September 1964 Popular Electronics
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When you think of typical primary battery cells (non-rechargeable
by definition), something like the standard Ray-O-Vac carbon
(actually zinc-carbon) model probably comes to mind. The reason
primary cells cannot be recharged is that the cathodes are consumed
in the reaction with the electrolyte during current flow. Secondary
cells are rechargeable because the current-producing reaction
does not consume the cathode (at least not as rapidly), so applying
a reverse voltage drives the electrons back from whence they
came allowing the discharge process to happen again. There is
another type of primary cell - the fuel cell - that never really
discharges but is constantly fed with a chemical (or combination
of chemicals) that facilitates a reaction between electrodes
and the electrolyte. Therefore it never needs to be recharged
in the traditional sense - just refueled. In a sense a fuel
cell is more of an electric generator than a battery. Turn off
the external energy source (coal, hydro, nuclear, wind, sunlight)
to a generator and the current flow stops. This report from
a 1964 edition of Popular Electronics describes some
of the early work on fuel cells.
The Fabulous Fuel Cell
By Walter G. Salm
Even as you read this, the first fuel cells are on their
way into space. Tomorrow? Fuel cell-powered cars are just one
One day in the not-too-distant future you may be able to
drive into a gas station, pull alongside a pump labeled "methane,"
and order a tankful for your car.
You won't be driving some new breed of jet or turbo-powered
chariot, but a car with a power plant that is as old as the
automotive industry itself - an electric motor. The unusual
feature of this car will be the part that provides the electricity,
a new kind of generating device that gulps a variety of inexpensive
gases and produces power. The device is called a fuel cell,
and while it is still experimental, companies working on its
development have already reported progress that seems almost
This generalized drawing shows basics of fuel cell operation.
The electrolyte may be liquid, semiliquid, or solid; the electrodes
can be carbon, plastic, platinum or nickel boride, typically
in combination. Fuel depends largely on the type of electrode
used; hydrogen reacts very easily, but inexpensive hydrocarbons
are now being used thanks to improvements in cell electrodes.
New electrode materials are constantly being
evaluated in the search for reliable, economical fuel cells.
At left, a G.E. researcher tests electrode material with electrolytes
of varying acidity and alkalinity.
The fuel cell is a kissing cousin of the more conventional
electrochemical batteries that we use every day. Like batteries,
it works through a chemical reaction that produces a lot of
free electrons. But unlike batteries, it can be "refueled" by
replacing chemicals that have been consumed in the reaction,
and it will continue to function at normal operating levels
all the while. And what operating levels they are! Fuel cell
modules have already been constructed with continuous outputs
of 2.5 kilowatts. When discussing characteristics and life tests,
it is customary to refer to a cell in terms of amperes-per-square-foot
(of electrode surface), and these figures are normally several
hundreds of amperes for a typical fuel cell configuration.
To understand just what all the noise is about, let's take
a quick look at conventional batteries and the way they produce
electricity. Dry cells, whether of the zinc-carbon type used
in flashlights or the more sophisticated alkaline variety, all
produce electric current by means of the chemical reaction that
goes on between certain key materials - the electrodes and the
electrolyte. The electrolyte is a liquid or semiliquid that
reacts chemically with the negative electrode, usually zinc,
producing many free electrons. The electron stream returns through
the load to the positive electrode and moves through the electrolyte
to the negative electrode where the electrons are again freed
by the chemical action.
This chemical action consumes both the negative electrode
and the electrolyte. In dry cells, the result is a dropping
off of the cell's productivity; eventually the cell must be
discarded. In wet-cell batteries such as the automotive type,
if the consumption of negative electrode and electrolyte has
not progressed too far, the chemical action can be reversed
by applying a direct current to the battery terminals to recharge
it. The ability to be recharged draws a distinct line between
two battery types. Primary batteries cannot be recharged; secondary
Enter the Fuel Cell.
Although there are many similarities between a fuel cell
and a primary battery, the big difference is that the electrodes
and electrolyte used in the fuel cell are not changed or consumed
during the operating life of the device.
The 12" x 14" fuel cell module uses economical
carbon electrodes combined with a minimum of precious metal
catalyst. Made by Union Carbide, it is a hydrogen-oxygen low-temperature
The zinc (or magnesium or lead) electrode used at the anode
in a primary battery cell actually serves two purposes - that
of an electrode and that of a "fuel" which is consumed as the
cell wears out. The electrodes used in a fuel cell are not used
as fuel. The fuel-hydrogen, hydrocarbons, etc. - is continuously
fed to the cell from an external source.
A hydrogen-oxygen fuel cell, circa 1959,
shows immense progress that has been made in a few years. Object
at right of G.E. cell is a motor with a propeller.
A recent development is a cell that uses
inexpensive hydrocarbon fuels and oxygen. Devised by Dr. Thomas
Grubb and Dr. Leonard Niedrach of G.E., the cells shown below
operate on such fuels as diesel oil, gasoline, and propane gas.
As shown in the generalized drawing of a fuel cell (p. 48),
the chemical reactions that produce a flow of electrons in the
external circuit take place in the cell's porous catalytic electrodes.
This terminology largely explains the function of the electrodes:
they absorb fuel and oxidant by virtue of being porous, and
promote a reaction between the two which generates electricity.
Producing the perfect electrode for fuel cells is one of the
big problems that has stumped researchers ever since a brilliant
scientist, W. R. Grove, conducted experiments with elementary
fuel cells back in 1839. Carbon and polymer plastics have been
used for electrodes. More recently, spongy platinum and nickel
boride have come along. Without laboring the point, producing
economical electrodes that can promote and contain fuel cell
reactions without themselves changing is no mean trick.
This experimental high-temperature fuel cell
uses a solid zirconia electrolyte (white cylinder). The dark
cylinder is a graphite electrode. Cell uses natural gas and
oxygen to generate electricity.
In operation, the two electrodes of a hydrogen-oxygen fuel
cell absorb their gases by diffusion, the anode taking on oxygen
and the cathode hydrogen. The two electrodes are separated by
a liquid or solid electrolyte, and the reaction takes place
at the surface where the electrolyte makes contact with the
A cutaway mockup of one of the fuel cell
canisters installed in Gemini. Fuel cell modules - the first
may be in orbit when you read this - produce drinking water
for astronauts as well as up to two kilowatts of electrical
When the oxidant (air or oxygen) reaches the cathode of the
fuel cell, it is absorbed by the cathode and enters the electrolyte
in a process called "sorption." The exact mechanism by which
sorption (a general term meaning the same as "absorption" but
used when the phenomenon is unknown or indefinite) of the oxygen
takes place remains one of the mysteries of fuel cell operation.
On reaching the anode, the oxygen combines with the fuel absorbed
by the anode and oxidizes it, producing electricity in the process.
This fuel-cell-driven golf cart made by Allis-Chalmers
shows the feasibility of putting fuel cells to work powering
vehicles. A fuel-cell-operated farm tractor was demonstrated
by firm as early as 1959.
Amazing as it may seem, no heat is produced other than a
small amount due to electrochemical inefficiencies. The fuel
cell thus becomes the world's most perfect generator of electricity.
With no. moving parts and no energy-wasting boiler-turbine combinations
which convert fuel by burning it, the fuel cell strips electrons
from the fuel and sends them into an external circuit to do
A classroom demonstrator of fuel cell principles,
this working model created by Allis-Chalmers uses either alcohol
or sodium or potassium hydroxide as fuel, and hydrogen peroxide
as an oxidant. Platinum, silver, and nickel electrode plates
are positioned in tank at right, and the two end plates connected
to the miniature electric motor furnished with the model. Priced
at $9.75, model is available from Science Materials Center.
Inc., 220 East 23 St., New York, N.Y. 10010, less necessary
Referring back to the fuel cell drawing, the stripped atoms
of fuel, now positive ions, migrate back through the electrolyte
to the cathode where they combine with the oxidant to produce
water, a "waste" product which, incidentally, may prove very
useful. Depending on the fuel used a waste product is also produced
on the anode side of the fuel cell; in the case of hydrocarbons,
this is carbon dioxide as in a gasoline engine. Unlike a gasoline
engine, however, which may have at most a conversion efficiency
of 30 to 40 percent, the fuel cell has efficiencies of 50 to
60 percent at present, and theoretical levels up to 98 percent.
Another big fuel cell advantage is that air can be used as
the oxidizing gas. This completely eliminates the need for a
separate oxygen supply for cells operating anywhere on the earth's
surface. Of course, cells lofted into outer space must carry
their oxygen. The one disadvantage of using air is the lower
productivity that results. When a cell is pressurized, the available
yield in amperes per square foot of electrode goes up. As the
device operates, its temperature also goes up (due to the inefficiencies
mentioned earlier) which further raises the yield.
While fuel cells using inexpensive hydrocarbon fuel (i.e.,
anything from natural gas to gasoline to diesel fuel) hold the
most promise for future down-to-earth commercial applications
there is still a great deal of developmental work ahead. One
of the major obstacles is the high cost of the platinum alloy
electrode material which seems to hold the key to making these
inexpensive fuels react to produce electricity in a fuel cell.
Raising the operating temperature raises the cell's output,
but with one bad side effect - it causes corrosive action at
the electrodes, a condition that can ruin the cell after a relatively
short time. But the advantages of elevated temperatures can
be retained by the use of a solid electrolyte designed to withstand
them. One such material in use is lime-stabilized zirconia.
In a cell of this type, a fuel such as methane (natural gas)
is fed to one side of the cell where it forms carbon on the
electrolyte surface. The carbon becomes both the anode and the
fuel. The operating temperature of this cell is normally about
1800° F (about 985° C). This temperature is above the
melting point of silver and it is molten silver which forms
the base for the negative electrode. Oxygen is diffused into
the silver, and the high operating temperature is maintained
simply by burning off gases within the cell. High-temperature
cells in this category have produced current densities up to
150 amperes per square foot of electrode area. Nominal voltage
for such a cell is 0.7 volt, making the single-cell power output
a little over 100 watts per square foot of electrode.
A further development that is still being evaluated is known
as the "Redox" (reduction and oxidation) cell. This device involves
a two-step process in which an intermediate gas-liquid reaction
occurs in the electrolyte itself. The Redox cell, although it
isn't as efficient as the more conventional types, has lower
internal resistance losses which more than offset the lower
efficiency level. It is still largely experimental, however.
Fuel Cells in Outer Space.
The state of the art has advanced sufficiently in certain
cell types to make it possible to use fuel cells in space vehicles.
Several experimental devices have been lofted into outer space
as part of a testing and evaluation program. The units tested
have shown virtually no effects from prolonged periods of weightlessness
and high-gravity acceleration and deceleration. Cells recovered
from space probes have continued to function normally in laboratory
life tests, still operating at optimum efficiency.
In fact, the space testing has been so successful that G.E.
is now building fuel-cell modules for use in the Gemini space
program at the rate of one complete system every two weeks.
The first systems have been delivered, and one is scheduled
for launching later this year - perhaps even as you read this
- as part of the equipment of the unmanned Gemini Number Two
The Gemini system is made up of twin canisters two feet long
and a foot in diameter, each containing 100 individual solid-electrolyte
(the electrolyte portion of each cell is known as an "ion-exchange
membrane") fuel cells. The system is highly reliable, has a
high power output (up to two kw.); and is much lighter in weight
(145 pounds not counting fuel) than any other comparable power
By way of comparison, a typical fuel cell system designed
to provide outputs of 500 watts to two kilowatts for 10,000
hours reliability weighs (including fuel) between 400 and 500
pounds. Solar cells and battery systems with comparable outputs
and reliability would weigh in the neighborhood of 700 pounds.
And solar cells have a further disadvantage. Because they must
be mounted externally on the space vehicle, they are especially
susceptible to damage by radiation and minor meteor collisions.
The twin cylinders installed in Gemini Two each contain three
fuel-cell stacks which can be operated separately depending
on power supply requirements. The fuels are stored at temperatures
near absolute zero, and waste heat generated within the cell
is carried off by a circulating cooling system. Another aspect
of the fuel cell is its by-product: potable water. In Gemini,
the water will be made available for consumption by the astronauts
who man future vehicles, thereby reducing the payload.
Compared with conventional power sources in size, weight,
and maintenance required, the fuel cell offers some enormous
advantages. In a typical military field application, such as
providing power for a front-line communications outpost, the
fuel cell is expected to surpass such power sources as primary
batteries, secondary batteries including nicads and wet-cell
storage types, and the frequently used gasoline-driven motor-generator.
The primary batteries have to be replaced frequently, especially
if they must deliver sustained current outputs for radio transmission.
Secondary batteries must be recharged. This means using a
noisy (and therefore frequently undesirable) motor generator
set or replacing the batteries at regular intervals with recharged
units brought up from the rear. The motor generator itself may
be too cumbersome to bring up to some positions, its noise of
operation can attract the enemy's attention, and it must be
constantly pampered, fueled and maintained.
The fuel cell is completely quiet in operation. It can deliver
sustained high current for indefinite periods of time, and it
is fueled with easily transported gases or liquids. In fact,
the total weight of a fuel cell system along with enough fuel
to run it for several weeks may be less than the weight of a
comparable set of storage batteries that require constant recharging.
And powerful they are. On the basis of present-day technology,
fuel cells will soon be able to deliver about a kilowatt for
every 15 to 20 pounds of weight! Yet another advantage of fuel
cells as compared to gasoline engines, for example, is that
fuel cell efficiency increases with partial loads, and under
no-load conditions, no fuel is consumed at all. This no-load
no-consumption feature separates the fuel cell from both engines
and conventional electro-chemical batteries. Any engine uses
fuel when it is idling.
Earthbound applications for fuel cells in the near future
include providing power for electric switching locomotives;
experts believe that such an all-electric system will be far
more efficient and easier to control than the conventional diesel-electrics
in common use today. Powering midget submarines is another potential
application, although the subs will have to carry a canned oxygen
supply for extended periods of deep under-surface travel; a
snorkel will provide air for shallow operation.
One of the most intriguing possible uses is in the electric
automobile. Several years ago, a major manufacturer of solar
cells exhumed a museum-piece electric car and covered its roof
with solar cells as a publicity stunt. The car ran beautifully
as long as the sun was shining. What was possible with primitive
turn-of-the-century batteries and today's solar cells will certainly
be feasible with fuel cells. If the car's cells use methane,
the car can be refueled simply by having the local power company
run a pipe for natural gas into the garage. Refueling on the
road will be done the same way, via natural gas outlets in filling
stations. And it'll be a lot cheaper than gasoline. There will
be far less maintenance required, too, since an electric motor
has just one moving part.
As a portable source of direct energy conversion, the fuel
cell appears to hold almost unlimited promise. Its ruggedness
and reliability have already been proven in the rigorous environments
of outer space and re-entry, and continuing tests indicate an
almost incredible lifespan for this electrochemical generating
Posted August 15, 2013