Landfill gas is approximately 40% methane, with the remainder being mostly carbon dioxide. As with other gas produced from anaerobic digestion, it also contains varying amounts of nitrogen and oxygen gas, water vapour, hydrogen sulphide, and other contaminants.
Most of these other contaminants are known as “non-methane organic compounds” or NMOCs. Some inorganic contaminants, such as mercury and radioactive tritium, can also be present in the gas of some landfills. The gases produced within a landfill can be collected or flared-off.
The raw gas can be processed into biomethane by removing the water, carbon dioxide, nitrogen, hydrogen, oxygen and any other trace contaminants (this process is identical to biogas scrubbing).
As a readily available fuel, the processed gas can provide raw heat for scrubbing procedure, be used for generating electricity on-site through the use of micro turbines, steam turbines, or fuel cells. The gas can also be sold off-site into natural gas pipelines.
The majority of this gas is used as on-site fuel to power generators creating electricity.