![Altaeros_Wind_Turbine_Wide[1]](https://wattsupwiththat.files.wordpress.com/2014/08/altaeros_wind_turbine_wide1.jpg?quality=83)
From NCAR, some wind pie in the sky.
A mother lode of wind power
Mapping the potential to harvest high-altitude wind
May 28, 2014 | What if all the energy needed by society existed just a mile or two above our heads? That’s the question raised by researchers in an emerging field known as airborne wind energy, which envisions using devices that might look like parachutes or gliders to capture electricity from the strong, steady winds that blow well above the surface in certain regions.
While logistical challenges and environmental questions remain, scientists at NCAR, the University of Delaware, and the energy firm DNV GL have begun examining where the strongest winds are and how much electricity they might be able to generate.
Their key finding: winds that blow from the surface to a height of 3,000 meters (nearly 10,000 feet) appear to offer the potential to generate more than 7.5 terawatts—more than triple the average global electricity demand of 2.4 terawatts (as of 2012, according to the study). Among the areas where such winds are strongest: the U.S. Great Plains, coastal regions along the Horn of Africa, and large stretches of the tropical oceans.
This type of research could prove critical if airborne wind energy takes off. The growing industry now includes more than 20 startups worldwide, exploring various designs for devices that could be tethered to ground stations and then raised or lowered to capture the most suitable winds at any point in time.
“From an engineering point of view, this is really complicated,” said NCAR scientist Luca Delle Monache, a co-author of a new study examining these issues. “But it could greatly increase the use of renewable energy and move the U.S. toward the goal of energy independence.”
To estimate the potential of airborne wind energy, Delle Monache, with Cristina Archer at the University of Delaware and Daran Rife at DNV GL, turned to an NCAR data set known as Climate Four Dimensional Data Assimilation. It blends computer modeling and measurements to create a retrospective analysis of the hourly, three-dimensional global atmosphere for the years 1985–2005.
The research team looked for various types of wind speed maxima, including recurring features known as low-level jets. Such jets can be ideal for energy because their speed and density is as high or higher than jets at higher elevations that would be beyond the reach of tethered wind devices. They also blow more steadily than winds captured by conventional wind turbines near the surface, potentially offering a more reliable source of energy.
Low-level jets blowing at 30-50 miles per hour or more can be found at several locations worldwide, often close to mountainous terrain or to persistent atmospheric features that help focus and channel wind. One of the strongest low-level jets on Earth flows from the Gulf of Mexico north across the Great Plains.
A study by the scientists, published last month in Renewable Energy, focused on winds in January and July. The team is now looking for additional funding to provide a more complete picture of the potential of higher-level winds. Their main goals are to estimate the strength of the winds year round and to build an interface that would enable users to explore the strength of the winds over specific regions.
“It’s important to understand the magnitude of this resource and what might be possible,” Delle Monache said.
Just a thought…. is there any way the generator could be moved to the ground?
Say a long loop of cable, turned by the wind rotors at the top, turning a generator on the ground.
This would get rid of the need to have the generator or power cables in the air at all, a balloon with lightweight rotor could be very light.
The only immediate sticking block I can see would be slack in the cable loop (such as when your fan belt gets loose in a car) but I’m sure that could be overcome with some sort of notched or holed cable.
Just a thought…
When I was a lad I owned a wind up toy car – now, if only we could upscale that? The only problem is how do we turn the key?
Jim G says:
August 14, 2014 at 11:27 am
Why not just land some fusion generators on the Sun and beam the energy down to Earth? You’re thinking we cannot land on the Sun, but maybe we could go at night.
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I don’t understand why you’re not already in charge of our energy policy!
You can’t beat burning wood for energy then regrowing trees from sunlight. Zero waste!
Wood energy all the way!
Sounds like this power source gives you a woody……
Old fella . . . right idea but depth might prove to be a problem . . . here in the seas around Scotland we have an almighty amount of power awaiting to be tapped in the endless and regular flow of huge masses of water, much of it less than 200 feet deep. . yet so far there has no industrial exploitation of its massive potential – probably because of the masses of taxpayers’s money swilling about in the direction of useless wind turbines erected by the rich friends of those with political power . . Despite all of the expertise applied to extracting oil from around our waters there has been no serious transfer of interest into what could easily be the cheapest and most reliable energy source available to us here: HEP at sea. . There’s enough to power Europe if the right approach was used. . . . There has been discussion about how it should be done and the favoured solution is the installation of turbines similar to wind turbines on the sea bed . . . an utterly ridiculous proposition except that it will probably mean more money for the parasites who depend on taxpayer subsidy instead of real inventiveness and engineering brilliance, not much of which would be needed because all of the elements required have already been used to create oil rigs and HEP on rivers and Lochs . . . Real entrepreneurs are a bit thin on the ground over here . . .
Maybe Weather Underground and Penn State should have a talk with engineers on the subject. For any appreciable array of these things, two things would happen: you would slow these winds down and shift the breeze away from the array and you would shade the ground, robbing it of some of its sun’s energy. I’m sure there are other undesirable effects to consider as well – rainfall patterns maybe, etc.
Also, rather than floating heavy rotating machinery up into the air, build a huge penstock and pipe the breeze down to surface or underground turbines.
For the future, it’ll mean that we have to expect not only chopped birds from wind mills but also chopped planes?
Aha, there’s a problem with your plan. That problem is that you can’t use a cable to make it work, it would have to be a hard shaft that would be very heavy and easy to break. Trying to spin the cable would cause it to just roll up on itself or rip itself asunder.
Either way, transferring mechanical energy over long distances is simply impractical
Obviously this con-game-scheme doesn’t come from any competent engineer. A 6-mile high pinwheel would at least be barely plausible (but stupid).
I take it that not too many folks here have ever flown a kite very high off the ground. The strength to weight ratio is about the only think that matters. As kids, we used to fly our kites on rope lay twisted cotton fishing line of about 8# test. Yes they broke.
Today’s solution without a doubt, is Gel spun Polyethylene, probably 8 pick braided. It is less dense than water (floats) and a typical line (for fishing) , is about 0.25 mm diameter, and breaks at around 70 pounds tension. It has virtually no stretch, and that mostly due to the weave.
It is made into huge cables, perhaps a foot in diameter, for towing barges. It is hydrophobic, so doesn’t pick up weight in the rain or the ocean.
Spectra is the formal trade name. Sailors use it for light high strength lines. Maybe mountaineers use it for climbing ropes.
Carbon nano ropes, will be along, in the market; just a tad after Fusion energy becomes common.
In any case regardless; (or irregardless, as the case may be), the string, will hang in a Catenary curve, which is either a Kat-en-airy, or a Kit-een-uh-ree, with accent, on the first and second syllable respectively. I use the first option.
The GG Bridge cables are NOT catenaric, because of the roughly horizontally uniform loading of the roadway, via the vertical dangles.
But back to the kite. Eventually, no matter how long a string you have, the kite will never go above some limit height. It will simply move further down wind, and the line at the ground, will be virtually horizontal; think GGB, so the kite string always ends up in the trees, 300 meters down the street, over a neighbor’s fence. So fly your kites over the water.
Dumb idea IMHO.
Mac the Knife says:
August 14, 2014 at 11:52 am
This is the same airspace that most of private aviation and a lot of regional commercial aviation use for cruising altitudes, around the world. All aircraft take-offs and landings (commercial and private aviation) use this airspace. The tether cables for this energy kiting scheme would be lethal hazards for all aviation. Think about that, the next time you board a plane…..
Not, not a problem. They’d just designate a restricted airspace below QNH-Baro transition altitude and unrestricted above. That’s between 10 k to 11 k ft in Oz, and a bit higher (if I remember correctly) for North America.
The real problem is having the airspace area available to designate a new restricted block in the first place. The congestion is terrible already in most small countries (drones have just made it worse as well) and you need about a five mile buffer around the R-border. But places like Canada, Australia and parts of Africa could deploy them. Maybe some Eastern and northern European countries could as well. If they were extra cheap and efficient airspace regulators would re-organize national airspace boundaries to accommodate them.
milodonharlani says:
August 14, 2014 at 11:45 am
…
Maybe housing the next three billion people before population stabilizes.
You’re off by about a factor of 5. The only UN Population Survey “band” (spreadsheet) that’s ever been even close is the Low Fertility one. It now predicts ~8bn by about 2045, declining thereafter (6,xxx,xxx by 2100). Population decline may require perfection of androids to make up the work force.
typo: 6,xxx,xxx,xxx by 2100
My children, when much younger, had a book with a collection of trivia. I have recently seen this word picture on the web.
All 7E9 people on earth today would fit easily inside the boundaries of the Grand Canyon with room for twice to three times more. All it takes is a simple calculator to verify this.
Allow a 3′ by 3′ by 6′ space for each person, 54 cu ft. A triangular section a mile wide, mile deep, mile long would hold about 1.4E9 persons. Five miles would handle that. If they all curled up fetal like, 2′ by 2′ by 3′, 12 cu ft. 6.1E9 people, so a little over a mile.
Been to IKEA? They have a display of about 400 square feet that they furnish with their products to illustrate a small apartment. If you allocated 400 sq ft to every one of those 7E9 people they would fit inside the state boundaries of Colorado.
Ponder on that image. Every single human being inside the Grand Canyon. Not one human anywhere else on the face of the earth.
7E9 is big number, but the number by itself can not represent any kind of problem.
So what’s the real problem? Poverty? Disease? Wars? Hunger? The first step in a solution is describing the correct problem.
Dr. Strangelove says:
August 15, 2014 at 12:11 am
Sorry wrong calculation. The steel cable only weighs 60 tons. So the balloon is not too big. The engineering can be solved. The problem is cost. The power generated is little more than land-based turbine as it is a function of turbine size and wind speed. But a lot more expensive to put the turbine in a balloon with 3.5 km long cable.
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That’s exactly the radius required to avoid the mutual entanglement of the wiring. And it is a safety zone of approx. 40 km^2 required, getting a 60-ton cable on the head isn’t funny, I presume. Now see how many solar panels a greedy rent-seeker can put on that area…
So, this idea should go from the drawing-board directly to the dustbin.
People who are dubious of the technical, engineering and operating challenges of this I’d just say I’d rather a $Trillion was poured into getting this technology up, than pouring it into a too-big-to-fail but failing nonetheless, bank, or even into fusion research, because if they crack this, and it can be scaled to compete economically with coal, we will be home and hosed for baseload energy for a billion years, at least.
That’s a pretty solid investment yield.
In Holland we had Wubbo Ockels, our first astronaut, promoting kite energy. In this system the ground-based generators are intermittently rotated by the pull of the kites.
The technical minutia of this idea can be nit-picked all day long. Reminds me of those futuristic articles in 60’s era Popular Science magazines at my grandfather’s house.
Back to the basics.
What problem does this “solution” solve? Carbon free electricity? That’s a bogus problem so you can expect bogus solutions.
Dr. Strangelove
Your correction is accurate.
Check out this table for steel cable
http://www.engineeringtoolbox.com/wire-rope-strength-d_1518.html
for 2″ (52) mm cable the weight per meter id 10 kg
For 3000 meters, the weight is 30,000 kg
The safe operating load is 285,000 Newtons. You cannot go to tensile strength
Therefore the steel cable can be 3000 Meters long unless other loads which cause tensile in the cable are significant. Some of the other loads are caused by wind loads on cable which may be significant for wind velocities at higher elevations,, extra balloon lift above actual weights to keep cable taught, conductor cable, instrumentation cables, etc
Every cable system with better strength to weight ratios will have a length limit,
nickreality65 says:
August 16, 2014 at 6:11 am
What problem does this “solution” solve? Carbon free electricity? That’s a bogus problem so you can expect bogus solutions.
True enough nick, the coal has a long way to go, and it is cheap. I don’t see its use going away. But it emits more than CO2, and soil and habit is destroyed in strip-mining, plus ancient mountain landscapes that are hundreds of millions of years old are being turned into plains and plateaus. It’s high impact and ugly. If much of that can limited or made unnecessary, I’m all for it. It does no one harm to support the development of a technology that could do the same thing as coal, with a lot fewer downsides.
In the end it will come down to cost, and it has to stand on its own economic merit, just on operational subsidies. That said, the national grid and coal power stations in oz were all originally built with public money, as were the rail networks from the mines for the most part, and only in recent years has all this been sold to the private sector. I sure don’t want them to do that with solar and wind mills as they’re not base load, and their economics are .. phft!
Should read: “… on its own economic merit, [not] just on operational subsidies.
RobL says:
August 14, 2014 at 8:35 pm
I’ve worked professionally on kite wind power. As someone who has actually analysed these systems there are lots of incorrect assertions above.
Couple of issues I see is that the bigger the balloon gets the more difficult it becomes to deal with weather, where alto cumulus can grow to a CB with powerful turbulence in under 5 minutes. It’s going to take time to get it down. So what do you do about the severe turbulence or hail hitting balloon fabric and lightning to earth? (which I expect will be very common)
Plus the bigger the balloon the more susceptible it becomes to windshear stresses. As pilots know this often comes in the form of dust devil type circulations (sans dust, so invisible rotating air) that can be longitudinally oriented in any direction from vertical to horizontal and any angle of inclination in between. In other words, there will be strong shear loads applied to the balloon structure. so what happens if several cells rip open, does it lose altitude gracefully in a repairable way (modular replaceable cells say), or will it come crashing down destroyed?
“The growing industry now includes more than 20 startups worldwide, exploring various designs for devices that could be tethered to ground stations and then raised or lowered to capture the most suitable winds at any point in time”
The above comment from the post displays the problem with government subsidized development of new energy sources. It suggests a fragmented research typical of the DOE distributing funds to numerous “friends” without an overall plan to conduct a simplified engineering study to evaluate feasibility and enumerate the obstacles and evaluate each obstacle to determine if each hurdle has a practical solution.
Wonder why so many of the subsidized ventures failed.
Can any one recite the list of DOE or other successful subsided projects have provided a significant amount of renewable energy? The failure list is long including Solyndra, Range Fuels, etc.
The US government has spent circa $150 billion dollars on Climate change in the last decade or so. What benefits have resulted from this expenditure besides global warming propaganda? . .
So why does carbon equal coal? Natural gas, propane, ethanol, wood all produce that evil carbon dioxide. Do people talking carbon free realize that means back before fire? That might take few social/economic adjustments.