Acid emission controls ‘fail to protect habitats’

Conservation agencies in England and Wales say tighter controls on acid emissions from power stations set by the Environment Agency are not enough to protect habitats. Meanwhile, three power stations run by Npower and Scottish and Southern Energy have failed to meet the deadline to fit sulphur abatement.

Natural England and the Countryside Council for Wales (CCW) say tighter controls on emissions of sulphur and nitrogen oxides, which came into force on 1 January under the large combustion plant Directive (LCPD), fail to protect sensitive habitats.

Under the LCPD, 13 coal- and oil-fired power stations have opted either to meet tighter emission limits on the acid gases SOx and NOx, or enter a UK acid gas emissions trading scheme. Most have had to install expensive flue gas desulphurisation and overfire air abatement equipment to achieve the cuts.

Nine other stations have opted out of meeting these requirements and can only operate for limited hours before closing by the end of 2015 (ENDS Report 374, p 38 ).

The power sector also recently fell under the pollution prevention and control regime. This requires companies to use the ‘best available techniques’ to reduce emissions, potentially forcing them to go beyond the LCPD’s requirements.

Sites under PPC are required by the habitats Directive to assess the potential impact of their emissions on protected areas to ensure they have "no adverse effect".

But in its assessment of power station emissions, focusing on sulphur deposition, the Agency concluded they will have no adverse effect. The chief justification for this decision was the uncertainties involved in modelling critical load exceedances for habitats and the difficulty of attributing these to the power sector.

The Agency has sought to back up its decision by including a generic improvement condition in the PPC permits of all opted-in power stations, setting a total annual limit on SO2 of 70,000 tonnes by 2020. It says this is an 89% reduction from 2003 emissions, with most of the cut coming in the next few months.

Operators must also monitor habitat acidification to track changes. The Agency says if this proves its decision was wrong, power stations will have to make further cuts.

Nevertheless, the conservation agencies do not support the Agency’s decision. They argue that, despite emission reductions by 2020, almost 40% of the UK’s sensitive ecosystems will still exceed critical loads for sulphur and nitrogen.

Simon Bareham, senior adviser at the CCW, said uncertainty over the impact of power stations’ emissions on habitats does not mean there are no adverse effects.

The Agency says nitrogen deposition from agriculture contributes more to exceedances than power stations.

The CCW is also concerned about weaker NOx limits at Npower’s Aberthaw station in South Wales. It is permitted to release 1,200 milligrams of NOx per cubic metre compared with 500mg/m3 at other coal-fired plants.

The Agency says the site’s boiler design means it is not possible to fit overfire air, which other power stations use to control NOx. It is requiring Npower to assess alternative ways of cutting NOx.

The Agency has also revealed that three power stations have failed to meet the 1 January deadline to fit flue gas desulphurisation. Scottish and Southern Energy’s Fiddlers Ferry and Ferrybridge stations and Aberthaw have fallen back on an LCPD derogation which allows them to operate at a reduced capacity - with a significant loss of income - until FGD is installed.

The sites were caught out by the failure of a long-running Environment Department (DEFRA) campaign to limit the impact of the LCPD, which meant some companies were uncertain how it would affect them (ENDS Report 372, p 37 ).

Scottish Power has also yet to fit FGD at its Longannet site. It has opted to comply with the LCPD through the national emissions reduction plan, which is an acid gas trading scheme (ENDS Report 386, p 49 ). This will require the firm to buy allowances to cover the site’s higher emissions.

Some power companies have proposed a new generation of so-called clean coal power stations to replace ones closed as a result of the LCPD (see pp 26-29 ).

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