Energy from High-Altitude Kites 288
maddmike writes "High altitude kites could produce energy equal to some power stations at a comparable cost without polluting. The technique uses a thing dubbed a 'Laddermill' - a chain of kites attached together to create a loop in the sky more than 5 miles long."
Re:how? why? (Score:2, Informative)
Re:Air Hazzard. (Score:4, Informative)
The Laddermill would only be flown where aircraft are banned. One such area is the zone along the US-Mexican border, where high-flying balloons fitted with radar are used to combat drug traffickers.
It's not even slashdotted. Yet.
Re:how? why? (Score:3, Informative)
It differs from regular windmills in that you should have read the article.
Difficult but could be promising (Score:5, Informative)
The former problem is essentially a strength vs. weight problem that even high tensile lines made of dyneema won't solve easily (above 400/500m, a 6m parafoil can very well sit there and refuse to climb with standard lines).
The latter problem introduces a problem of angle, since the line becomes curved under the wind drag, which makes the section right under the kite more and more vertical as it climbs, which in turn "flattens" its incidence angle and reduces its lift. It's always possible to modify the incidence on the ground to compensate, but takeoff can get dicey then. And of course, the wind drag on the line also tends to pull the kite down, and it's not negligible with a lot of line up.
So yes, it should be possible to use kites to generate power, but there will have to be a great deal of electronic magic to regulate everything, down on the ground and up in the air, if high altitude flying is to be more than stunts performed by enthusiasts on good days with (semi-)controlled conditions.
Links for the lazy (Score:5, Informative)
Re:Feasable? (Score:3, Informative)
Re:Ben Franklin (Score:2, Informative)
Trains beat single kites (Score:5, Informative)
The record, set back in 1969, is 10,830 m abg. So the 30,000 ft mark has already been surpassed.
The single kite record stands at around 13K feet.
Can't see the wood for the trees... (Score:5, Informative)
Have a look at some of the plans and protoype pics of this behemoth, and it becomes clear (if not in the article) that the intention is for the ladder to be ground-originated, not just ground-anchored. This means the kites are travelling up from the ground to 5 miles and back again. The volume occupied by such a structure - especially one as non-static as this - would be monumental, not to mention the massive safety margin required to have more than one in operation within a few miles of any other ladder.
So if we're looking at 400 ladders to generate enough to power a city, we're look at a good 3000+ square miles of land if we're to be sure that no ladder is to collide with another. Not practical on any scale, I suspect.
Now if we're to be sure the things don't come down every time there's a spot of bad weather, we are looking at getting them up above the common cloud-cover atmospheric strata. In that case, why the hell not just use bigger kites, no ridiculous ladder-arrangement, and use the kite-wing surface-area to convert solar-energy? If the kites are well-engineered and -controlled enough to be able to operate in such a stringently unified fashion, I'm sure the same technology could be used to keep solar-kites in the air. True, the strain on the cables would be even greater if they have to be reliable electrical conduits as well, but that's really only one of several major flaws in this project.
Frankly, we'd be better off burning drug-addled research-scientists as fuel. They're renewable, at least.
Re:Article skimpy on details ( as usual ) (Score:5, Informative)
Side note. Kinda funny how it is being developed for high altitude in the Netherlands.
Official Website (Score:3, Informative)
http://www.laddermill.com/
or, for that matter, do a Google search for "laddermill":
http://www.google.com/search?q=laddermill
Now how hard was that?
Re:Feasable? (Score:5, Informative)
Lots of possible problems. (Score:3, Informative)
As far as the balloons on the border, here is an example from the descriptions on the appropriate aeronautical charts (referring to the few balloons on the border) -
CAUTION UNMARKED BALLOON AND CABLE TO 15000 FEET IN R-6317
The entries for the few other sites list alitudes of 14000 or 15000 feet. The chart doesn't say that aircraft are banned, but most pilots would avoid flying around the balloons just to be safe. In any case, it probably isn't a good idea to put kites on a cable in the same place as balloons on a cable, due to the risk of becoming entangled.
My personal guess is that the FAA will shoot this project down well before it gets off of the ground, unless the kites are equipped with transponders (since they will be in CLASS A* airspace) and lights (so that pilots flying VFR can see and avoid).
* For those without an aviation background, all aircraft in CLASS A airspace are required to fly instrument rules, have transponders, and are controlled by controllers on the ground. In the US, Class A airspace is all airspace between FL180 (about 18,000 feet) and FL600 (about 60,000 feet).
This idea is not new (Score:4, Informative)
The idea of tethered high altitude wind power generation has been around for a long time. The people behind Sky Wind Power Corporation (http://skywindpower.com [skywindpower.com]) have been developing their technology since 1979.
They do not use kites but a tethered electrical generator, like a helicopter with 2 fifteen foot rotors and no cabin. The documentation on their site seems to cover a lot of questions that would come up here, especially about the tether etc.
It is just sad to see another australian inventor having to go overseas to try and get their idea noticed.
Re:Five miles high (Score:3, Informative)
There is a good picture at http://www.ockels.nl/Introduction.htm [ockels.nl] (from http://www.laddermill.com/ [laddermill.com], which somebody else posted).
Re:High altitude == better efficiency (Score:2, Informative)
Drawing of the system [laddermill.com]
Re:The numbers don't add up... (Score:3, Informative)
Yup. (Score:2, Informative)
The power is generated by the action of wind on the kite producing lift on half of the loop, and through manipulation of control surfaces, subsequent down-force on the other side of the loop. It's the mechanical conversion of wind-power that is harnessed here, so the simple lift generated by a blimp wouldn't work - how does it go down after it's ascent?
However, I think you'd be correct in another regard - having the kites anchored to a floating point (for example a blimp) would allow for a much more efficient system since the kites wouldn't have to go through thousands of feet of significantly slower wind each cycle. There's hope yet...
Re:Tension must be horrendous (Score:2, Informative)
As long as each kite in the stack is capable of lifting its own weight plus the weight of the cable to the next kite in the stack, the "tension" on all of the pieces of cable will not necessarily accumulate from segment to segment. As long as it's engineered correctly, they could use strong fishing line as the cable (although that probably wouldn't handle the wear of going through the electrical generator ground station).
The overall tension will be whatever is needed to maintain the kites going up one side of the loop and coming down the other.
As far as safety is concerned, if you read more about their thoughts at www.laddermill.com, their ultimate intention is to make each "kite" a computer-controlled wing (complete with GPS). If the cables snap, the wings could control their glides down.
Re:Superficially, this sounds like crackpot (Score:3, Informative)
What, never heard of biogas?