Renewable Energy Sources -Fuel Cells

1. Review of Conventional and
Non Conventional Energy
Sources

3. Types of Energy sources
1. Conventional energy sources (or) Non-renewable energy sources
2. Non-Conventional energy sources (or) Renewable energy sources
• Generally, non-renewable energy sources come out of the
ground as liquids, gases and solids.
Examples: The conventional (or) Non-renewable energy
sources are Oil, Coal, Petroleum and natural
gas, Nuclear energy
(1) Conventional energy (or) Non-renewable energy
Conventional (or) Non-renewable energy sources are those, which
cannot be replaced continuously.

4. We can obtain renewable energy from the sun, from the water,
from the wind, from crop residues and waste
The types of Non-conventional (or) Renewable energies are
Solar energy (Unit-2) Tidal energy (Unit-4)
Wind energy (Unit-3) Hydro energy
Biomass energ(Unit-5) Biofuels (Unit-5)
Geothermal energy Wave Power (Unit-4)
Non-Conventional energy (or) Renewable
energy
Renewable energy is a source of energy that can never be
exhausted and can be replaced continuously.

5. PH 0101 Unit-5 Lecture -1 5

6. PH 0101 Unit-5 Lecture -1 6

7. Conventional Sources of Energy Non-conventional sources of energy
These sources of energy are also known
as a non-renewable source of energy
These sources of energy are also known
as a renewable source of energy
They find both commercial and
industrial purposes
They are mainly used for household
purposes
These can be considered to be one of
the reasons for the cause of pollution
These are not responsible for the cause
of pollution
Coal, fossil fuels are two examples
Wind, solar energy and Biomass two
examples
Difference Between Conventional and
Non-conventional Sources of Energy

8. Need for Non conventional Energy Sources
1. The growing consumption of energy has resulted in the
country becoming increasingly dependent on fossil fuels such
as coal, oil and gas.
2. Rising prices of oil and gas and their potential shortages have
raised uncertainties about the security of energy supply in future,
which has serious repercussions on the growth of the national
economy.
3. Increasing use of fossil fuels also causes serious environmental
problems.
4. Hence, there is a primary need to use renewable energy
sources like solar, wind, tidal, biomass and energy from waste
material. They are called non-conventional sources of energy.

9. Advantages of Conventional Sources of Energy:
1. The efficiency of the energy sources is high. Because from 1gm of uranium
we get 1 MW energy, from 1-tonne coal we get 2460 kWh energy. Solar panels
typically have between 15% and 20% efficiency, while coal has an efficiency
of up to 40% and natural gas reaches up to 60%.
2. The production expenses are low. According to government data of August
2021, the price of Uranium is $50/lb.
3. The raw materials of conventional Sources of Energy are easy to transport.
Raw materials such as coal, petroleum, natural gas can be transported easily
through trains or ships from one place to another.
4. Generally it doesn’t need any specific place for installation. The government
can easily set up a conventional plant according to their requirements. Such as
if the government wants to install a thermal plant in Uttarakhand or in Jammu
they can easily install it.
5. Though it can generate energy instance, so there is no need to wait and it
produces much energy as the requirements.

10. Disadvantages of Conventional Sources of Energy
1. They are the main reason for the pollution. Because it is
released carbon monoxide from polluters into the atmosphere.
According to The International Energy Agency, only in 2018, India
emitted 2,299 million tonnes of carbon monoxide. This report
also said that India’s per capita emissions were about 40% of the
global average and contributed 7% to the global carbon dioxide
burden.
2. Generating radioactive waste. We all know about the
Fukushima Daiichi nuclear disaster which happened in 2011.
Recently Japanese government has decided to release
radioactively contaminated water into the ocean. But the
environmentalists warn that it should be harmful to ocean life.
3. High startup cost. According to the government estimate, the
cost may be about 50 to 70 crores INR for setting up a 10 MW
thermal power unit. Whereas to set up a nuclear power plant, it
is required ₹60,000 crores.

11. Advantages of Non-Conventional Sources of Energy
The non-conventional sources of energy have many advantages:
1. Renewable and less expensive: Most non-conventional resources are
cheaper and can be reused as compared to conventional sources.
2. Environment friendly: As it is reused, it reduces the CO2 emissions which
causes less pollution and harm to the environment also it is inexhaustible.
3. Requires less maintenance: Because of less maintenance it remains less
expensive and it also provides a sustainable environment to live in.
4. Long term and future benefits: It strengthen the countries’ energy security
and it is mostly imported free, it boosts the sustainability.

12. Disadvantages of Non-Conventional Sources of Energy
1. Inconsistent and Unreliable Supply: Geothermal plants deplete their
energy resources and it becomes unpredictable. In the case of solar
energy, the energy needed to be stored so that electricity can be
produced.
2. Certain risks: Windmill blades sometimes become harmful and start
harming various species like birds, bats and insects. Certain solar energy
creates extreme hot zones in the environment
3 . Radioactive waste: Nuclear energy generates radioactive waste from
radioactive materials.
4. Harms natural habitats: Harnessing tidal energy destroys natural habitats
and harms wild animals.

13. Q1.What is the importance of non-conventional sources of energy?
A:Non-conventional sources of energy are important as they are less harmful to nature
and they are renewable and available in abundance.
Q2.What is the largest non-conventional source of energy?
A: Solar energy is the largest non-conventional source of energy.
Q 3.What is Solar energy?
A:Solar energy is produced by sunlight. Cells are exposed to sunlight which produces
electricity . This energy is also used for cooking.
Q 4.What are the advantages of non-conventional sources of energy?
A:Non-conventional sources of energy are easy to operate, less expensive, and less
harmful to the environment.
Q5.What are the disadvantages of non-conventional sources of energy?
A: In non-conventional sources of energy, sometimes affects the environment and there
is a certain risk for the small species of their survival. It is also very unpredictable and to
produce electricity a lot of energy or power is needed to be stored.

14. FUEL CELLS

18. A fuel cell is an electrochemical device that
produces electricity without combustion by
combining hydrogen and oxygen to produce water
and heat.
Fuel cell

19. Discovered German Scientist G H Shoenbein
First developed by William Grove
In 1839, Grove was experimenting on electrolysis
(the process by which water is split into hydrogen
and oxygen by an electric current), when he
observed that combining the same elements
could also produce an electric current

20. 1930s -1950s Francis Thomas Bacon, a British
scientist, worked on developing alkaline fuel
cells.
He demonstrated a working stack in 1958.
The technology was licensed to Pratt and
Whitney where it was utilized for the Apollo
spacecraft fuel cells.

21. Advantages over conventional energy sources
They produce zero or very low emissions, especially Green
House Gases (GHGs) depending on the fuel used.
Have few moving parts and thus require minimal
maintenance, reducing life cycle costs of energy production.
Modular in design, offering flexibility in size and
efficiencies in manufacturing
Can be utilized for combined heat and power purposes,
further increasing the efficiency of energy production

22. Working Principle
A fuel cell is a device that uses hydrogen (or hydrogen-rich
fuel) and oxygen to create electricity by an electrochemical
process.
A single fuel cell consists of an electrolyte sandwiched
between two thin electrodes (a porous anode and cathode)
Hydrogen, or a hydrogen-rich fuel, is fed to the anode where
a catalyst separates hydrogen's negatively charged electrons
from positively charged ions (protons)
At the cathode, oxygen combines with electrons and, in
some cases, with species such as protons or water, resulting
in water or hydroxide ions, respectively

23. The electrons from the anode side of the cell cannot pass
through the membrane to the positively charged cathode;
they must travel around it via an electrical circuit to reach
the other side of the cell. This movement of electrons is an
electrical current.
The amount of power produced by a fuel cell depends upon
several factors, such as fuel cell type, cell size, the
temperature at which it operates, and the pressure at which
the gases are supplied to the cell
Still, a single fuel cell produces enough electricity for only
the smallest applications. Therefore, individual fuel cells are
typically combined in series into a fuel cell stack. A typical
fuel cell stack may consist of hundreds of fuel cells.

24. Fuel cells are classified primarily by the kind of electrolyte
they employ. This determines the kind of chemical reactions
that take place in the cell, the kind of catalysts required, the
temperature range in which the cell operates, the fuel
required, and other factors.
There are several types of fuel cells currently under
development, each with its own advantages, limitations,
and potential applications.

25. Classification of Fuel Cells
Based on the type of Electrolyte
1. Alkaline Fuel cell (AFC)
2. Phosphoric Acid Fuel cell (PAFC)
3. Polymer Electrolytic Membrane Fuel Cell (PEMFC)
Solid Polymer Fuel Cell (SPFC) and
Proton Exchange Membrane Fuel cell (PEMFC)
4. Molten Carbonate Fuel Cell (MCFC)
5. Solid Oxide Fuel Cell (SOFC)
Based on Types of Fuel and oxidant
1. Hydrogen (pure)-Oxygen (pure) fuel cell
2. Hydrogen rich gas-air fuel cell
3. Ammonia –air fuel cell
4. Synthesis gas- air fuel cell
5. Hydro carbon (gas)- air fuel cell
Based on operating temperature

26. Alkaline Fuel Cells (AFC)
The alkaline fuel cell uses an alkaline electrolyte such as 40% aqueous
potassium hydroxide. In alkaline fuel cells, negative ions travel
through the electrolyte to the anode where they combine with
hydrogen to generate water and electrons.
It was originally used by NASA on space missions. NASA space shuttles
use Alkaline Fuel Cells. Alkaline fuel cells (AFCs) were one of the first
fuel cell technologies developed, and they were the first type widely
used in the U.S. space program to produce electrical energy and water
onboard spacecraft. These fuel cells use a solution of potassium
hydroxide in water as the electrolyte and can use a variety of non-
precious metals as a catalyst at the anode and cathode. High-
temperature AFCs operate at temperatures between 100ºC and 250ºC
(212ºF and 482ºF). However, more-recent AFC designs operate at
lower temperatures of roughly 23ºC to 70ºC (74ºF to 158ºF).

27. AFCs are high-performance fuel cells due to the rate at which chemical
reactions take place in the cell. They are also very efficient, reaching
efficiencies of 60 percent in space applications.
The disadvantage of this fuel cell type is that it is easily poisoned by
carbon dioxide (CO2). In fact, even the small amount of CO2 in the air
can affect the cell's operation, making it necessary to purify both the
hydrogen and oxygen used in the cell. CO2 can combine with KOH to
form potasium carbonate which will increase the resistance.
This purification process is costly. Susceptibility to poisoning also affects
the cell's lifetime (the amount of time before it must be replaced),
further adding to cost.
Cost is less of a factor for remote locations such as space or under the
sea. However, to effectively compete in most mainstream commercial
markets, these fuel cells will have to become more cost effective. AFC
stacks have been shown to maintain sufficiently stable operation for
more than 8,000 operating hours..

28. Anode Reaction: 2H2 + 4OH- »» 4H2O + 4e-
Cathode Reaction: O2 + 2H2O + 4e- »» 4OH-

29. Molten Carbonate Fuel Cells (MCFC):
The molten carbonate fuel cell uses a molten carbonate salt as the
electrolyte. It has the potential to be fuelled with coal- derived fuel
gases, methane or natural gas. These fuel cells can work at up to
60% efficiency
In molten carbonate fuel cells, negative ions travel through the
electrolyte to the anode where they combine with hydrogen to
generate water and electrons.
Molten carbonate fuel cells (MCFCs) are currently being developed for
natural gas and coal-based power plants for electrical utility, industrial,
and military applications. MCFCs are high-temperature fuel cells that
use an electrolyte composed of a molten carbonate salt mixture
suspended in a porous, chemically inert ceramic lithium aluminum
oxide (LiAlO2) matrix. Since they operate at extremely high
temperatures of 650ºC and above, nonprecious metals can be used as
catalysts at the anode and cathode, reducing costs.

30. Unlike alkaline, phosphoric acid, and polymer electrolyte membrane
fuel cells, MCFCs don't require an external reformer to convert more
energy-dense fuels to hydrogen. Due to the high temperatures at which
they operate, these fuels are converted to hydrogen within the fuel cell
itself by a process called internal reforming, which also reduces cost.
Although they are more resistant to impurities than other fuel cell
types, scientists are looking for ways to make MCFCs resistant enough to
impurities from coal, such as sulfur and particulates.
The primary disadvantage of current MCFC technology is durability. The
high temperatures at which these cells operate and the corrosive
electrolyte used accelerate component breakdown and corrosion,
decreasing cell life.
Scientists are currently exploring corrosion-resistant materials for
components as well as fuel cell designs that increase cell life without
decreasing performance.

31. Anode Reaction: CO3
-2 + H2 → H2O + CO2 + 2e-
Cathode Reaction: CO2 + ½O2 + 2e- → CO3
-2
Overall Cell Reaction: H2 + ½O2 → H2O

32. Phosphoric Acid Fuel Cells (PAFC):
A phosphoric acid fuel cell (PAFC) consists of an anode and a cathode
made of a finely dispersed platinum catalyst on carbon and a silicon
carbide structure that holds the phosphoric acid electrolyte.
In phosphoric acid fuel cells, protons move through the electrolyte to the
cathode to combine with oxygen and electrons, producing water and
heat.
This is the most commercially developed type of fuel
cell and is being used to power many commercial
premises

33. Phosphoric acid fuel cells use liquid phosphoric acid as an electrolyte—
the acid is contained in a Teflon-bonded silicon carbide matrix—and
porous carbon electrodes containing a platinum catalyst.
The phosphoric acid fuel cell (PAFC) is considered the "first generation"
of modern fuel cells. It is one of the most mature cell types and the first
to be used commercially, with over 200 units currently in use.
This type of fuel cell is typically used for stationary power generation,
but some PAFCs have been used to power large vehicles such as city
buses
PAFCs are more tolerant of impurities

34. They are 85 percent efficient when used for the co-generation of
electricity and heat, but less efficient at generating electricity alone
(37 to 42 percent).
PAFCs are also less powerful than other fuel cells, given the same
weight and volume. As a result, these fuel cells are typically large
and heavy. PAFCs are also expensive.
Like PEM fuel cells, PAFCs require an expensive platinum catalyst,
which raises the cost of the fuel cell.

35. Polymer electrolyte membrane (PEM) fuel cells (PEMFC)
In polymer electrolyte membrane (PEM) fuel cells, protons move
through the electrolyte to the cathode to combine with oxygen and
electrons, producing water and heat.
Polymer electrolyte membrane (PEM) fuel cell uses a polymeric membrane
as the electrolyte, with platinum electrodes.
These cells operate at relatively low temperatures
These cells are the best candidates for cars, for buildings and smaller
applications. Polymer electrolyte membrane (PEM) fuel cells—also called
proton exchange membrane fuel cells—deliver high power density and offer
the advantages of low weight and volume, compared to other fuel cells. PEM
fuel cells use a solid polymer as an electrolyte and porous carbon electrodes
containing a platinum catalyst.
They only hydrogen, oxygen from the air, and water to operate and do not
require corrosive fluids like some fuel cells. They are typically fueled with
pure hydrogen supplied from storage tanks or onboard reformers

36. Polymer electrolyte membrane fuel cells
operate at relatively low
temperatures, around 80°C (176°F).
Low temperature operation allows them
to start quickly (less warm-up time) and results
in less wear on system
components, resulting in better durability.
However, it requires that a noblemetal
catalyst (typically platinum) be used to
separate the hydrogen's electrons
and protons, adding to system cost.
The platinum catalyst is also extremely
sensitive to CO poisoning, making it necessary
to employ an additional
reactor to reduce CO in the fuel gas if the
hydrogen is derived from an alcohol
or hydrocarbon fuel. This also adds cost.
Developers are currently exploring
platinum/ruthenium catalysts that are more
resistant to CO.

37. Solid Oxide Fuel Cells (SOFC)
Work at higher temperatures
They use a solid ceramic electrolyte, such as
zirconium oxide stabilised with yttrium oxide,
instead of a liquid and operate at 800 to 1,000°C.
In solid oxide fuel cells, negative ions travel
through the electrolyte to the anode where they
combine with hydrogen to generate water and
electrons.
Efficiencies of around 60 per cent and are
expected to be used for generating electricity
and heat in industry and potentially for providing
auxiliary power in vehicles.
Since the electrolyte is a solid, the cells do not
have to be constructed in the plate-like
configuration typical of other fuel cell
types.
Anode Reaction: 2H2 + 2O–2 →
2H2O + 4e–
Cathode Reaction: O2 + 4e– →
2O–2
Overall Cell Reaction: 2H2 + O2 →
2H2O

38. High temperature operation removes the need for precious-metal
catalyst, thereby reducing cost.
They are not poisoned by carbon monoxide (CO), which can even be
used as fuel.
Sulphur resistant
This allows SOFCs to use gases made from coal.
Scientists are currently exploring the potential for developing lower-
temperature SOFCs operating at or below 800ºC that have fewer
durability problems and cost less.

39. Regenerative Fuel Cells (RFC):
This class of fuel cells produces electricity from
hydrogen and oxygen, but can be reversed and
powered with electricity to produce hydrogen and
oxygen; effectively storing energy or electricity

41. Basic energy conversion of a fuel cell can be described as:
Chemical energy of fuel = Electrical energy + Heat energy
The input energy is that produced during
reactions at the electrodes.

42. Performance
One measure of the energy conversion efficiency of a
fuel cell is the ratio of the actual voltage at a given
current density to the maximum voltage obtained under
no load (open circuit) conditions.
Ƞ = On load voltage / theoretical open circuit voltage

43. Thermodynamic Analysis: 1st Law
It is usually formulated by stating that the change in the
internal energy (∆H) of a closed system is equal to the
amount of heat supplied (Q) to the system, minus the
amount of work (W) performed by the system on its
surroundings.

44. Electrical work is, in general, described by the relation: W = EIΔt
where E is the cell voltage and I is the current
In a fuel cell reaction, electrons are transferred from the anode to the
cathode, generating a current.
The amount of electricity (IΔt) transferred when the reaction occurs is
given by NF, where
N = number of electrons transferred
F = Faraday’s constant = 96,493 coloumbs
So the electrical work can be calculated as: W = NFE (Work done on
the surrounding)
Defining the work term
The First Law then becomes: ΔH = Q - NFE

45. Consider the fuel cell to be ideal for now, meaning that it is reversible and thus
behaves as a perfect electrochemical apparatus :
“ If no changes take place in the cell except during the passage of
current, and all changes which accompany the current can be reversed by reversing
the current, the cell may be called a perfect elctrochemical
apparatus.”
Heat transferred during a reversible process was expressed as:
Q = T ΔS (1)
Combining the First and Second Law analysis, we get
T = absolute temperature, ΔS = change in entropy
ΔH = TΔS – NFE (2)
NFE = - (ΔH - TΔS ) (3)
Gibbs Free Energy is given by G= H – TS
Or ΔG = ΔH-(T ΔS-S ΔT)
ΔG = ΔH-T ΔS (4)
As there is no change in temperature ΔT = 0
Eqn (2) becomes NFE = - Δ G)
Thermodynamic Analysis: 2nd Law
Max efficiency = NFE/ΔH

46. Physical Interpretation of dG = dH - TdS
dH represents the total energy of the system.
TdS represents the “unavailable” energy (that which cannot
be converted to useful work).
Therefore G represents the “free” energy or the energy
available to do useful work.

47. Fuel Cell Efficiency
Since fuel cells use materials that are typically burnt to release their
energy, the fuel cell efficiency is described as the ratio of the
electrical energy produced to the heat that is produced by burning
the fuel.
From the basic definition of efficiency: η = W / Qin
Hydrogen fuel cell:
Oxidation half reaction 2H2 4H+ + 4e-
Reduction half reaction O2 + 4H+ + 4e- 2H2O
Energy formation (KJ/mole)
-ΔHo = 286 -ΔGo = 237
The maximum efficiency of the fuel cell would be 83%.

48. Classification of Losses in an Actual Fuel Cell
Activation Losses: These losses are caused by the slowness of the reaction
taking place on the surface of the electrodes. A proportion of the voltage
generated is lost in driving the chemical reaction that transfers the electrons.
Ohmic Losses: The voltage drop due to the resistance to the flow of
electrons
through the material of the electrodes. This loss varies linearly with current
density.
Concentration Losses: Losses that result from the change in concentration of
the reactants at the surface of the electrodes as the fuel is used.
Fuel Crossover Losses: Losses that result from the waste of fuel passing
through the electrolyte and electron conduction through the electrolyte.
This loss is typically small, but can be more important in low temperature
cells.

49. Applications of 0D, 1D, 2D and 3D NSMs
The main active components are fuel electrode (anode), oxidant
electrode (cathode). The proton conducting solid membrane used
as electrolyte, is sandwiched between the anode and cathode
electrodes
Although the technology of such fuel cells was developed to an
extent, some problems remain unclear and only their solution can
result in wide-scale commercialization of fuel cells, especially as
the efficient current sources for portable devices. The most
important problem is the development of efficient catalysts,
which would provide the long-term operation of fuel cells without
sacrificing their characteristics.

50. A hydrogen fuelled proton exchange
membrane fuel cell, for example,
uses hydrogen gas (H2) and oxygen (O2) to
produce electricity and water (H2O);
A regenerative hydrogen fuel cell uses
electricity and water to produce hydrogen
and oxygen.
Regenerative fuel cell

52. When the fuel cell is operated in regenerative mode, the anode for the
electricity production mode (fuel cell mode) becomes the cathode in the
hydrogen generation mode (reverse fuel cell mode), and vice versa.
When an external voltage is applied, water at the anode side will undergo
electrolysis to form oxygen and protons; protons will be transported
through the solid electrolyte to the cathode where they can be reduced
to form hydrogen.
In this reverse mode, the polarity of the cell is opposite to that for the
fuel cell mode. The following reactions describe the chemical process in
the hydrogen generation mode:
At cathode: H2O + 2e− → H2 + O2−
At anode: O2− → 1/2O2 + 2e−
Overall: H2O → 1/2O2 + H2

57. RFCs are used in applications
1. where relatively large amounts of electricity need to
be stored, such as energy storage for remote off-grid
power sources,
2. Emergency or backup power generation,
3. zero-emission vehicles,
4. Hybrid energy storage/propulsion systems for
underwater vehicles,
5.Spacecraft, and high-altitude long-endurance solar
rechargeable aircraft.

58. Advantages and Disadvantages of a Fuel Cell:
Advantages :
1. The electrode materials in a Fuel Cell are not changed during chemical
reaction so a Fuel Cell does not requires recharging, they can be used as a
continuous generator as long as the fuel and oxidizing agent are supplied.
2. Fuel cells does not have any moving parts; so, unlike normal generators they
does not produce sound , requires very little maintenance and produces no
gasses or fumes.
3. Fuel cell’s efficiency and cost per KW of power is independent of their size; so,
they also offer a design flexibility and a room for further research and
development.
Disadvantages :
1. Initial design and manufacturing cost of fuel cell is very high.
2. They produce small voltages .
3. Fuel cells service life is not much as compared to other cells.

61. Polarization
In reality, the cell achieves its highest output voltage only at open circuit
conditions and voltage drops off with increasing current drawn, similar as any
voltage source with internal resistance. In fuel cell terminology, it is known as
polarization and can be represented by a polarization curve as shown in Fig.

62. The polarization curve characterizes the cell voltage as
a function of the current.
The current, in turn, depends on the size of the
external electrical load that the fuel cell powers.
The polarization curve also shows the electrochemical
efficiency of the fuel cell at any operating current.
The efficiency is often defined as the ratio of the actual
cell voltage over the theoretical maximum voltage.
Polarization is caused by chemical and physical factors associated
with various elements in the fuel cell, such as temperature,
pressure, gas composition, and fuel properties and reactant
utilization. These factors limit the reaction processes.

63. There are three main types of polarizations
1. Activation polarization,
2.Ohmic (or resistance) polarization and
3. Concentration polarization.
Fuel cells have the best performance in the
ohmic polarization region.

64. Low emission, when using hydrogen, the emission of fuel cell
based DG is almost zero.
No moving parts apart from the air and fuel compressors.
Therefore, it is more reliable, less noisy and low vibration.
It also has lower maintenance cost and longer operating life
compared to an equivalent coal-fired power plant or an internal
combustion engine.
Modularity, scalability and quick installation.
Fuel cells are manufactured as standard size units and can be
easily combined to meet any amount of power demand without
having to redesign and reconstruct the whole plant.
High energy conversion efficiency, on the order of 17% to
33% higher than other fossil fuel based DG options
Advantages of Fuel Cells

65. Good opportunities for cogeneration.
In addition to electrical power, medium to high temperature fuel cells,
such as PAFC, MCFC, and SOFC, will also generate pure hot water and
medium grade heat, both of which can potentially be used for domestic or
industrial applications. This is known as combined heat and power (CHP)
applications that could further increase the overall system efficiency.
Fuel cells are particularly well suited to distributed power generation
applications because of the above characteristics.

66. Fuel cells Drawbacks
High initial cost. Even though the cost of fuel cell systems has been
dramatically reduced since their first application in space industries,
However they still cost much more than other competing DG
technologies. This is the major barrier for fuel cells to succeed in the
already competitive market.
Complex support and control systems. The complexity of fuel cell
systems increases significantly when the fuel cells operate in conjunction
with an on-board reformer.
Fuel sensitivity. Many fuel cells are more sensitive to impurities in the
fuel, such as PEMFC and PAFC, than reciprocation or turbine engines.
Unproven track record. Since fuel cells do not have a long history of
commercial usage, therefore they are often considered risky from a
commercial application point of view.