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
Wind-pinwheels remind me of something — ah, yes. Something that spins and gets nowhere.
Allow me to ‘blue pencil’ this:
“Optimally spacing SIMULATED turbines allows them to capture more SIMULATED wind, produce more SIMULATED power and increase SIMULATED revenue for the SIMULATED farm.”
Greg says:
April 1, 2014 at 3:16 pm
==============
Wind mills or wind turbines are not efficient as you have to build a back up that is able to handle the max load. So you pay twice for wind.
@jake 1:35am.
My uncle has a hybrid, which at 5 years old and less than 50k miles has had to have a new battery pack. A friend’s Lexus hybrid has had to have a new inverter and control system (at a weep making cost). My diesel family car is 12 years old, has done just shy of 180k miles without anything other than regular maintenance, and still does 55mpg on average. I will take a lot of convincing to switch to electric. But if I could get an electric for the school run that cost as much as an equivalent diesel with a 200k miles battery pack, I’d be more than happy to give it a shot.
It may well happen. People who make predictions about the future based on current understanding and technology are always wrong 🙂
Jake J,
“There is definitely a market for shorter-range commuter cars.”
I agree, but most of that market uses cheap used cars for that purpose. The largest segment of that market can’t afford to spend $20K+ on a short range commuter car as a second vehicle.
Unless you can get the total vehicle price under $10K, which will probably require a battery price under $1K, maybe even under $500 that market isn’t large enough to make a significant dent in the consumption of oil as a transportation fuel.
Until that do everything electric car is a reality, EVs will be a tiny niche segment too small to impact the aggregate transportation fuel mix.
george e. smith,
“And what to rare earths have to do with battery technology”
There are a few exceptions, but most rechargeable batteries are made using rare earth elements, the most common being lithium.
“””””…..MattS says:
April 2, 2014 at 8:36 am
george e. smith,
“And what do rare earths have to do with battery technology”
There are a few exceptions, but most rechargeable batteries are made using rare earth elements, the most common being lithium……”””””
I don’t know of a single; even experimental, battery chemistry system, that uses rare earth elements.
Lithium is NOT a rare earth element; it is the first and lightest of the Alkali Metals in group I of the periodic table.
The rare earth elements are the transition series from Cerium, # 58 to Lutetium, # 71, and Lanthanum, # 57, is usually included for some reason I don’t understand.
Lanthanum, is an important Optical glass element, with very nice optical properties, but no use in batteries.
Rare earth elements are common components of modern phosphor materials, as used in lighting, and some display technologies.
Cerium for example, as a dopant in a YAG crystal powder phosphor, is the most well known combination used for white LEDs (patented by Nichia). It has a strong but narrow blue absortion at 460 nm, and radiates a broad yellow centered spectrum, that combines with the residual blue to give white light..
But no use in batteries.
“””””…..Jake J says:
April 2, 2014 at 12:30 am
When you say conversion and storage, that to me implies that your 75% includes the house AC to DC conversion, the charging efficiency of the battery, and the battery to electric motor, and transmission losses.
All of that except for transmission losses, which are 6-7%. I don’t include them because to include electricity transmission losses would require including the energy expenditure in moving gasoline from refineries to pumps. …..”””””
Jake you misunderstood me ( or I wasn’t clear) By “transmission losses”, I did NOT mean the grid transmission from coal plant to house; I was referring to the “mechanical transmission” from auto electric motors, to the drive wheels.
I agree with you, electrics aren’t burdened by the power line costs or losses, any more than gasoline/diesel, is by trucking costs.
Also in fairness, the coal to line juice is no different from Arabian crude processing to diesel and gasoline.
Yes regular autos also have transmission losses. I was trying to see how you get 75% efficiency from AC line juice, through AC-DC conversion, battery charger losses, battery charge-discharge chemical efficiency losses, battery internal series resistance losses on charge and discharge (source of battery heating), battery DC to three phase AC losses (either rotary inverter as in Tesla-S, or electronic DC-AC three phase), three phase AC motor copper (resistance losses, and iron magnetic hysteresis, and eddy current losses (source of electric motor heating), and then the mechanical transmission (including differential) friction losses to the wheels.
If all of that is better than 59% efficiency, that would surprise me greatly.
Two articles that shed a little light on the rare earth element issue. It might be more in the motors than the batteries, but I’m not entirely sure of that
http://www.plugincars.com/rare-earth-elements-arent-actually-necessary-evs-or-hybrids-107194.html
http://www.slashgear.com/ford-reduces-the-use-of-rare-earth-metals-in-lithium-ion-batteries-for-hybrids-13247415/
“””””…..Jake J says:
April 2, 2014 at 12:26 am
@Matt S, the market for electric cars is not going to be all-or-nothing, Very few things are. It started with hard-core geeks 20 years ago. Now it’s early adopters, the curious, and status-seekers, i.e., the Tesla Model S buyers.
Stick a 60 kWh gas tank in the vehicle, and make it cheap enough, and the next segment will be second-car commuters. Not all of them, but a much bigger segment than today. (A 60 kWh battery will deliver a rock-sold 140-mile practical winter range in 90% of the United States, “practical” meaning how far it’ll go on 80% of the battery’s power.)…..”””””
Tesla claims that the Model S with 80 KWh battery gets 300 mile driving range.. EPA, says only 280 miles.
I say, only 90 miles. Once you drive, that model S out of your garage, the only place you can depend on finding an “elecgas” station, is back home in your garage. So you can drive (anywhere) for about 90 miles, and then do some loitering / shopping / sightseeing / whatever, and then drive the 90 miles back home to your elecgas station in YOUR garage.
Try to convince a carrier fighter pilot that he has a thousand mile driving range !
I agree, but most of that market uses cheap used cars for that purpose. The largest segment of that market can’t afford to spend $20K+ on a short range commuter car as a second vehicle.
I’m not a car marketing specialist, but when there are 35% of households with two cars and 20% with three or more, I think some of ’em are buying or leasing new second cars. In any case, the proposition is going to be tested soon, maybe within five years or less.
Bigger batteries are coming; Nissan’s LEAF is reported to be on the brink of doubling battery size for a small ($4,000) price increase. It’s not the holy grail, but if and when it happens you’ll see a whole lot more of them around. Depending on who you believe, this could be announced this year for their 2015 car.
A 48 kWh LEAF would get, on 80% of the battery, a solid 110-115 miles in cold weather; 135 miles on average year-’round; 150 miles in warm weather without A/C; and 140 miles with the A/C. I happen to think 60 kWh is the tipping point, but 48 kWh would be a very big deal, especially if that car would lease for $250 or $300 a month.
Won’t be for everyone, but they’ll sell 500,000 to 1 million a year, and their competitors will be falling all over themselves to match it.
“””””…..Jake J says:
April 2, 2014 at 12:16 pm
Two articles that shed a little light on the rare earth element issue. It might be more in the motors than the batteries, but I’m not entirely sure of that
http://www.plugincars.com/rare-earth-elements-arent-actually-necessary-evs-or-hybrids-107194.html
http://www.slashgear.com/ford-reduces-the-use-of-rare-earth-metals-in-lithium-ion-batteries-for-hybrids-13247415/……””””””
Jake, I’m pretty much in agreement with the first article ; Neodymium, is a well known component of high strength permanent magnets. I’m all for using it in permanent magnet applications, including (very) small electric motors, but it is absurd to use it for power motors. Tesla uses a three phase AC induction motor, with I believe, variable frequency drive. For such motors, it can be shown, that the highest efficiency, for a given size, is reached, when the copper losses (electrical resistance), and the iron losses (hysteresis, and eddy currents), are equal, so 50% of the heat is produced in the coils, and 50% in the iron. You can put in more iron to reduce the flux density, and thus iron losses, but now you have less winding space for the coils, so you have to use a smaller wire gauge, and the copper resistance losses go up, more than the iron losses come down; and of course verse vicea.
Whatever one thinks of the Tesla, from a business point of view, (I think it sucks for the taxpayers), the car is very well engineered; it impresses me, although I would have used two motors, and no differential.
george e. smith, I am utterly not the Tesla salesman. It’s a $100K car for Silicon Valley snobs and wannabes. Tesla is not a car company. They’re a one-product wonder, selling an iPod on wheels. If electrics have a future, they’ll be made by real car companies, not Tesla.
That much said, the 80% range of Tesla’s 84 kWh Model S is about 210 miles. More like 240 miles in warmish weather w/no climate control, and 160 to 180 miles in winter, depending on how harsh. The 90-mile range estimate is as much b.s. as is Tesla’s 300-mile top range claim.
90% of electric recharging is done at home. I think it’ll be close to that for a long time, and maybe forever. That goes for Tesla’s “superchargers” as well. They’re a promotional gimmick, not a practical solution. Even at their higher power levels, a Model S relying on those chargers will spend one-sixth of a road trip sitting at a charger, which is three to four times as long as a gas car.
You asked about efficiency from plug to wheels. On that one, I have to admit that I relied on an electric engineer acquaintance, along with anecdotal semi-confirmation by way of Nissan’s “car wings” website, which purports to tell people how much juice their LEAF uses.
The EE told me the loss between the plug and the wheels is 22%, most of it occurring at the AC to DC conversion point in the car’s inverter, which recharges the battery. There are also losses in the wiring connections between the inverter and the battery, and the battery and the motor. The motors themselves are quite efficient, or so I was told.
Nissan’s “car wings” site works by transmitting a LEAF’s data to a website. Apparently, it measures power AFTER the inverter stage, and gives vastly inflated fuel economy numbers as a result. Therefore, when looking at this issue, I insist on metering the electricity at the outlet with an appliance meter and using the old-school odometer division arithmetic. This is directly comparable to gas pump-odometer arithmetic. It is also the method that the EPA uses.
If you compare like to like on cars, and use Dept. of Energy data to translate gasoline energy content into kWh, you will see that electric cars get 3 to 3-1/2 times the fuel economy. This matches other material out there that talks about the degree to which internal combustion engines waste >75% of their energy by sending heat into the air.
Some of the numbers I’ve given here are imprecise. For instance, electric vehicle efficiency might be better than 75%. Maybe a little worse. Gas car efficiency is probably worse than 25%. But the relative efficiencies are quite reliable, because you can easily compare a Nissan Versa to a Nissan LEAF, using EPA numbers that rely on the Dept. of Energy’s electricity/gas conversion equation.
Also, with respect to windmills or wind turbines or the antichrist with rotors of whatever someone wants to call them, I will maintain that if they are 59% efficient at converting wind energy to electrons that’s damned good and frankly a lot higher than I’d have thought. In the end, though, I’d look at costs, which for terrestrial wind, um, appliances, are surprisingly attractive. I’d also be interested in the lifecycle energy budget (energy in, energy out), but I don’t have the numbers.
Finally, I return to my original point, which is that non-fossil fuel power sources, and electric vehicles, and other innovations that don’t depend on fossil fuels or that use their output more efficiently, are not, not, NOT contradictory with AGW skepticism. To the extent that some eco-faker thinks they can rip out all the fossil-powered electricity generators and replace them with solar and/or wind, then that fool needs to be laughed or argued into submission, depending on who they are.
But that does NOT somehow kill the case for the efficient use of resources, or for engineering, modeling, science, inquiry, and re-engineering. Those things are the building blocks of modern society, which I presume the people around here would like to preserve and extend.
As for as electric car subsidies go, I think too much has been made of them by their opponents.
Why former Confederate States are almost completely free of these industrial devices while the rest of the country is infested by them? Can anyone help me out on this puzzle?
First off, Texas was a member of the confederacy. Check your map again. As for the rest, that’s a good question. This is a complete guess and could easily be wrong, but I wonder if it might be that the deep South doesn’t get all that much wind. What surprises me is that North Dakota isn’t entirely covered with them.
Won’t be for everyone, but they’ll sell 500,000 to 1 million a year, and their competitors will be falling all over themselves to match it.
I wanted to retract the numbers there. I don’t know how enough about the car market to guess how many they’d sell if the have a $33K LEAF before the rebate with a 48 kWh battery. But I do think it would be a very, very, very big deal.
The Bermuda “high” is a persistent, months-long high pressure system that – obviously – stably sits right over Bermuda for many seasons. It is wide enough to influence FL, SC, southern and eastern GA directly, and to a slightly lesser extent, NC, northwest GA, AL, and to moderate the winds even over Mississippi and eastern Arkansas. So, you have many months of the year with very little stable winds and no consistent-direction strong winds at all. What mountains exist are not in the right position and direction to funnel winds through gaps or passes.
West Arkansas, northwest Arkansas will behave much more like northeast TX and east OK …
That leaves northwest TX and coastal TX as the only places in the confederacy where the enviro’s want to keep killing more whooping cranes and migratory birds.
One other thing I’d say is this: The use of petroleum and natural gas, coal, and uranium for energy is appropriately considered a necessary evil. If we could replace these sources with something(s) else that has fewer externalities, we ought to do it, depending of course on what the new externalities are.
We’re not there yet. It’s obvious that we’re not, regardless of what the eco-fakers say. However, we’re starting to nibble around the edges, and maybe more than just nibble in some places. I think it’s a big, big mistake to equate AGW skepticism, which I increasingly share, with opposition to the development of renewables.
Given that renewables are, well, pretty new, there’ll be some level of subsidy involved. In the U.S. the subsidization of emerging infrastructure, whether it was transcontinental railroads, air travel, semiconductors, ubiquitous telecommunications networks, mechanized agriculture, mass higher education, or the interstate highways, is very firmly within our national tradition.
From what I can see, the blind alleys (and stupid mistakes, i.e., Solyndra — what were they thinking?!) notwithstanding, there isn’t a lot of difference between renewables subsidies thus far and the others. Frankly, thus far, my own biggest objection is the ongoing tendency to grant zero value to scenic landscapes when it comes to siting windmills. Other than that, I can live with the rest. Now if I were in Germany I think I’d be a little pissed at putting solar panels in the north Fifties, but I’m not in Germany.
That leaves northwest TX and coastal TX as the only places in the confederacy where the enviro’s want to keep killing more whooping cranes and migratory birds.
I have scenic objections to windmills, but birds? Please, be serious. There are a zillion (okay, 10,000?) of these ugly bastards just east of the scenic boundary along the Columbia River, home to eagles, ospreys, herons, and so on, and it really hasn’t been an issue. But they’ve ruined some vistas, and I’m one of those fools who takes “America the Beautiful” more seriously than the big city eco-fakers and their “progressive poser” windmill corporate buddies.
But the birds? Sorry, pardon the pun, but that one doesn’t fly.
george e. smith, I’m sure it’s obvious by now that I’m not an engineer, but just someone who was good at arithmetic and who scored high on those “general reasoning” tests. But you seem to have a engineering background of some kind, so a question: Are there meaningful opportunities to reduce losses in electric battery propulsion systems?
Are inverters as efficient as they can get?
Can wiring be better shielded, or use different gauges, or otherwise be re-engineered?
Etc.
“”””””……Jake J says:
April 2, 2014 at 2:18 pm …..”””””
Jake, from a chemistry point of view, there is not a great deal of moving room in battery technology.
Different chemical elements (or compounds) exhibit different “electro-chemical potentials” when compared against some standard electrode; which by convention is a hydrogen electrode; if you can imagine that.
For example, a metal like zinc, often used in primary batteries, has a potential (against hydrogen) 0f -0.76 Volts, while copper has a potential of +0.35 Volts.
A copper zinc battery thus generates about 1.11 Volts (open circuit), in an ancient battery called a Lechlanche cell. So the battery Voltages available, depend almost totally on the elements in their electrodes.
Now zinc is known to dissolve rather rapidly in sulphuric acid, and that happens as it generates an electric current. The more chemically reactive an element is, the higher the Voltage it generates.
Lithium, is the start of the Alkali metal series, which is Lithium, Sodium, Potassium, Rubidium, and Cesium. The heaviest member, Francium, is not found in nature.
All of those react violently on contact with water, and or oxygen, generating enough heat to melt the metal, and eventually for it to catch fire. A tiny sliver of potassium, tossed in water, is a sight to behold. So the better they are at making high energy batteries, the more obnoxious an dangerous they are, besides other environmental hazards.
So Lithium, is already one of the most obnoxious, reactive chemicals there are. At he other end of obnoxious, in the reverse direction, you have the elements, Fluorine, Chlorine, Bromine,
Iodine, and fluorine is king of obnoxia for that set.
So the available practical chemical systems, are fairly well known, with not much haggle room.
Where improvements may lie, is in the manufacturing and construction methods and processes.
Small, efficient, and energy dense batteries seek out huge surface areas, in spongy forms of material, so they are fractal surfaces, with acres of surface all folded up into tiny spaces, and all electrically connected together by low resistance conducting paths.
Battery engineers, have shown great ingenuity, in constantly increasing the capacity, of common cell types, by novel construction methods.
But advances in that area come slowly and laboriously. And of course, they also want to reduce the cost of fabricating such ingenious structures. So progress is slow.
Don’t expect to hear of a new Mark Zuckerberg of batterydom, any time soon.
I’m actually a physicist mathematician, with a long engineering career in electronics, and optics.
I’ve got a few hat feathers, I’m sorta proud of.
[A few hat feathers are nothing to sneeze at …. 8<) Mod]
Huh the electric car lost to the internal combustion engine, before that it was barely competing with the steam car and horse.
Electric cars are cheap and common in North America, we call them golf carts. However traffic regulations usually prevent their use in cities. Where they would do the most good.
A Quebec company was converting Renault Daphines to electric, Transport Canada finished their dreams off, what is not permitted is forbidden.
Who ever builds a battery competitive with a tank of gasoline will be a billionaire. But as a higher capacity battery is a bomb, the safety regulators will ensure the inventor will die penniless and bemused.
Jake J,
“I’m not a car marketing specialist, but when there are 35% of households with two cars and 20% with three or more, I think some of ‘em are buying or leasing new second cars. ”
The vast majority of those two care households are couples where both work. Both fully use their own cars. The three car households are also two income households, but add in a teen driver. Not many of these households would be looking for what an electric car can provide, at least not without the electric being significantly less expensive up front than a gas car.
If that’s the market being targeted, the EV needs to be < $15K
george e. smith, interesting stuff. What I don’t know about batteries fills books. What about this? Put aside the specific numbers, and figure they’re engaging in grantsmanship. What about the concept?
http://www.extremetech.com/computing/153614-new-lithium-ion-battery-design-thats-2000-times-more-powerful-recharges-1000-times-faster
Got any opinion about M.I.T.’s liquid metal battery? I for one am astonished that someone would fine $500/kWh attractive. Even now, lithium-ion car batteries are cheaper than that. And please ignore the hype in the article about Tesla and about pumped storage. That stuff drives me a little nuts, I being very, very far from being a member of the Cult of Elon.
http://www.bloomberg.com/news/2014-03-06/mit-s-liquid-metal-stores-solar-power-until-after-sundown.html
The vast majority of those two care households are couples where both work. Both fully use their own cars. The three car households are also two income households, but add in a teen driver. Not many of these households would be looking for what an electric car can provide, at least not without the electric being significantly less expensive up front than a gas car.
If that’s the market being targeted, the EV needs to be < $15K
You’re a lot more doubtful about this particular market than I am. We’re going to get an opportunity to find out pretty soon. Even at today’s numbers, a Nissan LEAF’s $200/month lease sets ownership cost about $15/month higher than for a gas Versa. That’s awfully close to parity. Double the LEAF’s range and keep that lease nut within reason, and I think we’ll see a big sales expansion.