"Large amounts of methane-rich gas are generated and stored in coalbeds. Recently, commercial production of coalbed methane has been undertaken in the United States, and this development will be expanded to other countries. The U.S. Geological Survey is engaged in detailed studies of the controls, distribution, and recoverable resources of coalbed methane, particularly as they affect the release of gas and water to the environment."Of course, no energy source is without its problems:
Dudley Rice, U.S. Geological Survey
Major resources of coalbed methane are associated with immense amounts of coal, but are accompanied by significant environmental challenges.The recoverable reserves are estimated to be about a 5 year supply of gas at current consumption levels.
Coalbed methane can be used as an energy source that is environmentally more acceptable than mining and combustion of coal. It can partly replace coal as a fossil energy source, and it sometimes occurs where other conventional resources of oil and gas are not present. Coalbed methane accumulations are widespread, commonly basinwide, and are characterized by large in-place resources. Although most wells will encounter gas in these widespread accumulations, production rates will be highly variable, even within a small area, because of the heterogeneous nature of coalbeds. The in-place coalbed methane resources of the United States are estimated to be more than 700 trillion cubic feet (Tcf), but less than 100 Tcf may be economically recoverable. Worldwide estimates of in-place resources are as much as 7,500 Tcf, but this number is uncertain because of the scarcity of basic data on coal resources and gas content. Basin-wide studies are needed to determine controls of the occurrence, availability, and recoverability of coalbed methane in the United States and other countries that need clean energy resources. Underground coal-mining areas, such as the Appalachian basin, should be emphasized because of the need to reduce atmospheric methane emissions. Most previous exploration and research efforts have been in the San Juan basin and the Black Warrior basin. However, since each coal-bearing basin has unique attributes, coalbed methane issues need to be studied separately in each basin.
Update: Our Canadian neighbors have some, too, but challenges abound:
Can producers eventually overcome the CBM challenges in B.C.? "I have no idea," said Michael Gatens chairman of the Canadian Society for Unconventional Gas. That terse comment accentuates industry doubts surrounding CBM in B.C., which has one of the most outspoken environmental lobbies in North America.
"Unconventional gas is a big, powerful resource," said Gatens,a geologist by profession. "You know the gas is there, generally, but you don't know if you can get it out." Noting CBM development in B.C. is still in its early stages, he suggested much work is necessary before the sector is up and running well.
"There's not nearly as much resource in British Columbia as there is in Alberta," said Gatens, whose Calgary-based firm MGV Energy Inc. has achieved commercial success in B.C.'s neighbouring province.
B.C.'s CBM is much more technologically challenging because it's distributed in a much different fashion. In Alberta, one type of coal - in the Horseshoe Canyon formation - is available in one large regional play on accessible terrain. Alberta CBM plays have access to an established oil and gas infrastructure and surface landowners are more knowledgeable of the industry. In B.C., by contrast, the coal is in mountainous areas and is localized in areas like Merritt, Princeton, Hat Creek and Vancouver Island. There's little oil and gas development outside of northeastern B.C., and surface landowners are inexperienced in petroleum development.