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Carbon Dioxide "Savings" from Wind Farms.

Dr Mike Hall V 6 January 2009

The basis on which the calculation of CO2 savings from a wind farm is made has changed over time. This note sets out the historical development and current practice. 

• Corporate Responsibility Reports in the 1990s demonstrate that 1 tonne of CO2 saved could be claimed for every megawatt hour (MWh) of electricity generated (see PowerGen CRR)

• During the mid-1990s this fell so as to reflect the displacement of coal generation to a value of 0.86 tonnesCO2/MWh. This became the norm and is still used by many wind farm companies and the British Wind Energy Association (BWEA).

• Also about this time the DTI (now the BERR) stated in Wind Energy Fact Sheet 14 that the grid-average mix should be used rather than the coal displacement figure. At that time this was 0.654 tCO2/MWh based on a 1993 blend of power stations. Since then many dirty coal plants have been replaced by cleaner gas power stations with a consequent change in the mix.1

• Since 2004 DEFRA have been using a grid average mix figure of 0.43 tCO2/MWh 2

• This also became the practice of the Carbon Trust which uses the same figure of 0.43 tCO2/MWh 3

• Ofgem also uses 0.43 tCO2/MWh for converting Renewables Obligation Certificates into Emissions Trading Scheme Credits 4

• The current use of 0.43t/MWh has been confirmed by the Advertising Standards Authority (ASA) in several rulings since December 2005 against Renewable Energy Systems Ltd and NPower Renewables as the figure to be used for calculating the lifetime savings of a wind farm. Since mid-2007 the BWEA have been negotiating with the ASA to try to agree a figure acceptable to the industry.

• In May 2005, the Government’s Sustainable Development Commission refers to a figure of 0.36t/MWh by 2020. 5

• In a press release in Autumn 2007 from BERR, Malcolm Wicks, the Energy Minister, used a figure of 0.37t/MWh to calculate the savings expected from the Fullabrook Down wind farm (Devon) consented under Section 36 of the Electricity Act. This is now the norm for the department of BERR as confirmed in replies to questions in the House of Commons January 15th 2008. 6

• In 2005 in its Climate Change Review, DEFRA 7 used a figure for CO2 savings of 0.27 tCO2/MWh for the year 2010 a figure confirmed in a written answer by the Energy Minister in the House of Commons 8. Although the value of 0.27t/MWh refers to ALL renewables, 85% were anticipated to be wind power. Thus the figure attributable to wind is likely to fall between 0.27 and 0.43, probably about 0.35tCO2/MWh. Finally in November 2008 the BWEA, after lengthy negotiations with the ASA, agreed to change their web site and inform members that the figure of 0.43t/MWh should be used for CO2 emissions saving calculations. See web site 9. It should be noted that this remains a considerable exaggeration as thise figures make no allowance for (i) CO2 emissions during fabrication, transport, erection and maintenance of the turbines and infrastructure which in itself may require a pay-back time of 4 to 33 months depending on the site 10, or (ii) spinning reserve and back-up power stations, the need for which will increase as the wind carpet grows.

  CONCLUSIONS: It is clear from the above that changes in the energy mix have reduced the claimable CO2 savings of wind farms by two-thirds in the past 15 years. However, even these figures are exaggerated as they make no allowance for CO2 expended in manufacture and installation, the mining of iron ore and limestone for steel and cement manufacture, the liberation of CO2 from peat which is damaged during construction, and the need to provide back-up of up to 90% of the installed wind capacity. This last critical issue has been confirmed recently by the Director of the UK Renewable Energy Strategy (Mr Christopher Barton) when he said ‘the intermittency issue is not an insurmountable one, albeit that surmounting the problem comes at a cost, for example, there will need to be greater overall generation capacity in the UK [our emphasis] as you introduce more intermittent generation11. This was even further emphasised by Paul Golby the Chief Executive of E-on UK) when he pointed out that Britain would need to construct 44 gigawatts of EXTRA coal and gas-fired plant if the 2020 target was reached, just to back-up wind12. Eon confirmed this in a technical note to the House of Lords Economic Affairs Committee in June 2008.13 The Oxford economist Dieter Helm summed it up when he said, ‘..we would need to have more conventional power stations to allow us to have ‘windmills’. What an Alice-in-Wonderland world’! 

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COST MPLICATIONS: Due to the closure of 18 aging nuclear reactors (9.83 GWe)14 and six coal-fired power stations due to the EC Large Combustion Plants Directive (8.62 GWe)15, the UK will lose 18.46 GWe of its generating capacity by 2023. These have to be replaced. In addition, the UK Government plans to build 7,000 wind turbines (4,000 onshore and 3,000 offshore) amounting to 35 GWe. On top of this (see above) Paul Golby has stated that 44 GWe of coal or gas will have to be built to back up this wind carpet making a total of 97 GWe of new plant by soon after 2020. The cost estimate for the wind element is £100 billion, to which must be added at least a further £93 billion for 62 GWe of back up and direct replacement (£1.5 bn/GW) and a conservative £15 billion for Grid construction and reinforcement for renewables. Business and banking is, therefore, going to be asked to find £100bn + £93bn + £15bn = £208 bn over 2/3 of which is in pursuit of carbon reduction rather than electricity security per se.

1. See - http://www.dti.gov.uk/energy/renewables/publications/pdfs/windfs14.pdf
2. See DEFRA’s  Guidelines for the Measurement and Reporting of Emissions by Direct Participants in the UK Emissions Trading Scheme (June 2003). Protocol A1 of this gives (p. 20) a figure of 0.43kg CO2 per kWh, i.e. 0.43 tonnes per MWh,
3. See http://www.thecarbontrust.co.uk/carbontrust/low_carbon_tech/dlct2_1_6_4.html
4. See Ofgem, ROC Register End user guide (July 2003 Version 2.0), p. 7.
5. Wind Power in the UK. Sustainable Development Commission, May 2005, Section 4.5, page 35
6. House of Commons Written Answers to questions 175695 and 175696 from Mr Paterson MP, 15-1-2008
7. DEFRA. Review of the Climate Change Programme, p.42 para 6.9 and footnote 17. Savings expected are 2.5 million tones of carbon = 9.17mtCO2. Divide this by the expected generation from renewable [33.6 terawatt hours] give a saving per MWh of 0.27 tonnes.
8. O’Brien M. HoC Hansard Written Answers, 2nd February 2005, column 929W
9. Refer to http://www.bwea.com/edu/calcs.html  for current recommendation
10. Milborrow D (1998). Dispelling the myths of energy payback time.  WindStats Newsletter, Vol. 11 (2)
11. House of Lords European Union Committee 27th Report, ‘The EU’s Target for Renewable Energy: 20% by 2020’, Volume II:, Evidence (HL Paper 175-II), Page 3, question 12, Published 24th October 2008
12. Quoted by Mark Milner in The Guardian, June 4th 2008, E.ON warns over backup for renewables
13. ‘Requirement for thermal generation to back-up wind capacity’. Note from Eon (UK) to the HOL Economic Affairs Committee inquiry into the Economics of renewables. June 2008
14. See http://www.world-nuclear.org/info/inf84.html
15. See http://www.berr.gov.uk/files/file37586.pdf, The role of coal in electricity generation, David Porter, CEO Assn of Electricity Producers, Nov. 2006,