What's the story with kite-reeling?

Ok Rod, sorry I came back. Doug, the New Forum is all yours.

So you, as a self-described (To Peter Harrop when demanding a free copy of his “report”) AWE “domain expert”, have NO information on the status of the most popular (how can a million floes be wrong?) style of AWE being pursued, is that right? People like you can’t even grasp that Peter Harrop’s opinion is irrelevant, let alone your own. Ignorance analyzing ignorance - wow.

(That’s "How can a million flies be wrong, not “floes” - sorry.)

You know it would be nice if, when one replies to a comment, the reply would appear nested / indented after the comment to which it pertains, rather than just appearing at the end of a long list of comments. This is to Rod and Pierre where Pierre said there’s no kite-reeling system in regular operation because nobody who owns a house would know where to put it, and Rod agreed it was a “fab reply”. Reminds me of daveS’ “concert that never happened”, where fans of the idea of AWE are so far into fantasy-land they can’t even figure out that implementation of a working system requires such a working system to exist. OMG I feel like I walked into an insane asylum!

Doug, this comment was about the topic, not about another comment. And please read the answers, of which Rod’s you mention, playing the signs in the top and the right of the quotation to go to the comment itself then the answers.

Doug, the comment you allude about house is on What's the story with kite-reeling? and Rod’s reply was not about this comment, although it apppears just after. In fact the reply for this comment was yours. You can verify it.

The comments and the replies are well indicated.

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A post was split to a new topic: Disruptive Innovation

sorry didn’t follow the whole conversation, but what is kite reeling? is this the same as pumping mode?

Kite reeling = reel-out/in = pumping mode = yoyo.

thanks! I don’t see a problem with kite reeling. I think most AWE companies/research facilities pursue it, Ampyx, Kitepower, and fly on regular basis.

But i see a problem with not doing kite reeling when you have additional weight on your wing from the generators…

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Kite-reeling is perhaps the first thought a natural tinkerer has when flying a kite. It goes something like: “Gosh it sure would be easier if this reel were powered”, transitioning to “Heyyyy, wait a minute… What about a reel that MAKES power!!!” Which places the least-effective type of wind turbine, a Savonius, into the sky, except the kite can fly crosswind as it reels out, so it is moving downwind, but veering around - not as bad as if it were just traveling straight downwind. But like the Savonius, it makes no power on the upwind cycle. And worse than a Savonius, this makes most kite-reeling systems intermittent. So the questions are, in spite of these factors, is it showing promise? Or is it working well already?
The reasons kite-reeling is so popular are
a) it was so easy to think of - almost invented itself;
b) the kites are available off-the-shelf
So it is relatively easy to understand and implement, even for beginners, within the time constraints of academic calendars and getting a graduate degree.
The question was never “Does it work?”, because it is so simple that it HAS to “work”, but, there are unlimited configurations that could return SOME electricity from wind, at SOME cost. The question is, is it WORTH doing? Does it return enough to matter? Enough to compete with alternatives? If not, does it show promise that it can in the future? With further development? Is it “looking good”? Is everybody high-fiving, or are they going home frustrated and disappointed? So I guess, given the number of teams trying it, and the generous budgets, and the announced grid-feed projects, the question for AWE people is “HOW is it working?” Is it just barely scraping by, or is it performing phenomenally? Is it being run every day, or is it just dusted off and taken out occasionally? Normally in wind energy, long-term operation is required to show survivability and long-term reliability. A single operating period of an hour or two is nice to show performance, but if it only lasts an hour before breaking, even the best performance is still not enough. So it would be nice to hear some details. Also, when a company is providing lots and lots of (extraneous) details, then suddenly stops when the details that actually count are scheduled to begin, it suggests maybe the silence is evidence of a problem, since they were so happy to share info until power was supposed to start being generated.
Also, why is there still no facility powered by kite-reeling? Why is there no daily grid-feed from kite-reeling? It seems that any company would be happy to publicize such daily operation or daily grid-feed, if it were taking place, given the amount of detail they go into while just preparing for grid-feed operation. The silence seems conspicuous. No products for sale still? Why exactly? One might assume that a successful and happy testing program would be hard to stay quiet about. After all that work, and all that pre-grid-feed hype, you would assume good performance would be irresistible to brag about - just a little bit. Maybe someone knows more and can fill in some details.
When I ask “What’s the story?” it’s an expression of curiosity derived from a strong interest in AWE, and a response to the ample information disseminated by high-visibility teams (bragging ahead of the fact?) as they prepare to feed the grid, contrasted with the common “news blackout” that emerges, pretty-much on schedule, the moment that grid-feed is scheduled to take place in the AWE world. This seems inconsiderate to the fan-base these companies slowly build up, only to abandon them when the hype is expected to transition to a reliable, economical grid-feed power-generation project. It also seems intellectually dishonest, since in science and engineering a negative result is still a valid result that should be communicated. It’s like they write and produce a TV drama, but just as the show is supposed to be having its happy ending, the screen goes blank. At that point we may never hear anything from them again. Which leaves us wondering “What’s the story?”

During reel-out phase there is average power loss due to lower apparent wind. During reel-in phase there is average power loss due to higher apparent wind.

That is so poetic. :slight_smile:

Thank you Rod - good info. Dyneema tethers. Seems like the thing to use for strength. Or so I keep hearing. UuuuHmpME. The real reelers. Hmmm. Will the real reelers please stand up! We have a lumber company called Reel Lumber in Southern California.

I dont think Savonius and Yoyo AWE are directly comparable (though i see the similarity with the windmill blades movibg downwind).

This has been discussed to some detail already though, savonius or another structure going downwind even does not make in itself AWE infeasible. Many people (including myself) seem to believe that less energy dense constructions could succeed as they may be cheaper in construction and maintenance, even if they dont extract the Betz’ limit worth of a given area of wind passing by.

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As attachments a study about “Inertia-Supported Pumping Cycles with a Roto-Kite”.

From Poster_DeSchutter.pdf (526.7 KB) :
“…the roto-kite continuously extracts energy from the wind,
storing it as kinetic energy during reel-in…”

The same study as an abstract:
ch18_awec85_DeSchutter.pdf (636.3 KB)
.

That first poster Inertia-supported pumping cycles based on a roto-kite
bemuses me… (OK, I’m thick and I had to look up all the mathy terms)

Right so it’s a pumping yo-yo but…

The quasi-sinusoidal, high-frequent reel-out pro-file could e.g. be realized by connecting the tether at the ground station to the rotor of a vertical-axis generator.
eh what? Why a vertical axis? Not just a normal (for AWES) pumping ground station? It’s not harvesting around a vertical axis. It’s a single line pumping.

at the start…

small power-to-mass ratio

power to mass ratio will surely depend on the design, you’ve got a stackable design … and you know, tensile rings could work here too…

Bemusement #3 … figure 3… -P kW is that what we’re harvesting? -ve power? There’s a lot more of that than +ve power in that graph.

Obviously, I’m far too thick to understand this. However, IMHO, this poster isn’t exactly giving off an air of accessibility.

Also the 1Hz cycle, that’s going to depend on the model size … So is that 1Hz per a big screwing with loads of turns? Is it 1 short part of a rotation?

So it seems Im also too thick for all hhat math, but the gist of it seems to be that we are still producing energy while reeling in, and storing it in in increased momentum?

For that to work the kites would have to accelerate really fast with minimal tether force applied. This again implies spilling wing lift while retaining a large lift to drag ratio.

Its an interesting thought, and would probably only be possible with very short production-retraction cycles, as increasing the speed of the kites would quickly make the lift force get out of hand.

It also places some extra stress on our tether budget, as tether tension in return phase is not minimal anymore, so we need to compensate in production phase with even more pull than usual. But with the Y or rotor kite construction, this should be possible

Super interesting!

In practice I would expect not to increase momentum this way, but rather counter the effect of gravity slowdown