Biomethane (RNG)
Biogas upgraded to more than 95% methane so that it meets natural gas quality standards and can be injected into the gas grid or used as vehicle fuel.
Biomethane, called renewable natural gas (RNG) in North America, is chemically interchangeable with fossil natural gas. Upgrading removes CO2, H2S, water and siloxanes from biogas. Main technologies:
- Membrane separation: now the most common in Europe; 0.2–0.3 kWhe per m3 of raw biogas
- Water scrubbing and pressure swing adsorption
- Amine scrubbing: very low methane slip (below 0.1%) but needs heat at 120–160°C
Methane slip ranges from below 0.1% to about 2% by technology. The separated CO2 stream is nearly pure and can be sold or stored, giving negative-emission potential. Production costs are typically EUR 55–100/MWh, well above fossil gas at EUR 30–50/MWh, so plants rely on support such as feed-in premiums, the US Renewable Fuel Standard and California's Low Carbon Fuel Standard.
Europe produced roughly 5 bcm of biomethane in 2024 (European Biogas Association), and the REPowerEU plan targets 35 bcm by 2030. Lifecycle carbon intensity can be negative when it displaces manure methane emissions, a credit that makes dairy RNG the most valuable fuel pathway under California rules.
Related terms
All terms →- Biogas
A gas mixture of roughly 50–70% methane and 30–50% CO2 produced by anaerobic digestion of organic matter such as manure, food waste, sewage sludge and energy crops.
- Anaerobic digestion
The microbial breakdown of organic matter in the absence of oxygen, producing biogas and a nutrient-rich digestate usable as fertiliser.
- Natural gas
A fossil fuel composed mainly of methane, used for power generation, industrial and residential heat, and as a chemical feedstock for hydrogen and ammonia.
- Guarantee of origin / REC
A tradable certificate proving that 1 MWh of electricity was generated from a specific source, used to substantiate renewable or low-carbon claims.
- Lifecycle emissions
Total greenhouse gas emissions of a product or power source across its full life, from raw material extraction and manufacturing through operation to decommissioning.