Generate energy with kites
kitex.tech
kitex.tech
http://www.newyorker.com/magazine/2013/05/20/inherit-the-win...
Edit: removed unsourced claim about the future.
I wrote a thesis ten years ago which examined the engineering and economics of a more simple kite/glider pair system. Aerodynamically, it can be stable and self-correcting, which I modelled and prototyped, but this may not be an optimal design and launching is hard due to lower (and different direction) ground wind and boundary layer issues.
The drone-like addition adds control complexity, but appears to ease take-off and can probably reduce strain in flight and improve efficiency, despite the aerodynamic cost.
Tower wind turbines have enormous costs and engineering trade-offs: the generator is in the nacelle up high, adding structural cost to the tower, which, at 150m+ nowadays, is a big deal; not to mention the rotors which span the area of a sports stadium. This doesn't scale, whereas kites do, because the tower/blade height/length cost is gone, the generator sits on the ground, and can be bigger (easy access, cheaper, heavier magnets, among other benefits).
Maintenance (and finance of turbine project bearing this in mind) is huge. Servicing an offshore turbine is weather limited and expensive even if you can get there. For kites, just reel them in by pulling more power off the generator to wind in the kites. If they are offshore, then sail the boat (?autonomously) back to a harbor. The list goes on and on, and amazing possibilities open up with a moment's thought.
Agreed with responder that it is early days for the technology, but I expect strong progress through up learning curve from this early stage. Good luck Makani!
Ground generation, where you let the kite unwind the tether and have generator connected to the spool. Occasionally you need to expend energy to wind it back up, but this can easily be made work out as a net positive.
Airborne generation, where you have small turbines with generators on the wing and lead the power down through the tether.
The kites are expected to be cheaper to maintain and install than traditional turbines, and can be mounted on old turbine bases.
If you think drones are loud, wait until you've heard an industrial kite/drone combo take off in an empty office space.
As to the tether, people are of course aware of the requirements it needs to fulfil, you can even find calculations about it online. Making it strong enough and still light is not a problem, the challenge is really in combining a structural tether with a conducting cable. It is a challenge, true, but it's far from impossible and there are several possible designs.
Makani's 600 kW prototype: https://www.youtube.com/watch?v=An8vtD1FDqs
We already have solar plants selling at around $30 per MWh, so that doesn't seem like it will be a major source, although it has the potential to run all day and all night, unlike solar.
I guess I don't know what the answer is. Pursuing new ideas is worthwhile, but I don't expect this company to have real commercial success.
This process is the answer ....
There's plenty of technologies that we are using today that previously failed. Like touch screens, now they are everywhere. And pretty much ever single technology had naysayers saying it wouldn't work for one reason or another.
And yeah most of the time the naysayers are right. Most attempts to innovate fail.
But maybe in 20 years these could completely replace traditional wind turbines and people will see them as the non-viable technology.
We don't know. Hence the need for research and development.
I'm not remotely disagreeing with the general need for research and development. But I am firmly of the opinion that it should be research and development, not something planned to go from concept to commercial with an aggressive timeline like this.
It's an interesting approach.
In the long run, it might be possible to achieve higher energy density with kites due to dynamic repositioning. The economics of increased complexity for higher density might work out, but I suspect that the density would need to be significantly higher while maintaining similar consistency of output. Feathering a fixed turbine offline in high wind and spinning it up again as conditions become favorable looks quicker than cabling in and cabling out kites in similar conditions.
https://lirias.kuleuven.be/bitstream/123456789/398835/2/12-8...
The tether is a surprisingly large component of the system's drag. With the two kite design, most of the tether is stationary.
Hadn't heard much about it since, but am reminded of the proposal every time someone comes up with a comparable design -- to generate electricity at high altitude, where where winds are consistent and strong, and property prices are low -- using some lighter than air or self-propelled vehicle.
I see the gyromill plan has since morphed into a company SkyWindPower[2] and appears to look more like a 4-prop drone now, coincidentally.
[1] https://www.newscientist.com/article/mg16722574-800-reach-fo...
This article by Moritz Diehl describes very well the expected power output for a crosswind device. https://pdfs.semanticscholar.org/f5da/681fe152e5a81264f8a919....
Also it's important to note that the potential power output for any of these systems are proportional to the cosine of the tether angle, meaning that most of the advantage airborne systems to traditional turbines won't be so much that they can reach higher winds, but just the smaller amount of material required.
I was not able to find the numbers, but they would be interesting. Why not share them?
If its not windy enough, you have to take them in. Too windy or rainy, then pull the kites back. Wing is ripped or bow is cracked from wind or sun damage, time to rebuild.