New technology can harness temperature fluctuations of many kinds to produce electricity

By Warren Miller,
contributing writer

Finding new sources of sustainable energy is the next
frontier in the battle to decrease our reliance on fossil fuels. Solar panels
and wind farms have grown in popularity in recent years, but there may be an
even simpler way to collect energy from almost anywhere at any time. A research
team at MIT has developed the first thermal resonator,
a device that generates electricity from the small changes in the ambient
temperature around it.

In order to harvest the power from temperature fluctuation,
the scientists at MIT needed something both thermally conducive and possessing
a high thermal capacity; in other words, something made from materials that
both conduct heat and can store up a lot of it. They created a kind of metallic
foam consisting of copper or nickel that is subsequently coated with a thin
layer of graphene to improve thermal conduction. A waxy substance called
octadecane is then added to the mix – a phase-change material, octadecane
shifts between liquid and solid phases according to temperature. “The
phase-change material stores the heat,” said Anton Cottrill, one of nine
credited authors of a paper published in the journal Nature Communications. “And
the graphene gives you very fast conduction.”  

Thermal_Resonator

New technology can
harness temperature fluctuations of many kinds to produce electricity.
Image source: MIT.

To date, the device has only produced fairly inconsequential
amounts of electricity, but the technology does have some advantages over its
competitors. It doesn’t require sunlight or a stiff breeze to create power,
meaning it can even function while sitting at the bottom of your closet. The
researchers tested the device over a period of a single day in an open-air
environment, but the device could theoretically produce more power if subjected
to more extreme temperature changes (like the middle of the Mojave Desert, for
instance). In testing, a beta device generated 1.3 milliwatts of power from a
temperature disparity of only 10 degrees Celsius. While that’s only enough
energy to power a very small electronic device (such as a thermometer), it’s
still impressive after you consider it was essentially pulled right out from
the air around us.

While still in the very early stages, this technology has
huge potential for future applications. The drawbacks of other forms of clean,
sustainable energy are obvious. All the thermal resonator needs is an
environment in which the temperature isn’t being regulated, which basically
means outside, anywhere. While other technologies have succeeded in harnessing
energy from temperature fluctuation before, the thermal resonator created
approximately three times the power as those materials per amount of surface
area. If this kind of device can be replicated on a larger scale, it could help
to provide energy to those areas of the world that don’t get enough sun or
enjoy enough wind to make solar and wind energy practical energy solutions. After
all, air — and
therefore, air temperature — is almost everywhere, and what goes up, must come down (or vice
versa).