Natural gas normally consists of 80% or more methane with the balance comprising such hydrocarbons as butane, ethane and propane. In some cases it may be sour, containing small quantities of highly poisonous hydrogen sulfide. CBM (Coal Bed Methane) is a sweet gas consisting of 95% methane, and is considered an unconventional natural gas resource because it does not rely on a 'conventional' trapping mechanism or stratigraphic trap. Instead CBM is "adsorbed" or attached to the molecular structure of coal - a surprisingly efficient storage mechanism as CBM coals can contain as much as seven times the amount of gas typically stored in a conventional natural gas reservoir such as sandstone or shale. The principal sources of CBM are either biogenic, producing a dry gas which is generated from bacteria in organic matter, typically at depths less than 1,000 feet, or thermogenic, which is a deeper wet gas, formed when organic matter is broken down by temperature and pressure.

What is GOB Gas? When coal beds are formed through the compression and heating of organic materials over geologic time spans the generation of methane entrapped in the coal is an integral part of the process. As the coal beds are mined, this entrapped, or adsorbed, methane is released. Apart from serious environmental protection reasons methane gas vented into the atmosphere is destroying the ozone layer. Further, the presence of methane gas in coal mining poses a serious danger for security reasons. Once air is combined with methane gas and forms only a 5-15% mix it becomes highly explosive.

Coal mining companies employ different methods to reduce the possibilities for these explosions. The principal method is to force very large quantities of ventilation air into the underground workings to keep the methane content at the coal mining face below the lower explosive limit of 5% methane. A secondary method that has been developed over the last few years is to drill wells into the coal seam in advance of mining in order to extract much of the methane before it is released into the mine, thereby reducing the load on the ventilation system. At the same time, methane produced from these wells is usually of good quality and can be used for power generation. This not only reduces methane emissions to the atmosphere but converts the methane into a useful resource. When the mining operations reach the area of these gas extraction wells, methane continues to be produced , but is then typically mixed with air from the mine ventilation system. At that time, gas extracted from the wells, referred to as GOB-Gas, may contain 35% to 75% methane. With adequate treatment it is still suitable for power generation.