Biomethane

Biomethane is a renewable gas obtained by purifying the biogas generated during the anaerobic digestion of organic matter until it reaches a quality equivalent to natural gas. This purification process, known as upgrading, mainly removes carbon dioxide, water and other impurities to concentrate the methane.

Unlike raw biogas, biomethane has a methane content high enough to be injected into the gas grid or used as a fuel, making it a key element of the circular economy and of decarbonising gas consumption.

How biomethane is produced

The process starts with the anaerobic digestion of organic waste such as livestock slurry and manure, sewage sludge, the organic fraction of municipal waste or agri-food by-products. This digestion yields biogas, a mixture of methane and carbon dioxide. Upgrading separates these components through technologies such as adsorption, water or pressure scrubbing, or membranes, leaving a gas with a methane content suitable for its end use.

A related source is landfill gas, captured from the decomposition of waste in controlled landfills, which can also be treated to obtain biomethane.

Main uses

• Grid injection: once the required quality is reached, biomethane can be injected into existing transmission and distribution networks and replace fossil natural gas in any grid-connected use.
• Transport fuel: compressed or liquefied, it can power gas-ready vehicles, offering a lower-footprint option for fleets and heavy transport.
• Industrial and thermal use: as a renewable gas for heat processes or cogeneration.

Role in decarbonisation and policy framework

Biomethane supports decarbonisation because it makes use of waste that would otherwise emit greenhouse gases and displaces fossil natural gas. At EU level, the REPowerEU plan set a target of producing 35 billion cubic metres of biomethane per year by 2030 to reduce dependence on gas imports.

In Spain, the Biogas Roadmap approved by the Council of Ministers develops the projections of the National Integrated Energy and Climate Plan (PNIEC) and aims to significantly increase biogas and biomethane production by 2030. The Spanish gas system, with its extensive transmission and distribution network, is technically ready to integrate renewable gases.

Biomethane and renewable energy

Biomethane is part of renewable energy sources and allows organic waste to be valorised instead of landfilled. Its real impact depends on the feedstock used, process efficiency and methane-leak control, so its footprint should be assessed case by case.

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