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SEPTEMBER/OCTOBER 2019
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DISCOVER 45
existing materials. “If you
don’t need a new material,
why invent one?” muses
Ramakrishna Podila, a physi-
cist at Clemson University
in South Carolina. And that
solution could soon come to
a gadget near you.
In China, Wang’s startup
company, NairTENG, is
already selling triboelectric-
powered air filters, with plans
to release TENG-based shoes — with
ports to charge your devices — in the
next two years. Soon, it’ll be possible
to recharge your phone’s battery with a
gentle stroll. Triboelectric devices could
show up in the U.S. within five years,
Wang predicts.
Like many new technologies, however,
the success or failure of triboelectrics as
a major energy source depends on how
well its applications can scale up and
endure conditions messier than a pristine
lab. Wang’s plastic spheres would need
to be durable enough
to withstand the ele-
ments, and be specially
designed not to interfere
with marine life. Plus, it’s
not clear they could be
produced in the massive
numbers Wang’s dreams
require. Some research-
ers aren’t even convinced
there’s much of a future
for triboelectrics beyond
portable devices.
But perhaps the biggest open question
hanging over TENGs is why they work
at all. High school physics teachers and
college professors tell students that the
materials exchange charges, citing terms
like electron affinity. But in reality, says
Podila, scientists don’t really understand
why those charges move. Some physicists
think individual charged particles like
electrons jump from one material to
another; others argue that entire charged
molecules, called ions, do the jumping.
Still others suggest that tiny fragments
of one material break off on one another,
taking their charges with them.
“The fundamental science is largely
unknown,” says Podila. While not a
problem now, a failure to understand the
basics could hamper scientists’ efforts to
make more efficient energy harvesters
and contribute a solution to the world’s
energy crisis.
Wang agrees that understanding why
static electricity works is a critical step in
producing the technology, but he thinks
that’s a surmountable obstacle. He has no
doubts about its potential.
The world has spent nearly 200 years
developing electric tools that exploit
Faraday’s ideas about electromagne-
tism, turning motion into electricity.
For Wang, triboelectricity as an energy
source is a newborn: “This is just
the beginning.”
D
Stephen Ornes lives and writes in Nashville,
Tenn. Visit him online at stephenornes.com.
Perhaps the
biggest open
question hanging
over TENGs is why
they work at all.
Triboelectricity can power
many kinds of devices.
Clockwise from left:
A computer keyboard
generates voltage with
every keystroke; sliding
two materials together
lights up LEDs; generators
in shoes would produce
a current with every step;
and a high-tech cloth
bracelet gathers energy
from arm motions.