S N A P C H A T
A new battery cell design could
help us tap into the vast stores of
geothermal energy beneath our
feet. Tokyo Institute of Technology
and Sanoh Industrial have developed a new
type of battery cell that can directly convert heat
energy into electricity.
Unlike traditional geothermal systems that often
require high temperatures over 180° C and
are often hard to scale, the new system has a
more direct method. Their design is made up of
sensitised thermal cells (STCs), which are able to
generate electricity at temperatures below 100° C
(212° F) without needing a middle-ground carrier
like water or steam.
The STC is a battery made up of three layers of
material sandwiched between two electrodes.
There's an electron transport layer (ETM), a
semiconducting layer of germanium, and a solid
electrolyte layer that transports copper ions. This
battery is designed to be buried in the hot ground.
The idea is that the heat in the ground excites
the electrons in the semiconductor, causing them
to transfer to the ETM. That in turn passes them
via the electrode through an external circuit and
eventually back to the other electrode and into the
electrolyte. There, oxidation and reduction (redox)
reactions take place, which carries low-energy
electrons back into the semiconductor, starting the
cycle over again.