The Windbelt is a wind power harvesting device invented by Shawn Frayn in 2004 for converting wind power to electricity. It consists of a flexible polymer ribbon stretched between supports transverse to the wind direction, with magnets glued to it. When the wind blows across it, the ribbon vibrates due to aeroelastic flutter, similar to the action of an aeolian harp. The vibrating movement of the magnets induces current in nearby pickup coils by electromagnetic induction.
One prototype has powered two LEDs, a radio, and a clock (separately) using wind generated from a household fan. The cost of the materials was well under US$10. $2–$5 for 40 mW is a cost of $50–$125 per watt.
There are three sizes in development:
The Windbelt's inventor, Shawn Frayn, was a winner of the 2007 Breakthrough Award from the publishers of the magazine, Popular Mechanics. He is trying to make the Windbelt cheaper.
The inventor's claims that the device is 10 - 30 times more efficient than small wind turbines have been refuted by tests. The microWindbelt could generate 0.2 mW at a wind speed of 3.5 m/s and 5 mW at 7.5 m/s, which represent efficiencies (ηCp) of 0.21% and 0.53% respectively. Wind turbines typically have efficiencies of 1% to 10%. Since the Windbelt a number of other "flutter" wind harvester devices have been designed, but like the Windbelt almost all have efficiencies below turbine machines.