Renewable energies are increasingly important. An ever growing number of businesses and private households, as well as energy companies, are backing the sustainable creation of electricity and heat from renewable raw materials. Many countries in the world support the expansion and use of renewable energy – this also includes aid and subsidies in the creation and operation of a biogas plant.

When organic substances ferment, biogas is produced. In nature, for example, this occurs in bodies of water and in moors, but also in the stomachs of ruminants. The controlled fermentation process takes place in the fermenters of a biogas plant. In these large containers, the organic substrate is decomposed by methane bacteria. The gas mixture produced by this is around 60 % energy-rich methane biogas. The so-called digestate that remains after this metabolic process can also be completely reused as valuable natural fertilizer.

Biogas plant is a combination of digester and gas holder either a single chamber or separate chambers depending upon the design of the plant. There should be an inlet portion in the digester for the input of organic matter and an out let portion for discharging the treated organic materials from the digester. The fermentation process takes place in the digester portion of the plant. Single stage or multi stage digestion facilities have been incorporated with each biogas plant based on the design. The biogas produced will be collected in the gas collector portion of the plant.

Many categories of biogas plants have been developed in different models. Biogas plants can broadly be classified based on the application such as domestic, Institutional and commercial. Three categories of biogas plants are available these days. Those are batch type, semi continuous type and continuous type.