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Sunday, 7 February 2016

Smoke and Mirrors

The UK government has committed itself to significant reductions in greenhouse gas emissions as part of a global strategy to tackle climate change. One element of this reduction is the conversion of a major power station (Drax) from burning coal to biomass. The claim that this is in fact beneficial is open to doubt.

The Drax power station is the largest in the UK and generates between 6 and 7% of the country's electricity. It was built to generate electricity by burning coal, but over the last 10 years has been undergoing a conversion to burn biomass instead. Biomass is organic, plant-based material sourced from forests, forest residues, and dedicated energy crops that are not suitable for other uses.(1)

Coal is a fossil fuel and is a stock of carbon captured from the atmosphere by ancient forests. Carbon flows back into the atmosphere as CO2 when coal is burned thus increasing the stock of greenhouse gases and contributing to global warming. Biomass also contains carbon which has been captured by trees and other vegetation from the atmosphere, and carbon is released when it is burned. However, proponents of biomass use argue that overall significantly less harm arises from its use. In fact some would go so far as to say it is 'carbon neutral'. This claim is largely based on an assumption that biomass is waste material from sustainable forests which regenerate and recapture the CO2 from the atmosphere returning it to the stock held in the biosphere.

Drax claims that 122 kg CO2/MWh (kilogrammes of carbon dioxide per Mega watt hour of electricity generated) is emitted in its biomass units. It compares this to coal emissions of around 1,018 kg CO2/MWh and gas at around 437kg.(2) The Drax biomass conversion is part of the reason the UK's coal use fell below 50 million tonnes in 2014 and this contributed to a 9.7% reduction in UK carbon emissions in 2014, a record for a year with a growing economy.(3) The UK government is so committed to the Drax project that it has guaranteed the conversion cost (4) and is using the data to claim to be reducing greenhouse gas emissions.(5) However, significant questions have been raised regarding the methodology for calculating the impact of biomass burning. For example Biofuelwatch, an independent organisation providing information about the environment, claims that biomass is as harmful to the atmosphere as fossil fuels.(6) An independent analysis of biomass impact in the USA concluded that “for biomass replacement of coal-fired power plants, the net cumulative emissions in 2050 are approximately equal to what they would have been burning coal”.(7) A report by one of the UK government's own departments concluded that “the energy input requirement of biomass electricity generated from North American wood used by the UK in 2020 is likely to be significantly greater than other electricity generating technologies, such as coal, natural gas, nuclear and wind.”(8) A thorough investigation by Climate Brief, a UK-based website covering the latest developments in climate science, came to the conclusion that it was impossible to determine, on the available evidence, if biomass was or was not helping to solve climate change.(9)

The evidence is unclear because there is no standard methodology in use which takes account not only of the direct emissions from the power station but factors like forest growth rates, how much of the biomass is 'waste', what time scale to use, transportation, and what environmental impact the trees would have if not harvested. What is clear is that the directors of Drax, and indirectly the UK government, are using the most favourable assumptions when making their calculations and thus showing significant benefits. This is important not just for this project but because similarly questionable schemes may be operating worldwide throwing into doubt claims about progress in tackling global warming.


(1) Drax website -frequently asked questions http://www.drax.com/biomass/benefits-of-biomass/#sthash.x8x18tvD.dpuf See also diagram at the end of this paper

(3) Drax website policy statement http://www.drax.com/biomass/sustainability-policy/

(4) Department of Energy and Climate Change website https://www.gov.uk/government/news/drax-biomass-backed-by-uk-guarantee

(6) Biofuelwatch website - frequently asked questions http://www.biofuelwatch.org.uk/2013/biomass-faq-2/#C6

(8) Stephenson and McKay Lifecycle Impacts of Biomass Electricity July 2014 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/349024/BEAC_Report_290814.pdf

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