Experiments with
Alternative Energy
Part 10 - Fuel Cell Basics
By John Gavlik, WA6ZOK
An exciting component in the field of alternative
energy is the fuel cell. If powered by hydrogen, its
fuel source can be extracted directly from water by
electrolyzing (splitting) it into hydrogen and oxygen.
Besides heat, the only byproduct a hydrogen fuel
cell produces is water; when the two gasses are
recombined internally, electricity is generated.
Thus, the hydrogen fuel cell can be pollution-free
and usually has more energy output as compared
with a battery of the same size and weight. As such,
fuel cells are beginning to draw the attention of
many commercial applications including auxiliary
power generators, powering your electric car, and
replacing your cell phone battery to mention a few.
Large stationary fuel cells already power homes
and commercial buildings, and more are being
added daily to supplement grid power (see the
Sidebar on Types of Fuel Cells).
Figure 1. PEM
Fuel Cell.
With all these advantages, why
aren’t fuel cells more popular and
widespread? There are two main
reasons: one is high cost and the
other is the lack of a safe, pollution-free fuel source in a form that is
suitable for direct energy conversion
to electricity. For example, a
hydrogen fuel cell uses platinum for
its MEA (Membrane Electrode
Assembly — see the Sidebar on
MEA) which is one of the most
expensive and rare metals on earth.
Plus, hydrogen is not naturally
available in free form since it is
chemically bonded to other elements
like oxygen in water and in natural
gas where a great deal of energy is
required to extract it in pure form.
There are other fuel cell types like
methanol, alkaline, and solid oxide,
and each have their own advantages
and drawbacks
including again cost, as well as
toxicity and safety issues. Things are
beginning to change, however, in
favor of fuel cell technologies to
make them more affordable with
greater fuel availability along with
safer operating and storage
conditions. With that in mind, let me
introduce you to this technology by
doing some interesting experiments
with one of them.
The PEM
“Reversible” Fuel Cell
There are many types of fuel
cells out there to choose from but
the one that can demonstrate most
of a fuel cell’s characteristics, as
well as be affordable, easy to use,
and safe is the PEM reversible fuel
cell. PEM can mean Proton
Exchange Membrane or Polymer
Electrolyte Membrane. Take your
pick — both refer to the part that
separates the hydrogen protons
and electrons to produce electricity
(Figure 1). The reversible part means
that it serves as both an electrolyzer
for water to create hydrogen and
oxygen, as well as a fuel cell. You
get the best of both worlds with this
device as it mimics a rechargeable
battery. The main difference is that
the electrolyte is external and does
not get used up in the process of
generating [DC] electricity. It can
continue to generate electricity as
long as hydrogen and oxygen are
available.
May 2010 47
