Kite for generating clean power

[4world]

Was wanting to make an autonomous kite flight control unit that could be used to also generate power.

I have done a lot of searching but could not find anything that would directly suit this application. Could someone help please?

I need to mount sensors on the kite to transmit the following to ground control:
* Attitude (3 axis)
* GPS (3 axis)
* Air speed
* Voltage (in the range of 5 to 15VDC)

Need the attitude data sent at 10Hz or higher rate to control kite flight.

Need a low power system since I want to send power through the two steel cables flying the kite.

Can operate on 900MHz or 2.4GHz public band.

Just a 3-axis accelerometer may not give complete kite orientation info (I think?).

Attopilot might transmit the above data but don't know for sure. Of course it has the UAV controller that I wouldn't need.


I prefer a ready made solution even in the $1000 range.

Thank you for your help.

[zlite]

http://www.makanipower.com/home.html

[jglenn]

There is going to be a windmill on the kite? How will it generate power?

Since it is tethered and not free flight, the control system should be simpler,
I would think.

[Tom Harper]

4world,

The earth's electrostatic field is ~180 volts per meter agl (see experiment by Ben Franklin and C. L. Stong, "Electrostatic motors are powered by electric field of the Earth". Scientific American October, 1974.). 100 M would drive 18Kv down the cable. Flying with a kite with a steel wire can be hazardous to your health.

Tom

[jglenn]

Hmm, reminds me of the nasa power generating tether satellite, but that
was only a couple amps, and used the magnetic field I think. Hope you can get more current than that. It
might have to be transformed. Dc/dc conv. Hire Ben Franklin! ;)

[4world]

http://www.makanipower.com/home.html

Chris, Thanks for the link. That's a mighty team aiming *for-profit* (so they may not share any of their 'secrets' with us :( ). I am working in a small *nonprofit* team to provide a simpler inexpensive solution where low power (~10kW) is sufficient -- could do wonders in villages in certain countries in Africa and Asia.


4world,

Flying with a kite with a steel wire can be hazardous to your health.

Tom

Tom, Thanks for the heads up! I was already very concerned and so was going to use properly earthed cables. Wanted a solution for a melt-down capacitor between the two cables too (which I haven't found yet) since both would have a voltage across them and can't be simultaneously earthed.

--------------
The kite would generate power while unwinding due to the force of the wind. Once at the end of the cable, we would rewind after putting the kite into a 'depowered' state requiring less energy to bring it back. Then repeat the process.

*** Can anyone provide leads on where to get sensors and radio modems to mount on kite?

Thanks!

[airmcn_3]

Chris, Thanks for the link. That's a mighty team aiming *for-profit* (so they may not share any of their 'secrets' with us :( ). I am working in a small *nonprofit* team to provide a simpler inexpensive solution where low power (~10kW) is sufficient -- could do wonders in villages in certain countries in Africa and Asia.




Tom, Thanks for the heads up! I was already very concerned and so was going to use properly earthed cables. Wanted a solution for a melt-down capacitor between the two cables too (which I haven't found yet) since both would have a voltage across them and can't be simultaneously earthed.

--------------
The kite would generate power while unwinding due to the force of the wind. Once at the end of the cable, we would rewind after putting the kite into a 'depowered' state requiring less energy to bring it back. Then repeat the process.

*** Can anyone provide leads on where to get sensors and radio modems to mount on kite?

Thanks!


Depends on what kind of sensors and I would go with the X-Bee pro sysytem for modem. Its very small...

Check out Sparkfun for parts.

[4world]

Thanks airmcn_3.

Depends on what kind of sensors

Need:
* Air speed
* Altitude
* Kite orientation (all 3 axis)
* GPS x-y coordinates
* Voltage

I wonder if there is an all-integrated sensor module that would do all or most of the above.??

Thanks

[dmgoedde]

I am working in a small *nonprofit* team to provide a simpler inexpensive solution where low power (~10kW) is sufficient --------------
The kite would generate power while unwinding due to the force of the wind. Once at the end of the cable, we would rewind after putting the kite into a 'depowered' state requiring less energy to bring it back. Then repeat the process.Wow!! 10 kW and you call that small? I agree that 10 kW is small if you want to power a few houses, but not at all small if you are trying to gain this from a kite.

1) How big is this kite going to be?
2) will it go into a collapsed low-drag state for the time it's hauled back down? Otherwise you'll burn all the created energy just getting it back down.

A reality check via a little napkin physics: energy = Force * distance. To get units of power divide both sides by time: Power = (Force*Distance)/Time. Newtons and Meters and Seconds give answer in Watts.

Assuming the kite can't go much faster up than the wind velocity and a reasonable wind is 15 mph (6.7 m/s) this means you'll need a kite to create 1492 Newtons of force on the winch... that is 340 Lbs, and also assuming 100% efficiency.

I wish the best of luck to you. I would love to read your version of physical estimations that you think can achieve the 10 kW goal. How big of a kite, how far to let it go up, method to get it back down without burning all the energy you just made, etc...

[jglenn]

I am still not clear on how it will generate power. At first electrostatics
was mentioned. Now it seems the force on the string will do some work, don't
see how that will work.

In Popular Science a while ago was a design of a long string of small windmill rotors between 2 balloons I think. Or one balloon, tied to the ground. Really a long string, dozens of rotors. That might be more viable.

[4world]

1) How big is this kite going to be?10 to 12 sq. m. area. Planning to use the common 'Power Kites' that are used with water and ski surfing.

2) will it go into a collapsed low-drag state for the time it's hauled back down? Otherwise you'll burn all the created energy just getting it back down.Yes you are right. Power kites have a separate line to 'depower' them. We can also experiment and come with some improvements over that.


.... that is 340 Lbs, and also assuming 100% efficiency.I believe 6-8 sq.m. power kites can lift a 150lbs. person in moderate wind even though their Angle of Attack is not set to give the max. drag (horizontal force). With readjusted AoA, greater force is possible (I would imagine). Also, plan is to use kites above 10 sq. m. so in good wind (which is expected as we go above 150m altitude), we may get a force close to what you mention.

[airmcn_3]

You better strap that thing down good! ;) :D

[airmcn_3]

I am still not clear on how it will generate power. At first electrostatics
was mentioned. Now it seems the force on the string will do some work, don't
see how that will work.

In Popular Science a while ago was a design of a long string of small windmill rotors between 2 balloons I think. Or one balloon, tied to the ground. Really a long string, dozens of rotors. That might be more viable.


I may be wrong but I believe the kite will be attached to the string and will get pulled up at a good rate, this will turn the generator on the ground and create power. As long as it takes less power to bring the kite back to the ground or at a low altitude the system will generate more power then it uses thus making it a viable product......

Sounds good to me :D

[henkvdw]

Maybe use 2 kites. Powered to generate electricity and pull down the depowered. Once the powered is all the way up, depower it and power the pulled down one etc.

[fly_boy99]

Heck I'd like to hear about the electrical generation side of this equation on the ground.

The problem I see with this is you are depending on the weather to be constant to make your offering viable.

Not very likely...

[fly_boy99]

It looks like you need xy and z sensors and then an eagletree setup which help you out.

I don't know if you can find an all in one setup but this might interest you:
http://www.eagletreesystems.com/OSD/OSD.htm
http://www.eagletreesystems.com/MicroPower/micro.htm

B


Thanks airmcn_3.



Need:
* Air speed
* Altitude
* Kite orientation (all 3 axis)
* GPS x-y coordinates
* Voltage

I wonder if there is an all-integrated sensor module that would do all or most of the above.??

Thanks

[BeefStake]

Hmm my thoughts are thus:
1) Damn cool idea, could do alot of good in a lot of 3rd world countries just as you mentioned.

2) It's always tethered, couldn't you use a cable connection to simplify communication?
You can go 150m with no issues over copper twisted pair etc, I would be aiming to keep things simple and robust.

3) It's a kite.. I doubt there is much in the way of complicated flight dynamics so I think you should try something cheap like the Ardupilot, the IR sensors will be sufficient for your purposes and it now has a differential pressure sensor (air speed).

4) My concern is calculation of a wind vector, though I am sure this is achievable seeing as the kite will always be facing into (against? O.o) the wind.
If you have a GPS reciever on the kite (I would recommend) and an airspeed sensor, when the kite is stationary you will get the windspeed and when it is moving you can work out the wind vector from the ground-speed provided by gps.

5) The calcs required for 10kW are a little daunting but I agree with you it's entirely plausible. If you can fold the kite in the air (could be difficult because it needs to be able to withstand some pretty serious force when you want it unfolded) and you have all the electronics in a very robust case then you should be able to just let the entire system just fall to earth and let gravity do the work of restoring your kite to a groundstate.

6) Goodluck and don't hesitate to ask for help!

[HELModels]

This is a cool idea. I can see a situation where the kite needs a full autopilot to fly a Dynamic Soaring (DS) flight path. A generator on the ground could be huge and the kite's dynamic path pulls a magnet around a track.

[Helno]

I hate to be a downer but this seems like a very complicated way of making power. What happens to the poor illiterate villagers when the electronics crap out and they have a huge kite with steel wires crashing down?

A 10 Kw wind turbine can be made pretty cheap and doesn't require any man power to get going once it is installed and can automaticly feather itself in high winds.

[BeefStake]

Helno, you are quite correct.
But that it no way takes away from the coolness factor.

[mlbco]

Has anyone Googled this topic yet? There are many people researching this idea and some have working prototypes. Here are a few summary articles:

http://www.wired.com/science/discoveries/news/2006/10/71908
http://peswiki.com/index.php/Directory:High_Altitude_Wind_Power
http://www.wind-energy-the-facts.org/en/part-i-technology/chapter-3-wind-turbine-technology/current-developments/airborne-turbines.html

Some things to consider:
1) Most GPS doesn't work well at high-g
2) If you build a stationary windmill with the same swept area as the maneuvering kite they will extract the same energy in the best case scenario. The biggest advantage of the kite/autogyro is when it operates at high altitude in very high winds. If you fly near the ground a stationary windmill is simpler and proven

Steve

[jglenn]

In your first link, the kites are spinning, that is what generates power.

Not pulling on the string, or electrostatics.

Dynamic soaring with a kite will be a little difficult due to the 3D flight path.
There is no one place to hold the string, a ball gimbal on the craft will not
even do it. I think you need a string of aerial windmills, rotors, on a cable
strung from a balloon, or kite, and the ground.

[mlbco]

Jglenn,

I didn't think electrostatics was a serious contender for power generation. Here is what the article referenced has to say about it:

http://f3wm.free.fr/sciences/jefimenko.html

"Why not tap the field to supplement conventional energy resources ? Several limitations must first be overcome. For example, a single sharp point can draw electric current from the surrounding air at a rate of only about a millionth of an ampere. An antenna consisting of a single point at the top of a 60-foot wire could be expected to deliver about a microampere at 2 000 volts; the rate is equivalent to .002 watt. A point-studded balloon tethered by a wire at an altitude of 75 meters might be expected to deliver .075 watt. A serious limitation appears as the altitude of the antenna exceeds about 200 meters. The correspondingly higher voltages become difficult to confine.

At an altitude of 200 meters the antenna should pick up some 20 000 volts. Air conducts reasonably well at that potential. Although nature provides effective magnetic materials in substances such as iron, nickel and cobalt, which explains why the electric-power industry developed around Faraday's magnetic dynamo, no comparably effective insulating substances exist for isolating the high voltages that would be required for electrostatic machines of comparable power. Even so, electrostatic motors, which are far simpler to build than electromagnetic ones, may find applications in special environments such as those from which magnetism must be excluded or in providing low power to apparatus at remote, unmanned stations by tapping the earth's field. "

"Pulling on the string" can be equated to a windmill, which uses a rotational moment instead of linear force to extract the work from the wind. In either case, the swept area argument still applies and for the same swept area a windmill is the less risky and proven technology. Anytime you fly a kite (or wing) along a path to extract energy you are simply moving one element of a windmill's propeller, assuming it could execute the same path. For more energy to be available to the kite you need to prove there is a path that it can move along (with maximum efficiency) that the windmill can not.

Steve

[HELModels]

As a kid, I played around with kites. I remember a giant rogallo that lifted me off the ground. Then there was the box kite tied to an inflatable raft that powered me through breakers. There is some serious power to be harnessed.

[jglenn]

Steve:

I am familiar with the voltage gradient of the atmosphere, it is more useful for sensing than power gen. Having 20KV does not translate to power, you need CURRENT too. P = IE. Motors use electromagnetic fields because they are about 1000 times stronger.

My view is the force on a kite string is what keeps it flying. If you try to turn a reel with it, that may negate the flying function. And it appears that the energy you generate while the kite is climbing may be cancelled by the "reel in" power rqrd. Try this:

http://www.popsci.com/scitech/article/2005-11/windmills-sky

[mlbco]

Jglenn,

The article you mentioned suggests using the flying windmill concept (generating power through rotating blades and torque), not pulling on the string to generate power. Also it mentions that the aircraft will be flown in the stratosphere where the windspeed is higher. This matches what I said initially, that the only advantage over a stationary windmill is if you can place it higher where the wind speeds are greater.

Steve

[jglenn]

Yes, I think it will be hard to use the string force to generate power. If anyone does it, let's see how well it works.

I just heard of a weird way to get juice. A company is putting some kind of plates in the floor of a grocery store. People walking over them generates enough power to run the lights! Energy scavenging is a hot field today.

MEMS that use the vibration of an industrial motor or machine generate a few mW to power wireless links. Wiring in factories is expensive, they try to avoid it.

[HELModels]

The Kitegen site explains it. They describe two phases, traction and passive. The reel acts as motor or generator, passive requires the motor. The cost is 12% in the passive phase. The flight path looks alot like DS'ing. In the passive mode, it trades for altitude and then transitions to traction. The key is the control system which optimizes using sets and constraints to keep the lines untangled and maximize output.

They have a portable version which seems like what 4world had in mind.

[jglenn]

This is new to me:

The power kites are anchored to a revolving structure on a vertical axis at ground level, which conveys the energy thus generated.

http://www.kitegen.com/index_en.html

A giant turntable! It all looks too complex to me. Too much to go wrong.
Too much maintenance. A storm will turn it into a pile of scrap.

[HELModels]

YO-YO uses 2 reels to steer a two phase path.

[jglenn]

Maybe it will work, would like to see a small scale plant in operation.

That turntable is 1.7 miles in diameter!!!!!! Is that practical? On bearings?
What will the foundation cost?

How are the kites launched? Will it take 100 people to get it going?

I like the idea of offshore giant windmills.

http://www.capecodtoday.com/blogs/index.php/2006/03/03/cape_wind_now_2_work_begins_on_texas_off?blog=53

5 MegaWatt turbines floating 100 miles off shore:

http://web.mit.edu/mitei/research/spotlights/giant-wind.html

[HELModels]

The research papers answer your questions. YO-YO isnt the same mode as Carousel. The main question should be, is the research valid, repeatable. If the research is valid, then something that takes less land(depending on scale) for some output, doesnt require heavy construction, lower cost than thermal per kWh is a better way. So what if it's a kite, at least it can go up and adjust to get the best wind. The computer code controls the kites, even reels them in when conditions are wrong. Would you expect any thermal power plant to run flawlessly under all conditions, never requiring supervision?

This patent is closely related: 7,275,719

[Jack Crossfire]

U need to fly during thunderstorms with a key attached to the string. U need to make up silly phrases like "Early to bed, early to rise". Most importantly, U need a golden parachute in case the economic stimulus package doesn't work out.

[HELModels]

U need to fly during thunderstorms with a key attached to the string. U need to make up silly phrases like "Early to bed, early to rise". Most importantly, U need a golden parachute in case the economic stimulus package doesn't work out.

U need to take your meds? U are making assumptions.

[jglenn]

"Would you expect any thermal power plant to run flawlessly under all conditions, never requiring supervision?"

Of course. A thermal breeder reactor designed by the Chernobyl folks. :eek:

If it works, that is great. I have just seen too many gizmo's invented to
use up high tech something or another, like computers and sensors, or wireless,
or freaky games that are ruining kids minds, to blindly accept every new
solution. To me, real engineering balances and optimizes form and function, along with cost effectiveness. High reliability, ease of use. Geez, I think I am out of buzzwords, how about paradigm? Also the kite has a severe problem of being tied to the ground with a line, which limits the flying envelope and presents an aerial hazards to planes and species of birds which may die out from hits, along with the windmill blades and 6-pack plastic ties things that choke them.

Ben Franklin was a god, using him to make fun of your idea is blasphemy.

That's like poking fun at Tesla or Einstein. As far as power from lightning,
that is really hard. Some nuts were shooting rockets with ground lines attached during a thunderstorm, for research I guess, but I have heard of at one person trying to charge capacitors from lightning. From what I know that is extremely hard, and dangerous. Just the type of project that should be avoided.

[HELModels]

Skepticism is a good thing, as is a desire to solve problems. I know the wind and it represents serious power.

Here is an example of how powerful the wind and a small kite can be:


http://www.break.com/action-sports/Kitesurfing-gone-wrong-218933.html

[keithskye]

...

[jglenn]

Helm:

That looked dangerous. I'd think I'd stick with motorcycles if I wanted
to live a risky life! A long time ago when I worked at Sandia, they had
a strange vertical windmill in the desert. It did not matter which way
the wind was blowing. That might be a good idea. Kites have to be
launched and maintained. If no one is around to supervise, things may
go awry. This will add to the cost.

[HELModels]

That sounds like a Flettner Rotor, Magnus Effect. Jacques Cousteau was a fan of that.

As for kite power, deployment Is a hurdle. A design which is easily launched and stays airborn in no wind is ideal. Every proposed arrangement I've read about needs attitude, altitude, position provided by an autopilot. Some kind of hybrid autopilot controlled kite/plane/blimp would get up, stay up and make traction.

[jglenn]

Have the kite fold up into a cylinder, then shoot it up with a rocket motor!

The booster would drop off with a parachute, then it unfurls and the autopilot takes over.

I still like the idea of aerial windmills. Less steering. Just keep it in the air and
let it spin.

Here is a vertical mill, not as I remember it, will look later.

http://upload.wikimedia.org/wikipedia/commons/3/3c/Darrieus-windmill.jpg

[SEAN1972]

There is going to be a windmill on the kite? How will it generate power?

Since it is tethered and not free flight, the control system should be simpler,
I would think.


I was thinking of useing a dynamo like the ones on a bike for power.
As u are in the wind already then you can use it to power it as well as give you lift.

i hope this helps just an idear ill try to think of more for all the other items that are needed

[jglenn]

A fan blade on the generator? Bike generators may not be optimum, you need to consider weight and rpm. Any PM motor can be used as a generator.

But the best way would be a plastic fan blade with a hub having magnets embedded in it, then have some pick up coils. Keep the housing to a minimum.

Sending the power down to the ground is another problem, that requires wires.
Low voltage and high current will cause great losses in the cable. That is why they use high voltage AC for transmission. Wires going to a kite are dangerous, if they droop across powerlines, you will be the new Ben Franklin! Don't get shocked.

How about carbon fiber blades?

http://www.hydrogenappliances.com/bladekits.html

This looks like a useful site:

http://www.builditsolar.com/Projects/Wind/wind.htm

I have heard of Home Power magazine. Boy it would be nice to get off
the grid. Live in a cabin somewhere.

[HELModels]

generators on the ground, power from above is how to get some efficiency. Buoyancy is how you keep em up, lift is how you make power, traction is how you transmit it.

There's a kitepower expert out there who has proposed a kite tug for ships. No need for the ships to adapt technology they dont know, let the kiters handle it. A 30% savings in fuel is no joke.

As for the original topic, 4world seems to know what data he wanted and was just looking for some COTS device to help. I wonder if he found one. I'd like to hear more from Him about His project.