The Fuel Cell: is it ready?
By Isidor Buchmann, President, Cadex Electronics
Battery experts agree that the battery,
as we know it today, will remain a ‘weak link’ for the foreseeable
future. Given its relatively short life span, the battery
is also the most expensive and least reliable component of
a portable device.
An innovative new approach will be needed
to satisfy the ever-increasing thirst for mobile power. The
ideal battery, which would provide an inexhaustible pool of
energy carried in a small package, is still far from reality.
Will this miracle battery be based on the classic electro-chemical
concept, the evolving fuel cell or some groundbreaking new
technology? This answer is anyone’s guess.
In this article we focus on the emerging
fuel cell and examine its suitability in stationary, mobile
and portable applications. But first we make some general
cost comparisons on available power sources.
Among the common power sources, energy
from non-rechargeable batteries is the most expensive. This
cost increases with smaller battery sizes. Figure 1 reflects
the cost per kWh using non-rechargeable batteries, also referred
to as primary batteries.
per Cell (US$)
Figure 1: Energy
and Cost Comparison of Primary Alkaline Cells.
from primary batteries is most expensive. The cost increases
with smaller battery sizes.
Figure 2 evaluates the cost to generate
one kilowatt (kW) of energy by means of a rechargeable battery,
combustion engine, fuel cell and electricity from the utility
grid. We take into account the initial investment, add the
fuel consumption and include the eventual replacement of each
Power obtained through the electrical utility
grid is most cost effective. Consumers in industrialized countries
pay between $0.05 and 0.10US per kWh. The typical daily energy
consumption of a household is 25 kilowatt-hour (kWh).
of equipment to generate 1kW
of equipment before major overhaul or replacement
Cost of fuel
per kWh, incl. fuel, maintenance and equipment replacement.
For portable use
based on 7.2V, 1000mAh at $50/pack
| 1500 h
based on 1C discharge
electricity for charging
For mobile use
based on $3,000/100kW (134HP)
For stationary use
based on $4,000/100kW (134HP)
| 5000 h
$3,000 – 7,500
From electric grid
| All inclusive
|| All inclusive
Figure 2: Cost Comparison
to generate one kilowatt (kW) of energy,
taking into account the initial investment, fuel consumption,
maintenance and eventual replacement of the equipment.
The costing information
on the fuel cell is based on current estimates. Lower material
costs and volume production will eventually moderate these
The Fuel Cell
A fuel cell is an electrochemical device, which combines
hydrogen fuel with oxygen to produce electric power, heat
and water. In many ways, the fuel cell resembles a battery.
Rather than applying a periodic recharge, a continuous supply
of oxygen and hydrogen is supplied from the outside. Oxygen
is drawn from the air and hydrogen is carried as fuel in a
pressurized container. As alternative fuel, methanol, propane,
butane and natural gas can be used.
The fuel cell does not generate energy through burning;
rather, it is based on an electrochemical process. There are
little or no harmful emissions. The only release is clean
water. In fact, the water is so pure that visitors to Vancouver’s
Ballard Power Systems drank clear water emitted from the tailpipes
of buses powered by a Ballard fuel cell.
The fuel cell is twice as efficient in energy conversion
through a chemical process than through combustion. Hydrogen,
the simplest element consisting of one proton and one electron,
is plentiful and is exceptionally clean as a fuel. Hydrogen
makes up 90 percent of the composition of the universe and
is the third most abundant element on the earth’s surface.
Such a wealth of fuel would provide an almost unlimited pool
of energy at relatively low cost. But there is a price to
pay. The fuel cell core (or stack), which converts oxygen
and hydrogen to electricity, is expensive to build and maintain.
Hydrogen must be carried in a pressurized bottle. If propane,
natural gas or diesel is used, a reformer is needed to extract
the hydrogen. Reformers for PEMs are bulky and expensive.
They start slowly and purification is required. Often the
hydrogen is delivered at low pressure and additional compression
is required. Some fuel efficiency is lost and a certain amount
of pollution is produced. However, these pollutants are typically
90 percent less than what comes from the tailpipe of a car.
The fuel cell concept was developed in 1839 by Sir William
Grove, a Welsh judge and gentleman scientist. The invention
never took off, partly because of the success of the internal
combustion engine. It was not until the second half of the
20th century when scientists learned how to better utilize
materials such as platinum and Teflon, that the fuel
cell could be put to practical use.
A fuel cell can be thought of as electrolysis in reverse,
using two electrodes separated by an electrolyte. Hydrogen
is presented to the negative electrode (anode) and oxygen
to the positive electrode (cathode). A catalyst at the anode
separates the hydrogen into positively charged hydrogen ions
and negatively charged electrons. On the PEM system, the hydrogen
is catalyzed; the smaller protons migrate across the membrane
to the cathode where they combine with oxygen to produce water
and heat. The electrodes pick up the electrons to produce
an electric current. A single fuel cell produces 0.6 to 0.8V
under load. Several cells are connected in series to obtain
The first practical application of the fuel cell system
was made in the 1960s during the Gemini space program, when
this power source was favored over nuclear or solar power.
The fuel cell, based on the alkaline system, generated electricity
and produced the astronauts’ drinking water. Commercial
application of this power source was prohibitive at that time
because of the high cost of materials. In the early 1990s,
improvements were made in stack design, which led to increased
power densities and reduced platinum loadings at the electrodes.
High cost did not hinder Dr. Karl Kordesch, the
co-inventor of the alkaline battery, to convert his car to
an alkaline fuel cell in the early 1970s. Dr. Kordesch drove
the car for many years in Ohio, USA. The hydrogen tank was
placed on the roof and the trunk was utilized to store the
fuel cell and back-up batteries. According to Dr. Kordesch,
there was enough room for four people and a dog.
Type of fuel cells — Several variations of fuel
cell systems have emerged. The most common are the previously
mentioned and most widely developed PEM System using a polymer
electrolyte. This system is aimed at vehicles and portable
electronics. Several developers are also targeting stationary
applications. The Alkaline System, which uses a liquid electrolyte,
is the preferred fuel cell for aerospace applications, including
the Space Shuttle. Molten Carbonate, Phosphoric Acid and Solid
Oxide Fuel Cells are reserved for stationary applications,
such as power generating plants for electric utilities. Among
these stationary systems, the Solid Oxide is the least developed
but has received renewed attention due to breakthroughs in
cell material and stack designs. Figure 3 compares the most
common fuel cell systems in development.
Exchange Membrane (PEMFC)
|| Mobile (buses, cars), portable
power, medium to large-scale stationary power generation
|| Compact design; relatively long
operating life; adapted by major automakers; offers quick
start-up, low temperature operation, operates at 50% efficiency
|| High manufacturing costs, needs
heavy auxiliary equipment and pure hydrogen, no tolerance
for contaminates; complex heat and water management.
|| Most widely developed; limited
production; offers promising technology.
| Space (NASA),
terrestrial transport (German submarines).
|| Low manufacturing
and operation costs; does not need heavy compressor, fast
|| Large size;
needs pure hydrogen and oxygen; use of corrosive liquid
|| First generation
technology; has renewed interest due to low operating
| Large-scale power generation.
|| Highly efficient; utilizes heat
to run turbines for co-generation.
|| Electrolyte instability; limited
|| Well developed; semi-commercial
| Medium to
large-scale power generation.
available; lenient to fuels; utilizes heat for co-generation.
|| Low efficiency,
limited service life, expensive catalyst.
|| Mature but
faces competition from PEMFC.
|| Medium to large-scale power
|| High efficiency, lenient to
fuels, takes natural gas directly, no reformer needed.
Operates at 60% efficiency; utilizes heat for co-generation.
|| High operating temperature;
requires exotic metals, high manufacturing costs, oxidation
issues; low specific power.
|| Least developed. Breakthroughs
in cell material and stack design sets off new research.
| Suitable for
portable, mobile and stationary applications.
|| Compact design,
no compressor or humidification needed; feeds directly
off methanol in liquid form.
|| Complex stack
structure, slow load response times; operates at 20% efficiency.
Figure 3: Advantages and disadvantages
of the various fuel cell systems.
The PEM is the most widely
developed system today.
The PEM system allows compact designs and achieves a high
energy to weight ratio. Another advantage is a quick start-up
when hydrogen is applied. The stack runs at a relatively low
temperature of about 80°C (176°F). The efficiency is approximately
50 percent. (In comparison, the internal compaction motor
has an efficiency of about 15%).
The limitations of the PEM system are high manufacturing
costs and complex water management issues. The stack contains
hydrogen, oxygen and water. If dry, the input resistance is
high and water must be added to get the system going. Too
much water causes flooding.
The PEM fuel cell has a limited temperature range. Freezing
water can damage the stack. Heating elements are needed to
keep the stack within an acceptable temperature range. The
warm-up is slow and the performance is poor when cold. Heat
is also a concern if the temperature rises too high.
The PEM fuel cell requires heavy accessories. Operating
compressors, pumps and other apparatus consumes 30 percent
of the energy generated. The PEM stack has an estimated service
life of 4000 hours if operated in a vehicle. The relatively
short life span is caused by intermittent operation. Start
and stop conditions induce drying and wetting, which contributes
to membrane stress. If run continuously, the stationary stack
is good for about 40,000 hours. The replacement of the stack
is a major expense.
The PEM fuel cell requires pure hydrogen. There is little
tolerance for contaminates such as sulfur compounds or carbon
monoxide. Carbon monoxide can poison the system. A decomposition
of the membrane takes place if different grade fuels are used.
Testing and repairing a stack are difficult. The complexity
to service a fuel cell becomes apparent when considering that
a typical 150V, 50 kW stack contains about 250 cells.
1 kW Portable fuel
cell power generator.
The PEM fuel cell is
a fully automated power system, which converts hydrogen
fuel and oxygen from air directly into DC electricity.
Water is the only by-product of the reaction. This fuel
cell generator, which operates at low pressures, provides
reliable, clean, quiet and efficient power. It is small
enough to be carried to wherever power is needed.
Courtesy of Ballard Power
Systems Inc. [February 2001]
The Solid Oxide Fuel Cell (SOFC) is best suited for stationary
applications. The system requires high operating temperatures
(about 1000°C). Newer systems are being developed which can
run at about 700°C.
A significant advantage of the SOFC is its leniency to
fuel. Due to the high operating temperature, hydrogen is produced
through a catalytic reforming process. This eliminates the
need for an external reformer to generate hydrogen. Carbon
monoxide, a contaminant in the PEM systems, is a fuel for
the SOFC. In addition, the SOFC system offers a fuel efficiency
of 60 percent, one of the highest among fuel cells.
Higher stack temperatures demand specialized and exotic
materials, which adds to manufacturing costs. Heat also presents
a challenge for longevity and reliability because of increased
material oxidation and stress. However, high temperatures
offer a benefit by enabling co-generation by running steam
generators. This improves the overall efficiency of this fuel
The Alkaline Fuel Cell (AFC) has received renewed interest
because of low operating cost. Although larger in physical
size than the PEM system, the alkaline fuel cell has the potential
of lower manufacturing and operating costs. The water management
is simpler, no compressor is usually needed, and the hardware
is cheaper. Whereas the separator for the PEM stack costs
between $800 and $1,100US per square meter, the equivalent
of the alkaline system is almost negligible. (In comparison,
the separator of a lead acid battery is $5 per square meter.)
Operating costs of $100 to 200 per kW are feasible. Start
and stop (wetting and drying) is more forgiving than with
most other systems.
As a negative, the ALFC needs pure oxygen and hydrogen
to operate. The amount of carbon dioxide in the air can poison
the alkaline fuel cell. It should be noted, however, that
carbon dioxide is easier to scrub than carbon monoxide, a
deterrent of the PEM system.
Applications — The fuel cell is being considered
as an eventual replacement for the internal combustion engine
for cars, trucks and buses. Major car manufacturers have teamed
up with fuel cell research centers or are doing their own
development. There are plans for mass-producing cars running
on fuel cells. Because of the low operating cost of the combustion
engine, and some unresolved technical challenges of the fuel
cell, however, experts predict that a large scale implementation
of the fuel cell to power cars will not occur before 2015,
or even 2020.
Large power plants running in the 40,000 kW range will
likely out-pace the automotive industry. Such systems could
provide electricity to remote locations within 10 years. Many
of these regions have an abundance of fossil fuel that could
be utilized. The stack on these large power plants would last
longer than in mobile applications because of steady use,
even operating temperatures and absence of shock and vibration.
Residential power supplies are also being tested. Such
a unit would sit in the basement or outside the house, similar
to an air-conditioning unit of a typical middle class North
American home. The fuel would be natural gas or propane, a
commodity that is available in many urban settings.
Fuel cells may soon compete with batteries for portable
applications, such as laptop computers and mobile phones.
However, today’s technologies have limitations in meeting
the cost and size criteria for small portable devices. In
addition, the cost per watt-hour is less favorable for small
systems than large installations.
Let’s examine once more the cost to produce one kilowatt
(kW) of power. In Figure 3 we learned that the investment
to provide 1kW of power using rechargeable batteries is around
$7000US. This calculation is based on 7.2V; 1000mAh NiCd packs
costing $50 each. High energy-dense batteries that deliver
fewer cycles and are more expensive than the NiCd will double
The high cost of portable power opens vast opportunities
for the portable fuel cell. At an investment of $3,000 to
$7,500 to produce one kilowatt of power, however, the energy
generated by the fuel cell is only marginally less expensive
than that produced by conventional batteries.
Direct Methanol (DMFC), the fuel cell designed for portable
applications, would not necessarily replace the battery in
the equipment but serve as a charger that is carried separately.
The feasibility to build a mass-produced fuel cell that fits
into the form factor of a battery is still a few years away.
The advantages of the portable DMFC is: relatively high
energy density (up to five times that of a Li-ion battery);
liquefied fuel as energy supply, environmentally clean, fast
recharge and long runtimes. In fact, continuous operation
is feasible. Miniature fuel cells have been demonstrated that
operate at an efficiency of 20 percent and run for 3000 hours
before a stack replacement is necessary. There is some degradation
during the service life of the fuel cell. Portable fuels cells
are still in experimental stages.
Advantages and limitations of the fuel cell — A
less known limitation of the fuel cell is the marginal loading
characteristic. On a high current load, mass transport limitations
come into effect. Supplying air instead of pure oxygen aggregates
The issue of mass transport limitation is why the fuel
cell operates best at a 30 percent load factor. Higher loads
reduce the efficiency considerably. In terms of loading characteristics,
the fuel cell does not match the performance of a NiCd battery
or a diesel engine, which perfrom well at a 100 percent load
Ironically, the fuel cell will not eliminate the chemical
battery — but promote it. Similar to the argument that the
computer would make paper redundant, the fuel cell needs batteries
as a buffer. For many applications, a battery bank will provide
momentary high current loads and the fuel cell will serve
to keep the battery fully charged. For portable applications,
a supercapacitor will improve the loading characteristics
and enable high current pulses.
Most fuel cells are still handmade and are used for experimental
purposes. Fuel cell promoters remind the public that the cost
will come down once the cells are mass-produced and lower
cost material are found. While an internal combustion engine
requires an investment of $35 to $50 to produce one kilowatt
(kW) of power, the equivalent cost in a fuel cells is still
a whopping $3,000 to $7,500. The goal is a fuel cell that
would cost equal or less than diesel engines.
The fuel cell will find applications that lie beyond the
reach of the internal combustion engine. Once low cost manufacturing
is feasible, this power source will transform the world and
bring great wealth potential to those who invest in this technology.
It is said that the fuel cell is as revolutionary in transforming
our technology as the microprocessor has been. Once fuel cell
technology has matured and is in common use, our quality of
life will improve and the environmental degradation caused
by burning fossil fuel will be reversed. It is generally known
that the maturing process of the fuel cell will not be as
rapid as that of microelectronics.
This article contains excerpts from the second edition book
entitled Batteries in a Portable World — A Handbook
on Rechargeable Batteries for Non-Engineers. In the book,
Mr. Buchmann evaluates the battery in everyday use and explains
their strength and weaknesses in laymen’s terms. The 300-page
book is available from Cadex Electronics Inc. through firstname.lastname@example.org,
tel. 604-231-7777 or most bookstores. For additional information
on battery technology and more detail on the book visit www.buchmann.ca.
Contributions have been made by Dr. Terrance Wong and Dr.
François Girard from the National Research Council in Canada,
as well as Dr. Karl Kordesch, co-inventor of the alkaline
battery and specialist in fuel cell technology.
About the Author
Isidor Buchmann is the founder and CEO of Cadex Electronics
Inc.in Vancouver, British Columbia, Canada. Mr. Buchmann has
a background in radio communications and has studied the behavior
of rechargeable batteries in practical, every day applications
for two decades. The author of many articles and books on
battery maintenance technology, Mr. Buchmann is a well-known
speaker who has delivered technical papers and presentations
at seminars and conferences around the world. He can be reached
at Tel: 604-231-7777; Fax: 604-2317755; E-mail: Isidor.Buchmann@cadex.com.
About the Company
Cadex Electronics Inc. is a world leader in the design
and manufacture of advanced battery analyzers and chargers.
Their award-winning products are used to prolong battery life
in wireless communications, emergency services, mobile computing,
avionics, biomedical, broadcasting and defense. Cadex products
are sold in over 100 countries.