Biomethane

Biomethane is a renewable gas made by upgrading biogas until it is chemically almost the same as the natural gas in the grid. Biogas comes mainly from anaerobic digestion, in which microbes break down food waste, manure, sewage sludge or crops without oxygen. Raw biogas is a mixture of methane and carbon dioxide with traces of other gases, so it cannot go straight into the grid.

From biogas to grid gas

Upgrading removes the carbon dioxide, water, hydrogen sulphide and other impurities. Common methods include water scrubbing, membrane separation, pressure swing adsorption and chemical (amine) scrubbing. The cleaned gas is then:

• measured and checked against the gas quality rules that apply to the network;
• usually enriched with a little propane to match the energy content of grid gas;
• odorised, so that leaks can be smelt, and injected into the local gas network.

Once in the grid it mixes with fossil gas and is used in the same boilers, cookers and industrial plant. It can also be compressed for use as a vehicle fuel. The carbon dioxide removed during upgrading can be captured and sold, for example to the food and drinks industry.

Green Gas Support Scheme

In Great Britain, new biomethane plants injecting into the grid can apply for the Green Gas Support Scheme (GGSS), run by Ofgem. It pays a tariff per unit of biomethane injected, normally for 15 years, and is funded by the Green Gas Levy on licensed gas suppliers. The deadline for new applications is 31 March 2028. In December 2025 the government said it would extend the deadline for plants to start injecting from 31 March 2028 to 31 March 2030, with payments for late-commissioning plants ending by 31 March 2043. Check Ofgem’s guidance for the current rules; this is general information, not advice.

Read more: Biomass energy: how it works, where it is used and the debate.