Emission controls for medium combustion plants

Natural emission control. Photo: © philipus - Fotolia.com

EU-wide application of the most stringent standards now used in member states would reduce NOx emissions from these plants by nearly 80 per cent by 2025, but the new directive will deliver less than half of this reduction.

As part of its air quality package from December 2013, the Commission has proposed a new directive to limit air pollutant emissions from combustion installations with a thermal input between 1 and 50 megawatts (MW).

Emissions from large combustions plants (>50 MW) are covered by the industrial emissions directive (IED), and there are currently discussions about setting emission standards for the smallest combustion installations (<1MW) in the Ecodesign Directive.

The current proposal covers nearly 143,000 medium-sized combustion plants (MCPs) now in operation in the EU, which in 2010 together emitted some 554 thousand tons (kt) of nitrogen oxides (NOx), 301 kt of sulphur dioxide (SO2) and 53 kt of particulate matter (PM).

Even without additional measures, by 2025 these emissions are expected to come down somewhat (by respectively 18, 42 and 9 per cent), primarily as a result of changes over time in the fuel mix and activity levels. But the potential to further reduce these emissions is significant.

Many member states already regulate emissions from MCPs through permit systems or emission limit values. The impact assessment shows that EU-wide application of the most stringent emission legislation now used in member states (for the different fuel types and size classes) would reduce emissions of NOx, SO2 and PM by 79, 88 and 94 per cent, from 2010 to 2025.

The Commission’s proposal introduces binding emission limit values that are differentiated according to plant capacity, age and type of installation, with the strictest standards for new plants bigger than 5 MW. The limits would apply to all new plants as from two and a half years from the date of adoption, which may take place in 2015. Existing installations would be given a long transition period, up to 2025 for the larger (5–50 MW) plants and up to 2030 for the smaller ones.

In its proposal, the Commission has chosen less strict emission limit values compared to those already in place in some member states, especially regarding NOx control. The proposed emission standards can be achieved solely by using cheaper primary emission abatement measures – more expensive exhaust gas after-treatment systems will generally not be required. Overall, the Commission’s proposal is expected to achieve similar reductions for SO2 and PM as those indicated above, but the NOx emissions would only be reduced by about 37 per cent.

In order to further reduce the cost of implementing the proposed directive, operators will not require permits, as is the case for large combustion plants. Instead they need only notify the competent authorities, which in turn will ensure registration. The monitoring and reporting obligations have also been set at a minimal level, only requiring periodic measurements once every three years for the smaller (up to 20 MW) plants and annually for the bigger plants.

Moreover, member states can exempt plants that do not operate for more than 500 hours per year from compliance with the emission limit values.

Member states are however expected to apply more stringent emission limit values (called benchmark values) to individual plants in zones that do not comply with the EU’s air quality standards. These benchmark values are said to reflect the best available techniques (BAT) and are set out in a separate annex.

Christer Ågren

The proposed new directive and the impact assessment

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