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Wind farms whisk up weather

wind farm

Tomorrow's weather will be windy (Image: Wind Energy Development Programmatic EIS)

Wind farms might affect local weather, and slow down the wind that drives them, U.S. research has found.

The research led by Dr S Baidya Roy from Princeton University is published in the current issue of the Journal of Geophysical Research: Atmospheres.

But the effect is quite small and nearby farmers don't need to worry, said an Australian wind farm expert.

The researchers adapted a standard climate model to predict how a hypothetical wind farm would affect local meteorological conditions in the Great Plains region of Oklahoma state.

They predicted that the turbines, which harness the wind's energy to produce electricity, would slow down wind behind the propeller hub.

They also predicted that the turbines would create vertical eddies, causing air from the ground to mix with air higher up. The eddies would dry and heat the air on the ground particularly during the normally still early morning, the researchers said.

Weather at ground level

Dr Peter Coppin, director of the wind energy research unit at CSIRO's atmospheric research division, described the research as "a bit of a curiosity and an interesting problem".

But he said the effect on agriculture would be negligible, and people living near wind farms didn't need to worry, as wind farms would have little impact on weather conditions near the ground.

A wind farm "acts like a tall forest", said Coppin, creating a windbreak. But he said unlike forests the farms had little or no effect on air moisture.

He also said that wind turbines were spread quite widely so their turbulent wakes of wind didn't affect other turbines.

But he said it was important to look at turbulence when placing wind farms. Cliff top turbulence could do "nasty things" to wind turbines, such as cracking the blades, he said.

Coppin described how a wind farm in the southern island state of Tasmania had to be moved back 100 metres from a cliff edge because of problems with turbulence, and to protect soaring birds, which could have had problems dodging the blades.

When the wind drops

In Australia less than 1% of energy comes from wind farms. So generating more, better weather forecasting techniques were needed, Coppin said.

He said his own research was focused on improving forecasting so the proportion of energy gained from wind power could be turned up when the wind was strong.

If the wind dropped, the source of electricity suddenly vanished, he said. This was a problem in Australia because he said the wind was best out in the middle of nowhere. And he said switching between energy sources was harder if there wasn't another energy source around.

Tags: environment, climate-change, science-and-technology, engineering