The Windbelt is a wind power harvesting device invented by Shawn Frayne 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
vortex shedding
In fluid dynamics, vortex shedding is an oscillating flow that takes place when a fluid such as air or water flows past a bluff (as opposed to streamlined) body at certain velocities, depending on the size and shape of the body. In this flow, v ...
, similar to the action of an
aeolian harp
An Aeolian harp (also wind harp) is a musical instrument that is played by the wind. Named for Aeolus, the ancient Greek god of the wind, the traditional Aeolian harp is essentially a wooden box including a sounding board, with strings stretched ...
. The vibrating movement of the magnets induces current in nearby
pickup coils by
electromagnetic induction
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk ...
.
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 microBelt, a 12 cm version. This could be put into production in around six months. Its expected to produce 1 milliwatt average. To charge a pair of ideal rechargeable AA cells (2.5Ah 1.2v) this would take 6000 hours, or 250 days.
* The Windcell, a 1-metre version that could be used to power meshed WiFi repeaters, charge cellphones, or run LED lights. This could go into production within 18 to 24 months. It is hoped that a square metre panel at 6 m/s average windspeed can generate 10 W average.
* An experimental 10-metre model that has no production date.
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.
[Reed Business Information. "Technology." Electronics Weekly 16 January 2008: n. pag. General OneFile. Web. 9 October 2009.]
The inventor's claims that the device is 10–30 times more efficient than
small wind turbine
Small wind turbines, also known as micro wind turbines, are used for microgeneration of electricity, as opposed to large commercial wind turbines, such as those found in wind farms. Small wind turbines often have passive yaw systems as opposed ...
s 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 (''ηC
p'') 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.
Footnotes
References
Instructions for building a proof-of-concept windbelt-powered lamp with parts recovered from an old hard driveREUK.co.uk 17 October 2007
Windbelt - reinventing wind powerphysics.org 22 April 2010
External links
{{Webarchive, url=https://web.archive.org/web/20071021214844/http://humdingerwind.com/windbelt.html , date=21 October 2007
Energy Harvesting Journal, 30 Mar 2010Wind energy harvester from Humdinger
Wind power
Electrical generators
Energy harvesting