Exactly How “Green” are Wind Turbines?

Using the wind to produce energy is considered by many to be an environmental panacea. Consider the words of Greg Vitali, a member of the Pennsylvania House of Representatives:

Wind energy is better for the environment than coal, natural gas or nuclear energy. Wind turbines operate pollution free, do not add to climate change and use very little water.

At first glance, this sounds reasonable. After all, wind turbines don’t emit carbon dioxide, so they are not contributing to the horrible “global warming” that is supposed to happen this century. They also don’t seem to consume much. They just sit there, twirling in the breeze, making electricity for us to use. It’s not surprising, then, that wind power is the fastest-growing source of new electrical power in the U.S.

As the video above shows, however, wind turbines do have an environmental impact – they can kill flying animals. Of course, a video of one or two birds being knocked out of the air by a wind turbine is no cause for alarm. The real question is, “How often does this happen?” If a few hundred birds are killed each year by wind turbines, you can legitimately say that their impact on bird populations is relatively low. However, a recent study indicates that more than just a few hundred birds are being killed each year by the turbines that produce wind power.

Dr. K. Shawn Smallwood, an ecologist at the University of California, Davis, reviewed bird fatality reports from wind farms across North America. He then developed a model that would help him estimate the number of bird deaths that would occur each year as a result of wind turbines. His results were stunning. Using the amount of wind power produced in the U.S. in 2012 as his benchmark, he estimated that 573,000 birds would be killed by wind turbines each year! 83,000 of those birds would be raptors, which includes endangered or threatened species like the the California Condor and the Northern Spotted Owl.1 To me, those numbers are staggering, and since wind power is growing quickly, they will probably increase significantly over the next few years.

Dr. Smallwood’s paper also estimates the number of bats that will be killed by wind turbines, and those numbers are equally alarming. He estimates that 888,000 bats will die from wind turbines every year. This is especially troubling, because there are many endangered bat species. Ironically, the Atlanta Journal-Constitution reports that a single Indiana bat (which is endangered) found in Georgia has caused the delay of $459 million worth of road work, but no wind turbine installations are being delayed over worries about endangered bats!

While it was not surprising to me that birds are killed by wind turbines, I found it odd that bats can be killed by them. After all, bats have a sophisticated sonar system that puts the best human technology to shame. With their sonar, they should have no problem avoiding the rotating blades of a wind turbine. However, according to a study that was done five years ago, a large number of the bat fatalities associated with wind turbines seems to be the result of the low-pressure zones that form near the turbines.2

While the bats can detect the turning blades of a wind turbine with their sonar, they cannot detect the fact that there is a lack of air near them. As the bat flies near the turbines, it flies into a low-pressure zone, which causes trauma to the lungs. This trauma, usually called barotrauma, ruptures the capillaries in the lungs, resulting in internal bleeding. In the study, the authors found that 90% of the dead bats they examined showed signs of this kind of trauma.

Now please don’t get me wrong. I am not saying that wind power is bad for the environment. I have no idea, since Dr. Smallwood’s study is the first one I have seen that tries to estimate the total amount of animal deaths caused each year by such turbines. It’s possible, of course, that his model is wrong. It’s also possible that based on our growing knowledge of the interactions between birds, bats, and wind turbines, we can produce something that makes the wind turbines less deadly to flying animals.

My point is that environmental issues are not as simple as they seem. At first glance, it seems obvious that wind power is an environmentally-friendly way to produce electricity. It doesn’t emit pollution, it doesn’t consume many resources, and it doesn’t produce harmful byproducts. It also doesn’t contribute to “global warming,” or “climate change” as it is now known. However, it does slaughter a lot of birds and bats every year. Until some detailed analyses are done to determine whether or not the positive aspects of wind power outweigh the negative ones, it is clear that we should move more slowly when it comes to large-scale implementation of this supposedly “green” power source.


1. K. Shawn Smallwood, “Comparing bird and bat fatality-rate estimates among North American wind-energy projects,” Wildlife Society Bulletin 37(1):19–33, 2013
Return to Text

2. Erin F. Baerwald, Genevieve H. D’Amours, Brandon J. Klug, and Robert M.R. Barclay, “Barotrauma is a significant cause of bat fatalities at wind turbines,” Current Biology 18(16):R695-R696, 2008
Return to Text

12 thoughts on “Exactly How “Green” are Wind Turbines?”

  1. There are non-environmental problems, too. Wind turbines are heavily subsidized–they are not profitable on their own, yet there are many companies turning a “profit” off their manufacture, installation and use. Two words: wealth transfer.

    One other environmental and safety problem is who becomes responsible for the abandoned structures once a company goes out of business? The fail-safe/lockdown mechanisms that keep the rotor from spinning won’t work indefinitely once maintenance ceases.

  2. I consider wind turbines a form of visual pollution. They wreck the visual scenery wherever they are placed.

  3. Wow, this is very interesting. Looks like so-called “green energy” programs might backfire in ways people hadn’t thought. I’d like to see some future research into the downsides of solar energy (other than the obvious problem of clouds, nighttime, etc.) as well.

    1. As I understand it, Nathaniel, one of the big problems with solar power is efficiency. Since solar panels are still relatively inefficient, they take up a lot of space. Since land in the U.S. is expensive, that makes solar power on a large scale very expensive.

  4. The other issue with solar energy, is that it is a VERY dirty process to create the solar cells. The cost is coming down as new processes and technology is being developed, but still dirty process. It is even dirtier than standard IC manufacturing.
    Until a new technology is found for more efficient, clean energy, we need to keep a balance of all power production, or cut our consumption.
    Every single method of power production has a negative environmental impact.

  5. I’m with Talan. Solar energy requires toxic chemicals to produce the cells. Solyndra created lots of cadmium and lead contaminated equipment.

    Wind energy takes a lot of rare earth metals for producing the strong magnets in the latest generators. Fossil fuel and nuclear generators can use less material due to the centralized nature of them. You just need a lot of copper.

    I would personally love to see our grid powered with nuclear power for baseline production and fracked natural gas for peak production. Save the oil and (gasified) coal for automobiles.

  6. That’s what I’ve always been thinking. Nuclear power is much more efficient than coal and oil, and is more “green” in many respects. Of course, the downside is that it is more dangerous, but with time and technological development, it should become safer. I strangely remember my father telling me they said the same thing many years ago…

  7. I think the biggest problem with nuclear is that it’s a PR disaster. At heart, the technology running cars is bomb technology. Ignite something as fast as possible, create a shock wave with the power to shift a half ton lump of metal. But it’s not a bomb powered engine, it’s an internal combustion engine; so very neat and sanitary.
    If only people realized that nuclear reactors have less in common with the Hiroshima bomb than cars do with TNT, they might stop thinking with their endocrine glands and start to examine the situation rationally.

  8. Exactly. It’s the same thing with food irradiation. Lobbyists are going to do what lobbyists are going to do…

Comments are closed.