ResoSOL: Réseau sol(ID)aire des énergies ! ENERGIES RENOUVELABLES
Scientists seek new energy solution in water

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     A team of scientists has discovered a completely new way to make electricity from flowing water.
    The breakthrough, the first new method of electricity production for 160 years, could provide free, clean energy for devices such as mobile phones and calculators.
    On a large scale, it could conceivably be used to feed power into the national grid.
    Dr David Lynch, Dean of the Faculty of Engineering at the University of Alberta in Canada, where the technology was developed, said: "The discovery of an entirely new way of producing power is an incredible fundamental research breakthrough that occurs once in a lifetime."
    A water powered mobile phone would contain a small reservoir pressurised by a hand pump.
    Electricity is generated as the water is released and surges through an array of tiny microchannels.
    The system relies on the natural 'electrokinetic' effect of a fluid flowing over a solid surface.
    An interplay of forces results in a thin layer of water - where it meets the surface - with a net electric charge.
    This region is known as the Electric Double Layer (EDL). Normally it goes unnoticed, but the Alberta scientists found that forcing water through a channel with a diameter similar to the EDL produces a flowing current.
    The amount of electricity generated by one microchannel is minute. But millions of parallel channels can produce enough power to operate electronic equipment such as a mobile phone.
Professor Larry Kostiuk, a thermodynamicist at the university, hit on the idea after a chance conversation with a fellow scientist about surface-interface phenomena.
    Later, he and nanofabrication researcher Professor Daniel Kwok - the other party in the conversation - illuminated a real light bulb by passing water through a porous glass filter.
    Their findings were published in the Journal of Micromechanics and Microengineering.
    Professor Kostiuk said: "This discovery has a huge number of possible applications. It could be a new alternative energy source to rival wind and solar power, although this would need huge bodies of water to work on a commercial scale."
    "Hydrocarbon fuels are still the best source of energy, but they're fast running out and so new options like this one could be vital in the future.
    "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."
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Scientists find new source of energy in tap water
BREAKTHROUGH: Researchers stumbled across a new method to generate electicity -- the first since 1839 --
which could lead to batteries that use ordinary tap water
Tuesday, Oct 21, 2003,Page 7
     Scientists who discovered a new way of generating electricity from water say they may have stumbled across an alternative source of clean energy to rival wind and solar power.
     The breakthrough, which scientists say is the first new way to generate electricity in 160 years, could lead to batteries that use water instead of toxic substances.
     The scientists made the discovery when they were investigating what happens when tap water is forced through extremely narrow glass tubes.
     Water squeezed down the tubes, each of which was narrower than a tenth the thickness of a human hair, generated a small electric current that ran the length of the tube. To produce larger electric currents, the team tried forcing water through a glass water filter that contained thousands of narrow channels lined up side by side.
     "When we took a syringe of water and squeezed it through the filter, we got enough power to light a light bulb," said Larry Kostiuk of the University of Alberta in Canada. "The harder you push the syringe, the more volts you get."
     The current is produced because of an effect in the glass tubes. When they are filled with water, positively charged ions embedded in the tubes are washed away, leaving a slight negative charge on the glass surface.
When water is then forced along the tube, the surface repels negatively charged ions in the water while positively charged ions are attracted down the tube. The result is a net flow of positively charged ions that sets up an electric current.
     According to Kostiuk, no one has ever thought to use water to produce electricity in this way.
     "The last time someone came up with a way of generating electricity was Michael Faraday in 1839," he said. "So this is the first new way of generating electricity in 160 years, which is why we are so excited about it."
     Kostiuk says water batteries might one day be used to power mobile phones and calculators, but conceded the engineering challenges might make other applications more realistic.
     "You'd need to be sure it wouldn't leak, and you'd need to make sure it wouldn't freeze," he said.
     More likely would be to install the electricity-generating devices where water is already being pumped, such as at city water filtration sites, he said.
     "It could ... rival wind and solar power," he added.
     The work is published in the Journal of Micromechanics and Microengineering yesterday.
     "It's the kind of system you might be able to use to scavenge power from the environment, where you already have rapid flows of water," said Andrew Holmes, an expert in microengineering at Imperial College, London.