Deadline looms for new permit applications for some boilers, engines, generators and turbines

If you operate your own boiler, engine, generator (including back-up/stand by) or turbine for the production of heat, steam, power or electricity, you may be running a Medium Combustion Plant (MCP) and/or specified generator, and it is likely you will have to apply for a permit from us to continue using it due to new rules coming into place.

Here at Natural Resources Wales, we are here to help and support you to check if the new rules will affect you and to help you do what you need to to make sure you comply.

What are the new rules?

The new rules mean that certain boilers, engines, generators and turbines will require a permit to help control emissions of NOx, SO2 and dust and improve air quality.

These boilers, engines, generators, or turbines are known as Medium Combustion Plants or MCP.

An MCP is equipment used to burn materials (including waste) with a rated thermal input of between one and 50 megawatts, including:

  • a combustion unit, such as a boiler, engine, generator (including back-up/stand by) or turbine
  • any abatement
  • the attached stack or flue
  • air cooling, where it’s part of the combustion unit

Will I need to get a new permit for my MCP?

To check if you need a permit for your MCP, there are a few things you will need to know first:

  • The size of your medium combustion plant (expressed as megawatts thermal input). If you do not know the size of your medium combustion plant, you can use the MCP guidance on to help you calculate it
  • The date your medium combustion plant was first put into operation
  • The fuel used by your medium combustion plant
  • Whether your medium combustion plant is used for heat, steam, power and/or electricity

When you have all this information, you can use this tool to help you work out what permit you need: Do I need a medium combustion plant and/or specified generator permit? (

Are there any exceptions?

Yes, there are a number of MCPs that are excluded from the regulations including (but not limited to) certain mobile boilers, those that only use poultry manure as a fuel, those used for direct heating or drying of materials. A full list of exemptions can be found here.

When do I need to get my MCP permit?

If you have an MCP which first came into operation before 20 December 2018 (known as an existing MCP) between 5-50MW thermal input, you need to apply for a permit now to meet the 1 January 2024 permitting requirements.

If you want to start using a new MCP which is between 1MW and less than 50MW thermal input, you must apply for a new permit if you don’t have one already, or apply to change your current permit, so that you can meet the new rules.

How do I apply for a permit?

Go to our website: Natural Resources Wales / Find out if you need a permit for your boiler, engine or turbine and you will find lots of information about the MCP permits and details of how to apply for a permit.

How much will it cost?

The cost of a permit will depend on what type of MCP you have and what type of permit is required based on the risk to human health and the environment. Our permit costs can be found here.

I’m still confused about MCP permits and the new rules – how can Natural Resources Wales help me?

If you’re still not sure about whether you need a permit, or what you must do, please contact us for advice – we are happy to help:

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