I didn’t think Doug included aerostats as a possibility.
One “simple” way is to use an aerostat to suspend a wind turbine as suggested above. Although this simple way would be likely preferable because the load is settled at the usual place under the aerostat, I mention a variant and another way for dreamers like me, just below.
And Tallak said:
“I didn’t think Doug included aerostats as a possibility.”
OK HERE is what I thought as the AWE sector and all of these “even-more-crazy-than-usual” wannabe wind energy “inventors” emerged:
These people know NOTHING about wind energy
These people know nothing about inventing
Inventing doesn’t mean you have to re-invent every component (such as Dabiri re-re-inventing the vertical-axis turbine to place below real turbines, Altaeros trying to re-invent the aerostat, Minesto, Magenn, and the “million flies” trying to re-invent the rotor (or its supposed equivalent), etc. Inventing means standing on the shoulders of the giants that have come before you - use proven components in new combinations, and it doesn;t have to be that complicated! Why not use the best type of turbine Dabiri??? Why use a proven crappy design? Why not use a proven Aerostat Altaeros? What the heck is the matter with these people? Has “Professor Crackpot” taken over their brains???
The first, simplest, most obvious things to try would be simply lofting a turbine using a kite OR an aerostat. Nobody could be bothered!!! After all these years, pretty-much nobody has made a decent effort of trying the two simplest ideas for AWE!!!
Wind Energy is a magnet for Crackpots. Airborne Wind Energy is a neodymium supermagnet. At least the old style of wind energy crackpots, however misguided (usually chasing vertical-axis designs) knew something about wind turbines…
Their problem was not realizing how bad the math is on vertical-axis turbines, thinking the real reason nobody uses V_A machines was because it just needed their “special” input, normally throwing away the first stated advantage of not having to aim, in order to provide pitch control.
Today, ANY crazy idea is taken seriously! Like flying airplanes between turbines to mix up the air or whatever that one was - people have lost their minds. There is no requirement for anything to even pretend to make any sense! It;s just “land of the lost” or maybe “crackpot city!”
Having said all that, like any wind energy inventor, I do have some vertical-axis ideas myself…
Hello Pierre:
Very interesting that you’ve found a brand new proposed design, after all these years, to hang a wind turbine(s) from a blimp. Funny how much it resembles Orbital Marine. As far as Pacific Sky Power and Kitewinder, notice I DID say “a decent effort”. I don’t think an idea and some renderings, so far, quite constitute “a decent effort”. So far it’s just an idea. Looks like a good idea, but at this point it has not been built or run.
Now I’m not saying Dan Tracy and Kitewinder didn’t contribute anything, but neither is much more than a toy. Toys are a good start, but still just toys. And Kitewinder could have just placed a generator up there instead of a custom-made gearbox and cable drive. This is what I mean when I say nobody can even do the simplest thing. They usually want to make it more complicated! Or they put forth a minimal effort, such as loft a teeny electric motor with a model airplane propeller and call it a wind turbine. At least that showed it can be done, but can it even charge a phone? Not so sure…
A time more, kites lifting a turbine has be realized in small scale. The results have not led to any larger-scale projects. And understandably so: a wind turbine is heavy and generates a lot of drag. So you need a very large kite to lift it. For an aerostat, it’s even worse: you need helium, which is rare and expensive, and you have to top it up regularly because of the porosity of the envelope.
OK well, first of all, nobody has demonstrated a decent turbine lofted by a kite or a blimp, and you don;t need to call them “my” ideas - they are simply the most basic AWE concepts, and they remain unexplored.
You can’t say Dan Tracy proved or disproved the concept of a kite lofting a turbine. All Dan proved was that it was at least possible, which was never in question anyway. So you can cite “reasons” why it could never work out, but the fact is, nobody has made a decent effort.
And your statement about helium has been stated many times by one of the people associated with the old forum, where he roundly and relentlessly derided me for “wasting helium” with a demo that used a few tanks, meanwhile there is a world market for helium, with more constantly being produced, AND other choices which you often cite, such as “hot air”, which would not be my choice, but also hydrogen, as in the PDF file of the blimp with two turbines hanging on arms that you provided earlier today, and another choice that nobody talks about: methane, which is something like half the weight of air. Why doesn’t anyone know that methane is lighter than air? Because nobody talks about it so nobody knows.
But again, nobody has tried any of these. A blimp or airship does generate aerodynamic lift in a wind, due to its angle of attack alone, and wings could be added to bring more lift. But that’s getting more complicated. To me, the whole progression of AWE, beginning with Magenn, Makani, and Altaeros, has been mostly ridiculous, (especially Magenn and Altaeros) and meanwhile, nobody could be bothered to just hang a wind turbine from a kite or blimp. That included you, who placed a Dan-Tracy-esque Model-airplane propeller driving an electric motor as a generator, into a hole in a kite. OK so you both started with a bad rotor, just to begin with. Again, like so many wannabe inventors, you had to add one more feature to screw it up, rather than just elevating a wind turbine by hanging it from a kite. And like Pacific Sky Power, you showed it was possible, but did not produce a prototype of sufficient quality to prove much, beyond the fact that it could be done, which is a good start, but doesn’t really answer any questions. Neither has led to any universally-recognized go/no-go decisions on whether to build a better one.
So I will go back to my previous assertion, that nobody purporting to be involved with AWE can be bothered to try a decent version of even the most basic AWE concepts.
You forget that FlygenKite can fly both in crosswind flight and in static flight (as shown in the video). And in static flight it is simply a kite lifting a small wind turbine. And that produces what the rotor sweeps, which is almost nothing. In crosswind flight this produces much more. This is the reason why most companies choose the crosswind flight.
Like many newbies, you criticize other projects while your two simplest ideas (one of which I tested) cannot be profitable, which a schoolchild can understand.
Pierre: Everyone here knows very well why AWE projects tend to use cosswind travel: to increase the apparent windspeed. That’s the whole point I’ve been trying to make, Nobody has bothered to try a non-crosswind kite to simply lift a flygen turbine. Possibly everyone understands what I mean except you. And I’m pretty sure you understand too, but just have too much time on your hands and would like to try to keep coming up with “arguments” that you think “sound good”, but make little sense.
Meanwhile, your model airplane propeller running backwards attempting to imitate a wind turbine rotor did not hang down perpendicular to the wind, but was instead oriented parallel to the fabric of the kite. It also suffered from a way-too-low Reynolds number to function very effectively. So, running backwards, not perpendicular to the wind, and a low Reynolds number - a nice demo perhaps, but not sufficient to verify or disprove the concept of a wind turbine suspended from a kite in general. So I will stand by my previous assertion that nobody in AWE has bothered to effectively test the two most basic AWE concepts. So I think you should stop calling these two concepts “my concepts” and stop pretending you tested one of them, which you did not. You did not test a wind turbine suspended from a kite, you tested a (very rudimentary) turbine EMBEDDED in a kite surface, and those are two completely different concepts.
Pierre: OK you are right, I did not watch the video, and I guess I forgot you did also try a “turbine” hanging from a kite, in addition to the one I remembered, which was a turbine embedded in the fabric of a kite. Sorry for my occasionally poor memory. However, due to the backwards model airplane propeller configuration, a person with wind energy experience would already know to expect extremely low performance in ambient winds, due, as you say, to the small swept area, but also due to being run backwards, and the low Reynolds number with such a small size AND being limited to the ambient windspeed. A bigger turbine with real wind turbine blades might have given better results. So, while your flygenkite was a decent effort at a quick demo, I do not see that it was sufficient to disprove the basic idea of a turbine lifted by a kite.
And yes of course Kitewinder did a decent job of demonstrating a ROTOR lifted by a kite, but did not include a “flygen” generator, but instead had to add an unnecessary additional “invention” (grandma’s clothesline) and make it far more complicated than necessary. At that point, just ask yourself, if it was worth testing with grandma’s clothesline and all that gearing, and it did make some useful amount of power, why would it not be worth testing using a flygen generator? To me, if they showed anything, it is that hanging a turbine rotor from a kite could work at least OK for some uses, suggesting that a complete turbine with generator, hung from a kite or blimp, might find some use. But nobody has done a sufficiently decent job of building one to realistically test the concept.
So I’m still of the mindset that the two simplest AWE concepts remain basically untested.
Moreover the question is not the efficiency of this propeller or another rotor, but between the same propeller or rotor in both static and crosswind flight: the last is about ten times more efficient. Listen to the difference of sound between static and crosswind flight.
A “flygen” generator (slow rpm due to static flight, so high weight) + the electric cable are far heavier than the rope drive transmission and the pulley aloft. So @Kitewinder 's choice was relevant, and their AWES works.
To come back to the topic, an aerostat with 1000 kg payload capacity is extremely expensive compared to the low scale of the wind turbine aloft. Helium is very expensive, and everybody knows methane, ammonia, hydrogen, but nobody uses them.
Pierre, a nice as your quickie demo was, it didn’t disprove hanging a wind turbine from a non-moving kite. You cannot reasonably pretend a model airplane propeller running backwards serves as a realistic imitation of a real, dedicated wind turbine rotor. At best, I could have told you that the only way to get any power out of it is to force-feed it with a high-velocity flow. The fact that it does next-to-nothing in an ambient wind is to be expected. That fact that you can force-feed it a high-velocity wind and light an LED is also to be expected. And I believe that for the 100-150 Watts Kitewinder was delivering, a generator at least as lightweight as their more complicated geared setup could have easily been substituted.
Therefore, I do not accept your offer of “proof” that a simple kite lifting a turbine could not work or have a use. Tinkering and playing around with kites and model airplane propellers is all well and good, far better than doing nothing, but let’s not pretend it is sufficient to prove what real, dedicated wind energy components could be capable of.
Anyway, my point was nobody has done a sufficient job of even trying what AWE purported to be all about: eliminating the tower. A stationary kite or blimp could lift a flygen turbine. And nobody has built or run such a setup at a level of quality to say whether it might have any place in AWE.
You buy a wind turbine like this or that, then and you hang it on a kite of the corresponding size, or a blimp like TARS as mentioned on this topic, or even a helium inflated shapewave®Sharp rotor.
@dougselsam often says that the simplest way to achieve AWE has not been studied enough. He has some good points to argue with. There are also drawbacks.
Expected advantages:
Both wind turbine and kite are proven technologies
Simple and continuous operation
Possibility of a high elevation angle
Possibility of a higher density in a farm of unities (?)
Main drawbacks:
High weight / power ratio
Requirement of an electric tether
Pendulum effect of the turbine swinging under the kite
Hi Doug, the problem is the weight and drag of the wind turbine.
Net weight of G10K (10 kW, diameter 6.5 m): 215 kg.
Kiwee includes a 4 m² kite to lift the rotor sweeping about 1 m², and the pulley transmission, the whole weighing 1-1.5 kg.
So for 215 kg (and related drag of the wind turbine sweeping 33 m²), an approximately 200-400 m² kite (or a 300 m³ blimp) would be required, and for only 10 kW.
By using only a 300 m² crosswind kite in reeling mode, the average power would be more than ten times greater.
