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75 comments on Alternative Wind Power Experiments - SkySails and Airborne Wind Turbines
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Like greenish, I love these ideas.
How far can it go? I see one number of 10 to 15% fuel saving. Why not 99% as D111 suggests? I think the answer must depend on operating cost of bunker oil fuel relative to capital cost of the kites. If the idea succeeds at all, the percent saving will be determined by the drift of prices over time.
Also, I note in the Briza PDF they talk about placing their blimps in the wind shade of their wind turbines. This wind kite idea is the first idea that I've seen that has, I think, some chance of success. It makes me wonder what is the total size of the wind resource. There is wind shade for each one of these things. They must therefore be placed at some minimum spacing. All the different kite designs must have different minimum spacings. Has anyone seen serious engineering / scientific calculations of this resource?
As soon as you get above around 800 meters, 8 times the height of the tallest windmill, or 300 meters at sea, the wind power resource is both vast and reliable.
It contains many hundreds of times as much energy as is needed by, say, 15billion people in a technological society.
It is also one of the most concentrated forms of renewable energy, far more than solar.
Effectively, the only part of a windmill which generates power is the area towards the tips of the rotors, so all the rest of the structure, the base, and the tower and most of the blades, are not generating power.
Kites cut out all this waste.
If you look at the pdf's on the kitegen site I linked, much of what you wanted to know is there.
By sweeping the airspace above a nuclear plant, which is restricted anyway, a kitegen system is calculated to generate as much area as the plant!
The control system for the multiple kites on this system is probably the difficult bit.
You will find most of the rest here:
http://www.skywindpower.com/ww/index.htm
Makani looks to be going for a system where you have the generator on the kite, you power up using an electrical lead of high-performance materials, and fly it to the required altitude.
The propellers then stop being driven, and start collecting wind energy.
The kites would be larger than on the Kitegen system, and controls simpler.
If you think in terms of using around 1% of the airspace in the States, you are in the right ball-park.
The exact amounts depend on all sorts of variables, including the height that is chosen - winds get stronger as you go higher, but obviously affect air traffic control more.
High altitude wind is one of only two technologies I am aware of which might actually greatly reduce energy costs as against current levels, the other being mass-produced nuclear plants.
Hot rock Geothermal could provide a lot of power almost everywhere, but getting it is probably relatively espensive.