Biomethane is a renewable energy source identical to “natural gas” and distributed via the gas transmission and distribution network to many businesses and households across Europe. It is made by cleaning up biogas, leaving just the methane, and then injecting it into the network.

Biogas is produced by the biological degradation of biomass, primarily agricultural substrates such as manure, other agricultural by-products, cover crops (crops grown to enrich the soil), energy crops (maize, sorghum, rye, sugar beet, etc.), and organic waste from rural districts, towns and villages, such as cut grass, waste food and by-products of the food industry. These materials are fermented by bacteria in air-tight tanks, called digesters, producing biogas in a multi-stage process.

Like natural gas, the essential component of biogas that makes it a source of energy is methane (CH4), a flammable gas. Depending on the substrate feeding the biogas plant, the methane content of the biogas can fluctuate between 50 and 65 per cent. The second component of biogas is carbon dioxide (CO2), which accounts for 35 to 50 per cent. The carbon dioxide (CO2) generated in the biogas process is considered climate neutral because the biogenic material draws it from the atmosphere for its growth. Other components of biogas are water (H2O), oxygen (O2), and traces of sulphur and hydrogen sulphide (H2S). If the biogas is upgraded to biomethane – with about 98 per cent methane – that biomethane has the properties of natural gas.

When considering options to decarbonise the transport sector in Europe, biomethane offers a unique set of benefits and constitutes a powerful weapon against climate change. Anaerobic digestion of manure and similar materials helps avoid methane emissions, which are up to 23 times more harmful than CO2. Without biogas technology, methane is released into the atmosphere from decomposing manure and waste, such as sewage sludge, municipal waste, agro-industrial runoff and agricultural residue. While burning biomethane does emit CO2, the amount produced is of biogenic origin, meaning it is produced by natural, biological processes, and so it has no carbon footprint. In addition, methane emissions that arise from decomposing waste that is not processed into biomethane are avoided. As a result, the total carbon footprint is very low compared to fossil fuels and can even go into the negative.

The use of biomethane or a blend with natural gas as a vehicle fuel significantly reduces pollutant emissions, such as hydrocarbons and carbon monoxide, compared to gasoline- and diesel-powered engines, and is also well below the levels of biodiesel and bioethanol. This offers an ideal way to reduce harmful emission levels in cities, which currently cause 400,000 premature deaths a year in Europe.

Biomethane use in transport also has the indirect environmental advantage of contributing towards a circular economy. In addition to energy, the anaerobic digestion process that produces biomethane also supplies digestate, a valuable organic substance that can be used as an organic fertiliser in agriculture, replacing millions of tons of CO2-intensive mineral fertiliser. Digesting waste and repurposing it for fuel is a much cleaner alternative to landfills and incineration.