A new way to generate electricity from water which could be used to power small electronic devices in the future has been developed by Canadian scientists.
It could provide new power for chips
The researchers have harnessed what happens to water when it is pumped through tiny channels.
"What we have achieved so far is to show that electrical power can be directly generated from flowing liquids in microchannels," said Professor Larry Kostiuk from University of Alberta.
The team says its "electrokinetic" battery could be further developed to provide a clean, non-polluting power source that could eventually drive small devices such as mobile phones.
But some experts in the field have cast doubt over its potential as a useful source of power.
Early promise
The research by Professor Kostiuk and colleague Professor Daniel Kwok is published by an Institute of Physics journal.
It is said to be the first new method of generating electricity in over 150 years.
The work is all to do with charge separation, and what happens to ions in liquids when they come into contact with a non-conducting solid.
Its best first application might be in the field of micro-electronic mechanic systems, like labs which are being built on computer chips which require power
Professor Kostiuk, University of Alberta
The team created a glass block, two centimetres in diameter and three millimetres thick, containing about 400,000 to 500,000 individual channels.
Thanks to a phenomenon called the electric double layer, when water flows through these 10-micron-diameter-wide channels, a positive charge is created at one end of the block and a negative charge at the other - just like a conventional battery.
The prototype generated about 10 volts with a current of around a milliamp. This allowed the team to successfully power a lightbulb.
The scientists stress their work is in its early stages.
Nano application
"The applications in electronics and microelectronic devices are very exciting," said Professor Kostiuk.
"This technology could provide a new power source for devices such as mobile phones or calculators which could be charged up by pumping water to high pressure."
They suggest more research needs to be done to develop the potential of how their prototype device can be turned into a battery for commercial use.
One mechanical engineering expert BBC News Online spoke to was hesitant about the potential uses of this energy source, however.
Dr Jon Gibbins from Imperial College London said he could only see it generating a small amount of power on a small scale, so it might have uses on a nanotech scale.
"Its best first application might be in the field of micro-electronic mechanic systems, like labs which are being built on computer chips which require power," said Professor Kostiuk, but the research is still in its infancy.
Improving efficiency
Making electricity from water is by no means new.
Large-scale power generation already happens with hydroelectric power turbines which are almost 100% efficient at converting available energy in the water to electricity.
Magnetohydrodynamic methods also generate electricity through water.
What Professor Kostiuk and his team have achieved is create a kind of turbine device that does not have moving parts.
"Efficiency is a fraction of 1% and right now we are trying to fully understand the characteristics of such devices.
"The real goal is to find ways of improving its efficiency to around four to 16% to compete with other energy sources."
When water is forced through thousands of tiny microchannels in a negatively-charged glass filter, a positive layer is created at one end, and a negative one at the other - exactly as in a conventional battery
This phenomenon is called an electrical double layer
When electrodes are attached at either end, an electric charge can be tapped. The prototype battery generated about 10 volts
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