Please have you some idea from http://www.swayturbine.no/?page=219 to a very large diameter generator that is very light and could be flexible. The larger it is relatively to the whole system diameter the faster in linear speed it is, that may lead to a lighter generator per power unity.
For this small study, the generator (stator + rotor) is studied outside any other element. Thanks.
1 Like
Pierre: The extreme example was the failed Honeywell rooftop turbine that had the generator on the rim of the bicycle-spoke-type, typical professor crackpot, way-too-many-blades bicycle-wheel wind turbine. I think it;s GE and Siemens who have started limited use of large-diameter, direct-drive, permanent-magnet generators, but not that large. Maybe some use could be found in AWE for such an oversized version but there are also many other choices. You can tell the “SWAY” turbine is (was) going nowhere, with just a quick glance.
1 Like
Hi Doug, the Honeywell rooftop turbine is very heavy compared to its power. But the cause may be the implementation of some “way-too-many-blades bicycle-wheel”, and not the generator by itself.
A large-diameter, flexible, thin and light generator could lead to better AWE architectures.
1 Like
Ignore the construction method for a bit, you are imagining two very large rings on top of one another, one that has magnets and one that has copper windings? And then you want to spin one of the rings?
How many magnets and how many copper windings would you use? Would the magnets/copper cover all of their respective rings or only part of them?
Pierre: Sure, you can make a permanent magnet alternator at any diameter you want, for whatever use you want to put it. Sure a very-large-diameter version “might have” a use in AWE. “Might have” a use for other things too. But also at such a diameter, there are other possibilities. If we take the SWAY as an example, not seeing any indication it was a beneficial solution, in that case. But, good to point it out.
Yes for the two questions.
I don’t yet know, I would choose the lighter solution if it is reliable enough.
To @Windy_Skies and @dougselsam: an example of large-diameter and light generator is given by Dr. Beaujean http://quak-equipment-projects.com/Visualisation/images/RechargeNews2012.pdf. Unfortunately it is only a design, but its (even partial) realization would solve numerous problems that are meet in other AWE schemes.
I will put here some discussions concerning (at least partially) rim driven ring generators as they are related also to the present topic for what I think.
https://forum.awesystems.info/t/state-of-awes-your-opinions/1531/13?u=pierreb
https://forum.awesystems.info/t/state-of-awes-your-opinions/1531/22?u=pierreb
The following link does not represent really a rim driven system but only an inflatable rotor for a HAWT. Perhaps Tensairity ™ could be used for the ring as suggested by @philip.
A main question could be if Tensairity ™ use can allow to build lighter rotors, being able to scale more, not particularly for Daisy, but rather for rim driven generator systems or only inflatable rotors. Some HAWT, AWES, and also AWE / HAWT hybrid systems could be concerned such like ASWES.
A motor has very small tolerances for distance between magnets and coils. So making the size of the motor very large is difficult, even more so if there are blades on it with huge forces.
I think it is quite difficult for someone like me to improve state of the art for motors. An expert will probably be able to select a near optimal design in a short while.
I guess for AWE it is better just to opt for something which is readily available at this point in time.
2 Likes
There are two sorts of rim driven turbines: bicycle-dynamo type (Keuka, Barber Wind Turbines) like on the link below, and when both stator and rotor are adjusted rings (Windtronics Honeywell).
The image of the Winflex turbine must have gotten stuck in my mind a long time back - though I had rather forgotten about it. Rim generation seems a rather difficult proposition for the reasons already cited. My tensairity suggestion wasn’t with any particular configuration in mind - more just in terms of the most scalable technology which seems to be going. But to take the Winflex example, tensairity does allow for a thinner and lighter ring than the pure inflatable torus. I would have thought this would be particularly advantageous in AWES.
Unless you work on a design which exploits the expansion of dynamic blades so as to avoid the need to fight mass scaling of compressive structures…
Daisy is an example. As you explained @Rodread the expansion is obtained by bank angle of the blades and the centrifugal effect. As the latter decreases with increasing diameter, it remains to know what is the maximum possible diameter.
Beside it perhaps Tensairity ™ could facilitate the building of a larger (ring) rotor, but it is not sure.
I just saw a description of a ring style generator for a wind turbine https://www.megawindforce.com/ :
https://www.megawindforce.com/technology/performance
The ring structure acts as both rotor and generator. The design allows an airgap speed of over 25 m/s as opposed to existing direct drive designs, which are limited to 5 m/s. In addition, the generator works at high frequency with adaptive cooling, resulting in a significant 95% weight reduction of the generator.
The flexible and scalable generator starts at a minimum of 2 m/s and increases output up to 25 m/s; output can be optimized per wind area. The generator consists of various scalable units.
More info on:
https://cdn.pes.eu.com/v/20180916/wp-content/uploads/2018/09/PES-W-3-18-MegaWindForce-Talking-Point-1.pdf
What do you think? Is there any possibility for an AWES flygen rotor?
It just looks very large for a generator to me, and I would think quite expensive. To make an educated guess one would have to compare the cost to build vs a traditional windmill. Difficult to say anything more without this. Because otherwise its just a different hawt.
I know the Norwegian startup Sway did something similar, though they did not take it as far, and failed. Maybe not for reasons of the design though, I dont know.
Actually Im not even sure they failed, the company seems to still be alive…
A post was merged into an existing topic: Questions about Moderation
This statement is corroborated on
Beyond this, increasing generator size makes it more and more difficult to guarantee that direct-drive turbines can maintain the size of the air gap, i.e., the radial distance between the generator rotor and stator. Technical solutions require either great care to be taken during component production or a stronger magnetic field, which, in turn, increases the weight and needs more rare-earth elements for the permanent magnets.
This confirms the questioning of A large diameter ring style generator, and also, more generally, some of my topics relying on a large ring generator, such as Beaujean’s AWES as a start for a collaborative project, Rotor surrounding a round kite, a variant from Flettner balloon and VAWT side by side , and perhaps elsewhere.
The sketch, describing a sort of rim drive generators aloft (see also the other sketched variant with rope-drive transmission), could perhaps be an alternative solution (also mentioned here) to the real large diameter ring style generator, avoiding the major drawback when scaling.
An molded raceway from an extremely low friction insulating material
May maybe may hmmm possibly
Provide a potential solution to replacing airgaps and bearing configurations
Caveats galore
Yes, all the configurations are difficult to implement, including this one with rim-driven generators aloft.
Things are far easy when the blades rotate with the inner ring, just like TRPT Daisy, with generator at ground. A variant (which also would be the sequel to the first Daisy design with a buoy as a ring), with helium or hydrogen inflated torus (ballute) carrying the blades, is described, allowing to scale in range and in diameter: Rotary ballute-based kite.
1 Like