Natural Gas and Coal Bed Methane (CBM)

Natural gas is growing in importance as a source of environmentally responsible energy in Australia, USA, Europe, and Asia. In Australia this has followed sustained market reforms, taxation changes and legislative incentives, together with pressure from government and lobby groups. Energy produced from methane gas generates lower carbon emissions than coal. Many European nations place caps on the greenhouse gases companies can produce. Companies can offset their emissions by buying carbon credits from developing-world projects that reduce greenhouse-gas emissions. The use of natural gas as an energy source produces far less greenhouse gases than coal or oil.

Coal Beds are a source of natural gas, mostly methane (CH4) which is the main component of commercial gas and which is formed during the conversion of organic plant matter to coal. The gas molecules are attached (adsorbed) to the coal by hydrostatic (water) pressure. This gas is present within the pores, cleats and fractures of the coal, which creates a large surface area capable of holding larger volumes of gas than other conventional reservoirs such as sandstone. The volume of gas in the coal bed is dependent upon the thickness and depth of the seam and the extent of the fracture network.
Gas is extracted by pumping water from the coal bed and the resulting lowering of pressure releases the gas. It is then piped to a gas plant and the extracted water is directed to evaporation ponds. Production of CBM is achieved by drilling into the seams and reducing the pressure within the seam. The pressure is normally the pressure of a column of water extending from the coal seam to the surface. It is reduced by pumping water from the seam thus allowing the adsorbed methane to be released.
Coal bed methane can partly replace coal as a fossil energy source, and it sometimes occurs where other conventional resources of oil and gas are not present. Coal bed methane accumulations are widespread, commonly basin-wide, and are characterized by large in-place resources. The use of natural gas in the production of electricity produces on average less than 50% of the greenhouse gas emissions of that produced by coal, making natural gas an environmentally responsible alternative.