Biogas is a renewable fuel that is produced when organic matter, such as manure and sewage sludge is broken down by microorganisms in the absence of oxygen. This process is called anaerobic digestion. For this to take place, the waste material needs to be enclosed in an environment called a dome where there is no oxygen.
Digestion carried out by these microorganisms creates methane, which can be used as it is locally or upgraded to biogas equivalent to natural gas quality, enabling the transport of the biogas over longer distances. Material containing organic nutrients is also produced in the process, and this can be utilized for purposes such as agriculture.
Stages in Biogas Production
Biowaste is crushed into smaller pieces and slurrified to prepare it for the anaerobic digestion process. Slurrifying means adding liquid to the biowaste to make it easier to process.
Microbes need warm conditions, so the biowaste is heated to around 37 °C.
The actual biogas production takes place through anaerobic digestion in large tanks for about three weeks.
In the final stage, the gas is purified (upgraded) by removing impurities and carbon dioxide.