Coal Seam Gas (CSG) is a form of natural gas, and is variously known as seam gas, coal seam methane (CSM) and coalbed methane (CBM), but is probably best described as seam gas as it may contain gases other than methane.  Carbon dioxide is a common (and undesirable) component, and indeed in some areas may be the sole gas present.  The desired seam gas is thus that which is high in methane.  Where the methane content is around 98%, the gas is termed pipeline quality.  Where methane content is significantly lower than this, beneficiation (stripping) processes may be required, and if the stripped gas is largely carbon dioxide, additional costs will be incurred in its disposal.

 

CSG was largely unknown as a stand-alone energy resource until the 1980's when tax concessions were introduced in the USA for "alternative" energy resources to conventional petroleum.  From that time it has rapidly emerged as a very significant resource, and one which is far more environmentally friendly than coal.  New South Wales  (and most administrations) consider seam gas to be a petroleum product for legislative purposes.

 

Methane - CH4 - is a colourless and odourless non-poisonous gas which is lighter than air.  It is non-combustible alone, but forms an explosive mixture with air/oxygen, when water and carbon dioxide are the only products. By comparison, combustion of coal results in the production of a range of additional undesirable by-products (SOX, NOX, heavy metal compounds etc)