Kite Turbines
windswept-and-interesting.co.uk
windswept-and-interesting.co.uk
Flying things need to be lightweight.
Electrical generators are heavy.
Makani: Ok I will build a flying generator ... :thinking:
Related Keywords:
- Airborne wind energy (AWE) (the name of the field)
- Fly-gen (mechanical to electrical conversion happens in the sky)
- Ground-gen (mechanical to electrical conversion happens on the ground)
Other resources worth of attention:
- On the edge, possibly near to commercialization: https://www.ampyxpower.com, ...
- Commercial solutions: https://thekitepower.com/, ...
- Project similar to the one linked (rigid wing): https://www.someawe.org, it also have a nice conceptual map style overview of the field https://www.someawe.org/awe-map-the-someaweorg-airborne-wind...
- Forum with knowledgeable people on AWE: https://forum.awesystems.info/
> - On the edge, possibly near to commercialization: https://www.ampyxpower.com
A CGI video does not convince me that they're near to commercialization.
"possibly near to commercialization"->"they have something flying"
Many others should be mentioned, i.e. https://www.kitemill.com/
[Former Makani software engineer, here. I wasn't involved in the early stuff, or the design trades, but I heard a lot about it.]
I am curious, do you know why Makani went 100% 'fly-gen'? From by biased point of view I would say that it was easier to bootstrap (more control agency, easier take off and landing) but harder to scale.
I tried to skim through the 1k+ pages 3 part report available from Makani (https://x.company/projects/makani/), but it doesn't seem to speak much about the considerations which when into that early design choice. Do you know more?
Is it possible to summarize them or it's an organic set of reasons which cannot be untangled nor simplified like often happen when dealing with complex systems?
[Mechanical Engineer here]
As to fly-gen, it has several benefits, like continuous power delivery and not least an easy way to launch and land - you already have the propellers.
The main downsides are complexity, weight, and the weight and girth of the tether needed to transfer the power. The drag from the tether is significant. Plus the sound of the blades.
As an example, Makani's Y-bridle design to attach the tether to the kite introduce stability issues during hover, and limited their control when the kite was aloft making circles, which in turn limited their power generation.
It's quite possible that if their kiteplane was much lighter that these tether issues would have been much less of a problem. Remember that the Makani tether also had to include some copper cable for power transmission to the ground. That makes the tether itself heavy as well.
Way less logic and parts needed vs Makani
Compared to this project that's essentially a few rings and a bike transmission.
My guess is that except in some specific applications like winter use in polar regions, solar power will end up producing more energy for the same investment over time.
Cheap solar is hard to beat, and the new printable panels promise to make it even harder.
Solar is just a lot of energy compared it to kinetic sources. It’s counterintuitive.
A typical single solar cell from a panel (5 watts) does the work of lifting a 5kg weight 300m high every hour. It’s kinda mind blowing.
Power is the movement of energy over time, measurable in joules per second, or watts. Moving 14700 joules in 1 hour = 3600 seconds represents 14700 J / 3600 s = 4 watts of power.
Or energy generation at night and in cloudy areas.
They assemble it themselves. They make the control board mostly themselves, apart from the PCB which is made in China. They also produce the plastic (molded resin I think) and metal parts (we have a big CNC mill) themselves, so they can handle low production volumes without a big upfront investment.
They recently tested it on the Brittany coast under heavy winds, it did fine. It was tested a lot on Aquitaine coast.
I think these will be very appealing for campers, off-grid, emergency and other backup situations when they can hit a somewhat lower price. I understand solar panel costs are dropping, but it isn't always sunny everywhere!
I work in infrastructure management. This might be a good solution for site power roadside or trackside.
> Kites like Makani's are autonomous
They wrote
> Makani's kite is steered. This one just needs to stay aloft
The implication is that you are suggesting that autonomous steering is neat and the other person is suggesting that not needing steering is neater.
Also, Makani was steered into the ground literally and figuratively. It's been cancelled. It will never do what it said it could do because its creators won't keep doing it. It's over.
I'm simply agreeing with the guy that said that launching is expensive. It's indeed the hardest part for any kite energy system, I know this from experience, I spent several years in this industry.
If you could live with having to launch and land the system manually, that would change the equation completely.
The are also cancelled, gone, don't exist, will never happen
> Kite turbines can fly under 30m above ground - making them the only CAA ANO CAP393 compliant airborne wind energy system.
There are very sound reasons for wanting to get your energe extraction farther from the ground.
https://support.google.com/youtube/answer/171780 (and look at the “Turn on privacy-enhanced mode” section)
- https://medium.com/kitekraft/kitekraft-takes-off-with-y-comb...
With some sturdy ground stakes to pin his upside-down bike the ground, this could make a neat source of power when your off-bike, in the field. What’s the smallest possible clone of this that you could bike-camp with, I wonder?
Even hobbyist kites can become quite scary when the wind gets stronger. I don't want to be hit on the head by a kite turbine in strong winds.
Potential for damage and energy are probably correlated, in the sense that this design seems to attempt to harvest low-altitude winds (30m), while makani and others wanted to get the high-altitude stronger and more constant ones.
This design does not have an heavy high flying turbine, it has a small lightweight one, and they plan to have multiple tethering ropes so I think the risk you face is in fact in the same ballpark as a hobbyist kite.
IANA wind-electricity-physics person tho, so take everything I say with a large grain of salt.
https://media.wired.co.uk/photos/606da5dc581351b2c44d7d4c/ma...
The idea with kite energy (in serious projects) is to eliminate the need for a tower and the inner parts of the blades.
The kites can be seen as the tip of the blades, which is where almost all the energy is generated.
Kite energy can dispense with the tower because they are tethered with a largely horizontal cable, so there is no lever involved and the foundation can be much smaller. You could sort of do that with the flying turbines, but that wouldn't really work in a city environment.
Let's suppose out at sea each peak to trough is 60cm and the movement up and down causes the internal dynamo to be driven by 30cm for each one - you probably need two lines into each one, positive and negative serially and you could get a pretty good average amount of electricity probably.
No idea if it would work or the output would be too uneven but there is a lot of sea and it seems a bit easier to build and repair than something that sits statically in the water.
The bird death argument is completely meaningless in several aspects. I'd rather make cats illegal than put any kind of breaks on wind power expansion.
In any case, those are probably just napkin calculations. And I bet I can find a wild variety of estimates for birds killed by wind turbines, too - depending on whether the person doing the estimating wants turbines to succeed or not.
It seems likely they don't kill the same birds as wind turbines, either. And not in the same locations.
All in all the comparison might just make not much sense to begin with.
How many birds are being killed and eaten by humans, for example? Probably several billions more, but they are not the same birds that are being killed by turbines.
Well, once every 6-ish hours. But even then, you put the turbine on an axle to turn it into the flow. Windmills have been doing this for centuries.
Actually, yes, that would indeed be a good use of the concept - anchor the generator to a submerged bouey (so as to not disturb shipping) and it will always be pointing in the right direction and generating. Nice!
A kite isn’t the only way to do this, could alt be; some kind of semirigid textile mushroom; suspended between buildings or across a chasm; integrated into a built structure; an inflatable; an aerostat; and so forth.
For small scale energy production small VAWTs [0] are relatively cheap, they offer more W/m2, and they are much more easily serviceable and installable.
For large scale production it's orders of magnitude less efficient, plus having multiple kites on the same plane brings in the wake effect [1] in full force. That's why regular turbines are generally laid in lines rather than wide surfaces, or with significant separation between them.
[0] https://en.wikipedia.org/wiki/Vertical-axis_wind_turbine
[1] https://youtu.be/qd_hEja6bzE?t=392
Regarding the size x quantity, I believe the reason lies in where the best wind is, which is usually high above the ground. The roughness of the terrain and obstacles generate shear and turbulence, which translates into more stress for the components. The higher wind has a more uniform distribution across the rotor and is higher in magnitude than in lower heights. So for small wind turbines to have access to the best wind, you would have to build expensive structures to reach there, making it infeasible. Hence kite approaches like the one posted and Makani (with different principles).
Higher winds are much more stable. Both in having less completely still days, and having the median be much closer to the maximum. A wind turbine that is built big enough starts having a large part of it outbut be effectively baseload instead of intermittent, and as more renewables are built out, baseload capacity is increasingly more valuable than intermittent.
1.5KW is nice but guaranteed 30mph constant wind?
- Add a lifting balloon a the end
- Add mini lifting kites to each ring. Tether it to a point above the earth so the first ring will always have some mini-kites in the wind.