Saturday, October 6, 2018

Do Wind Turbines Enhance Global Warming? No!

There were a series of headlines in a variety of media outlets this week suggesting an unfounded and unphysical claim:  that wind turbines might contribute to global warming.  Some examples below:

The Associated Press
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The Harvard Gazette
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MIT Review
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These stories are based on an article entitled “Climate Impacts of Windpower,” by Dr. David Keith and Dr. Lee Miller, in which they ran the WRF model (the one I use) and added the impacts of a very large number of wind turbines over the central U.S.  They found that the wind turbines caused a .24C warming over the U.S. due to the mixing of warm air down to the surface.


Now why does mixing of the wind in the vertical produce surface warming?  Doesn't temperature cool with height?

The key issue is that frequently the surface is cooler than than the air above.  This is particularly true at night when the earth radiates heat to space more effectively than the air above.  In these cases we can get an inversion, air warming with height.  Mixing due to the disturbance of the air flow by the spinning blades can mix warmer air to the surface.

This effect is no stranger here in the Northwest--have you seen the fans around orchards in eastern Washington?  They are used to mix warmer air down to the surface to reduce freezing temperatures when the buds on fruit trees are vulnerable.  Some vineyards have them as well.
 "Orchard-Rite" Wind Machines
So one can cause small net localized warming at the surface by mixing the low-level air, but you are NOT warming the atmosphere as a whole, but simply moving warm air around.

Thus, wind turbines are not producing any net heating to the atmosphere and thus doing NOTHING to increase global warming.   And the only time there is doing localized warming is when the surface is relatively cool!

Wind energy is am important technology in our quest to move towards renewable energy and a potent complement to solar energy,  particular at night and in cloudy regions.   It is unfortunate that some careless media reporting left an inaccurate impression of negative climate impacts of wind energy.






19 comments:

Peter Lemme said...

wouldn’t the wind turbine extract energy from the free stream, a net cooling?

Bruce Kay said...

You think thats funny. Check out Roy Spencer blog where he devotes an entire screed to excoriating a small roadside wind turbine installation that in his words "steals" energy from the passing cars and trucks.

I suppose it does but jeez, you really gotta be some special sort of libertarian to pull the guns out over it!

Unknown said...

Temperature inversions occur when there is little wind near the surface, not enough to turn a wind turbine. So the whole premise is pretty absurd. It's like those beliefs that solar panels are weakening the sun by stealing it's energy. Unfortunately, these attacks on renewables work in some communities because of the poor quality of education in large parts of this country.

Larry said...

I noticed that in an AP story, a result of thinking qualitatively vs quantitatively. Especially distressing in these times. Journalism schools (well, all sources of learning) need to do better. Good for you, jumping on this!

Ansel said...

Too many talking heads without a science background!

I admit that the windmills generate some noise and occasionally whack a bird, and can be an eyesore. For this reason, solar power is my first preference. For windmills, I prefer locating them in already-developed farmland instead of on high ridges or offshore. And the farmer can profit by charging rent or royalties. A win-win.

Ian Reed said...

Had a couple people share this and had to go into a very lengthy explainer of how the atmosphere works, and how this whole process of mixing, and temperature profile works.

Really bad reporting, leaving out key details to push a one sided point.

C.P.O. said...

Cliff, could you post your thoughts on I-1631? I know it's not as good as the measure that failed, but is it worth voting for?

BMFH said...

Effective Bird Killers but it green tech

Eric Blair said...

"Unfortunately, these attacks on renewables work in some communities because of the poor quality of education in large parts of this country."

No, the reason why renewables are suspect in many people's minds is that they're a wasteful use of tax dollars, are inefficient in the extreme, and do an abysmal job of replacing the energy sources used currently. Until they become a truly equal replacement source in terms of cost and efficiency, many will continue to view them as crony capitalism schemes.

John McBride said...

In addition to your blog post, Cliff, you'll need to tackle ScienceNews which "contributes" to the confusion:
https://www.sciencenews.org/article/how-wind-power-could-contribute-warming-climate

BAMCIS said...

There is now that year 2030 doom and gloom report circulating just before the elections. Is there science attached to that or is it left out because the average citizen won't be able to understand it?

Yes there is also at home for our consideration the I-1631 which is being combated in the same manner as anything a large swath of industry does not approve of. Astroturfed and treated as a "New tax on hard working Americans". Just like with soda. Is soda really a grocery, though? Does it have any nutritional value or is it just a treat?

As for energy, is a few cents increase in energy costs a big deal? How about using less energy to offset it? Might be the point, but I dunno. I am just some guy from the Internet so what do I know. Many people will oppose it just due to the government having such a bad track record of how these revenues are allocated. So it will be up to "Responsible Private Enterprise" to save the plant. Or to adjust to the aftermath more than likely.....

Anyway, I notice more increase in the cost of cellular data and cable/home ISP than anything I-1631 could manifest. There usually is no benefit to using less of it. The bill goes up regardless if all or none is used and has to be paid or done without.

Unknown said...

If the study being reported on was weak wouldn't it make more sense to criticize the study rather than "the media"? Attacking reporters for reporting bad science doesn't make sense. It seems to me criticism would be better directed at the publisher, who presumably should be a better gate keeper than the generalist lay press. Moreover, I searched "do wind turbines cause global warming?". All the top hit were articles in "the media" explaining how the study was really about surface temperatures not climate, just like this blog entry. So this isn't "the media" at all, so much as some media doing a better job of reporting nuanced facts than others.

James said...

Doesn't mixing tend to warm the air near the surface even if there isn't a temperature inversion, because as the air falls it compresses and warms up? For instance when Los Angeles experiences Santa Ana winds, the air starts relatively cool and heats up as it descends from the mountains. And when I read the forecast discussion provided by my local NWS office, I sometimes notice that the temperature forecast depends on how much mixing there is, with mixing tending to bring warm air to the surface, and I don't think this always means that there's an inversion.

Andrew Kennelly said...

We need more people with STEM backgrounds in journalism and in government. If someone with a Ph.D. in a legitimate scientific discipline ran for office, I would be tempted to vote for him or her regardless of party affiliation, unless he or she were some sort of eccentric crank.

Eric Blair said...

People with STEM backgrounds won't run for office or seek jobs in government, because they're too intelligent to get involved in those occupations.

audioskeptic said...

Wow, just WOW. Somebody actually argued that taking energy out of the atmosphere and converting it to electricity WARMED the atmosphere?

My goodness. You have great patience. Dr. Mass. I think my first reaction would be to scream "CONSERVATION OF ENERGY YOU (*&(&(&".

SharplyFocused said...

@Eric Blair:
"No, the reason why renewables are suspect in many people's minds is that they're a wasteful use of tax dollars, are inefficient in the extreme, and do an abysmal job of replacing the energy sources used currently."

Can you cite your evidence for this assertion please or are you just expressing your opinion (which you are entitled to do)? I'd be interested to see you reference power purchase prices for wind versus other resources and for you to illustrate how the wind power being generated today does an abysmal job. Alternatively, edit your post to add "In my opinion..." at the beginning.

SharplyFocused said...

Thanks Cliff for helping to correct the record. Addition info for those interested can be found here: https://www.aweablog.org/fact-check-no-wind-turbines-not-cause-climate-change/ with links to some additional technical rebuttals.

This pseudoscience has been performed for close to a decade now, ever since the wind farm parameterization (which has its own uncertainties) was introduced to the WRF. Don't get me wrong, genuine studies with realistic scenarios should (and are) being run to understand wake and mixing impacts on local microclimates, and we do need to completely quantify the LOCAL changes in heat and moisture flux due to increased mixing, mainly to counter this type of lunacy, but also because we want to mitigate unintended consequences like those that hydro power had on fish. However, the community is reasonably sure that the net impact will be a net positive to agriculture in areas with large amounts of turbines since it will lengthen the frost free season slightly. And since plants transpire during the day, the impact of the moisture flux will be minimal since the surface layer is generally unstable at that time anyway. Compare that to what a coal plant does to get perspective here.

carlbuick said...

Wind turbines extract kinetic energy out of air...not thermal energy. This kinetic energy taken from the slowing down of the air moving through the blades. Moving air has kinetic energy. That energy is partially used up to move the blades and the air slows down after it passes the the blades. There is no transfer of heat in this process. The moving blades turn generators which make electricity which eventually gets used in motors, lights and electronic devices. These all put energy back into the atmosphere in the form of heat. Originally the energy input to move the air is from the sun. There should be no effect on global warming other than that it decreases the use of fossil fuels.