), respectively, at 575MW, 450MW and 300MW load.

Life cycle assessment of sewage sludge co-incineration in a coal-based power station

A life cycle assessment was conducted to evaluate the environmental and economic effects of sewage sludge co-incineration in a coal-fired power plant. The general approach employed by a coal-fired power plant was also assessed as control. Sewage sludge co-incineration technology causes greater environmental burden than does coal-based energy production technology because of the additional electricity consumption and wastewater treatment required for the pretreatment of sewage sludge, direct emissions from sludge incineration, and incinerated ash disposal processes. However, sewage sludge co-incineration presents higher economic benefits because of electricity subsidies and the income generating potential of sludge. Environmental assessment results indicate that sewage sludge co-incineration is unsuitable for mitigating the increasing pressure brought on by sewage sludge pollution. Reducing the overall environmental effect of sludge co-incineration power stations necessitates increasing net coal consumption efficiency, incinerated ash reuse rate, dedust system efficiency, and sludge water content rate.

Influences of Clean Syngas Preheating Temperature on IGCC Power Plant Performances

400 MW IGCC power plants were modeled by using commercial software GT PRO. The high pressure unsaturated water extracted from heat recovery steam generator (HRSG) was used to heat clean syngas to various temperatures. The influences of clean syngas preheating temperature on plant performances were investigated. Results showed that net power output and coal consumption both reduced with the increase of syngas preheating temperature, and coal consumption reduced to a larger extent. Moreover, when syngas preheating temperature increased, the net electric efficiency increased and the net heat rate decreased gradually. It was concluded that preheating clean syngas in a reasonable way was beneficial to improve the performances of IGCC power plant.

Environmental impact assessment of three coal-based electricity generation scenarios in China

A life cycle assessment was conducted out to estimate the environmental impact of three coal-based electricity generation scenarios commonly used or encouraged in China, namely, sub-critical technology (300 MW), supercritical technology (600 MW), and ultra-supercritical technology (1000 MW). Compared with other scenarios, the ultra-supercritical technology accounted for significantly environmental benefits in most categories, except in the natural land occupation category because of the landfill disposal of coal ash. Optimizing net coal consumption efficiency, reusing coal ash as building material, increasing desulfurization and denitrization system efficiency, and decreasing the road transport distance from coal buyer to supplier are key factors in reducing the overall environmental impact of electricity generation.

The Walloon coal seam gas play, Surat Basin, Queensland

Extensive drilling of the Walloon Subgroup for coal seam gas (CSG) during the last decade has revealed a world-class CSG play on the northern flank of the Surat Basin. Resources discovered in the Walloon Subgroup exceed 30 TCF; this gas now underpins four CSG-to-liquefied natural gas (LNG) projects. Results to date have revealed the highly heterogeneous nature of the Walloon Subgroup and its associated coal properties. The Walloon Subgroup is typically 350 m thick and contains an average of 30 m of net coal that is interbedded with a range of clay-rich, fluvio-lacustrine lithologies. The most prospective area of the play occurs down-dip and adjacent to the Walloon subcrop edge, where high permeability exists combined with a thick section of net pay. Coals in the Walloon Subgroup are low rank (0.35–0.65% Ro) with gas contents ranging between 1–15 m3/tonne (dry ash-free). Average coal ply thickness is 30 cm, making correlation and prediction of reservoir properties difficult. Reservoir properties—including permeability, gas content and saturation—differ as a result of compositional variability of the coal seams and also the tectonic history. Mapping of sparse 2D seismic data has highlighted the distribution of major structural features throughout the basin. Coal fracture permeability ranges from less than 0.1 mD to more than 2,000 mD, and mapping has identified areas where permeability appears to be enhanced on structures that have undergone mid Cretaceous–Eocene deformation.

Evaluating Hydraulic-Fracture Effectiveness in a Coal-Seam-Gas Reservoir From Surface Tiltmeter and Microseismic Monitoring

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 133063, ’Evaluating Hydraulic-Fracture Effectiveness in a Coal-Seam-Gas Reservoir From Surface Tiltmeter and Microseismic Monitoring,’ by Raymond L. Johnson Jr., SPE, and Michael P. Scott, SPE, QGC; R.G. Jeffrey, SPE, and Zuorong Chen, SPE, CSIRO Earth Science and Resource Engineering; Les Bennett SPE, and Craig Vandenborn, SPE, Schlumberger; and Sergei Tcherkashnev, ASTO Geophysical Consulting, prepared for the 2010 SPE Annual Technical Conference and Exhibition, Florence, Italy, 19-22 September. The paper has not been peer reviewed. In developing coalbed-methane or coal-seam-gas (CSG) fields or reservoirs, the effects of many parameters are important in understanding the success or potential improvement of hydraulic-fracturing treatments. Estimating fracture geometry relative to reservoir architecture is critical in understanding production variability. An outline for steps used to plan the monitoring program is presented along with a description of how geological data were integrated to better understand the results observed during the treatments. A logical framework was developed to evaluate and integrate these technologies for use in future CSG-well stimulation. Introduction The wells in this study are in the Walloon coal measures of the Surat basin of eastern Queensland, Australia. The Walloon subgroup (WSG) is Middle Jurassic, comprising fluvial deposition dominated by definable transgressive events of peat-swamp deposition. It can be divided further into the Juandah and Taroom coal measures, which comprise 10 regionally correlatable coal packages with interbedded sandstone, silt-stone, and carbonaceous-shale intervals. Typically, the WSG is 1,000 to 1,200 ft thick, with net coal thickness ranging from 65 to 120 ft. There can be more than 50 plies of coal throughout these 10 coal packages, with average ply thickness of 1 to 2 ft and the maximum typically between 7 and 10 ft. Generally, hydraulic fracturing resulted in low-productivity wells in the early pilot areas of the Surat basin and resulted in wellbore failures in the Undulla Nose area, which led to an underreamed, openhole completion as the primary completion method for WSG wells. As appraisal programs moved away from the more prolific Undulla Nose area, areas having variable and lower permeability were encountered. These areas required reevaluating the traditional WSG completion method and considering implementation of hydraulic fracturing to improve production. On the basis of past wellbore failures, it was suspected that fracture complexity may be developing as a result of interaction of the created hydraulic fracture with the natural fractures and with the overall stress environment. When a program to incorporate hydraulic fracturing was considered, it was decided that an integrated diagnostics program would be essential in understanding the fracture geometry and overall stress environment to improve treatment designs and to help understand past-treatment results.

Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

In Brazil economically important coal deposits occur in the southern part of the Paraná Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paraná Basin. In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapuá, Barro Branco and Treviso seams). Seam thicknesses range from 1.70 to 2.39 m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapuá seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapuá seam has the highest inertinite content (33.8 vol%). Liptinite mean values range from 7.8 vol% (Barro Branco seam) to 22.5 vol% (Irapuá seam). Results from proximate analyses indicate for the three seams high ash yields (50.2 – 64.2 wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (> 50 wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the predominance of quartz and kaolinite (also pyrite). Gypsum, gibbsite, jarosite and calcite were also identified in some samples. Feldspar was noted but is rare. The major element distribution in the three seams (coal basis) is dominated by SiO2 (31.3 wt.%, mean value), Al2O3 (14.5 wt.%, mean value) and Fe2O3 (6.9 wt.%, mean value). Considering the concentrations of trace elements that are of potential environmental hazards the Barro Branco, Bonito and Irapuá seams (coal base) are significantly enriched in Co (15.7 ppm), Cr (54.5 ppm), Li (59.3 ppm), Mn (150.4 ppm), Pb (58.0 ppm) and V (99.6 ppm), when compared to average trace elements contents reported for U. S. coals. Hierarchical cluster analysis identified, based on similarity levels, three groups of major elements and seven groups of trace elements. Applying discriminant analyses using trace and major element distribution, it could be demonstrated that the three seams from Santa Catarina show distinct populations in the discriminant analyses plots, and also differ from the coals of Rio Grande do Sul analyzed in a previous study.

Estimating coal production peak and trends of coal imports in China

More than 20 countries in the world have already reached a maximum capacity in their coal production (peak coal production) such as Japan, the United Kingdom and Germany. China, home to the third largest coal reserves in the world, is the world's largest coal producer and consumer, making it part of the Big Six. At present, however, China's coal production has not yet reached its peak. In this article, logistic curves and gaussian curves are used to predict China's coal peak and the results show that it will be between the late 2020s and the early 2030s. Based on the predictions of coal production and consumption, China's net coal import could be estimated for coming years. This article also analyzes the impact of China's net coal import on the international coal market, especially the Asian market, and on China's economic development and energy security.

Relationship between Net Subsidence and Coal Cycle Parameters—A Statistical Appraisal from Subsurface Logs of Damuda Group, Talchir Gondwana Basin, India

Total thickness of strata and coal cycle parameters of the three formations, i.e. Karharbari, Barakar, and Barren Measures of the Damuda Group of the Talchir Gondwana basin were subjected to bivariate and multivariate statistical analyses. Polynomial regression lines were fitted to data sets consisting of total thickness of strata, number of coal cycles, and average thickness of coal cycles of the three formations of the Damuda Group. A significant direct relationship is observed between total thickness (net subsidence) of strata and number of coal cycles, while a significant inverse relationship exists between the number of coal cycles and their average thickness. Principal component and multiple regression analyses suggest that lithological parameters of the coal bearing strata reflect the dynamic of the basin subsidence. The sedimentary distributive mechanism in the form of lateral migration of streams or drainage diversion caused in response to differential subsidence of the depositional surface seem to be appropriate mechanisms for the development of coal cycles and peat swamps in the Talchir basin. Often during Karharbari sedimentation, peat accumulated in abandoned channels was scoured away by high energy migrating channels. On the other hand, Barakar peat swamps developed in a distal part of the flood plain, as a result of which many of the coal seams could be of appreciable thickness. The advent of arid climatic condition retarded the growth of vegetation to a larger extent that prevented profuse development of coal seams during the Barren Measures Formation.

Modeling of gas generation from the Cameo coal zone in the Piceance Basin, Colorado

The gas generative potential of the Cretaceous Cameo coal in the Piceance Basin, northwestern Colorado, was evaluated quantitatively by sealed gold tube pyrolysis. The H/C and O/C elemental ratios show that pyrolyzed Cameo coal samples follow the Van Krevelen humic coal evolution pathway, reasonably simulating natural coal maturation. Kinetic parameters (activation energy and frequency factor) for gas generation and vitrinite reflectance (Ro) changes were calculated from pyrolysis data. Experimental Ro results from this study are not adequately predicted by published Ro kinetics and indicate the necessity of deriving basin-specific kinetic parameters when building predictive basin models. Using derived kinetics for Ro evolution and gas generation, basin modeling was completed for 57 wells across the Piceance Basin, which enabled the mapping of coal-rank and coalbed gas potential. Quantities of methane generated at approximately 1.2% Ro are about 300 standard cubic feet per ton (scf/ton) and more than 2500 scf/ton (in-situ dry-ash-free coal) at Ro values reaching 1.9%. Gases generated in both low- and high-maturity coals are less wet, whereas the wetter gas is expected where Ro is approximately 1.4–1.5%. As controlled by regional coal rank and net coal thickness, the largest in-place coalbed gas resources are located in the central part of the basin, where predicted volumes exceed 150 bcf/mi^2, excluding gases in tight sands.

Geologic controls on transgressive-regressive cycles in the upper Pictured Cliffs Sandstone and coal geometry in the lower Fruitland Formation, northern San Juan Basin, New Mexico and Colorado

Three upper Pictured Cliffs Sandstone tongues in the northern part of the San Juan Basin record high-frequency transgressive episodes during the Late Cretaceous and are inferred to have been caused by eustatic sea level rise coincident with differential subsidence. Outcrop and subsurface studies show that each tongue is an amalgamated barrier strand-plain unit up to 100 ft (30 m) thick. Successive upper Pictured Cliffs tongues display an imbricate relation and are offset basinward, reflecting net shoreline progradation northeastward. Upper Pictured Cliffs barrier strand-plain sandstones underlie and bound thickest Fruitland coal seams on the seaward side. Controls on Fruitland coal-seam thickness and continuity are a function of local facies distribution in a coastal-plain setting, shoreline positions related to transgressive-regressive cycles, and basin subsidence. During periods of relative sea level rise, the Pictured Cliffs shoreline was temporarily stabilized, allowing thick, coastal-plain peats to accumulate. Although some coal seams in the lower Fruitland tongue override abandoned Pictured Cliffs shoreline deposits, many pinch out against them. Differences in the degree of continuity of these coal seams relative to coeval shoreline sandstones are attributed to either differential subsidence in the northern part of the basin, multiple episodes of sea level rise, local variations in accommodation and progradation, stabilization of the shoreline by aggrading peat deposits, or a combination of these factors. Fruitland coalbed methane resources and productivity are partly controlled by coal-seam thickness; other important factors include thermal maturity, fracturing, and overpressuring. The dominant production trend occurs in the northern part of the basin and is oriented northwestward, coinciding with the greatest Fruitland net coal thickness. Similar relationships between trends of thick coal seams of coeval origin with stacked shoreface sandstones exist in other Western Interior basins in the United States and serve as models for coalbed methane exploration in other basins of the world.

Design and full scale test of the fuel handling system : Liu, J. G. et al. Nuclear Engineering and Design, 2002, 218, (1–3), 169–178

More than 20 countries in the world have already reached a maximum capacity in their coal production (peak coal production) such as Japan, the United Kingdom and Germany. China, home to the third largest coal reserves in the world, is the world's largest coal producer and consumer, making it part of the Big Six. At present, however, China's coal production has not yet reached its peak. In this article, logistic curves and gaussian curves are used to predict China's coal peak and the results show that it will be between the late 2020s and the early 2030s. Based on the predictions of coal production and consumption, China's net coal import could be estimated for coming years. This article also analyzes the impact of China's net coal import on the international coal market, especially the Asian market, and on China's economic development and energy security.

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

Uncertainty in Coal Property Valuation in West Virginia: A Case Study

Interpolated grids of coal bed thickness are being considered for use in a proposed method for taxation of coal in the state of West Virginia (United States). To assess the origin and magnitude of possible inaccuracies in calculated coal tonnage, we used conditional simulation to generate equiprobable realizations of net coal thickness for two coals on a 7\( - \frac{1}{2}\) min topographic quadrangle, and a third coal in a second quadrangle. Coals differed in average thickness and proportion of original coal that had been removed by erosion; all three coals crop out in the study area. Coal tonnage was calculated for each realization and for each interpolated grid for actual and artificial property parcels, and differences were summarized as graphs of percent difference between tonnage calculated from the grid and average tonnage from simulations. Coal in individual parcels was considered minable for valuation purposes if average thickness in each parcel exceeded 30 inches. Results of this study show that over 75% of the parcels are classified correctly as minable or unminable based on interpolation grids of coal bed thickness. Although between 80 and 90% of the tonnages differ by less than 20% between interpolated values and simulated values, a nonlinear conditional bias might exist in estimation of coal tonnage from interpolated thickness, such that tonnage is underestimated where coal is thin, and overestimated where coal is thick. The largest percent differences occur for parcels that are small in area, although because of the small quantities of coal in question, bias is small on an absolute scale for these parcels. For a given parcel size, maximum apparent overestimation of coal tonnage occurs in parcels with an average coal bed thickness near the minable cutoff of 30 in. Conditional bias in tonnage for parcels having a coal thickness exceeding the cutoff by 10 in. or more is constant for two of the three coals studied, and increases slightly with average thickness for the third coal.

Methane emission and its utilization from Ostrava-Karviná Collieries in the Upper Silesian coal basin, Czech Republic

Abstract The Ostrava-Karviná part (OKR) of the Upper Silesian coal basin is the most important hard coal basin in the Czech Republic. This basin extends over an area of 1600 km 2 . The Carboniferous basin fill contains 255 seams with a net coal thickness of 150m. The methane content in the coal is estimated between 4.4 to 20m 3 /t. In the OKR, about 120 million cubic meters per year of methane are produced by gas drainage plants from a number of collieries. The methane is used in local industries. Several measures have been taken to increase the methane extraction in active mines and in areas of closed collieries. Additionally, pilot projects for coalbed methane production have been started in virgin coal bearing areas with no previous coal production. The authors’ company is progressing with such a pilot project, with the first coalbed methane wells completed recently. Results to date are encouraging. All these activities are designed to increase the safety in mines, to reduce methane emission to the atmosphere, and to develop new sources of energy.

Geologic and Hydrologic Controls on Coalbed Methane Producibility, Williams Fork Formation, Piceance Basin, Colorado: ABSTRACT

Structural and depositional setting, coal rank, gas content, permeability, hydrodynamics, and reservoir heterogeneity control the producibility of coalbed methane in the Piceance Basin. The coal-rich Upper Cretaceous, Williams Fork Formation is genetically defined and regionally correlated to the genetic sequences in the Sand Wash Basin, to the north. Net coal is thickest in north-south oriented belts which accumulated on a coastal plain, behind west-east prograding shoreline sequences. Face cleats of Late Cretaceous age strike E-NE and W-NW in the southern and northern parts of the basin, respectively, normal to the Grand Hogback thrust front. Parallelism between face-cleat strike and present-day maximum horizontal stresses may enhance or inhibit coal permeability in the north and south, respectively. Geopressure and hydropressure are both present in the basin with regional hydrocarbon overpressure dominant in the central part of the basin and hydropressure limited to the basin margins. The most productive gas wells in the basin are associated with structural terraces, anticlines, and/or correspond to Cameo-Wheeler-Fairfield coal-sandstone development, reflecting basement detached thrust-faulting, fracture-enhanced permeability, and reservoir heterogeneity. Depositional heterogeneties and thrusts faults isolate coal reservoirs along the Grand Hogback from the subsurface by restricting meteoric recharge and basinward flow of ground water. An evolving coalbedmore » methane producibility model predicts that in the Piceance Basin extraordinary coalbed methane production is precluded by low permeability and by the absence of dynamic ground-water flow.« less

Coalbed methane potential of some Variscan foredeep basins

Abstract Five Variscan foredeep coal basins in Germany and Great Britain are compared for coalbed methane (CBM) potential with the productive Black Warrior coal basin in Alabama. Although generally geologically similar, compared with the Black Warrior the European foredeep basins usually have much thicker coal measures, with more numerous coalbeds and thicker net coal thicknesses. Also compared are coal ranks, the present methane contents of the coals, potential depths of production and post-coalification histories. Despite basin to basin similarities, the CBM productive potential depends on characteristics unique to each coal basin. Only the unmined portions of the eastern Ruhr and western South Wales basins appear to be prospective for CBM; both the characterized by high exploration risks for potentially high economic returns. The Oxford and Kent basins appear to be non-prospective for CBM. The CBM potential of the Bristol-Somerset basin is speculative, given the lack of methane content data and severe tectonic compression. Subaerial exposure and erosion during Stephanian-Permian-early Triassic times may have destroyed the CBM potential of the Oxford, Kent and Bristol-Somerset basins. The Belgian and French foredeep basins are not evaluated here.