Environment Agency (EA) – Medium Combustion Plant Directive (MCPD)

Application for permits for emergency back-up (standby) generating sets ‘in scope’ of the above (> 1000 kWth).

Following some recent discussions we considered it timely to remind AMPS Members, together with end users and plant operators on the requirements and process to obtain a permit for a generating set plant under what is known as the MCPD regulations.

MCPD applies to generating sets, boilers, and other combustion plant. This guidance is aimed at generating set applications, and is a BRIEF SUMMARY of the requirements.

As originally an EU Directive, it would not apply until the UK government ‘transposes’ the Directive into UK Law. This was done in England and Wales in 2016 then amended in December 2018 (The Environmental Permitting (England and Wales) (Amendment) Regulations 2018 – MCPD, Scotland and Northern Ireland followed. As we have devolved governments in the UK, then England and Wales has one set of legislation, Scotland and Northern Ireland having separate legislation. Links are given at the end for the devolved nations. This summary applies to plant located in England.

The regulations apply to plant on site with a thermal input above 1000 kWth. They apply to the site not the supplier or installer, and are retrospective. Eventually all plant ‘in scope’ will require a permit as a minimum.

The ‘Thermal Input’ is the energy in the fuel, so it could apply to sets rated above 300 kWm mechanical power (~ 375 kVA) for older, lower efficiency sets.

For example, if diesel engines were 40% efficient, then 1000 kW of input energy would result in 400 kWm of mechanical power.

Pth = P(r) * 100 / ηe


Pth   = thermal input power

P(r) = rated power (mechanical or electrical, which ever is available)

ηe   = effective efficiency (relevant for mechanical or electrical power)

MCPD controls apply to all ‘in scope’ MCP’s with a rated thermal input of each unit between 1 MWth and 50 MWth regardless of the type of fuel used.

To start the process see here.

If your generating set is not new, you may have difficulty determining the thermal input. AMPS have agreed a calculation sheet with the EA which can be found via the link on the above site or directly on the AMPS website here.

Follow the sheet progressively from the beginning.

Emergency backup (standby) generators

From 1 January 2019, a backup standby generator ONLY used to provide power at a site during an emergency is excluded from Emissions Limit Values (ELV). However, it is an MCP and requires a permit by the appropriate deadline.

Using a backup generator for the following is NOT classed as emergency use:

For an on-site emergency, there is no restriction on the total number of hours:

Number of hours you can test backup generators

You must not carry out more than 50 hours testing a year for each backup generator. You must get agreement in writing from your regulator if you want to increase this limit. The regulator can exclude commissioning time within the written agreement.

For each backup generator, you must record the number of hours you test during the year. This is to demonstrate that you meet the exclusion criteria.

If you exceed the limit of 50 hours testing a year without written agreement, the regulator will take appropriate enforcement action.

Definition of a Specified Generator:

The term ‘Specified Generator’ covers an individual generator or a number of generators if they are:

Permitting and compliance dates

For backup standby sets you must apply for your permit and have it in place by:

General notes

1.Industry lobbied at EU level, unsuccessfully, to get emergency plant completely removed from the MCPD. The Member States, and the now separate UK devolved nations do want to know where the plants are, how many there are etc. etc. 

So where the only combustion plant on a site is an emergency generator read the guidance here.

Then apply here.

For sites with multiple combustion plants follow the full guidance.

2.The EA requires the site to have an Environmental Management System.  For one thing, even with a standby generating set, there can be a significant quantity of fuel stored, not withstanding fresh and waste lubricating oil and glycol coolant. Stand-by generators are so common that they tend to be overlooked so something that forces consideration is understandable.

3.When you go through the application, the dropdown only offers the term ‘Gas Oil’ for what is commonly called ‘diesel fuel’ and there is no option for HVO. Gas oil is (currently) the correct designation for HVO and other diesel like fuels. Euromot did quite an extensive investigation into this for NRMM stage V:

Example from application site:

Local Authority or Environment Agency responsibility?

The MCP permitting system is operated by the EA. However if the site is within or near an Air Quality Management Area (AQMA), or a ‘habitats site’ follow the appropriate guidance as the Local Authority requirements may take precedence over MCP emissions limits.

A habitats site can be a:

If your MCP is of low risk to air quality and can meet the rules in a standard rule permit, the EA guidance sets the minimum requirements for the distance from the habitats site.

Also note that there may be other local planning restrictions on the site, noise for example.

Developed Nations links

Final reminder – it is the location of the plant which is important not the address of the operator or owner! Applications must be made to the applicable nation regulator via the appropriate link:




Northern Ireland

Any queries, please contact TechSec@AMPS.org.uk