Kites could provide electricity for 100,000 homes

Aug 08, 2008 by Lisa Zyga weblog
Scientists from TU Delft have demonstrated that flying a 10-square-meter kite could generate 10 kilowatts of power, which could supply electricity for about 10 homes.

High-flying kites tethered to generators could supply as much as 100 megawatts of electricity, enough to power 100,000 homes, according to researchers from the Delft University of Technology in The Netherlands.

The scientists have recently demonstrated that flying a single 10-square-meter kite could produce 10 kilowatts of power, which could supply electricity for about 10 homes.

In their next experiment, the researchers plan to test a 50-kilowatt version, called Laddermill. Eventually, their goal is to build a multi-kite system that could generate a full 100 megawatts.

As project leader and professor of sustainable engineering Wubbo Ockels explains, kites generate power by pulling on their strings that are attached to generators on the ground. After reaching their maximum height, the kites are reeled back down to repeat the process.

Electricity produced by kites in the wind could be inexpensive, too. The researchers predict prices to be comparable with generating electricity using coal power, and half that of using wind turbines.

One advantage of kites is their potential height. Commercial windmills generally reach heights of around 80 meters, where the average wind speed is about 5 meters per second. At higher altitudes, such as 800 meters, the average wind speed is about 7 meters per second. Because the amount of power available from the wind is related to the cube of its speed, blades at higher altitudes could generate up to five times the amount of electricity as at lower altitudes. High-altitude wind is also generally more reliable than ground-level wind.

While building an 800-meter-tall windmill would be impractical, a kite can easily reach that height, and take advantage of the higher wind speeds. The Dutch scientists note that a high-speed jet stream makes countries such as the UK, The Netherlands, Ireland, and Denmark especially good locations for kites.

Using computer models, researchers can determine how to configure kites so that they get the most out of the wind. Ockels´ system used figure-eight flying patterns developed by Allister Furey of the University of Sussex, an arrangement that increases the speed of the air flowing over the kites. He´s also investigating a yo-yo configuration, where one kites goes up as another falls from the sky like a glider.

"Pretty much anywhere in the UK you could run a kite plant economically, but you couldn´t run a wind turbine economically," said Furey.

Several other scientists are investigating the use of kites to harness energy from the wind - which some researchers estimate provides more than 100 times the amount required to power the entire planet. In 2007, Google´s philanthropic arm invested about $10 million in a US kite company called Makani. An Italian company called Kitegen has a multi-kite scheme that could generate a gigawatt of power, as much as a standard coal plant.

via: The Guardian and EcoGeek

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ruebi
4 / 5 (1) Aug 08, 2008
couldnt strings of bouy(sp) do the same thing with ocean currents? could we eventually make solor kits as well?
DGBEACH
3 / 5 (14) Aug 08, 2008
I don't mean to insult anybody here, but wouldn't it require the same amount of energy to pull that kite back down that it gave on its way up? Or have they omitted the part where they change the kite's shape as they pull it back down...I like the idea and can see the advantages over fixed towers, but unless you decrease the drag on the kite on its way down this won't work.
Doug_Huffman
2.3 / 5 (6) Aug 08, 2008
"Pretty much anywhere in the UK ... you couldn´t run a wind turbine economically," said Furey.

Out of the mouth of a MENTALIST babe.
jaggspb
2 / 5 (2) Aug 08, 2008
I don't mean to insult anybody here, but wouldn't it require the same amount of energy to pull that kite back down that it gave on its way up? Or have they omitted the part where they change the kite's shape as they pull it back down...I like the idea and can see the advantages over fixed towers, but unless you decrease the drag on the kite on its way down this won't work.


Good point. I wonder if they could engineer the kite in a way to let gravity due the work of pulling it down at the desired time.
gmurphy
3.3 / 5 (7) Aug 08, 2008
"wouldn't it require the same amount of energy to pull that kite back down that it gave on its way up?"

Only if you kept the kite in the same state (catching air), it should be a trivial matter to built in articulated joints which reduce the surface area of the kite as it comes down.
nonoice
4 / 5 (3) Aug 08, 2008
Good point. I wonder if they could engineer the kite in a way to let gravity due the work of pulling it down at the desired time.

Trey are using a ai system to change the behaviour of the kite to descent autonomic. It changes the configuration of the kite and makes it a glider.
I went to a showcase here in Holland, The dude is like the only science celebrity we have.
jaggspb
2 / 5 (1) Aug 08, 2008
Trey are using a ai system to change the behaviour of the kite to descent autonomic. It changes the configuration of the kite and makes it a glider.
I went to a showcase here in Holland, The dude is like the only science celebrity we have.


Thanks for the info. I figured it would be a fairly feasible to do such a thing.

I wonder if he got the idea for generating electricity from them after someone told him to 'go fly a kite buddy'. ha
holoman
2.3 / 5 (9) Aug 08, 2008
Space-Based Microwave / Solar Power still the best solution for long term reliable / renewable energy.
jaggspb
2.2 / 5 (5) Aug 08, 2008
Space-Based Microwave / Solar Power still the best solution for long term reliable / renewable energy.


and the best solution to efficient popcorn as well
D666
3 / 5 (6) Aug 08, 2008
Space-Based Microwave / Solar Power still the best solution for long term reliable / renewable energy.


Actually, fusion power is. One slight problem, though... :-)

googleplex
3.5 / 5 (2) Aug 08, 2008
Great idea from the windmill nation.
I am thinking that the kite could have a string to spill air when you make it descend, like a parachute. This would also be used to adjust the lift and hence pull force as wind speed changed. Very useful in storming/gusty conditions.
Of course the project requires permission from the FAA/CAA/JAA for that altitude. There is also the issue of lightning/static arresters, or could that be an energy source too?
Sophos
1.8 / 5 (5) Aug 08, 2008
What are the long term consequences of disrupting wind flow (or ocean currents) ?
jet
3 / 5 (2) Aug 08, 2008
as to pulling it back down using same energy, had the same first thought my self but after a bit of thinking.. not a problem just have a control line to collapse the kites aerodynamics and it will fall, or "fly" it lower by changing the angle of attack.
vlam67
1 / 5 (1) Aug 08, 2008
With current materials available, they could have built a light-weight turbine-generator systems with the blades filled with He or H. With proper designs the lift will take the whole lot up to where desired and generating electricity and transfered down thru the anchoring/transmission cable, without this messy systems of reeling and such!
ShadowRam
3.8 / 5 (5) Aug 08, 2008
Interesting, but I can't see this as being feasible.

Different winds rain, Hail, Snow would/could collapse the kites. Relibility is huge in power supply.

Random collapses with dying winds...
The energy required to get them back up flying?

Not to mention flying hazards... at least windmills stay in one spot...

Multiple kites tangle together?

Too many factors.. Wish they'd spend more time, money, effort on more feasible studies..
DGBEACH
2.7 / 5 (7) Aug 08, 2008
...'had an evil thought....let's build a H-U-G-E coil around the planet (in space) and harness the inductive-current for usage back on earth, and turn this spinning ball into its own energy source! :)
Sean_W
1 / 5 (2) Aug 08, 2008
jet is right. I have read about this elsewhere and they change the angle of attack so the wind is no longer generating enough lift. It then sinks and they roll in the string until it is ready to angle into the wind again.
weewilly
3 / 5 (2) Aug 08, 2008
I am a skeptic here although I like the idea in essence. I'd be kind of afraid of conducting a lightning strike to ground going through the machinery connected to these kits. I can remember the power of the wind to lift heavy objects when I was a kid. I cannot conceive of a mechanical device that would turn a rotating piece of machinery fast enough to produce a steady current flow. Maybe as a DC source with a large storage system and inverters. ????
mattytheory
3.3 / 5 (4) Aug 08, 2008
What are the long term consequences of disrupting wind flow (or ocean currents) ?
- Sophos

I like how no one addressed this issue. Indeed, what are the long-term consequences? Maybe, for once, we will attempt to answer this question first before the hole we have dug for ourselves gets any deeper, and the walls start to cave in.
DoctorKnowledge
2.3 / 5 (3) Aug 08, 2008
Well, the environmental consequences might be, on the balance, good. Might be.

This is a solution that doesn't cause a net addition to the amount of heat generated by humanity. If global warming is causing more severe weather -- higher winds -- then harnessing the winds might actually be good. I can dream, can't I?
deatopmg
1 / 5 (1) Aug 08, 2008
So... NO energy is being generated when the kite is returning to starting position, nicht wahr?

therefore, multiple kite systems are required. Paired systems would be good then the ascending generator could take up the slack of the descending kite's cable. Other pairs could be operated at various phases to smooth out the power generation. BUT we'd still have to deal with the myriad of problems pointed out in the earlier posts.
googleplex
1 / 5 (1) Aug 08, 2008
The key point is that this kite idea has been demonstrated, i.e. done. Most other articles we read are stepping stone technology. This one has been proven to work by demonstration (QED).
It just needs upsizing.
regda
1 / 5 (1) Aug 08, 2008
It seems to me that one could maintain the same altitude for the kite while keeping the generator turning by utilizing a scheme of ratchets or other such devices.
conservo
1 / 5 (1) Aug 08, 2008
Is there a video showing how this works with just one kite?

I can imagine using two kites that alternate loft, with one pulling the other through a pulley for a set distance back and forth to turn the generator shaft, but one single kite by itself is hard to imagine continuous power generation.
nevereverever
2 / 5 (2) Aug 09, 2008
Since conductive wire must be used....this seems like a great idea to conduct lightning bolts to the ground...Duh?...Not just wind generated electricty.....what are you going to do when 100 million volts of lightning fries you generator wires?
El_Nexus
2.7 / 5 (3) Aug 09, 2008
I don't think conductive wire is necessary. I think the wire will be wound around a big spool thing. As the kite ascends, it will pull on the wire and cause the spool to spin as it plays out more wire. This is where the electricity is produced, not up at the kite itself.

I can see problems with more than one kite, though. The strings could easily get tangled.
MDean
1 / 5 (1) Aug 10, 2008
couldnt strings of bouy(sp) do the same thing with ocean currents? could we eventually make solor kits as well?
MDean
4 / 5 (1) Aug 10, 2008
couldnt strings of bouy(sp) do the same thing with ocean currents? could we eventually make solor kits as well?


Ruebi - They have done some work on tides and currents generating elec. One was a dam type construct that forced water through a small opening to spin turbines. It was built on a tidal area of a river. As the tide came in the turbines spin one way, on the way out, the other. There were others. On this one, one here and there would be okay, but I'm not sure large areas covered with these would be a good idea.
David_M
3.7 / 5 (3) Aug 10, 2008
I see two problems with this design which render it more or less useless:

1) Winding the kite back to Earth requires the same energy generated from raising it, assuming constant wind speeds.

2) What happens when there's no wind? The kites fall to the ground. How would the relaunching of the kites be managed when the wind picks up again?

100,000 homes? That makes me smile.
Valentiinro
2.3 / 5 (3) Aug 10, 2008
It seems like some of the posters are thinking the kites will be holding up little windmills at altitude and some of the posters are thinking the kite will generate power as it goes higher, the kite being attached to a generator itself.

As for there being no wind at times, at higher altitudes there's just about always wind, which was the point. One needn't lower the kite all the way to the ground every time, especially if you have multiple kites on the same string. You wouldn't even need any AI system to control the rise and fall, you could have an analog system that when you run out of rope, it tugs on the kites "collapse" or "spill air" toggle.

As for lightening... If none of the parts were made of conducting materials then it might not be a big deal, but you could also have kites with metal bits and conducting string near your other kites, not connected to a generator but just acting as a kilometer long lightening rod. If someone did think of a feasible way to capture all that power, then you could convert all the lightening rod kites in the kite power stations (assuming this kite power thing takes off and some time later someone develops a lightening rod power system) to power generators too.
DGBEACH
1.3 / 5 (3) Aug 10, 2008
Lightning occurs when built-up static electricity in the clouds finds a quick route to ground, n'est-ce pas? But if you have constantly grounded conductors always present within or nearby those clouds then the static electricity will not have a chance to build up to high-voltage levels (required for arcing) and thus lightning will not occur (or would occur at a lower intensity)
In my opinion you'd want those cables to be conductive, and well grounded.
deepsand
1 / 5 (6) Aug 10, 2008
...'had an evil thought....let's build a H-U-G-E coil around the planet (in space) and harness the inductive-current for usage back on earth, and turn this spinning ball into its own energy source! :)

You do realize, I hope, that such would result in the spinning ball's rate of spin decreasing steadily.
Ulg
1 / 5 (1) Aug 10, 2008
I see two problems with this design which render it more or less useless:

1) Winding the kite back to Earth requires the same energy generated from raising it, assuming constant wind speeds.

2) What happens when there's no wind? The kites fall to the ground. How would the relaunching of the kites be managed when the wind picks up again?

100,000 homes? That makes me smile.


1. Only if the kite always has the same amount of lift the entire time the kite is up in the air, a controller string to operate a lift valve covers that. As mentioned earlier in this thread "like a parachute"

2. This is high altitude, if you go into a skyscraper there is never a day there is not wind hitting it- and these kites go much higher, up into the jet streams which really are constant and very powerfull.

EarthScientist
1 / 5 (4) Aug 11, 2008
Oh My boys,quite an array of garbage to determine the wholeness of a kite,oh my.

Just a tower on the nodes can provide the juice you seek,but old papa here cant allow that ,cuz the magma needs its peak, or a snowmobile suit you will seek. The magma needs its juice,but light energy will provide your juice. Its gonna take some time,before you get the rhyme.

KBetts
1 / 5 (1) Aug 11, 2008
One way to do this is to have the kite's line attached to a large drum that turns slowly. Then use some gearing (overload gearing) to increase the speed going to the turning generator. This is how Seiko designs its Kinetic line of wristwatches. Then have a radio control device to dump lift and a small motor to reel in the line, and repeat.
mgeo
1 / 5 (1) Aug 11, 2008
Agree it is a lot easier to use H, He or vacuum. Easier still to require skyscrapers to install windmill generators by law.
DGBEACH
1 / 5 (1) Aug 11, 2008
You do realize, I hope, that such would result in the spinning ball's rate of spin decreasing steadily.


So tell me how THAT would be more destructive than what we're doing to the planet now...once stopped;

-one side of the planet would constantly have daylight, which would reduce heating and lighting needs for a whole half of the planet (lets make it ours)
-without the spin, the jet stream would be stopped, so hurricanes and typhoons would be a thing of the past

...I DID say that it was an EVIL thought! :)

googleplex
1 / 5 (1) Aug 12, 2008
Here is a video of the demo generating power.
It appears electric power is generated as the kite moves around an irregular orbit. I could not figure out how the generator works but perhaps someone else could watch and tell me.
http://www.youtub...ctDA9IBU
googleplex
3.7 / 5 (3) Aug 12, 2008
Description:

There is an enormous amount of energy hidden in the winds over our heads. At an altitude of 30.000 feet, the wind energy is twenty times as large as at sea level. The laddermill is a new and novel idea to harness this immense energy resource.

The laddermill consists of a large number of kites on an upward and downward motion. The kites used are of a breed between regular kites and airplanes. Whereas a kite climbs relatively easy, getting a kite down requires a force pulling in the cable. An airplane, on the other hand, requires large engines to gain altitude. Decreasing altitude is much easier, as the aircraft can glide to the ground. The kites used in the laddermill, generally called "kiteplanes", combine the ascension characteristics of kites with the descension characteristics of aircraft. By creating a large loop of kiteplanes ascending and descending, a rotation can be created. In turn, this rotation can be coupled to a generator to create energy. The loop of kiteplanes can ultimately go up to 30.000 feet, which would generate approximately 100MW. The cable is an important part of the system and consists of strong fiber materials such as Dyneema. The kiteplanes themselves need to be both large in surface area as well as light in construction weight. Structural principles such as inflatables are being investigated. The control of the kiteplanes can be done by a pressure differential in the inflatable members. Its control will ultimately be automated using flight computers.
dritter
4.7 / 5 (3) Aug 12, 2008
After reading these comments it seems most people only feel kites provide power when they are "up high". If you have ever flown a "stunt kite" you would know this is not the case.

The kites proposed here are "power kites" they generate lift when they "move" through the air. This lift can be controlled by the position of the kite in the sky relative to the anchor point.

These kites are steerable and they generate tremendous lift depending of their speed and angle of attack relative to the wind. This is not exactly like a sail attached to a boat.

dritter
4.7 / 5 (3) Aug 12, 2008
What are the long term consequences of disrupting wind flow (or ocean currents) ?
- Sophos

I like how no one addressed this issue. Indeed, what are the long-term consequences? Maybe, for once, we will attempt to answer this question first before the hole we have dug for ourselves gets any deeper, and the walls start to cave in.


The Earth is not a featureless sphere. Mountains, trees and general surface friction are a far greater obstacle to wind than anything we could do with kites.

DGBEACH
3 / 5 (2) Aug 13, 2008
There is an enormous amount of energy hidden in the winds over our heads. At an altitude of 30.000 feet, the wind energy is twenty times as large as at sea level


It seems to me that most of the wind energy will be needed just to suspend those extremely heavy steel cables that high...it would make more sense to build one HUGE tower, filled with wind turbines, all the way up, 30,000 feet high (although I suspect that it wouldn't need to be anywhere near that height!) It could be located near big cities where the demand is greatest. 'Not sure of how much noise something like this would make...probably quite a bit!
googleplex
3.5 / 5 (2) Aug 13, 2008
There is an enormous amount of energy hidden in the winds over our heads. At an altitude of 30.000 feet, the wind energy is twenty times as large as at sea level


It seems to me that most of the wind energy will be needed just to suspend those extremely heavy steel cables that high...it would make more sense to build one HUGE tower, filled with wind turbines, all the way up, 30,000 feet high (although I suspect that it wouldn't need to be anywhere near that height!) It could be located near big cities where the demand is greatest. 'Not sure of how much noise something like this would make...probably quite a bit!


Quote from Wikipedia...

Dyneema and Spectra are gel spun through a spinneret to form oriented-strand synthetic fibers of UHMWPE, which have yield strengths as high as 2.4 GPa and density as low as 0.97 kg/l (for Dyneema SK75)[5]. High strength steels have comparable yield strengths, and low carbon steels have yield strengths much lower (around 0.5 GPA). Since steel has a density approximately equal to 7.8 kg/l, this gives strength/weight ratios for these materials in a range from 10 to 100 times higher than for steel. Strength to weight ratios for Dyneema are about 40% higher than for Aramid.
General_Haberdashery
3 / 5 (2) Aug 14, 2008
Wouldn't fluctuations in air current allow this design to work?

http://img139.ima...3hd8.jpg

Yay mspaint!
DGBEACH
1 / 5 (2) Aug 15, 2008
Nice drawing! LMAO
GrayMouser
1 / 5 (1) Sep 14, 2008
as to pulling it back down using same energy, had the same first thought my self but after a bit of thinking.. not a problem just have a control line to collapse the kites aerodynamics and it will fall, or "fly" it lower by changing the angle of attack.


You still have wind up all the line that was pulled out by the wind. This would require the same amount of energy as was produced by the kite pulling the line out.

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