Kite-driven generators have been suggested as one method of capturing this energy. In principle, they work by using the strong pull of the wind to drive a land-based turbine, tethered to the kite via a cable.
Credit: Sky Windpower Corporation
SYDNEY: High-flying Kites could harness enough energy to power the world 100 times over, according to a survey of high-altitude winds.
Published in the journal Energies, the study reports that areas well suited to harvesting high altitude winds fall over some of the world's major cities such as New York and Tokyo.
"The wind energy aloft is phenomenal. Energy densities unthinkable near the ground are common in the upper levels of the atmosphere," said Cristina Archer, lead author and a meteorologist at California State University in Chico, USA. "It's like a perpetual source of free energy."
Fast and furious
"These winds blow much more strongly and steadily than near-surface winds, but you need to go get up miles to get a big advantage. Ideally, you would like to be up near the jet streams, around 30,000 feet," added coauthor Ken Caldeira, a climate scientist at the Carnegie Institution's Department of Global Ecology in Stanford, California.
Jet streams are moving belts of furious winds, shifting seasonally at altitudes between 6,000 and 15,000 metres. To get a global picture of the energy these jets hold, the researchers compiled 28-years-worth of data from both the U.S. National Centres for Environmental Prediction and the Department of Energy.
Archer and Caldeira looked at both wind speed and air density at different altitudes, concluding that extraordinary amounts of energy exist above Japan, eastern China, the eastern coast of the U.S., southern Australia and north-eastern Africa.
Kite-driven generators
Average wind power densities in these locales "are greater than 10 kilowatts per square metre. This is unthinkable near the ground, where even the best locations have usually less than one kilowatt per square metre," said Archer. New York clocked up a whopping wind power density of 16 kilowatts per square metre, the study found.
Kite-driven generators have been suggested as one method of capturing this energy. In principle, they work by using the strong pull of the wind to drive a land-based turbine, tethered to the kite via a cable.
When the cable reaches its full extension, the angle of the kite is shifted so that the wind no longer pulls and the cable can be rolled in again, before the cycle repeats. A prototype kite designed by Dutch former astronaut Wubbo Ockels, now at the Delft University of Technology in the Netherlands, was able to generate 10 kilowatts of power - or enough electricity to supply 10 homes.
flying a kite !!
A fantastic idea,please don't let the politicians any where near it.
Insurance
When (not if) these kite power-generators fall, they can hit anywhere (hospitals, major highways, chemical plants, etc.) and so the potential liability to their manufacturers/operators is unlimited. No insurer would write a policy under that condition and companies can't operate uninsured. Kite-power companies will need national legislation to artificially limit their liability, as now exists in the U.S. for nuclear power plants. I don't see such legislation happening while existing power and fuel companies can lobby to prevent it.
Flying kites
A little experience in Vietnam where a barrage balloon was used to hold a radio set aloft indicates that a 5000 cu ft helium filled balloon was needed to hold the back-pack radio together with its tethering cable and a radio transmission cable - and that was only to 1000 metres height.
Can anyone tell me how much the cable would weigh for these very much larger flying kites? Think in kilo-tonnes.
Yes great idea; keep 'em coming!
Funny how we are all so skeptical about politians; will we ever get them to be serious about energy and being sensible about the Earth running out of limited resources? Capitalism does not work in the long term. The man in the street sees it but our short-sighted "leaders" trundle on with their old ideas. Patting each other on the back, dreaming they are being of use...I long for sense, but I can't see any real changes coming, unless, and this is ironic, it comes from the U.S.?
Let's Go Fly A Kite...
With a decent sky-hook pulley system, we could even generate power on the downwards trajectory (if only...).
But seriously, this is only the beginning of a potentially very exciting alternative source of energy. Kites could be tethered to each other to create massive 3-dimensional high-altitude lattices of wind energy generation, to avoid the necessity of having one massive cable for every kite.
As for the risk of failure, it is actually very, very low. It is easy to imagine that such kites would have few if any moving parts. Besides, devices exist to allow things to fall safely through the air without damaging themselves or others when they land in case of emergency - they're called parachutes.
This technology is exciting and entirely feasible.
yeah
Next, we'll show how to reconcile the chinese and the russians, how to split an atom, and how to irrigate vast areas of the sahara desert.