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Zac Harder
Nelson Kilmer - Physics 203
Research Paper
3 October 2002
Beyond Batteries
Imagine a source of power that is quiet, efficient, clean, and requires no moving
parts. Imagine a source of power that has these qualities, and can be as big as a minivan, or as
small as credit card. Imagine a global market for this product grossing over $218 million a
year with a projected increase to $2.4 billion in three years time (BTI). This source of power
is called a fuel cell and has existed longer than any combustion engine.
Fuel cells are growing rapidly in popularity and have attracted the attention of many
electronic, automotive, and civil engineers. Fuel cells have a history of 164 years, come in
many different styles, shapes, sizes, and the applications are as numerous as the stars in the
sky (BTI).
William Robert Grove was an Englishman who lived from 1811 to 1896. Although he
was a lawyer by trade, he also expressed interests in science. He performed various
experiments, including those with fuel cells. In 1838, he modified a wet cell to contain a
platinum electrode immersed in nitric acid, and a zinc electrode immersed in zinc sulfate
(BTI). Grove found that by putting two platinum electrodes with one end of each in a
container of sulfuric acid, and the other ends separately sealed in containers of oxygen and
hydrogen, a current would flow between the electrodes. He called this the “Gas Battery.”
This “Gas Batter,” better known as a fuel cell, produced about 12 amps at about 1.8 volts
(BTI).
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Friedrich Wilhelm Ostwald (1853-1932) founded the field of physical chemistry. In
1893 he experimentally determined the relationship of the components of the fuel cell; the
anode, cathode, electrolytes, oxidizing and reducing agents, and anions and cations. Grove
had theorized about what actually took place in the cell but could not prove anything.
Ostwald proved what Grove lacked (BTI).
Francis Thomas Bacon (1904-1992) began researching fuel cells in the early 1930’s.
In 1932 he built a cell that utilized nickel gauze electrodes and operated under pressures as
high as 3000 pounds per square inch (psi) (BTI). During World War II he started researching
fuel cells that could be designed specifically for the Royal Navy submarines. In 1958 he
produced an alkali cell that utilized a stack of ten-inch diameter electrodes for Britain's
National Research Development Corporation. This cell proved reliable enough that it
attracted the attention of Pratt & Whitney. Pratt & Whitney borrowed this technology to
place into the Apollo space shuttle. The fuel cells produced power for the shuttle and also
drinking water for the crew (BTI).
There are many different styles and sizes of fuel cells. Even though there are many
different kinds of fuel cells, they all are generally the same. A fuel cell is a device that
generates electricity through a chemical equation. A fuel cell has two electrodes, one called
an anode, and the other called a cathode. Oxidation occurs at the anode and reduction occurs
at the cathode. Hydrogen molecules enter into the anode side of the cell and react with the
anode. The hydrogen ion’s move through the semi-permeable membrane or electrolyte and
react with oxygen from the air to form water. The separated electrons from the hydrogen
molecules flow from the anode through a conductor and load, such as a light bulb or electric
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motor, to the cathode. The source of hydrogen may be hydrogen, natural gas, methane, and
ethanol (UTCFC).
Different types of fuel cells may vary in what raw fuel they use, material of
electrolyte, material of electrode, and method of fuel conversion. The alkali fuel cell operates
on compressed hydrogen and oxygen. It utilizes potassium hydride (KOH) in water as an
electrolyte. The efficiency is about 70% and the operating temperature is about 150 to 200
degrees Celsius, which is about 300 to 400 degrees Fahrenheit. This type of cell can produce
between 300 watts (W) and 5 kilowatts (kW). Alkali cells require pure hydrogen fuel, which
is very explosive. The platinum electrode catalysts are very expensive and alkali cells over
all are prone to leakage (Sperry).
Molten Carbonate fuel cells (MCFC’s) use high temperature salt compounds such as
sodium or magnesium carbonates (CO3) as the electrolyte. Efficiencies range from 60 to 80%
and operating temperatures are about 650 degrees Celsius, which is about 1200 degrees
Fahrenheit. Current models can produce up to 2 megawatts (MW) and plans exist for designs
units producing as much as 100 MW. The extreme temperature eliminates the carbon
monoxide poisoning of the cell and the extra heat can be recaptured and recycled to make
additional energy. Nickel electrodes are much cheaper than platinum but the extreme heat
given off limits the variation of application. This factor would eliminate the automotive
industry or common house holds from possible utilization. The carbonates are used in the
reaction so carbonates must be injected occasionally, which also hinders ease of operation
(Sperry).
Phosphoric Acid fuel cells (PAFC’s) use phosphoric acid as the electrolyte and boast
efficiencies between 40 and 80%. The standard operating temperature varies between 150
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and 200 degrees Celsius, which is between 300 to 400 degrees Fahrenheit. Current output is
around 200 kW but units producing up to 11 MW have been tested. PAFC’s are beneficial to
the fuel cell industry because they can withstand fuels containing up to 1.5% carbon
monoxide (CO). This allows multiple types of fuels to be used. Gasoline may be used in such
a case, but requires the removal of the sulfur content. Platinum catalysts are required, which
are expensive, and rust resistant parts must be used inside due to the corrosive nature of the
acid (Sperry).
Proton Exchange Membrane fuel cells utilize a thin polymer electrolyte semipermeable sheet. Efficiencies can range from 40 to 50% and standard operating temperatures
are about 80 degrees Celsius, which is about 175 degrees Fahrenheit. These types of cells can
produce between 50 and 250 kW. The flexible electrolyte sheets will not leak or crack and
the whole cell operates at a temperature suitable for automobiles or homes. It requires
purified fuel and utilizes a platinum electrode on both sides of the membrane, which raises
the cost for the consumer (Sperry).
Solid Oxide fuel cells (SOFC’s) use a hard ceramic metal compound usually made of
calcium or zirconium oxides (O2) as an electrolyte. Efficiency is about 60% and standard
operating temperatures are around 1000 degrees Celsius, which is about 1800 degrees
Fahrenheit. A SOFC’s output may be as high as 100 kW. A reformer for the fuel is not
needed at such high temperatures. The high temperature limits the uses of this particular type
of fuel cell, and though the ceramic tile may not leak, it may crack (Sperry).
There are many different applications for fuel cells. They could be utilized anywhere
portable power is required, as well as stationary applications for backup or even primary
energy. Fuel cells can replace batteries in cell phones allowing power to last up to a month
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without recharging. Laptops and other electronic devices will be run for hours longer than the
current models. Applications requiring low amounts of power, such as hearing aids, meter
readers, or hotel locks will benefit from the usage of fuel cells. These types of fuel cells
generally run on ethanol, which is easily attained (Given).
More than 200 fuel cell systems have been installed world wide powering hotels,
hospitals, nursing homes, office buildings, schools, power plants, and one air port terminal.
In some cases the fuel cells are used for back up or emergency power, where as in other
instances they are used for the primary source of power. Fuel cells can reduce energy costs
by 20 to 40% in large buildings. Fuel cells also power landfills by giving power to the station
and using methane produce by the landfill as fuel for the cell (Given).
Fuel cells can be used in residential applications as well. They can be installed with
power grids, or they can be used independently from power grids in remote locations. Fuel
cells do not produce pollution, or noise pollution because they operate silently. They produce
heat, which can be used to heat buildings, or converted into extra energy, which boosts
efficiency. These types of fuel cells reform hydrogen from natural gas or propane (Given).
The automotive industry is currently utilizing this technology the most due to the race
for better gas mileage and smaller emissions. Cars with fuel cells, as well as hybrid cars
involving batteries and fuel cells will be released commercially as soon as 2004. All of the
major automobile manufacturers have or are testing fuel cell powered cars (BTI).
Fuel cells are growing rapidly in popularity and have attracted the attention of many
electronic, automotive, and civil engineers. Even though they have a long history, they have
finally arrived commercially, come in many different styles, shapes, sizes, and the
applications are as numerous as the stars in the sky.
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