Common Eco-Myth: Wind Turbines Kill Birds
by John Laumer, Philadelphia on 04. 6.06
It's a given that anytime we post a story on wind power someone is going to comment that "turbines kill birds," suggesting that wind power may therefore be unacceptable. Compared to what? Hitting birds with automobiles (along with turtles, groundhogs, and deer)? Birds caught by feral cats? Birds colliding with buildings or phone towers? Quite possibly, a higher mortality will be attached to the transmission wires needed to get the wind power to market. Why, then, do many associate bird mortality only with wind turbines? We hope to get to the bottom of this "death by turbine" myth hole, and point to the factors that can actually be managed though public involvement.
Our hunch is that the Altamont Pass California wind turbines, reportedly the site of some of the highest bird mortalities associated with any US wind farm, and using what is now an antique turbine design, are at the root of the widespread association of bird mortality with wind turbines in general. Now might be a good time to have a glance at this site, to get some perspective on the hundreds of raptors killed per year by the Altamont turbines.
If extrapolating the "worst case" rate is a bad idea, what about the "average" wind farm bird mortality figures? Even average rates, which are much lower or course, need to be looked at carefully.
To help our understanding of turbine hazards to birds we'd like to make an analogy, to your bicycle. Turn your bike upside down or put it in a work rack, set it to the highest gear...the one you use to go fast on a level slope.... and now move the wheel slowly with your hand. The chain moves rapidly with only a few degrees of wheel rotation. This symbolizes today's cutting edge 1.5 mW turbines, which have a very large surface area of blade exposed to the wind and a gearbox that turns the dynamo quickly while the blades move slowly. Birds dodge these slow moving blades relatively easily.
Now put the bike in the lowest gear...the one you use to climb hills...and move the wheel with your hand fast enough to turn the chain as fast as before. That symbolizes the 20-year-old "bird-o-matic" wind turbine design. Small blades with small surface areas have to turn rapidly to overcome the magnetic force of the dynamos, which generate electricity.
Recapping: small blades, low surface area, lots of dead birds possible; very big blades, with large surface area exposed to wind, very few dead birds.
High capacity turbines are a relatively recent commercial product. Consequently, any field study of "avian mortality" done on a wind farm constructed prior to approximately the year 2000 (maybe a bit later in the US) is inappropriate for estimating bird mortality based on modern turbine designs.
Whether by intent or because older studies are more common, opponents of wind power will have cited bird mortality data from studies done before 2000 and, to make their point, are likely to focus on studies done on wind turbines erected in high exposure situations: e.g. in migratory pathways, at mountain passes, near nesting areas, and so on. Those are the numbers that get quoted at public hearings, published in the media, and that therefore underlie the collective consciousness about wind turbine hazard to birds. Not unlike what happens to people who constantly see fires crashes and shooting on the local news and come to think that what they are seeing is far more common than it really is, it all comes down to a risk communication problem.
Let's frame the threat with a simple risk management equation: Mortality equals hazard times exposure, or M= H * E. Individual hazard (H) is the probability of Tweety being smashed to bits if it flies into a wind farm. The last four paragraphs helped establish that H is getting smaller, not bigger. This means average bird mortality is also getting smaller and will likely continue to do so. We remain optimistic that additional technological means will be discovered to further reduce "H" and therefore "M." It might be as simple as avoiding any surfaces that would attract perching or nesting.
The exposure factor in the mortality equation ("E") is a bit more complex. "E" is obviously highest where birds migrate, breed, and feed in flocks near wind farms. There are very windy places where "E" is low all year: a dearth of birds. And there are certainly windy places where "E" is high only during a brief migratory period, or for a limited number of species which fly at a certain elevation.
Certainly the siting process needs to steer wind farms away from places where it can be shown that "E" is relatively high. Designers continue to work on lowering "H," while citizens, naturalists, municipalities with permitting or zoning authority, and scientists work to ensure that "E" is acceptably low. This is how it works. Once the turbines are up there's no chance to alter "H" for at least another 20 years. "E" can change year to year, however, depending on something as basic as which crops are planted nearby. For this aspect mitigation planning can be a part of permit approval.
Statements about "average" bird mortality ("M") do not well inform the debate over siting unless you get at the "H" and the "E" individually. By now it should be obvious that, like politics, all exposure is local. Citing an average "E" factor without some expert interpretation is not helpful. Having said that: here we go.
In the United States, cars and trucks wipe out millions of birds each year, while 100 million to 1 billion birds collide with windows. According to the 2001 National Wind Coordinating Committee study, “Avian Collisions with Wind Turbines: A Summary of Existing Studies and Comparisons to Other Sources of Avian Collision Mortality in the United States," these non-wind mortalities compare with 2.19 bird deaths per turbine per year. That's a long way from the sum mortality caused by the other sources.
For an excellent overview of all the major bird mortality categories we suggest you visit this site page maintained by the American Wind Energy Association
i'll tell you why that myth is spread, its because LIPA and all these other power corporations don't want to spend there money on research when they could just make a few press releases about the evils of green energy. and what really gets me angry is that the people getting angry at the wind mills are probably 95 percent meat eaters. they're all hypocrits...
Hear Hear!!! Time the anti-wind a**wipes find another piece of propaganda. The Dutch also did a nice study on this, it can be found here:
http://www.planetark.com/dailynewsstory.cfm/newsid/31542/story.htm
Hey, I know, you anti-wind wackos can latch onto the idea that turbines will slow the planet's rotation down, causing untold climatological disasters! I think Sci-Fi Channel has a movie of the week coming up about that. :D
Thanks for making this known.
I would add that right now the off shore Cape Wind project on Cape Cod is in danger of being killed because of myths like this. I encourage those who care to support Cape Wind.
Even if a few birds die imagine the amount of wildlife saved from decreased amounts of pollution. People also don't seem to care if their airplanes destroy birds.
Nice!
I wrote something about this on my blog a few months ago (http://sheagunther.org/blog/?p=156), watch out for the anti-wind nuts to pour out of the woodwork to argue this one.
Thanks so much for this article, and I'm in total support of wind energy.
Although I must say that I'm not in support of using phrases like "probability of Tweety being smashed to bits" and references to "bird-o-matic" wind turbines which will only upset people already sensitive to this topic and in turn may keep people like myself from forwarding this article along to those sensitive people.
Just my .02 cents.
Yeah, it seems to be an argument designed to either a) allow wealthy liberals to engage in NIMBYism while pretending that they're really concerned about wildlife, or b) allow antienvironmentalists to attack environmentalists as hypocrites.
Rock on. Now go educate the ignorant masses instead of the choir.
"Now go educate the ignorant masses instead of the choir."
There's nothing we'd like more.
Don't be shy, spread the word, send journalists our way, forward this article to non-choir-persons..
Hopefully it'll rank high in Google for "wind turbines kill birds".
John, thanks for a good sound article. It's unfortunate that the cleanest of clean power has acquired a bad name so unfairly.
I think, however, that you should revisit that bike-gear analogy. You said that a high gear involves fast chain movement with only a little wheel movement. That's backwards; you get that result in a low gear.
Think of it this way. Suppose your smallest sprocket (high gear) is a 13-tooth, and your largest sprocket (low gear) is a 28-tooth. In low gear, 13 links worth of chain movement produces one full wheel rotation; in high gear, less than half a rotation.
I suspect this would become easier to rephrase if the you got clear in your mind which part of the crank/wheel system is analogous to which part of the turbine/generator system. In the bike, the big spinny thing is the load, and the small part is the power source; in the turbine, the opposite is true.
Keep up the good work.
Dom
Misinformed nature lovers are only half the problem. Some of the best sites for wind have humans living on them, and the NIMBY crowd complains about the 'ugliness' or 'noise' generated by wind turbines. Now noise isn't really an issue unless you're standing right next to these things, but you can't argue with ugly. I think they're beautiful myself, and would love nothing more to open my drapes in the morning and see a 250 foot prop quietly generating the energy that runs my coffee pot.
This post has been submitted to Digg.com (and has generated some discussion over there too).
If you want to vote for it, follow this link.
"but you can't argue with ugly. I think they're beautiful myself, and would love nothing more to open my drapes in the morning and see a 250 foot prop quietly generating the energy that runs my coffee pot."
From my completely non-scientific survey, I'd say that younger people tend to like the sight of wind turbines more than older people.
It could be that the "ugly" factor will recede with time, as more and more people are familiar with wind turbines from a very young age and as the population in general becomes more eco-conscious.
I bet the people of Denmark and certain regions of Germany smile more on windy day! Once people realize wind is a natural resource that creates money and jobs for their area, they might change their minds.
Helix based wind turbines such as Aerotechture (http://www.aerotecture.com/) and Quiet Revolution (http://www.quietrevolution.co.uk/) don’t kill birds. I know the designer of Areotechture, he’s seen birds fly straight through the turbine with out being injured. Not to mention they look cooler than common prop turbines.
'Ugly' may depend on your viewpoint, as well. I remember reading that when Khrushchev was visiting the USA, and was riding along the Jersey Turnpike, he saw the proliferation of active smokestacks and said it 'looked beautiful'. To him, the evidence of significant industry was a sign of economic strength. He might also have been referring to the implication that there was bountiful worker employment in the region.
In my opinion, I find wind turbines beautiful for very similar reasons.
It seems to me that it's more the NIMBY's than the power companies themselves. LIPA is actually trying to put in some turbines off the south shore of Long Island, but people are complaining that it will "ruin their view" The whole bird excuse is really just a mask for the "ugly" argument. How about instead of windmills or no windmills, a view of windmills or smokestacks? Suddenly they look a whole lot better.
Wrong: "Wind turbines don't kill birds."
Right: "Wind turbines rarely kill birds."
5 bucks says birds die more from when they are sitting on the turbines, then the wind moves the turbines slightly, so the bird slides off and falls to the ground, than they do frum running into the turbines.
I was sitting at a StarBux some time ago with a friend, we were sitting outside. As we were sitting there a bird flew into the window, snapping its neck killing it instantly, it fell into my friends lap... I say BAN STARBUCKS NOW, STARBUCKS KILLS BIRDS.
I love the concept of wind power and live in a very windy spot (the Columbia River Gorge). I had heard the bird mortality info before and it made me second guess wind power.
I think the reason the bird death risk gets so much traction is due to the impact of water turbines on salmon & steelhead from hydroelectric something we all thought was a pure, ‘free’, non-impacting power source 30 years ago.
Net-net: I think explaining how/why bird death risk is NOT the Achilles’ heel of wind power will go a long way towards making us salmonoid huggers get on board.
I have been working with my Professor Bill Leithead, who is an expert in wind turbine design in europe. With regards to bird's death caused by wind turbine, the percentage is so small compared those creatures killed by colliding into window panes and building structures.
With abundant wind energy over the coast and high offshore wind speed, it is important that researchers and developers take advantage of such event to harnass the power for the grid. The cost of wind energy is so little, with an average life expectancy of about 30 years, thus makes a good investment opportunities for investors.
Wind energy is environment-friendly, so why not?
Um, these windmills are doing us all a servce. Haven't they heard of avian flu?
Near where i live they are planning to build a windfarm, which has faced much opposition & only recently been under threat of being canned because of potential damage to a rare species of bird..
The thing is though, the people protesting against the windfarm are wealthy landowners who don't want their precious view destroyed by turbines. It saddens me to think that they only now are prepared to jump on the enviromental bandwagon to save some bird, nevermind the gas guzzling SUVs they all drive..
If it's all the meat-eater, wind-hating folks - wouldn't they want the birds to die? It provides many meals! Since you know, I come across anti-windites all the time. That's the most ridiculous thing - if anyone's complaining about death tolls of 2.19 birds per turbine, it's PETA.
The problems with the wind turbines is all the extra ugly pylons that have to be built. Usually across areas with the most natural beauty.
It makes sense to produce power closer to big cities. Windmills are fine if they are offshore, and undersea transmission lines are used.
Regarding birds, the report actually references transmission lines as the biggest killer.
eric okeson, I'd love to see a bird flying through an aerotecture. It's a high-solidity design that would require the bird to be carrying a chainsaw to pass through it.
Birds will collide with anything; it doesn't have to have the illusion of being open space.
Very useful and informative post! I would love to see bird deaths per kilowatt for wind power ranked against bird deaths per kilowatt for coal power. Don't forget, global warming is an extremely effective bird-killer.
How can you say that rotor blades move slow when you don't give us the math? A blade of 20 m moving 20 times a minute is moving about 150 km/h. Birds will be hit. We have this problem i Norway. Soaring eagles can not easily avoid this.
==== author's response follows ====
If you have a math background you obviously appreciate that the speed of the blade segment decreases with closeness to the hub. Citing the speed of the outer-most arc as the "H" factor would be biased. Perhaps the midpoint would be the right speed? When you say eagles "soaring" that would be only one behavior that contributes to "E": also to be accounted for would be diving, taking flight, wheeling, etc. Which behavior would be prevalent at mid-rotor elevation range. For this we would have to rely on an experienced ornithologist for guidance, relative to the proposed site. I am supposing that "soaring" would expose eagles to the blades at mountain passes in critical hunting and breeding habitats: exactly the places that wind farms should not go. We are not far apart it seems to me.
Odd that no one gets up in arms about automobiles and roadkill.
Unfortunately, wind turbines DO kill BATS. In large quantities. Check out http://www.batcon.org - they regularly report on detailed studies on this.
There are things that can be done about it. It's not that wind power and bats are incompatible, but rather that the power companies aren't interested in spending a bit more to protect the bats.
I eat meat and am in favour of windfarms... is this allowed?
I just finished a physics course in "Energy Sources in the Early 21st Century." It became abundantly clear that with China and India industrializing rapidly and peak oil happening between 2005-2010 (2010 if you include strip-mining Alberta for the tar sands) that there is absolutely no option besides wind power.
-Solar is too expensive (for now)and needs the exlusive use of huge tracks of land
-Fission will run out of fuel in less than a decade of providing the planet's needs
-Fusion isn't likely to produce power in industrial quantities until after 2050 (if ever)
Unfortunately for the forseeable future it's going to be coal, wind, and hydro.
Canadians like myself have to learn to use 50% less energy in the next four decades. This means home and business thermostats will have to be set at 14C or 57F during the day, and lower still at night; and every vehicle will need to get hybrid efficiencies.
The bird argument may slow windmills down, but reality will set in sooner or later.
-Mike
i can't believe you wrote such a long article about this. those people are morons and the world will go on without them. i believe in protection of endangered species by film. in other words, i believe in natural selection and humans documenting the process all the long way. :)
Author -
You sort of admitted to but failed to address that 'average' issue one poster brought up. You can't use the arguement that prop speed is decreasing. Is the average (distance from tip to hub) speed increasing or decreasing?
Also, if E equals exposure, then you are increasing E if you are increasing the number of windpower stations. The whole issue to begin with is that you going to add to your kill count by adding the stations.
==== author's response follows ======
RPM's have gone down absolutely. The props got longer but the outer most tip of the new props go relatively slow in radial velocity compared to middle of the older prop blades. In some cases blades are fewer as well.
To model total risk we have to decide if the hazard is "faced one turbine at a time" or cumulatively, which will be based on spacing in 3 dimensions. Here I am out of my skill set and will have to leave it to those with more field experience and knowledge of bird behavior.
My point was not to construct an operating model, real time, in a blog but to help deconstruct a meme that made little sense. Bottom line is that bird kill rates (mortality) can be diminished if people work hard to lower both H and E, using best practices and common sense to guide the siting and design processes.
One last tidbit. Reaction to risk always is shaped by the extent to which it is voluntary: e.g. we tolerate 50 thousand people getting killed in traffic accidents each year because each of us "knows" that we are in control of how we drive; but we are very intolerant of a far lower hazard created by another party or a factor out of our control. 'Bird kills at my house are ok but not by a wind farm owner'.
That being said, I'm in favor of windpower and think that the nay-sayers and NIMBYs are throwing up a smokescreen.
> Citing the speed of the outer-most arc as the "H" factor would be biased. Perhaps the midpoint would be the right speed?
Okay, let's do that, but with real numbers. A Vestas V100 has a rotational speed of 13.4rpm and a blade diameter of 100meters. Let's use the midpoint, so we have a diameter of 50meters, a circumference of 157meters, swept 13.4 times per minute, times 60 minutes/hour = 126km/h at the blade midpoint. (252km/h at the tip) How, exactly, does this make it safe? I do, however, take issue with the "midpoint" idea... The swept area is a function of the square of the radius. Therefore, the midpoint of the blade represents the one-quarter/three-quarters swept area boundary. In simple english, on a Vestas V100, on three quarters of the swept area of the blades, the speed of the blades is greater than or equal to 126km/h. I don't like those odds if I'm a bird, no matter what your bike chain says.
==== author's response follows =====
Great job of starting a working model definition for "H". As my post asserted however, "M" is a function of "E" as well. And you and I are probably not very good at intuiting how a bird will respond to "H or really understand why. Same for bats. One hypothesis we could pursue to tease out "E" in detail would be: "past a certain rotational average velocity, certain avain species are unable to percieve, and therefore unable to avoid" moving obstacles". "E" becomes random after a certain speed in otherwords. This is quite similar to how so called "mosquito repellants" work. They don't really repel at all. What does happen is that the insect's heat detection sensory organs are disabled by binding with a repellant vapor, so the squitos are no longer able to orient to a mamalian heat source. As a result, only a few bugs "collide" without skin.
For bats an "E" would be far more complex due to their looping flight patterns as they follow prey and because of their use of echo location and possible interaction of sonar with blade or rotor noises.
I wonder if you can get over the ugly arguement by making wind towers look like windmills at the local mini-golf. No one argues with mini golf.
1. If the speed closer to the hub is slower on large blades, it is on small blades as well. The larger blade area on giant new turbines presents a much greater danger, sweeping a vertical air space of over an acre.
2. The industry cites the information from one old study at the Stateline facility in Washington. They prevent any independent research on the issue, as they now also do about bats after studies found thousands being killed at one facility in the Appalachians.
3. Since it is obviously an issue of cost vs. benefit (thus the strained argument that wind power saves more birds (or bats) than it kills), then where is the evidence of the benefit?
4. Wind power facilities also disturb nesting, particularly with prairie birds. That can have an even more negative effect on populations than outright killing.
5. The most attractive places to wind power developers are often popular flyways. Since little is known of local details about migratory pathways, especially of night flyers, developers resist making adequate preconstruction studies. That arrogance has contributed to the state of Vermont apparently planning to reject a proposal on East Mountain.
6. If anyone looks ridiculous, it's environmentalists attempting to downplay the negative impacts of their chosen industrial development.
==== author's response follows =====
These are sensible arguements that deserve serious attention. However, not all the cited Exposure factors apply equally and some may not apply at all depending on the proposed site.
Here is the best rebuttal to this argument I have heard. I believe it is from wind expert, author, Paul Gipe.
The 3,000+ wind turbines operating near Altamont Pass (CA) would have to operate for more than 500 years to be responsible for the same number of birds the Exxon Valdez killed in less than one week.
So, which energy source do you prefer?
altamont pass is in the middle of the highest populations of some rare and spectacular species - such as the golden eagle. it doesn't take many collisions to decimate this species. perhaps there needs to be a call to replace the old-style bird-manglers w/ the new and improved, bird-friendly turbines at this site - or maybe at least those turbines which are most responsible for bird killings. that might be a wise preventive measure for wind power proponents to take while these raptors are still amongst us. 50,000 human deaths per year in auto collisions does next to nothing to affect our survival as a species, but we are talking about a significant disruption to the entire population of some species. if we begin to speak in terms of percentages of total numbers of a given species, then we can assess the risk that we are assuming more clearly.
Why is there no mention of species and their density? I think the comparison to car windows etc. is uninformitive if we don't know if if they are the same birds that we are worried about during migration through windfarms
Ok. I am beating a dead horse here but an argument to put turbines on hawks ridge in Duluth should not be based on the number of dead Cedar Wax Wings found in NE Minneapolis.
Everyone seems to be pulling out their calculators so I thought I'd do the same. You say that everyday living in the US is estimated to kill 100-1000 million birds per year in the US, so I'll take the average of 550 million. Over a population of 295 million that's 1.85 birds/person/year.
I just thought that put the 2.2 birds/turbine/year in a bit of perspective.
PS To other commenters, please do not blend vegetarianism with wind turbines, I strongly suspect that this type of hybridisation does not help the cause one iota.
As a personal "anti windfarm a** wipe," I'd like to speak up for the educated side of us. Most people who are opposed to wind farms are realistic enought to realize that the birds killed from wind warms are stupid. The big reason to be against wind farms is the disappearing prairie land. Only 2 percent of prairies exist today. They are the most endangered ecological system in the U.S. Once you destroy a prairie by tilling the land, or altering it, it is never the same. Prairies can not be recreated by man either.
Wind farms should be placed in placed that aren't endangered. I believe other energy sources should be used before we turn to wind power. Try biomass, solar, or water.