Anaerobic digestion, or AD, is the biological process that breaks down biological materials like compost or manure into biogas. Livestock manure accounts for 3 percent of man-made methane emissions globally. Methane, when captured and stored, can be used to generate electricity and heat, or it can be processed into natural gas fuel. By capturing the biogas, we are also preventing the release of methane, one of the most potent greenhouse gases, to the atmosphere.