Emissions to air
The principal emissions from burning coal are carbon dioxide (CO2), sulphur dioxide (SO2), oxides of nitrogen (NOX), hydrogen chloride (HCl), and particulates (dust). Our generating units have all been retrofitted with Flue Gas Desulphurisation (FGD) equipment which removes at least 90% of SO2 and HCl emissions before the flue gas is released via the chimney into the atmosphere.
We maintain investment in our emissions abatement equipment and consider this to be a high priority. Our FGD plant already complies with known future SO2 emissions limits to 2016. In 2008 we completed a programme to retrofit all units with low NOX technology – Boosted Over Fire Air systems – in order to ensure compliance with the NOX requirements of the Large Combustion Plant Directive (LCPD) which were strengthened in 2008.
Discharges to water
Procedures are in place to ensure that all discharges and drainage to water are monitored and treated where necessary to meet our discharge consent limits. There are a number of sources of discharge and drainage as part of the electricity generation process, including the cooling water used to cool the condensers, which as part of the steam cycle condense steam to water after it leaves the turbines and before returning to the boilers. Cooling water is abstracted mainly from the River Ouse and boiler feedwater originates from two boreholes on site. Approximately half of the water is returned to the River Ouse at a few degrees warmer than the river water.
The FGD process produces effluent water which is treated in a specially designed plant before it is discharged to the river, and there is also drainage from the main plant, coal plant and roads.
Disposals to land
When coal is burnt, ash is left as a residue. The finer particles of ash, pulverised fuel ash (PFA,) are collected from the flue gas by electrostatic precipitators; the heavier ash, furnace bottom ash (FBA) falls to the bottom of the boiler. The majority of ash is sold to the construction industry with the remainder sent for landfill at the power station’s adjacent Barlow Mound ash disposal site, which over time has been developed into farmland, woodland and wetland features providing a haven to many species of wildlife and birdlife.
We pay landfill tax on the PFA disposed of to the Barlow Mound. Through the Landfill Tax Credit Scheme, we are able to claim a tax credit against our donations to recognised Environmental Bodies. We have worked with Groundwork Selby since 2001 on projects designed to help mitigate the effects of landfill upon our local community.