NCPA - National Center for Policy Analysis


July 20, 2010

Scotland's wind farms have produced only around half the amount of power they were expected to this year.  The government blamed the low generation levels on unusually calm weather, but critics said the figures showed the danger of becoming too dependent on renewable energy. 

For example: 

  • Turbines are expected to operate at an average output of about 30 percent of their maximum installed capacity.
  • But the average output over five months this year was 17 percent -- just over half the expected average.
  • There have been long spells when virtually no electricity has been produced by any of the country's wind farms. 

"This raises serious concerns about security of supply.  We have always been told that even if it isn't windy in one part of the country, it will be elsewhere.  However, this suggests that is not the case," says Helen McDade, head of policy at the John Muir Trust, which campaigns to protect wildlands in Scotland. 

Stuart Young carried out the research by analyzing data from the Balancing Mechanism Reporting System Website, which the National Grid uses to monitor generation.  The site provides a constant flow of information on output from 1,588 megawatts wind farms in Scotland: 

  • His research showed that for 80 percent of the time between February and June, Scotland's turbines were operating at less than 30 percent.
  • And for almost a third of the time they were operating at less than 5 percent of their maximum output, meaning they were virtually becalmed.
  • Only nine times between February and June had the wind farms achieved 30 percent efficiency for a full day at a time.
  • There were long stretches, such as from May 16 to 29, April 9 to 15 and February 6 to 23 when they failed to reach 30 percent output. 

"At the moment there's not a big enough penetration of wind to cause National Grid a problem, but the more we rely on it and the less we use fossil fuels the more likely there is to be a set of circumstances when -- with very high demand and very low output -- the only thing is to turn customers off," says Young. 

Source: Jenny Fyall, "Windfarms only giving half power," The Scotsman (UK), July 18, 2010. 


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