Monday, 13 October 2014

Wind farms perform better than we feared

Some commentators have claimed that the performance of wind farms will decline catastrophically with age. For instance, a report by Prof Gordon Hughes for the Renewable Energy Foundation claimed that the “normalised load factor for UK onshore wind farms declines from a peak of about 24% at age 1 to 15% at age 10 and 11% at age 15”. That implies an annual worsening of about 5% and would presumably be due to mechanical wear. 

It would greatly reduce the long-term value of wind farms both economically and as sources of low-carbon electricity.

Fortunately a more recent study, Staffel and Green, 20 13, suggests that it isn’t true. This is an extremely detailed study which draws on very large quantities of data about both weather and wind farms. The authors show that, though wind farm performance varies considerably:

  •  The initial load factor is 28.5% not 25%.
  •  The annual performance loss is about 1.6% not 5%.

This is good news for investors in wind farms and for the climate.

Hughes, Gordon, 2011: The Performance of Wind Farms in the United Kingdom and Denmark. 2012, London: Renewable Energy Foundation. URL:

Staffell, Iain, and Green, Richard, 2013: How does wind farm performance decline with age? Renewable Energy. Volume 66, June 2014, Pages 775–786. URL: DOI: 10.1016/j.renene.2013.10.041.

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