Part B activities: combustion and incineration permits
Source: gov.uk (2025-07-09)

Find out if Medium Combustion Plant Directive (MCPD) or specified generator regulations apply to your operations.

The MCPD aims to improve air quality by controlling emissions to air. It sets emission limits for these pollutants:
- nitrogen oxides – NOx
- sulphur dioxide – SO2
- dust
MCPD and specified generator regulations apply to some Part B activities, in particular for sections:
- 1.1 – combustion activities
- 5.1 – incineration of waste wood
When MCPD and specified generator regulations apply

To work out if the regulations apply to your combustion plant you must know:
- its rated thermal input
- its type
- the material it burns
- if it generates electricity
Some medium combustion plants (MCPs) and generators are excluded from the regulations. Read the guidance to check for exclusions:
- Medium combustion plants: when you need a permit (https://www.gov.uk/guidance/medium-combustion-plant-when-you-need-a-permit)
- Specified generators: when you need a permit (https://www.gov.uk/guidance/specified-generator-when-you-need-a-permit)
Follow these steps to find out if MCPD and specified generator regulations apply to your combustion plant and whether it’s also a Part B and therefore must have a part B permit.

Step 1: capacity

Combustion plant capacity is defined by its rated thermal input. It’s calculated using the net calorific value (CV) not the gross CV. You can ask the manufacturer for this value or you can calculate it using Association of Manufacturers of Power generating Systems (AMPS) method (https://www.amps.org.uk/downloads/) or the [Combustion Engineering Association’s Boiler Calculations](Boiler Calculations for MCPD – CEA (https://cea.org.uk/2023/11/29/boiler-calculations-for-mcpd/).

MCPD and specified generator regulations may apply to your combustion plant if it’s not excluded and the rated thermal input is:
- between 20MWth and 50MWth – go to step 2
- between 1MWth and 20MWth – go to step 3
- less than 1MWth if it generates electricity and is aggregated to a site specified generator
If it’s 50MWth or more MCPD and specified regulations do not apply. You must have an A1 installations permit (https://www.gov.uk/guidance/a1-installations-environmental-permits).

Step 2: type of plant

MCPD regulations apply and it’s also a Part B section 1.1 if you have one of these types of combustion plant:
- boiler
- furnace
- gas turbine
- compression ignition engine
Go to step 4 to see if specified generator regulations also apply.

If your plant is not one of these types and is between 20MWth and 50MWth you must read the guidance Medium combustion plant: when you need a permit (https://www.gov.uk/guidance/medium-combustion-plant-when-you-need-a-permit). MCPD regulations may apply to your plant, but you will not need a Part B permit.

Step 3: plant burns waste biomass

Waste biomass is defined in industrial emissions directive (IED) Article 31(3)(b).

If your plant burns waste biomass and its capacity is less than 3 tonnes per hour:
- MCPD regulations apply
- your plant is a Part B section 5.1
- waste must be visibly clean and untreated with chemicals
If your plant does not burn waste biomass that is not waste and is between 1MWth and 20MWth:
- you must read the guidance Medium combustion plant: when you need a permit (https://www.gov.uk/guidance/medium-combustion-plant-when-you-need-a-permit)
- MCPD regulations may apply to your plant
- you will do not need a Part B permit
If you burn waste wood that is contaminated, the plant is a small waste incineration plant and must comply with Chapter 4 of the IED (https://www.gov.uk/government/publications/environmental-permitting-guidance-the-waste-incineration-directive/environmental-permitting-guidance-waste-incineration).

You do not need a waste operation permit to store waste wood where you can meet the conditions of the regulatory position statement (RPS) Storing and drying waste wood for burning in a Part B Co-incinerator: RPS 213 (https://www.gov.uk/government/publications/storing-and-drying-waste-wood-before-burning-in-a-part-b-co-incinerator-rps-213).

You can treat small quantities of waste wood for combustion under a waste exemption T6: treating waste wood and plant matter (https://www.gov.uk/guidance/waste-exemption-t6-treating-waste-wood-and-waste-plant-matter-by-chipping-shredding-cutting-or-pulverising).

MCP of 1MWth equates to around 200 to 250 kilograms per hour depending on the calorific value of the waste. Plants under 1MWth do not need a MCPD permit.

MCP of 1MWth equates to around 200 to 250 kilograms per hour depending on the calorific value of the waste. Plants under 1MWth do not need a MCPD permit.

Go to step 4 to see if specified generator regulations also apply.

If your plant’s capacity is 3 tonnes per hour or more (equivalent to around 15 to 18MWth depending on the calorific value of the waste) it’s a Part A1 activity. Read the guidance for Part A1 installations (https://www.gov.uk/guidance/a1-installations-environmental-permits).

If you already have an environmental permit you may need to vary it to include MCPD requirements. You must do this from the date your combustion plant qualifies. If you’re applying for a new Part A1 installation permit the regulators will include MCPD requirements in your permit conditions. As part of your application you must submit information showing you can meet the required emission limit values (ELVs).

Step 4: plant generates electricity

If your plant also generates electricity, it’s a Part B and both MCPD and specified generator regulations apply.

If it does not generate electricity, your plant is a Part B and MCPD regulations apply.

Dates for meeting MCPD and specified generator requirements

You must check the date from which you must meet MCPD and specified generator requirements.

New MCP

If your MCP was put into operation from 20 December 2018, it’s classed as ‘new’. You must apply for and have a permit granted from the date you commission your MCP.

Existing MCP

If your MCP was put into operation before 20 December 2018, it’s classed as ‘existing’.

You do not need to make a permit application. Your local authority permit will automatically transfer to the Environment Agency.
- for MCP with a capacity of 5MWth or less than 50MWth the transfer will have happened on 1 January 2024
- for MCP with a capacity of 1 MWth to less than 5MWth the transfer will take place on 1 January 2029
The Environment Agency may amend your permit once it is has transferred if it is found to be non-compliant with the MCPD.

Tranche A or B specified generator

Your generator is classed as Tranche A and means you have more time to meet the requirements, if one of these apply:
- it was put into operation before 1 December 2016
- any capacity agreement or balancing services or Feed-in Tariff contract ended before 1 October 2017
All other generators are classed as Tranche B. They’re usually new builds or operating under an agreement or contract after 1 October 2017. They must meet the requirements by 1 January 2019.

Check the latest deadlines for Tranche B generators in NRW’s Regulatory Decision (https://naturalresources.wales/about-us/what-we-do/what-we-regulate/regulatory-decision-operating-a-schedule-25b-tranche-b-specified-generator-for-research-and-development/) for sites in Wales.

For the detail see the guidance Specified generators: when you need a permit (https://www.gov.uk/guidance/specified-generator-when-you-need-a-permit).

When both MCP and specified generator regulations apply

You must:
- meet the requirements with the stricter emission limits
- get your permit by the earliest date set in the regulations
More than one activity

If the MCP is a directly associated activity to a different Part B or A(2) installation outside of sections 1.1 and 5.1 you’ll need 2 permits:
- a Local Air Pollution Prevention and Control permit for the primary activity from the local authority
- a MCPD standalone environmental permit to meet MCPD requirements from the Environment Agency or Natural Resources Wales (NRW)
The MCPD regulators will consult the relevant local authority on the MCPD permit conditions.

When a BAT assessment is required

A best available technique (BAT) assessment is required for MCPs that are:
- on a Part A1 and A2 regulated installation and one or more MCP is part of the whole installation
- part of a Part B installation – BAT applies to the whole installation, but for air emissions only
MCPD ELVs are set as a minimum standard on all other MCPs unless they’re exempt from meeting ELVs. See the guidance Complying with MCPD emission limit values (https://www.gov.uk/guidance/medium-combustion-plant-mcp-comply-with-emission-limit-values).

The regulator will do the BAT assessment.

Apply for a Section 5.1 or 1.1 Part B permit

Before you apply for your permit you must read the statutory guidance. You can request the following by making a basic request using the pre-application advice service (https://www.gov.uk/guidance/get-advice-before-you-apply-for-an-environmental-permit).
- process guidance note (PGN) 1/1 (21) – combustion plant of capacity 20MWth to 50MWth
- PGN 5/1 (21) – incineration or combustion of waste wood
You can use these PGNs for:
- a description of BAT for these activities, including mandatory requirements
- a list of techniques that can be used
- what may be included as permit conditions
You must apply for a bespoke MCPD or specified generator environmental permit. See guidance on how to apply for a:
- MCPD environmental permit (https://www.gov.uk/guidance/medium-combustion-plant-apply-for-an-environmental-permit)
- specified generator environmental permit (https://www.gov.uk/guidance/specified-generator-apply-for-an-environmental-permit)
Complete form part C2.5 (https://www.gov.uk/government/publications/application-for-an-environmental-permit-part-c25-vary-to-add-a-new-mcpsg-or-change-an-existing-mcp-or-sg-permit) for a new MCP that was previously a section 1.1 or 5.1 Part B activity.

Regulators

In England, Wales and Northern Ireland, Part B activities are currently regulated by local authorities. Where an activity is both Part B and MCP or specified generator, from the date your combustion plant qualifies, they are regulated by:
- Environment Agency for England
- NRW for Wales
- Department of Agriculture, Environment and Rural Affairs (DAERA) for Northern Ireland
The Scottish Environment Protection Agency (SEPA) is the regulator for all of these activities in Scotland.

Contact your regulator

England

Contact the Environment Agency

General enquiries

National Customer Contact Centre PO Box 544RotherhamS60 1BY

Email xxx@xxx.xx (mailto:xxx@xxx.xx)

Telephone 03708 506 506

Telephone from outside the UK (Monday to Friday, 8am to 6pm GMT) xx-xxxx-xxxx

Monday to Friday, 8am to 6pm.

Wales

Contact NRW (https://naturalresourceswales.gov.uk/permits-and-permissions/medium-combustion-plant-and-specified-generator-activities/?lang=en).

Northern Ireland

Contact DAERA (https://www.daera-ni.gov.uk/articles/medium-combustion-plant-directive-and-specified-generators)

Scotland

Contact SEPA (https://www.sepa.org.uk/regulations/pollution-prevention-and-control/medium-combustion-plant/)