Nearly final combustion plant BREF raises standards

Gasification, plasma gasification and multi-fuel combustion added to the final draft LCP BREF

The Drax power station
The Drax power station

The final draft of new European Union statutory guidance for design, operation and emission controls at large combustion plants (LCPs) has been published by the EU IPPC Bureau.

The BREF, or best available techniques (BAT) reference document, includes new information on combustion and abatement technologies and has new chapters on gasification (including plasma gasification) and multi-fuel combustion.

Unlike the previous, 2006, version of the BREF it includes official "BAT conclusions". These will eventually be published in the EU official journal and have the power of statutory guidance.

The final BREF is expected to be published in 2017 or 2018. Where changes are required national regulators will then have four years to reissue permits to LCP operators.

LCPs have a thermal input of more than 50MW. They include the largest EfWs and biomass, as well as fossil power plants, plus power plants at a range of industrial sites.

The biggest change between the 2006 BREF and its replacement is a large cut in the BAT-associated emission level (BAT-AEL) for emissions of nitrogen oxides (NOx).

For coal-fired facilities, the previous version allowed for 90-200 milligrams of NOx per cubic metre at larger existing plants (and 50-200mgNOx/m3 at new ones). A maximum rate of 200mgNOx/m3 can be achieved by installing selective non-catalytic reduction (SNCR) equipment.

The new draft gives a BAT-AEL of 85-150mgNOx/m3 for existing coal plants. Meeting the new maximum is likely to require more expensive selective catalytic reduction (SCR) equipment.

For power plants that convert to biomass, the yearly average BAT-AEL in the new draft is 40-150mgNOx/m3 for existing plants over 300MWth. There is a higher maximum of 250mg/m3 where fuels have a particularly high salt content.

NOx limits for biomass plants in general have been tightened up, falling from 150-250mgNOx/m3 to 70-150mgNOx/m3 for new, smaller scale units.

Aside from NOx, a new addition is a BAT-AEL for mercury from coal or lignite. Achieving it may require a further upgrade to power stations, namely the injection of activated carbon into the flue gas prior to entering a bag filter system.

National regulators will still not be legally bound to follow the new guidance, but will in future have to publish specific reasoning if they wish to depart from it in any environmental permit.

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