Glow with the flow

A new way to use flowing water to generate electricity may lead to gadget-size, hydroelectric batteries. So say engineers at the University of Alberta in Edmonton, who have powered a tiny lamp by driving water through channels only about twice the diameter of a red blood cell.

The new approach to electric power uses no moving parts, such as in turbines. Instead, the rush of water on a miniature scale drags positive ions downstream, creating a usable voltage difference. The prototypes built so far can power only tiny devices, such as the light-emitting diodes used as on-off indicators in electronic devices. Only about 1 percent of the mechanical energy supplied to move the water gets converted to electricity, says Alberta mechanical engineer Daniel Y. Kwok.

To make an array of water-carrying channels, Kwok and his colleagues use a commercially available ceramic filter about the size of a cookie and riddled with about a million holes. The team forces water through the holes with a syringe or pressure from a water column. The scientists tap the resulting current simply by placing electrodes in the water on either side of the filter.

Kwok and his colleagues describe their new power-generating method in the November Journal of Micromechanics and Microengineering.


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