Let's go fly a k...

[polygonum]

I am trying to imagine the kiteage required to replace one modest power station (gas, oil, coal, nuclear or even recycled bog paper).

[Onetap]

Less daft than it first appears. There was a video of one on Youtube, simil ar appearance to an aircraft with propellors. The kite/aircraft did vigouro us aerobatics at the end of the tether and so the energy generated was not limited by the wind speed blowing through the turbine disc. Also eliminated the tower in favour of one tether wire.

Videos on that TEd thing, I think.

[Jethro_uk]

Didn't one of James May's progs cover this ... a dutch guy IIRC ?

[The Natural Philosopher]

Ahh. another perpetual motion machine then.

[The Natural Philosopher]

the energy extractable from wind is a function of the wind speed and the area over which it is collected.

You cant breach the laws of physics.

a 2MW turbine sweeps an area of a 100 meter diameter circle give or take. Go figure. it needs about a 35mph wind to reach full power.

I am amused to see 'guardian' and 'science' in the same URL.

Essentially its more eco-bollocks.

[Andy Burns]

Google have recently bought a kite-power company.

[The Natural Philosopher]

my wife recently bought some lipstick.

[dennis]

Not the same then.

The one in the article uses wind pressure on the sail to pull a cable and spin a generator. It then dumps the wind and rewinds the sail. Repeat.

A bit intermittent if you only have one.

If you have lots they save energy by grounding aircraft.

[Onetap]

Ye cannae break the laws of physics, Jim, surely?

This one;

It's not breaking the laws of physics, more bending the technology to fit the laws of physics.

So, a 2 kW turbine might sweep a 10m diameter circle and make 2 kW at 35 mph, lets say.

And two 10m diameter turbines mounted on a winged kite-type thing that could execute loops at 60 mph in a 35 mph wind will generate somewhat more than 4kW, I'd hope.

Reducing the turbine diameters, use cheaper fixed wings to get more kW per m diameter, eliminate the tower structure.

Nah, it's technology that has some good ideas in it and possibly might be made to work if a mound of cash is invested into it. Less eco-bollocks than offshore wind turbines.

But no-one has marketed it yet, so I'd think the problems have outlasted the cash, as they do.

[Onetap]

So they have, this one;

That's the company who made the Youtube video I mentioned, see link above.

Google's money may make it workable.

[The Natural Philosopher]

One might, but two together could not.All you are doing by letting the kite move, is increasing the swept area. In te limit, there is only so much swept area you can collect from.

Its a typical sleight of mind trick. Make one small kite generate a lot of apparent power, and then perform the sleight of mind, multiply them all up. Andignore the fact that you cant multiply them all up.

[Onetap]

It's just tecnology under development, to produce more kW/£ in both capit al and maintenance costs.

It can get to higher, faster winds.

There's pros and cons to all such schemes, whether they can make a marketab le product, that makes money without green tax injections, remains to be se en.

The wind sail thing seems to require repeated deployment and collapsing of the canopy. Parachutists have cut-away devices (Capewell releases or three-ring-circus things) to cut away the square canopy when it does fail to deploy and leave themselves enough altitude to deploy a reserve. Not very easy in the middle of the North Sea. Do they just cut away the sai l and abandon it, or hope it will always work?

[Nick]

I'm not following you. I don't think anyone is trying to break the first law of thermodynamics. The economic/efficiency/practicality optimization between size of kite and size/number of turbines doesn't seem at all obvious to me.

I can't see that Onetap was limiting the size of kite so the one small kite comment seems a little unfair. I certainly wouldn't describe a kite with 2 10m turbines attached as small.

[Tim Streater]

Where was onetap proposing to fly his kites, and at what altitude?

[The Natural Philosopher]

That is your problem...

its all relative.

[Onetap]

Up through the atmosphere, where the air is clear.

and

up to the highest heights.

[charles]

yes, Mr Poppins

[Tim Streater]

That's as opposed to down through the ground or water, then. Glad we got that cleared up.

[Onetap]

My pleasure, don't mention it. We have to set out thes design fundamental principles at the start.