CLASSIFICATIONS OF FUEL CELLS
MSE-5390-SPRING-2015
FUNDAMENTALS OF SUSTAINABLE ENERGY
UNIVERSITY OF TEXAS, ARLINGTON
By
MUSALI, DAKSHINI
KOTA, SHANMUKA PRASAD GUPTA
GROUP # 6
ABSTRACT
Fuel cells generate electricity and heat
during electrochemical reaction which
happens between the oxygen and hydrogen
to form the water. Fuel cell technology is a
promising way to provide energy for rural
areas where there is no access to the public
grid or where there is a huge cost of wiring
and transferring electricity. In addition,
applications with essential secure electrical
energy requirement such as uninterruptable
power supplies (UPS), power generation
stations and distributed systems can employ
fuel cells as their source of energy.
The
current
paper
includes
comparative study of basic design, working
principle, applications, advantages and
disadvantages of various technologies
available for fuel cells. In addition, technoeconomic features of hydrogen fuel cell
vehicle (FCV) and internal combustion
engine vehicles (ICEV) are compared. The
results indicate that fuel cell systems have
simple design, high reliability, noiseless
operation, high efficiency and less
environmentally impact.
INTRODUCTION
Fuel cells are basically open
thermodynamics systems. They operate on
the basis of electrochemical reactions and
consume reactant from an external source.
They are favorable alternatives to
conventional electricity generation methods
for small scale applications. Hydrogen and
hydrocarbon fuels contain significant
chemical energy in comparison with
conventional battery materials; hence they
are now widely developed for numerous
energy applications.
Fuel cell technology is a promising
substitute for fossil fuels to provide energy
for rural areas where there is no access to
the public grid or huge cost of wiring and
transferring electricity is required. In
addition, applications with essential secure
electrical energy requirement such as
uninterruptible power supplies (UPS), power
generation stations and distributed systems
can employ fuel cells as their source of
energy. Fuel cell systems perform with the
highest efficiency compared to conventional
distributed energy systems. They have
simple design and reliable operation as well.
In addition, utilizing hydrogen as the
reactant makes them the most environmentally clean and noiseless energy
systems. Currently, fuel cell systems are
employed widely in small scale as well as
large scale applications such as combined
heat and power (CHP) systems, mobile
power systems, portable computers and
military communication equipment. Despite
all the advantages, there are some
limitations for utilizing fuel cells. For
example, life span of fuel cells shortens by
pulse demands and impurities of gas stream.
Low power density per volume, less
accessibility and less durability are other
challenges for fuel cell technology
development. Though, great break through
is yet to be seen, positive progress is
witnessed throughout the recent years.
HISTORY
the membrane, which served as catalyst for
The first references to hydrogen fuel cells
appeared in 1838. In a letter dated October
1838 but published in the December 1838
edition of The London and Edinburgh
Philosophical Magazine and Journal of
Science,
Welsh
physicist
and
barrister William Grove wrote about the
development of his first crude fuel cells. He
used a combination of sheet iron, copper and
porcelain plates, and a solution of sulphate
of copper and dilute acid. In a letter to the
same publication written in December 1838
but published in June 1839, German
physicist Christian
Friedrich
Schönbein discussed the first crude fuel cell
that he had invented. His letter discussed
current
generated
from
hydrogen
and
oxygen dissolved in water. Grove later
sketched his design, in 1842, in the same
journal. The fuel cell he made used similar
materials to today's phosphoric-acid fuel
cell.
oxygen reduction reactions. This became
known
as
Bacon successfully
developed
a
5 kW
stationary fuel cell. In 1955, W. Thomas
Grubb, a chemist working for the General
Electric Company (GE), further modified
the original fuel cell design by using a
polystyrene
ion-exchange
membrane as the electrolyte. Three years
later another GE chemist, Leonard Niedrach,
devised a way of depositing platinum onto
the
"Grubb-Niedrach
fuel
cell". GE went on to develop this technology
with NASA and McDonnell Aircraft, leading
to its use during Project Gemini. This was
the first commercial use of a fuel cell. In
1959, a team led by Harry Ihrig built a
15 kW fuel cell tractor for Allis-Chalmers,
which was demonstrated across the U.S. at
state fairs. This system used potassium
hydroxide as the electrolyte and compressed
hydrogen and oxygen as the reactants. Later
in
1959,
Bacon
and
his
colleagues
demonstrated a practical five-kilowatt unit
capable of powering a welding machine. In
the 1960s, Pratt and Whitney licensed
Bacon's U.S. patents for use in the U.S.
space program to supply electricity and
drinking water (hydrogen and oxygen being
readily available from the spacecraft tanks).
In 1991, the first hydrogen fuel cell
automobile
In 1939, British engineer Francis Thomas
sulphonated
the necessary hydrogen oxidation and
was
developed
by
Roger
Billings.
UTC Power was the first company to
manufacture and commercialize a large,
stationary fuel cell system for use as a cogeneration power
plant
in
hospitals,
universities and large office buildings.
WORKING PRINCIPLE:
Fuel cells generate electricity and heat via
electro chemical reaction which is actually
the reversed electrolysis reaction. It happens
between the oxygen and hydrogen to form
the water. There are a range of designs
available for fuel cells; however, they all
operate with the same basic principles. The
main difference in various fuel cell designs
is the chemical characteristics of the
Nevertheless, fuel cells of ten produce only
electrolyte. The electrochemical reaction
very small amount of current due to
depicts the operating principle of a fuel cell.
diminutive contact area between electrodes,
electrolyte and the gas. Another problem to
2H2 (g) +O2 (g) → 2H2O + energy
be considered is the distance between
Hydrogen + oxygen → water + (electrical
power + heat)
cathode, electrolyte and the external circuit.
At the anode, hydrogen is oxidized in to
protons and electrons, while at the cathode
oxygen is reduced to oxide species and
reacts to form water. Depending on the
electrolyte, either protons or oxide ions are
electron
through
insulating
an
ion
conductor
electrolyte
while
electrons travel through an external circuit to
deliver electric power.
cells and maximize the contact area, a thin
layer
A fuel cell has four main parts: anode,
transported
electrodes. To improve the efficiency of fuel
of
electrolyte
with
flat
porous
electrodes is considered for electrolyte and
the gas penetration. The reaction between
oxygen and hydrogen to generate electricity
is different for various types of fuel cells. In
an acid electrolyte fuel cell, electrons and
protons (H+) are released from hydrogen
gas ionizing at the anode electrode. The
generated electrons pass though an electrical
circuit and travel to the cathode while
protons are delivered via electrolyte. This
exchange
releases
electrical
energy.
Simultaneously at the cathode side, the
water is forming as a result of the reaction
between electrons
from electrode and
protons from electrolyte. The reactions
happening at the anode and cathode are
Anode: 2H2→4H++4e−
Cathode: O2+4e−+4H+→2H2O
Activation
drop due
Loss,
to
Ohmic
resistance
loss
of
(voltage
the
cell
Acid electrolytes and certain polymers that
components and interconnections), Mass
contain free H+ ions are often called “proton
transport loss (depletion of reactants at
exchange membranes”. They serve more
catalyst sites under high loads, causing rapid
properly
proton
loss of voltage). To deliver the desired
delivering functions since they solely allow
amount of energy, the fuel cells can be
the H+ ions passing through it. The
combined in series to yield higher voltage,
electrical current is lost in the case of
and in parallel to allow a higher current to
delivering electrons through the electrolyte.
be supplied. Such a design is called a fuel
and
effectively
for
cell stack. The cell surface area can also be
increased, to allow higher current from each
cell. Within the stack, reactant gases must be
distributed uniformly over each of the cells
DESIGN FEATURES
to maximize the power output
The most important design features in a fuel
TYPES OF FUEL CELLS
cell are:
Fuel cells are different according to
The electrolyte substance. The electrolyte
their
substance usually defines the type of fuel
applications and costs. They are classified
cell.The fuel that is used. The most common
based on the choice of fuel and electrolyte in
fuel is hydrogen.The anode catalyst breaks
to 6 major groups
down the fuel into electrons and ions. The
anode catalyst is usually made up of very
fine platinum powder.The cathode catalyst
turns the ions into the waste chemicals like
water or carbon dioxide. The cathode
catalyst is often made up of nickel but it can
also be a nano material-based catalyst.A
typical fuel cell produces a voltage from 0.6
V to 0.7 V at full rated load.
Voltage decreases as current increases, due
to several factors:
Direct methanol fuel cell(DMFC)
AFCs generally perform in temperatures
between 60 and 90. However, recent designs
ALKALINE FUEL CELL (AFC)
can operate at low temperatures between 23
The AFC generate electric power by
utilizing
alkaline
electrolyte
potassium
hydroxide (KOH) in water based solution.
and 70. AFCs are classified as low operating
temperature fuel cells with low cost
catalysts. The most common catalyst to
speed up electro chemical reactions in
cathode and anodes in this type of fuel cell
is nickel. Electrical efficiency of AFCs is
about 60% and CHP efficiency is more than
80%. They can generate electricity up to
20k. NASA has first used AFCs to supply
drinking water and electric power to the
The presence of the hydroxyl ions travelling
across the electrolyte allows a circuit to be
made and electrical energy could be
extracted. At anode, 2 hydrogen gas
molecules are combined with 4 hydroxyl
ions with a negative charge to release 4
water molecules and 4 electrons. The redox
reaction taking place is oxidation.
shuttle missions for space applications.
Currently, they are employed in submarines,
boats,
fork
lift
trucks
and
nichetran
sportation applications. AFCs are considered
as the most cost efficient type of fuel cells
since the electrolyte used is a standard
chemical potassium hydroxide (KOH). The
catalyst for the electrodes is nickel which is
not expensive compared with other types of
catalysts. AFCs have simple structures due
Oxidation: 2H2 + 4OH− → 4H2O + 4e−
to eliminating bi polar plates. They consume
Electrons released in this reaction, reach the
hydrogen and pure oxygen to produce
cathode through the external circuit and
portable water, heat and electricity sources.
react with water to generate (OH−) ions.
The by-product water produced by AFC is
the drinking water which is very useful in
At cathode, oxygen molecule and 2 water
space crafts and space shuttle fleets. They
molecules
4
have no green house gas emissions and
electrons to form 4 negatively charged
operate with a high efficiency of about 70%.
hydroxyl ions. The occurring redox reaction
In spite of all the advantages of AFCs, they
is reduction.
are defeated by getting easily poisoned with
combined
and
absorbed
Reduction: O2 + 2H2O + 4e− → 4OH−
carbon dioxide. The water based alkaline
solution (KOH) used in AFCs as electrolyte,
operation and system start up is a concern at
absorbs CO2 through the conversion of KOH
40◦C due to Phosphoric acid fuel cell
to
and
(PAFC). Solidity of phosphoric acid at this
cell.
temperature.
potassium
consequently
carbonate
poisons
(K2CO3)
the
fuel
Therefore, AFCs typically use purified air or
pure oxygen which in turn increases the
operating costs. Hence, one concern is to
find a substitute for KOH.
PHOSPHORIC
ACID
FUEL
CELL
(PAFC)
Phosphoric acid fuel cells (PAFC) use
carbon
paper
electrodes
and
liquid
phosphoric acid (H3PO4) electrolyte.
The hydrogen expelled at the anode splits in
to its 4 protons and 4 electrons. The redox
reaction taking place in anode is oxidation.
While at cathode, the redox reaction is
H3PO4 (3.09%H, 31.6%P, 65.3%O) is a clear
reduction where 4 protons and 4 electrons
colorless
combine with the oxygen to form water.
liquid
detergents,
food
used
in
fertilizers,
flavouring
and
pharmaceuticals. The ionic conductivity of
phosphoric acid is low at low temperatures,
so PAFC can operate at the range of 150–
220◦C temperature. The charge carrier in
The electrons and protons pass through the
this type of fuel cell is the hydrogen ion (H+
external
circuit
and
the
electrolyte,
respectively. The result is generation of
Or proton). They pass from the anode to the
electrical current and heat. The heat is
cathode through the electrolyte and the
usually exploited for water heating or steam
expelled electrons return to the cathode
generation
at
through the external circuit and generate the
however,
steam
electrical current. At the cathode side, water
produces one carbon monoxide (CO) around
is forming as the result of the reaction
the electrodes which might poison the fuel
between electrons, protons and oxygen with
cell and affect the PAFC performance. The
presence of platinum catalyst to speed up
solution to reduce the CO absorption is to
there actions. Expelled water is usually used
increase the anode temperature tolerance.
in
The higher tolerance for CO means higher
heating
applications.
Continuous
atmospheric
pressure;
reforming
reactions
temperature tolerance at anode. At high
Solid oxide fuel cells (SOFCs) are high
temperatures, the CO is desorbed in reversed
temperature fuel cells with metallic oxide
electro-catalyst reaction at cathode. Contrary
solid ceramic electrolyte. SOFCs generally
to other acid electrolytes that need water for
use a mixture of hydrogen and carbon
conductivity, PAFC concentrated phosphoric
monoxide formed by internally reforming
acid electrolyte is capable of operating in
hydro carbon fuel and air as the oxidant in
temperatures higher than boiling point
the fuel cell. Yttria stabilized zirconia
of water. PAFC does not require pure
oxygen for its operation since CO2 does not
(YSZ)
is
the
most
commonly
used
affect the electrolyte or cell performance.
electrolyte for SOFCs because of its high
They run on air and can be easily operated
chemical and thermal stability and pure
with reformed fossil fuels. Besides, H3PO4
ionic conductivity.
has lower volatility and long term stability.
The initial cost is high since PAFC uses air
with 21% oxygen instead of pure oxygen
resulting in 3 times reduction in the current
density. Therefore, PAFC is designed in
stack bipolar plate to increase electrode area
for more energy production which implies
high
initial
cost
for
this
technology.
Currently, PAFC systems are in commercial
stage with capacity up to 200kW and
systems with higher capacities (11MW) are
already tested. The PAFCs are expensive to
manufacture due to the need for finely
dispersed platinum catalyst coating the
electrodes. Unlike AFCs, hydrogen steam
impurity (CO2) does not affect the PAFCs.
Oxygen is oxidized in reduction reaction at
the cathode (air electrode) at1000◦C, while,
fuel oxidation happens at the anode. The
anode should be porous to conduct fuel and
transport the products of fuel oxidation away
from the electrolyte and fuel electrode
interfaces.
Oxidation: (1/2) O2 (g) + 2e− → O2− (s)
Electrical efficiency of this type of fuel cells
Reduction: O2− (S) + H2 (g) → H2O (g) +
is between 40 and 50% and CHP efficiency
2e−
about 85%. They are typically used for
onsite stationary applications.
SOFCs are well adopted with large scale
distributed power generation systems with
SOLID OXIDE FUEL CELL (SOFC)
capacity of hundreds of MWs.
The byproduct heat is usually used to
generate more electricity by turning gas
turbines and hence increasing the CHP
efficiency between 70 and 80%. SOFC
systems are reliable, modular and fuel
adaptable with low harmful gas (NO x and
SO x) emissions. They can be considered as
local power generation systems for rural
In MCFC, the reaction at the hydrogen
areas with no access to public grids.
electrode occurs between hydrogen fuel and
Furthermore, they have noise free operation
carbonate ion, which react to form carbon
and low maintenance costs. On the other
dioxide, water and electrons. At the anode,
hand, long start-up and cooling-down times
the feed gas usually
as well as various mechanical and chemical
compatibility issues limit the use of SOFCs.
Methane CH4 and water H2O are converted
Possible solutions to reduce the operating
to hydrogen (H2), carbon monoxide (CO)
temperature and claimed if successful and
and carbon dioxide (CO2).
sustainable counter measures are builtup,
SOFC may bring energy production to a
Reform1: CH4 + H2O → CO + 3H2
new generation.
Reform2: CO + H2O → CO2 + H2
MOLTEN CARBONATE FUEL CELL
Simultaneously,
(MCFC)
reactions consume hydrogen and carbon
Molten carbonate fuel cells (MCFCs) are
high temperature fuel cells. They use molten
carbonate
salt
mixture
as
electrolyte
two
electro
chemical
monoxide and generate electrons at anode.
Both reactions use carbonate ions (CO 32−)
available in the electrolyte.
suspended in a porous, chemically inert
Oxidation1: H2 + CO32− → H2O + CO2 +
ceramic matrix of beta alumina solid
2e−
electrolyte (BASE).
Oxidation2: CO + CO32− → 2CO2 + 2e−
The reduction happens at cathode and expels
new carbonate ions from oxygen (O2) and
carbon
dioxide
(CO2).
Here
by, the
carbonate ions produced at cathode are
transferred through the electrolyte to the
Cathode: (1/2) O2 (g) + 2H+ + 2e− → H2O
anode. Electric current and cell voltage can
Over all reaction: H2 (g) + (1/2) O2 (g) →
be collected at electrodes.
H2O
Reduction: (1/2) O2 + CO2 + 2e− → CO32−
Basically the PEMFC is comprised of
MCFCs are currently employed for natural
bipolar plates and membrane electrode
gas and coal based power plants in electrical
assembly (MEA). The MEA is composed of
utility, industrial and military applications.
dispersed catalyst layer, carbon cloth or gas
The
diffusion
advantages
and
disadvantages
of
layer
and
the
membrane.
MCFCs are closely related to its high
Membrane is to transport protons from
operating temperature. MCFC may be
anode to cathode and block the passage of
directly fuelled with hydrogen, carbon
electron and reactants. Gas diffusion layer is
monoxide, natural gas and propane. They do
to access the fuel uniformly. Electrons at
not require noble metal catalysts for electro
anode pass through the external circuit and
chemical oxidation and reduction. They also
generate electricity.
do
not
require
any
infrastructure
development for installation; however, long
time is needed to reach to the operating
temperature and generating power.
PROTON EXCHANGE MEMBRANE
FUEL CELL (PEMFC)
In PEMFCs, the hydrogen is activated by
catalyst to form proton ion and eject electron
at the anode. The proton passes through the
membrane while electrons are forced to flow
to
the
external
circuit
and
generate
electricity. The electron then flows back to
the cathode and interact with oxygen and
proton ion to form water. The chemical
reactions occurring at each electrode
Anode: H2 (g) → 2H+ + 2e−
PEMFCs are low temperature fuel cells with
operating temperature between 60 and
100◦C. They are light weight compact
systems with rapid start-up process. The
sealing of electrodes in PEMFCs is easier
than other types of fuel cells because of
solidity of the electrolyte. In addition, they
have longer life time and cheaper to
manufacture. The total cost of car with the
FEMFC system is 500–600$/kW which is
10 folded compare with cars using Internal
Combustion Engine (IEC). Total cost of the
PEMFCs includes the costs of assembly
DIRECT METHANOL FUEL CELL
process, bipolar plate, platinum electrode,
(DMFC)
membrane and peripherals. From efficiency
point of view, the higher the working
Direct methanol fuel cell (DMFC) is
temperature the higher efficiency can be
promoted type of the PEMFCs. It is a
gained. This is due to the higher reaction
suitable source of power for portable energy
rate. Nevertheless, working temperature
purposes due to low temperature operation,
above 100◦C will vaporize the water causing
long life time and rapid refueling system
dehydration to the membrane which leads to
characteristics. In addition, they do not need
the reduction in the proton conductivity of
to be recharged and are addressed as clean
the membrane. Electrical efficiency of
renewable energy source. Energy source of
PEMFCs is between 40 and 50% and the
the DMFC systems is methanol. At anode,
output power can be as high as 250kW.
methanol is reformed in to carbon dioxide
PEMFC systems are usually used in portable
(CO2) while at cathode steam or water is
and
However,
formed using oxygen available in the air.
PEMFCs,
The reactions are
stationary
among
applications.
applications
of
transportation seems to be the most suitable
since they provide continuous electrical
energy supply at high level of efficiency and
power density. They also require minimum
maintenance because there are no moving
DMFC systems are generally classified in to
parts in the power generating stacks of the
active and passive. Active DMFCs are high
fuel cells. Fuel cell vehicles are the most
efficient and reliable systems consisting
promising application of PEMFC systems.
of methanol feed pump, CO2 separator, fuel
The
of
cell stack, methanol sensor, circulation
technology development by people which
pump, pump drivers and controllers. Using
can significantly improve the acceptability
pump for water circulation can significantly
of such systems among communities. A
increase the efficiency of such systems.
reason
is
the
observability
report from McNicoletal states that a FCV
can
successfully
contend
against
conventional ICE vehicles. However, the
initial cost for FCV is higher than that for
ICE vehicles.
Active DMFCs are usually used in control
In addition, it provides high thermal and
applications for quantities such as flow rate,
chemical stability for proper performing of
concentration
the
DMFC. Flemion from Asahi Chemical and
passive DMFC systems, the methanol
Nafion from Dupont are the most common
pumping devices and external process for
per fluorinated ion-exchange polymers used
blowing air in to the cell are eliminated.
for DMFC. They have both mechanical
Hence, oxygen of ambient air is defused in
strength and high hydro phobicity of the
to the cathode via air breathing feature of the
sulphuric acids which is more prominent due
cell. Similarly, methanol is defused in to the
to the presence of the water. As a
anode from an integrated feed reservoir
consequence, water and methanol travel
driven by a concentration gradient between
across per fluorosulfonic acid membrane
the anode and the reservoir. Passive systems
which is a form of methanol cross over that
are cheap, simple and capable of substantial
has negative impact on its performance. The
reduction in parasitic power loss and system
PEM can be modified to overcome this
volume. Methanol is utilized in DMFCs
problem
inform of vapor or liquid. Vapor feed is
preparing composite membrane by the
preferable to liquid feed in term of cell
incorporation
voltage and power density. Methanol does
materials.
and
temperature.
In
in
2
ways:
sulfonation
of
in
organic
of
different
and
ceramic
not perform perfectly for mass transfer and
requires high localized cooling at anode.
Comparison
Furthermore, the extent of methanol cross
technologies
over from anode to cathode and gas release
at the electro catalyst surface leads to the
lower performance of liquid feed cells. On
the other hand, vapor feed cells have some
draw backs as well, such as dehydrating the
membrane,
less
life
time
and
high
temperature required for fuel vaporization.
Consequently, more complex and costly
reformer is needed. In addition, they are not
suitable for portable applications. Proton
Exchange Membrane (PEM) is considered
as the main part in DMFCs to provide low
penetrability and high proton conductivity.
fuel
cell
Applications of fuel cells depend on the type
of fuel cell to be used. With various types of
fuel cell technologies available, it is
necessary to clarify which technology is best
suited to a specific application. Fuel cells
can produce a wide range of power from 1
to 10 MW; hence they can be employed in
almost any application that needs power.
They can be used in small range power
devices and personal electronic equipment
such as mobile phones and personal
computers (PCs). Medium scale power
applications include fuel cell vehicles,
domestic appliances, military applications
and public transportation. Finally, in the
large range power applications (1–10MW),
Fuel cells are used in distributed power
systems and grid quality AC.
Operational Specifications of fuel cell technologies.
Comparisons of technical characteristics of fuel cell technologies.
APPLICATIONS
Fuel cells can be deployed in any
setting where a reliable source of base load,
on-site power is desired and, ideally, where
by-product heat can be effectively utilized.
They are also well-suited as alternatives to
batteries or diesel generators for strictly
back-up power applications, particularly in
remote areas (such as cellular phone
towers), and at critical facilities in urban
Because fuel cells can operate as a
areas with air quality issues. Current Fuel
continuous, baseload source of power
Cell Market There are currently several
(unlike
hundred large fuel cell installations in the
intermittent), these capital costs can be
United States. In 2010, the U.S. market grew
spread out over far more kilowatt-hours
by more than 50%. Globally, 30 to 50
(kWh)
megawatts (MW) of fuel cell capacity are
byproduct heat is captured and re-used. UTC
being installed annually with a projected 213
Power projects that its PureCell® 400 kW
MW of new installed capacity in 2013.
unit will be able to produce power at
Projects are getting larger, with the average
16¢/kWh (with 50% heat utilization), and at
stationary fuel cell installation growing to
14¢/kWh (with 100% heat utilization),
about 1 MW, up from 250 kW in 2005.
before any federal or state subsidies. The
Costs
cell
capital costs of fuel cells can also be
installations have dropped from about
transferred through third-party ownership, in
$600,000 per kW in the 1970s (when fuel
which
cells were developed for NASA) to about
intermediary owns the system, realizes the
$4,500 per kW today for the most widely
tax benefits and sells energy to the host
deployed technologies. This is higher than
facility under a fixed price contract.
Costs
for
stationary
fuel
solar
or
produced,
a
wind
which
especially when
manufacturer
or
are
the
financial
the capital costs for fossil-fuel based
distributed
generation
such
as
diesel
generators and gas turbines. But it is lower
than the capital costs of other distributed
clean energy technologies such as solar
photovoltaics. The U.S. Department of
Energy’s goal is to reduce this cost to about
$400 per installed kW by 2020 for solid
oxide fuel cell technology. It has formed the
Solid State Energy Conversion Alliance
(SECA), a government-industry partnership
BENEFITS OF FUEL CELLS
Stationary
fuel
cells
have
considerable benefits both to the facility
where they are installed and to the public at
large. These benefits will multiply as the
costs of fuel cells continue to decline
relative to grid power and the number of
installations increases.
USER BENEFITS
to achieve that goal. Like renewable energy
technologies, fuel cells are eligible for the
Reliability
30% federal Investment Tax Credit and for
direct financial subsidies, in some states,
Fuel cells are well suited for primary power
lowering their capital costs considerably.
applications, providing both an extremely
any local concerns over on-site hydrogen
storage.
Remote operation
reliable and
Fuel cells can be operated and
high-quality source of on-site power. This
monitored remotely. This is important for
reliability makes them ideal for public safety
fuel cells installed as backup power in
facilities
such
remote
centers,
police
as
and
emergency
fire
dispatch
stations
and
locations
such
as
telecommunications towers.
hospitals. For private facilities such as
computer server farms, data centers and
laboratories where even momentary losses
of power or voltage changes can disrupt
computers and sensitive equipment, fuel
cells deliver the sustained power quality
needed, with grid power acting as a backup.
Even noncritical facilities such as office
buildings, retail stores and hotels can benefit
Base load Clean Energy
Many businesses and public facilities
are installing solar photo voltaics as a way
of providing on-site clean energy. Fuel cells’
high efficiency and ability to produce
constant
power
makes
them
a
good
complement to solar.
from a grid-independent source of power
that can also displace other fuels for heating,
cooling and refrigeration.
Energy Cost Hedge
Siting
The installation of fuel cells can
While fuel cells have some local
siting challenges, in general they are easy to
site relative to other distributed generation
technologies because they can operate
emission-free, are quiet and compact. In
some states such as California, they are
completely
exempt
from
permitting
insulate businesses from unpredictable and
rising electricity costs. While fuel cells still
require hydrogen or natural gas as an input,
these costs might rise less quickly than
electricity, particularly in the event of state,
regional, or federal carbon legislation.
PUBLIC BENEFITS
requirements. Fuel cell technologies that
directly utilize natural gas (or biogas) avoid
Environmental
Stationary
fuel
cells
result
in
also defer the need to build both additional
dramatically reduced onsite air pollution
generation and distribution system upgrades.
relative to back-up diesel generators. They
can also result in reduced emissions relative
Public Safety and Security
to grid power depending on the source of
generation that is displaced. This is due to
the use of natural gas or biogas as the source
of hydrogen, the high conversion efficiency
of fuel cells, and the absence of particulate
emissions.
Fuel
cells
are
driven
by
electrochemistry, not combustion. As a
result, fuel cells emit only trace amounts of
NOx. Because fuel cells are intolerant of
sulfur,
the
fuels
used
have
to
When power blackouts occur, the
need to maintain critical public facilities and
services ranging from police and fire
dispatch to hospitals to water pumping and
wastewater treatment is essential. Fuel cells
provide a reliable way to ensure that these
facilities stay up and running.
CONCLUSIONS
be
desulfurized, and thus fuel cells emit no
Fuel
cells
are
coming
into
SOx. If the direct fuel input is hydrogen,
widespread commercial use for stationary
then only water vapor is generated in the
applications, and their combination of
exhaust. Because of the high electrical
reliability, efficiency, and low environmental
efficiency of fuel cells, the amount of CO2
impact
emitted per kWh of electricity generated is
distributed generation technology for a
lower than from conventional fossil fuel
range of applications. As the technology
generation. Avoided emissions are further
improves and costs decline, more businesses
increased when the facility is configured to
and public institutions should turn to fuel
utilize the waste heat from the fuel cell.
cells as a source of both primary and backup
make
them
an
outstanding
power. However, as with other clean energy
Avoided Generation and Transmission
technologies, states play an important role in
Costs
accelerating their adoption through both
Like other distributed generation
technologies, fuel cells displace utility
purchases of wholesale electricity on the
margin and during peak demand periods.
The cumulative effect of fuel cells with
other distributed generation resources can
public policy and financial support. Policies
such as including fuel cells as eligible
resources
in
state
renewable
portfolio
standards, encouraging or requiring the use
of fuel cells in critical public facilities, and
adopting uniform siting guidelines are
important steps. In addition, providing
financial incentives through state clean
energy funds can help businesses overcome
the first cost hurdles of installing fuel cells.
These policy recommendations are reviewed
in greater depth in an accompanying briefing
paper, “Advancing Stationary Fuel Cells
through State Policies.”
REFERENCES
Fundamentals of Renewable Energy
Processes, First Edition By Aldo V. da Rosa
Fundamentals of Renewable Energy
Processes, Second Edition By Aldo V. da
Rosa
Fundamentals of Renewable Energy
Processes, Third Edition By Aldo V. da Rosa
http://en.wikipedia.org/wiki/Fuel_cell
http://www.yourarticlelibrary.com/fuel/fuelcell-advantages-and-disadvantage-of-fuelcell/12358/
http://www.fuelcelltoday.com/technologies/s
ofc
https://www.clarkson.edu/highschool/k12/pr
oject/documents/energysystems/LP_3fuelcel
l.pdf
http://www.academia.edu/2169263/Compara
tive_study_of_different_fuel_cell_technolog
ies
http://www.cesa.org/assets/2011Files/Hydrogen-and-Fuel-Cells/CESA-FuelCells-Brifing-Papers-for-StatePolicymakers-Aug2011.pdf