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Flying kites deliver container-sized power generation

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Re: Flying kites deliver container-sized power generation

#161

Post by fransje26 »

xg15 wrote: post #129

It's an amazing project, but, out of curiosity: Why do all the AWE projects except Google's seem to use the reel-in/reel-out approach and don't attach turbines to the kite itself? Reel-in/reel-out seems a lot more complicated, power inefficient and taxing on the material than just having the kite up there (semi-) permanently. I assume there are some technical reasons why turbines are less practical, but could anyone…

There are plenty of reasons:

- costs 1): You would need a very different kite to have a turbine hanging in the air. Possibly rigid. They work with a flexible kite, that is possibly much closer to already existing high-performance kites/paragliding wings

- costs 2): You will need a much more expensive tether, as you now need to bring down the electricity that you've produced up in the air, while still being able to reliably and safely reel in your kite

- costs 3): Something happens in flight during testing, or maybe in production, and the kite comes crashing down. There goes your expensive turbine.

- power efficiency: Why would a turbine be necessarily be more power efficient? Action is reaction, so if you are going to remove a certain amount of energy from the air and your kite is stationary, you're going to have to produce a counter-force to stay in place. So how much of the potential energy are you actually using for power generation? Less than half, perhaps? So maybe the pump cycles of a dynamic kite are not that bad after all.

Just some thoughts.

Re: Flying kites deliver container-sized power generation

#162

Post by sjducb »

ClumsyPilot wrote: post #148
fwip wrote: post #132

Earlier quoted context omitted.

I only have wikipedia-level knowledge, but my understanding is that turbines are heavy, and wind power spent holding the turbines up is power that isn't converted to electricity. If you want to put the turbine up high, you can save power by just building a traditional fan-on-a-stick wind turbine.

This is wrong in physics terms. Lifting things requires power, there is a formula for work done. Keeping things up does not require power, a chair does not collapse under you when it runs out of battery. A ‘normal’ wind turbine generates a huge force on its foundations when it operates - that’s why they have to be so heavy. It’s not moving so no work is done. That force does not care what is opposing it - whether it…

> This is wrong in physics terms.

> Lifting things requires power, there is a formula for work done. Keeping things up does not require power

When my helicopter is hovering it runs out of fuel. What is my pilot is doing wrong?

Re: Flying kites deliver container-sized power generation

#163

Post by wongarsu »

tomatotomato37 wrote: post #123
jeffbee wrote: post #96

Earlier quoted context omitted.

And yet. https://www.google.com/maps/@43.0700265,-95.6508704,3a,60y,9...

That's a turbine in the middle of active farmfield, off a dirt road, servicing a town a bit under a mile away that is barely 10 city blocks wide at its widest point. In the middle of Iowa. My point just because you can build the turbines to clear everything, there are areas in this nation where there's just no point to doing that; and it's more economical to just make them shorter and put the money towards something…

You want your wind turbines as high as possible anyways. Higher up there are stronger and more consistent winds.

Re: Flying kites deliver container-sized power generation

#164

Post by wongarsu »

londons_explore wrote: post #92
kingkawn wrote: post #90

Earlier quoted context omitted.

Why not? Seems easy to teach the robots to not harvest on the road

Odd shapes and constantly starting/stopping the plougher/seeder/harvester mean you get less ROI on your equipment. Farming is super tight margins - if your machines waste 20% of the time starting and stopping every time they pass over a road, your farms profits are wiped out. This is true whether the machines are robot driven or not, and it's the reason most commercial farms have huuuuuge fields rather than lots of s…

I have trouble imagining that the cost of interrupting your seeder or lifting your plough every quarter mile is really higher than the profit generated by the wind turbines.

Re: Flying kites deliver container-sized power generation

#165

Post by JoeAltmaier »

pierrekin wrote: post #32
JoeAltmaier wrote: post #2

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.

> 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. Why is this nonsense on the face of it? This is just how kites work. Do you imagine that kite surfers just overpower the kite with their might and pull it back to the ground when they've had enough?

No. I said I didn't. I said I believed there was more to it.

Others have actually elaborated on the likely mechanism. But sure, mocking people is a kind of post I guess.

Re: Flying kites deliver container-sized power generation

#166

Post by helpfulContrib »

zardo wrote: post #59
pierrekin wrote: post #30

Earlier quoted context omitted.

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.

Yeah, that's sailboard territory, or a small dingy with no intention of going fast.

[dead]

Re: Flying kites deliver container-sized power generation

#167

Post by btbuildem »

londons_explore wrote: post #89
thechao wrote: post #73

Earlier quoted context omitted.

The back-of-the-envelope analysis for kite-based power is very compelling; enough that I tried my hand at designing a kite-powered system in ~2004. I don't think anyone can really appreciate how challenging the engineering (control systems) are for all-weather kite-flying until they just try to reel-in & reel-out a kite on a relatively calm day. I literally couldn't even write-down the differential equation which des…

Don't take the hard maths approach when you can take the lazy AI approach... Just fly a kite by hand, log the data, stick it through a reinforcement learning system to make you a controller that keeps the kite in the air. Reinforcement learning loves these kind of problems that only have double digit numbers of scalar inputs and outputs. Either way, my kite flying experience tells me that your reel-motors must move w…

I wonder if it would work better if there was a swarm of kites - or at least several deployed in the same area. Far enough from each other to avoid interference, but close enough so they could share data about the air movement.

I agree with the sentiment that going at it from first principles sounds like a nightmare; teaching-by-example AI approach seems like a faster path to success.

Re: Flying kites deliver container-sized power generation

#168

Post by Cthulhu_ »

NullPrefix wrote: post #58
nirolo wrote: post #48

There's been a recent video by the German "Sendung mit der Maus" (basically how does stuff work for little children) about these kind of generators. I did not double check if the company in the video is the German one mentioned in the article, but chances are high. Video and subs are in German only, but it's less than 10 minutes and one can see a little how it works. https://m.youtube.com/watch?v=aqfFZDWiJOI

Why are these people wearing safety helmets? Does this imply that everyone living under the kites will have to wear one too?

I doubt people will be living under the kites. I doubt there can be anything in the vicinity of the kite flying range for that matter, so no windmills or high tension lines or buildings or anything, which limits this thing's options especially in higher density countries like NL.

Re: Flying kites deliver container-sized power generation

#169

Post by perilunar »

OtherShrezzing wrote: post #114
xyzzy_plugh wrote: post #107

Earlier quoted context omitted.

Of course it doesn't. We don't build nuclear generators with pre-approved unusable exclusions zones. This is a ridiculous suggestion. Should we consider the potential blast radius of the catastrophic failure of wind turbines as well? You literally cannot build structures in the path of a wind turbine if you want it to function.

>Of course it doesn't. We don't build nuclear generators with pre-approved unusable exclusions zones. This is a ridiculous suggestion. I'm not suggesting we assign 5,000km^2 to each individual nuclear plant, just in case they explode. I'm suggesting the 5,000km^2 that currently exists as barren nuclear wasteland should be included in the total land attributed to nuclear energy. That would bring down the average gener…

> I'm suggesting the 5,000km^2 that currently exists as barren nuclear wasteland should be included in the total land attributed to nuclear energy

It's definitely not 'barren'. I'd suggest it should be counted as nature reserves. See:

"How Chernobyl has become an unexpected haven for wildlife" https://www.unep.org/news-and-stories/story/how-chernobyl-ha...

Re: Flying kites deliver container-sized power generation

#170

Post by psd1 »

zensavona wrote: post #77
Scea91 wrote: post #61

Interestingly, the very first statement is quite misleading. The statement: > On average, a humble wind turbine uses less land area per megawatt-hour than almost any other power source. The article itself refers to this citation [1]. It says, unsurprisingly, that the most land efficient power source is nuclear. The statement is of course technically true because it says "almost any power source". With wind, however,…

Sounds like the article used just the right wording then. “…less land area per megawatt-hour than almost any other power source.” As I read it this implies there is one (or some very small percentage) power source which uses less land per megawatt-hour, which is exactly the case.

Tidal energy.
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