Renewable natural gas, also known as sustainable natural gas, is a biogas which has been upgraded to a quality similar to fossil natural gas. A biogas is a gas methane obtained from biomass. By upgrading the quality to that of natural gas, it becomes possible to distribute the gas to customers via the existing gas grid, within existing appliances. Renewable natural gas is a subset of synthetic natural gas or substitute natural gas (SNG.
Renewable natural gas can be produced economically, and distributed via the existing gas grid, making it an attractive means of supplying existing premises with renewable heat and renewable gas energy, while requiring no extra capital outlay of the customer.
The existing gas network allows distribution of gas energy over vast distances at a minimal cost in energy. Existing networks would allow biogas to be sourced from remote markets that are rich in low-cost biomass (Russia or Scandinavia for example).
The UK National Grid believes that at least 15% of all gas consumed could be made from sewage slurry, old sandwiches and other food thrown away by supermarkets, as well as organic waste created by businesses such as breweries.