Tuesday 16 September, 2014

Ancient principle inspires new device to produce electricity from waste heat

Published On: Thu, Jun 14th, 2012 | Nanotechnology | By BioNews

Inspired by the observation of an ancient Greek philosopher, scientists have come up with a new device designed to harvest the enormous amounts of energy wasted as heat each year to produce electricity.

Zhong Lin Wang and colleagues at Georgia Tech explained that more than 50 percent of the energy generated in the U.S. each year goes to waste, much of it as heat released to the environment by everything from computers to cars to long-distance electric transmission lines.

Heat can be converted to electricity using something called the pyroelectric effect, first described by the Greek philosopher Theophrastus in 314 B.C., when he noticed the gemstone tourmaline produced static electricity and attracted bits of straw on being heated.

The first-of-its-kind “pyroelectric nanogenerator” is based on the principle that heating and cooling rearrange the molecular structure of certain materials, including tourmaline, and create an imbalance of electrons that generates an electric current.

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.

To do that, 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 harvests thermal energy from the time-dependent temperature fluctuation in our environment for applications such as wireless sensors, temperature imaging, medical diagnostics and personal microelectronics,” the authors said.

The report is published in ACS’ journal Nano Letters.

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