Clearing the air

6th July 2018

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  • Energy ,
  • Biodiversity ,
  • Legislation


Grant Anderson

Change is afoot in the energy supply market, with the introduction of legislation to control combustion plant emissions. But how prepared are operators and regulators? John Dickson and Jane Hall investigate.

The EU has raised concerns in recent years over the use of medium-sized combustion plant (i.e. plant with a thermal input of 1-50 MW), particularly diesel engines, in the energy supply market and other applications. The polluting gases emitted by combustion plant – including oxides of nitrogen (NOx), particulates and sulphur dioxide (SO2) – have serious effects on air quality, which have led to calls for better control.

The EU and UK governments have recognised the impact that medium combustion plant can have on air quality, and brought in legislation to control emissions. But what is driving the regulation? What are the impacts on operators? And are regulators ready for this entry to the regulatory framework?

The UK’s Department for Environment, Food and Rural Affairs considers that “poor air quality is the largest environmental risk to public health in the UK” (see Defra’s impact assessment on amendments to environmental permitting regulations to improve air quality, December 2017). The combined impact of pollution from NO2 and particulates is estimated to lead to 50,000 premature deaths each year, at a cost of around £30bn. Air pollution also has detrimental effects on biodiversity and crop yields (see Defra’s impact assessment 2039, November 2016).

Medium-sized combustion plant is used for a variety of applications, including space heating, electricity generation, and provision of heat and steam for industrial processes. An EU report found that medium combustion plant is a significant source of air pollutants (see

The EU developed the Medium Combustion Plant Directive (MCPD) to bring this plant under legislative control, improve air quality, help achieve national emissions ceilings and address non-compliance with existing ambient air quality standards (see EU directive 2015/2193, 25 November 2015). The EU considered that controls on medium combustion plant could deliver 10%-20% of its required reductions in SO2, NOx and particulate emissions (see

In the UK, there has been growth in the use of small and medium-sized generators to provide capacity and balancing services for the energy supply market. The forecasted growth of high NOx-emitting generators was thought to have the potential to lead to breaches of air quality objectives in some areas. The increase in emissions, taken together, could affect the UK’s ability to achieve national emissions ceilings (see Defra’s impact assessment 2039, November 2016). For these reasons, the UK government introduced further controls on generators when it transposed the MCPD into UK legislation.

In England and Wales, the MCPD was transposed into UK legislation through a 2018 amendment to the environmental permitting regulations (England and Wales) 2016 (EPR), which inserted schedule 25A, concerning medium combustion plant, and schedule 25B, concerning additional generator controls. The directive was transposed through the pollution prevention and control (PPC) regulations in Scotland and Northern Ireland, with similar requirements. However, in Scotland, the additional generator controls were not included.

The detailed requirements of the directive and amended regulations are complex, and the regulators are due to produce application forms and guidance in the near future. The first deadlines for holding permits are in December 2018, so operators of medium combustion plant and generators should ensure they understand the implications of the regulations and plan compliance measures, if they have not done so already.

Operators should take steps to:

  • Develop an inventory of combustion plant and its operating characteristics, such as type, size and operating hours
  • Determine what applies to their operation, and when it applies
  • Determine when they need to apply for a permit, and secure the resources to do so
  • Check emissions from current plant, and identify whether upgrades are required
  • Develop systems to address the requirements for monitoring and reporting, and incorporate them into their energy management system.

Which type of plant does the regulation cover?

Medium combustion plant with thermal input between 1 and 50 MW and specific controls on generators (which can include generators below 1 MWth in some instances) are within the scope of the amended regulations. Operators will have to obtain a permit (or in some cases, register plant), which will control emissions and require monitoring, reporting and records to be kept.

What is energy balancing, and what role does medium combustion plant play?

The National Grid procures energy balancing services to ensure the security and quality of the electricity supply. It must be able to respond rapidly to changes in demand for electricity; this is achieved in part by using small, fast-start electricity generating plant. Diesel has traditionally been a favoured technology as it is reliable, and can start operating quickly and at a relatively low cost.

There is uncertainty about some detailed requirements, but it is hoped that these will be clarified when guidance is issued.

In terms of the impact on industry, the government has held consultations with interested parties in recent years on MCPD implementation. In response to its communications with consultees, it has made several developments, which have resulted in complex amendments to UK regulations. One theme in the consultation responses was a call for greater clarity (see Defra’s impact assessment on amendments to environmental permitting regulations to improve air quality, December 2017).

This uncertainty has had a negative impact on operators, with the overall costs of compliance increasing owing to the large number of combustion plant that is now captured by the regulations – and particularly due to the removal of a minimum threshold for some ‘specified generators’. The MCPD allows most older plant a transitional period, giving operators time to respond to the requirements. However, the England, Wales and Northern Ireland legislation has taken a more stringent approach and requires certain ‘specified generators’ to achieve compliance by January 2019. This leaves limited time to upgrade existing plant.

Furthermore, in England and Wales, it was anticipated that most facilities would be captured by a simplified ‘standard rules’ permitting approach. However, based on the draft screening criteria that regulators have produced, many operators are likely to need to secure a permit through the more complex regulatory approach, which may require them to produce an air quality assessment.

The changes will also impose a burden on the regulators. The MCPD and generator controls are expected to bring around 25,000 items of plant into regulation in England and Wales (see the Department for Business, Energy and Industrial Strategy’s impact assessment on the medium combustion plant directive transposition, 5 May 2017) and 1,200 in Northern Ireland (see This will place extra resource requirements on the regulators at a time when resourcing is under pressure.

Commenting on the regulations, environment minister Thérèse Coffey has said: “These regulations will help deliver further substantial reductions in emissions, while minimising the impact on energy security and costs to businesses.” However, the question remains: are regulators and operators resourced to implement and meet the regulations’ requirements within the tight deadlines?

The keys to success

How the regulators can ensure the directive is achieved

John Dickson CEnv, MIEMA and Jane Hall CEnv, MIEMA are associates at Atkins, both specialising in environmental permitting and regulatory compliance

Image credit: iStock


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