The AWE design on http://quak-equipment-projects.com/Visualisation/images/RechargeNews2012.pdf gather all desirable features, in first (IMHO) a maximized space, for a viable AWE system, but it is only a design. Is this turbine realizable?
How many spare billions $£€ have you got Pierre?
You’ll need them all.
Massively over complex, I reckon. But I have my biases.
Analysing this does not cost anything.
This design is very simple: a tethered turbine, an anchor. For what I know It is the only one being able to become viable in any scale for some adaptations.
If an AWES has a one km tether length involving in an average altitude of 0.5 km, its swept area diameter should be about 0.5 km, not less, that in order to avoid huge space losses that occur by implementing kite-farms with their forests of long tethers for tiny kites.
I precise also that I would not write it in another section than “Lounge”.
I am not sure I understand. Are the black and green bands the kites? They seem awfully high aspect in that case. I have never seen anything like this actually working. Anyways, what to do with this giant when there is no wind??
Yes.
From his indications: two counter-rotating sets of sails on two stationary rings. The sails carry the magnets and the rings carry the coils. The sails are not connected mechanically as their tips are kept in place by air bearings in wide supports rings.
Yes.
It is only a design.
For take-off and landing the generator works as a motor.
I think something like this design is feasible, although with other means, if a large-diameter and light generator is feasible.
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Seems highly irrealistic to me. Does those guys have already flown a kite a know all the complexity of it? Not sure.
One thing I am betting one is that AWES won’t come to concurrence large scale wind turbine at first. That is just not the way it usually happen. First wind turbine for power generations was around 50 kW. Today we are cloth to 10 MW.
If you go straight on such market as makani tried once, you would end bankrupted with no market reach.
Knee-jerk reaction would be that this is the first idea you have, you then work on it and make a thousand changes to it to get something that is completely unrecognizable from what you started out with.
The article you linked isn’t detailed enough for me to understand the underlying ideas. So I’ll say: more info needed.
The main usefull ideas of this design are both its compactness and its simplicity. I tried to obtain these with https://www.researchgate.net/publication/324135034_Airborne_Wind_Energy_Conversion_Using_a_Rotating_Reel_System, putting Beaujean’s design in References (7).
But I have also some other designs meeting other concerns, like FlygenKite.
Here is an attachment of a more complete description that seems to be no longer available on internet.
beaujean WindTech Nov-Dec 2011’.pdf (1.6 MB)
A wind turbine is a well defined object with harmonious proportions in quasi 2D. This should be the same for an AWES but in 3D.
I think I undrstand now.
Besides the high AR wings even flying, there will be challenges regarding the coils of either set of wings that need to be in close proximity.
The generator is basically applying a breaking force at the wingtips. My guess is that even with slight breaking forces, the wings will not be able to maintain their shape (even if they were nominally ok).
The weight of the coils might be an issue, as well as the powerline tethers.
None of these issues seem insurmoutable though. It seems to me that the biggest challenge would be to maintain proximity without much in terms of mechanical support. And actually I believe harvesting energy like this might cause an repellant force, making things even worse.
I would think a daisy/mesh system kite would be better suited as a starting point for such a generator, rather than the two counterrotating wings. I also think a hub generator would probably be easier to construct. Nice idea though. I would need to calculate more to say if I think this could work. My gut feeling is definitely not.
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And I forgot to mention: The counterrotating bands will not have perfect arc shapes at all times, so they might collide with severe consequences.
One more: I dont see a means of handling being overpowered. Normally one could imagine such, but here its not so easy
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Thanks for this robust analysis.
My opinion is that this design looks like a viable AWES design by its compactness comprising the tethers. But it can be unrealizable due to the requirement of “much in terms of mechanical support”.
Only one layer of wings, so without counter-rotating wings, could facilitate its implementation. Or else this design could be only a topologic model.
Then there’d be no energy extracted. Outder and inner Ring would just start turning with the blades.
Rings could have additional anchors to make this doable.
I also think this thing is totally bonkers from an engineering standpoint.
Theoretically it could work. One could probably do a nice simulation, but nothing that would make sense to try to engineer or build.
Why the permanent magnets in the wingtips and electromagnetic control of those? I don’t see any reason for this. Just split make both rings into three. A stator ring in the middle and two rigid rotor rings inside and outside, connected to the lower shorter and upper longer blades respectively. Thus a lot of the complexity is gone. Maybe two rings suffice, if one doesn’t mind the additional tether drag.
What I like is the counterrotating turbine idea.
Does any awes concept employ counterrotating turbines with flygen?
Outer and inner rings are fixed in all cases (with counter-rotating wings or without) as the tethers are also fixed. The rings hold the coils as it is mentioned.
This looks too heavy. Perhaps if counter-rotating wings are kept, putting coils on one layer of wings, then magnets on the other, that in order to double the relative speed, saving coils and magnets material.
But I don’t think the counter-rotating blades make the more interesting feature in this design that can work with only one layer with perhaps a lesser efficiency, but also maybe an easier implementation.
Certainly even with simplier variants this design could be unrealizable. It is the reason why its topology could still be kept even as the technic means are fully different.
The way I interpret the article the tethers don’t prevent the ring from turning. It doesn’t turn because the forces by the inner and outer blades counteract each other. So if one is removed the ring starts to turn.
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True. That is correct.
The first electric wind turbine was this 12 kW daisy by Brush:
http://drømstørre.dk/wp-content/wind/miller/windpower%20web/en/pictures/brush.htm
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The thing about a counter rotating design is … you’re doing it to speed up magnets passing coils for voltage… that sounds great but the tolerance, forces and weights of generator motion are restrictive to kites.
Counter rotation is possibly suitable for a small control pod with an on-board generator aloft , however the small diameter of such a generator would likely benefit from inline planetary gears too. Torque on the line is not a problem (horizontal axis) so Why not just have more gears?
The Beaujean large dia generator design may work where it can be supported in a net as a horizontal axis under a large bridge structure, where wind only goes up or down a valley …duct. A circular track can be held very tight as a tensile ring in a net. (There was a similar wind dam design with an array of many small turbines in a net under a bridge)
By supporting a large generator with a lattice or its own buoyancy you can feasibly start to consider mounting counter rotating blades… like this concept
or inside 3d tensile lattices in urban environments as in previous posts
I had explored a few larger airborne counter-rotating designs previously… some seen in
After seeing Daisy type rotor tests, you would want a very large smooth flying ring to confidently mount a 2nd internal set of rotor wings on a tensile inner ring.
I had proposed in the OM kite designs multiple concentric layers of rings in a Daisy type
However the prospect of making one of these internal layers counter rotary to the outer layers has a lot of hardware and weight implication…
The main advantage is, that one doesn’t have to counteract the torque acting on the generator.
Imagining a horizontal line with a propellor on it, the axis of rotation with hub generator bing on the line, - the line would just twist without generating energy. One way to keep the hub from turning with the propeller is a counterrotating propeller. Other possibilites include weight or a vane on a lever and tethering.
Doesn’t have to be inner/outer. Could be three lower rings one direction, three higher rings in the other direction with a generator inbetween. That way one could have only a power line to the ground and no torsion transfer, which allows for greater height.
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“Where the rotor and stator spin around each other in opposite directions doubling the speed and torque…” .(?)
The same advantage could be obtained with AWES using counter-rotating blades carrying coils for a layer, and magnets for the other layer, the rings being used only as supports.(??)