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Guide to the Green Gas Support Scheme

The Green Gas Support Scheme is a key part of the UK government’s strategy to reduce carbon emissions from the national gas grid. Today, over 99% of the gas supplied to homes and businesses is fossil fuel-based, generating significant carbon emissions when used by heating systems.

The Green Gas Support Scheme aims to change that by encouraging anaerobic digestion facilities in Britain to produce renewable biomethane and inject it into the grid as a substitute for natural gas.

Last year, the scheme supported the injection of 29 million cubic metres of green gas into the grid and is expected to grow significantly over the coming year.

This guide explains everything you need to know about the GGSS:

• What is the Green Gas Support Scheme?
• Current Green Gas Support Scheme tariffs
• How the Green Gas Support Scheme works
• Participants in the Green Gas Support Scheme
• Who can apply for the Green Gas Support Scheme?

What is the Green Gas Support Scheme?

The Green Gas Support Scheme (GGSS) is a government incentive designed to encourage biomethane production. Biomethane is a sustainable alternative to natural gas that can be injected into the gas grid to make gas supplies greener.

The GGSS supports investment in anaerobic digestion facilities that produce biomethane for the grid by:

• Receiving organic waste material such as food waste or agricultural residues.
• Storing the waste in a sealed tank with no oxygen (this is what “anaerobic” means).
• Maintaining conditions that encourage bacteria to break down the waste and produce biogas.
• Using a biogas upgrading unit to purify the biogas, creating biomethane.
• Compressing the biomethane and injecting it into the gas grid.

The GGSS requires that most of the organic material fed into the digester comes from waste products rather than purpose-grown energy crops, to ensure the process is genuinely sustainable.

The GGSS provides an incentive by paying operators for each kWh of biomethane injected into the grid.

Current Green Gas Support Scheme tariffs

The Green Gas Support Scheme tariffs are the rates, per kWh of injected biomethane gas, that participants receive under the scheme.

The table below shows the current tariff rates offered under the GGSS, based on the start date of each tariff:

Source: Ofgem Green Gas Support Scheme tariff table

In August 2025, the government announced that the above rates would remain unchanged from 1 October 2025.

How the Green Gas Support Scheme works

Participants in the GGSS receive quarterly tariff payments from the energy regulator Ofgem for 15 years.

The tariffs are paid per kWh of biomethane injected into the grid, based on three tiers, with a decreasing subsidy as volumes increase. The GGSS subsidy is limited to 250,000 MWh per participant per year.

Payments under the GGSS are a direct government subsidy and are not for the purchase of the gas. GGSS participants sell the biomethane they inject into the grid on the wholesale gas market, receiving a separate payment from energy suppliers.

Funding for the Green Gas Support Scheme

The GGSS is funded by licensed domestic and business gas suppliers, who recover the fees from customers through a daily standing charge called the Green Gas Levy.

Each supplier pays the Green Gas Levy quarterly to Ofgem, which then distributes the funds to registered participants in the GGSS.

Find out more in our full guide to the Green Gas Levy.

Compatibility with other support schemes

The GGSS is not compatible with most other government renewable energy support schemes. This is to prevent double funding and to ensure the fair use of public money.

Here are some key considerations regarding GGSS compatibility:

• Renewable Heat Incentive (RHI): The GGSS replaced the RHI for new biomethane-to-grid projects.
• Green Gas Certification Scheme: Green Gas Certificates can still be generated and sold to business energy suppliers.
• Renewable Transport Fuel Certificates (RTFCs): Not compatible. Gas supported under the GGSS, if later used for transport, cannot also benefit from the RTFC scheme.
• Contracts for Difference (CfD): The CfD scheme is designed to support renewable electricity generation, not gas production.

Participants in the Green Gas Support Scheme

As of October 2025, there are seven participants in the Green Gas Support Scheme. The UK government’s Business Subsidy Register provides details of these participants.

The table below summarises the publicly available information about each participant.

Who can apply for the Green Gas Support Scheme?

The Green Gas Support Scheme is open to anyone investing in a new anaerobic digestion facility that will produce biomethane for injection into the gas distribution grid.

It’s important to note that the application process is lengthy, costly, and only realistically viable for large-scale projects.

Smaller anaerobic digestion plants are more likely to benefit from the Smart Export Guarantee scheme by using biogas onsite to generate renewable electricity, which can then be exported into the local distribution network operator grid.

The section below summarises the eligibility criteria for participation in the GGSS.

Business and project eligibility

To participate in the GGSS, you must invest in a new anaerobic digestion facility located in Great Britain that will produce biomethane for injection into the gas grid.

The anaerobic digestion facility must meet the following sustainability criteria:

• Injected biomethane must have lifecycle emissions of less than 24g CO₂ per megajoule (MJ).
• The feedstock must come from sustainably managed land.
• The biomethane must not be generated from landfill gas.

These low-emission requirements for biomethane restrict the types of feedstock to sustainable sources only.

Feedstock sustainability criteria

The GGSS lifecycle emissions criteria are assessed based on the average emissions from the feedstock mix used, allowing participants to use a combination of fuels.

In effect, the rules require the use of low- or negative-emission feedstocks. The table below provides an overview of the relative emissions associated with different types of feedstock:

The rules significantly restrict the use of purpose-grown crops such as maize and wheat, as these compete with domestic food production.

Sustainability reporting requirements

Participants in the GGSS must adhere to strict reporting guidelines to continue receiving payments under the scheme.

The mandatory reporting requirements include:

• Feedstock reporting: Detailed records of the feedstocks used, including type, source, and quantity, must be maintained. These must be reported to Ofgem regularly via a Fuel Measurement and Sampling questionnaire.
• Sustainability declaration: Participants must periodically calculate the emissions from injected biomethane and declare that the fuel meets the required sustainability criteria.
• Sustainability audit: An independent audit must be arranged annually, and the report submitted to Ofgem.

How to apply for the Green Gas Support Scheme

The application process for the Green Gas Support Scheme consists of three distinct phases. This section outlines the information required and the steps involved in each stage.

The GGSS remains open to new applicants until 31 March 2028.

Stage 1 – Apply for Provisional Tariff Guarantee Notice

The first stage of the GGSS application process is to apply for a Provisional Tariff Guarantee Notice (PTGN).

A PTGN guarantees a specific tariff rate per kWh of gas injected into the grid, subject to the successful completion of the second and third stages of the application process.

Stage one applicants must have a detailed business plan to construct their new anaerobic digestion facility and are required to have:

• An agreement from the local grid for a new business gas connection to inject the biomethane that the project will generate.
• Planning permission for the anaerobic digester and associated production processes.
• A projected date on which biomethane injection will commence.
• The expected initial capacity of the project.
• The location of the anaerobic digester and injection point.

Applicants must be able to secure financing within three weeks of receiving a Provisional Tariff Guarantee Notice. This typically means that stage one applicants will already have begun negotiating investment or loan agreements for their project.

Stage 2 – Financial close

Stage two of the application process begins when Ofgem issues a Provisional Tariff Guarantee Notice (PTGN).

The PTGN requires the applicant to demonstrate that sufficient funds are available to complete the project’s construction within three weeks of the notice being issued. This is typically evidenced by a signed investment or loan agreement.

Ofgem also requires an independent auditor to verify that the funds are available and committed to the proposed project.

Additional evidence may be requested by Ofgem at this stage, including construction contracts and land ownership or lease agreements.

A tariff guarantee is formally awarded to the project if the stage two application is accepted.

Stage 3 – Commissioning and final application

Upon completion of stage two, Ofgem will issue a Tariff Guarantee Notice (TGN), which will specify:

• The guaranteed tariff rates the project will receive for the gas injected.
• The deadline by which biomethane injection must commence.
• A description of the equipment used to produce biomethane.
• Any other conditions attached to the guarantee.

The deadline for commencing biomethane injection is typically six months from the expected injection date provided in stage one.

Stage three of the application process confirms that the project has been constructed and that gas injection has commenced.

The application must include sufficient information for Ofgem to verify that the scheme requirements have been met for the anaerobic digestion facility. This includes:

• Construction cost data and details of equipment purchased.
• Fuel measurement and sampling processes.
• Business gas meter details used to measure injection volumes.
• Feedstock information outlining the organic material used to produce biomethane.

The environmental goals of the Green Gas Support Scheme

The Green Gas Support Scheme provides a significant financial incentive for companies to invest in producing green gas and injecting it into the national grid.

In this section, we explain the environmental and wider objectives of the scheme.

Lower emissions from gas consumption

Gas boilers in homes and businesses account for around 30% of the UK’s greenhouse gas emissions.

Injecting green biomethane is one of the few practical methods available to reduce emissions associated with gas supply.

Biomethane produced from waste products can achieve up to an 80% reduction in emissions compared with natural gas.

Promotes a circular economy

The GGSS criteria effectively require the use of feedstock derived from waste products, helping to create a circular economy for organic materials.

In particular, the following waste materials are most commonly used under the scheme:

• Food waste
• Manure and slurry
• Agricultural residues

Enhances energy security

Biomethane injected under the GGSS is produced on mainland Britain and serves as a direct alternative to natural gas. Britain currently imports large volumes of natural gas from overseas via the Langeled pipeline and through LNG imports to meet domestic demand.

Encouraging biomethane production reduces the need for natural gas imports, helping to protect the country from wider geopolitical events that affect domestic and business gas prices.

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