Guidance

Using back up flares at exempt anaerobic digestion plants: RPS 120

Updated 9 December 2025

Applies to England

This regulatory position statement (RPS) does not change your legal requirement to:

• have an environmental permit where one is required

• register an activity as exempt where you are required to do so

However, the Environment Agency will not normally take enforcement action against you if you do not comply with these legal requirements provided that:

• your activity meets the description set out in this RPS

• you comply with the conditions set out in this RPS

In addition your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:

• cause a risk to water, air, soil, plants or animals

• cause a nuisance through noise or odours

• adversely affect the countryside or places of special interest

Activity this RPS applies to

This RPS applies to anaerobic digestion plants which are operated under, and in accordance with, a T24 or T25 waste exemption.

This RPS only applies if you use backup flares to:

• prevent the release of unburnt biogas and biomethane emissions to the environment, for example from pressure relief valves

• protect the integrity of the plant during an emergency

• burn gas if the appliance used for gas to energy cannot operate due to a breakdown, or during routine maintenance

Conditions you must comply with

You must:

• only operate the flare for the minimum period of time needed to resolve the maintenance or emergency issue – prolonged releases to atmosphere are not allowed

• record the date, time (including duration of use) and reason you carried out flaring

• keep records for 2 years from the date of the last use of the RPS to show that you have complied with this RPS and make these records available to the Environment Agency on request

Things to note

The Environmental Permitting (England and Wales) Regulations 2016 list 2 exemptions for the anaerobic digestion of waste:

• T24 waste exemption: anaerobic digestion at premises used for agriculture and burning resulting biogas

• T25 waste exemption: anaerobic digestion at premises not used for agriculture and burning resulting biogas

Under these exemptions operators can only burn gas produced in a specified appliance or more than one appliance with a net rated thermal input of less than 0.4 megawatts (MW) used for producing energy. There is no provision within the exemptions for using backup flares to dispose of biogas or biomethane.

All anaerobic digestion plants operating under these exemptions must have a standby flare available or a means to use and combust biogas and biomethane.

This RPS relates to an activity that the Environment Agency considers is potentially suitable to be an exemption under the Environmental Permitting (England and Wales) Regulations 2016. A change in law would be required for this.

When you must check back

The Environment Agency will review this RPS by 1 October 2028.

The Environment Agency can withdraw or amend this regulatory position before the review date if they consider it necessary. This includes where the activity that this RPS relates to has not changed.

You will need to check back from time to time, including at and before the review date, to see if this RPS still applies.

This RPS remains in force until it is removed from GOV.UK or is otherwise identified as having been withdrawn.

You can subscribe to email updates about this RPS. These will tell you if the RPS has changed and when it has been withdrawn.

If you cannot comply with this RPS

If you operate under this RPS but can no longer comply with it, you must:

• stop the activity to which this RPS relates
• tell the Environment Agency immediately by contacting enquiries@environment-agency.gov.uk with RPS 120 in the subject

Contact the Environment Agency

If you have any questions about this RPS, email enquiries@environment-agency.gov.uk with RPS 120 in the subject.