Advanced Kite Networks

I had a hard time understanding how it worked, and the further I went, the more problems I saw.

I will challenge the concept: How is it better than this with piezoelectric harvesting?

So this is actually the foundation of what we are discussing here?

a network of 19 circular sails with 30m diameter( 50 000 m2 in total), even with very low L/D, a power generation in the megawatt-scale can be safely assumed. This can be increased by one or two orders of magnitude by optimization of the aerodynamic properties of the sails, and by another order of magnitude by using multiple kite layers above each other.

Its like saying if you toss 1000 HAWT windmill blades, connect them with string, in the desert you get x GW output…there is no logical explanation for going from a huge kite network to electrical power on the grid. This to me seems to be the essense of what we are trying to do in AWE. It can not be glossed over like this.

I maybe should have not commented this given I have zero interest in this, and that the authors [of which there are four!?!?] are not able to answer. But then again, it would be wrong to let something like this stay here mostly unchallenged

The problem is we cant even debunk this, because there does not seem to be a single solid claim or explanation in here.

edited

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The other difficulty I had was trying to ignore excessive claims like the one quoted above.

I did not find this quote in the pdf. Please can you point to the page? Thank you.

I was looking at the links then ended up here Preprint on "Concept for the Giga-Wind Institute "Plan Humboldt" Chapter"

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Indeed page 13 of the pre-print, thanks.

2.5.8 Rough power estimate for a large-scale prototype
For a network of 19 circular sails with 30m diameter (50 000 m2 in total), even with very low L/D, a power generation in the megawatt-scale can be safely assumed. This can be increased by one or two orders of magnitude by optimization of the aerodynamic properties of the sails, and by another order of magnitude by using multiple kite layers above each other.

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I would like to supplement some of the information in this study.

Advanced Kite Networks
Authors as they appear on https://www.researchgate.net/publication/361551510_Advanced_Kite_Networks : Joe Faust, Max Langbein, Dave Santos, Jeremy Rutman. Authors as they appear on the pdf: 4 authors, including Joe Faust, Dave Santos.

Pre-print (hence the quote from the above comments):
Authors as they appear on https://www.researchgate.net/publication/354818052_Concept_for_the_Giga-Wind_Institute_Plan_Humboldt_Chapter_1 : Max Langbein, Dave Santos. Authors as they appear on the pdf: 2 authors, including Dave Santos.

I would like to thank all the commentators of this topic, especially @tallakt for his expertise on the substance.

The larger of the two documents strangely reads a little bit like a patent. One of the four authors seems to be involved in patenting. Though it is submitted on Researchgate where one would normally find scientific papers?

Looking at the one author, Mr Langbein, he did submit a paper with some other authors earlier covering many of the graphic elements and the discussion of the Payne #5 concept. This one though reads more like a scientific paper.

https://www.researchgate.net/publication/325833533_Assessment_of_an_Alternative_Concept_for_a_High-Altitude_Wind-Power_Generator/fulltext/5b28561da6fdcca0f09c4904/Assessment-of-an-Alternative-Concept-for-a-High-Altitude-Wind-Power-Generator.pdf?origin=publication_detail

The style of writing is so different though that I expect Mr Langbein was not very involved in writing the AKN (the larger) document.

In my previous comment I tried to be as factual as possible by mentioning the authors as they appeared on the two PDF (whose initial pages listing the authors speak for themselves) and on the corresponding ResearchGate (RG) pages.

Indeed RG is above all about scientific publications, but some technical documents such as patents can also be introduced. In my opinion the main criteria is if the scientific paper was peer-reviewed. I think it is the case for the paper you linked (Assessment of an Alternative Concept for a High-Altitude Wind-Power Generator) because it is an article that is published in a scientific journal as it appears on the RG page.

In RG, documents are classified into several categories, as shown in the page of research items of the profile of each author: Article, Chapter, Conference Paper, Patent, Data, Technical Report, Research, Presentation, Poster, Preprint… Generally Articles and Chapters are peer-reviewed publications.

Indeed the article you linked mentions Payne’s patent in the References.

In short, two pulleys-anchors are shown in Payne’s patent figure 5, three (to cope with wind changes) for the installation described in the article, and even more for AKN.

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The trick @PierreB in my opinion lies in the spatial arrangement of the tethers differentiating mere anchor tethers from Power Generation Tethers.

@AweEnthusiast , can you please point to the page(s) and figure(s) mentioning and describing “mere anchor tether” and “Power Generation Tethers”? Thanks.

Re-edit: After thinking about it, it seems to me that the two are incompatible, because the mere anchor tethers would fix the system, preventing the “Power Generation Tethers” from going through the pulleys, as in Payne’s figure 5 or the three pulley-anchored system.

I think everyone here is having trouble identifying what is in AKN. That’s why I proposed to take the three pulley-anchored system as an understandable basis for a further study of AKN.

Not aware of any here. Just my thoughts, @PierreB .
I am aware Jalbert Aerology Laboratories is now in possession of some trove of AWE information pending patents.

What does this mean?

@AweEnthusiast if you are defending these ideas, then can you tell me a simple thing: How do you propose to convert lift in the kites into actual energy. The interesting numbers should include the number and diameter of «spider legs» tethers, how far they move, at which frequency they move, or maybe speed, how many kites in the network at which size are needed to generate such tension and movement?

I am only interested in concrete answers here, no vague explanations.

Because - I am convinced noone has any clue about these things for AKN. We are operating in the realm of sci-fi (as in fiction). This is a place to discuss real matters.

If, on the other hand, you could supply a fair description of said values, I would be more than happy to tell you what I think about the concept.

The gauntlet has been thrown. Do you accept the challenge?

@tallakt , I think you know that it is not possible, given the description provided in the AKN pdf and the comments of the current topic, comprising mine. AKN should be seen as a start to progress, and not as a turnkey project.

In contrats, as you pointed, the publication on https://www.researchgate.net/publication/325833533_Assessment_of_an_Alternative_Concept_for_a_High-Altitude_Wind-Power_Generator provides some values and estimations. So I think you could provide an advice for this concept with three anchors-pulleys. Since AKN is based on this concept, as well as on figure 5 of Payne’s patent, we may have made some progress.

So, since I see that you, John, and me, might want to pursue the analysis, I propose to take this paper describing a three pulley-anchored system, as a basis for a further study of AKN proposition.

For that, I remark (I mentioned it in a previous comment) that going from one kite pivoting in the summit of the three tether segments to a kite network where all kites are pivoting, could be difficult at least, although not impossible. So, in order to scale more easily, the implementation of a Reversible kite in the style of Dave Culp’s OL SS kite could be a possibility. A lift-to-drag ratio of 2.5 or 3 can be expected.

My starting point with the three tether version of Payne #5 would be to look at the speed of the tether in the generator. If it is not very high, I would immediately suspect issues with tether mass/weight when scaling. Any sag developing at the slack tether will have to be taken up by the kite. This will reduce the effective stroke.

I seem to remember though, that we discussed Payne #5 earlier.

Lets assume that the tether forms an equilateral triangle where the distance between the legs is a ratio 1:n relative to the length of the legs. Then assume the kite is moving at a speed 2.5 * 2/3 ~ 1.7 times the wind speed (flying at glide ratio times a third slowdown due to harvesting power). In that case the speed of the tether at the power takeoff is 1.7 / (2n) times the wind speed. For n = 4 this makes sense, giving a tether speed of 0.2x windspeed [compared to 0.33x for yoyo].

This would mean though that is the front leg was totally slack and the rear leg was totally taught, that rig would produce less power than a yoyo based rig, with the only benefit being not flying downwind.

What I make of this is that the 1:n would only make sense for small values of n, maybe 1 < n < 3, maybe even smaller. This means again that the AWE rig would have to be large and flat and not really going to huge altitudes.

It also means that if you could make a kite more efficient, say a glide ratio of 10, you could go much higher and still use the Payne #5 concept.

Anyways - if you go low n, the tension in the tether will increase a lot. If you go high n, you will lose the ability to transfer power. You can’t add more tension with large n because the kite only provides so much lift.

For low n, you will get a high tension on the tether as the kite is pulling upwards while the legs will be stretched out. If it is high enough, tether mass will become an issue, in particular at scale due to square-cube scaling (square for kite area, cube for tether mass).

Anyways, I must conclude that Payne #5 could make sense, in particular with the right value of n and preferably more efficient kites.

If you extend from two to three legs, the winch speed will vary more depending on the wind direction, and the power takeoff must be in more than one place I presume. This will add a lot to the cost both because of more equipment, but also because the reeling speed will not be ideal much of the time. I will not analyze this further though.

For the AKN though the problem is maybe much worse as you can’t use the tether in a loop (connecting the two legs). So you maybe must use the motor to hold a force without producing power. Take for instance the legs facing 90 degrees to the network; they must have a huge tension but do not reel at all. As there is no practical way to make those legs “round trip” the tension must be maintained by either a brake or a motor. A motor will have large losses in such operation, and a brake is only feasible if there is absolutely no movement on the tether [which will only be true for legs accurately aligned to 90 degree to the wind].

That being said, I still don’t think the AKN is practically viable. I don’t see the point in debunking this based on pure speculation, when the authors have done such a poor job at actually describing what they would like to do.

Sorry for meandring in my reply here.

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Thank you @tallakt for this analysis of which I still have some points to study.

Can we say that, all other things being equal, the more pulleys-anchors-legs there are, the less efficient the system is?

Yes what I saw looked to be originally written to imitate the form of a patent.
Sorry to see you guys all taking this so seriously.
Are you really all that gullible?
We have an expression regarding the veracity of information:
“Consider the source.”
Determine whether the source of some “information” is a known good source, or a known bad source.
Next saying:
GIGO
I think we all know what GIGO stands for: garbage in / garbage out.
What you are looking at is eliciting questions from you as to what sense it makes.
Seems to me you have the GI.
Now you are asking for the GO.
And it seems that you are getting nothing, amounting to basically the GO you should expect.
Stop being so gullible.

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I forgot to add a simple problem; if you want to produce huge amounts of power on a tether, and the reeling speed depends on only kite speed, the friction must also be huge. This plain does not scale IMO. You need some mechanism to fix the tether to a PTO wheel. It you wrap it with many revolutions around a drum, twist and tether wear will appear. This is a nontrivial problem, in particular given the need for near zero friction to retain efficiency and low operating temperature

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I think I was pretty clear AKN or anything like it will not fly. Im just criticizing the idea based on my own extrapolations which seem more accurate than anything I see in a 100+ page document. Why could that be? That someone so involved in this over time, presumably years, with four people contributing, could not do better than what I am doing in five minutes on the back of an old envelope?