 | The Bullroarer - Sunday 13 January 2008 | TOD: Australia/New Zealand | The Bullroarer - Monday 14 January 2008 |  |
75 comments on Alternative Wind Power Experiments - SkySails and Airborne Wind Turbines
Comments can no longer be added to this story.
User login
Contact
- anz at theoildrum dot com
License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
Archives
GAIA Host Collective
I love these ideas, despite any shortcomings. It's an aesthetically cool way to power a civilization. Then again, I admit to a fondness for putting things up into the sky, which I've been doing since I was about 6. Being bored in the Indiana far-suburbs, my younger brothers and I made all manner of unlikely things.
Among these things was putting a small generator and fan blade beheath a 12-foot standard-design kite to power the flashlight bulbs on it. Worked until it broke. This would have been in about 1967, in the unlikely event nobody did it before... though we didn't run power down the wire. We did use wire once on a stable kite about 100m in altitude in a thunderstorm to see if we could direct a lightning bolt to some stuff on the ground we wanted to fuse together, but the results were ambiguous as we weren't nuts enough to stand at the base of it, and it was gone after the storm.
We also built enormous translucent hot-air things out of 10-cent plastic dropcloths stapled together, but these had to be "release and watch" devices with the occasional side-effect of sometimes dropping chunks of burning sterno on rooftops like blue napalm... a pretty effect, though, and the things looked like invading martian sandworms or something. But I digress....
Similarly, back in the 60's you could get large surplus military parachutes through mailorder ads in comic books, and we used these for motive power on a number of garage-made vehicles. These would not only propel a human at significant speeds downwind, but would actually go over any buildings in their way. We never did figure a way around the power-line drawback other than to use expendable passengers; and our test-pilot quit riding the things when he had to bail out 20 feet in the air when the 'rocket sled' headed over the Fall Creek School gymnasium. He was still on the rise when he hit the side of it. There was definitely power involved.
Later in life, I suggested kites for the Greenpeace vessel RW, but it was refitted with large fairly-conventional sails instead.
Tensile strength rocks for construction, and hanging things up in the wind to generate electicity is great. Dozens of ways spring to mind, and they should probably all be tried.
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.