A stroll through a wind farm may be a breezy experience. Now it turns out that extra drafts, created by swishing turbine blades, can change the weather.
As well as extracting energy from the wind, wind turbines swoosh air around. Fernando Portée-Agel, from the École Polytechnique Fédérale de Lausanne in Switzerland, and colleagues, investigated the impact of the extra drafts, measuring changes in temperature and humidity beneath a scale model of a wind farm, situated in a wind tunnel.
They found that downdrafts and updrafts from turbines often superimpose, especially when wind turbines are placed in neat rows. This affects the way that heat and moisture are lost from the land, the scientists explain in the journal Environmental Research Letters.
Sometimes changes are positive, as when crops are grown under a wind farm in Iowa, USA, where the wind turbines cool the air in the summer and help crops to thrive. But in other cases the drying of the land may make crops wilt, or alter the balance and distribution of species living under the turbines.
Luckily these weather changes are localised, and occur on large wind farms. With thoughtful design (such as staggering the turbine layout) the weather changes caused by wind farms can be minimised, or mitigated (by adding irrigation systems for example). For wind farm developers this is an extra headache, but with planning, wind farms could improve our weather.
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