Quote (RzChaos @ Mar 11 2016 06:03pm)
It's the gas created through the anaerobic digestion of organic material.
Bacteria that exist in anaerobic environments (oxygen deficient) digest organic material, and release "biogas", which is almost entirely made up of methane/CO2
Man made "biogas" is typically made using anaerobic digesters --> Tanks with oxygen removed, and maintained at a temperature/pressure optimal for the growth of anaerobic bacteria.
what is anaerobic digesters