What's the story with kite-reeling?

Analysis Industry and Market Analysis
142

Spacing between flying units stems from the need to avoid collisions and the risk of entanglement in flight, as well as to mitigate the wake effect, as with wind turbines, although AWE (even kite-reeling) is advantaged by a larger and higher wind front.

Power available of 4/27 and the time of reel-in phase (= the time of power reel-out phase, leading to an average power divided by approximately 2, to be optimistic) are other parameters.

A wind turbine will occupy the area corresponding to the base of the tower plus an access perimeter, so much less than one hectare. Secondary use (farming, fishing) is easy and without risk between the wind turbines within a wind farm.

Things are very different within an AWES farm where units and tethers are flying in all wind directions, producing very high traction force, preventing an easy and safe secondary use on a perimeter where the tether length is the radius, in addition to the space of ground stations.

Therefore, there is very little chance that AWES farms compete with traditional tower wind farms.

143

For less intensive agricultural land the risks are less than autonomous cars.

E.G. pastures, forests, unpopulated mountain tops unfeasible for heavy road transport are good candidates. Also orchards and large scale crops require only a handful of working passes in a year, and not the entire space at the same time. Agricultural heavy machinery already started to be robotized or remotely operated and can broadcast their position to have the nearby kite(s) adopt a safer flight pattern in those specific days (or hours) when work is needed within their range.

It is a matter of risk/insurance vs frequency of and technical capabilities to handle accidents - most likely and serious one being a line break.

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https://thekitepower.com/wp-content/themes/plain/img/figures/space-requirements-1.svg

*Land can be used for alternative activities while Kitepower is deployed. During operation untrained people are not allowed in the flight zone.

The flight zone moves according to the direction of the wind, which means that if a farmer wants to use the land used by the AWES, he must consult the weather hour by hour, which is not feasible.

This kite, measuring 40 to 60 m², has a rated power of 30 kW, with a traction force of 2.5 T. Now let us imagine a 5 MW kite farm (5 MW would be a low value for a tower wind turbine farm): the total traction force would be more than 400 T. An unexpected gust of wind carries all of this (tethers and kites) away, which will drag for dozens of kilometers, destroying everything in its path. “Autonomous cars” would be toys in comparison.

We could try putting AWES farms in desert areas (like the one we see in the tests in China), but then we would have to add the electricity transmission cable over long distances, in case everything was running continuously.

145

Moritz Diehl has a great study on the potential of AWES to improve energy density / km^2
Vertical Airborne Wind Energy Farms with High Power Density per
Ground Area based on Multi-Aircraft Systems
arXiv:2211.15813v1 [eess.SY] 28 Nov 2022
Jochem De Schutter1 , Jakob Harzer1 , Moritz Diehl1,2

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Windfarms in unidirectional wind resources such as Palm Springs or Tehachapi are laterally spaced more closely.

147

The general plan of the M-AWES farm (which could be replaced by parasails covering the same circular areas called n) shown in Fig. 1 seems suitable although obvious.

In the page 2, it is indicated that Betz limit (16/27) is considered for each of the units. So the AWES mode cannot be reeling (yo-yo) mode, being limited to 4/27 and divided by approximately two due to the time and energy of the reel-in recovery phase, i.e., eight times less. And yet there is a clear reference to reel-in and reel-out phases (for example on page 3)…
Thus the density is divided by about eight.

The angle of elevation of 40° in Fig. 1 looks possible although optimistic.

And above all, the tether lengths are not taken into account for the calculation of the density when they should (by taking account of all wind directions), due to safety issues in secondary use (farming or fishing), not to mention the risks of kites and their tethers being dragged for tens of kilometers in the event of breakages.

In the end the AWES-farm density is a tiny fraction of what is suggested.

1 Like
148

It looks like I opened this topic about 7 years ago. Since then I see hundreds. maybe more, messages, mostly me lamenting the lack of answers.

Long before that, in the old forum, maybe around 2013, I remember posting “time’s up, show us your working system” after, already by then, years of hype and at least hundreds of people involved in kite-reeling.

In all that time, we had what, maybe 5 or 6 years of Pierre repeating the purported Skysails numbers approaching 100 kW output? Then the “press-release” period of peak “success” when I was chastised for not “understanding” that Skysails now “had a factory mass-producing kite-reeling systems, being sold worldwide”… which turned out to be limited to the sole orphan installation on the island of Mauritius, which never seemed to actually run.

OK so I have been totally disgusted with the whole AWE crowd for going on 2 decades now. And these forums seem to be 100% worthless in the following way:

  1. The “official” main theme for AWE, if there is a main theme, seems to have been kite-reeling.

  2. After 17 years, there is still not a single kite-reeling system in regular operation, in the world.

  3. I’ve asked repeatedly what exactly is the problem(s) holding back kite-reeling from daily operation.

  4. We’ve never gotten even one single answer.

  5. This forum is supposed to be the main source of knowledge for AWE

6)So the “main source of knowledge for AWE” has NO IDEA WHY the MOST COMMONLY PURSUED METHOD for AWE has no system running in daily operation after 17 years.

To me. this is absolutely absurd, and seems to reinforce the extreme ignorance here. Not only is everyone ignorant of even the most basic facts of wind energy, needing even the most basic “ABC’s” explained to them ad infinitum, but apparently everyone here is either 100% ignorant of AWE itself, if they can’t tell us what is holding back the main technology that’s been promoted by most AWE comp0anies for 17 years and counting.

So out of what, maybe 1000 kite-reeler people, nobody either understands, or i9s willing to explain, what problems are holding back kite-reeling? I mean, most of the companies gave up, so there’s no longer any reason to keep any secrets, right?

I’m not going to even ask what the problems are anymore. I give up. Not only is everyone in the AWE crowd ignorant of wind energy, they are either ignorant or for some reason silent on what challenges have been holding back the main avenue pursued for all these years!

Let me go back to “real” wind energy for a moment. Let;s look at vertical-axis turbines: The first windfarm in Tehachapi consisted of “FloWind” brand vertical-axis turbines. Professor Crackpot was obviously involved with that first windfarm, and as a result, ALL of the FloWiind vertical-axis Darroeus turbines had to be dismantled and removed withing the first year. The vertical-axis turbine were replaced by “Kenetech” brand horizontal-axos turbines that lasted a bit longer then the verticals, but also had to be replaced within a few years since windfarm turbine production was a new art, in need of some refinement. It turned out that turbines had to be more robust and expensive to survive what mother nature had to dish out.

The point is this:

The inherent problems that afflicted the Darrieus vertical-axis turbines are well-known, well-documented, and often discussed. There is no mystery. Honest engineers and practitioners have analyzed the economics and failure modes, and the concludsions and the reasons for the comnnclusions are well-publicized for anyone who is interested.

NOT So with kite-reeling. Kite-reeling, and AWE in general, seems to fall neatly into the “scam” territory, where only false promises and hopeful “positive” aspects are discussed over and over, such as “stronger winds at higher heights”, “less material used”, “less intermittency”…

It alll sounded great, but now we face the basic dishonesty of not only crackpots, but your typicall ripoff artists selling plastic toys on EBay, where facts are unwanted and not even allowed, in leiu pf endless fraudulenty sales of complete junk based on only extreme lies. I saw a PhD college professor online the other day on a home wind turbine forum asking about the details of a one of these supposed “3000-Watt” plastic toys on Ebay, to power hos house. He obviously knew absolutely NOTHING about wind energy, and just assumed what he was reading on Ebay was true - real specs. Oterwise, how could Ebay allow them to lie, right?

Well we seem to be in the exact same position in AWE, except nobody is selling any systems, but investors have been similarly ripped off for going on 2 decades now, by being spoon-fed false information, with ZERO actual facts about what the probolems are being even discussed on a flrum such as this!

I am legitimately curious about ALL wind energy systems, and would like to understand how kite-reeling actually fits in to the spectrum of wind energy designs and results. But there IS NO INFORMATION that I’ve ever seen. Nobody seems to discuss any of the dealbreaker details that MUST be present lest we see systems actually in daily, product9ibve operation somewhere.

So I’ve gotta say, I’ve gotta throw all these years of supposed “discussions” of AWe in the wastebaslet. I’ve learned NOTHING in all these years of AWE discussions except how badly behaved the people involved can often be, and how they predictably have enjoyed prety-much zero favorable or useful results. Oh well, if anyone who knows about the problems that stopped the main focus of AWE from ever emerging, enquiring minds like mine wouold like to know. Otherwise I’d say this is a complete intellectual wasteland. :slight_smile:

149

Not surprisingly, nobody here has anything to say about why the most commonly pursued method of AWE has gone nowhere for 17 years and counting…

After all those group selfies… “Look Mom!”

BTW, when experienced wind people see a group selfie of 20 or 30 people, all they see is a sinking ship weighed down by its own overweight payroll, combined with a lack of experience, like watching lemmings heading for a cliff!

Oh well.

150

My reply is much the same as before.

Imagine a task difficulty x and a team with capability y. The chance of success is a function depending on these P = f(x, y).

It is clear to me that for kite reeling, P_max = maximum(f(x, [any number])) is a quite small number. It’s very hard to develop kite reeling wind power. And y varies as well.

Time passing does not say much really. You can count the projects done at certain costs and estimate the value of P_max and y if you want. Perhaps even you could say P_max is so small, given the teams being so many and on average being capable, that P_max inevitably must be so small that the investment does not make sense business wise (eg. $ × P_max < [value of developing AWE])

Given the time past and my heavy involvement in one such process, I can attest at least to the value of P_max being pretty small. Though if there is business sense with the right team (y) I don’t know. I can say though that I would probably spend my last part of my career investigating rotary AWE rather than reeling AWE, or some combination, rather than the traditional reeling [bounding] AWE idea that many adopted.

151

Thanks Tallak for considering my question. And since you were involved with ONE kite-reeling company out of maybe, what, 20 or 30(?) I don;t expect you alone to completely answer the question. But your perspective is important.

To me though, since it contains no details of “What is the problem with kite-reeling?”, its a non-answer, something more like we would expect to hear from a politician. (Sorry for that comparison) You throw out a couple of X’s and Y’s and pretend you have said anything at all.

What I’ve been asking for is something like “The problem is when the wind slows down the kite needs human intervention to stay airborne” or “the kites tend to wear out within mere hours”, or “Nobody could ever achieve automated launching and landing”, or “The high power numbers floated around were selected moments and overall output has always been dismal”. What about “The actual reeling mechanism, feeding the line back and forth on the frum, tended to tangle and bind, and no kite-reeling company could ever get that to work out”.

Instead, what you’ve said, in my interpretation at least, amounts to “We never had any idea what we were doing in the first place, and every aspect of kite-reeling has been so challenging we could never get any aspect to work”.

In that case of that last passage, how could it go in for 17 years if nobody was enjoying any success whatsoever? And why would Skysails announce production from a factory and sales around the world if they never had anything that really even worked well enough to run on a regular basis?

I know I’ve said it before, but even I have been surprised at the fact of NOTHING running regularly after all these years of hype and especially the attitude expressed by so many, that because people like kite-surfing, they are way smarter than real wind energy people, whose remaining days, with their stupid towers, are limited, by how smart we are!.”

And it is not limited to kite-reeling, although that is the favorite approach overall. I thought that efforts like Makani, promising to power X hundred homes in remote location Y by date Z were based on whatever promising results they were gettinig so fa, and has at least SOME factual basis.

In my mind, I had never seen that much effort and money go into wind energy devices that basically did not even work at all. I had expected Makani to indeed power hundreds of homes, intermittently, at some high cost, which might be OK for early versions, but then the financial numbers would become apparent, indicating that such “drag” machines could not in fact produce power cheaper than tower-mounted turbines. I assumed the automated launch/land would be a problem, burning out generators might be a problem, but that overall, at least they had something that worked well enough to uSE at SOME cost.

Nope, my original observation that was simply “none of these people knows what they are doing” seems to have emerged as the actual case. I mean, really, ZERO success AT ALL after all these years, a thousand people, and over a billion dollars spent? I am just blown away. I though at least system of both types could at least run on a regular basis for at least maybe a week or two, but just not be better than the existing technology, but instead, NOTHING. Wow. And apparently, if i am reading between the lines properly, no aspect of any pf thes approaches was ever working out. Absolutely amazing. I think one salient aspect was how many AWE wannabes denigrated regular wind turbines, promising t0 replace them, promising GigaWatts from vaguely-described domes over craters with trains hgoing up and down the walls of the crater, for example. That is one extreme end of a spectrum that, as it turns out, every single player was unknowingly a part of. Wow. So nothing about kite-reeling ever worked out, at all, yet we were subject to 17 years of global warming derangement driven hype. Sheesh! Well, life goes on, and here at least, it;s another beautiful day! :slight_smile:

152

I believe my reply is the end of the discussion in many regards, because I am saying [again] that people failing proved nothing. If you estimate the variables involved, each failing team supports your theory that reeling [what I like to call bounding] AWE is not worthwhile in some way.

If you expect everyone to accept that this design of AWE is not worthwhile at all, you will not progress in changing people’s minds. (From where I stand it seems you have not made much headway so far).

We could discuss individual pain points but I don’t think there are any identified to this date that is a full showstopper in theory.

As long as the argument is “it is too difficult”, “its not worthwhile” or similar, this discussion is stuck.

1 Like
153

Hi Doug,
You keep writing and rewriting the same post about kite-reeling. However, there are several modes and equipment types: crosswind, rotating, tethered-aligned, flexible kite, rigid kite.

It will therefore be very difficult for you to distinguish between what pertains to the kite-reeling method and what pertains to the equipment or the mode.

Let me give you an example: the control issues during takeoff and landing are not the same with a rigid kite and a flexible kite. Therefore, you cannot conclude that the problem stems from the kite-reeling method.

You should refine your analysis.

155

Hi Guys, and thanks for your input. What I’ve been trying to get to is some balance between the often overly-optimistic hype we are barraged with, as these companies emerge from nothing, and expect the world to literally be convinced by claims of being “really smart” and how many kids they can get together for a group-selfie, and the details of their results, whether good or bad. Instead, we just get barraged with more complete bullshizzle, like someone denigrating me for “not understanding that Skysails has a factory mass-producing AWE systems and selling them around the world”. Gosh, skeptical me, with no evidence whatsoever except my experience with wind systems, I just held my ground and proclaimed all that marketing hype as deceptive, 100% wrong information. Who turned out to be right? Do I ever get any credit for telling the truth in the face of a firehose of lies?

I’m in this as a person with actual INTEREST in the technology, and would love to have been proven wrong about kite-reeling, but the supposed “discussion” never actually takes place AT ALL. There is no actual discussion, just marketing lies.

One might suppose, in two alleged “discussion” groups about AWE, with so many “teams” exploring “kite-reeling” that we would enjoy learning details of the positive, and the negative salient aspects of what is being discovered. All the initial hype is supposed to get people excited to follow the continuing story, but there is no continuing story, just silence.
This is because, as technically-interested people, we like to learn how things work. We are shown endless pictures of half-size shipping containers emblazoned with painted-on logos, shown a few laborious-looking flights, then expected to just forget about any detials as the more astute of us (me) keep noting that, after all that hype, there never seems to be anything actually running on a regular basis. Yet we never hear a SINGLE account of what the problems holding back progress are. We are left to just guess. Now i do understand the concept of “trade secrets”, which seems to be more about not revealing how bad things are going, so more funding can be raised, but at some point there is the natural curiosity and thirst for actual information, like “the tethers keep breaking” or “turned out we needed a bigger generator”, or maybe “the darn thing just didn’t ever fly that well” - whatever the facts may be, what is a “discussion” without ANY details, ANY facts WHATSOEVER - just the hangover from knowing I’ve been barraged with marketing hype, told to expect great results, then it’s just “radio silence”.
OK so “trade secrets” no longer matter for projects that have been abandoned, yet we STILL never hear any details of the projects that have generated so much interest. I guess Tallak’s explanation kind of amounts to saying that EVERY aspect was problemmatic. And i do respect that he doesn’t necessarily want to hurt any ongoing efforts from his former company by spilling details that might reflect badly on their ongoing efforts, whatever they might be. But I do not accept as valid, being told the same hype by 20 or 30 companies, with zero followup as to why nothing they promised ever came true. Way back when this hype-fest was all getting started I do remember telling that one guy who always wanted to argue with anything factual, that such wind-wannabes eventually “quietly go away”, but in previous cases, such as vertical-axis turbines, the problems are documented and everyone talks about them. it is a learning experience for everyone, and that is how the art of wind energy advances - with shared information whether good or bad, it is all helpful, instructive to the next batch of wind wannabes, should they decide to actually learn anything, and a necessary part of progress, otherwise the next batch of wind wannabes will just make the same mistakes again and can rightly say “nobody told us!” in the end, to me, the whole thing started out as mostly dishonest hype, and I think nobody wants to admit it, or ever have an open discussion about what has been the main theme of AWE for almost two decades now. oh well, I guess candor or useful information is too much to ask. If someone kept telling you how great it was going to be when they jumped off a cliff, and then came back later severely injured, you’d expect to learn why jumping off a cliff turned out to be a bad idea, like “Everything was going so well until i hit the ground and broke both legs!” Not so with AWE - they just go silent after all those empty promises. And I am also not saying anyone has “proven” any general category cannot work. But the results we’ve seen so far point more toward dishonesty revealed, than anything to get excited about. And as far as using the term “kite-bounding”, have fun with that. Once again, the tendency is toward just dishonesty. Kite “REELING” describes what is going on. I think I was the one who coined that term. Kite-”BOUNDING” is designed to obscure what is going on, as in “Let’s make sure nobody knows what we are talking about”. Silly. the whole scenario is pretty silly. :slight_smile:

156

Indeed. However, Makani (not reeling yo-yo mode) has published numerous reports and videos detailing the malfunctions and also successes.

Since Makani was developing a rigid crosswind flygen AWES, one can expect that some malfunctions might be similar to those encountered in rigid crosswind AWES in reeling mode, but if they had the same dimensions, which does not seem to be the case, except if one takes into account Makani’s first wings, which were smaller, but we do not have complete reports available for them.

If malfunctions specific to reeling mode are observed, such as problems related to electricity generation by winches during the reel-in and reel-out phases, and if these problems also affect the flying equipment, it would be useful to know.

157

Hello Pierre:

If the most commonly-pursued method of AWE has produced no product, nothing in regular operation after 17 years of supposedly trying, with as many “teams” and people involved, yet we have pretty much ZERO accurate information, and 100% INACCURATE information, with ZERO of the promises coming true, I would like to just fall back on my initial impressions:

  1. NONE of these people has ANY IDEA what they are doing.

  2. The phrase “idiots, idiots, idiots” seems to characterize the situation most accurately.

  3. Getting the world all excited about this SUPPOSED “sustainable” energy “breakthrough” was deception, plain and simple. Yes, zero output, or close to it, with nothing running on a regular basis, is “sustainable” and in fact has been sustained for 17 years now:

  4. Offering ZERO follow-up info after getting everyone so excited is just unacceptably rude behavior. Like luring people into a theater with the promise of a drama with a fantastic ending, then stopping the move halfway through with no explanation. Very weird.

  5. And that’s just from the viewpoint of people who find the subject matter interesting LET ALONE the people who were conned out of their investment dollars, which may be verging into the category of outright fraud.

  6. This is not one or two “companies” but universal, across the board.

So I’d say it shows a lack of basic good behavior or even just good manners, across the entire spectrum of the kite-reeling “industry” (which never actually became an industry at all).

  1. Finally, somewhere around 2012, I remember trying to summarize my negative impression of kite-reeling as a legitimate endeavor with the simple phrase “Kite-Reeling: Hmmmph!” and that has turned out to be accurate.

Pierre, you have repeated for what, maybe 6 or 7 years, the supposed high power output numbers from Skysails’ testing, every time I openly questioned kite-reeling, which is good to consider, but at some point meaningless if that was the end of the story.

The other thing is, how could Skysails have announced their “factory in mass-production” with “sales around the world” when it all amounted to a single system going to (of course) “a remote island” with zero followup info on whether it even operated for a single day feeding the local grid. (???)

This is all SO despicable on the scale of business behavior, I have to say, at one point I had thought people who like to fly kites were in a higher class than the average person, but today I look at them as mostly scumbags, kind of like street bums, and I think maybe you can identify at least a couple from our previous experience, in all surprise to me. And really, to be ignorant of some subject, like wind energy, is in no way a mark against any normal person, since none of us can be an expert in every disparate field, but to claim one is smarter than all the expert practitioners of an art, from that same standpoint of ignorance, THAT is when ignorance and arrogance, become a fatal combination. And that goes double when outright dishonesty is added to the disaster. :slight_smile:

158

Indeed, SkySails has reached quite high values (average 92 kW), sufficient for the reeling-kite (yo-yo) mode to be the mainstay of the AWE field.

See also an achievement of high values with the 5000 m² Chinese parachute, also in reeling mode, also with a flexible flying body.

159

OK this is exactly what I mean. Skysails also announced a factory mass-producing kite-reeling systems and selling them around the world, “starting in Asia”, if memory serves, and that was all maybe a decade ago by now? I was chastised on these forums for expressing skepticism, and told “apparently you are not aware of the skysails mass producing and worldwide sales” or something to that effect. I was like. these AWE wannabes will just believe the same lies over and over again, or mere wishes, stated as facts. You’d think the people here, being interested in AWE, would be the first to call their bluff, but no, here is where we find the most gullible people of all. I seem to be the only one besides occasionally Pierre that ever scrutinizes any of the endless false statements from AWE companies. As it has turned out, such false statements of future progress seem to be about all there has ever been in AWE. There is a saying , something about “If wishes were fishes”…

OK I looked it up:

“If wishes were fishes, we’d all swim in riches” (or “cast nets in the sea”) is a proverb emphasizing the futility of wishing over taking action. It means if desires were easy to obtain, everyone would have plenty, highlighting that wishing alone does not produce results; hard work is necessary.

That’s all fine, but today’s “fake it ‘til you make it” culture subtly turns mere wishes into outright lies before we realize it.

Joby was an early AWE player. Today they have pivoted to EVTOL’s that “will” take passengers to the airport by 2025. There we go again - has anyone ridden in an EVTOL to the airport yet? Anyone notice a pattern here yet? Wishes are not fishes. :slight_smile: