The initial idea was how to harness consistent and powerful high altitude wind. Sky Windpower (https://skywindpower.com/) has built one of the first prototypes. The purpose was harnessing high level jet streams. Then, for some AWE companies, the tethers were shortening, the purpose being harnessing low level jet streams (LLJ), then yet below. In some way the main purpose became different: using less material, then a nomadic device, that due to difficulties by using long tethers (land and space use, drag, weight…).
Kiwee is a simple (not crosswind) and efficient small device on the market, flying at a high elevation angle. It does not reach LLJ but an altitude that can be seen as high in regard to its size and to competing ground turbines, so the advantage of harnessing more consistent and powerful winds also applies.
Things are a little different with some torque based and crosswind kite devices, all flying with a low elevation angle (30-35°): the expecting benefit may be limited to the use of nomadic and light equipment. But the advantage can be significant in regard to an expected high power, and a possible use onshore and offshore.
Torque-based turbines like SuperTurbine ™ or @someAWE_cb’s, or comprising TRPT like Daisy or perhaps rotating reel, could be improved (electronics and other) then marketed as low altitude (below 50 m) devices.
Crosswind kites (@Kitepower, @katieschaef, @tallakt’s Kitemill…) could also be marketed before reaching high altitude winds for the same purpose as previously indicated, by using a short tether of only 100 m. In the same time the proportions between the tether length and the swept area would be more harmonious, knowing a kite in the end of 1 km tether should be quite huge to produce enough power to compensate the high space use.
To resume, there are some possible markets for AWES now, but not yet for the absolute high altitude winds.
You are right pierre, that is the difference between dreams and reality. Natural innovation scheme goes from simple things to more complex things. That being said, it seems normal to start with low altitude winds and gain height with time , experience and users feedback.
Regarding kiwee, if it goes up to around 50 meters, it is because main pulley and drum are the same part, that limit the quantity of rope drive you can handle. There is no technical problem to go higher except more line is more cost… But if our customers want to beat some records, they can put a longer rope drive and store it in another drum. that will only cut off the reel in automation but work exactly the same. On our next product, we will aim 600 meters ( rope drive of around 1500 meters long ) because the product will be bigger, and pulley and drum will be dissociated. It is ok to say kiwee is a simple product. that means we worked well but trust me, we sweat a lot on it, especially on blades for example, took us maybe 500 iteration to get a correct production process.
Olivier, I want mean this is a simple device within a complex field. So it is not surprising that such a device requires a huge work, moreover knowing it is commercialized.
The endless handwringing and lack of action in wannabe AWE.
Paralysis by analysis.
Which happened first, Robert Goddard experimenting with small rockets, or the moon landing?
If you encounter a stairway or hill, assuming you barely know how to walk, do you start climbing from the bottom, or do you try to jump all the way to the top on the first try?
Do you start school in kindergarten / first grade, or at a post-graduate level?
By the way, what happened to Cristina Archer, our “denmother” (a term from Cub Scouts) of ten years ago, who served to confirm for the unwashed neophytes that, yes Virginia, there is wind up there. I think we then had to listen to a couple years of “experts” seemingly fixated on their fun new vocabulary word “low level jets”. None of them ever came up with anything to harness even these “low-hanging-fruit” LLJ’s)
Well, experts, where have you taken all this information during the last decade?
NOWHERE.
The conversation has barely changed.
High or low? Skygen? Flygen? Groundgen? Ahhh those were the days, when people who know nothing about wind energy to begin with, could nonetheless pretend to be “experts” with their fun, new, vocabulary words and occasional “mascots” sporting PhD’s. I remember thinking, “if you need a PhD to tell you there is wind up there you are really new at this”. Oh well, it was fun for them at the time, and all they really had, so…
Let’s review:
Wind is faster the higher you go, up to a few miles, but the air is thinner too.
You can do AWE at any height that works for your technology.
The question is, as usual, do you have a device that is useful for any purpose, at any height?
There, did I miss anything?
I think AWE could be useful at very short tethers (drag of tether much less than drag of a very efficient blade), medium tethers (balance of drag in blade and tether) and long tethers.
The medium is what we are seing now, with rotary being closer to «short» due to torque transfer. I think we might see short tether lift/drag mode awe rigs.
The thinking is: perhaps going high altitude is not the most important thing, even if at first it seems an obvious goal. Just getting rid of the tower might be enough to make AWE worthwhile. If these designs succeed they will with some probability not scale well to high altitude without a redesign (meaning that a second evolutionary leap is necessary to get to high altitude AWE).
For the last category, high altitude, like in utilizing jet streams, I dont think we see a lot of potentially good designs around yet. As a start, the tether must not be moving much. So we would immediately need more than one blade in order to still move crosswind and still keep the tether immovable. Second, if the tether is long enough, you will need pretty constant tension. This would probably mean conductive tethers or very long yoyo production cycles.
To be honest, right now I don’t see how this would be economically feasible. I’d love to be proven wrong on this though.
In the meantime, I’d put my money on either medium or short tether AWE.
Oh, I forgot the option that the medium length tether rig could become high altitude by «brute scaling». I guess we are talking 10-50 MW scale here. This may come by evolution, but maybe some hurdles will stop this evolution before we reach this scale
What has become clear is an ideal convergence between Cristina and Wayne’s LLJ wind velocity enhancement, nicely centered on the best of the FAA’s AWE airspace allotment (<2000ft).
Therefore 500m high is the current sweet spot for serious AWES developers; superior wind, well above wind towers, and under major aviation traffic.
Its definitely still very premature to go after market-rate production. AWE remains a pioneering R&D race until about 2030, with plenty of early investment capital in the pipe.
The 2030 timeframe is based on a Critical Path Analysis done in collaboration with WoW in 2011, led by Carlo Pedrassi, PE (Old Forum). The same rough timeframe has been lately identified by third-party Maritime Engineering analysts (Old Forum). ~2030 is also consistent with the historic pace of aerospace “revolutions”, and industrial engineering innovation generally.
If you have any better prediction basis, please share.
The 2030 timeframe is sourced to WoW and the Maritime Engineering web site previously cited on the Old Forum. I looked in the archive, and many related messages are there to be found. Many of us are also aware of premature AWE utility market entry estimates, that have come and gone. Let time finally tell whose written predictions prove closest to reality, or just “blablabla”.
This is an original 2011 CPA plot pointing toward the 2030 timeframe. Yes its crude, because peak-power-claim data was scant, but new data-points since seem roughly on-track, and at least we were trying our best, and we were not part of the many “premature” predictions by other ventures.
Seems to me Makani has been going to power the grid in Hawaii “next year” for about a decade now. IDTechExec or whatever they are called - you know - that guy? Dr.Whaatever? (Professor you-know-who?) _wait Peter… Peter… Harrop Dr. Peter Haarrop’s group - I believe they said last year there would be a 100 kW AWE system available for purchase as an AWE product on the market by 2019. One more example of non-wind-energy-experts knowing nothing - the more credentials, the sillier they sound. From what I see, I think the following rule of thumb applies: If you have people paying you lots of money on the basis of buying either your exciting confidential report or stock in your company, maybe some grants, and you do have at least something making some power, it will always be “next year”. That just sounds good and explains why you don’t have anything overwhelming enough to buy right now but there is still hope. For people who are big fans, but don’t have anything really even in development, saying “ten years” lets them go on forever posturing, never developing anything. I feel that WOW and the Italian stuff I’ve seen falls into that category - in ten more years they can just say “Well we were a bit optimistic - now we think it’s really ten more years”, etc. There should be laugh track here somewhere. It’s already been like 12 years since this whole hype-cycle started. I think Makani started before 2007 and I built the Sky Serpent at the request of Popular Sciece Magazine in 2008 https://www.popsci.com/scitech/article/2008-05/ten-times-turbine/
I believe Dave is saying that the altitude of LLJ happily matches the altitude of FAA’s possibly allowed airspace for AWE (below 2000 ft).
For the second question Dave can mean that torque-based systems like TRPT or central shaft driving AWES will grow until reaching these 2000 ft for 2030, so by 200 ft each year.
An altitude of 500 m is a reasonable purpose, allowing matching both LLJ and FAA’s limit of allowed airspace for AWES.
Predicting a date is premature, especially as the viability of the AWES is far from proven. At utility-scale the AWES should produce more than ground-based wind turbines, and especially since the secondary uses are difficult to achieve, excepted if the AWES is at the same time a fishing boat or a tractor.
As the density of wind turbines is roughly 8 MW / km², an AWES with one km tether will occupy at least 4 km² by counting the safety zone. So a system of less than 50 MW will not be profitable. If this purpose cannot be reached, AWES will be limited to tiny niche markets.
So it is not bad to begin small (by commercialize or not), knowing what is the aim at the end…
And also during the development of the AWES, the wind turbines may have already reached this height of 500 m. If this possibility is achieved there will remain crumbs for AWES.
At start awes will not be about utility scale nor competing with classical utility scale wind turbine. Each time a team try to achieve this goal, they just end failing miserably.
Many teams have focused on an equation that says : hey it is OK to produce cheaper than mature large scale WT. Such a nonsense.
Hopefully, most team has integrated this fact now, except maybe ampyx which I predict taugh time to come.
Awes will be about mobility and decreasing battery cycling on off grid market.
Have a look at how every team is now pivoting.
Let’s be pragmatic.
However you reason about this, the FAA is my smallest concern. Do they really have the influence and incentive to stop AWE? No, it’s pretty easy to draw some lines on a map and raise the minimum altitude some distance. Mind you, someone will have to do the job of getting this realized, if the need comes. But it would be far from a defining factor for AWE viability and timescale.
For utility scale AWE, I’m afraid it may be the only viable option in the long run. Why? Because diesel generators are cheap enough and very easy to deal with. As long as we’re talking small power niche markets, the environmental cost is no big deal either (and theres always bio fuels).
If this turns out to be true, the path for AWE will be proving that AWE is viable through hours of production time at a loss. After this has happened, investors could propel an actor from small scale to bigger scale where it would be cost effective.
I’m not too worried about losing some $ at smaller scale. As long as the sensible calculations show profitability at scale.
And it doesnt have to be the best option for any wind resource. Wind resources are scarce, and each site is different. AWE only needs to be the best option for some sites. I guess I am in agreement with Makani here at some level, putting their efforts into deep ocean wind, where traditional windmills are not a competitor for technical reasons. Another option could be for wind power near populations, for less noise and visual disturbances.
The gradient wind is far lower offshore. So using AWES would lead to a minor benefit. Then traditional wind turbines can reach any place by using float rigs. Then I am curious to know the real efficiency of M600 given the loss by cosine, by erratic power, by brake of the secondary turbines. Adding the control of flight, takeoff, recovery, maintenance…, in a very hard environment. So the chances of success of such a project are between very low and zero.
Less noise by using Makani’s wings with secondary turbines, or even some other power kites at MW scale, with periodic reel-in noise? No imho.
Less visual disturbances with an equivalent power by using huge power kites going fast in all directions, with their mobile 1 km illuminated tethers? No imho.
In the other hand more risks with kites weighing tons going fast in the end of 1 km hugely tensioned tethers? Yes imho.
I am curious to have your opinion on ampyx. When I see their launching offshore platform I just can believe in it. Seemsto be a really ultra complex thing.
It’s great to see that there is not a mainstream opinion on tech and market for now. Hopefully it will converge at some point
About 500 tons for their launching offshore platform. It is less than for a conventional wind turbine, but not much less. The force tilting the rig is measured from the bottom of the sea, not from the surface.
Indeed the launching way is very complex. And ships must avoid the unities during landing or takeoff, or go close to the rigs due to the low elevation angle (30-35° for a crosswind kite).
