From the Wind energy: On the grid, off the checkerboard
WASHINGTON D.C., April 1, 2014 — As wind farms grow in importance across the globe as sources of clean, renewable energy, one key consideration in their construction is their physical design — spacing and orienting individual turbines to maximize their efficiency and minimize any “wake effects,” where the swooping blades of one reduces the energy in the wind available for the following turbine.
Optimally spacing turbines allows them to capture more wind, produce more power and increase revenue for the farm. Knowing this, designers in the industry typically apply simple computer models to help determine the best arrangements of the turbines. This works well for small wind farms but becomes less precise for larger wind-farms where the wakes interact with one another and the overall effect is harder to predict.
Now a team of researchers at Johns Hopkins University (JHU) has developed a new way to study wake effects that takes into account the airflow both within and around a wind farm and challenges the conventional belief that turbines arrayed in checker board patterns produce the highest power output. Their study provides insight into factors that determine the most favorable positioning — work described in a new paper in the Journal of Renewable and Sustainable Energy, which is produced by AIP Publishing.
This insight is important for wind project designers in the future to configure turbine farms for increased power output — especially in places with strong prevailing winds.
“It’s important to consider these configurations in test cases,” said Richard Stevens, who conducted the research with Charles Meneveau and Dennice Gayme at JHU. “If turbines are built in a non-optimal arrangement, the amount of electricity produced would be less and so would the revenue of the wind farm.”
How Wind Farms are Currently Designed
Many considerations go into the design of a wind farm. The most ideal turbine arrangement will differ depending on location. The specific topology of the landscape, whether hilly or flat, and the yearlong weather patterns at that site both dictate the specific designs. Political and social considerations may also factor in the choice of sites.
Common test cases to study wind-farm behavior are wind farms in which turbines are either installed in rows, which will be aligned against the prevailing winds, or in staggered, checkerboard-style blocks where each row of turbines is spaced to peek out between the gaps in the previous row.
Staggered farms are generally preferred because they harvest more energy in a smaller footprint, but what Stevens and his colleagues showed is that the checkerboard style can be improved in some cases.
Specifically, they found that better power output may be obtained through an “intermediate” staggering, where each row is imperfectly offset — like a checkerboard that has slipped slightly out of whack.
This work was funded by the National Science Foundation (grant #CBET 1133800 and #OISE 1243482) and by a “Fellowship for Young Energy Scientists” awarded by the Foundation for Fundamental Research on Matter in the Netherlands. The work used XSEDE (NSF) and SURFsara (Netherlands) computer resources.
The article, “Large Eddy Simulation studies of the effects of alignment and wind farm length” is authored by Richard J. A. M. Stevens, Dennice F. Gayme and Charles Meneveau. It will be published in the Journal of Renewable and Sustainable Energy on April 1, 2014 (DOI: 10.1063/1.4869568). After that date, it can be accessed at: http://tinyurl.com/n9o282o
At the big wind park at Techachapi the new turbines at the top of the ridge cut the wind flow to the older turbines below by 10-15%.
The best possible arrangement for designing wind farms can be summarized in one word.
Don’t
“As wind farms GROW IN IMPORTANCE as sources of clean renewable energy ….. “.
Well, I suppose it is still the morning of the 1st. of April somewhere.
Cal Tech had a similar study in 2011, reported on here:
http://wattsupwiththat.com/2011/07/16/location-location-location-wind-turbine-power-output-increased-10x/
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“Optimally spacing turbines allows them to chop more birds, produce more intermittent power and increase subsidies for the farm while reducing actual crop land.”
There. Fixed it.
Modeling the production of static electricity produced from cats would be of more benefit.
Models, models, models … All The Way Down!!
Hei Anthony.
You reporting from this fantasy world, – how are we going to detect your 1 April joke?
It makes sense to me at a glance that you do not position the turbines to get optimal exposure to the prevailing winds. Getting blade movement from the prevailing winds is easy and there is plenty of prevailing wind time. It’s the non prevailing wind time that you need to work at to get better overall efficiency. The difficult part is getting max output when the winds are not from the prevailing direction. So you would want to optimize wind harvest from the non-prevailing directions. Which to me means setting up turbines in a straight line into the prevailing directions, so when the winds are not from the prevailing direction they are more at a checker board pattern into that wind. Overall efficiency will go up.
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I read that it’s been proposed to cut the subsidies to solar power farms. Opponents of the cuts say that would devastate the solar power industry. Maybe that’s why wind farms will grow importan$e?
As if this is a new issue. (eye roll)
Just another transparently obvious publicity ploy to bolster the stock price of the windmill investors. THAT is why Warren Buffett announced his huge order of Siemens windmill technology last fall. He has that kind of cash to throw at a failing part of his portfolio in order to create the illusion that windmills are a going concern (desperately, oh, yes, DESPERATLY, trying to shore up that ol’ stock price … watch him sell …… any day now……..) — Ha! Only the very naïve and ignorant (of the reality of what is happening around the world with tax subsidies for windpower) will be fooled. SELL NOW! Windmill-based investments are headed dooowwwwn.
Wind’s ROI (without heavy taxpayer subsidies) is ETERNALLY NEGATIVE.
Here’s why — Windmills, no matter how you arrange them on the chessboard, ARE NEVER GOING TO BE EFFICIENT SOURCES OF ENERGY (for the modern world):
“Electricity Costs — the Folly of Windpower” by Ruth Lea
{an economic analysis}
http://www.civitas.org.uk/economy/electricitycosts2012.pdf
Just a little reminder that windmills, for no net benefit, are killing birds by the thousands — every — day.
Reporting from Tehachapi, CA:
When the power and materials used to make giant windmills are free, then windmills will be an efficient way to generate power, which you won’t be able to sell, because it’s free.
I’m not saying it will never ever be possible, I’m just saying lottery tickets may be more efficient in the near future.
Countdown to the next Airborne Wind Turbine proposal in 3… 2… 1…
Is there ever any concern expressed about the possibility of wind turbines affecting the weather at the local level? If you harvest enough of the winds energy, I would think it would transform from a geostrophic-like to friction dominated just downwind of the wind farm, with an associated hook to the left. Not sure what difference that would make to anyone, might be interesting to study though.
And some physics to explain why windmills are eternally inefficient:
“Betz’ law (Year 1919) says that one can only convert not more
than 16/27 (or 59%) of the kinetic energy in the wind to
mechanical energy using a wind turbine.”
Source (at page 4) : http://www.engineering.uiowa.edu/~ie_155/Lecture/Energy_Output.pdf
{Thank you to D. J. Hawkins who posted the above link here: http://wattsupwiththat.com/2012/01/10/theres-a-reason-the-modern-age-moved-on-from-windmills/#comment-860177}
This probably is also the optimal method for arranging the turbine to produce the greatest
bird killings. I still wonder where those Whooping Cranes went to that apparently have been lost track of. My guess is that wind turbines are driving them to extinction.
Now if they could only find a way to ensure a constant suppy of wind.
Not clean (death to birds and ground-dwelling creatures alike, a whole new array of pollutants); not renewable (zillions of acres of land consumed in these monstrosities – plus any amount of not exactly renewable fossil fuels burning for spinning reserve and quick start units).
Recently a school student won a prize for a solar powered streetlight design that used many small cells distributed like leaves on a tree. He figured that trees have worked out the most efficient arrangements to catch solar energy and they don’t line up their leaves or have them all point the same way.
He was right. It produced more energy per day than a fixed flat panel oriented due south.
My guess is that this is the same kind of effect.
Janice Moore says:
April 1, 2014 at 3:00 pm
And some physics to explain why windmills are eternally inefficient:
“Betz’ law (Year 1919) says that one can only convert not more
than 16/27 (or 59%) of the kinetic energy in the wind to
mechanical energy using a wind turbine.”
Great work Janice. You’ve just discovered that converting energy from one form to another is not 100% efficient. Now would you like to research how efficiently burning gas or coal or uranium fission is for producing electricity and post the answer. [Hint it’s less than 59%] While you’re there how efficient is an internal combustion engine at converting chemical energy into vehicle kinetic energy? [Hint it’s less than 59%]
Also if you learnt the difference between a windmill and wind-turbine you may look like you at least had half an idea what you were talking about.
i put this link in the “Tips” page a few weeks back, but maybe folks on this thread will find it interesting the USGS has apparently mapped all the wind turbines.
http://www.usgs.gov/blogs/features/usgs_top_story/mapping-the-nations-wind-turbines/?from=title
One of the main problems with wind is turbulence Intensity (TI). This measurement had been used in wind studies for years and I cannot believe that these idiots have never considered it (I know they do what they do for money), and were dishonest enough to omit that very important aspect.
Factors that contribute to this (TI) would be areal terrain and other obstructions. For those who need to visualize this. You car is most efficient driving on nice paved, level ground. Then try this driving down railroad tracks. It will reduce the fuel you use substantially (efficiency), AND more importantly, beat the hell out of you car.
That is what happens. I’ve measured it.
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If only those less efficient forms of energy could supply the steady flow of electricity that the power grid depends on like those windthings do.
From the article: “It should be noted that this work does not claim to provide or propose an optimal layout of wind farms in general. Determining the optimal layout of an actual wind farm depends critically upon annual distributions of wind alignment, site-specific wind roses, and is beyond the scope of the present work.”
What a useful piece of work! Renewable energy at its best.
@ur momisugly Gunga Din (re: 3:34pm) – Thank you for the witty support. Much appreciated. J.
@ur momisugly Curious George (3:39pm) — LOL. Yup. Worthless. #(:))