Environmental guidance for your business in Northern Ireland & Scotland

Biomass and anaerobic digestion

Biomass and anaerobic digestion

Biomass energy accounts for around 85 per cent of the UK's renewable energy supply. Biomass refers to organic materials, such as wood, straw and energy crops, which can be used to generate electricity, heat and motive power. The energy is released by burning and fermentation.

You can only use certain biomass burners in smoke control areas.

Defra: List of exempt appliances

If you are an appliance manufacturer, importer or distributor, you can apply for an exemption on the Defra website.

Defra: Applications for exemption

The payback period for biomass systems is generally five to 12 years, though this can be significantly shorter if free waste wood is available.

Biomas systems can be particularly effective when part of a Combined Heat and Power (CHP) system.

SEPA has produced guidance on the regulatory controls that apply to biomass burning to produce energy. This deals with issues relating to the PPC regulations, Waste incineration directive and Waste Management Licensing.

SEPA: Permitting guidance for Biomass Combustion

Anaerobic digestion is another method of converting biomass into energy. In this process, organic material is broken down by bacteria, in the absence of oxygen, to create methane-rich biogas. This can then be burned to generate heat and electricity. The solid waste from the process is called digestate and can be used in a similar way to compost.

The payback periods for anaerobic digestion plants vary widely, but could be between five and ten years.

Advantages of biomass energy and anaerobic digestion

  • You can use waste by-products to generate energy and reduce your waste disposal costs.
  • It can be used in combination with a combined heat and power plant to generate both electricity and heat.
  • Burning biomass fuels releases lower net carbon dioxide emissions than burning coal and gas.

Disadvantages of biomass energy and anaerobic digestion

  • You need to control emissions from burning biomass materials to prevent local air pollution. Any system you install must comply with legislation such as the Clean Air (Northern Ireland) Order.
  • Storing biomass fuels can require a large amount of space.
  • It can be difficult to find a secure supply of fuel. If you intend to use by-products from your business you must ensure that suitable quantities will be available.
  • If you're having fuel delivered, you'll need to consider the environmental impact of fuel transportation.

Complying with waste controls

If you anaerobically digest waste to generate gas for heat or electricity you must have a pollution prevention and control permit or waste management licence.

Anaerobic digestion

You must comply with waste regulations including the duty of care. If you are collecting and transporting other people's waste you will need a waste carriers licence.

Duty of care – your waste responsibilities

Quality protocol in Northern Ireland

The Northern Ireland Environment Agency (NIEA) and the Waste & Resources Action Programme have created a quality protocol for anaerobic digestate. If you follow the protocol, you can produce a high quality digestate which can be sold without waste handling controls.

For example, if it is not classed as a waste, you do not need to transport it using a waste carrier or with a waste transfer note.

NIEA: Regulatory position statement on the production of anaerobic digestate

NIEA: Quality protocol for the production and use of quality compost


You can use digestate without waste management controls if it complies with the Scottish Environment Protection Agency (SEPA) position statement.

SEPA: Regulation of outputs from Anaerobic Digestion processes

Animal by-products

If you use parts of animals, products of animal origin or food and catering waste you must comply with animal by-product controls.

Animal by-products

Prevent odour from your anaerobic digester

You must prevent your anaerobic digester causing an odour nuisance to your neighbours. You must design your digester, storage areas and delivery areas to minimise the escape of odour and liquids.

Reduce your digester's operating temperature and use a two-step digestion process by pasteurising your material first, to reduce odour problems.

Noise, odour and other nuisances

Further information

The Carbon Trust: Biomass Heating

Anaerobic Digestion Portal: AD, digestate and biogas

Defra: List of exempt biomass appliances

In this Guideline

Benefits of using renewable energy

Generating income from renewable energy

Renewable energy considerations

Wind energy

Biomass and anaerobic digestion

Solar energy

Geothermal energy and ground source heat pumps

Hydroelectric power

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NIEA - Apply online

SEPA - Application forms