• A new study has found that wind farms generate below 20% of their supposed output for 20 weeks a year, and generate below 10% for 9 weeks a year.

• Wind farms, on average, only exceed 90% of their rated output for 17 hours a year.

• Though the government acknowledges that wind farms produce much less energy than their sticker capacity would suggest, the report shows that even the average production (of around a quarter of capacity) is extremely misleading about the amount of power wind farms can be relied up to provide.

Wind farms are extremely volatile, with outputs fluctuating by five percentage points over short periods of time, a report based on new data by the Adam Smith Institute and Scientific Alliance has found. These findings suggest the UK’s energy infrastructure can never be reliant on them in any significant way.

Specifically, the study found that wind farms generate below 20% of their supposed output for 20 weeks a year, and generate below 10% for 9 weeks a year. Wind farms, on average, only exceed 90% of their rated output for 17 hours a year.

The paper, “Wind Power Reassessed: A review of the UK wind resource for electricity generation", looks at previously unexamined wind speed data reported by anemometers located at various airfields, used as a proxy for nearby wind farms, and concludes that UK wind farms, on average, exceed 80% of their supposed output for less than one week every year.

The study also looks at the short-term (30 – 90 minute) variability of wind generation and reveals swings in output are far higher than is normal from conventional energy generation, such as from gas or nuclear plants. Swings of five percentage points of output are not uncommon, which contradicts the claim that a widespread wind fleet installation will smooth variability. There are frequent but unpredictable periods where wind energy generation fails for days on end.

The report will severely undermine the case for a move towards yet more wind generation because it suggests that wind can never be a major, reliable source of energy for the UK. It also suggests that the UK's drive to reduce its carbon footprint through expanding wind power is misguided. Wind power is so unreliable and intermittent that it makes much more sense to look to nuclear and gas as better low emission alternatives to the status quo.

In his research, the report’s author Dr. Capell Aris looked at 6.5m individual recordings from 22 sites in the UK and 21 from Ireland and the continent.

Commenting on the report, Dr Aris said:

The current reliance on wind energy to reduce carbon dioxide emissions is inefficient and compromises energy security. Power output of the studied system is below 20% of nominal capacity for over 20 weeks of the year, and below 10% for 9 weeks.

When we study those periods when production falls below 20% of rated capacity, more than three quarters of this occurs in periods longer than 12 hours. Each winter has periods where wind generation is negligible for several days.

The situation across the whole of northern Europe is much the same, so a Europe-wide power grid would provide no extra security; the study demonstrates that interconnectors will not solve wind’s intermittency problem.

Head of Policy at the Adam Smith Institute, Ben Southwood, said:

Wind farms are a bad way of reducing emissions and a bad way of producing power. They are expensive and deeply inefficient and it seems like they reduce the value of housing enormously in nearby areas. We probably do want to reduce carbon emissions, because according to the IPCC global warming will begin to slow economic growth in one hundred years, but nuclear and gas power are our best ways of doing that until cheap and efficient energy storage options are available on a vast scale to smooth the highly variable output of renewables.

Director of the Scientific Alliance, Martin Livermore, said:

This study is a graphic illustration that wind turbines cannot provide a secure supply of electricity, no matter how large the distribution grid.

Notes to editors:

For further comments or to arrange an interview, contact Kate Andrews, Communications Manager, at kate@adamsmith.org / 07584 778207.

The Adam Smith Institute is an independent libertarian think tank based in London. It advocates classically liberal public policies to create a richer, freer world.

The Scientific Alliance was formed in 2001 to encourage politicians to make policy on the basis of scientific evidence rather than lobbying by vested interests.