Biogas is a natural gas mainly consisting of methane and carbon dioxide, obtained from the anaerobic fermentation of organic matter from different sources: animal manure, vegetable biomass, agri-food industry waste. Fermentation occurs in digesters, in a wet environment without oxygen.
The biogas generation process occurs in three steps:
- Preparation of the material
- Post treatment of residue
The organic matter is collected in a primary pit, sterilised to remove any harmful germs and transferred to the digester for the fermentation process. The gas produced during the anaerobic digestion process consists in 50-70% methane and 30-50% carbon dioxide.
Lastly, biogas is conveyed into a thermal combustion engine: the co-generator.
Part of the output power is injected into the distribution grid, and partly used to supply the anaerobic digestion plant. The thermal energy produced by the engine can be used to heat the digester and control the biogas production process, to heat greenhouses, or injected into a district heating grid.
A biogas power plant is made up of:
- A supply section
- A biogas digestion section
- A co-generation section
The co-generation section is made up of:
- Biogas treatment system
- Central heat exchanger with dual circulation pump, piping, valves
- Power transformer and output section