Washington, June 14 (IANS) A phenomenon first observed by ancient Greek philosopher Theophrastus 2,300 years ago, has become the basis for a new device designed to harness enormous amounts of energy wasted as heat each year.
Zhong Lin Wang and colleagues at Georgia Tech, US, explain that more than 50 percent of the energy generated in the US alone each year is wasted as heat, released by everything from computers to cars to power transmission lines.
Heat can be converted into electricity using something called the pyroelectric effect, first described by Theophrastus in 314 B.C., when he noticed the gemstone tourmaline produced static electricity and attracted bits of straw when heated.
Heating and cooling rearrange the molecular structure of certain materials, including tourmaline, and create an imbalance of electrons that generates an electric current, the journal Nano Letters reports.
Wang's group wanted to apply the ancient principle to make a nanogenerator (NG) that could take advantage of heat changes in the modern world, which uses a time-dependent temperature change to generate electricity, according to a Georgia Tech statement.
Accordingly, the researchers made nanowires out of zinc oxide, a compound added to paints, plastics, electronics and even food. Using an array of short lengths of nanowire standing on end, they demonstrated a device that produces electricity when heated or cooled.
They suggest the nanogenerators could even produce power as temperatures fluctuate from day to night.
"This new type of NG can be the basis for self-powered nanotechnology that harnesses thermal energy for applications such as wireless sensors, temperature imaging, medical diagnostics and personal microelectronics," a researcher said.
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