Wärtsilä's Puregas CA process recovers more than 99.9% of the biomethane present in the raw biogas. The process separates the CO2 from the biogas by a process of chemical absorption. The selective organic solvents (Amine) used in this process are so efficient that the end product can contain more than 99% methane and is suitable for vehicle fuel or to be injected into the natural gas grid.