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Want to Generate Energy? Go Fly a Kite
11/12/2012

One of the test kites being used to create energy according to a method designed by Nature Technology Systems in Germany makes its first flight. The company -- which partnered with Fraunhofer Institute for Manufacturing Engineering -- said the system it created uses the same principles as wind turbines but is more efficient and environmentally friendly.   (Source: Fraunhofer Institute for Manufacturing Engineering and Automation IPA)
One of the test kites being used to create energy according to a method designed by Nature Technology Systems in Germany makes its first flight. The company -- which partnered with Fraunhofer Institute for Manufacturing Engineering -- said the system it created uses the same principles as wind turbines but is more efficient and environmentally friendly.
(Source: Fraunhofer Institute for Manufacturing Engineering and Automation IPA)

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Elizabeth M
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Blogger
Re: End of the Track
Elizabeth M   11/13/2012 4:19:27 AM
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Excellent points about aircraft concerns. Lights could be one option; however, I'm sure as this system continues to get tested this will be addressed. One easy solution would be to try to put them in areas where there aren't often low-flying craft. Staying far away from airports is an obvious solution to that.

mrmikel
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Iron
Re: End of the Track
mrmikel   11/13/2012 9:43:17 AM
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I think the only solution for aircraft concerns would be to ban aircraft from the area entirely.  This is especially true since in the US, aviation is moving away from flight paths to routes decided by pilots through GPS tracking.


This is not unprecedented.  There are many areas off limits to aircraft already.


It does remind me a bit of barrage balloons during Word War II I read about.

deejayh
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Silver
Kite Control
deejayh   11/13/2012 10:59:42 AM
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A close view of the picture shows four lines going to the kite.  This might imply that that 4 lines are needed for strength and or redundancy.  However, it also implies that the kite would be capable of being directionally controlled (tacking) allowing it to fly in directions not directly downwind.  Nothing mandates that a track mounted generator can't store enough power to propel itself while tacking crosswind down a track perpendicular to the wind for the brief period needed to navigate the half loop at the end of an oval track.  Then there's the design study needed to show if a figure 8 track (allowing more downwind travel) of a given distance would provide more net power than an oval track with a given diameter at the ends.

CLMcDade
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Gold
economically feasible
CLMcDade   11/13/2012 1:03:30 PM
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Unlike solar farms or windmills which are inherently difficult to look at or follow with the eyes, advertisers could use these kites to place their logos on truly unobstructed billboards, and not cut down any trees in the process.  So capitalism could serve environmentalism for a change.  And vice versus.

Of course, the kites would have to fly in a public area, but those are the small details.  : )

Jerry dycus
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Gold
Re: Kite Control
Jerry dycus   11/13/2012 4:01:18 PM
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Yes you need 4 lines for control.  While it looks interesting it has many problems too which I han't seen fixed yet by any proposal I've seen. 

 

The [problems of wear, line entanglment, power transfer,  height, aircraft make these hard to get right.  I doubt anything above 1000' would be practical and even 50' problematic.

Cloth isn't going to get it as they wouldn't last long and hard kites have their own problems.

 

 A better idea is the old 3blade wind turbine I believe until someone can show me a viable kite system that can last.

I should say here I've sailed and design, build high speed sailboats plus wind generators and have never firgured out how the 2 can be combined after 1,000's of hrs trying.

 

engineerBob
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Iron
Re: End of the Track
engineerBob   11/13/2012 6:09:03 PM
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Am I missing something? How could the generator car possibly "loop back" when the kites are pulling in a vector that probably won't vary by more than 45 degrees?  Assuming a long narrow oval track at 90 degrees to the wind, on the straight legs of the oval the kites would only be providing a portion of the total force anyway: moving the generator first to the left, say, on the up wind straight leg, then following the wind direction through the first curve, then the kite would have to tack to the right, pulling the generator to the right on the downwind straight leg, then it would get to the next curve, somehow proceed against the kite force and midway through the curve the kite needs to reverse tack to the left, the generator still working against the kite to get back to the straight leg.  If this works they've discovered perpetual motion.

tekochip
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Platinum
Re: End of the Track
tekochip   11/13/2012 6:32:57 PM
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No, mrmikel, most General Aviation flights are still Visual Flight Rules.  Commercial Aviation typically flies Instrument Flight Rules and at altitudes that wouldn't cause any problems to this system, but small planes would have real issues.

William K.
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Platinum
Kite generating systems
William K.   11/13/2012 9:05:23 PM
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The version of the kite-type system that I saw that made more sense put the turbines up in the kite. The generators could be run as motors to fly up into the wind area, thgen revert to generating power from the high altitude wind. The major problem with this approach was the transmission of the power back to the ground. My suggestion is to use quite high voltage and separate cables for each phase. Then you could have a twenty kilovolt transmission line with fifty feet of separation. It really is an interesting concept, and less complex than flying a kite in circles. I was never able to do that in a sailboat, so why should it be any easier with a kite.

Sawmill Engineer
User Rank
Iron
Sounds like we're out to harvest investors rather than the wind...
Sawmill Engineer   11/13/2012 9:28:04 PM
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"the faster a kite flies the harder it pulls".  Meh.  Last I checked, kites were pretty much stationary in the sky and the wind moved past them.   This statement makes no sense.

Yes, if you pull in the kite it will pull harder because you are increasing the relative wind speed the kite sees.  But a kite is basically a stationary device that provides lift when air moves past it.  

It strikes me as they are chasing an awkward way of achieving power with railway tracks and the like.

A far simpler way would be to build the kite so you could dynamically play with the lift and drag, and operate the kite in "cycles".  You would set up your kite cable winches to be able to spool the cable in and out, and any necessary braking on the winch drum(s) would be converted to useful energy. 

The first part of a cycle would be with the kite flying high, at the desired high altitude, (read: higher wind speeds) but pulled as close in to the winch point as possible.   Now, change the kite characteristics to get maximum drag while just maintaining the desired altitude.  Begin letting out cable and harvest the energy from the pull of the kite.  Depending on the airspace you are allowed to operate your kite in, this may be many thousands of feet downrange.

Once the kite has reached the far end of the cycle, you need to bring it back to the starting point. Presumably, from the data the company has provided, there are lower wind speeds at lower altitudes.  Therefore you pilot the kite, again by playing with lift and drag on the kite, to minimize the drag and allow just enough lift to bring it back upwind with your winches, presumably expending less energy than your gained by the wind towing the kite downwind. 

Sounds like a cumbersome way to harvest wind energy.

 

 

 

Dave Palmer
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Platinum
Benjamin Franklin kite story
Dave Palmer   11/16/2012 3:18:28 PM
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While the Benjamin Franklin kite story is known to just about everyone who went to elementary school in the U.S., it's almost certainly untrue.  Franklin wrote an article suggesting a version of the experiment, but he didn't claim to have actually performed it himself -- and if he had done it the way it is usually described, it's unlikely that he would have survived.

That being said, I teach a U.S. citizenship class, and always mention the kite story to my students (along with the story about George Washington and the cherry tree, which is also probably a legend).  First, because it's a story that most people who grew up in the U.S. know, and is a part of our popular culture.  Second, because Franklin's scientific fame helps explain why he was chosen to be the U.S. diplomat to France during the Revolutionary War, which is what USCIS thinks you ought to know about him.

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