Methane digesters are systems that use anaerobes to produce methane through fermentation. Methane is a main constituent of natural gas and can be readily substituted for that nonrenewable resource.

The anaerobes used in methane digesters are methanogenes, bacteria belonging to the genera Methanobacterium; Methanosarcina; and Methanoccus. They can be found in the gastrointestinal tracts of animals such as cows and other ruminants, as well as in soil, water, and sewage. In septic tanks, bacteria liquefy some of the organic matter; which releases energy for the bacteria and by products such as methane and carbon dioxide.

Methane digesters are also known as biogass digesters and organic digesters. The central portion is an airtight drum, called a digester unit, which contains the methanogenes. Raw material is place into the drum, and the unit is kept at a constant temperature of about 95°F (35°C). Some of the methane produced...