Methanation Principles
Biomethanation is a natural process of organic matter degradation by micro-organisms in an absence of oxygen and away from the light.
This process is characterised by four different stages:
- Hydrolysis: degradation of the organic matter
- Acidogenesis: production of volatile fatty acids, acetates, H2 and CO2
- Acetogenesis: transformation of part of the fatty acids into acetates
- Methanogenesis: production of biogas from fatty acids and acetates
Each of these stages is carried out under very specific conditions, in terms of temperature and pH alike.
At the conclusion of these various stages, biogas is produced. It is a question of a methane-rich gas (between 60% and 80%), which, like natural gas, can be burnt for energy production purposes. Usually, this gas is used in a cogeneration module that enables electricity and heat to be produced together in order to maximise the installation’s overall energy yield.
The plant residues resulting from the methanation, the digestor’s sludge, is a high-quality manure, the properties of which vary according to the plants that have been digested, and it can be used as amendment.