Coalbed Methane is natural gas adsorbed into the matrix of coal within coal seams. This natural gas is almost entirely methane and is typically free of heavy hydrocarbons, condensates, or impurities such as hydrogen sulfide (H2S). Methane released during mining processes can pose a hazard to workers in and around the coal seam, and methane vented to the atmosphere contributes to greenhouse gas emissions. The extraction of coalbed methane during coal mining processes has the dual benefit of reducing these risks and generating a source of sellable natural gas.
Biogenic Gas (Biogas)
Biogenic gas, or biogas, is produced by methanogens, microorganisms known for their ability to break carbon dioxide down into methane using a process called methanogenesis in anaerobic environments. Methanogens can produce capturable methane from many waste sources, including livestock manure, food waste, and landfills. Small-scale biogas technologies such as anaerobic digesters are used to collect the methane, which can then be combusted to generate electricity or heat.
At very high pressure and low temperature, molecules methane gas can become trapped within a solid lattice of water molecules and crystalize. These crystalline solids are called methane hydrates and can be found in extreme conditions such as arctic regions, beneath permafrost, beneath the seabed of deep-sea areas, and in shallow sediments along deep-sea continental margins. While methane hydrates are currently thought to be extremely abundant, research is ongoing to develop technologies that will make production economically feasible.
Synthetic Natural Gas (SNG)
Synthetic natural gas, or SNG, is a gas obtained by heating coal or refining heavy hydrocarbons. The creation of SNG typically requires the intermediary syngas (link!), an output of petrochemical processing.