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Flying kites deliver container-sized power generation

spectrum.ieee.org

21–30 of 175 posts

Re: Flying kites deliver container-sized power generation

#21
post #8

Not to be a HN naysayer, but wasn't this tried already with Makani Power?[1] They even made a documentary about it[2] Compared to traditional wind turbines, this solution trades an enormous amount of complexity, maintenance, etc for small reductions in material cost. We should be churning out traditional wind turbines for cheap instead. [1] https://x.company/projects/makani/ [2] https://www.youtube.com/watch?v=qd_hEj…

This is a very different approach. The google approach is making an airplane fly in circles generating continuous power, this slowly lets a kite out then reels it in generating pulsed power that would need a battery to smooth out. This approach can use pretty standard kite technology which is far cheaper than airplane technology.

The article indicates that it comes with an integrated battery.

Re: Flying kites deliver container-sized power generation

#23
post #8

Earlier quoted context omitted.

This is a very different approach. The google approach is making an airplane fly in circles generating continuous power, this slowly lets a kite out then reels it in generating pulsed power that would need a battery to smooth out. This approach can use pretty standard kite technology which is far cheaper than airplane technology.

Use multiple kites in a staggered pattern so one of them is always generating near peak power. That complexity of course offsets all of the gains, but that's fine because it illustrates why this is an idea that just won't fly.

Batteries are fine, the majority of the time it'll be in the pull stage as once depowered (the power is taken out of the kite by releasing the brake lines) you can bring the kite back down pretty quickly. Having two with the cycles staggered would reduce this but you need batteries anyway because you can't rely on demand being flat.

The algorithms to control the kite are pretty straightforward, the complexity to self launch would be a bit tough but it's easy enough for a human to do so there is no need to include that complexity for the use cases this is targeting. This wouldn't be a set and forget solution, not yet.

The kites will wear out relatively quickly but they're cheap to replace.

I consider myself a pretty skeptical / practical Engineer and I don't see any show stoppers, I think it'll fit the niche they're targeting quite nicely.

Re: Flying kites deliver container-sized power generation

#24

Gotta be more to it. They blithly say, reeling it in takes a fraction of the energy it generates when it pulls the line out. But that's nonsense on the face of it. I'm guessing, it changes it's wind profile, maybe going edge-on or closing up, to make it easy to pull down again. Gotta be something.

On its face it sounds silly, until you get experience with wind surfing. It's using the same concept. Figure 8s generate the pulling force. When you stop the figure 8s, and change the angle of the kite, you get minimal pulling force.

Re: Flying kites deliver container-sized power generation

#25

How is the kite raised initially and what happens when air stops, how is it re-raised? Reading the article seems like it's pulled back if air is stopping, and slowly released based on air speed perhaps.

On islands where this is targeted the winds are usually very predictable, especially at higher altitudes. This isn't like flying a kite at ground level, there is no need to wench the kite back down to ground level, just up and down where the faster high altitude winds are.

Re: Flying kites deliver container-sized power generation

#26

How is the kite raised initially and what happens when air stops, how is it re-raised? Reading the article seems like it's pulled back if air is stopping, and slowly released based on air speed perhaps.

All of the raising is done by the wind.

Re: Flying kites deliver container-sized power generation

#27

Earlier quoted context omitted.

Use multiple kites in a staggered pattern so one of them is always generating near peak power. That complexity of course offsets all of the gains, but that's fine because it illustrates why this is an idea that just won't fly.

Batteries are fine, the majority of the time it'll be in the pull stage as once depowered (the power is taken out of the kite by releasing the brake lines) you can bring the kite back down pretty quickly. Having two with the cycles staggered would reduce this but you need batteries anyway because you can't rely on demand being flat. The algorithms to control the kite are pretty straightforward, the complexity to self…

From both a maintenance, operational cost and engineering complexity point of view I don't see this as viable, but I'm more than happy to be proven wrong by a party that brings it successfully to market. Meanwhile, any place where this kite system would work is one where a regular HAT would work as well and long term (25 year lifespan) total cost of ownership and $/KWh generated will be pretty easy to determine by deploying two systems side-by-side.

Re: Flying kites deliver container-sized power generation

#28

60 square meters of kite surface area is a lot of pull. 5 square meters can be enough to pick up 100kg in the right wind conditions.

Based on the numbers from the article: 40 kW * 80 s / 500 m is 650 kgf.

So maybe it will work. Still I feel like as soon as you get a moment of calm it will all break. The wind may be very reliable in places but is it ever so reliable that you don't get moments of calm for hours at a time?

Re: Flying kites deliver container-sized power generation

#29

60 square meters of kite surface area is a lot of pull. 5 square meters can be enough to pick up 100kg in the right wind conditions.

Based on the numbers from the article: 40 kW * 80 s / 500 m is 650 kgf. So maybe it will work. Still I feel like as soon as you get a moment of calm it will all break. The wind may be very reliable in places but is it ever so reliable that you don't get moments of calm for hours at a time?

When there is a break in the wind, you reel the kite in, creating apparent wind.

Re: Flying kites deliver container-sized power generation

#30

60 square meters of kite surface area is a lot of pull. 5 square meters can be enough to pick up 100kg in the right wind conditions.

A sailboat typically flies about 5 - 8 square meters of material in the sails, pulling 3 - 4 tons of material around the world ..

This doesn't seem right to me, in my experience a 3 - 4 ton sailboat is around 9m long, which has a sail in the 20 - 40 m^2 range.

A 5 - 8 square meter sail is really teenie tiny.

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