Anaerobic decay, methane gas and biogas generators

Anaerobicdecay occurs when bacteria and fungi break down dead matter without oxygen. This can happen naturally in some soils, particularly water logged soils, and in lakes and marshes. When people overwater their houseplants and flood the roots, anaerobic decay can occur, which can kill them.

The products of anaerobic decay are methane and carbon dioxide. We use methane as a fuel. Both gases are greenhouse gases, which contribute towards global warming.

Biogas

We can use the process of anaerobic decay or decomposition to provide us with fuel. Together the methane and carbon dioxide produced are called biogas. This is a source of renewable energy. Biogas generators are large vessels in which animal waste or specially grown crops such as maize are allowed to anaerobically digest. If domestic waste is used as a source of methane, this also reduces the volume of domestic waste added to landfill sites.

A diagram showing how a biogas generator works.  Biogas is generated from manure and then used as fuel.The process of biogas generation
A biogas generator
An industrial biogas generator