The whole idea comes from a natural biological process : the decomposition of organic matter. As the matter degrades, it produces gas that is released into the atmosphere and contributes significantly to the greenhouse effect. The strength of methanization is that it creates a framework around this decomposition that allows the gas to be trapped and transformed into green energy.
This framework sets up conditions that promote degradation: absence of oxygen (anaerobic) and heat effect (38 °C). It is in this structure, called a digester, that bacteria carry out a chemical transformation that produces methane (biogas) on one side, and a residue (digestate) on the other.
Biogas is composed of half carbon dioxide (CO2) and half methane (CH4), which is city gas or "natural gas". It also contains traces of other gases (H2S, NH3) and water (H2O).
This biogas can be burned in an engine to produce electricity and heat, this is called cogeneration . Or it can be purified, in order to keep only the bio-methane (CH4), and injected into the French natural gas networks: this is called injection .
Digestate is made up of solid or liquid residues from methanization. It is a natural organic fertilizer: digestion does not consume the nitrogen, phosphorus and potash contained in organic matter. These elements (which are the main nutrients of the plant) are therefore present in the digestate, which will be spread in the fields to fertilize the crops. Digestate thus allows farmers to approach fertilizer autonomy.
HOW A METHANIZER WORKS
