Simulation in the 'Journal of Renewable and Sustainable Energy' provides new insight into best arrangement of wind turbines on large installations

The figure shows a three-dimensional visualization of the flow in a simulated wind-farm. The blue regions show a volume rendering of low-velocity wind regions. These low velocity regions are primarily found in the meandering wakes behind the turbines. Credit: JHU LES/Bock/XSEDE

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

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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%.

MattS

The best possible arrangement for designing wind farms can be summarized in one word.
Don’t

Oldseadog

“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.

Gunga Din

Optimally spacing turbines allows them to capture more wind, produce more power and increase revenue for the farm.

====================================================================
“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.

Tim Walker

Modeling the production of static electricity produced from cats would be of more benefit.

Models, models, models … All The Way Down!!

Andre

Hei Anthony.
You reporting from this fantasy world, – how are we going to detect your 1 April joke?

Terry Comeau

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.

Gunga Din

As wind farms GROW IN IMPORTANCE as sources of clean renewable energy

============================================================
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?

Janice Moore

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

Janice Moore

Just a little reminder that windmills, for no net benefit, are killing birds by the thousands — every — day.
Reporting from Tehachapi, CA:

Merovign

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…

Steve R

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.

Janice Moore

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.

Chad Wozniak

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).

Greg

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.

Greg

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.

redc1c4

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

john

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.

Gunga Din

Greg says:
April 1, 2014 at 3:16 pm
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%]

======================================================================
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.

Curious George

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.

Janice Moore

@ Gunga Din (re: 3:34pm) – Thank you for the witty support. Much appreciated. J.

Janice Moore

@ Curious George (3:39pm) — LOL. Yup. Worthless. #(:))

@ Janice Moore:
Actually, Buffett’s corporation, Berkshire Hathaway (BRK.B) stock is doing quite well. The price has about doubled in 30 months ($66 to $125 per share). The A-shares of his stock increased 80 percent in the same period. You are welcome.
Buffett’s recent purchase of 440-plus Siemens 2.5 MW windturbines is valued at just over $1 billion, for a cost per kW of $1000.
Isn’t it odd that Buffett, the investing genius, chose to purchase windturbines and not a nuclear power plant? He could easily write a check for either one, and is one of the few individuals in the world who can actually do that.
In fact, Buffett has a standing invitation for anybody with a big business, several billion dollars worth, to contact him because he wants to buy more very good businesses. His Berkshire Hathaway generates approximately $2 billion per month in cash that he needs to re-invest in other businesses. Isn’t it odd, Janice, that he is not building any nuclear power plants? (That’s not quite correct, actually, he purchased a small interest in one nuclear plant when he bought MidAmerican Energy, an Iowa utility. It came with the deal).

…new insight into best arrangement of wind turbines…
————
I have a suggestion as to where they can put em!

Jeff

“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.”….
Great. First we have Fat Albert, now we have Large Eddy….it doesn’t look like anyone bothered to model the birds… (fowl weather?).
The hottest air of all is coming from these pollyana studies purporting to be science but only harvesting taxpayers money, and pretty much destroying everything else in their wake.
Have any of these “scientists” lived anywhere NEAR these turbines? At NIGHT, when it would otherwise be quiet? During the day, when the shadow(s) does/do a virtual “water-drop-torture” for the poor folks living within range?
I lived near the disaster of the Altamont wind farm, and from a distance, it was almost graceful. Up close, it was horrifying…noise, bird and turbine parts (yep, most of them were broken), etc.
Funny how windmills get a pass on killing Eagles, Raptors, etc., but we probably end up in jail, even if we accidentally did it…..

indpndnt

Lots of anti-modeling comments on here, which makes me sad. This kind of optimization is important in its own right for those people who want to build their own farms. Regardless of anyone’s views on AGW, pushing efficiency of energy production should be a goal we can all agree on. Rotor wake modeling, while still a bit magic, isn’t as shoddy as climate modeling. People still try to make their models match real test data, and the general physical principles (turbulence, friction, etc.) are known to exist, even if imperfectly. Plus, we can build and test smaller scale farms to help validate these models. Can’t do that with the climate!
Contrast that with climate modeling, which we aren’t even sure has all the right physical events occurring. Yes, models are only as good as their assumptions. Some models have much better assumptions. Because of those models, we have helicopters and planes and all kinds of good stuff. Let’s not be against good engineering, and be open to all kinds of ways to supply power.
“What a useful piece of work! ”
It is. Once you have a modeling framework set up that can take in uncertain inputs, you can do a lot of good work in finding robust solutions to real problems.
I’m not for having government-forced and over-subsidized wind farms, but if we can figure out a way to make them efficient enough to be competitive, why not have them?

FightingScallion

I was working in (literally in the test section) of a US Air Force wind tunnel one day, setting up for some testing, when windmills came up. In there, someone asked a question that made us all realize just how odd our perspective was:
How many windmills will be placed before there is a noticeable effect on the earth’s rotation due to the associated drag?
As for this study…it’s not exactly that mind blowing. There are a lot of things they could do to improve things beyond left/right offset. They could also look at the number of diameters downstream that the vortex core has fully burst (where a far field assumption is again valid), counter-rotating windmill staggers, boat-tail design, and maybe some other fun three-dimensional effect ideas.

Jeff

“Greg says:
April 1, 2014 at 3:16 pm
… you may look like you at least had half an idea what you were talking about.”
Greg, it’s not what one “looks like”, it’s what one says.
Civility and courtesy often help in presenting one’s points…
Turbines are often called windmills, by the, erm, “great unwashed” – they are simply a refinement
of a centuries-old machine, not a new one….

Bill McCarter

The boundary layer wind tunnel at the University of Western Ontario did a lot of tests on this in 1976 or so. It turned out that the ideal spacing of the turbines was 28 turbine diameters downwind. Somehow I do not this that the physics has changed in the intervening time.

Gary Pearse

Greg says:
April 1, 2014 at 3:16 pm
Janice Moore says:
April 1, 2014 at 3:00 pm
“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.”
Nice try Greg. Janice’s point is 59% is the best we can do to convert wind energy to MECHANICAL energy. Now we have to convert mechtricityl to electricity. Now would you like to research how efficiently the mechanical is converted to electrical. At 59% you have achieved the best you can get BEFORE it can be converted to power. Would you be surprised that the average Windpower capacity is something below 20%?

Janice Moore

Yes, Jeff, indeed. And, thanks for the support.
I just chuckle at the “Greg’s” and R.S.’s of the world. It really upsets them when someone uses a pejorative characterization of something to which they are committed with all their naive hearts. Wind-MILLS, just like blunderbusses, Model A’s, and 8 track tape players, have had their day, many years ago… .
They are NOW obsolete.
“Large Eddy” — LOVE it. #(:))

john robertson

Given that these windmills have so far failed to return the energy that went into constructing and erecting them, why bother?
A more efficient and there for more ecologically pure solution, would be to just burn the fossil fuels to carry out our tasks.
There is something deranged about wasting resources to build energy producers that do not reward your investment, or provide reliable power.
Must be alternate energy, it works in an alternate universe and on alternate days.

Lawrence Todd

Looks like a perfect arrangement to kill the maximum birds in a flock at the same time

george e. smith

I thought the whole idea behind a wind turbine was to take energy out of the air. ?
So how long has it taken for them to realize that this happens.
So do they disclose this in their environmental impact statement. ??
Can down wind land owners, sue for the loss of wind energy over their properties, and the damage they receive as a result ??

Janice Moore

Thanks, Gary Pearse (btw: HOW ARE YOU DOING, ol’ WUWT buddy, ol pal? Long time not talk! Hope all is well up there!).
Greg obviously did not go to page 7 of that excellent report I linked for him. There, it says (inter alia):
“The capacity factor may theoretically vary from 0 to 100%,
but in practice it usually is 20% to 70%.”
Greg, I guess I did not communicate thoroughly enough. The Betz quote was only the crux of the issue — I left it to you to look up the rest of the science in that source I linked. I didn’t think it would be necessary to write a synopsis of the article for you.
That report is quite brief in itself but has NUMEROUS links to detailed physics/mechanical engineering explanations…. that is, if someone is really interested in LEARNING… .
Re: the discourtesy, Jeff, yes, it is interesting that both windmill promoters, here, G. and R.S., chose to call me “Janice” without my permission. I would think that Ms. Moore would have been the respectful thing to do… . AND THAT’S JUST FINE! They are doing a GREAT job of showing what type of person is in favor of forcing taxpayers to subsidize anachronistic technology!
BTW: All you guys who know I don’t mind your calling me “Janice” — please do continue to do so!
#(:))

Jeff

“Roger Sowell says:
April 1, 2014 at 4:25 pm ”
Warren Buffet is simply doing that which nets him the most money. Whether it is scientifically, environmentally, or philosophically (as a catchall term) correct to do is of limited or no interest to him. BH is in the business of making money, often from those of us who have substantially less than Mr. Buffet.
Those who travel in the circles that he does (often meeting at Davos or Bohemian-club-type affairs) can influence the investment enrvironment simply due to the size of their investments and their connections, etc.
That doesn’t make it “right”, on a number of levels. He could probably shake up the carbon credit market, if he felt like it. Wasn’t that long ago that the Hunt brothers made substantial waves in the silver market – it could well happen again, different folks, different markets.
All of his money won’t cure the blight the turbines make on the landscape, nor will it bring back the birds killed by them. And, as I said elsewhere, they are not pleasant when they are nearby (and I doubt that he would want one in his backyard(s)).
Again, a questionable solution to a nonexistent problem costing more money than it’s worth
(cf. Cameron in the UK and his subsidised “farms”).

Janice Moore

Dear Mr. George E. Smith (I’d better take my own advice!),
How is your sister? I prayed. Hope all is well. And how is college going for your son?
Your WUWT pal who hopes you will call her,
Janice

PaulH

I wish they would stop calling these industrial wind installations “farms”. They are most definitely NOT farms in any sense, as there are no agricultural activities at these compounds.

F. Ross

Roger Sowell says:
April 1, 2014 at 4:25 pm
“…
Isn’t it odd that Buffett, the investing genius, chose to purchase windturbines and not a nuclear power plant? He could easily write a check for either one, and is one of the few individuals in the world who can actually do that.

[+emphasis]
I have followed and read many of your very cogent posts on WUWT, but in the above statement don’t you think that Buffett’s choice between wind and nuclear would be largely related to the very involved permitting process in anything “nuclear”?

Jeff

“PaulH says:
April 1, 2014 at 5:41 pm
I wish they would stop calling these industrial wind installations “farms”. They are most definitely NOT farms in any sense, as there are no agricultural activities at these compounds.”
Yes, a better term perhaps would be “anti-farm”, or anti-creature. I do believe there was some effort to do ranching near or on the Altamont land (I won’t get into the farming versus ranching debate going on over there…).
Unfortunately “farm” has become a collective noun for a number of things in the computer industry (render farm, server farm, in the old days modem farm….) and other industries as well. I suspect most of the folks in the non-agricultural businesses have not actually “farmed” in the real sense of the word….(sad, that)…
If all these carbon taxes, etc. keep siphoning off our money, we may all learn about REAL farms, whether we want to or not….:) or was tnat :(…..

Curious George

I like the ideal spacing of turbines: 28 rotor diameters downwind. We know! Now let’s make sure the wind blows always from one direction .. or maybe we can rotate the landscape .. and we can always use an eminent domain to build a turbine another 28 rotor diameters downwind.

May as well introduce some economic reality I suppose. Just finished an article published by the AmericanTradition Institute called “The Hidden Costs of Wind Energy” which examines all those nasty side effect costs that wind proponents never seem to include in their estimates of costs.
In short, the study starts off with the costs of the turbines, actually using a lower estimate than used by the Energy Information Agency (EIA). But then it knows enough to take subsidies into account, as well as the costs of maintaining backup plants, as well as the increased fuel costs at those plants (per unit generated) and finally the transmission costs, both now and in the future
as wind farms spread out geographically. They also discovered that the cost of wind depends upon whether coal or natural gas provides the backup capacity. There figures show the total cost of wind (kWhr) when backed up by coal to be 19.2 cents and 15.1 cents when backed up by
natural gas power plants. My research into the unit production costs expected from Gen 3 + power plants (those currently being built) has provided me with confidence that the costs will approximate 4 cents per kWhr here in the U.S.(a little more or a little less), but less in China and Russia and India (probably closer to 3 cents per kWhr, due primarily to lower build costs and operational costs). Since nuclear fuel costs are unlikely to increase (and also
constitute a relatively small portion of nuclear generation costs, so any increases will not
significantly affect retail prices) the costs of nuclear power should be quite steady, as it has been for decades.

asybot

@ george sowell : Even he needs a tax write [off] at times! ( and being in his eighties is allowed a mistake or two 🙂 )

asybot

,sorry “write off” , (Gee and I am only 62 🙂 ).

@ F. Ross at April 1, 2014 at 5:48 pm
I have followed and read many of your very cogent posts on WUWT, but in the above statement don’t you think that Buffett’s choice between wind and nuclear would be largely related to the very involved permitting process in anything “nuclear”?”
My comment was made primarily to annoy Miss or Mrs or Ms as the case may be, Janice Moore, who is so easily offended yet speaks disparagingly as she (one presumes the feminine gender, but one never knows) pleases. It is a carry-over from earlier posts and her sharp exchanges whenever “noocular” energy is mentioned. “Noocular” energy is the end-all, be-all, and Lordy-its-gonna-save-us-all choice for power generation, if one were to ask Miss/Mrs/Ms Janice Moore. It’s a Pavlovian response, a hot button, apparently. Just watch, Moore will go ballistic (dare I say Nuclear?) in her responses below.
As to your question on Buffett, I suspect that he can navigate the permitting requirements quite well, should he choose to do so. It is also interesting, given that he has been a premier investor for nearly 50 years, that he has never purchased a nuclear utility even when they were the darlings of the utility industry. He could have, but he did not. Surely, that says volumes about the profit potential of nuclear power plants.

kevin kilty

Greg says:
April 1, 2014 at 3:16 pm

The claim to greater efficiency in the tree-leaf solar panel was in reality a mistaken method of calculating efficiency.

lee

It is also interesting that Buffet is into oil carrying railway cars. Which tends to suggest he believes in spreading the risk. Not an intrinsic belief in wind power.