Methane Digestion (Biogas)

Methane (anaerobic) digestion is a series of processes for biofuel production in which microorganisms break down biomass (often sewage or animal waste; also plant waste) in the absence of oxygen to produce a gas: “biogas” (http://en.wikipedia.org/wiki/Anaerobic_digestion). Biogas is a renewable methane and carbon dioxide-rich biofuel suitable for both heat and electricity production. The solid and liquid “digestates” that remain after biogas production can be used as compost on crops. Integrated into waste management and landfills, anaerobic digestion prevents potentially huge amounts of methane and carbon dioxide from entering the atmosphere. As with other biofuels, use of biogas helps replace fossil fuels to reduce GHG emissions and provide energy independence. The UN Development Programme identified biogas as one of the most useful decentralized sources of energy (Amuyla et al. 1997).

The wastewater from the biogas production process has high levels of biochemical oxygen demand and must usually be further treated before release to prevent eutrophication of natural waterbodies. In the North Coast, Humboldt is one county practicing dairy waste methane digestion. See “Biofuels.”

Citations:

Amulya K., N. Reddy, Robert H. Williams, and Thomas B. Johansson (Editors). 1997. Energy After Rio: Prospects and Challenges. UNDP/BDP Energy and Environment Group. 36 pages