Clean Power

Published on May 9th, 2014 | by Michael Barnard


Wind Security Guards, Bald Eagles, Bats, High School Wind Manufacturers… (WINDPOWER 2014)

May 9th, 2014 by  

Originally published on Energy & Policy Institute.

Meredith MacDonald kicks off this day’s update. She’s a wind turbine deployment tech in Ontario. She worked night shift as a security guard contracted to keep an eye on local wind farms at night during construction. She loved wind energy so much she started blogging, and taking pictures, and making decals and generally being entranced and enthused. It didn’t go unnoticed and now she’s employed full-time in the industry she loves. She recently won the AWEA #iheartwind competition with this submission. Yeah, that’s a snow-covered wind turbine blade a couple of hundred feet off the ground. Consider this my call-out to AWEA to get her on stage to tell her story and take a bow next year.

That wasn’t the only great part of the kickoff by any stretch. I was lucky to sit next to 40-year raptor expert Joseph Platt of Power Engineering and had the opportunity to ask him some questions. A big takeaway was that bald eagles in every state have recovered to 2-3 times the threshold for endangered species, and that bald eagles just don’t fly much where wind turbines are placed. Bald eagles just aren’t endangered and haven’t been for years, and the incidental take permit is very reasonable.

After iconic birds, it was endearing kids. A team of Grade 7 students came on stage to talk about how they won the Kidwind competition by building the best-producing wind turbine in 11 days. My heart melted, and then I went and talked to a few teams of electrical and mechanical engineering students competing in the more rigorous DOE collegiate level of the competition. These college kids were using sophisticated blade profiling techniques, rapid prototyping and carbon-fibre strengthening along with milled aluminum, casting and rapid-fab electronic boards to achieve their goals. Various iterations of horizontal axis wind turbines were on display as well as repeats of some of the deadends of the wind generation experimentation: vertical axis wind turbines and downwind blade pass turbines were the two that leapt to my attention. Very reasonable if you only want to charge a cellphone, which was the target goal, along with many engineering constraints that made the job more challenging.

Another piece of great news was the continuation of the theme that so-called low-wind turbines are becoming dominant in many wind regimens and greatly expanding potential generation. This chart shows the amazing land area in the US that is now considered economically viable for wind generation given the wind resources. Many other charts showed constraints and inhibitors such as cities, radar, endangered species ranges and the like. Very interesting, but the sheer expanse where it now makes sense to consider wind farms is a poorly told story of innovation.

Bats and Wind Turbines

Bats are the new eagles it seems. At the conference at least, attention has moved on from avian mortality to concerns about bat species. Part of this is because biologists who actually care about species as opposed to individuals are all clear that the average wind turbine annual mortality rate of one in 86,000 birds just isn’t a concern and endangered species mitigations and siting care are well understood. It’s business as usual to not site turbines in such as way that they put endangered birds at risk and wind turbine siting is not impaired by this care.

Bats are different though. Birds are short-lived with very high mortality; the population swings between 10 billion and 20 billion birds in the US every year as birds are born and die over nesting, migration and wintering cycles. They only have a year or two of breeding. Bats on the other hand mature only after a year or two, then have very few babies annually. A female bat killed in the third year of its life might deprive the species of 15 or more years of births.

This is a very important distinction because it means that any given bat death is more significant than any given bird death from a species survival perspective. There’s good news, which is that wind turbines only kill around 200,000 bats annually per the current studies and that 78% of those are unendangered roosting tree bats. However, the dynamics of longer lives and lower fertility mean that even the relatively small impacts of wind turbines are of concern for roosting tree bat long-term survival. What’s more of a concern is there are three types of bats likely to be moved on to endangered species lists due to white-nose syndrome: the northern long eared, little brown and tri-colored bats. The trend to lower-wind speed sitings due to better turbines overlaps with this in an interesting way. So far there is one proven method of reducing bat mortality, which is to raise the speed at which wind turbines start generating power to 5 m/s or around 11 mph (18 kph). This works fine in high-wind resource sites where there is little generating impact by not using the least powerful wind speeds, but as more of the generation load is achieved at lower wind speeds, the impact on total generation increases. Other mitigations are being addressed but there are few solid studies to base decisions on.

That all said, there’s another very good bat story in here. A major wind farm in the US has a major bat colony of a species at risk in a cavern nearby. It’s been studied more intently than any mix of bats and turbines and the wind farm is only killing 0.03% to 0.05% of the bats annually, which is insignificant regardless of other concerns. Wind turbines just don’t kill that many bats compared to population levels either.

There was one concern that was fairly thoroughly shot down, although not resolved everywhere in the real world yet, that of radar clutter. It turns out that old radar sends out a bunch of radar beams at the same time, listens to the reflections and then treats the signals as a unit, more or less. This means that a bunch of horizon clutter from wind turbines occludes planes flying above and near them. Modern radar with better signal process uses more fine-grained radar beams to sweep individual volumes of space, and then does high-resolution analysis which keeps the regions separate. This means that wind turbines are seen where they are and don’t get in the way of seeing anything else. Lockheed Martin’s transportable and quickly deployable TPS-77 system has been solidly proven on every other type of clutter and now fully tested on wind farms. It was the basis of removing military radar concern restrictions in the UK that unlocked 3 GW of permitting for wind farms which are now under construction. They’ve sold about 170 of these world wide and while individually they aren’t cheap, they are fraction of the cost of a GW of wind energy construction. The technology is much more necessary for military installations where multiple, high-speed, rapidly maneuvering bogies with no transponders accurately identified is the requirement. For civilian radars, transponders and much more stable flight paths reduce the need, but don’t eliminate it. This is where the biggest drag will come from in the end. While radar systems world wide are approaching or in obsolescence, replacement of the technology won’t happen overnight. Still, a very good news story on a frequently raised concern, one with an actionable and negotiable solution.

Department of Energy Vision for Wind Energy

The Department of Energy shared its draft updated vision for wind energy with the conference. The primary short-term takeaways were very encouraging. First off, it calls for 10 GW of wind to be added to the grid annually for the next ten years. As the new AWEA Chair-elect, Susan Reilly, pointed out in the panel session, the US industry put in over 10 GW in both 2012 and 2013 so that volume isn’t a problem. And the person directly engaged in getting the needed transmission in place was clear that transmission for the plan was viable. The feeling I was left with was that it was a low-ball estimate, and that given the right demand structure and long-term stability for financing, significantly exceeding the plan would be easy.

The day proceeded on to a very compelling but too sparsely attended session on how to gain social license for wind farms with permitting committees, town councils and local citizens. John Davies of Davies Public Affairs had the best presentation on the approach, tactics and key points I’ve seen. A few gems:

  • Opponents consider a wind farm the same as a coal plant
  • NIMBYism starts from a good place but there are irrational NIMBYs who are opposed to any change
  • Everything we do is driven by stories and the stories we share. Stories pull, not push.
  • “Just 3–5% of a community will change a community” … for better or for worse

I won’t get into the tactics, as that requires a much more detailed set of material to do justice, but the question and answer was compelling. The question was put to the panel “Does the wind industry take this seriously enough and are they investing enough in it?” The answer was a resounding no — which, while it was coming from a panel who took this very seriously, resonated with my observations of wind farms in various states around the world. The wind industry still hasn’t come fully to terms with the reality that global social license doesn’t mean that they have site-specific social license, and aren’t spending the time, attention and money necessary to stop significant project delays and potential project abandonment when things go wrong. A lively set of discussions ensued on how AWEA could leverage its position to get CEOs engaged in this directly.

The day closed with a screening of the great documentary Scaling Wind from Utah, which is brilliantly framed to bypass conservative objections to wind energy and state its advantages to things that they care about. This was a deep necessity in very Red State Utah, but a sophisticated approach to understanding how to frame the message was created over years and embodied in the video by its creator, Ed Stafford, who among other roles is a Professor of Marketing at a Utah business school named after a Republican politician. The money shot was George W. Bush in 2006 telling the NREL that America needed to achieve 20% wind energy for reasons of energy security, so start working on how to do that.

The documentary screening was followed by another networking opportunity. I spent a solid block of time exploring how to work through the thickets of Chicago School of Economics perspectives on wind energy with newly minted AWEA Research Director Michael Goggin. His analyses of what is actually happening and takedowns of disinformation by opponents have been rock solid, and his shift into the leadership role is well deserved. Expect great things from him in the coming years.

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About the Author

For the past several years Michael has been analyzing and publishing reports and articles on decarbonization technologies, business models and policies. His pieces on electrical generation transformation and electrification of transportation have been published in CleanTechnica, Newsweek, Slate, Forbes, Huffington Post, Quartz, RenewEconomy, RenewablesInternational and Gizmag, as well as included in textbooks. Third-party articles on his analyses and interviews with Mike have been published in dozens of news sites globally and have reached #1 on Reddit Science. Much of his work originates on, where Mike has been a Top Writer annually since 2012. He also has published a climate-fiction novel, Guangzhou Future Tense.

  • JamesWimberley

    Has any work been done on learning? For a short-lived bird species, this isn’t likely, but longer-lived bats and vultures might learn to avoid wind turbines. Cats, for example, mostly leant to deal with low-speed road traffic.

    • I haven’t seen much of anything on that. For oceanic waterfowl however the evidence is that they treat wind turbines like anything else that stick up out of the water and fly around them. One North Sea radar study saw one bird impact out of millions and significant diversions.

      Eagles react differently according to an expert I was speaking with last week as well. Bald eagles have been observed avoiding a wind turbine when the blades are moving but not when they are still. Golden eagles apparently don’t make that differentiation.

  • mike_dyke

    If a small sonar generator was fitted to the middle of wind turbines which masked the blades to bats by returning a big echo to them (in the same way as the radar story did for old systems) would that make the bats think that it’s a big fixed surface and so avoid the blade area?

    • Up to a point. Various approaches to this have been suggested and some tests started but there is only one paper on it published so validation is low. What is known is that it’s tough to get coverage of the full blade span with this with diminishing effectiveness further from the hub. And as the majority of the swept area is nearer the tips this is a problem. I’ll be gettting to a deeper dive on this area soonish because it appears to be one of the most important real environmental concerns which will impact wind turbine siting. Birds get more attention from the public because they are prettier but impacts are negligible outside of edge conditions.

      • mike_dyke

        So it looks like we need to move the sonar generators to the tips without affecting the balance of the blades. Short range Wifi connection between sonar generator (in hub) and the speakers on the tips?

        • Hard to say. It’s actually ultrasonic that they use, and the higher the frequency the lower the distance traveled by the noise. The device is also non-trivially sized so putting them on the middle or tips of the blades is problematic. It’s also unclear what the impact of the fairly high-speed apparent wind on the ultrasonic emissions would be. They might dissipate it too much at source of emission.

          What might be more interesting, but has different challenges is radar. It has been observed for a long time that bats tend to shy away from operating radar at airports and the like. A study was done specifically for this and found reduced bat numbers in Scotland. This has an advantage over the ultrasonic approach of very low attenuation of effect.

          Both appear less effective and more restricted in terms of placement and use than merely curtailing turbine cut in, and curtailment is something that is within the grasp of every modern wind farm immediately upon it being operational. And as the problem is typically experienced only a few times a year during migration and specific conditions, you don’t have to curtail all the time or even all turbines. It’s an operational choice. That has downsides of course, because they have to be disciplined about the operation rather than just passively running the deterrent, but given that ultrasound or portable radar sucks electricity to operate, they would probably only be turned on when needed and since the output is undetectable to humans, might malfunction without anyone noticing.

          Solutions are imperfect.

          Excerpts from the ultrasonic paper.
          “Our findings suggest broadband ultrasound broadcasts may reduce bat fatalities by discouraging bats from approaching sound sources. However, effectiveness of ultrasonic deterrents is limited by distance and area ultrasound can be broadcast, in part due to rapid attenuation in humid conditions. We caution that an operational deterrent device is not yet available and further modifications and experimentation are needed. Future efforts must also evaluate cost-effectiveness of deterrents in relation to curtailment strategies to allow a cost-benefit analysis for mitigating bat fatalities.”

          “The deterrent devices used in our study consisted of a waterproof box (,45645 cm, ,0.9 kg) that housed 16 transducers that emitted continuous broadband ultrasound from 20–100 kHz”

          Excerpts from the Scottish radar experiment;

          “From July to September 2008 aerial insects at 16 of these sites were sampled using two miniature light-suction traps. At each site one of the traps was exposed to a radar signal and the other functioned as a control. Bat activity and foraging effort per unit time were significantly reduced during experimental trials when the radar antenna was fixed to produce a unidirectional signal therefore maximising exposure of foraging bats to the radar beam. However, although bat activity was significantly reduced during such trials, the radar had no significant effect on the abundance of insects captured by the traps.”

          “An even greater level of significance was however observed when foraging sites were exposed to a medium pulse length signal from a fixed antenna (bat counts and bat passes dropped by 38.6% and 30.8% respectively)”

          • mike_dyke

            Thanks for a great reply – I’m now more aware of the problems involved here.

            I don’t know enough about bats so… I know that birds are often scared off by statues of birds of prey (Put them on the tops of wind turbines?) but are bats scared of anything in the same way?

          • Not that I’m aware of. Maybe penguins? 😉

          • mike_dyke

            I suppose that’s why you never see penguins and bats in the same place 🙂

      • OneHundredbyFifty

        Looks like EPRI is doing some work on this

        Somebody should fund MIT Lincoln Laboratories to do work on this, they have a high concentration of good people that do anything and everything with radar. Lots of military but they also do civilian R&D.

  • Doug Cutler

    Good informative article. Is there a good credible citation for the 1:86,000 wind turbine bird death ratio? I’ve seen other charts for bird deaths from multiple sources but not this particular calculation. It would be handy info when debating inevitable “wind turbine as death machine” detractors.

    I’ve been thinking of forming an organization called HISS (Housecat Indoor Sequestration Society) and inviting those so apoplexed by wind turbine bird deaths to join or donate. Or not. Meantime, requested info cold be very useful.

    • Yes, the analysis for the 1:86,000 is on my blog with references, cited below.

      The brief breakdown is as follows:

      1. US continental bird populations vary from 10 billion to 20 billion annually between breeding, migration and wintering. 75% of birds don’t make it to breeding age and 50% die annually.

      2. The median of avian mortality from wind farms based on studies is 234,000 per a September 2013 peer-reviewed report.

      3. 20 billion divided by 234,000 is 86,000.

      Picking different numbers such as maximum avian mortality and minimum annual population will give you a different really, really big number, but that ratio is the most realistic in my opinion.

      • Doug Cutler

        Yes, best not to get too sentimental about life in the wild with Mother Nature herself taking by far biggest toll.

        So, the 1:86,000 is a ratio for bird death from turbine vs All causes man-made or natural.

        Do we have a ratio for turbine vs just other man-made sources like tall buildings, microwave tower, moving vehicle, etc., etc. and including outdoor house cats? Ferral cats might be considered borderline man-made vs natural but we could likely include them.

        • Per Sibley Guides — which align with other sources —, here are the anthropogenic cause numbers.

          – Lighted window impacts – 97 to 976 million
          – Predatory house cats – 500 million or more
          – High-tension wire impacts – up to 174 million or more
          – Pesticides – 72 million and possibly many more
          – Car impacts – 60 million

          Taking the bottom and top of the ranges, it’s about 900 million to two billion or so.

          That gives a ratio of 5% to 10% of all birds in the continental USA dying annually due to human causes. So the comparable numbers to the 1:86,000 are 1:20 or 1:10.

          Cats alone are 2.5% or 1:40, while lit windows are 1:200 to 1:20.

          Wind turbines suck up a lot of the attention on avian mortality, but they really aren’t a problem. It’s a red herring, or perhaps just a red-breasted robin.

          • Bob_Wallace

            Or an oil-soaked pelican…

          • CTO

            I do appreciate tall the thought Mike, but you’ve made a few internal errors. Your report (How significant is bird and bat mortality due to wind turbines?) states 100-200 billion birds worldwide but I don’t see the connection with this and 10-20 billion in the US. Nor do I, as an avian ecologist, believe that 50% of all birds die within 1 year and 75% make it to breeding. A chick that survives a week outside the nest never migrates through a wind-turbine zone and therefor is never exposed to the risk, therefor is not part of the “population” for which you are estimating mortality rates. I’m not intending to bash your numbers, but you use a lot of internal rationalization to justify your statements and some of those are on shaky foundations. And your comparison number just doesn’t pass the smell test, 10% of all birds in the US die due to human causes in each year? Our cities would be awash in bird carcasses if that were the case.

          • Bob_Wallace

            Being an avian ecologist, perhaps you could take a look at something I put together a few months back and see if you can spot errors.

            Highest estimates are that in 2012 there were 573,000 birds killed by wind turbines. (1) That number is an outlier which was published in March of this 2013 and was not based on actual kill counts but on “assumptions”. It’s as much as 17x higher than research papers based on actual counts. We’ll have to wait a while to see how the scientific community treats that paper.

            But let’s go with it. A bit over 1/2 million. Let’s err on the side that makes wind as bad as possible. Then let’s put it in perspective.

            Domestic cats in the United States kill up to 3.7 billion birds each year. (6,457x wind)


            Collisions with buildings kill 976 million birds each year. (1,703x wind)


            Collisions with vehicles kill 380 million birds each year. (663x wind)


            Collisions with communication towers kill 174 million each year. (304x wind)


            Poisoning kills 72 million bird each year. (126x wind)


            The Exxon Valdez spill killed almost a half million birds.


            Conclusion: Wind turbines are a tiny, tiny cause of bird death.

            But bird deaths aren’t a good thing regardless of the numbers. So why don’t we stick with coal and nuclear energy to save birds? Let’s check to see if that would work. Based on bird kills per gigawatt hour of electricity produced.

            Wind farms kill roughly 0.27 birds per GWh.

            Nuclear plants kill about 0.6 birds per GWh. (2.2x wind)

            Fossil-fueled power stations kill about 9.4 birds per GWh. (34.8x wind)


            OK, so now we know that wind farms are not one of our birds’ big problems. And we know that closing nuclear and coal plants and replacing them with wind farms would be better for the birds. Should we stop there?

            No, we can make wind farms even safer for birds.

            In 2009 there were 12.5 bird kills per MW installed wind capacity.

            In 2012 there were 9.5 bird kills per MW installed wind capacity.

            That’s a 24% decrease. A very major improvement in bird safety. And we aren’t done yet.


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