Why does AWE have to compete directly with traditional wind turbines? Why not for example look for a market where traditional wind turbines is not able to exist, or are to costly to install?
For example traditional wind turbines needs roads to be made to where they are placed for the big semi-trailer trucks to be able to drive the tower, nacelle and blades to be assembled. While helicopter transport is limited in weight and is expensive. So why not AWE with its smaller components on locations like mountaintops, or in terrain where roads can not be constructed for traditional wind turbines? It can even be sold to local politicians as less destructive for the nature because you can ship it in with a helicopter so you dont have to make roads trough the terrain.
The AWE companies made the more difficult choice in attempting to implement crosswind AWES, hoping that eventually they could produce on a large scale and at high altitude as planned by investors and scientists such as Cristina L.Archer.
This way looks to be feasible but should take a long time. More simply controlled devices like Kiwee or some other rotating devices (like this) could catch some market niche by waiting.
It is true that AWE could open up new wind resources. Even so, we must remember that electric power is transported super cheaply and without much loss. So for any larger grid, that means other solar, HAWT wind and nuclear resources must be depleted before one would choose to build more costly AWE.
I think perhaps one may consider paying more for more nature friendly AWE, in particular if this is built offshore, where interference with humans is small and wind is strong. But I believe these things are a bit early to plan as we dont know yet exactly what AWE will look like
Not sure thatās their default prime directiveā¦
If sustainability were more closely linked to commercial viability then massive onshore wind farm projects like we have here Would be much less profitable. The amount of peat being removed is concerning, And the electricity is mostly going to make oil extraction more green.
Sinking anchors into the peat instead of roads, tower bases etc ā¦ yeah, makes sense
Wind energy is intermittent and depend to carbon energies such like gas, oil, coal, leading to a poor carbon footprint. See the example of Germany.
Thus the chances of success of AWE are minimal because it does not (or not yet) solve intermittency problems, adding also new issues. We are still at debates of the type āhow should we hang the tetherā, interesting from a technical point of view, but far from the energy concerns of the moment.
AWE is for niche market at the best, not more, at least for the next decades.
So why are companies trying to compete with traditional wind turbines? Why not just go for the niche applications and be happy with that? At least as a beginning.
As an example for tourist sites on mountaintops and sites like that where you dont want to install big wind turbines, and you dont want to install big powerlines that ruin the landscape visually for the tourists. But you want power for a restaurant or tings like that. Then you can for example in addition to installing solar panels on the roof of the restaurant building add a small AWE system in a box that can run when there is wind in the nighttime or on the low season when tourists are not annoyed by the kite flying and use this in addition to some energy storage to power the restaurant.
Both your and Pierreās statements are not substantiated adequately. You could visit the websites of any company you are interested in to see their public plans. IIRC several are going for niche markets.
Sure, I tried to summarize the situation in a few lines. For utility-scale AWE, decades are not a so large time in energy evolution. And niche markets can be significant.
Some companies such like Ampyx plan utility scale. Some other are going for supplying remote locations. This last goal looks like a deviation from the first goal. Likewise, the goals of harnessing high altitude winds are revised downwards.
AWE players are slowly realizing that AWES are not ready for large-scale production. Makaniās experience could confirm it.
So my complete sentence can be supported, even if the future is not still known:
True, but Makani, KiteKRAFT and Windlift use secondary rotors. Part II, page 20, the weight of the rotors and spinners is 65 kg, so a low weight compared to the whole M600. The power was rather high (but unequal during the loop) from 12 m/s wind speed. Unfortunately we donāt know their lifetime due to crashes.
Not sure if you are including the generator in that weight. There are many tricks that can reduce generator weight. For tower-mounted turbines I like the generators heavy. They get beaten up pretty bad and being heavy helps them survive. Then again, the 10 kW turbines we have here (a different brand, not ones I built) weigh about a half ton. Too much weight for a mere 10 kW in my book.
One point: You can get many times the rated sustained power out of a generator for brief bursts, but there is a runaway heating effect that will toast the stator if the high power is continued for very long. Even if the generator survives one episode of excessive power generation, the insulation on the windings will be damaged a little bit every time it happens, shortening its life. There are tables where you can look up how long you can expect your windings to last depending how hot they get.
Looking at the title of this thread, I thought it had been determined over a decade ago by the finest minds, that AWE is commercially viable. They were going to quickly replace all those stupid tower-mounted thingys ruining the landscape, remember? And saving the cost of the tower was the main reason, right?
It has very well argued methods of calculation. The calculations demonstrate a lot of the complexity and breadth of field @PierreB was looking for in this thread.
However only pump & drag AWES schema are factored.
Very exciting reading
Must get back to reading itā¦
Hi Pierre:
I remember discussions like this many years ago, before AWE. One turbine designer said if you can keep rotating machinery below 800 RPM for sustained output, it will last forever. He was talking about steam engines, diesel, etc. The generators I build are designed with a top end around 800 RPM even though you can go much higher for short durations,. Iāve still burned out a lot of them in sustained high winds. Not easy to keep that RPM down in a horrendous wind, where they can even overspeed running sideways. Seems like you can run them a long time, but when you get high winds that go on for hour after hour after hour, youād better have your overspeed system perfected. Once a generator starts getting hot, the resistance in the windings increases, which causes more heating, and that just gets worse as time goes on, until things start smoking. Typically you need many systems in many locations before you begin to see the patterns of failure, By that point you may have a certified design that has inertia from a business and production standpoint. This is one reason so many of the small wind turbine companies have gone bankrupt in the last few years. Iāve seen instances where a company should see what is wrong with a given model, with a reasonable fix being observable, yet they just go on selling more as warranty returns pile up in a warehouse.
Hi Doug, thanks for the information. Do you think a generator like on Makaniās secondary turbine or the link below (this is a motor but perhaps it could work as a generator), rotating at about 2000-4000 RPM, could have a long lifetime. A brushless motor for model airplane is expected to have a very long lifetime, but I donāt know if it is really true, and I donāt know if it would be the same as generator. https://www.aeroexpo.online/prod/mgm-compro/product-171210-63386.html
The alternator on a 3600 RPM Diesel generator spins twice as fast so it can get by with less than half of the copper of an 1800 RPM alternator. Due to the higher engine speed, these 3600 RPM generators wear out much sooner.
That can confirm your previous indications @dougselsam.
So it is possible to deduce that the lifetime of generators settled in secondary turbines can be lower due to its high rpm. That said some other parameters (whose the way of use) should be taken into account.
5 kW/kg, so 120 kg for 600 kW motors/generators, in addition to M600 airframe: rotors and spinners = 65 kg (page 20), so 185 kg. Adding (see page 47):
1700V SiC MOSFET design
ā SVPWM @ fSW = 10 kHz
ā Liquid cooling plate
ā 1 kHz comms loop to facilitate stacking
stability
ā Has passed significant rel and
environmental testing
ā 7 kg each
Besides it, I believe that AWES will be able to be competitive in a few decades, the required time when nuclear energy will had partially mitigated global warming, and when the intermittence is resolved by appropriate storage.
Iād say the reverse might be more true: 5 kg / kW, if you want the generator to produce steady power in high winds for hours on end. Windy areas are often way way windy than optimal for just making power, but you have to deal with those days. My generators weigh twice that when I rate them realistically for continuous hours of high-wind-torture. I could make them quite a bit lighter if I wanted them to fly. Just about everything works great in fair weather. Itās the nasty stuff that destroys turbines. Then again a lot of wind turbine companies went bankrupt due to failures even in just good, productive winds.
