Leading Edge Erosion: When Precipitation Destroys Wind Turbine Blades

Erosion is all around us, from the meandering course of rivers and other waterways, to the gradual carving out of channels in even the toughest mountains, and the softening of features in statues. Yet generally we expect erosion from precipitation to be gradual and gentle, taking decades to make a noticeable difference. This of course takes into account gentle flows and the soft pitter-patter of rain on stone, not turbine blades passing through the air at many times the terminal velocity of rain drops of up to 9 m/s.

As wind turbines have increased in size and diameter of their blades, this has noticeably increased the speed of especially the blade tips. With more and more wind turbine blade tips now exceeding speeds of 100 m/s, this has also meant a significant increase in the impact of rain drops, hail and other particulates on the lifespan of these turbine blades. As comparison, 100 m/s is 360 km/h (224 mph), which is only slightly slower than the top speed of a Formula 1 car.

The effect of turbine blade leading edge erosion (LEE) not only decreases aerodynamic efficiency, but also invites premature failure. Over the past years, special coatings and leading edge tapes have been developed that act as sacrificial surfaces, but as wind turbines only keep getting larger, so does the effect of LEE. Beyond simply replacing LE tape every year on every turbine, what other options are there?

A Growing Problem

Examples of leading edge erosion in the field across a range of years in service. (Credit: 3M)
Examples of leading edge erosion in the field across a range of years in service. (Credit: 3M)

Although LEE is not a unique problem with wind turbine blades, they are in a rather unique position in that unlike propeller blades and turbine blades in industrial equipment or jet engines, they are exposed constantly to the elements. In addition, their sheer size is beyond that of these other blades, which complicates inspection and maintenance.

In a review by Keegan et al. (2013, PDF), a number of causes of LEE are identified. These can be broadly grouped into the following categories:

  1. Rain drops.
  2. Hail.
  3. Sea spray.
  4. Sand and dust.

Which of these a specific wind turbine is exposed to depends on the location where it is installed. For some off-shore wind turbines all four of these may be a factor, while for other only sand or rain may be relevant. Regardless, the result remains largely the same. With the impact of a rain drop or solid particulate, the leading edge of the blade will experience a transfer of kinetic energy that over time will weaken and erode its structure. In the case of a rain shower and a modern wind turbine, this involves constant strikes by 0.5 mm – 5 mm diameter droplets at around 100 m/s.

Rayleigh surface stress contour plot at leading edge coating system at various stages of contact force history (Credit: Verma et al., 2020)
Rayleigh surface stress contour plot at leading edge coating system at various stages of contact force history by a droplet. (Credit: Verma et al., 2020)

In a study by Verma et al. (2020) in Composite Structures, the force distribution of rain droplets for offshore wind turbine blades was examined. Using a range of modeling techniques, it was found that by reducing the blade tip speed from over 100 m/s to around 80 m/s, much of the impact damage can be avoided during heavy precipitation. As comparison, with a blade tip velocity of 140 m/s, the maximum impact force was found to be 181 Newton, whereas at 80 m/s this was reduced to below 70 N, making for an approximately 70% reduction.

As wind turbines keep growing in hub height and corresponding turbine blade length, such extreme blade tip velocities may become increasingly common, especially for offshore wind turbines which tend to be significantly larger than their onshore brethren. Reducing the blade velocity during heavy precipitation or storms with severe sea spray by partially feathering the blades, or employing the brake system, at least part of the LEE damage may be avoidable.

Unavoidable Maintenance

Calculated effects of varying levels of leading edge erosion on the Annual Energy Production of a 1.5MW wind turbine. (Credit: 3M)
Calculated effects of varying levels of leading edge erosion
on the Annual Energy Production of a 1.5MW wind turbine. (Credit: 3M)

In concrete terms, the effect of LEE is such that it can reduce the output of a wind turbine by a few percent after as little as a year, with even mild pitting affecting the efficiency of the turbine blades by disrupting the airflow over its surface. The general model for LEE as it pertains to turbine blades and propellers was created by G.S. Springer in 1976 in Erosion by Liquid Impact. This model uses the waterhammer principle, and is critically examined with improvements suggested by Hoksbergen et al. (2022) in Materials.

In a study by Law et al. (2020) the data from wind farms across the United Kingdom was analyzed. It was found that an average loss of output by each wind turbine per year of about 1.8% was to be expected, with the worst affected wind turbine experiencing losses of 4.9%.

Most interestingly about the study by Law et al. was the finding that the application of leading edge repair tape (leading edge protection, or LEP) to repair LEE damage to a turbine’s 3-year old blades resulted in an additional 1.29% drop in output. This shows just how important the shape of the turbine blades is in order to get the best possible performance, and exemplifies the issue with field repairs using LEP tape.

Although there’s an argument to be made that leaving the LEE to continue unchecked would lead to even worse performance over time, there should not be the expectation that applying tape to the leading edge of a damaged turbine blade will return it to its former glory. Major et al. (2020) also report a 2%-3% drop in Annual Energy Production (AEP) from the use of LEP tape.

A 2019 article in Renewable and Sustainable Energy Reviews by Herring et al. further expands on the complexity of turbine blade field maintenance. Unless such tape is properly applied, it may peel off, have wrinkles or air pockets. This article also addresses the option of applying a metal anti-erosion shield to the leading edge. This would provide good protection against erosion, but adds the complication of a hybrid composite and metal blade structure with different stiffness.

Finally, there is ongoing research (McGugan et al., 2020) on adding sensors to wind turbine blades in order to monitor vibrations and other parameters that can indicate damage to the blade, including LEE damage.

Tiny Droplets, Big Consequences

In the end, reducing LEE is a double win in terms of less blade maintenance required and higher efficiency, but the solution is by no means simple. Even small changes such as the thickness of LEP tape can matter when they’re scaled up to the size of a giant wind turbine blade, with significant financial implications from lower efficiency. As blade tip speed increases with ever larger wind turbine blades, so does the importance of developing better ways to protect the blade’s surface.

 

83 thoughts on “Leading Edge Erosion: When Precipitation Destroys Wind Turbine Blades

  1. Love to know how big that 1,2,10,10+ years blade is, as it seems from my reading to be that sort of age its can’t be even close to the giant monsters getting put up everywhere today. Are we at a stage now where the big blades are so big they are going to look like 10+ years in one, maybe two years? As from what I know the construction methods and materials haven’t really changed at all, they just got bigger.

  2. I wonder if they studied the effects of the blades chopping off bird wings. I mean thats got to cause a lot of of wear to the LE. Blade tip speed is 224 MPH. The blade in your lawnmower is limited to less than 200 MPH by the powers that be in the US. “As comparison, 100 m/s is 360 km/h (224 mph), which is only slightly slower than the top speed of a Formula 1 car.” Also another thing is insects. There are many insects with a weight greater than a rain drop so how does a locust swarm effect the LE.

    1. I don’t know about “chopping off bird wings”, but I do know they study how many of different types of birds are killed by each specific turbine. There are endangered species (birds and bats) for which this really matters.

    2. I know GE has studied all of this as I have a friend who works for them. Actual bird strikes on the blades is pretty rare, the problem is that when a bird passes behind the airfoils the pressure drops so much that their lungs fail.

      I’ve personally worked in a coal plant. You don’t see that many birds lying dead next to the plant, but there is a plume of death downwind from them that makes the impact on birds look like a tiny bump in the statistics.

  3. “Best possible performance” depends on your definition.

    It would be far better to optimize the wind turbines for lower wind speeds, not maximum energy production, because then they would be producing power more of the time. Since the tip speed ratio is usually fixed, that would also mean the particle impact is reduced and the turbines last for longer, which compensates for the loss in energy output.

    Modern turbines are optimized for generating the maximum amount in subsidies as quickly as possible before the subsidy term ends, which is paid on a per production basis (price guarantees, tax breaks), so they work poorly relative to the actual demand. They’re also typically dismantled and replaced before their technical EOL because building new turbines gets new subsidies and maintaining old turbines loses money, so nobody really cares whether they last beyond 12 years or so.

    1. For once I agree with you rather completely, as long as you combine building for practical lower wind speed operation with the ability to survive and ideally still work in high wind speeds. Which can be a tough challenge, so probably have 1:4 turbines that only really work well in high windspeed by design or something so the low speed optimised ones can be kept disabled and safer from harm in the high winds.

      It has annoyed me no end that turbines that have quite likely decades of life in them have just got dumped because its so easy to put up a bigger one in place of the old. If we want to replace them with more potent ones and not allow them to get put back up somewhere else nearby why not drop a few in the plains of Africa, sell them to the Aussie farmers in the middle of nowhere or something where they can still be useful – way better than just making them waste.

        1. It most likely does, when you are putting in full grid tied infrastructure. But as a lone water-hole in the desert all you need is the base to put it on really, how the output gets regulated for use likely already existed for the gas generator/backup battery type stuff these places need anyway.

          1. Yes, but again for those applications, you need an entirely different turbine that is designed to run consistently at low wind speeds, rather than pump the well dry once in a blue moon with megawatts of power.

          2. Not really Dude, the more offgrider mentality in these places is required and means you don’t care if any one source is putting out, as you have many. Usually all way overspec to your actual requirements too!

          3. If your turbine is making power on just one day in the average week, the limitation is how much batteries you have. Therefore it makes no sense to have a second hand megawatt-scale turbine on your ranch because utilizing it would require you to invest in more batteries, versus a smaller multi-blade turbine that turns more steadily all the time and requires little or no batteries to meet your actual needs.

            In an isolate off-grid case, it is even more paramount that the energy output is steady rather than great, because storage is ultra expensive and you have no transmission for backup whatsoever.

          4. The idea of “overspeccing” in terms of wind power here is like buying a drag racer for running your groceries, because what you trade in favor of greater energy output is lower coefficient of production: greater intermittency, less time spent at the nominal output, which is more difficult to deal with.

          5. I could sort of agree, except the EOL’d smaller commercial windturbines do work in a rather huge range of windspeeds, its not producing its optimal but it is working more than enough for the orders of magnitude lower demand its expected to see in this set up. So as long as you set it up somewhere that is even remotely windy – which in this context is damn nearly everywhere not stupidly sheltered its fine.

            Its not a dragster for the groceries, at worst with that analogy its the road legal sports car for the job – massive overkill potential, but it will just do the job most of the time without fuss…

          6. Oh, don’t forget that a wind turbine consumes around 5-8% of its own nominal production to operate itself.

            There’s hydraulic pumps and heaters, coolers, fans, computers, etc. that run all the time, and when the turbine is not being turned over by the wind, there’s a small motor that keeps turning the blades like a clockwork to prevent it from pitting the bearings. Magnetizing the induction generator itself also takes significant amount of power, so you really don’t want a big turbine for a small load, because the cost to power the turbine can easily be greater. We’re talking tens of kilowatts, up to hundreds for the largest units.

            When you get those dead cold calm days in January and February with a high pressure zone sitting stuck over the country, wind turbines actually turn into net consumers of power.

    2. “It would be far better to optimize the wind turbines for lower wind speeds, not maximum energy production, because then they would be producing power more of the time.”

      That’s an interesting tradeoff.

      The trick with wind power is that the power goes as the cube of the windspeed (~volume of air / sec) and the square of blade size (swept area). So you want to run big windmills, and you _really_ want to run them when it’s blowing hard.

      I went looking for numbers — best I can see, wind folks model windspeeds as a Weibull distribution, which falls off like a square root at the tails. Multiply by windspeed to the third, and you get the bulk of wind power produced on the least frequent, very windy days. 50% of power on the 15% most windy days? Something like that. If you can do the math, please!

      But the point is that most of wind power generation happens when it’s really windy. This does put strain on storage and transmission, but you’re fighting against _huge_ efficiencies on the production side.

      Of course, if the wind is blowing and there’s no turbine intercepting it, that’s energy lost. So it might also make sense to think about low-speed turbines too. But I think the dollars / kWh are stacked against it.

      1. Cost of the windmills themselves would probably be against it, as to really work low speed probably makes the internals more complex, reintroduces a gearbox perhaps. But cost of the overall system probably not even close to as high – as it stands technologies available now make storage vastly more costly than generation and the very very peaky unreliable wind turbines likely require orders of magnitude more storage if you wish to rely on them.

        Or likely you end up putting even more turbines up compared to what you would with lower windspeed capable ones in hopes they are distributed enough to get some catching useable wind anyway – at which point the cost of the windmill is probably rather similar in price for average/minimum system output power, but not of course in peak power. Though putting up lots of the current standard turbine is another route that makes enough sense to me, at least for perpetually windy coastline filled islands like the UK where good enough wind to run windmills well is a near certainty somewhere and that can easily consume or transfer the excess spikes when more are working. It just doesn’t work out so well in places that tend to gentle breeze over vast plain most of the year, where the weather is more likely to be becalm all of them at once.

        1. It seems to me that the cost of running a turbine depends on its run time.
          So you colocate a number of turbines optimised for different wind speed, and stall/brake the ones that are not being used efficiently or when supply exceeds demand or the capacity of the transmission lines.

          When they are stalled, they don’t wear out.

          1. When they’re stalled, they’re not making any money either.

            The present LCOE of wind power is competitive with traditional power with the huge megawatt-scale units that only really produce anything when it’s blowing harder than 5-6 m/s, so if you need to build two or three turbines for the effect of one, it raises the cost of wind power back into the “doesn’t make sense and nobody will buy it” category.

          2. The thing with that Dude is current fossil fuels still get massive subsidies to make them ‘make sense’, but the world is having to move away from that model – Now rather faster than ever. With things like this it is rather more if there is a public acceptance/desire then it will ‘make sense’ to buy into, as the levers on the economy are moved around to shift the whole system to that way of working.

          3. > current fossil fuels still get massive subsidies to make them ‘make sense’,

            No they don’t.

            Some arguments like that are actually based on muddled notions of what and why “fossil subsidies” are, where actually most such subsidies are consumer subsidies (price reductions) paid for domestic political reasons. Basically in part to efforts to keep the people from revolting and throwing down their autocratic governments. The top five spenders are Iran, China, India, Saudi-Arabia and Russia.

          4. See:

            https://www.iea.org/data-and-statistics/charts/value-of-fossil-fuel-subsidies-by-fuel-in-the-top-25-countries-2020

            In the western world, fossil fuels are rather a source of tax revenue rather than a target for subsidies. They don’t pay you back for filling up your gas tank – they take about 2/3rds of the price in taxes in the EU, and electricity producers have to pay for CO2 emission quotas… all to pay for the “externalities” of production without actually doing anything about the issue.

          5. It is vastly more complex than that Dude, for instance nearly all oil and gas exploration isn’t fully company funded, the refinery and extraction rigs have often been given a substantial public funded boost, the transport infrastructure to bring the coal to the power station likewise – there are subsidies of one sort or another in a great many areas around fossil fuels, with vastly different pictures globally as to how and where. But they and their legacy benifits do exist, even in the EU!

            And being a global market subsidies in nation x,y,z can often be seen having a rather direct impact on locations at the other end of the alphabet.

          6. On the whole, the US puts out about $20 billion in direct subsidies to the fossil fuel industry each year, but collects a total of about $138 billion in taxes in return. It’s a similar story in the EU-27 which spend about $55 billion a year on fossil fuels, but collect about $300 billion in various environmental taxes in return.

            If you give a dollar and take seven, is that really subsidizing?

          7. The point is you don’t give and take like that all the time, or even necessarily often, and being a global economy if the foreigner’s choose subsidies for their industries you can also benefit.

            And when you go and throw them a few billion in one year for a specific project that upsets only one years ratio, but as the benifits of that investment last in some cases decades the tax:subsidies right now isn’t really directly relevant – it needs a much wider viewpoint including all the historic subsidies.

          8. > it needs a much wider viewpoint including all the historic subsidies.

            It’s much simpler than that. The history doesn’t matter, the type of subsidy does. Fossil fuel subsidies tend to be investments and loans into something that then produces the value back in multiples – it’s about removing barriers and thresholds between supply and demand – whereas renewable subsidies are just buying the resulting energy to generate artificial demand on the consumer side, to prop up an industry that isn’t cost competitive and will not be made so by the subsidies.

          9. In a sense, fossil fuel subsidies are like paying a barkeeper his barrel, so he can buy and sell beer, so you can tax his customers for the money back from every pint they drink.

            Whereas renewable subsidies are like paying the barkeeper half the price of every pint he sells, because the beer is so bad that the customers wouldn’t pay the full price if you didn’t.

          10. How subsidies are implemented I can agree matters, but you can make a massive mess in how you you implement it with anything – you can subsidise the analogous barrel in renewables as well if you so desire, and likewise many a subsidy exists tied to fossil fuels nobody actually wants to pay for at the going rate…

            But no matter how you do it you MUST consider the legacy of past subsidies and take a longer view to be remotely fair. Massive public cash injections even decades ago to create the current state of affairs are still meaningful now, and in theory anyway the same can be true of renewables massive injection now and 50 years later the whole system is well established and normally doesn’t need help (though often will still get it as its notoriously hard to actually make ‘cuts’).

          11. >you can subsidise the analogous barrel in renewables as well if you so desire

            You can, but the renewables won’t operate that way. Without the price guarantees, wind turbines would be making a loss anyways trying to sell against a glut of their own making. You may subsidize their construction, the land, the financing etc. but you can’t make them run profitably when the supply doesn’t meet the demand. That is why they are subsidized per MWh sold – to force the point – which is even more the case for solar power which receives several times the subsidies per unit of energy.

            >But no matter how you do it you MUST consider the legacy of past subsidies and take a longer view to be remotely fair.

            Being fair is a pointless sentiment, when the real criteria is whether the subsidies actually enable the technology to work for the society. This is not Special Olympics where you get a prize for participating even if you can’t actually run the 100 yards.

          12. That said, there are some places that are consistently windy, like around the coast of Scotland or the seas around northern Germany and Denmark, where the coefficient of production rises to 0.4 – 0.5 and it’s these projects that have placed bids to sell without subsidies because they have a greater probability to sell when the power is actually needed. Though then there are other incentives, like the German right-of-way law which forces other producers to shut down when the wind is blowing, which is kinda the same thing.

            Meanwhile, in the past 20 years loads of on-shore turbines were built on locations that do not produce well with an average CoP around 0.2 exactly because they were subsidized. The pressure was to build them where existing roads and power lines, and low land prices enabled cheaper construction. Since the profits were guaranteed, it did not matter that the output was sporadic and ill-timed – they just filled the landscape with turbines and took the money.

        2. > as to really work low speed probably makes the internals more complex

          Not really. It just requires adding more blades to the turbine. The peak efficiency of a three blade turbine is around a tip speed ratio of 7-8 whereas a four bladed turbine runs best at a ratio of 4-5, which means four blades turns equally fast at approximately half the wind speed.

        3. >Being fair is a pointless sentiment, when the real criteria is whether the subsidies actually enable the technology to work for the society.

          I do agree it has to work for society BUT being fair is entirely so you are judging comparable information to have some idea if your current investments have any merit – you invest 600B over the last few year on a super factory industrial estate that needs no major further investment costs this year that 600B is still very much part of this year, and next year, and the year after that (etc) economic output – so comparing public investment in it this year to the public investment in the new project considering only the funding this year is entirely daft – you must factor in the timescales the investment works over – which obviously for the past project is looking up the data and the new one involves some projection, but in both cases your projected investment to return must be considered – you can’t judge the value just on the long established and still deeply in debt to the public purse project is cheaper in this months budget alone!

          >…were built on locations that do not produce well with an average CoP around 0.2 exactly because they were subsidized. The pressure was to build them ….

          Yes that is perhaps a problem – but then again perhaps not – all down to how big a picture and how much investment you put in – lots of turbine spread over lower yield site distributes all the eggs wide enough to help compensate for weather variability, and being able to do so very cheaply leveraging lots of existing infrastructure makes the investment in the future of the system potentially a really really good investment. It is so much cheaper than building in all the more isolated but ‘best’ spots for the technology AND a wider net that means more reliable production overall – you likely build many many times more windmills BUT it was a heck of alot cheaper to build them there so the overall cost may even still be lower AND they are not all clustered in those relative small geographic locations where one small weather system might take out large percentages of the output power.

      2. >This does put strain on storage and transmission

        And how. We’re literally talking zero power prices today, and threatening rolling blackouts tomorrow because wind power is basically running full on and full off. I’m not joking, that’s literally what we’re seeing where I’m at, since the whole power system is strained because of you know who.

        It puts a very hard cap on the scalability of wind power because it has to be curtailed beyond what we already have to not break the grid, which means most of the “hugely efficient” turbines are not allowed to turn when they would be making the most energy, which makes them not efficient and not cheap – doubly so because we have to pay them the “lost revenue” for what they would have made if they were not curtailed as per policy.

      1. It is way more than just blades being variable pitch to really being optimal for any given wind speed, variable pitch is a useful control to allow better function in some varied speeds. However its not the same as having the blade profiles, blade count, desired rotation speed for most efficiency at the generator all designed to match for the specific wind speeds targeted.

        1. It actually is if you are limited by the generator. If they start generating at 2.5m/s and the generator is maxed out at 8m/s, what do you hope to change at 12, 15 or 20m/s? They are optimized for low speeds and pitched to prevent damage to components at moderate wind speeds and above.

          1. That there is exactly the point the generator maxes out at 8m/s in your example, that is pretty high winds, for some places about as fast as they ever get, and it probably doesn’t really get close to performing at its best until the winds are basically at that speed. It is a pretty good speed target for much of the UK, as the average windspeeds are often in that sort of ballpark, but even here 4m/s is probably a better target for the reliable “low wind” operation…

            So to be really optimal as a ‘low wind’ spec as Dude suggests it really should be hitting optimal production well under that 8m/s or at least its output curve to windspeed should peak significantly much much earlier than it does, and probably be functional even down at something like 1m/s. Which means you need some of lower friction bearings, more blades, lower speed geometry optimized blade, larger blades, and a generator that is hitting its most efficient operation window at the lower rotational speeds the lower windspeed (likely) produces (So a gearbox as well perhaps).

            But going that far to low speed optimization you end having to lock the blades at their poorest wind catching profile and the rotation of the generator as a whole when the wind does pick up to prevent damage, and likely need to make the towers substantially stronger to deal with the much larger wind loading potential created so it survives that 1:100 year storm (or whatever the existing required safety margin is).

          2. > what do you hope to change at 12, 15 or 20m/s?

            The turbine cannot rotate arbitrarily fast, because of the mechanism, and also because the wing tips would pass the sound barrier, so a turbine that is optimized to reach its nominal speed and power rating at 3-4 m/s will actually approach zero efficiency at 10 m/s as the tip speed ratio grows with the rising wind speed. Even higher wind speeds require you to stop the turbine to prevent harm.

            It’s basically an impedance mismatch problem. When the turbine goes out of its optimum range, air starts to pack up front into a high pressure zone that pushes the wind around the turbine rather than through it.

    1. If only they wold go nuclear. The damn windmills are a blight on all the amazing landscape where I live. And mainly in areas where the hydroelectric produces a surplus but is not considered in the same class of renewable.

    2. Having been to Mumbai, all I can say is, dump them on a beach in India or Bangladesh and within a week they’ll come up with at least 1000 uses for the old blades. Even the “non” recyclable ones. Skies, phone cases, bike fenders and about a million other things.

  4. It’s the weirdest thing to me that we haven’t figured out how to create a more graceful wear behavior. With the monthly article on fancy self-healing polymers and abrasion-resistant composite material formulations, one would think such approaches would be profitable, though it might also point towards a lack of actual solutions.
    Imagine something nature-inspired, like aerodynamic surfaces that can undergo a controlled exfoliation, exposing a smooth and pristine surface every 2-3 years… and then consider what duct tape feels like after that time outdoors in the sun :D

    1. If we could get them to regrow surfaces, that would rock, but of course it’s going to be hard to get any living tissue to survive those conditions.
      I’d be interested in boundary layer control. Jet turbine blades can’t tolerate the heat in the hot section of modern jet engines, so they shoot out bleed air that provides a tiny insulating layer between the hot erosive stream coming out of the combustors and the turbine face, and it’s going a lot more than 300 km/h. (But it also has a lot less kinetic energy so it’s easier to deflect than raindrops or bugs or particularly sand.)

    2. those are usually research. Getting something to work on a research scale is one thing – and I really don’t want to take away any of you researcher guys credits, kudos to you! Getting that same thing on an industrial scale is something else entirely. You can get a PhD with one working sample out of thousand, for industrial production you probably can’t get away with that

      1. You overestimate how hard it is to get a PhD.

        Just don’t ‘pump and dump’ one of the committee member’s daughters. That’s a bad plan. It’s just campus politics (‘so brutal because the stakes are so low’). Even worse in the humanities, stakes are even lower.

        We’re up to our noses in underemployed Drs. Count the physics PhDs writing beancounting code…you can’t. The number is increasing faster than you can count.

        Dude nailed the real issue uptread. ‘Perverse economic incentives’ would be a good porn movie title.

  5. An easy way to fix this is to eliminate the subsidies. Once the subsidies are gone, there won’t be any new windmill installation. Problem solved and money saved. Plow that cash into nukes and you’ve got another big win.

      1. Yeah plow that cash into nukes, exactly. It’s subsidized all the way down baby. Might as well take the absolutely worthless corn out of our diet and gasoline, bust down the absolute scam windmills, throw those people in jail, and then put it into something that actually is a viable solution. Did I mention to throw the people in charge of this in jail?

    1. The problem when you start on “subsidies” is that you eventually look at all of human activity.

      The military? The largest recipient of gov’t subsidies. Doesn’t generate any revenue. That’s out.
      Education system? “Subsidies”.
      Interstate highway system? Entirely subsidized.
      Medicaid / medicare? You know it!
      The cops, the fire department? They don’t charge for their services directly. Buh bye.
      Farming? Don’t say the “s” word if you want to keep eating.
      Solar? Nuclear? Wind? Coal? Oil? Yup. All of them. Pick your poison.

      The question is not whether or not something is paid for with public funds, but rather _what_ to pay for with public funds. And a first cut at an answer there is “the things that would benefit society, but aren’t profitable when provided by the free market”. (Because otherwise, why would you do it?)

      You are now free to make the case for or against spending the public money on wind vs. nuclear vs. oil. Backed up with facts. Go.

      1. The difference is that some things that are subsidized produce a net return of value, whereas others don’t.

        Another thing is that there are different kinds of subsidies. A loan guarantee is a subsidy that is worth some amount of money because it saves on financing costs, but it is not actually any money paid by the government unless the company defaults. The subsidies received by nuclear power for example are these kind of subsidies, whereas wind power and renewable energy subsidies are just literally the government buying energy to hide the above-market-rate cost from the consumers.

        1. Of course the rationale for renewable energy subsidies is that the costs will go down when the industry matures, which kinda-sorta happens, but not really.

          The ill effect is twofold. Subsidies enable the producers to not deal with or get punished by the external costs, such as supply not meeting demand, so they don’t have to solve that issue. It’s somebody else’s problem. Then, producers that put their money on expansion rather than development get greater profits faster and steal the market, so the subsidies slow down the development of the technology.

          The real development happens when the subsidies are removed, because the industry finds itself in a position where nobody is willing to pay for ill-timed power, and they haven’t paid any for R&D to solve that issue or deal with it. However, the easier solution to this situation is to simply keep lobbying for more subsidies, which is why it’s a political gridlock. You already gave the industry hundreds of billions to grow into a big baby that will keep demanding more.

      2. > And a first cut at an answer there is “the things that would benefit society, but aren’t profitable when provided by the free market”. (Because otherwise, why would you do it?)

        The correct version is, something that would be profitable but won’t be provided by the free market at least initially because nobody wants to take the risk. Once it starts, you should take your hands off and let it run.

        If it’s a thing that cannot be provided profitably by the free market, it cannot be provided profitably by the state subsidizing it either. A subsidy means that something is still provided by the free market BUT the government is paying for it. The subsidies simply distort the market and remove the competition and incentives that would put the prices down in the long term.

  6. It is odd but my brain instantly thinks about shark skin or cats tongue or cheetahs tongue. That instead of a single sharp blade like edge that the structure might fare better under harsh conditions if composed of millions/billion/trillions of microscopic teeth. I have no idea which direction they should be even pointing.

    And I have absolutely no idea at all if it would perform better or worse, but it is definitely the first thought that entered my head on hearing about Leading Edge Erosion.

  7. Now when i see a windmill, I see an environmental timebomb whirling away disseminating its fibreglass dust, chopping up creatures and causing noise pollution. Nevermind the synthetic composite nightmare of recycling.
    No, this is not hay fever, its asbestos class particulates.

  8. Well this comments section certainly bought out all the well-informed and rational folks and their aluminium foil deflector beanies.

    Really wish HaD would bring in an upvote/downvote system for comments so the dross can be allowed to fall to the bottom rather than just whoever posts first gets to the top.

  9. Reduce turbine blades diameter by half => reduce speed by half and wear (E=m*v^2/2) by 4 times. 4 smaller turbines should also be far simpler to install and maintain and you get the same power output and more resiliency.

    1. You also reduce output significantly when halving the turbine diameter. To reach the same output as a large one you end up building 2 or 3 half pints. A more expensive solution for sure.

      1. Power output is related to swept area, and wind speed. Turbine tip speed is not in that formula.

        To clarify, I said 4 wind turbines with half of diameter would be needed to replace 1 big one.

        1. Turbine tip speed is related to the wind speed by the tip speed ratio. If you make the same kind of turbine turn slower, you increase the tip speed ratio beyond its optimum point and the turbine becomes less efficient.

          The smaller turbine has to turn faster so the tip speed is equal to the larger turbine in order to generate power properly. Otherwise your reduction of one large turbine to four smaller ones will not produce the same power, but less.

          1. Or decrease? Was it wind-to-tip or tip-to-wind ratio?

            In either case, to keep the comparison apples to apples, both the large and the small turbine have to move their wings at the same speed relative to the wind to be equally efficient.

  10. Testing my flying propellor launcher toy, All of them blades are missing the circular rim part that can be made of cheap plastic, visit to a toy store will confirm that the rim makes all the difference. Just cut it off then try to pull the string again, it all breaks apart . seems like the circular shape add much needed stability and strength, without much weight .

      1. A turbine turning at one fixed speed is most efficient for winds coming it an one fixed speed. If the wind speed varies a lot – if the wind is gusty – the turbine efficiency goes down a lot.

        If the turbine had less inertia, it would speed up and slow down with the wind, capturing the energy better. Modern turbines using power inverters can do this, while older grid synchronized direct generator turbines couldn’t.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.