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Wind farms can cause change in local temperatures

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October 5, 2010

Wind farms can cause change in local temperatures (Photo: Gizmag)

Wind farms can cause change in local temperatures (Photo: Gizmag)

The benefits of wind farms in terms of global climate change are well recognized but according to researchers at the University of Illinois they can also affect local climates as well. The researchers observed that the area immediately surrounding a wind farm is slightly warmer at night and slightly cooler during the day compared to the rest of the region. The discovery could allow for strategies to mitigate those effects in areas where they are undesirable, or take advantage of them in others.

The research was led by University of Illinois professor of atmospheric science Somnath Baidya Roy, who first proposed a model describing the local climate impact of wind farms in a 2004 paper. But until 2009 when he met Neil Kelley, a principal scientist at the National Wind Technology Center who had collected temperature data at a wind farm in San Gorgonio, California, for more than seven weeks in 1989, no field data on temperature were publicly available for researchers to use.

Turbulent discovery

Analysis of Kelley’s data corroborated Roy’s modeling studies and provided the first observation-based evidence of the daytime cooling and nocturnal warming effects of wind turbines. The cause of the temperature change identified by Roy’s models was the mixing of warm and cool air in the atmosphere in the wake of the turbine rotors. As the rotors turn they create turbulence, which pulls upper-level air down towards the surface, while surface air is pushed up, causing the warmer and cooler air to mix.

Roy says the question of whether nocturnal warming or daytime cooling will be the predominant effect depends on the wind farm’s location. In areas where the winds are typically stronger at night, such as the Great Plains region of the U.S., the nocturnal warming effect would be stronger, while regions where daytime winds are stronger will experience a stronger daytime cooling effect.

According to Roy, the nocturnal warming effect could be used in farm areas, such as the Midwestern U.S., to provide some measure of frost protection or even to slightly extend the growing season.

Dealing with the temperature change effect

The researchers also identified two possible strategies to mitigate wind farms’ impact on local climates. The first is to develop low-turbulence rotors that would result in less vertical mixing of the air and would also be more efficient for energy generation. We’ve covered a number of technologies that aim to do just that, such as flexible flaps attached to the trailing edges of a rotor blade or the insect-inspired turbines from Green Wavelength.

The second strategy simply involves locating the turbines in areas that already have a turbulent atmosphere so the consequence of turbulence from the rotors in minimal. Using global data, the researchers identified regions where the temperature effects of large wind farms are likely to be low because of natural mixing in the atmosphere.

“These regions include the Midwest and the Great Plains as well as large parts of Europe and China,” Roy said. “This was a very coarse-scale study, but it would be easy to do a local-scale study to compare possible locations.”

What's next?

Using data from and simulations of commercial rotors and turbines, Roy’s group will next generate models looking at both temperature and moisture transport. They also plan to study the extent of the thermodynamic effects, both in terms of local magnitude and of how far downwind the effects spread.

“The time is right for this kind of research so that, before we take a leap, we make sure it can be done right,” Roy said. “We want to identify the best way to sustain an explosive growth in wind energy over the long term. Wind energy is likely to be a part of the solution to the atmospheric carbon dioxide and the global warming problem. By identifying impacts and potential mitigation strategies, this study will contribute to the long-term sustainability of wind power.”

The team’s paper will appear in online early edition of the Proceedings of the National Academy of Sciences this week.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
5 Comments

I was in the Columbia Gorge in Oregon this Summer and they have 100's of those things on both side of the river in Oregon and Washington and I noticed they were have a WAY cooler Summer then normal? Could that have anything to do with it? LOL! :-)

mrhuckfin
6th October, 2010 @ 04:32 am PDT

Is it only a matter of time until someone calls this mixing of air "thermal pollution" and questions its affect on the health of local flora and/or fauna?

Bruce H. Anderson
6th October, 2010 @ 06:06 am PDT

I would think that temperature stabilization would be a benefit and not a problem. I also wonder what the temperature variances were like there before the turbines were put in place. The sites are chosen because of very specific conditions. Those conditions could have lead to those temp. differences without the turbines. Some testing in future installation sites might be a good idea to get a benchmark. I wonder if they did this as part of the 2004 work. Nothing was mentioned.

Raum Bances
6th October, 2010 @ 10:47 am PDT

This is so utterly implausible that I actually laughed out loud.

Upper level air is not "cooler", especially never if wind is present. It is at a lower pressure. Bring a parcel of air from an upper to lower level - and you'll discover that as it's pressurized to match the lower level, it's temperature will also correspondingly match as well.

To a recreational open-cockpit pilot, the temperature change due to atmospheric pressure is very obvious. Launch in a T-Shirt, and you'll be freezing cold by just 1000ft.

The only possible way this could be remotely plausible, would be if a ground-level inversion were present (a fleeting and very-rare-in-windy-conditions phenomenon where the temperature of air at a higher level is different to what would be expected by pressure change alone). Even then - it would be rare, if ever, that it would occur any place where a wind farm is operating, at a wind farm altitude, and even if it did, it would last for a mere hour or less on such a rare if even possible occasions - and would exhibit the opposite effects to those described in this article anyhow.

Don't get me wrong - there does exist warm air, and it does mix (narurally - all the time). That's where nice puffy clouds come from - but if there's any wind around, that's what's triggering the thermals - not the few spinny things dotted about.

If there's any kind of genuine research taking place here - I would contest that it is a social reseach project, designed to test the general gullibility of the population when presented with unsubstantiated yet remotely plausible climate related research. How far can they push the envelope in the face of an ignorant public not concerned to ask for facts and evidence?

I'm not holding my breath to see their 7 weeks of 21-year-old temperate data readings published! If nothing else - this is the red flag demonstrating the hoaxiness of this article. Who in their right mind would beleive that a professor needed to find someone who breifly measured some temperatures 21 years ago to corrobate his model? Did he not himself think to step away from his computer and pick up a thermometer at any stage? I would suspect he probably did, and probably subsequently burried the evidence that illustrated he left PV=nRT out of his model by mistake...

christopher
6th October, 2010 @ 08:42 pm PDT

Well Dah. We knew that already! its a man made wind brake. Like a row of trees or buildings it has an affect. Wind brake effects have been known since antiquity. they don't block wind but cause turbulent effects behind the wind brake. These effects on crops have been known since the 1920's. The effects are mostly beneficial for crops, as these chaps note. Nice to know the obvious has been confirmed by data.

Wesley Bruce
7th October, 2010 @ 04:18 am PDT
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