Bioenergy and Biogas Explained: Biomass, Biomethane and Biofuels

Bioenergy is the oldest energy source humans use and still the largest renewable by primary energy. The term covers firewood on a cooking fire, pellet boilers, wood-fired power stations, farm biogas digesters and the ethanol in petrol. No other renewable is argued over as much. Done well, it turns waste into energy and cuts methane emissions. Done badly, it drives deforestation, competes with food and, for decades, emits more CO₂ than the fossil fuels it replaces. This guide separates the two, with numbers.

The scale of bioenergy

Bioenergy supplies roughly 10% of world primary energy (IEA). About half is traditional biomass: wood, charcoal, crop residues and dung burned in open fires or simple stoves, mostly in sub-Saharan Africa and South Asia. The WHO links household air pollution from such cooking to over 3 million premature deaths a year. The other half is modern bioenergy: heat for buildings and industry, electricity, and transport fuels.

In electricity, bioenergy generated about 710 TWh in 2025, around 2.2% of world electricity (Ember / Our World in Data). Liquid biofuels supply around 4% of global transport fuel demand, led by the US (maize ethanol), Brazil (sugarcane ethanol) and Indonesia (palm biodiesel).

Main pathways

Energy content of common fuels

Convert between them with the energy unit converter.

Biogas: from manure to methane

In anaerobic digestion, microbes break down organic matter in an oxygen-free tank at 35–55 °C. The products are biogas (50–65% methane) and digestate, a nutrient-rich fertiliser. The big win is that it captures methane that would otherwise escape from manure stores or landfills.

Worked example: a 300-cow dairy farm

• Slurry: 300 cows × 18 t/yr = 5,400 t at ~25 m³/t = 135,000 m³ biogas.
• Add 1,500 t of food waste from a nearby town at ~120 m³/t = 180,000 m³.
• Total: 315,000 m³ at 58% methane → 315,000 × 0.58 × 9.97 ≈ 1.82 GWh primary energy.
• CHP engine at 40% electric: ~730 MWh electricity (≈ 85 kW continuous) and ~800 MWh of usable heat (some used to warm the digester).
• Methane emissions avoided from open slurry storage plus fossil displacement: on the order of 1,000–2,000 t CO₂e/year, depending on the baseline.

Model your own feedstocks with the biogas calculator.

Biomethane

Upgrading strips the CO₂ out of biogas (with membranes, water scrubbing or amine absorption) and leaves a gas that can stand in for natural gas. Europe is the largest market, with over 1,500 biomethane plants producing roughly 4–5 billion m³ a year (European Biogas Association). The EU’s REPowerEU target is 35 bcm by 2030. The IEA puts sustainable global potential at over 700 Mtoe a year, of which only a small fraction is used. Even if all of it were tapped, it would cover only part of today’s natural gas demand.

Biomass heating

Modern pellet and wood-chip boilers run automatically and efficiently, and they are common in Austria, Germany, Italy, Scandinavia and the Baltics. Wood is the EU’s main source of renewable heat.

Pellets in Europe typically cost €0.06–0.10 per kWh of heat (2024–2025), about the same as gas and less than electric resistance heating. Compare in the biomass boiler calculator and the heating cost comparison.

Air quality caveat. Small-scale wood burning is a major source of fine particulate matter (PM2.5) in Europe. In some countries it is the largest single source, according to the European Environment Agency. Modern certified appliances emit far less than old stoves, but in towns and cities heat pumps or district heating are cleaner.

The carbon accounting debate

At the chimney, wood releases more CO₂ per kWh than coal, because it holds less energy and more moisture: roughly 0.35–0.40 kg CO₂/kWh of fuel, against 0.34 for hard coal and 0.20 for gas. National inventories count bioenergy as zero at the stack. The emissions are meant to show up in the land-use sector instead, on the assumption that regrowing plants take the carbon back.

Whether they take it back fast enough to matter for the climate depends on the feedstock:

The European Commission’s Joint Research Centre (2021) reviewed the pathways and found that only some forest bioenergy cuts emissions within a few decades, mostly the kind that uses residues which would otherwise decompose quickly. Large-scale pellet imports for power, such as North American wood shipped to the UK’s Drax power station, remain controversial.

Biofuels for transport

Indirect land-use change (ILUC), where biofuel crops push food production onto forest land, can wipe out the savings. That is why the EU’s Renewable Energy Directive caps crop-based fuels at 7% of transport energy and phases out high-ILUC feedstocks like palm oil by 2030. For cars, electrification uses far less land: a hectare of solar panels charging EVs covers roughly 50–100 times more kilometres than a hectare of energy crops turned into biofuel. Biofuels make most sense for aviation (sustainable aviation fuel), shipping and the existing fleet.

BECCS: negative emissions

Bioenergy with carbon capture and storage captures the CO₂ from burning biomass and stores it underground, so net emissions go negative. Many IPCC pathways that limit warming to 1.5 °C lean heavily on BECCS. Actual deployment is tiny (a few Mt CO₂/yr, mainly from US ethanol plants), and BECCS at scale would need enormous areas of land.

Choosing biomass responsibly: a checklist

Thinking about biomass for a home, farm or business? These questions sort low-impact projects from problem ones:

• Where does the fuel come from? Prefer certified fuels (ENplus for pellets, FSC or PEFC chain of custody) and local residues: sawmill by-products, thinnings, arboricultural waste, straw surpluses. Ask suppliers for the feedstock mix.
• How dry is it? Wet wood burns poorly and smokes. Firewood should be below 20% moisture, which takes about two years of covered seasoning for hardwoods. Pellets are always dry.
• Is the appliance certified? Look for Ecodesign-compliant stoves and boilers with low particulate emissions, and an electrostatic precipitator for larger boilers in populated areas.
• Is there a better alternative? In towns with gas or a good grid connection, a heat pump usually emits less and doesn’t pollute the street. Biomass makes most sense off the gas grid, in rural areas with local fuel, or for high-temperature process heat.
• For digesters: is there a steady feedstock and a use for the heat? Plants that run on purpose-grown maize score worse on climate and land use than those fed with manure and waste. Plants that dump their CHP heat throw away about half the energy.
• What happens to the digestate and ash? Properly managed digestate replaces mineral fertiliser, but leaky storage can emit ammonia and methane. Wood ash can go back to forests or fields where conditions suit.

Getting these right rarely costs much extra, and it decides whether a project actually cuts emissions.

Bottom line

Bioenergy is a family of technologies. Some are excellent, like biogas from manure and food waste or residues burned for local heat. Others do harm, like crop biofuels that drive deforestation or mature forests burned for power. The best projects use waste streams, avoid methane and serve sectors with few alternatives, such as high-temperature industry and aviation. For home heating, check the numbers in the biomass boiler calculator. Farms and food processors can estimate gas, power and heat with the biogas calculator. Compare bioenergy’s role in each country on the country pages.

Figures in this guide are typical ranges drawn from the sources above; your own numbers depend on location, prices and equipment. Use the linked calculators for site-specific estimates.