As wind-turbine farms expand, research shows they could offer diminishing returns
From the UNIVERSITY OF KANSAS
![Shepherds_Flat_Wind_Farm_2011[1]](https://wattsupwiththat.files.wordpress.com/2015/08/shepherds_flat_wind_farm_20111.jpg?quality=83)
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.
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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:
https://www.awstruepower.com/assets/The-openWind-Deep-Array-Wake-Model-Development-and-Validation1.pdf
http://s13.postimg.org/7g9ru89yf/windelec_losses.jpg
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.
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 ??
I feel plagiarized! I have repeatedly posted about consequences of scavenging wind energy!
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.
It’s also well known that the marginal value of intermittent energy diminishes as it takes up a larger percentage of the entire grid.
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.
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.
…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…
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
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.
Our Children just aren’t going to know what wind is.
SCNR
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%.
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.
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.
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
Wind Farms cause climate change…how rich.
http://wermenh.com/wind/images/vattenfall-image_300.jpg
What safety measures do they have in place to ensure that a Wind Turbine fire won’t trigger a forest fire?
https://youtu.be/54YOaQixRUo
We have wind turbines within 100 yards of the outer-belt in the dead center of an auto-mall. They even advertise look for the wind turbine. Hope it never gets hit my a tornado.
https://youtu.be/-YJuFvjtM0s