A fuel cell operates in much the same way as a storage battery, except that
the reactants are continuously being replenished. At one electrode hydrogen
is ionized and released into the electrolyte (the hydrogen can come from
either pure gaseous hydrogen or from a hydrogen rich fuel like natural gas),
the hydrogen ions combine with oxygen ions at the other electrode to form
water. The oxygen usually comes from ambient air.
When you do the chemistry, you see that electrons have to get transferred in
the process.
If you use pure hydrogen as the fuel, the cell should last pretty much
indefinitely. If you use natural gas or other hydrocarbon based fuel, my
guess is that the electrodes will become contaminated eventually and the
cell will stop working.
Fuel cells had been used for a long time in the space program, but were too
costly to be used in most other applications. Recent developments in
electrode technology have made them quite competitive for a number of
applications. For example, they are now often used in place of diesel
generators for backup power in critical applications. They are more
reliable and less polluting than diesel or gasoline generators.
They also are becoming practical for transportation applications.
Mark
-----Original Message-----
From: Jim Green
To: PHYS-L@lists.nau.edu
Sent: 6/2/2001 9:31 AM
Subject: Fuel Cells
Can someone please tutor me re "fuel cells" --
How do they work?
Tell me in what way the process is "renewable" -- Doesn't the energy of
the so called fuel have to be increased in some way -- ie doesn't the
likes
of H2 and O2 have to be made so that later they can react? IE the net
supply of electrical power is <0.
BTW I remember the early days of solar cells -- It required far more
fuel/electrical power to process the s/c than ever could be replaced in
the
lifetime of the cell. That is why our group stopped working on them.
IE
the net supply of electrical power was <0.
What is that status of this issue today?