Laddermill, Delft University of Technology, Delft, the Netherlands
Researchers at Delft University are building what they call a Laddermill to tap the steady and stiff winds in the jet stream. The Laddermill consists of a stack of tethered kites that soar as high as five miles and then return toward earth in an endless loop to generate electricity.
Technology: As the kites sail up to the jet stream and back, they pull with them tethers that turn an electrical generator located on the ground. The Delft researchers also are experimenting with a fleet of gliders that would soar in place of the kites.
Energy production/savings: A Laddermill operating at 30,000 feet would generate an estimated 100 megawatts of electricity - enough to power 100,000 homes, according to Delft.
Stage of development: The project is still in the R&D phase, although Delft has proved the concept by generating ten kilowatts of electricity by flying a 107-square-foot kite.
Reality check: Commercial Laddermills are years away from operation and would have to operate in no-fly zones.
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