Wind energy extraction does not necessarily *have* to use a lot of materials..

[Fumesucker]

This post is prompted by the two recent locked threads here regarding wind energy extraction.

Towers with propellers on them require a large amount of materials for the towers and the blades, that is necessitated by two things, the need to raise the blades into the air and the low velocity of winds close to the ground.

Both of those constraints can be overcome by thinking about wind energy in a non traditional way.

It is possible to harness wind energy with flying devices such as kites or even autogyros..



http://en.wikipedia.org/wiki/Kitegen

http://www.windpowerengineering.com/news/wind-kite-concept-could-generate-plenty-of-power/



http://www.xercesblue.org/index_en.html

http://www.youtube.com/watch?v=3ccdtr1MuUk&feature=player_embedded



http://www.skywindpower.com/ww/index.htm

[ret5hd]

1. What happens when it gets caught in a tree?

[Fumesucker]

2. Charlie Brown won't be flying it..

A computer that is probably better than CB will be doing the controlling..

And not everywhere has trees.

I live in a heavily forested part of the nation and I've flown kites to near invisibility without having them caught in a tree.

[NickB79]

3. What happens when the wind dies down?

The flying turbine in the last picture you posted doesn't look like it could survive a fall from thousands of feet up without serious damage to itself.

[Fumesucker]

4. At those altitudes the wind doesn't die down that often..

When it does die down though you just use the generators as motors and fly the whole thing to the ground.

Taking off also is done by using the generators as motors, all under sophisticated computer control.

Keep in mind that the first civilian robotic plane to cross the Atlantic Ocean was in 1998, computers flying aircraft is old hat by now.

http://www.barnardmicrosystems.com/L4E_atlantic_crossing_I.htm



Most of the obvious questions are answered in the links I posted.

[NickB79]

5. Thank you for that reply

I didn't know the turbine blades could also be used as propeller blades; I thought there would be issues with the surface area and the way the blades are angled. Good to know!

[Fumesucker]

6. The rotor blades are very lightly loaded when used under power..

There's no fuel on board and no provision for passengers or load (other than the tether which holds the aircraft in place and carries electricity to/from it) so the blades don't have to be very efficient when used to fly up or down from normal station.

The energy inherent in wind power varies with the cube of wind velocity so by flying the actual wind catching device at altitude the efficiency gets much better for a given size of "blade" be it a kite or rotor blade or whatever since wind velocity is generally greater the higher the altitude.