New permitting rules for anaerobic digestion

Anaerobic digestion is not a low-risk activity, but we have a low-risk approach to regulation,” said Mr Leberman. “The risk is managed through the size of the AD, waste types and location. At the small-scale end, farmers may be able to register an exemption. Otherwise, a standard rules permit may be used, or failing that, a bespoke permit.

“As with all our exemptions, read the Environment Agency guidance and either register online or download the exemption form and register by post.”

Exemptions (no need for an EA permit)

T24 – Agricultural premises:

  • Wastes limited to plant matter, farmyard manure and slurry only
  • Storage and treatment limit of 1,250cu m at any one time
  • Burner limited to a net thermal input of 0.4MW

T25 – Non-agricultural premises:

  • Wastes limited to plant matter, farmyard manure and slurry, as well as some food and packaging wastes
  • Storage and treatment limit of 50cu m at any one time
  • Burner limited to a net thermal input of 0.4MW.

For AD plants that don’t meet the exemptions requirements, the next step is the standard rules approach to permitting – this is set to change by 7 January 2013, said Mr Leberman.

“If you cannot comply with the exemptions, we then move on to the standard rules approach. A standard rules permit is much cheaper and easier to get than a bespoke permit,” he said.

There are three sets of standard rules and permits: digestion of manures and slurries on farms; digestion of a wider range of food and biodegradable waste and storage of waste digestate at locations away from the AD site.

Changes to standard rules and permits

Two sets of standard rules are being introduced in January:

  • Waste throughput lower than 100t/day – waste standard rules
  • Waste throughput of more than 100t/day – installation standard rules


  • Waste throughput capped at 100,000t/year
  • Combustion units capped at 5MW net rated thermal output

Current costs:

  • Permit application fee – £1,590
  • Subsistence fee – £1,540 a year for on-farm plants taking farm water only, but this will change

With the new standard rules comes a revised set of risk criteria – an AD facility must not be within 10m of a watercourse, a groundwater source protection zone 1 or a specified air quality management area.

In addition, the gas engine stack must be a minimum of 3m in height and not located within 500m or 200m – depending on which SR you are using – of an ecologically designated site. For stacks that do not have an “effective stack height” of 3m, the stack must be at least 200m from any nearby house or public building.

“Failing the standard rules, you will need to apply for a bespoke permit. This allows us to scrutinise your application before we issue a permit. The costs are going to go up considerably and the determination time can take up to 13 weeks,” said Mr Leberman.

Bespoke permits

  • Application requires additional information about the criteria you cannot meet and how you intend to control the associated risks
  • Environment Agency is required to put the application out to statutory consultation
  • Charges are based on the operational risk appraisal and depend upon complexity, inputs and emissions, location and operator management systems and performance.

With regard to digestates, manures and slurries are considered fully recovered once they have been digested and are not subject to further permitting controls. However, all other digestate is considered a waste and subject to permitting, said Mr Leberman.


  • Digestate may be spread to land in accordance with a standard rules permit
  • One-off permit application charge of £700
  • Additional deployment cost based on risk and distance criteria: £450 for low-risk areas and £900 for high-risk areas per 50ha
  • Online applications may be lodged for each deployment authorisation.
  • Find more information on the Environment Agency website at or call EA customer services on 03708 506 506.

More on this topic

Environmental permit next hurdle for Welsh farmers

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