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
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
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.