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 includes details of biomethane’s common uses and an overview of the benefits and drawbacks associated with biomethane’s incorporation into the gas grid. It also includes an examination of the structure of a gas to grid project as well as an outline of the key documents, an examination of the GB market and grid connection process for biomethane; and the legislation and regulation of gas to grid biomethane projects.