Anaerobic Digestion

Anaerobic Digestion is a proven technology that extracts energy in the form of biogas from organic waste. It is the biological conversion of the organic fraction of waste to biogas and digestate in the absence of oxygen. The process takes place in an airtight reactor vessel, with feedstock fed into the vessel and biogas and nutrient rich solid and liquid digestate, which can be used as a biofertiliser, taken out.

Biogas is made up mostly of methane (about 55-70%), the main constituent of natural gas, and it can be used as a chemical feedstock or fuel. The other components of biogas are carbon dioxide (about 30-45%) and traces of hydrogen sulphide and ammonia.

One of the benefits of Anaerobic Digestion is that it allows both a mass and a volume reduction of the waste input. Between 40-60% of the organic matter in the process is converted to biogas, the rest is left as odour-free nutrient rich digestate.

Industrial scale plants have been successfully deployed for over 20 years in mainland Europe. There is currently over 6 million tonnes/year of capacity divided over 200 plants across 17 European countries.