Biogas is a methane-rich gas made when microorganisms break down organic material without oxygen. It can be sustainable when it captures methane from waste that would otherwise release it and when the facility controls leaks; the answer depends on the feedstock, its alternative fate and how the gas is managed.
What is biogas?
Biogas is a mixture of gases created through anaerobic digestion: microorganisms break down organic matter in an oxygen-free environment. Typical biogas contains 45% to 75% methane by volume, with carbon dioxide and small amounts of other gases. Its composition varies with the feedstock and production route. The International Energy Agency (IEA) explains biogas production and composition.
Common feedstocks include manure, food and other organic waste, sewage sludge, and municipal waste decomposing in landfills. Biogas can be produced in airtight digesters, recovered from landfill gas systems, or generated as sewage sludge is digested at wastewater treatment plants.
How is biogas made and used?
Production and upgrading
In a digester, organic material is held without oxygen so microbes can break it down and release gas. The resulting raw biogas contains methane as well as carbon dioxide, water and other contaminants; it is not the same as pipeline natural gas.
#1 Best Overall
When raw biogas is cleaned to remove carbon dioxide, water and contaminants, the resulting gas is called biomethane, also known as renewable natural gas. Biomethane is mostly methane. Its use in natural-gas equipment or networks depends on adequate processing and compatible local infrastructure. The U.S. Environmental Protection Agency describes renewable natural gas feedstocks and uses.
Energy uses
- Biogas: Can be burned directly for heat or used to generate electricity.
- Biomethane: Can be used as vehicle fuel, for electricity and heat, or as a feedstock for bio-products, provided it is adequately upgraded for the intended use.
Is biogas sustainable?
Sometimes. Capturing methane from manure, food waste or other material that would otherwise decompose and release methane can reduce emissions. But the benefit depends on what would have happened to the feedstock without the project, how the plant operates, and whether methane escapes during digestion, digestate storage or gas upgrading.
Feedstock and its alternative fate
Waste and residues such as manure, food waste and sewage sludge can make use of material that already needs treatment. Their climate value depends in part on whether they would otherwise emit methane and on what happens to the remaining digestate. Dedicated energy crops raise additional land-use questions and can carry fertilizer-related emissions. The IEA says those effects should be considered when evaluating crop-based pathways. The IEA’s sustainability assessment discusses feedstock choices and their impacts.
Methane leakage
Methane is the energy-bearing part of biogas, but releases can undermine or erase the climate advantage over natural gas. The IEA’s 2025 outlook reports estimated methane emissions in a range of 2% to 5.5% of output for biogas and biomethane plants. In its discussion of project types, it separately estimates leakage at 2% to 5.5% for agricultural biogas plants and near 8% for wastewater treatment plants. These are reported estimates, not a measured rate for every facility. The IEA’s 2025 outlook covers methane leakage and project issues.
Rank #3
- Used Book in Good Condition
Leak detection and repair, covered digestate storage, and combustion of off-gases during biomethane upgrading can help limit releases. The IEA states: “Concerted application of best practices for methane management is essential to underpin the environmental case for biogases.”
How to assess a project
The word “biogas” alone does not establish a project’s climate performance. For a useful assessment, ask:
Rank #4
- Used Book in Good Condition
- What material goes into the system, and what would have happened to it otherwise?
- How are methane leaks detected and repaired, and is digestate stored under cover?
- Is the gas used locally as biogas, or upgraded to biomethane—and what energy and infrastructure does that require?
- If crops are grown for the digester, how are fertilizer and land-use effects accounted for?
How much biogas is produced?
The IEA’s 2025 outlook says biogas accounts for around 3% of total modern bioenergy production. This is a share of modern bioenergy, not of all energy. The report also estimates nearly 1,000 billion cubic metres equivalent (bcme) of sustainable production potential; that figure is an estimate of potential, not current output. The IEA’s 2025 report provides these production and potential figures.
Can you make biogas at home?
Household biogas digesters exist. For example, HomeBiogas describes a system that converts food waste or manure into cooking gas and liquid fertilizer. Its owner’s manual says performance is affected by environmental conditions and can vary by location and ambient temperature. This manufacturer information does not establish how much gas or fertilizer a particular household will produce. HomeBiogas provides information about its household biogas system.
Free tools Windows power users keep installed
One-click scans. No signup required.
A home system is specialized equipment, not a guaranteed fit for every property. Before considering one, assess the available feedstock, operating conditions, space and intended use of the gas and digestate.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
