Renewable natural gas

Renewable natural gas is a biogas which has been upgraded to a quality similar to natural gas. A biogas is a gas 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, and burned within existing appliances. Renewable natural gas is also known as Sustainable Natural Gas, and 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).

Manufacturing
A biomass to SNG efficiency of 70% can be achieved. Manufacturing costs are minimized by maximising production scale, and by locating plant next to transport links (e.g. a port or river) for the chosen source of biomass. The existing gas storage infrastructure would allow the plant to continue to manufacture gas at the full utilisation rate even during periods of weak demand, helping minimise manufacturing capital costs per unit of gas produced.

Renewable natural gas can be manufactured through two main processes; anaerobic digestion of organic (normally moist) material, or thermal gasification of organic (normally dry) material. In both cases the gas from primary production has to be upgraded in a secondary step to produce gas that is suitable for injection into the gas grid.