Mini Wind Turbines Could Power Wireless Devices
From the Nature.com article: "Wireless networks have freed us from miles of cumbersome wiring needed to carry information, but the electronic 'nodes' of such networks still need power. If geologists want to place hundreds of sensors on a mountain to monitor seismic activity, for example, they either have to supply electricity using cables or hike out to each sensor every six months or so to replace batteries." The windmill developed by Shashank Priya, an electrical engineer from the University of Texas, can get power from the most gentle breeze. It is about 10 centimeters (a bit less than 4 inches) across and it is attached to a rotating cam that flexes a series of piezoelectric crystals that generate a current as the blades rotates.
Priya has found that a gentle breeze of 16 kilometres per hour can generate a constant power of 7.5 milliwatts, which is more than enough to keep an electronic sensor running. [...]
The first trials of completely wireless sensor networks used photovoltaic cells for power. But these did not always work, since a spate of cloudy days could cause a node to shut down. "The idea failed because light isn't available everywhere and all the time," says Priya. [...]
We don't think that the point is to argue that these mini wind turbines are better than solar panels, but that in some cases they might be more appropriate or cost-effective.
The piezoelectric generator is much more efficient way of converting wind energy on a small scale than the conventional generators that create energy for the national power grid from wind turbines.
A conventional generator that used a 10-centimetre turbine would convert only 1% of the available wind energy directly into electricity. A piezoelectric generator ups that to 18%, which is comparable to the average efficiency of the best large-scale windmills, says Priya.
::Mini windmills power wireless networks, via ::Digg