Biogas from livestock manure and organic residual is a carbon-neutral fuel. When replacing fossil fuels such as coal, oil or natural gas, it contributes to reducing greenhouse gas emission.
But that is not all. Biogas production represents better use of agricultural livestock manure, further reducing greenhouse gas emission and leaching of nutrients to the aquatic environment.
When plants grow, they absorb carbon dioxide from the atmosphere and use the carbon of carbon dioxide as a building stone. Later, the plants will perhaps be converted to animal feed and be eaten by a pig. The carbon is now inside a pig, and some of it will be transported into the liquid manure and then to the biogas facility, there to be converted into methane and carbon dioxide. Once biogas is used as fuel, the carbon dioxide will be emitted to the atmosphere again.
In this way, the emitted carbon dioxide will be offset by the carbon dioxide absorbed by the plants from the atmosphere when they grew.