This Practice Note provides an introduction to the production of biomethane (a form of biogas and also known as ‘green gas’ in light of its renewable nature). The Practice Note included details of biomethane’s common uses and an overview of the injection of biomethane into the Great Britain (GB) gas grid. It also includes an examination of the funding options available for biomethane projects, an outline of key GB regulation and applicable industry codes; an examination of the GB market and grid connection process for biomethane; and examples of gas to grid biomethane projects.