Wind turbines - going strong 20 years on

Anti-wind campaigners claim that wind turbine performance more than halves after 15 years. Chris Goodall analyses the figures and finds that even 20-year old wind turbines in the UK are still going strong ...

The Renewable Energy Foundation (REF) has made the surprising assertion from the that the performance of wind farms declines rapidly with age.

A study carried out by Professor Gordon Hughes for the REF in 2012 suggested 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."

To put this in everyday English, Professor Hughes is saying that a 15 year old onshore wind farm will typically produce less than half its initial output of electricity.

Few people in the industry would demur from a conclusion that wind farms very gradually lose output but none accepted Hughes's finding that electricity generation falls at anything like the rate he stated.

Wind turbines near Tow Law, County Durham, UK.
© Jonathan Pearson / pearsongraphics via

Serious implications

If true, his finding would have serious implications, as the REF was keen to point out. To achieve the UK's targets for wind-generated electricity, we would have to put more turbines on the ground because ageing wind farms would produce much less power than expected. This is an important topic and I thought it needed more examination.

After meeting REF in early 2013, DECC Chief Scientist David MacKay responded to the study, eventually publicly saying that Hughes' work had serious statistical flaws.

REF has recently rebutted Professor MacKay's comments saying, with some asperity, that his actions are 'extraordinary' and impugning his understanding of econometrics.

Few of us have the detailed knowledge of statistics to say whether Hughes' conclusions follow from the data he has used. I thought it might therefore be helpful if I analysed the individual performance of all the UK's oldest wind farms.

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