However 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.
However, experts disagree about the mechanism and the scale of the effect.
Scientists have 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.
The suggestion is that with further development, the principle could be extended to become a renewable energy resource in humid parts of the world, such as the tropics. However, while the prospect of free electricity from the air is tantalising, the prospect of harnessing enough of it to be widely useful is still a matter of some debate.
The University of Southampton says that a similar effect has been known for some time; it points out that tribocharging – the generation of charge by rubbing wool over amber or water droplets over water droplets – is the origin of thunderstorms.
The bottom line – we are always keen to find alternative energy sources, and this appears to be one. However it is a long way from being a realistic option.
Looks fun though!