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Draft Air Quality Plan to tackle NOx emissions from diesel generators

The UK Government published its draft Air Quality Plan earlier this month for tackling nitrogen dioxide (NOx) emissions. As part of the plan, released on 5th May 2017, the Department for Environment, Food and Rural Affairs (DEFRA) is consulting on new measures to tackle NOx emissions from medium combustion plants (MCPs) and diesel generators by the end of 2018.

Within the UK, there has been rapid growth in the use of low cost, small scale flexible generators to provide heat and power for large buildings (offices, hotels, hospitals, prisons) and industrial processes, as well as decentralised power generation during periods of peak demand. Whilst the Government recognises that there is a role for some rapid-responding, small-scale generation (such as gas), the recent growth of (mainly diesel) generators that emit high levels of NOx relative to other MCPs is seen to be contributing to the deterioration of local air quality.

The consultation seeks views on draft plans to implement the Medium Combustion Plant Directive (MCPD) and emission controls on generators in England and Wales in order to improve air quality.

The Medium Combustion Plant Directive (MCPD) seeks to reduce air pollution by introducing emission controls for combustion plants in the 1 to 50MWth range. The Directive requires all plant in scope to be registered or permitted, and sets limits on the levels of pollutants that these plants can emit according to their type, size, age, fuel type and annual operating hours from December 2018 and existing plants in 2025 and 2030. It also requires operators to test emissions from their plants to demonstrate compliance with emission limits.

Air dispersion modelling indicates that diesel generators without stack design measures, such as multi-flue tall stack designs, operating pattern restrictions or abatement to achieve stringent ELVs are likely to cause breaches of the short term NO2 air quality standard if there are sensitive receptors nearby. The NO2 short term standard is an hourly mean limit value of 200µg/m3, not to be exceeded more than 18 times a year.

The Environment Agency (EA) recommends that site specific assessments are conducted for all new permit applications unless large multi-flue stack configurations are proposed. From 1st January 2019 all generators will require a permit, with a few exceptions.

Wiser Environment can provide site specific assessments, including air dispersion modelling for air quality assessments, required in both planning and environmental permit applications, as well as for ongoing compliance and best practice. Combining in-house expertise and the world leading industrial air pollution modelling software, ADMS (Atmospheric Dispersion Modelling System) 5.2, we deliver accurate and timely air quality assessments.

If you think you will be affected by the new Directive and permit requirements, contact Graeme on 01480 462 232 for further information.