CQI East of Scotland
Proposed Kincardine Biomass Power Station -
Date: Tuesday 12 January 2010
Venue: Coulson Building, Heriot-Watt University, Edinburgh
Hosts:
Joint Meeting with the Institute of Environmental Management and Assessment, Alan Harper, Head of Environment Department
Speakers:
Lee Walker, Process Engineer, Scottish Power;
Duncan Hutchison, Civil Engineer, Abrach Engineering
Words - Brian Murray
PDF version of the presentation can be seen here - Proposed Kincardine Biomass Power Station
Duncan began by outlining the legislative background leading to the need for a Combined Heat and Power Station (CHP): EC Urban Waste Water Treatment Directive 1991 (UWWTD) means that sewage sludge can no longer be dumped at sea. This led to Scottish Power and Scottish Water being obliged to take out a PFI contract for the disposal of dried sewage sludge. In Glasgow, this is treated and turned into Waste Derived Fuel (WDF) at the Daldowie plant. Currently, this is trucked daily to Longannet Power Station where it is co-fired along with coal and biomass wood pellets.
This practice made Longannet eligible for a Renewals Obligation Certificate (RO). The RO is the main support scheme for renewable electricity projects in the UK. It places an obligation on UK suppliers of electricity to source an increasing proportion of their electricity from renewable sources.
A Renewables Obligation Certificate (ROC) is a green certificate issued to an accredited generator for eligible renewable electricity generated within the United Kingdom and supplied to customers within the United Kingdom by a licensed electricity supplier. One ROC is issued for each megawatt hour (MWh) of eligible renewable output generated
However, under the EC Waste Disposal Directive 2000 (WDF), Longannet must cease burning the WDF as soon as it is practicable, owing to problems with lowering the current emission levels. A number of sites for a CHP station were considered across Scotland. Longannet was finally chosen due to land already being in SP ownership, local support for WDF firing and ease of grid connection. A turnkey project was proposed with a capital cost of circa £90m. Civil Enabling Works were commenced on September 2008 to prepare the site at a cost of £3m.
Historically, during WW2, the whole site was a munitions dump with concrete bunkers, roads and a light railway. Longannet Power Station occupies the eastern half of the site with the CHP being on the western half. The CHP site has been cleared of bunkers etc and a platform has been constructed utilising pulverised fuel ash from the adjacent station along with associated drainage works and a site road. A new Pollution Prevention and Control (PPC) certificate has been obtained by Scottish Power to cover the new CHP.
Lee took over at this point to present the Project Systems associated with the new station. This will be a steam/water cycle modern plant which is as efficient as possible. It will have an output of 25.5 MWe (megawatt electrical) compared with 2,400MWe for Longannet: CHP is designed for a town such as Kincardine whereas Longannet is a strategic power asset. As already stated, the WDF is delivered daily from Glasgow to Longannet PS with the composition being monitored to maintain emission limits. This will be switched to the Kincardine CHP when it is ready. The waste wood to be used is under a subset of the Waste and Resources Action Programme (WRAP). Acceptable waste wood will include telegraph poles, sleepers, demolition timber, MDF, off-cuts, pallets and green forestry residues. They cannot accept waste wood if it has a halogen content greater than 1% by mass.
The waste wood is sorted by mechanical means using magnets and other devices. The wood is shredded, mixed with WDF and fed to the furnaces which have natural gas for start up and combustion support. The downstream Flue Gas Treatment (FGT) has electrostatic precipitators for clean ash capture, sodium bicarbonate addition to capture SOx and activated charcoal filters to capture heavy metals. Finally, additional bag filters are employed to capture FGT residues and meet dust emission limits according to the Waste Incineration Directives.
Lee concluded by stating that Continuous Emission Monitoring Systems (CEMS) are used to measure emissions from the stack. At all points, the systems have been designed to provide quality of function and purpose so that the CHP will enhance the quality of life for the surrounding area. A lively Q&A session followed.