Hydrogen
is the most abundant element on Earth. And it’s potential as a fuel could
revolutionize the energy market because using it doesn’t produce any emissions.
Zero. Unfortunately, it’s lightweight gas and rises into the atmosphere, which
means its rarely found in its pure form. And making making it produces
emissions.
Erik
Koepf, a mechanical engineering PhD student at the University of Delaware, may
have found a way to make hydrogen fuel cheaply, using only sunlight, zinc oxide
and water.
He built
a device that has a mirror and chamber, which holds the zinc oxide. The mirror
concentrates the sunlight into the chamber holding the zinc oxide. The
concentrated light is so intense, with temperatures hitting up to 3,500 degrees
Fahrenheit, that when it hits the zinc oxide the heat separates the zinc and
oxygen, and the zinc becomes a vapor.
In a
large facility, the zinc vapor would be added to water, which reacts with it
and turns into zinc oxide again, releasing the hydrogen. Koepf’s apparatus doesn’t
perform that second step, which is actually simpler.
It’s the
first step that’s more challenging, “because it requires very high
temperatures,” said Ajay Prasad, a professor of mechanical engineering at the
University of Delaware and Koepf’s PhD adviser.
Since the
product is zinc oxide, the same chemical the reaction started with, it can be
used over and over again. The only waste produced is oxygen. Since the power
source is sunlight, it eliminates the problem of the vast amounts of
electricity needed in other hydrogen-producing reactions, such as electrolyzing
water.
The
device is being tested at the Swiss Federal Institute of Technology, and there
are still questions about whether it can be scaled up. Thus far the amounts of
hydrogen and zinc produced have been small, and the reaction chamber Koepf
designed only takes care of the first step, making the zinc vapor. The next
stage will be setting up the water-zinc reaction to more efficiently produce
the hydrogen.
Koepf
will also be testing a reflector designed to concentrate the sunlight.
Initially he used an existing mirror at the Institute to concentrate the
sunlight, but to run this next set of tests he’ll be using a water-cooled
version of his own design to reach the temperatures necessary to drive the
reaction.
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