https://phys.org/news/2018-05-biogas-subsidies.html

Biogas is produced from the breakdown of organic matter, such as agricultural residues. Besides locally dealing with organic waste, the biogas combustion produces electrical energy besides heat. Today, this process represents about 10% of our green energy.

The combustion of biogas is widespread, as governments grant subsidies for this sort of energy. In Europe, subsidies for biogas combustion vary between 20 and 276 euros per megawatt-hour. The actual price of electricity is only about 40 euros.