Upgrading

If biogas is to be used as vehicle fuel or added to the natural gas grid it must be of natural gas quality. This is done in a upgrading plant where the biogas is purified. In this process corrosive components, particles, water och carbon dioxide is removed. By removing carbon dioxide the heating value is increased, i.e. the methane content. There are several upgrading techniques but the most common are pressurised water, chemisorption and PSA (Pressure Swing Adsorption)

The quality of the upgraded biogas often vary. To ensure the same heating value for the upgraded biogas as for the natural gas gas oil can be added after the upgrading. This is often a cost-effective and reliable solution.