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The growing insufficiency in oil and natural gas supplies and the rise in energy consumption all over the world have created new opportunities to develop other energy products and technologies. Coal again acquired an important role in the global energy survey. International organizations are now conscious and resolved to systematically move into clean/cleaner coal technologies (CCTs) and, above all, into zero (or near zero) emission technologies (ZETs). Carbon capture and storage (CCS) technologies, acting in a complementary way to CCTs, are becoming one of the solutions to facing climate changes, permitting us not to avoid entirely but to minimize the green house gas effect (GHGE) to an acceptable level. It is also imperative to emphasize the actual crucial role of coal as a natural gas source rock and as a reservoir. Yet it is also important to understand that when coal has a high gas generation potential it does not necessarily imply that coal also has a high gas storage capacity and a high gas circulation performance. This investigation aims to compare the gas storage capacity and the gas circulation behavior between Gondwana and North Atlantic coal types. Two sets of Gondwana and North Atlantic coal types, with different ranks, were selected in the present research. Results revealed that the two sets of samples corresponded to different facies and, consequently, have different chemical and physical properties and quite different gas storage and gas circulation behaviors. In general terms, "North Atlantic-type" coals have a higher CH₄ storage capacity than "Gondwana-type" coals due to differences in their petrographic characteristics, mainly in terms of vitrinite content and rank but also, although in a smaller scale, in terms of gas sorption temperatures. Diffusion coefficient values present a higher dependency on temperature changes than on gas storage capacities due to the high activation energy induced by high temperatures. © 2010 by Begell House, Inc.