What to do before you apply for a standalone Medium Combustion Plant (MCP) permit between 1 and less than 20 MW thermal input

If your Medium Combustion Plant (MCP) is also a Specified Generator (SG) or Part B activity, you can find information on preparing your application here.

You must provide the following information with your permit application:

  • Air quality modelling assessment screening
  • Whether or not your MCP is located within Air Quality Management Area (AQMA)
  • Non-technical summary
  • Confirmation that you have a written management system in place
  • Evidence to show your ability as a permit holder (the operator)

Air quality modelling assessment screening

You will need to determine whether the air emissions from your MCP are a risk to any protected habitat sites close to your MCP. These include Ramsar sites, Sites of Special Scientific Interest (SSSI), Special Areas of Conservation (SAC), Special Protection Areas (SPA) and Marine Conservation Zones.

You can use our map of environmental data to search for protected habitat sites by selecting protected areas from the layer list.

Use our protected areas search map

You will need to use the screening distances in the table below to identify any protected habitat sites close to your MCP. The screening distances will depend on the size and fuel type of your MCP.

Minimum screening distances to the habitat sites 

Fuel type used

Rated thermal input (MWth) of any MCP

Minimum distance from MCP to a Site of Special Scientific Interest (SSSI) or marine conservation zone (metres)

Minimum distance from MCP to a Special Conservation Area (SAC), Special Protection Area (SPA) or Ramsar wetland (metres)

Natural gas, gas oil and woody solid biomass

1 to 2

750

750

Natural gas, gas oil and woody solid biomass

2 to 5

1,000

1,000

Natural gas, gas oil and woody solid biomass

5 to 10

1,500

1,500

Natural gas, gas oil and woody solid biomass

10 to 20

2,000

2,500

Natural gas, gas oil and woody solid biomass

20 to 50

2,000

5,000

Gas other than natural gas

1 to 2

1,000

1,000

Gas other than natural gas

2 to 5

1,500

1,500

Gas other than natural gas

5 to 10

2,000

4,000

Gas other than natural gas

10 to 20

2,000

5,000

Gas other than natural gas

20 to 50

2,000

10,000

Solid and liquid heavy fuel oil

1 to 2

2,000

2,000

Solid and liquid heavy fuel oil

2 to 5

2,000

4,000

Solid and liquid heavy fuel oil

5 to 10

2,000

8,000

Solid and liquid heavy fuel oil

10 to 50

2,000

10,000

MCPs operating outside the minimum screening distances

If your MCP is operating outside the minimum screening distances given in the table above, your MCP has ‘screened out’ and therefore you do not need to carry out any air quality modelling assessments to support your application.

If your MCP has ‘screened out’ but is a specified generator, individually greater than 20 MW thermal input in size or burns 50 kg or more per hour of waste biomass, please read: What to do before you apply for a standalone Medium Combustion Plant (MCP) less than 50MW thermal input that is also a Specified Generator (SG) or Part B activity.

MCPs operating within the minimum screening distances

If your MCP is operating within the minimum screening distances to the protected habitat sites given in the table above, you will need to use the SCAIL Combustion screening tool to determine whether the air emissions from your MCP are a risk to the protected habitat sites you have identified and whether you need to do a more detailed assessment of them. You will need to input the relevant screening distances from the table above into the SCAIL Combustion screening tool.

To use the SCAIL Combustion screening tool, you need specialist knowledge of air quality assessment and dispersion modelling so you may need to use a consultant to complete this for you. This may take a few weeks to complete, so you will need to complete that before making your application.

You can find a consultant in ENDS Directory. They’ll charge for their services.

If your MCP can meet 'new' MCP Emission Limit Values (ELV) set out in the relevant table of Annex II of the Medium Combustion Plant Directive (MCPD), you can input these values into the SCAIL combustion screening tool to demonstrate a low risk impact to the environment.

If you voluntarily declare that your MCP can meet the 'new' MCP Emission Limit Values (ELV) we will include those limits in your permit which you will need to comply with from 1 January 2025.

You can voluntarily declare that your MCP can meet these limits in your application form.

If you do not declare that your MCP can meet the ‘new’ MCP Emission Limit Values (ELV), we will include ‘existing’ plant limits (relevant to your MCP) in your permit which you will need to comply with from 1 January 2025.

The SCAIL combustion screening tool

The SCAIL combustion screening tool is available on the Centre for Ecology and Hydrology (CEH) website which is used by all UK Regulators for the assessment of boiler, engines, generators and turbines.

Visit the SCAIL tool on Centre for Ecology and Hydrology (CEH) website

There is a general SCAIL Combustion user guide available on the CEH website to help you complete the tool.

We have our own SCAIL Combustion screening tool user guide that explains how to use the tool, how to assess the results and how to present the results with your permit application.

The SCAIL combustion screening tool will either 'screen out' or 'screen in' your MCP.

If your MCP 'screens out' using the SCAIL combustion screening tool, you do not need to carry out any air quality modelling assessments, but you will need to complete the SCAIL results template and submit that with your permit application.

If your MCP 'screens in' using the SCAIL combustion screening tool, you will need to carry out a site-specific air quality modelling assessment that assesses the risks to the protected habitats and submit that with your permit application.

Air quality modelling assessments requires specialist knowledge so you will need to use an environmental consultant to do this for you. This may take a few weeks to complete, so you may wish to do that before making your application.

You can find a consultant in ENDS Directory. They will charge for their services.

Please contact Natural Resources Wales if you want to do your own detailed modelling.

MCPs located within an Air Quality Management Area (AQMA)

If your MCP is located within an Air Quality Management Area (AQMA) you must provide:

  • Details of the AQMA
  • Actuals emissions from your MCP

Find out if you are in an Air Quality Management Area on the DEFRA website

We will consult the Local Authority to check if your MCP is identified in the associated Air Quality Management Plan and if it is, your MCP emissions may be identified as adversely impacting air quality in the area.

The local authority, in its plan, will identify how much stricter the Emission Limit Values (ELVs) needs to be to deliver a noticeable improvement to air quality. We will include the agreed stricter ELVs in your permit conditions.

Non-technical summary

You will need to provide a summary that explains your application, in non-technical language as much as possible, avoiding technical terms, detailed data and scientific discussion. This should include a summary of the site and a summary of the key technical standards and control measures arising from your risk assessment

If your application is for a mobile plant you must tell us how the activities you want to carry out could impact land quality, describe the mobility of your plant and how you intend to operate.

Confirmation that you have a written management system in place

You must have an effective, written management system in place that identifies and reduces the risk of pollution. You may show this by using a certified scheme or your own system. Your permit requires you (as the 'operator') to ensure that you manage and operate your activities in accordance with a written management system.

You can find guidance on management systems on the GOV.UK web-page ‘Develop a management system: environmental permits’.

You will be asked to confirm you have read the guidance and your management system meets our requirements in the application form.

Evidence to show your ability as a permit holder (the operator)

When determining your application we must consider whether you will be a competent permit holder ('operator'). We will look at your technical ability and whether you have been convicted of a relevant offence. A relevant offence is one relating to the environment or environmental regulation.

We will also check to see if you have been declared bankrupt or insolvent and can check your financial standing by way of a credit check. We will also check that you have a management system in place.

Related document downloads

SCAIL Results Template EXCEL [103.2 KB]
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