The vessel in which anaerobic digestion takes place. May be constructed to also store the biogas produced by anaerobic digestion.; A biogas digester, also known as a methane digester, is a piece of equipment which can turn organic waste into usable fuel. A biogas digester, also known as a methane digester, is a piece of equipment which can turn organic waste into usable fuel. In addition to providing a source of renewable fuel, biogas digesters also provide low-cost fuel to people in poverty, and they help to dispose of waste materials which would otherwise be discarded.