DAWN TO DUSK NEWS: Tribo-electric

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<span id="ctl00_ContentPlaceHolder1_lblNewsDetailMain"><b>PARIS: Out 
at sea, gentle waves provide power for thousands of homes. In cities, 
dancefloor moves generate electricity for nightclubs. In the 
countryside, hikers use leg power to recharge their phones.</b><br />
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It
 is an alluring goal of clean, reliable power free from geo-political 
risks -- and scientists in the United States said Tuesday it lies within
 reach, thanks to a smart way to harvest energy called 
tribo-electricity.<br />
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Researchers at the Georgia Institute of
 Technology said they had built a simple prototype device that converts 
stop-start movement into power.<br />
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Waves, walking and dancing
 -- even rainfall, computer keys or urban traffic -- could one day be 
harnessed to drive sensors, mobile gadgets or even electricity plants, 
they contend.<br />
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Zhong Lin Wang, a professor of materials science and engineering, described the invention a "breakthrough."<br />
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"Our
 technology can be used for large-scale energy harvesting, so that the 
energy we have wasted for centuries will be useful," he told AFP by 
email.<br />
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"Tribo-electric" is a modern term with ancient roots -- from the Greek word for "rub."<br />
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Its
 electricity is created from friction between two substances causing a 
charge of electrons to be transferred from one to the other.<br />
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It
 commonly happens, for instance, when plastic-soled shoes are in contact
 with a nylon carpet, causing the snap of static discharge when one's 
hand touches a metal doorknob.<br />
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Because tribo-electric is so unpredictable, it has been generally shunned as a power source.<br />
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The preferred method has been magnetic induction -- a turbine driven by nuclear- or fossil-powered steam or water.<br />
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But,
 in a new study published in the journal Nature Communications, Wang's 
team said they had overcome key hurdles to converting a 
haphazardly-generated electrical charge into current.<br />
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Their
 prototype comprises a disc about 10 centimetres (four inches) across, 
designed to show the potential from a small, portable generator moved by
 ambient energy.<br />
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Inside are two circular sheets of 
material, one an electron "donor" and the other an electron "receiver," 
brought together through rotary movement.<br />
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If the sheets are separated, one then holds an electrical charge isolated by the gap between them.<br />
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Sandwiched between the two discs is a third disc with electrodes, which bridges the gap and helps a small current to flow.<br />
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At a top speed of 3,000 revolutions per minute, the device generated 1.5 watts.<br />
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This
 gave it an energy efficiency of 24 percent, three times greater than 
piezoelectric, the previously best source of mechanical electricity 
harvesting -- and as efficient as magnetic-induction turbines.<br />
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It
 can run on a gentle wind or tap water, or "random jerky motions," 
including human movement, to provide the rotation, Wang said.<br />
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"As long as there is mechanical action, there is power that can be generated."<br />
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The
 prototype used copper for the rotator and gold for the electrodes in 
lab tests, but these could easily be substituted for low-cost 
synthetics, he said.<br />
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The team is working on ways to scale up tribo-electric energy for harvesting power from the ocean. (AFP)</span>
   
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Tribo-electric,' the buzzword of the future?

PARIS: Out at sea, gentle waves provide power for thousands of homes. In cities, dancefloor moves generate elec...