Analysis of UK Wind Power Generation: report by Stuart Young commissioned by the John Muir Trust

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Stuart Young is the author of these reports:

(He has  reviewed these reports and believes that the conclusions of his findings are as relevant today as they were when written, although all the numbers have changed) .

“Overview of the Scottish Government’s First Annual UPDATE ”“Overview of 2020 ROUTEMAP update” for Renewable Energy

“Gas, oil and coal prices were subsidised by £3.63bn in 2010” Or were they?”                                                      Coal gas and oil subsidy 28 Aug 2012

Analysis of UK Wind Power Generation: report extract from John Muir Trust


Blaven and Marsco, Skye
Blaven and Marsco, Skye

The report, Analysis of UK Wind Power Generation November 2008 to December 2010, is the result of detailed analysis of windfarm output in Scotland over a 26-month period between November 2008 to December 2010 using data from the BMRS (Balancing Mechanism Reporting System). It’s the first report of its kind and draws on data freely available to the public. This data challenges five common assertions made regularly by wind industry and the Scottish Government that:

  • Wind turbines will generate on average 30% of their rated capacity over a year
  • The wind is always blowing somewhere
  • Periods of widespread low wind are infrequent
  • The probability of very low wind output coinciding with peak electricity demand is slight
  • Pumped storage hydro can fill the generation gap during prolonged low wind periods

In fact, the report finds that:

  • On 124 separate occasions from November 2008 to December 2010, the total generation from the windfarms metered by National Grid was less than 20MW (a fraction of the 450MW expected from a capacity in excess of 1600MW+). These periods of low wind lasted an average of 4.5 hours.
  • Actually, low wind occurred every six days throughout the 26-month study period. The report finds that the average frequency and duration of a low wind event of 20MW or less between November 2008 and December 2010 was once every 6.38 days for a period of 4.93 hours.
  • At each of the four highest peak demand points of 2010, wind output was extremely low at 4.72%, 5.51%, 2.59% and 2.51% of capacity at peak demand.
  • In fact, the average output from wind was 27.18% of metered capacity in 2009, 21.14% in 2010, and 24.08% between November 2008 and December 2010 inclusive.
  • The entire pumped storage hydro capacity in the UK can provide up to 2788MW for only 5 hours then it drops to 1060MW, and finally runs out of water after 22 hours.

The report also found that during the study period, wind generation was:

  • below 20% of capacity more than half the time
  • below 10% of capacity over one third of the time
  • below 2.5% capacity for the equivalent of one day in twelve
  • below 1.25% capacity for the equivalent of just under one day a month

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