Wind Turbine Decline: Not So Fast

The claim that wind turbines have a short lifespan, seized upon by wind power opponents in 2012, itself seems to be failing to stand the test of time.

The latest blow to the allegation comes from researchers at Imperial College London, who say their comprehensive look at the United Kingdom’s onshore wind farms – now comprising 4,246 turbines that generate 7.5 percent of the nation’s electricity – shows “that the turbines will last their full life of about 25 years before they need to be upgraded.”

UK wind farm (image via RenewableUK)

UK wind farm (image via RenewableUK)

The research disputes earlier work from renewable energy critic Gordon Hughes and the Renewable Energy Foundation, which looked at UK and Danish wind farms and concluded that “the economic life of onshore wind turbines is between 10 and 15 years.”

While Hughes found capacity factors declining annually by 5 to 13 percent (percent, not percentage points), the new research says the actual rate of decline is around 1.6 percent. So on average, a wind farm will go from a 28.5 percent capacity factor when new to 21 percent after two decades of operation.

“This trend is consistent for different generations of turbine design and individual wind farms,” the researchers report in the study, published in the peer-reviewed journal Renewable Energy. “This level of degradation reduces a wind farm’s output by 12% over a twenty year lifetime, increasing the levelised cost of electricity by 9%.” The researchers called that decline “not unusual compared to conventional generation technologies.”

Hughes claimed to use “rigorous statistical analysis” in his study, but the Imperial College London researchers say his work actually had a key shortcoming – it used average estimates of nationwide wind speeds to determine the effects of wear and tear on the turbines.

The new research, by contrast, zeroed in to the wind farm level, using 20 years’ of NASA data “to measure the wind speed at the exact site of each onshore wind farm in the UK.”

“In the past it has been difficult for investors to work out whether wind farms are an attractive investment,” co-author Iain Stafell said in a news release about the research. “Our study provides some certainty, helping investors to see that wind farms are an effective long-term investment and a viable way to help the UK tackle future energy challenges.”

While the research disputes Hughes’ findings, it’s in line with an assessment made by WindPower Monthly contributor David Milborrow, whose 2013 look at Danish wind farms concluded that “(p)erformance generally appears to be maintained at a consistent level, with only a slight decline with age –  one in line with other types of power plants.”


  • Reply February 21, 2014


    On talking to a maintenance technician on capital windfarm here a few months back in his words were they cant keep up with the break downs and must be on the verge of bankruptcy with the expense. A bit contradictory to your article I would say…

  • Reply August 20, 2015

    Guy Wind

    1-1.5% seems reasonable from what we’ve seen in our fleet. My only critique of the article is that the NASA data is a reanalysis data set and does not “a measure the wind speed at the exact site”. NASA’s MERRA, and the NOAA equivalent CFSR, models wind speeds in a high resolution grid across the globe. These models take in a number of actual readings from weather stations, balloons, etc and then attempts to reconcile them using physical modeling.

    Don’t get me wrong, these models do a decent job resolving wind speeds and are very useful for long term normalization. However, both MERRA and CFSR can have significant (5-10%) seasonal biases that can be further exaggerated by unseasonable weather. This is why any research should use calibrated on-site readings to adjust the model data.

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