Consultation on modernising environmental permitting for industry
Non-waste anaerobic digestion
Anaerobic digestion (AD) is a biological process that breaks down organic matter, such as food waste and agricultural residues, in the absence of oxygen, to produce biogas and a nutrient-rich digestate. The biogas can then be upgraded into biomethane, a low carbon gas that can be injected to the gas grid as a direct replacement for natural gas. Biomethane production from AD has an important role to play in the transition to net zero, decarbonising the gas supply, reducing reliance on fossil fuels, and increasing our country’s energy security. It has potential across a variety of end uses, including being a flexible fuel to support decarbonisation across heat, buildings, industry, power generation, transport, agriculture, and hydrogen production.
AD has the potential to provide significant environmental benefits. AD sites can provide an effective treatment method to process organic wastes and residues that would otherwise be sent to landfill. The AD process captures methane - a potent greenhouse gas - that would otherwise be released to the atmosphere. The by-product of AD, a nutrient-rich digestate, when managed well, can also contribute to the circular economy by providing a natural alternative to chemical fertilisers. Furthermore, biomethane production has the potential to deliver negative emissions, through carbon capture technology both at the point of production and point of combustion.
In Great Britain, the AD sector is supported by government initiatives such as the Green Gas Support Scheme which provides tariff-support for biomethane produced via AD and injected into the gas grid. The government is currently considering options for post-GGSS support for the sector.
As the AD sector grows, it is important to ensure that AD sites continue to be properly managed. If poorly operated, AD sites can pose serious environmental and health and safety concerns, causing pollution of air, land and water through fugitive emissions, such as methane, and land and water pollution from accidents which can damage the environment. The EA has documented numerous incidents at AD plants, including pollution, containment failures and fires, highlighting the need for regulatory oversight of the AD process and clear industry standards. Research from the Methane Emissions from Anaerobic Digestion (MEAD) study also found evidence of fugitive methane emissions from both waste-fed and non-waste fed AD sites which highlights the risk of emissions from these sites when poorly managed, emphasising the importance of effective monitoring and operational controls.
AD facilities using waste feedstocks (for example, commercial or retail food waste, wastewater), are subject to environmental permitting, which sets controls on emissions and site operations, including the techniques used, waste management and environmental safeguards. These regulations help prevent pollution, manage risks and ensure safe operation. However, regulation does not currently apply consistently across the sector.
AD facilities processing non-waste feedstocks, such as those using purpose-grown crops or crop residues as feedstock, fall outside the permitting regime. Despite using the same technologies and posing similar environmental risks, they are not required to meet the same standards, although some plants do adhere to these standards on a voluntary basis. This weakens environmental protection and creates inconsistencies in industry standards and the AD regulatory landscape causing market distortions. It also limits the potential of AD infrastructure, as co-digestion of waste and non-waste materials is underutilised.
We are minded to consult on making the anaerobic digestion of non-waste feedstocks a Part A1 activity of the EPRs, requiring sites that meet certain thresholds to hold an environmental permit. Currently, waste-fed AD facilities are regulated under the EPR and must operate under either an exemption, a standard rules permit or a bespoke permit.
Standard rules permits apply to lower-risk waste treatment scenarios, for example, AD facilities treating up to 100 tonnes of waste per day. Larger AD plants processing over 100 tonnes per day are classed as installations under the IED and require a bespoke environmental permit. Smaller AD operations treating waste can operate under Registered Exemptions, subject to limits including the volume of waste stored or treated (for example, up to 1,250 cubic metres for on-farm sites and 50 cubic metres for non-farm sites) retention time and thermal input.
Applying a similar permitting threshold to non-waste AD facilities would help close this regulatory gap. A consistent permitting approach would strengthen environmental protection, standardise requirements, and support fairer competition across the sector. A consistent approach would also present an opportunity for non-waste AD plants to more easily demonstrate that they are working to an acceptable environmental standard.
This change would align with an EA review updating standards for the AD industry, helping to establish a more cohesive regulatory framework and ensure the same environmental rules and operating standards apply across the sector.