This assessment considers over 30 types of feedstocks for biogases. They can be broadly grouped together as crop residues, animal manure, biowaste and woody biomass. We assess feedstocks that can be processed without direct competition with food for agricultural land or animal feed, and that do not have any other adverse sustainability impacts.

Biogas and methane yields are key indicators of how suitable a feedstock is for energy production. Biogas yield refers to the total volume of gas produced from a feedstock through anaerobic digestion, primarily methane (CH₄) and CO₂. Methane yield, by contrast, accounts only for the methane portion, which is the component usable as fuel. For this report, we considered the methane yield per tonne of dry matter for a range of different feedstocks.

Emerging market and developing economies account for 80% of the global potential for biogases, which is concentrated in countries where the agricultural sector plays a prominent role in the economy. India, Brazil, and China lead the way with high biogases potential from cereal crop residues, sugar crop residues, and manure respectively, derived from existing large-scale agricultural industries.  

The key considerations affecting the economics of a biogas and biomethane plant are its size, feedstock composition and quality, and locational factors such as collection radius, access to grids, roads and other supporting infrastructure. 

The main cost component of a biogas project is the anaerobic digester. Capital expenditure for biogas plants demonstrates significant economies of scale, with larger facilities offering lower costs per unit of production capacity. Landfill gas requires lower upfront investment in the digestion process but additional capital and operational expenditures are required for the gas collection infrastructure.  

Biogas and biomethane projects tend to have relatively high ongoing operating expenses compared with other energy sources. Expenses are associated with pre-treatment and processing as well as energy required for onsite equipment such as digesters and upgrading facilities. The economics of feedstock procurement also vary considerably, depending on the source material, spatial density and local market conditions. 

Fully developing the assessed potential for biogases requires a mix of different biodigesters, depending on the scale, diversity and collection radius of available feedstocks. For example, animal manure has a high moisture content and is thus costly to transport, meaning the economical collection radius is typically 10 km from a centralised biodigester. For crop residues, areas with dense and high-yielding crop residues can support large-scale plants – thereby enlarging the radius for collection (up to 50 km) and potentially also lowering the cost through economies of scale. Production from large-scale biodigesters can be up to 40% cheaper than from small-scale digesters.

Biomethane is competitive with other low-emissions fuels in sectors such as maritime transport (where electrification options are limited), in industries that use high-temperature processes or where gaseous fuels are required as a feedstock. Such sectors can use biomethane without major modifications to existing equipment. 

Power generation is a key end-use sector for biogases, where increased biogas production or stored biogases can be leveraged to provide power system flexibility. Biomethane plants can operate in a flexible manner and so provide balancing and other ancillary services to the electricity network. For seasonal flexibility, gas-fired power plants are still one of the few readily available options. The use of biomethane would enable this role to be performed with lower emissions than using natural gas. The levelised cost of electricity of power plants fired by natural gas is around 15-65% lower than that of biomethane, but a CO2 price of USD 100/t CO₂ would put biomethane power plants in the same price range.  

Biogas is one of several modern fuels and technologies that can provide clean cooking. The increased use of these fuels and technologies would mean lower rates of premature deaths related to indoor and outdoor air pollution, as well as positive socio-economic benefits. Small biodigesters, which are suitable for households with a few cows, are a clean cooking solution primarily for rural areas. 

The main economic barrier for biogas as a clean cooking solution is the relatively high upfront cost of the biodigester. However, on a total cost-of-ownership basis, biodigesters have an advantage s they have low or zero fuel costs.  

Biogas upgrading results in a highly concentrated stream of biogenic CO2. This can be used as an input into low-emissions fuels production (when combined with renewable or low-emissions hydrogen) or captured and stored. 

In large biogas upgrading plants, which benefit from economies of scale, the concentrated stream of CO2 can often be captured for around USD 15/t CO₂ to USD 30/t CO₂. This is much lower than the more dilute streams produced by the steel and cement industries and thermal power plants (which often cost USD 40/t CO₂ to USD 110/t CO₂), and by direct air capture.