Environment Agency Briefing Note: Medium Combustion Plant (MCP) and Specified Generators (SG) – England Only

06 March 2026

To comply with the requirements of the Environmental Permitting Regulations (EPR), Schedule 25A & 25B you need a permit from the Environment Agency (EA) for the following:

  • New standalone MCPs between 1-50MWth (before it is commissioned)
  • Existing standalone MCPs between 5-50MWth
  • Tranche A and B specified generators (permitting date requirement varies)

If you need a permit and have not already submitted an application, you should do this as soon as possible to avoid enforcement action in line with the Environment Agency’s enforcement and sanctions policy. If you want to report illegal operations, please contact enquiries@environment-agency.gov.uk or call us on 03708 506 506.

Please note: The following parts of this briefing note are technical in nature and may require background knowledge of MCP&SG regulations. If you are new to the requirements, then we recommend that you read our guidance pages here first: Medium combustion plant and specified generator regulations – GOV.UK

Standard Rules (SR) Permit for New and Existing Low Risk Stationary MCPs and Tranche B Specified Generators

Standard rules permits are available for certain low risk MCP and SG operations, these are the quickest and cheapest option available.

The standard rules sets available to apply for are listed here.

To apply for a SR permit you must be able to meet the rules and criteria set out in the permit, if you cannot you need to apply for a bespoke permit.

The latest version (v7.3, published 26 February 2026) of the MCP and SG standard rules excel application form located here.

Following consultation with stakeholders we have recently published some amendments to the standard rules sets and associated generic risk assessments for MCP and SG, the changes are summarised below and apply to all current standard rules permit holders from the 26th February 2026:

Amendments to SR 2018 No 1

  • Hydrogen has been added as a new fuel type on this rule set with corresponding criteria and emission limit values (ELVs) including for blends with natural gas.
  • Decarbonisation readiness conditions have been added.
  • We have added Marine Conservation Zones (MCZ) under the meaning of protected habitats.
  • Tables 3.1 and 3.2 have been consolidated into one table.
  • Reference to TGN5 have been replaced with the correct reference to our guidance on the low-risk monitoring method and MCERTS monitoring has now been included as a monitoring option.
  • There are various updates to the interpretation section to improve understanding.

Amendments to SR 2018 No 3

  • Following consultation, amendments have been made to Table 2.3 operating technique (e) wording.
  • The rule set has also been withdrawn for new applications and is now only relevant to existing permit holders.

Amendments to SR 2018 No 4

  • Hydrogen has been added as a new fuel type on this rule set with corresponding criteria and emission limit values (ELVs) including for blends with natural gas.
  • Gas oil substitutes have been added as a fuel type with corresponding criteria.
  • We have added Marine Conservation Zones (MCZ) under the meaning of protected habitats.
  • Decarbonisation readiness conditions have been added.
  • Tables 3.1 and 3.2 have been consolidated into one table.
  • Reference to TGN5 have been replaced with the correct reference to our guidance on the low-risk monitoring method and MCERTS monitoring has now been included as a monitoring option.
  • There are various updates to the interpretation section to improve understanding.

Amendments to SR2018 No 7

  • Hydrogen has been added as a new fuel type on this rule set with corresponding criteria and emission limit values (ELVs) including for blends with natural gas.
  • Gas oil substitutes have been added as a fuel type with corresponding criteria.
  • Caps, cowls, and non-vertical stacks are now permitted in circumstances where the installation of vertical, uncapped stacks is not practicable.
  • We have updated wording around use of this rule set in an air quality management area (AQMA) where there is a relevant air quality plan.
  • MCERTS monitoring has now been included as a monitoring option.
  • There are various updates to the interpretation section to improve understanding.

Amendments to SR2022 No 9

  • Hydrogen has been added as a new fuel type on this rule set with corresponding criteria and emission limit values (ELVs) including for blends with natural gas.
  • Gas oil substitutes have been added as permitted back-up fuel with corresponding criteria.
  • Caps, cowls, and non-vertical stacks are now permitted in circumstances where the installation of vertical, uncapped stacks is not practicable.
  • We have updated wording around use of this rule set in an air quality management area (AQMA) where there is a relevant air quality plan.
  • MCERTS monitoring has now been included as a monitoring option.
  • There are various updates to the interpretation section to improve understanding.

Removal of rule set SR2018 No 2 for new applications

This rule set has now been withdrawn from use by new applicants, only existing operators with this permit can continue to use this rule set. It has not changed since it was last published on the 13 September 2018.

Full removal of rule sets SR2018 No 5, 6, 8 & 9

From the 26 February 2026 these standard rules are no longer available to any operators. All operators who had one of these permits have already been varied to a bespoke permit instead.

For more information about the reasons for these changes, you can view the relevant consultation response documents for decarbonisation readiness and another on the wider changes relevant to MCP and SG standard rules.

We do not believe that the changes should impact existing permit holders and will in some cases reduce the regulatory compliance requirement and expand their useability. However, if you have any concerns about these changes and your ability to comply with the conditions of your standard rules permit, please email: combustion@environment-agency.gov.uk.

Bespoke Permits for Existing Standalone MCP 5-50MWth

If you cannot meet the conditions in a standard rules permit, you must apply for a bespoke permit. There are 2 types:

  • Simple bespoke (low risk) – does not require detailed air dispersion modelling
  • Complex bespoke (high risk) – does require detailed air dispersion modelling

The guidance sets out which type of bespoke permit you must apply for and the information you will need to provide.

Application forms to apply for a new bespoke permit can be found here.

Variations to Bespoke Permits

Application forms to vary a bespoke permit can be found here.

Aggregation

We would like to draw your attention to the guidance on aggregation. In summary:

  • You only need to aggregate NEW MCP where they share a common stack.
  • You should not aggregate existing MCPs even if they share a common stack.

Back-up Generators

Back-up generators (operated for less than 50 hours per year for testing) which are also Medium Combustion Plant DO require permitting at the relevant date.

Tranche A Specified Generators Greater than 5MWth

An Environmental Permit was required by 1st January 2025 for Tranche A Specified Generators with individual or aggregated capacity greater than >5MWth thermal input with emissions which have an emission of NO2 <less than 500mg/m3 NOX2 (@ 15% Oxygen) or are operated for less than 50 hours per year.

The Standard ELV of 190mg/m3 NOX2 will need to be met by 1st January 2025 for all Tranche A generators of this capacity operated for more than 50 hours per year, unless they do so to meet a capacity market agreement from the 2014 and 2015 Capacity Market Auctions that remain in force.

EA Review of MCPs Which Are Listed as Part of an Industrial Emissions Directive (IED) Installations Permit

For existing MCP between 5-50MWth which are listed as part of an Industrial Emissions Directive (IED) Installation permit the EA has now completed a review of these permits and in some cases have carried out EA led variations to add in the requirements for monitoring and emission limit values (ELVs) to meet the requirements of the medium combustion plant directive as a minimum.

If your IED permitted facility has directly associated activities or primary activities made up of existing 5-50MWth or new 1-50MWth MCPs which are not currently permitted, you should apply to vary your permit as soon as possible to remain compliant with the regulations.

We are now carrying out compliance checks to ensure that operators are monitoring and meeting these ELVs.

We are also preparing for a review of permits with existing 1-5MWth MCPs before the 1st January 2030. As part of these preparations, we will be contacting operators in the intensive farming sector to gather information about in scope existing 1-5MWth MCP at their chapter II IED facilities.

Further Information for Standard Rules Permit Holders

For correspondence to regarding compliance, monitoring returns and billing of standard rules permits you should use the mailbox MCPReturns@environment-agency.gov.uk.

You should use the AR1 form provided by email when your permit was issued to submit the monitoring returns. If you need a copy, you can request it using the above mailbox.

Providing Correct Contact Details

It is important you ensure we hold up to date contact details of the people in your organisation responsible for compliance with your Standard Rules Permit in order that we can continue to undertake compliance activities in an effective and efficient manner.

Your Environmental Management System, required by Condition 1.1.1 of your Standard Rules Permit is an appropriate place for you manage change in personnel responsible for compliance and corresponding with the regulator.

Please provide any updates to contact details using MCPReturns@environment-agency.gov.uk.

Guidance Updates

There are lots of guidance pages available on our website which give a more detailed understanding of the regulations when you need a permit and how to apply and comply. We have recently updated a few of these pages as follows:

Medium Combustion Plant Screening Tool Guidance

https://www.gov.uk/guidance/medium-combustion-plant-screening-tool

The guidance for using the SCAIL screening tool has been updated to provide instructions to applicants for how to screen back-up generators. Key updates include instructions that:

  • Applicants are instructed to set operating hours to match their testing regime, to a maximum of 50 hours per year.
  • Emergency use hours related to power outages do not need to be included in the assessment.
  • Applicants must now provide information about their testing schedule, including typical and maximum test durations.
  • Applications should also include evidence relating to the likelihood of power outages, such as:
    • historical data of frequency and duration of outages
    • any planned infrastructure upgrades or maintenance that may influence reliability

Specified Generator – Apply for an Environmental Permit

https://www.gov.uk/guidance/specified-generator-apply-for-an-environmental-permit

The air emissions risk assessment guidance for Specified Generators has been updated to allow applicants to use the SCAIL screening tool in cases where the Specified Generator Screening Tool cannot be used. The updated guidance sets out:

  • When SCAIL can be used as an alternative screening method to the Specified Generator Screening Tool, for example, when fuel types are unsupported or horizontal stacks are present.
  • How applicants should add Human Health receptors within SCAIL.
  • How to interpret SCAIL results when assessing emissions from this plant.

Guidance for Setting Emission Limit Values for New Fuels

The EA have been directed by the secretary of state to set ELVs for new fuels. On the 14th October 2024 the Environment Agency published guidance which explains how to meet emission limit values for hydrogen combustion plants over 1MWth. It set ELVs for oxides of nitrogen (NOx) and Carbon Monoxide (CO) aiming to ensure no increase in NOx or CO emissions compared to the combustion of natural gas.

Hydrogen fuel including blending with natural gas is now permitted on certain standard rules MCP and SG permits. You can also apply to use Hydrogen as a fuel on a bespoke MCP and/or SG permit.

Regulator Position Statement (RPS) 337 on Alternative Fuel Use in MCP and SG

Published 4 July 2025

This RPS was published on 4 July 2025. It allows substitutes to gas oil such as HVO (Hydrotreated vegetable oil) to be used without requiring a permit variation. Permits issued since 1 October 2024 will have a condition which will allow substitute fuels to be used ‘as agreed in writing with the EA’, this RPS covers the gap for older permits until they are revised through operator led variations or an EA led permit review, at which point the RPS will be withdrawn. We know that there are likely to be more alternative fuels coming forward in the future e.g. Industrial Heating Oils, this RPS may be updated in future to add more substitute fuels.

To support this RPS we have amended our application forms so that you can now select gas oil substitute fuels. We have also updated our guidance as mentioned above. Gas oil substitutes are now also included as a fuel in some of our standard rules permits. You can also apply to use Gas oil substitutes as a fuel on a bespoke MCP and/or SG permit.

Regulatory Position Statement (RPS) 353 Monitoring of Back-up Generators

Published 9 July 2025

This RPS was published on 9 July 2025. It allows operators to seek agreement for no or reduced monitoring of back-up generators (i.e. limited hours MCP) where no safe or permanent means of sampling is available. This has been put in place to reduce the regulatory burden on operators where there is no ELV to be met and no means to monitor emissions safely.

Regulatory Position Statement (RPS) 354 on Mobile Boilers

Published 7 July 2025

This RPS was published on the 7 July 2025. It removes the requirement for an environmental permit where temporary steam and hot water boilers are hired as replacement for stationary boilers (i.e. there is no increase in operational installed capacity) whilst we develop a more proportionate permitting approach for mobile boilers. This RPS includes use of mobile boilers at permitted regulated facilities.

Subsistence Charges for MCP and SG Permit Holders

From November 2024 to January 2025, we held a consultation on changes to subsistence charges for bespoke MCP and SG permits. The consultation response is now available and new charges came into force from 1 July 2025.

Medium combustion plant (MCP) annual subsistence costs for bespoke permits have previously been made using time and materials charges. From the 1 July 2025 we now use fixed rate annual subsistence charge for bespoke MCP and SG permits, instead of Time and Materials charges. We have also decided to standardise the charges paid across standard rules and bespoke MCP and SG permits depending on how many combustion plant are operated. Here are the links to the consultation response and amended charges scheme.

In addition to the above from April 2025 to May 2025 we held a further consultation on subsistence charges which also impacts MCP and SG permit holders. The purpose of this consultation was to review the charges scheme to reflect the rising costs of delivering our services and modernising to digital services. The consultation response was published on the 1 August 2025 and the “Changes to Environment Agency charging” section of our Environment Agency fees and charges – GOV.UK page has now been updated to include information about the inflationary uplift which will be applied annually on 1 April.

We acknowledge that we are yet to bill for 25/26 financial year, but we are working hard to make changes to our systems to allow for this soon.

If you hold a permit and you think your billing contact details are incorrect or have changed, please email combustion@environment-agency.gov.uk or let your local Environment Officer know so they can update our systems. Include your EPR number and operator name in the communication.

Decarbonisation Readiness (DR) New Requirement

On 15 October 2024, the Department for Energy Security and Net Zero (DESNZ) published their Consultation Response on Decarbonisation Readiness (DR) for Power. This responds to the consultees comments and sets out the government position on how DR will be implemented.

The Statutory Instrument to make this addition to the Environmental Permitting Regulations was laid on 31 October 2024.

The Environment Agency has been assigned a new duty focused on Decarbonisation Readiness for power generation. Effective from 28 February 2026, this mandate requires operators applying for an Environmental Permitting Regulations (EPR) permit for new or substantially refurbishing power generation facilities (including MCP and SG) to demonstrate how they can transition towards low-carbon technologies – either carbon capture or conversion to hydrogen – through a Decarbonisation readiness plan.

The Environment Agency held a consultation on guidance to support this new duty between March and May 2025 and on the 03 November published their consultation response and final guidance.

We have since consulted on charges for DR, the consultation response has also now been published. The charges can now be found in the charging scheme.

We have also consulted on new permit conditions for DR on affected standard rules permits. The consultation response was published on 23 February 2026 and the revised standard rule sets 2018 no 1 & 4 were published on 26 February 2026.

New application forms and updates to our online application service for new MCP and SG bespoke and SR’s with questions added for DR have also been published. MCP and SG guidance pages have also been adjusted to include information about DR requirements.

Existing MCP 1-5MWth

Over the next year we will be preparing to open for applications to permit existing MCP 1-5MWth. As part of this we will be looking at expanding our offering of standard permit rules via a consultation and considering ways we will stagger applications into the EA’s permitting service before the 1 Jan 2029 deadline. We do not yet have a date when we will be ready to receive these applications; we will communicate this to you via these briefing notes.

Pre-application Advice

Did you know we offer a pre-application advice service? You can use the service to make sure your permit application is correct. To access the service for MCP and SG applications use the ‘installations activities’ link towards the bottom of the page.

If You Have Any Other Questions

Please read the guidance here.

If you have any questions about specific permit applications, you can access pre-application support here, selecting the ‘installations activities’ form.

All other enquiries can be made to enquiries@environment-agency.gov.uk or call us on 03708 506 506.

Contact the Environment Agency

General enquiries: enquiries@environment-agency.gov.uk  |  03708 506 506

Permit & combustion queries: combustion@environment-agency.gov.uk

Monitoring returns & billing: MCPReturns@environment-agency.gov.uk

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