Logic of Giant Kites

[Roderick Read]

The logic of Giant Kites
Wind power is viable, only, without towers.

Wind carries hundreds of times the total human energy demand. To mine it, standard turbines would require impossible amounts of steel and concrete.
A new power race has begun.
Squadrons of kite machines prepare to battle for dominance in air power.

Kites to harvest the sustainable power we crave.
Kites have power. So much power, Americas Cup yachting banned them. Pulling one yacht is easy, but how can you pull enough power for cities and cars?
A wing

[Rob Beckers]

Roderick, welcome to the forum!

Actually, wind power with towers is quite viable: The very large utility scale wind turbines produce power at the same cost as a coal-fired power plant. We're talking about the big 4+ MW turbines that are placed in very windy locations.

What's less viable are the small "home" scale wind turbines, unless you happen to live in a very windy place, or have very high electricity prices.

I'm not convinced that trying to turn a kite into a wind turbine is going to work all that well. It's hard enough to make a reliable regular wind turbine; the small ones fail with alarming frequency. Just because there is more energy in the winds higher up doesn't mean we have to harvest them. As an analogy, solar radiation intensity is quite a bit higher out in space, but putting panels out there may just not be worth it.

-RoB-

[Roderick Read]

Thanks for your reply Rob.
The problem I was trying to outline and solve seems to have been a bit cut short in my first post..
sorry.
Try this full article https://medium.com/what-i-learned-building/bb928aca0ab6
That's where I stand

[Chris Olson]

Try this full article https://medium.com/what-i-learned-building/bb928aca0ab6
That's where I stand

I would say that article was written by a person that has very limited (as in probably none) experience with wind power. And it seems that wind power is the subject of many of these wild schemes that tend to pop up on the internet.

Take it from somebody that has experience with both wind power and sailing - a tower with a turbine on it is way simpler and more effective than that conglomeration of lines shown in that picture with the big sail. IMHO, anybody that thinks something like that is actually practical probably works for the US government (which means they're not very smart in the first place).
--
Chris

[Roderick Read]

Thanks Chris,
Suppose I better defend myself.
That concept sketch comes from aggregated research into how to make and control a huge sail, which is both safe and economically viable as a generation device.
Please don't consider Airborne Wind Energy as a passing internet fad. It's very real.
I'm new on this forum but this argument has raged for years on the yahoo airborne wind energy forum.
I got my electrical electronics engineering degree, worked in offshore comms, did plenty sailing, windsurfing, kitesurfing and was involved in making an axial flux turbine along Hugh Piggots designs. Love his books. Know my wind power arguments.
The animations I describe on youtube give a more comprehensive set of possible operational modes for arch kites. Very often a standard rigid wing user has issue that soft kite designs are not going for maximum tip speed ratio ... Please try to address the logic of the engineering arguments and don't worry about what a weirdo I may be.

[Chris Olson]

Like I said, it is obvious you have zero experience with wind power. Being involved in a Piggot build does not qualify.

After you get experience with wind power you will learn that, traditionally, the only advantage wind power has held over solar is in the amount of real estate it takes to generate a MWh of electricity. In recent years, with the wind power industry fighting a constant battle with the general public and zoning and permitting authorities on siting and setback requirements, wind power has lost that advantage.

My field is mechanical engineering, 19 years in the power generation business as a ME with Cummins. Assuming you could get such a contraption tacking the wind and pulling ropes to turn a generator (which you won't), getting it sited and permitted will be impossible.

From the engineering aspect, it requires 23,730 Nm of torque to turn the input shaft of a 1.5 MW 4-pole generator at full load and 75% mechanical and electrical efficiency combined. Calculating the tensile load on the wire ropes that are available today, turning a generator with a sail pulling ropes, puts this concept right up there with the (also far out) theory of putting vehicles into orbit by climbing a tether from the earth to a space station in orbit on the end of the tether. By comparison, you can generate that same amount of power with a Vestas V82 taking up only 0.6 hectares of real estate (less the setback requirements required by permitting and zoning).

Using the wind for power is almost as old as the wind itself. It has been used to pump water since at least the 9th century in what is today Afghanistan, Iran and Pakistan. But it is a secondary solar power source. Large scale commercial wind power will eventually die because it is too expensive/MWh and the uptime of large commercial wind generation has historically been less than dismal.

Go to the source of the wind itself - the sun. Sol powers everything on this planet, including the food you eat and the petrol that you pump into your car. You can turn sunlight into electricity with no moving parts. Wind power is only really viable as a supplement to solar, allowing you to capture solar power on days when the sun is hidden by local weather conditions. If you want to see the power contained in just a few square cm of solar radiation, with a small magnifying glass focus the sunlight into a point then measure the power output of that point of sunlight with a calorimeter. Then you'll be on to something.
--
Chris

[Roderick Read]

Assuming you could get such a contraption tacking the wind and pulling ropes to turn a generator (which you won't), getting it sited and permitted will be impossible.
An ME seriously? This all happens already thanks.
wire ropes Really? How long ago did we last use those?
Yeah and the sun also powers the tides.
But I'd have to assume you knew what seawater and gravity was first.
Are you really trying to argue the energy density and land economy of solar over wind?
Enjoy your last word turn now :sad::sick:
L8RS:idea:;)

[Chris Olson]

An ME seriously? This all happens already thanks.


Yes. This is the only privately owned Vestas V82 in the world:

http://youtu.be/PyehD1j0kUU

It was erected in three days, less site preparation and concrete work. It produces 1.65 MW @ 11 m/s and has provided 36% of the total power for the campus with an uptime of 91% since it was put up in 2006. And it does it in a relatively poor wind zone and siting.

Please provide me with a place and time where I can go and see a working kite turbine that is comparable to the V82 I pointed out above and has similar performance and uptime specifications. My wife and I will be in Sweden the week of Nov 10 and I would like to see the kite turbine at that time.
--
Chris

[Dale Sheler]

LOL, that kite scheme looks like something directly out of a Rube Goldberg cartoon.