Factcheck: do wind farms increase climate change?

  • 07 Feb 2012, 12:00
  • Robin Webster

You may have seen the rather startling claim in the Mail that

Wind farms can actually INCREASE climate change by raising temperatures and causing downpours, warn academics

Wind farms increase climate change? It's certainly an intriguingly counter-intuitive story. The article also has the sub-headline:

Temperatures can fall by 4C downwind of farms

Wind farms cause temperatures to rise, and fall?

This is a neat example of one newspaper rehashing an article from another - in this case the Mail article is inspired by a report in the Sunday Times covering work by Dr Somnath Roy, an atmospheric scientist from the University of Illinois.

Roy's most recent paper, published in the Journal of Wind Engineering and Industrial Aerodynamics in 2011

explores the possible impacts of such wind farms on local hydrometeorology using a mesoscale model equipped with a rotor parameterization based on data from a commercial wind turbine. Results show that wind farms significantly affect near-surface air temperature and humidity as well as surface sensible and latent heat fluxes.

Remarkably, this appears to mean that wind turbines facilitate the movement of air - as the Sunday Times explain in somewhat shorter words:

….the day ground-level temperature behind the turbines was up to 4C lower than in front. The turbines' blades scooped warm air away from the ground and pushed cooler air above it downwards. At night, when the ground cooled and the air above was warmer, the effect reversed.

[Roy] believed the effects were caused by turbines reducing overall wind speed and creating turbulence. The rotating blades churn the air, bringing high-level air down to earth and lifting up air that had been sitting just above the ground to a much greater height. The resulting vortices can extend far downwind depending on the size and number of turbines.

So, this research uses regional computer modelling to suggest that wind turbines lower temperatures in the region of the turbines a bit in the day, and raise it a bit at night... by moving air around. It did conclude that there could be "significant implications for future energy and land use policy" as use of wind power grows.

Does this amount to 'actually INCREASING' climate change? Possibly not.

What about 'cause downpours'? This conclusion doesn't appear in any of the studies referred to in the Mail article.

It could be sourced to a study published in Environmental Research Letters and cited in the Times article, which looked at the impacts on regional weather patterns of a (hypothetical) "giant wind farm" which could provide 20% of the electricity requirements of the USA.

Such a "giant" wind farm would have impacts on regional weather patterns, but given Britain's current rate of wind build, we're probably safe from giant renewables-triggered deluges.

Still, on the blogs it's just a short step to Wind Farms Cause Global Warming, some Scientists Say.

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