Monday, December 20, 2004

Wind Power "Laddermills": High Altitude Kites to Replace Turbines?

High-altitude kites could be used to generate clean energy at a cost comparable with that of fossil fuel generation , researchers claim.

The "Laddermill" is a chain of controllable wing-like kites attached to a looped cable stretching more than five miles into the sky.

Strong high altitude winds acting on the "kitewings" produce as upward force on one side of the loop and a downward force on the other, causing it to rotate.

The slowly turning cable drives a power generator in the Laddermill base station.

Although the concept sounds far fetched, its developers at Delft Technical University in the Netherlands hope to build a working model in the next four years.

They claim one Laddermill could generate 100 megawatts of electricity, compared with only a few megawatts from a conventional wind turbine.

Winds at 30,000ft are 20 times more powerful than at sea level.

Professor Ockels, an ex-astronaut and head of the European Space Agency's education office, told The Engineer magazine: "Above a certain altitude there is a massive amount of wind power.

"Kites that can tap into that wind can generate a great deal of energy."

Full Size Visualisation of Wind Energy Laddermill

Graph Comparing Wind Power Generation of a wind turbine vs. a laddermill based on height and windspeed


Blogger Danothebaldyheid said...

Fascinating idea! I wonder about the possible effects on the environment though ( see for details)

5:15 a.m., December 21, 2004  
Blogger Engineer-Poet said...

I seem to recall reading about something like this many, many years ago in one of the Popular-something magazines.  Everything old is new again?

This may have some advantages over the other flying-wind-generator concept, the gyromill; the cables would have support from all altitudes at which there was wind, while the gyromill can only hold it up from the top.  On the down side, I'm sure that the support cables cannot transmit as much power mechanically as a wire could electrically.

5:10 p.m., December 22, 2004  
Blogger Stewart C. Russell said...

I'm sorry, but this is just plain dumb. We're already generating electricity from conventional wind turbines at a price comparable to that of "conventional" sources.

If you took a 100MW wind farm -- which today would be comprised of 1.5MW wind turbines, approximately 80m in diameter on 80m tower -- and stacked them on top of one another, they'd still be shorter than this cockamamie contraption.

What stops the strings crossing? What would you do in a lull -- would you be happy to have a highway five miles down the road blocked by a resting laddermill? How do you maintain the thing?

7:34 a.m., January 11, 2005  
Blogger Ben Gatti said...

The challenge with this technology is the incredible strength requirement of the Cables. - and the risk. Perhaps if Congress will give the good Dr. a free ride on liabiity insurance (Like they do the Nuclear Industry) these high risk ventures may be possible. But when you consider how much land is effectively "used" by virtue of the drop zone, it is largely an ineffecient use of resources.

8:10 a.m., May 11, 2005  
Anonymous Anonymous said...

American Windfarms is working with members of Engineers Without Borders ( across the land, to develop students' projects related to new energy.

We see the "laddermill" concept as a means to raise small generators into the jet stream, by attaching kiteplanes to a power cable, with the generators mounted on the kiteplanes. The students will build the kites, with the best principles of aerospace engineering, while sponsoring communities provide the materials.

We want to test N. Tesla's idea, about raising a series of antennaes into the plasma field around us, and provide cheap energy to any region that is willing to build their own energy system at low costs, through open-source collaboration.

We have posted a video of the laddermill on

Search on "laddermill"

4:52 p.m., January 05, 2007  

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