Friday, 27 August 2010

Scheme to 'pull electricity from the air'

Tiny charges gathered directly from humid air could be harnessed to generate electricity, researchers say.

Dr Francesco Galembeck told the American Chemical Society meeting in Boston that the technique exploited a little-known atmospheric effect.

Tests had shown that metals could be used to gather the charges, he said, opening up a potential energy source in humid climates.
"The work I'm presenting here shows that metals placed under a wet environment actually become charged."

Dr Galembeck and his colleagues isolated various metals and pairs of metals separated by a non-conducting separator - a capacitor, in effect - and allowed nitrogen gas with varying amounts of water vapour to pass over them.

What the team found was that charge built up on the metals - in varying amounts, and either positive or negative. Such charge could be connected to a circuit periodically to create useful electricity.

The effect is incredibly small - gathering an amount of charge 100 million times smaller over a given area than a solar cell produces - but seems to represent a means of charge accumulation that has been overlooked until now.

However, experts disagree about the mechanism and the scale of the effect.

"The basic idea is that when you have any solid or liquid in a humid environment, you have absorption of water at the surface," Dr Galembeck, from the University of Campinas in Brazil, told BBC News.
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