Study: Wind farms offer diminishing returns as they grow more widespread

As wind-turbine farms expand, research shows they could offer diminishing returns



LAWRENCE — Renewable wind energy is experiencing a boom, with more wind turbines popping up across landscapes in the U.S. and abroad. Indeed, wind energy accounted for 3.3 percent of electricity generation in the United States in 2011, according to the U.S. Energy Information Administration. Globally, that number was 2.9 percent for the same year.

But as wind turbines proliferate, researchers at the University of Kansas are looking at how these forests of turbines affect the wind itself. What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?

Atmospheric science professors Nate Brunsell and David Mechem in KU’s Department of Geography are co-authors of a new study just published in the Proceedings of the National Academy of Sciences by an international research group that evaluated the effects of large wind farms on atmospheric flow and its implications for how much renewable energy the turbines can generate.

“Wind turbines generate electricity by removing energy from the wind, so a larger number of wind turbines should result in a slowdown of the winds in the lower atmosphere,” Mechem said.

The researchers quantified this phenomenon in numerical simulations by applying a sophisticated model normally used for weather forecasting to one of the windiest regions of the United States.

The team found that a slowdown effect triggered by wind turbines is substantial for large wind farms and results in proportionally less renewable energy generated for each turbine versus the energy that would be generated from an isolated wind turbine.

While the researchers stress that no current or planned wind farm approaches the size or concentration that would cause the slowdown effect, their results suggest the phenomenon tied to large wind farms needs to be accounted for in future planning of wind energy.

“When just a few wind turbines are installed, each additional turbine results in a similar increase in electricity generated, as you might expect,” Brunsell said.

However, when a substantial number of turbines are installed over a small area, the amount of electricity generated is no longer governed by simple multiplication, according to the researchers.

“Instead, because the turbines extract energy from the wind, additional turbines will each generate less and less electricity,” Mechem said.

The team’s simulations estimate this slowdown effect results in a practical upper limit of 1 megawatt per square kilometer that can be generated — far less than previous estimates not accounting for the effect. Current wind farms are operating well below this generation limit, but the authors found that this slowdown effect needs to be accounted for, particularly when comparing different sources of renewable energy.

The study was published online in the scientific journal Proceedings of the National Academy of Sciences on Aug. 24.


182 thoughts on “Study: Wind farms offer diminishing returns as they grow more widespread

  1. Should be pretty easy to get peak instantaneous production values, and area in square km. from an existing windfarm, to support or falsify their simulation.

    • Once again, we’d be looking at a highly variable signal, trying to tease out a small effect. We’d need a differential study: measure downwind output with the upwind turbines idling, then again, pulling full power upwind at the same windspeed.
      But it wouldn’t be worth the effort. “…[T]he researchers stress that no current or planned wind farm approaches the size or concentration that would cause the slowdown effect…” The whole study is based on models and the effect is so small, nothing bad will happen unless we add a lot more windfarms, by which time something really bad will have already happened–the pointless wasting of billions of dollars to punish CO2 after a kangaroo trial.

    • How is this slow down going to affect local weather patterns and climate? There was a paper published a wee while ago that purported to show the lee of a wind farm suffered climatic warming.
      A few poor Indian farmers a number of years ago blamed a wind farm for their crop failures, but were laughed out of court. Seems there is mounting evidence taking energy out of the wind has an effect.

    • Not really necessary. This is a known problem. Before a wind plant is built, they run detailed wind models to determine optimum spacing and locations of turbines – including optimal spacing to minimize “shadowing.”
      The bigger issue, and what I was hoping would be addressed when I saw the title, is that increasing wind on a power system has decreasing value to the power system – both economically and from a CO2 perspective.
      Backing up wind plants requires that gas and coal plants operate at less than their maximum output. As the output of a gas or coal plant decreases, so does their efficiency. The first wind plant in a system may save 1 ton CO2/MWh and reduce fuel consumption by $50/MWh. As the amount of wind on the system increases, these value trends towards zero. It is a difficult question to analyze because every point on the power system is different. In an area with lots of nuclear energy (like France), the first wind plant is economically worthless and doesn’t reduce CO2 at all. In Hawaii, where most generation was traditionally from diesel fired internal combustion engines, wind is much more valuable.

  2. I wonder if their harvesting of winged wildlife follows the same pattern?
    Do the birds and bats get an opportunity to learn to avoid these killing machines?
    Or does the initial max kill thin the local populations down to a point of diminishing butchery?
    Notice all the emotive words, just trying out my inner Eco-Nasty.

    • Natural selection at work. The survivors will become so good at avoiding turbines we won’t see them any more. They’ll be hiding in the deep canyons where we can’t count them, but models will show us where they are, and that they’re doing just fine.

    • More dead birds & bats = more bugs & small vermin = more crop loss & diseases spread, requiring more insecticides & poisons to combat, or else a hike in food and medical cost.

    • One needs to take mortality rates with a large grain of salt. I believe several are model based and we know how well that works.
      My utility operates the second largest amount of wind generation in the nation. In ten years the number of eagle deaths stands at 4. Four dead birds in just over a decade. As a comparison, we average 10 – 12 eagle kills a year from our high voltage lines. I believe the number of eagles killed in the state by vehicles (hit while dining on road kill carcases) is even higher.
      The point being, if you are going to play the dead bird card for being critical of wind generation, make sure you know what you are talking about.

      • Where is your utility located?
        The Great Falls Tribune reported on November 8, 2013 that only two raptors were killed since the Montana Rim Rock Wind Facility went operational in October 2012, which is “‘an extraordinary number’ compared to higher figures documented at 20 wind farms in similar raptor habitat in the Pacific Northwest,” according to Greg Copeland, owner of San Francisco-based NaturEner USA. NaturEner USA runs an avian alert system. No link. I am quoting directly from the printed version.

      • Right next door in WA.
        Personally, I am going to believe our avian compliance guy (I was talking to him during storm duty this weekend) efore some guy in SF.

  3. Ya know, I have to wonder if some engineer working for these wind companies did a back of envelope computation and walked up to their (including both sexes here) boss and told them about this – which from an engineering point of view is obvious.
    If so it would be akin to the NASA engineer who said – “don’t launch it!”
    It would be interesting to see what these companies are telling our political leaders.

    • Poor analogy. Windfarm constructors are well aware that you space turbines out sufficiently to minimize locating turbines in the ‘windshadows’ of others. And, again, the “researchers” admit that there’s no effect until we have jillions more turbines installed than we do now. God forbid. The study is based on computer models counting angels riding unicorns on the heads of imaginary pins.

      • Jorge
        Windfarm constructors are well aware that you space turbines out sufficiently to minimize locating turbines in the ‘windshadows’ of others.
        Not really. The designers are also constrained by the size of their allotment (fishermen and sailors also want to use the sea), and the cost of joining up all these windelecs (turbines). So the whole thing becomes a compromise, where the downwind windelecs do indeed get stuck in the windshadow of the upwind windelec. I have not seen a table of energy reductions, as you go back through the array, but there must be a reduction.

      • Ralf, they only have to make sure every other mill turns the other way around. Will compensate for the loss.
        { /sarc }

  4. Wait til the day of irony comes when it is determined that wind turbine construction is directly tied to increasing ground temperatures – the supposed solution is the problem. The taxpayer gets screwed again when they pay to have the ugly monstrosities torn down. 🙂

    • I’m not sure what is meant by “it is determined that wind turbine construction is directly tied to increasing ground temperatures.
      Restoring the land to its original condition and surface elevations is included in the contracting and permitting process.

      • @ jorge ; And you really, like really think THAT is ever going to happen? By that time most of those companies that signed those deals will be (if they aren’t already) be bankrupt and long gone. (while their first owners have raped the tax payers blind!).

      • I guess there always a “superfund” for cleanup of things the government should not have interfered with in the first place.

      • “Restoring the land to its original condition and surface elevations is included in the contracting and permitting process.”
        Jorgek……… This is totally false, there are no decommissioning monies set aside in contracts unless the township/or county of a given state puts it in their Wind Ordinance. Wind companies will not include those cost unless they are forced to, and or, will profit heavily for doing so. Remember though, should that company fail, you got nadda.
        Also, you will never restore the land to it’s original condition. They even “take” the dirt they dig out for the humungous concrete base and do as they please with it.
        *raises hand as one who has seen and read a contract* ( tee-nee tiny gag clause included)

    • The area actually occupied by the turbine’s base and the access road are not large. The remainder of the area can be farmed or as before. There will be little or no effect on ground temperatures.

      • Only by persons who are deaf. I understand low frequency noise pollution is driving people nuts.

      • Oh Yes they are! They contain huge amount of concrete as well. The base areas are easily the size of a football field for each turbine, and to a depth of 30ft I think.

      • Chris – effect on ground temperatures –
        hey analysed satellite data from 2003 to 2011 over a region in west-central Texas where four of the world’s largest wind farms are home to more than 2,350 turbines.
        Most were built between 2005 and 2008, allowing the researchers to assess the difference between a scenario with the smallest impact on the local climate and a scenario with the greatest.
        Their findings are published today in the journal Nature Climate Change.
        “Our results show a significant warming trend of up to 0.72 degree per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions,” wrote lead author Liming Zhou, a Research Associate Professor from the Department of Atmospheric and Environmental Sciences at University at Albany. “We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind turbines.”

        Forget about the diminishing returns for an individual farm, what about all the early farms select the best wind areas and the latter get progressively worse locations.
        Read more at:

      • Chris4692, when you break it down, each turbines takes approximately 3 acres, one for the turbine and 2 for the road leading to the turbine. There might be no effect on ground temperature, but there is a profound effect on the surrounding land for the worms. They don’t like vibrations.

      • old construction worker, actually being deaf does not matter, LFN, low frequency noise travels into and through the body.

      • EJ: at 2 acres for an access road, 30 feet wide (a generous width) that’s 2,904 feet long. In that length there will be more than one tower accessed, if you need that length. Around here there are few places that are that far from an existing road. You are likely overgeneralizing.

    • The good folks at Iowa State University have been researching microclimates in the vicinity of wind turbines. link Downwind of a turbine the temperature seems to be a bit cooler during the day and a bit warmer at night. The researchers are aggies so they are deeply concerned with how the wind turbines will affect corn yields.

    • Yes the shear we not be insignificant.
      Will they heat or cool the planet? Those models with their stunning predictive capability will easily come to a conclusion.
      The frictional shear of tropical islands allows thunderstorms to form this process could enhance this. Elevating precipitation and cooling the tropics.
      We should rip all existing wind farms out from the temperate regions and install them in the Tropics, build nuclear power stations and power the fans to slow the wind to enhance the escape of energy in the convergent regions due to massively enhanced thunderstorms.
      sounds like win win to me.

  5. Serious question (please have mercy for I am a complete layman)
    Why is it news at all that a device which gets energy from the wind would in turn result is weaker wind? Isn’t that necessarily true? Isn’t this just another example of a model run, which assumes the laws of physics as we know it, confirming those laws? It’s like saying, “gee these hydro dams are great but it turns out it might actually change the environment around the dam a little bit.”
    I’m also really curious if anybody has studied the effects of turbines on the ecosystem. Obviously we already know they are really good at chopping up birds (yet another easily foreseeable effect) but what about stuff like pollination?

    • I’m afraid the whole wind and solar movement is in denial of the unintended ecological consequences. I get a pat answer of “Oh, they just claim that they kill things because they don’t like them. The government wouldn’t be helping finance something dangerous!” when I try to educate green believers.

  6. This effect is surely trivial. OK, it’s probably real but there are much much larger problems to worry about – there’s the need for backup generation, inefficiency, low energy intensity, visual pollution, noise pollution, grid stress, and lots more. Even bird and bat deaths need to be acknowledged and treated on a par with other industries. It’s time governments woke up to the simple fact that subsidising wind farms is economically destructive and environmentally destructive.

    • @ Mike Jonas US wind subsidies (wind farms) ended in 2014. Even then the Tax credit was only 2.3 cents per Kwh, meaning true subsidy of about .7 cents per Kwh — yup less than a penny.
      Consider that the fuel and Construction of Nuclear Plants has been subsidized for decades and your post seems misplaced.

      • Consider that the fuel and Construction of Nuclear Plants has been subsidized for decades and your post seems misplaced.

        Those are market driven, commercially viable solutions that provide needed, cheap, efficient and reliable energy. Wind and solar are none of those. They are politically manufactured frauds that produce an inferior and more expensive product.

    • See above regarding mortality rates. It is likely a mistake to take the large numbers being mentioned as accurate. You want actual data from facilities, not research studies, many of which rely on modeling.

  7. If we just disregard other considerations, the image at the top of this post looks utterly revolting. At least other (saner) energy mass-production plant types have comparatively tiny structural footprints. Even Hydro produces lovely lakes, birds, fish and flood mitigation, and wets the land.
    Not wind though, it’s just plain butt ugly, it destroys the beauty of the land. You’d have to be raving mad to think that eye-sore was a good idea.

    • That photo looks like the Smoky Hills Wind Farm out in central Kansas. It is butt-ugly and even worse, you can see it for almost 30 miles before you get to it, and it runs almost 10 miles along the interstate.
      One comment about the energy depletion across the wind farm–the wind in Kansas usually blows from the south and these turbines are stretched out on a long east west line–that is, the north-south depth of the field is fairly narrow. Kansas means “people of the south wind”.

  8. There is something else that needs thinking about. “Wind turbines generate electricity by removing energy from the wind, so a larger number of wind turbines should result in a slowdown of the winds in the lower atmosphere,” Mechem said.”
    Slowdown of the wind. So do enough wind turbines change the weather? Over time? Are you creating a desert one hundred, two hundred miles away by redirecting wind flow? Slowing rain carrying wind?
    How much of our warmest months ever have been caused by these wind sucking,, no life sucking Monstrosities? Oh well you get my point.
    michael 🙂

    • Trees do the same thing, the energy is expended in moving leaves and branches (which actually harbor birds).
      May need to cut down some of those recently planted trees to compensate for a loss of wind energy. :-p

    • Exactly what I was thinking. Perhaps the droughts in California are the result of wind farms sucking all the energy out of the wind and preventing moisture from being carried inland from the sea.

  9. Aside from deminishing returns in a particular favourable location, the most favourable sites are rapidly utilized. Other sites yield less energy or have higher costs…..think peak wind.

  10. Interestingly, the photo accompanying this article is of the Shepherd’s Flat “wind farm” in Oregon. As most readers know, wind generators will never produce enough electricity to pay for themselves without government subsidies and in Oregon, each separate facility (wind farm) qualifies for a $10 million subsidy. Shepherd’s Flat operators are currently under scrutiny for subdividing the large, contiguous wind farm into thirds and claiming that it is three separate facilities in order to qualify for $30 Million in subsidies. The three claimed separate facilities are adjacent, share the same interconnection bus and single output to the grid, sell their output to the same user, were financed by the same gov’t loan guarantee, built with the same purchase orders, by the same general manager, etc.
    Such shenanigans in the wind power industry are widespread, as the projects enjoy heavy political protection and support from unions and Green and Leftist political factions.

    • And if they get in trouble for this will the total idiot(s) in the government who came up with a flat rate payment get the same punishment? They ought to as they created a scheme that gives an incentive to such behaviour.

    • 1. That was 2013.
      2. That is a State level tax credit.
      3. If you really looked at the economics of the Wind Farm, you would see how ridiculous your argument is. The tax credit amounts to less than $100,000 per turbine ( $30 Million for 338 turbines GE 2.5 MW) — For turbines that cost about $3 Million apiece (not counting installation) that amounts to less than 3% of construction costs. Profitability of the windfarm is not rising or falling on that 3%.

      • Karl,
        What argument is ridiculous?
        The info about the State credit is included in the link. The facts of the faked subdivision of the wind power operations are well known and documented. Why do you not discuss that?

      • @ Alan — the argument that wind farms are not financially viable without subsidies is ridiculous. Especially ridiculous when you look at the actual amount of subsidies — a $100,000 tax credit per $3 Million turbine.

      • @ Karl- I cannot imagine a more disingenuous answer from you. Since you appear to be an advocate for the wind industry and familiar with the Oregon project, you know full well that the subsidies to Shepherd’s flat are over $1 Billion when Federal grants and subsidies are accounted for, which brings your ramblings into the sphere of propaganda. Add to that wasteful largesse, the fact that Shepherd’s Flat is GUARANTEED a profit of 30% to it’s sole customer, a hostage SoCal utililty which must meet “low Carbon” requirements of that state’s inane laws.
        You’re fond of the word ridiculous- this Progressive wind power scheme is certainly ridiculous, although General Electric, one of POTUIS largest financial backers, is certainly ever so grateful.
        Ps I notice you still haven’t addressed the fact that Caithness Shepherd’s Flat resorted to nefarious means to secure an additional $20 Million of Oregon tax subsidies to which they weren’t entitled.

        • I propose that WUWT autocorrect the word “subsidy” with the words “subsidies and mandates,” because not only is the worthless power subsidized, it is provided with coerced customers.
          Subsidies are only half of the problem. With a mandate, the purchase of the wind is made involuntarily.
          Now, every politician is selling insurance, or worthless wind turbines, or psych meds, or electric cars. Some are selling school supplies, and any “green” eco product.
          And then the politicians have to have glowing reports of the efficacy of their products, which they forced people to buy in their brand new economic paradigm. Did you notice that now the govenrment and NGOs are the only customer any company has to serve? That was it, that is the new economic paradigm.
          Subsidies are the least of anyone’s worries all by themselves. The mandates cause the real catastrophes.

  11. Probably the bigger effect is that wind operators build the best sites first. That gives them the best return on investment. So as more wind capacity is built the next project gets a worse location, and so on. Good locations especially on land are rare:
    The Answer My Friend Is Not Blowing In The Wind
    Consequently ordinary project economics dictate that later wind farms will be less efficient that earlier ones, so as more renewable energy capacity is constructed the more costly will be the resulting energy.

    • Each of the existing units will produce less also, but how much less.
      I think that will be resolved in court again paid for by the suckers, us.

    • This is an over-simplified view.
      Wind development is, first and foremost, dependent on site availability,volunteered by landowners, and any number of GIS restraints which have nothing to do with wind resource.
      Also, speculative wind developers often prefer cheap/easy development sites with good grid and site access and low site rentals. In the UK we have seen development hotspots in Easten and Central England and lowland, Eastern Scotland with low average wind speeds preferred to high wind speed locations.
      High wind speed sites on peat uplands distant from grid connections and end users can be expensive and difficult to develop, so, with an undiscriminating subsidy system such as the Renewables Obligation, developers have often chased easier and and cheaper sites with relatively low wind speeds.
      Quote: “Historically, wind farm developers have chased the windiest sites to optimise returns… Your Energy believes that the Renewables Obligation together with technological advances allow a new approach … (Your Energy Ltd., ‘Moorsyde’ Brochure, 2004). ‘Moorsyde’ would have offered a load factor of 22.4%.

    • Anyone considering putting windmills offshore better be funding it with their own car wash. I suspect that all you’d ever get out of that are some really good fishing/diving spots. It’s salt water and salt spray; the water is moving all the time, some times quite violently.
      Anecdotally, it’s similar to air condition units at our coast condo. About 5 years is the expected life. Once beyond 5 years it’s time to start saving for the next one because it’s going to fail, and it’s going to fail at the beginning of a holiday. You can pay twice as much for a “hardened” unit and maybe get 25% longer but the math rarely works. Then sometimes you get lucky and the weather destroys the unit near the 5 year cycle and you can claim it on insurance. All of the above is fiction based on true events over 30 years.
      Yes oil rigs work, but remember you have a pretty much 24/7/365 maintenance crew on site. I doubt the energy density of the windmill is going to support that cost.

  12. One other thing, from watching wind farm shows on TV and the way those poor sods have to access them on ropes did no one even consider installing steps and a gantry or rotating platform at the top? Talk about a rubbish unsafe design for servicing and maintenance! All they wanted was to reduce costs and made the damned things so impractical, dangerous and expensive to operate, as a result. Where were the design standards? Why were human workers treated like an afterthought? Another technology that was not well thought out, and not ready to go into mass production.

    • I had the opportunity to go up in one of these things (with a bunch of other engineers, a few at a time) We went up and down via a ladder, inside. That is how all that I’ve seen around here are built. Having worked more with water towers, climbing up a ladder and rappelling down the outside (inspecting the paint), let me assure you that those “poor sods” are well paid, and climbing around on ropes 100 or 200 feet above ground can be fun.

  13. That bit of research reporting was about as useful as hinting that you should shelter in a doorway to avoid wind and rain. What a waste of time and no doubt money and I read it – glad is wasn’t so long. The 1km figure is just not sounding right either.
    Just consider when you pass an oncoming juggernaut…the effective wind speed is the combined speeds you and the juggernaut are doing, so guess around 120mph for this e.g.. Within a short distance you will feel wind buffeting from the j/n, but when the distance is only a modest 10ft or so, you feel nothing, zilch, nadder. Air is very ‘fluid’.
    Look at the turbine blades for heavens sake, they occupy so little actual space of their rotational sweep. Where I am there is a windfarm of 70 w/mills and I would guess they are 1 or 2 to an acre 3 or four deep in the minimum ‘shadow’ dimension.

    • Neillusion,
      Since an acre is just 208.7 feet per side and the commonly installed 1.5 MW generators have blade lengths of 200 feet, your example would indicate some curious blade timing to work in that close spacing. One might suggest that it’s time to get your eyeballs to the calibration shop.
      BTW, the tip speed on those behemoths at full tilt is close to 200 mph.

    • In the Tehachapi area (CA), they fit about 3 turbines in 100 acres, more or less. Google will get you there.

  14. “What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?”
    or put another way, just for the climate fundamentalists,
    What happens to the climate when you remove capacity from essential climate mechanisms?

    • It’s below the noise. Not to mention that the overwhelming majority of 70% of the Earths surface will likely never have turbines (non coastal ocean). The cross section of the laminar flow is 140 meters out of 10,000 (10 km).
      What drives the wind happens everywhere, not just upwind of the wind farm.

  15. It’s called “floor seats” for a reason
    Are we allowed to say “No shit, Sherlock?” in these comments?

  16. But as wind turbines proliferate, researchers at the University of Kansas are looking at how these forests of turbines affect the wind itself. What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?

    Has anybody ever done a study on how many butterfly wings it takes to equal one wind turbine?

    • That’s an excellent angle on the subject, Gunga Din.
      And perhaps there is a song in the offing.
      “And I dreamed I saw the thousands of acres of worthless wind turbines
      Riding 100 mph blades in the sky
      They were turning into butterflies
      Within our nation”

  17. So a decent sized building with 1000sqm footprint needs 1 million sqm footprint to service it by a windmill that will only operate at rated capacity about 10% of the time? And that land is useless except for grazing animals you don’t care about given they won’t be healthy. Great policy.

    • There is a lot of corn and beans and other crops growing under and around windmills. The only place that cannot be used for crops is the access road, the area occupied by the base and a parking area.

      • There’s an idea – a combo windturbine drill. That would get the fracking protesters / turbine huggers really confused.

  18. The conclusion described in the title should be blindingly obvious to any competitive sailor. The lead boat has a steady breeze; boats downwind and/or in very close proximity to the lead boat deal with an altered (reduced, irregular, turbulent) wind. A sail is a wing, as is a windmill blade. I’ve often suspected that there must be a degradation of yield for turbines placed close together–like we sailors experience.
    Perhaps there is a model in the works somewhere showing the relationship between turbine placement, yield, and quantity of dead birds of prey…(sarc)

    • Pilots, especially fighter/stunt pilots, can tell you the same.
      Shoot – shouldn’t Environmentalists be able to figure it out based off the flying patterns of migrating birds? Or is that expecting too much of them?

      • Not quite the same. The turbulence behind an aircraft is largely caused by the energy that is being transferred from the engine(s) in the form of thrust, not because the wing is extracting energy to create lift.

      • The turbulence behind an aircraft is largely caused by the energy that is being transferred from the engine(s) in the form of thrust, not because the wing is extracting energy to create lift.
        Not so.
        This aircraft is on the approach. (ie: not much thrust). The main vortices-turbulence always comes off the wing, especially in this configuration with the flaps half down. The airflow rises over the tips of the wing (over end of the flap system in this configuration) and down over the roots, forming a rotation. This is the basis of induced drag, and forms the classic double-spiral contrail behind an aircraft.
        Windelec blades will form the same kind of spiral. But the rotational motion of the blades will spiral those spirals into the hub center. The following flow simulation concentrates more on the tip vortices, for some reason. But as with an aircraft wing, the largest vortex is generated by the interaction of the tip and the root.
        That is why a four engine aircraft will always end up with just two contrails, because the wing vortex always overcomes the smaller influence of the engines, and the very small wing-tip vortex. That is why the windelec contrails in the previous image I posted, forms expanding cones behind the hub of the rotor (see: September 1, 2015 at 12:38 am). It is not the tip vortices that are creating the greatest reduction in atmospheric pressure, and thus generating visible condensate, it is the root.

  19. I wonder if they accounted for the effect of wind-shadow and turbulence?
    I’ve had a sailboat at one time or another, and studying up on these you learn that sailboats produce a wind-shadow. Any boat coming into the shadow will have less “drive” being produced by its sails. The shadow tends to be conic, with the base being at the sailboat producing it and going down to a point as you get further away from the sailboat producing the shadow.
    Put too many turbines in too small a space and you’re bound to get wind-shadow problems.
    Turbulence— these things have three blades, as they come through the air they form tip-vortices where the air over the face of the blade meets the air coming off the back of the blade. At the tip, it forms a vortice not unlike a horizontal tornado– only much weaker of course. These vortices will of course affect any turbine close enough to be in the wake of the unit producing the vortice, and the affected turbine will of course produce somewhat less power because it’s not operating in clean air.
    So– that’s my immediate thoughts based on experience in other areas.

    • The main “cone” from the first turbine need about 10x turbine diameters before the next wind (money) generator cab be considered 90%-100% effective at the given wind speed. Closer than 10x blade diameters? Lower efficiency for the downstream turbine.
      Now, if all are spread across a very perfectly shaped hill aligned right perpendicular to the wind, all will be equally effective. But! That ONLY happens if the wind is that specific direction at the optimum speed? Any other direction? None are effective – all are stalled out and producing 5-10% nameplate power.

    • An article in the Texas Power coop magazine a few months back was talking about how the wind farms (we have lots of them) fail to produce the calculated power at optimum conditions. The turbulence you speak of is the obvious culprit. Texas Tech has been given a multi million dollar grant to study the issue –see if here might be some magic arraignment that would facilitate optimum production. As an aside–every time I drive through one of these farms, I get H.G.Well’s war of the worlds images running through my addled mind.

      • @jvc, “An article in the Texas Power coop magazine a few months back was talking about how the wind farms (we have lots of them)”, fail to produce etc.
        jvc I might be naive, but, I have often wondered about the numbers bandied regarding the number of turbines,all the pictures of acres and acres of them, where they are and how they came to be. Seeing that there seems to be so much opposition, regulations to follow and the apparent ineffectiveness of them. Why I ask? Who the heck is bs ing who in this whole debate? I realize the scam subsidies are a huge part of it but if this is such a scam why is it not being stopped?

      • ASYBOT—recently, (within the past 2 years, a major wind farm sprouted south of Goldwaith, and even more recently (6-7months) another near Comanche. North of I-20 in the Abilene area, the horizon is full of them. These are just what I see in the small part of Texas I travel. You are right about the subsidy scam, and I think that some of the majors (shell, BP) are putting money into them–probably for that very reason. In 2014, about 10% of the Texas grid capacity was wind, and from my observation, that has increased, and will keep growing. Of course, that capacity is only when the wind is blowing — sometimes, the blades are not moving at all, so the Texas grid is mostly reliant on the traditional coal and gas plants.

      • The chances of anything coming from Mars
        Are a million to one
        He said.
        But still
        They come.
        (Courtesy Jeff Wayne, well it would be if I had asked)

  20. If increasing the number of wind turbines reduces the velocity of wind and air movement, what effect does this on the weather and climate? Could this ‘green solution’ be having the effect of many other ‘green solutions’ by making the problems worse?

  21. A restatement of the law of diminishing returns. Which is why diminishing is a law, not just a theory. Kind of like Newton’s law of gravity, since stuff on big old Earth always falls down.
    This comment intended in the spirit (only, not the substance) of Dr. Page’s previous guest post.

  22. 1. It is pretty obvious that windmills reduce convection.
    2. Less convection does mean ALW.
    3. Less convection should mean less violent weather. I blame the East Coast hurricane hiatus on windmills.

    • 4. Less convection also leads to less (slower) energy movement and slower heat transfer.
      5. Less/slower heat transfer means more global warming.
      6. More global warming means we should be building more windmills.
      If we can add another 7 interim logic steps in between item #2 & #6 it could pass for true justification to the zealots that only want confirmation (and have such short attention spans).
      [and what does Andrew Lloyd Webber have to do with anything]

    • Anthropogenic Local Warming is all the non-GHG components of human activity.
      ALW is at least as large as AGW. Converting a forest/grassland to asphalt increases outgoing IR at least 50 W/m2 and peak temperature up to 33°C (if you don’t believe that – lay on the grass during the summer at 1:00 PM – then go lay on the road, when no traffic is coming). According to the Virginia highway department an asphalt road is typically 60°F warmer than ambient temperature at the peak of the day.
      If you compute that 3% of the US is urban (let alone the roads/buildings/cleared fields in rural/pristine areas) that is 1-1.6 W/m2 or about the same as the AGW 1.05 W/m2 since 1900.
      6. More global warming means we should be building more windmills.
      Reduced convection and atmospheric turbulence increases warming. Air is an insulator. Reducing air movement reduces heat loss – increasing local temperatures.

      • Mine was a bit of sarcasm (not towards you or your post) …
        “More global warming means we should be building more windmills” (to stop the warming that is caused by the windmills).

      • “More global warming means we should be building more windmills” (to stop the warming that is caused by the windmills).
        Well, no.
        Conventional wisdom is we should be building large versions of those solar powered fans to replace the convective heat loss created by windmills. Fans are just windmills driven backwards. This would give us maximum convection during the heat of the day.

  23. According to the Dept of Energy the installed capacity of wind generation in US by the end of 2014 was 66,000 MW . Assuming an average of 1.53 mw/ turbine [ range is 0.71 to 1.9 MW /turbine for turbines built between 1998-2013), this means there are about 43 000 turbines in US currently . Well you have seen nothing yet . Obama has decreed that renewables must produce 28% of the power by 2030. .Currently or in(2013), renewables produced only 13.1% of US power.That means that more coal plants will have to be shut down and replaced by renewables like wind and solar The power produced by coal plants in 2013 represented 38.9 % of the total. This will have to drop to 24% of the power produced in 2013. My own rough calculation of what this means is that an additional 3 times more of wind/solar capacity will have to be installed or sufficient capacity to produce about 600 twh by combined solar and wind for a new renewable total of 1141 twh of renewables from the 2013 total of 534 twh)

  24. T-Bone Walker – Call It Stormy
    They call it stormy Monday, but Tuesday’s just as bad
    They call it stormy Monday, but Tuesday’s just as bad
    Wednesday’s worse, and Thursday’s also sad
    Yes the eagle flies on Friday, and Saturday I go out to play
    Eagle flies on Friday, and Saturday I go out to play
    Sunday I go to church, then I kneel down and pray.
    Lord have mercy, Lord have mercy on me.
    Lord have mercy, my heart’s in
    Crazy about my baby, yes, send her back to me.
    good ol’ wind farm blues, slight return.

  25. It’s like they said; “Let’s just ignore the elephant in the room, and focus on that little ant instead. Whee, look at him go!”

  26. There you have it. All those wind farms on the West coast of North America have created the warm water blob off shore because of continued wind energy depletion. Oh, they didn’t mention the climate part?
    Kinda related, but have not heard much about the below for some time.

  27. The way I see it, next after the Age of Wind comes Fun in Feudal Times followed by The Age of Stone Revisited. I don’t really want to know what comes after that.
    My hopes of a flying car in my garage will founder forever, dashed against the rocks of wind technology.

  28. I wonder if wind farms will have effect on down wind rain fall? Take tornados, enough wind farms in Kansas could disturb the formation of tornados which could effect farmers in the Ohio valley. Then again, what do I know, I’m just an old construction worker..

  29. If the earth were not rotating as fast as it does now, the wind would always flow in a north/south direction. Hot air would rise at the equator, flow to the poles, then back again to the equator. It’s the thousand mile air speed due to the earth’s rotation of the rising hot air at the equator , to the zero mph air speed at the cold poles that creates the transverse winds. So, now as we harness these winds, we are slowing the earth’s rotation. We are using up the finite rotational momentum of the earth to simply make cheap energy. We have already passed peak wind, so it’s only downhill from here on. (/sarc.)

  30. What about the climatic effects? Reduced evaporation, more rainfall, more thunderstorms, more fog, more extreme highs and lows in temperature the reduction in wind would cause – sounds like climate change could be made real locally by the solution to mitigate it!

  31. I wonder if watermelons actually considered the footprint exchange from dams to windmills. I wonder if watermelons actually considered the footprint damage between dams and the affects of no-dam-controlled floods unleashed into downstream city-dwelling hippy condos.
    Watermelons need to be careful what they ask for, they just may get what their asking for.

  32. not enti,rely on topic, but. Bloomberg, (or at least one writer) solidly aligned to the CAGW cult, with regular articles touting how wonderful Energiewiende is going in Germany, we need to copy their example, etc. Well here is a Bloomberg article on a totally different category
    Some how this item “… about 25,000 goats froze or starved to death across the region during a bad winter in 2013” was missed by the Global bull warming media machine.

  33. This seems like a good time to review this photo, I consider it one of the most important wind turbine photos ever taken.
    In farming territory, the turbulence downwind of a turbine disrupts the air inversion just above the field. This will reduce the effect of radiational cooling at night and keep the ground temperature higher and evaporate more moisture from the ground.
    So turbines should bring warmer and drier conditions.

    • Thank you for that, Ric, I knew I’d seen it somewhere that wind turbines actually elevate ground temperatures and dry out the land,

      • The picture makes it look like the turbines increase the albedo of the earth – and hence bring some counterbalancing cooling.

    • It appears the air passing through the turbines is lower in temperature, causing condensation, the opposite of what you speculate, Generally, removing energy from air cools it, so this is not unexpected.

      • I don’t think the visible wake is from the pressure effect rafellis is demonstrating. The lowest pressure in the wind turbine photo is just behind the blade, but the lead blade is in the clear. I suspect that the air flow around the rotor level is warmer, moister, and probably supersaturated compared to the the air just above the North Sea water. That air is colder, saturated, and has cloud condensation nuclei from the surface.
        Mixing of the two air levels may be the trigger to produce the expanding stream of fog in the turbine wake.
        Or something like that, I don’t think I’m completely right myself. Perhaps it’s really low-altitude chemtrails spread to attack the fish. 🙂

      • There is a reduction of pressure over the camber of the wing, which is what makes a wing work. The reduction in pressure cools the air, causing visible condensate.

        Same reason a pressurized can cools when the gas is released, or water drips out of your exhaust pipe. PV/T is constant, or PV =nRT. Reduce the pressure you reduce the temperature, which makes sense because you have fewer molecules colliding.

    • And turbine # 3 seems to be slightly ahead of turbine #2 in lane 2, no look! #1 one is inching up a few rotations followed by using a slight variation in the wind direction and his team mate is getting a clear path…
      oh no The one behind T3 is slowing down… and now T 4 in lane 4 seems to be speeding up by 10 kms at it’s tips but his team mate behind has lost sight of him . this is getting exiting…..we are getting up to 0.0003 watts!!!!
      And now a break for our sponsor… Here is AL GORE!!!!

  34. wow … fast shutter = stopped blades flat and downstream turbines are directly inline of turbulent flow, that can’t be good for output, but might be damaging to machinery

    • The photo has been used to suggest a more random placement would give a smoother response to changing wind direction.
      Yeah, blade tips cutting through turbulent flow at nearly 200mph is not the design point!

    • Oh, but cats kill birds.
      That’s the Green response- cats kill birds. That makes it all okay then, right?

      • Oh, and windows. Windows kill birds, so if the cats didn’t get them, they’d die anyway. So everybody that owns a cat or a window is responsible. All is well.

      • Dear jorgekafkazar, Really? are you serious? seriously?
        Cats do not, I repeat, do not kill eagles or any other raptor type bird.
        That statement is right out of the wind lobby handbook.

    • Right.
      At least if your position is anti-wind generation.
      If it is evaluating pros and cons, then looking at actual data should be preferrable to playing the emotion card.
      Isn’t this what we say some in climate science are doing?

      • All of the pro- wind power rhetoric needs to pass a simple test… stop the subsidies for 5 years and see how many wind plants get built. None of the extant wind projects would pay for themselves without heavy subsidies and forced higher utility rates to the consumer.

      • Alan,
        I was not offering an opinion on wind generation per se. Whenever the topic comes up one can count on people bringing up the avian and bat kills and the hypocrisy of environmentalists on that score. Seeing as we operate some rather significant commercial wind generation facilities, I checked to find out what actual data we have on the subject. Reality, at least in the PNW, seems rather far removed from the stories which are frequently mentioned.
        Knowing that, I am simply cautioning folks to base their criticisms on well founded points, with the huge numbers of bird deaths being most likely from projections and models which may have the same capacity for accuracy as GCM’s.

    • Sorry Alan, I did not catch that. My apologies to both of you then, guess I’ll assume more sarcasm next time.

  35. As wind direction varies, quite often turbines are in the wind shadows of those upwind of them. In addition, the downwind turbines actually pile up the wind as it turns them and affects the wind upstream. No mention of the changes in environment of the land under these turbines. With slower wind, it gets hotter down there and moisture can be cooked out of the soil. Crops and animals will suffer.

  36. Is it really necessary to build a gigantic windmill to efficiently extract energy from the wind? Perhaps someone should sponsor a contest for other designs that would be less ornicidal and/or butt ugly.
    Here’s one that just occurred to me:
    How about something like a wind sock with a tunable aperture which cold be used to direct the flow of wind so that it resonates a leaf spring (a “reed”) with a magnet attached to it? The magnet could be situated so that it vibrates inside a solenoid, producing an A/C voltage which could be stepped up to provide incremental torque to a more traditional rotor-and-stator dynamo?
    I realize it would take hundreds of these little “clarinets” to equal the power of one large mill, but on the other hand they have the advantage of operating over a broad range of wind speeds and are totally indifferent to wind direction. Furthermore, they can be manufactured out of synthetic fabric and a few off-the-shelf electrical components, making their mass production dirt cheap. They also do not pose any danger to the wildlife.

  37. The authors report playing around with a “sophisticated model.
    That gives a warm and fuzzy feeling! Try an ‘Images’ search using the phrase.
    Seriously, recall Strunk and White’s classic: “Omit needless words.

  38. As far as Im concerned, file this one under… well, duh
    The change to wind patterns will also…
    -wait for it-
    …change the climate
    The entire nonsensical process reminds me of the “save the whales” campaign. Turns out saving the whales results in more predictors. More predictors then results in the loss of more creatures on the bottom of the food chain – who would have thunk it!
    Anyway, off to picket for the raising of taxes to save the poor Steller Sea Lions, whose population decline is a total mystery to us.

  39. “What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?”…… I would add, in the case of the offshore wind farms, what’s happening with the oceans when their watter is stirred by those turbines and by other “facilities”? I think that this is also a subject we need to analyse, since oceans are the most powerful force on Earth that influence climate. Well, it seems that those wind farms play a significant role in climate change: I’m really interested in your oppinions. Thank you, Anthony, for drawing the attention to this subject!

  40. And if we put millions of wind turbines floating in the middle of the Atlantic and Pacific oceans this will kill the winds from hurricanes and typhoons. Of course they would be used to generate hydrogen fuel…

  41. I have not read all the comments, but make 3 points.
    First, the windfarms already constructed have been already taken the best siting, ie., that which is most windy and/or most conveniently placed for supply needs & coupling to the grid. This means that the windfarms already will be the most efficient/productive, and there will inevitably be decreasing returns on future installation.
    Second, wind is contributing about 3% to the energy mix, but given future targets for renewables, and taking into account the point made above, there needs to be say a 20 to 25 times expansion just to bring wind to about 50% contribution to the energy production mix. So we are not talking about just a small increase in the amount of these installations.
    Third, to date, windfarms have not resulted in the meaningful reduction of CO2 emissions because of the need for backup generation provided by fossil fuel generators. These back up generators are either run at 100% output with energy drawn off as and when wind is not producing. or they are idle but run in ramp up/ramp down mode being ramped up when wind is not producing, and ramped down when it is. The first method of back up produces 100% the CO2 that would be produced by the generator even if no windfarm had ever been built. The second, is akin to driving one’s car in urban conditions rather than freeway/mtorway driving. Although wind on average is such that windfarms can produce about 23 to 265 of their nameplate capacity, this does not result in a corresponding 23 to 26% reduction in CO2 since fossil fuel generators produce almost as much CO2 when used in ramp up/ramp down mode when compared to the amount of CO2 they would have produced if left to run at steady state providing 100% conventional output.
    Windfarms fail on their primary criteria, ie., they do not result in the meaningful reduction of CO2. They are certainly inefficient and fail to produce reliable energy always on tap as needed, so fail on an engineering perspective.
    When this sc*m falls, the biggest fallout will come from the fact that renewable energy has been extremely expensive and never resulted in the meaningful reduction of CO2 in view of the need for conventionally powered fossil fuel generated backup which backup was required (and known to be so) due to the vagrancies of the wind (and/or the fact that the sun does not shine at night and in mid to high latitudes is not particularly strong and does not coincide with peak demand, ie., long winter evenings/nights). This is obvious to any 14 year schoolchild so should be obvious to politicians. Every windfarm application should be accompanied with a report as to the amount of CO2 emissions that the windfarm will save on a yearly basis during its expected lifetime (this should include the CO2 used in its construction and coupling to the grid and backup generation), and what effect that reduction in CO2 is expected to achieve in reducing temperatures going forward.
    PS. I am not suggesting that it is necessary to take steps to reduce CO2 emissions, but merely pointing out that renewables fail on their prime objective, ie., to significantly reduce the CO2 that is produced in energy production.

    • “Windfarms fail on their primary criteria, ie., they do not result in the meaningful reduction of CO2.” But they do job of killing a lot of birds and bats as our politicians and the Audubon Society looks the other way.

      • Their primary criteria is to produce energy. They are easier and less expensive to install and interconnect than Nuclear, Gas, and Coal. You can still use the land they are sited on for other purposes. They don’t generate waste like Coal and Nuclear. They don’t create weaponizable material like Nuclear. They don’t require fuel like Coal Gas and Nuclear. And per Stanford University windfarms can be used for baseload electricity to the grid.

        • Remarkable! You have managed to create an entry propagandizing wind turbines such that each and every sentence is wrong!

          Their primary criteria is to produce energy.

          Dead wrong. The only purpose is to create immediate tax and energy credits and construction profits for their (democrat) political donors snd overseas factories, the unions who put them up and who sip them here for tax credits and deductions. At 16 – 19% production factors, they will wear out from no maintenance (because none is budgeted nor required by the tax credits!) before their 7-9 parts rotor, blade and bearing lifetime expires. Crane, parts, repair time and manpower rental expenses alone to replace a bearing are more than a year’s production of electricity.

          They are easier and less expensive to install and interconnect than Nuclear, Gas, and Coal.

          False. For a field of generators covering 200 – 400 acres, you need tens of miles of high-voltage copper and towers, then a controllers network (remote operated!) and transformer AND a very-high voltage transmission line back to the nearest substation transformer yard and ITS connections. All that for 20 1.5 MWatt “generators” that (on average) produce an irregular output of 16% x 20 x 1.5 MWatts (that equals an unreliable “average” power of only 4.8 MWatts, by the way.) Or you can build a combined cycle 480 Megawatt GT on 20 acres in 1 year with one road with ONE transformer yard connecting to the same grid to generate reliable energy 60 x 60 x 24 x 365 days a year. Paying taxes and generating electricity, rather than USING taxes to generate profits for the politicians’ companies.

          You can still use the land they are sited on for other purposes.

          And pollute the general area with hundreds of miles of ugly monsters. And require hundreds of tons of roads, concrete, electric towers and transformers that are wasted – except for the tax money they send to their owners chosen political parties.

          They don’t generate waste like Coal and Nuclear.

          They waste every pound of insulation, copper, concrete, rock, asphalt, steel, gravel, and rare earth metal extracted from open unregulated pits in China and every Watt of energy wasted building and shipping and installing them. Worse, they deliver (on average) on 1/6 of they REQUIRE to be built – and a guaranteed loss immediately of 83% of their installed mass and its support infrastructure. Plus the pollution left overseas killing people.

          They don’t create weaponizable material like Nuclear.

          Well, your democrats are deliberately making sure the terrorists are supplied directly with enriched pure uranium and the rockets and missiles to deliver it towards the homes of their enemies, so “terrorists” are not so very likely to even WANT to get a useless mix of waste radioactive spoils from US power plant reactor fuels, are they? Plus, your democrat-led fears won’t even let US (who WOULD process them correctly!) to recycle US uranium fuels that WOULD greatly increase future supplies!

          They don’t require fuel like Coal Gas and Nuclear.

          Every wind turbine requires a running reserve be available 60 x 60 x 24 x 365, or kept on standby for the same period at startup rates that destroy the steel forgings and welded exhausts from constant but irregular starting and stopping. A 100 million dollar machine that should run 48 months straight is cracked through in 7 – 14 months.

          And per Stanford University windfarms can be used for baseload electricity to the grid.

          And unicorn horns were reported by scientific consensus to be able to transmute metals. How many government-paid scientists can you buy for 92 billions a year? And your scientific consensus claimed the moon’s craters were volcanic, and completely rejected plate tectonics for dozens of years ….

    • I have to agree with RACookPE1978. My wife and I drove across the country last month, both ways, and on different roads. We observed hundreds upon hundreds of giant windmills, as far as the eye could see.
      That was just on the roads we traveled. Presumably, there are more windmills for hundreds of miles in any direction. They really do ruin the landscape.
      The sole reason for all those monstrosities is government subsidies. If not for the huge tax breaks, those windmills would not exist, at least not the ones used for generating electricity.
      If a technology cannot be supported by a market-based demand, then it is ipso facto inefficient. It is no different in principle from paying people to dig 10’X10’X10′ holes in the ground, and then paying them to move those holes fifty feet away. Windmills are make-work that benefits a few, at the expense of everyone else.
      And they’re as ugly as sin.

  42. We will impart more of the wind energy onto the earth and depending upon where the majority of turbines are, could make the earth spin faster/slower – we’re doomed

    • Why does that pic remind me of Arlington? Maybe it’s a pic of the ‘Alarmington Cemetery’ – where alarmists bury their models.

    • It illustrates that the priority is to build wind turbines; not to extract the maximum amount of energy.
      A return to laminar flow after a flow disruption is 10 to 20 characteristic diameters (in a pipe). Any Engineer who’s studied fluid mechanics since the 1920’s should be able to tell you that. Those towers look like they’re spaced at 5 to 7 “blade disc” diameters. Of course spacing at 10 compared to 7 approximately doubles area and connection costs. And offshore wind is already around double the cost (based on _nameplate_ capacity) compared to land-based.

  43. It’s difficult to imagine, but CAGW is on the cusp of disconfirmation given almost 20 years without a global warming trend.
    In just 5 years, it will be a quarter of a century, with the chance of 25+ year FALLING global temp trend developing by the early 2020’s from: PDO cool cycle, AMO cool cycle and the weakest solar cycle since the Mauder Minimum all kick in at the same time….
    Eventually, all these wind farms will be dismantled and these bird-killers will just be a footnote in the history books.
    CAGW will be looked at as a silly period of human history when the world went collectively insane from the effects of government propaganda and failed statist ideologies….
    We’re getting tantalizing close… CAGW apologists will try to Karl2015 (now a verb) as much as possible, but any additional shenanigans from the alarmists will eventually be legally actionable under fraud and misappropriation of public fund laws…
    The alarmists are running out of excuses, options, money and time.
    Taxpayers just aren’t buying what they’re trying to sell, as poll numbers so clearly indicate.

  44. About 2or 3 years ago there was a considerable concern in the UK about the latest form of arboreal , fungal , disease to affect the country ,affecting ash trees . Since it seemed that the disease was spreading across from Europe by wind action , I wondered what affect the turbulence created by assembles of wind turbines might have on the spread of the disease and overlaid disease concentrations on top of wind farm maps . I convinced myself (but probably because I was already biassed against wind farms ) that there was a coincidence and actually posted a comment about it to the Telegraph (in the days when you did not have to pay them to comment).
    There was one reply that pointed out that in Denmark the incidence of fungal tree disease was extremely high and also coincided with the greatest concentration of wind turbines in Europe (at that time).
    In a country so vast as the US this is not likely to be a problem even if there was the possibility of a link , but in small confined countries like England might this not be worth someone investigating , especially as Oaks, Chestnuts , and Ash appear to joining the Elm in extinction from our country hedgerows.
    (And yes I do appreciate that global warming is also a possible factor).

  45. Here we go. This is an evaluation of wind losses (power losses) as you progress through an offshore array of windelecs (turbines). Look at figs 3a and 3b (3a is reproduced below).
    ER = wind direct along the columns of the array. This gives a 40% reduction in wind, with a 6-row array.
    ER+-10 = wind ten degrees away from the direct angle. This gives a 25% reduction in wind, with a 6-row array.
    So the reduction in windspeed is significant — up to 50% in the worst case. Notice that the models (red line) do not agree with real-world data (blue line), once more.
    The study of windspeeds:

  46. The moral of the story, to summarise, is that if you try to take avantage of Mother Nature she will always come back and bite you on the bum.

  47. Given that wind is the way energy gets re-distributed around the atmosphere- both vertically and horizontally – what do the models say about the impact of very large numbers of turbines on the earths average temperature ??

  48. Diminishing returns?
    I ‘d like to see how much returns are diminished after government, that is taxpayer subsidies, are subtracted.

    • Ask the same question for Nuclear. Even though there have not been new reactors built in years. The US Govt. and electricity consumers are still subsidizing every single plant out there. All Nuclear fuel in the US was created with Govt. Subsidies, and all construction was backed by cheap guaranteed loans.

  49. It’s also well known that the marginal value of intermittent energy diminishes as it takes up a larger percentage of the entire grid.

  50. As wind speeds slow due to large wind farms, more birds will get hit by the blades as they will not have enough wind speed for lift. As the birds hit the blades, a small but perceptible reduction in turbine speed will occur, resulting in a return to normal wind speeds. Working on the model right now.

    • I realize this is sarcasm, but make sure your model uses a proper input for number of bird strikes. Otherwise you will be way off on the turbine speed reduction output.

  51. The main diminishing return is to taxpayers paying for this scheme along with hundreds of other schemes by dear leaders. That includes the ethanol in the vehicles driving out to the wind towers and the unintended but obvious consequences to utility rate payers from setting aside the regulator responsibility for cost control. Let’s see the timeline of rate payers eating nuclear cost over runs followed by wind farms and high-cost versions of solar PV on the rooftops of the 1 percent.

  52. …Wind farms offer diminishing returns as they grow more widespread…
    Actually, the main reason for the diminishing returns is probably that the first wind farms are built on the optimum sites, and the later ones have to use less effective places…

  53. Its a well known fact that windmills planted too close together even on small farms dont acheive the same output as isolated ones: IIRC you need 8-10 diameter spacing between turbines

  54. This topic has been visited here before, very interestingly in a report suggesting that ocean wind farms could tame hurricanes.
    And, as suggested by others above, it would indeed be ironic if wind farms contributed to global warming by reducing circulation.

  55. I was told that at the Techaphi wind park near Mojave when [they] installed more turbines at the top of the ridgeline, it cut power on the ones below by over 5-10%.

  56. In order to get as much installed generating capacity as we currently have from conventional sources, we would need a wind farm in the shape of a square 1,000 miles on a side. I have no doubt that it would produce less than capacity no matter what the wind conditions. But I also wonder what effect it would have on transport of water, biological material (pollen, microbes, etc), and nutrients (minerals). It seems to me that the effect on the environment, aside from the sheer ugliness of such a thing, would be enormous and negative.

  57. Several have touched on a question I raised years ago with Gerald North, a Texas A&M fan of windmills (and industry advisor). What is the effect on weather in San Antonio as all the windmills north extract energy from the wind system? Do cold fronts die out 1 inch sooner? 1 mile sooner? 100 miles sooner? No answer yet…but “the world wonders” just as Admiral Halsey did.

  58. I n a previous track , University of Kansas researchers found
    “Wind turbines generate electricity by removing energy from the wind, so a larger number of wind turbines should result in a slowdown of the winds in the lower atmosphere,” Mechem said.
    The researchers quantified this phenomenon in numerical simulations by applying a sophisticated model normally used for weather forecasting to one of the windiest regions of the United States.
    The team found that a slowdown effect triggered by wind turbines is substantial for large wind farms and results in proportionally less renewable energy generated for each turbine versus the energy that would be generated from an isolated wind turbine.”
    This turbine project is big (150 turbines ) . It would not surprise me if we soon discover that sustained droughts develop down wind for major wind farms and future wind farms of this concentration will be banned

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