By Russell Bishop, Economist at the CCC
Members of the CCC bioenergy review team went to Yorkshire to visit Drax power station. Drax is Western Europe’s largest coal-fired power station and has a generating capacity of 4000 megawatts, producing 26 TWh of electricity in 2010 meeting approximately 7% of the UK’s electricity demand. The plant consumes 10 million tonnes of coal each year and is the largest single source of CO2 in the UK, with annual emissions are approximately 22 MtCO2e, broadly equivalent to all emissions from heating in the commercial and public sectors. It also co-fires coal with biomass and is the largest generator of renewable power in the UK.
Biomass accounts for 15-20% of the plant’s annual fuel use. Drax uses a wide range of both domestic and internationally procured biomass (mainly wood pellets, straw and miscanthus) which is delivered to the site either by road or through Drax’s own dedicated rail wagons. All of the biomass used on site must first be converted to pellets suitable for use at the main power station. While significant amounts of the plants imported biomass will already be pelletised, as part of a tour of the facility we saw the company’s off-site straw pelleting plant which converts locally sourced straw to pellets.
The actual processing of the biomass is through a “processing tower” whereby the biomass pellets are ground into dust, which is then directly injected into the plant’s boilers for combustion (we are not talking domestic boilers here, each boiler is 15 storeys high and weighs 4000 tonnes!). As Drax looks to expand the use of biomass use in the future, it is undertaking R&D into greater boiler efficiencies through enhanced co-firing, with the aim to both reduce emissions and environmental impacts.
Sustainable sourcing of biomass is imperative to ensure significant life cycle emissions savings relative to fossil fuels and to encompass other wider sustainability issues (e.g. biodiversity and land use implications). Drax has implemented its own sourcing criteria but from April 2013 the UK government will require all large generators to meet minimum sustainability criteria in order to receive Renewables Obligation Certificates.
The CCC’s Bioenergy review will be released at the end of 2011. This will include our detailed assessment of investment in biomass power generation, focusing on technical feasibility, economics and availability of sustainable biomass.