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Samir Succar’s Blog

Do Wind Farms Really Cause Climate Change?

Samir Succar

Posted April 30, 2012 in Solving Global Warming

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A number of news outlets have picked up a recent paper that looks at the local land surface temperature impacts of large wind farms. This has resulted in a number of headlines like “Wind farms can cause climate change” and “Wind farms linked to temperature increase”  (see additional stories here, here and here). 

This wording is deeply misleading in this context and conflates small-scale, local impacts on nighttime land surface temperatures and global climate disruption. Using the same language to describe these two very different phenomena blatantly ignores the profound differences in magnitude, scope and severity that separate them. It’s like equating a bumblebee with Mothra.

If you read the text of these stories, you’ll discover that the paper’s findings don’t match the gravity implied by their silly headlines. For example, the telegraph story linked above says that “[the temperature changes are] much smaller than the estimated change caused by other factors such as man made global warming.”

Professor Sherwood from Cornell is quoted as saying “the wind farms generate gentle turbulence near the ground that causes these to mix together, thus the ground doesn't get quite as cool. This same strategy is commonly used by fruit growers (who fly helicopters over the orchards rather than windmills) to combat early morning frosts.”

Notice that this means that wind farms could actually extend growing seasons by reducing morning frost events. That would be a great ancillary benefit of siting turbine arrays on agricultural land and a welcome alternative to flying helicopters to accomplish the same end. It also gives you a sense of the scope and magnitude of this effect.

Both of these conclusions are supported by earlier research on this topic, which says:

"We find that very large amounts of wind power can produce nonnegligible climatic change at continental scales. Although large-scale effects are observed, wind power has a negligible effect on global-mean surface temperature, and it would deliver enormous global benefits by reducing emissions of CO2 and air pollutants."

Also:

 "it may be comparatively easy to reduce the climatic impacts of wind turbines. Preliminary analysis suggests that turbine designs could be modified to increase the atmospheric efficiency (CP/CD) by several tens of percent and reduce the generation of turbulence by several fold, both of which could be done economically. Additional mitigation of impact might be achieved by siting wind farms such that their effects partially cancel and by tailoring the interaction of turbines with the local topography to minimize the added drag."

So what’s the bottom line?

 Wind-induced turbulence does produce vertical mixing in the atmospheric boundary layer that increases nittime surface temperatures. This is a small, local impact that should not be confused with what is typically thought of as “climate change.” One possibe outcome of this local effect is that you would be able to extend growing seasons for crops grown near wind turbines.  There might be additional impacts that haven’t yet been anticipated, but it is clear that these impacts bear no resemblance in scope, magnitude or severity to global climate disruption. Language matters. Unfortunately, some good media outlets have missed the ball on this one.

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Comments

Ben AinsworthApr 30 2012 02:32 PM

It is not as simple as causing global warming by mixing warme and cold air. None of wing nuts discussing this have raised the issue of the Law of Conservation of Energy. They forgot that you can't get something for nothing. If you take power from moving air it must cause a net heat loss otherwise you have invented the eternal dream of a self powered system with no energy consumption. The conversion of potential energy to kinetic energy in this system of turbines powered by air pressure must cause a reduction in temperature if Boyles Law of Gases is considered in the overall energy cycle. If anything in the down wind area of the wind mill bird killers will be cooled by the loss of heat.
.

Samir SuccarApr 30 2012 02:44 PM

Paul, I don't think anyone is overlooking geothermal ( http://bit.ly/ICOSRh ) or fusion energy sources
( http://www.iter.org/ ). Nothing against H2 and CH3OH either, but those are nominally energy carriers as currently envisioned, not energy sources.

Samir SuccarApr 30 2012 02:57 PM

Ben, No one is getting something for nothing here. I assure you, energy conservation is fully maintained. There is a pressure gradient across the axis of the wind turbine, but that expansion accounts for a small fraction of the energy transfer in the system; the bulk of it is accounted for in the reduction of atmospheric kinetic energy through windspeed losses in the wake relative to the free-stream velocity due to mechanical interactions with the blades. Keep in mind that wind is just indirect solar energy as incident solar flux drives thermal gradients that result in kinetic energy in the atmosphere. Photons in, heat and entropy out. No magic.

Peter KelleyApr 30 2012 03:12 PM

Thank you for helping set the record straight on this. AWEA has a statement out on this today:
http://awea.org/newsroom/pressreleases/120430temperature.cfm

And further analysis on our blog, Into the Wind, by Michael Goggin, titled "Fact check: Flawed science journalism on wind energy":
http://awea.org/blog/index.cfm?customel_dataPageID_1699=16162

-- Peter Kelley
American Wind Energy Association

Major MigraineApr 30 2012 11:43 PM

This is what happens when people worship scientific denial and ignorance, rather than reason, intellect and scientific understanding.

Raymond RaczkowskiMay 1 2012 08:35 AM

Analysis is flawed with root cause and conclusion. This makes all to point fingers and judge. The heat that the wind turbines do produce is minimal compared to positives. Compare this to the heat power plant or nuclear heat produced and released to the water or air.
The root cause of the heat from wind turbines is the underground wires and step up transformers also there. Power distribution is the worst heat producer and 70% power loss. A Wind Farm has a lot of underground wires connecting and surging (over heating) that is not seen. That heat will also effect the water when the wind farms are in the sea. This should be checked to prevent natures harm. Assumption would be minor at worst.
Fortunately AOP has a better solution.
--Raymond Raczkowski CEO
Alpha Omega Project.net

Sandra HaydenMay 3 2012 04:12 PM

The NRDC needs to take another look at fusion energy at the National Ignition Facility. ITER has not even been built yet. NRDC has listened too closely to Stephen Bodner, former head of a rival program at the U.S. Naval Research Laboratory. This matter is too important to leave to an individual with an an ax to grind, as his rants indicate to me. There are other experts, get a second opinion.

Comments are closed for this post.

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