Tuesday, October 21, 2003

Discovery of new way to generate electricity means batteries could be powered by water

The battery of the future could be powered by nothing but water following the discovery of the first entirely new way to generate electricity in more than 160 years.

Though hydro-electric uses water to drive turbines to generate electricity, the technique found by two Canadian scientists is the first to convert water directly into electricity. The last new forms of electricity discovered was solar power and proton exchange membranes in 1839.

Initial applications could be mobile phones and other electronic devices that use rechargeable batteries, but Larry Kostiuk and Daniel Kwok, researchers at the University of Alberta who made the discovery, think that, in time, it could even be used for full-scale power generation. The "water battery" would be non-polluting, non-toxic and completely portable. And it could be ready for commercial application before the end of the decade. The discovery uses the movement of water through microscopic channels to generate electricity by using just a hand-operated syringe, some water and a piece of glass 1cm in diameter and 3mm long. It is a breakthrough application of nanotechnology, the science of molecule-sized artefacts.

And it was also a complete accident, caused by Dr Kostiuk's decision, after he was appointed head of the university's department of engineering, to discover what his colleagues were doing. One of those was Dr Kwok.

"How long did we work on it? Oh boy, it's embarrassing," said Dr Kostiuk, who normally works in the field of combustion chemistry. "It's not like we laboured for years. One afternoon I went to visit Daniel, and he was explaining what he did in electrokinetics [the science of electrical charge in moving substances such as water]."

Dr Kwok explained how, when water travels over a surface, the ions that it is made up of "rub" against the solid. That leaves the surface slightly charged. With water being made up of positive and negative elements, those with the same charge as the surface are slightly repelled; those with the opposite charge are attracted. That creates a thin liquid layer which has a net charge, known as the electric double layer. "So I said, 'If you separate the charges, then it looks a lot to me like a battery,'" recalled Dr Kostiuk. At which Dr Kwok abruptly started looking at his work with fresh eyes. "It derailed my whole afternoon," said Dr Kostiuk. "We spent hours talking about how you would generate electricity from it."

The work is published today by the Institute of Physics journal, Journal of Micromechanics and Microengineering.

And might it one day power everything? "You'd need a really big area, like a coastal region," said Dr Kostiuk. "But then again, I guess, those are available, aren't they?" For a clean, free form of electricity, the answer must surely be yes.


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