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Can large wind farms tweak weather downwind?

By Peter N. Spotts / June 24, 2009

Wind turbines near Judith Gap, Mont. Scientists are asking if regional collections of large wind farms could affect weather patterns half a world away, and, if the changes are significant, how the farms can be managed to reduce such effects.

Melanie Stetson Freeman/Staff/File

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A battle over a wind farm in our backyard – off the island of Martha's Vineyard – has shown that folks can raise a host of objections over unintended consequences, real or imagined.

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They've included hazards to boaters, hazards to endangered migratory birds, hazards to aircraft flying between the Vineyard and the mainland, and of course, hazards to the property value of big-buck homes with scenic views of Nantucket Sound. Oh yes, one can't forget the installation of transmission lines to link the turbines to the utility grid. And that's just for one relatively small wind farm.

Now researchers are looking at another potential "unintended consequence" – the likelihood that collectively, groups of large wind farms in one region could alter weather patterns downwind of the turbines in another region.

So far, evidence suggests that large collections of wind farms could have small but measurable effects on atmospheric circulation patterns, cloudiness, and temperatures over substantial distances.

"If you have a couple of wind farms over a 10-kilometer patch in the Midwest, that's not going to make some kind of global impact on the weather," says Daniel Kirk-Davidoff, an atmospheric scientist at the University of Maryland, College Park, who works on the issue. But if the whole Midwest "is somewhat roughened over a large area, then you could imagine having a large-scale impact on the atmosphere."

At this stage, he says, the results from his and other studies are reassuring: It looks as if any regional or global effect would be tiny, especially compared with changes anticipated from global warming. And the effects are small compared with the benefits to the climate of giving fossil fuels – especially coal – the heave-ho in favor of energy sources that don't release greenhouse gases, noticeably carbon dioxide.

But instead of packing up their computers and data and calling it a day, he and his colleagues are trying to refine their estimates with an eye toward wind farms of the future – "how to design wind farms in ways that make them innocuous," he says. One such study, in pdf form, is under discussion and review for publication at the website for the journal Atmospheric Chemistry and Physics.

Wind energy's potential

The impetus for such work: Studies highlighting the potential role wind turbines can play as climate-friendly sources of electricity. For a peek at the most recent estimates, journey over to the journal Proceedings of the National Academy of Sciences for a free pdf of the formal research paper published earlier this week.

The study was conducted by scientists from Harvard University and the VTT Technical Research Centre of Finland.

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