Analysis of Fuel Cell Electric Vehicles (FCEVs) - Technical Report

This report provides a comprehensive overview of fuel cell electric vehicles (FCEVs), highlighting their advantages over traditional combustion engine vehicles and battery electric vehicles. It begins with an executive summary, followed by an introduction that emphasizes the growing importance of sustainable transportation and the role of FCEVs in reducing emissions. The report then delves into the operational principles of fuel cells, explaining how they convert hydrogen into electricity. It describes the components and working mechanisms, including the role of electrolytes, catalysts, and the reactions that occur at the anode and cathode. Different types of fuel cells, such as molten carbonate (MCFC) and solid oxide (SOFC), are also discussed, including their operational characteristics, reactions, and applications. Overall, the report aims to provide a detailed technical analysis of FCEVs, their underlying technology, and their potential to transform the automotive industry.

Executive Summary
The fuel cell electric vehicles which are often called FCEVs are a bit similar to battery electric
vehicles (BEVs) in terms of components like electric motors and power controllers or inverters.
But, the major difference is the main energy source. BEVs use the stored energy in the battery
whereas FCEVs use fuel cells as their energy source and it's very much more efficient than
batteries in various ways. The notable advantages in fuel cells are that they are very light weight
and compact which can produce the electricity if there is continuous supply of fuel. FCEV is
suitable for medium–large and long-range vehicles unlike BEVs. The principle involved in
FCEVs is that they use the low temperature fuel cells which generate electricity from hydrogen.
This energy can be used to drive vehicles or can also be stored in energy storage devices like
batteries and ultracapacitors. Low-temperature proton exchange membrane fuel cells (PEMFC)
is the best way to afford the high-energy densities and fast start-up times required for automotive
applications for low-carbon technologies. PEMFCs , which are fuelled by hydrogen, are capable
of generating electricity with the only local by-products which are water and heat. Since fuel
cells are completely reliant on chemical reactions to generate electricity which therefore results
in zero pollution due to absence of fuel combustion and produces much less heat than an ICE.
The by- product of a hydrogen fuel cell is hot water vapour. Fuel cells have the potential for high
reliability and low manufacturing cost because of absence of complex moving parts and irregular
shapes. Although FCEVs possess many limitations along with their significant advantages.
Introduction
Transportation is nowadays categorized as a necessity, and has over the last few years, seen a
conversion from focus on the type of fuel used to the various modes and milieus of mobility.
Today, the automotive industry is going through rapid technological changes of several parts,

especially the motor technologies. This sector remains one of the critical contributors to total
global emissions worldwide due to its high dependency on fossil fuels as its primary source of
energy. Pressure is rising on the automotive industry and it is felt through consumer demand for
higher fuel efficiencies in addition to regulations which either require low emissions or in some
cases, no emissions at all. This pressure that comes from environmental concerns along with the
rising fuel prices surrounding the traditional internal combustion engines have led to a push for
the development of more sustainable and eco-friendly vehicles. The industry has been
encouraged to reduce pollution and implement healthier environmental management (Walker, Di
Sisto & McBain, 2008). Hence, over the last few years, the implementation of green innovation
in this industry has been capturing the attention of researchers, manufacturers and decision-
makers. In this context, automobile companies and manufacturers have had to review their
production techniques and come up with new technologies and concepts to overcome the
challenges. Such activities involve taking into account environmental protection purposes within
several companies and departments in order to comply with regulations and enhance the
environmental performance while relying on inventive environmental management or green
technologies (Greeno & Robinson, 1992). Extensive research has been performed on ICE cars in
order to improve efficiency and reduce emissions; however, as long-term solution to eliminating
the dependency on oil and fuel consumption for transportation, advanced vehicles are being
developed that are based on other sources of energy, such as fuel cell electric vehicles (FCEVs)
and battery electric vehicles (BECs). Electric vehicles can broadly be defined as vehicles with
electric propulsion capability; such vehicles include HEV, BEV and FCV. The main focus in this
paper will be on FCEVs that use hydrogen as primary source of energy, Hydrogen is one of the
main sources of clean energy that is the most abundant element in the universe and has a very
high energy potential (Mehmet et al, 2017).
Hydrogen can be used for several production procedures as well as it can be used as an
alternative fuel of hydrogen which could represent a solution for green energy production. It can
be obtained from numerous sources and this diversity delivers a significant advantage, it is a
clean fuel. It is a source of energy that can be burned or converted to electrical energy by means
of a fuel cell; hence it can be adapted in internal combustion engines (ICEs) in which water
vapor along with other emissions are released from the exhaust or incorporated in electrical
vehicles as FCEVs with zero CO2 emissions. Recently, there has been a rapid progress in

generating green hydrogen which comes from different renewable energy sources. Although the
direct injection of hydrogen in the internal combustion engine has notable advantages, such as
high volumetric efficiency; there are some challenges that need to be overcome. Such challenges
include possible backfire and the increased formation of the NOx from the pre-ignition of the
hydrogen air mixture at high loading (A.G. Olabi, 2021).
The primary focus is on FCEVs as it is more convenient in terms of environmental aspects.
These systems, that depend on hydrogen as a fuel for generating electric energy in FC; and drive
the vehicle with electrical structure, show similarities to EVs in the technical maneuver. The
merits of FCEVs are many; some of the main advantages represent zero emission (only water),
silent drive, faster fueling, better fuel economy and efficiency, and easy maintenance.
Notwithstanding, FCEVs come with disadvantages too, such as limited range, storage and safety
challenges, expensive prices and less popularity and recognition (Bahattin et al, 2019).
Furthermore, rather than overflowing into the hands of consumers, FCEVs are trickling due to
the hydrogen infrastructure which is almost a decade behind BEV- recharging stakes; hence in
terms of research and development, FCEVs are falling behind BEVs. Nevertheless, this
technology can present a serious solution to the fossil fuel emission's problem, and with extended
exploration, can prove to be more efficient or convenient than BEVs. After all, BEVs mainly rely
on lithium-ion batteries which are complex products with a convoluted production chain that is
associated with environmental and economic risks. Hence, regulations concerning these batteries
are being forced with the need of recycling rechargeable batteries as it is induced by cleaner
production principles and better handling of the available resources. Therefore, working on
improving the field FCEVs is an attractive scheme. In this paper we aim to discuss..
Operation principles of fuel cells
A fuel cell is an electrochemical energy conversion device that uses hydrogen to generate
electricity. The principle feature of a fuel cell is that it can convert the chemical energy contained
in the fuel into electricity with higher efficiencies than traditional mechanical systems. The
electromechanical process doesn't include any thermal or mechanical processes and only requires
oxygen to trigger the reaction (A.G. Olabi, 2021). Since hydrogen gas contains a substantial

amount of chemical energy, when ignited, it will react with oxygen in the surroundings and
release its energy by means of explosion. The crucial characteristic of this reaction is that the
only waste product is water; hence there are no emissions of CO2 or other toxic gases. The
process delivers electricity in the form of low-voltage DC that provides direct work. Digging
deeper into the components and the workings on a fuel cell, the working principles resemble
those of a battery, both the fuel and the oxidant that are in gaseous phase form the anode and the
cathode and are channeled towards the electrolyte to feed the reaction. However, it should be
noted that unlike a battery, a fuel cell does not store electrical or chemical energy; the electrical
energy is directly extracted from a chemical reaction (Brown et al, 2021). In this case, the fuel
which is hydrogen is fed to the anode and the air is fed to the cathode. The electrolytes come in
several forms (liquid, gas, solid), operate at low or high temperatures and conduct electricity. For
automotive applications, the most common and relative fuel cells use a low temperature solid
electrolyte conducting hydrogen ions.
Oxygen is the most commonly used cathode material due to its abundance in air and high
reactivity while hydrogen is considered as a very effective fuel owing to high electrochemical
reactivity compared to other possible fuels, such as hydrocarbons or alcohols. In simple terms,
the process goes as follows: Hydrogen H2 that is located inside the anode has the tendency to
pass to the other side and react with oxygen; nonetheless, the electrolyte present in between does
not allow for the hydrogen to pass. The electrolyte only lets positively charged particles to pass
through it, hydrogen atoms consist of one proton and one electron hence they are neutral

particles and cannot pass through the electrolyte. This is why another material is located in
between which is the catalyst, the catalyst separates the electrons of the hydrogen atoms from
their protons which allows the presence of positively charged protons also known as H+ that can
actually move through the electrolyte to meet up with the oxygen. However, in order for the
reaction to take place, electrons are also needed and since only protons are present on the other
side, the electrons also have to be transported to the anode to formulate hydrogen. The
transferring of hydrogen electrons is actually simple, it happens using a wire that connects both
sides (the cathode and anode); the electrons and protons are now both present in the anode and
can formulate hydrogen that can react with oxygen. The reaction between oxygen and hydrogen
produces water and releases energy that can be converted to electricity for many usages. Note
that the use of catalyst is not always mandatory such as for high-temperature operating fuel cells.
The types of electrolytes used in these fuel cells can conduct negatively charged ions. However
for automotive applications, a fuel cell with a catalyst is usually required.
Fuel Cell Types:
Fuel cells usually differ in the type of electrolyte utilized, which actually affects the operational
temperature of the fuel cell; for instance, the so-called high-temperature fuel cells operate at
temperatures above 1100 F (600 C). Under such conditions, hydrocarbon fuels such as methane
directly reform into hydrogen and efficiently promote the electrochemical reactions without
requiring a catalyst. On the other hand, efficiency is inversely proportional to the reaction
temperature, meaning that an increase in temperature above certain thresholds greatly affects the
energy released (A.G. Olabi, 2021). Common high-temperature fuel cells are molten carbonate
(MCFC) and solid oxide (SOFC).
Molten carbonate fuel cell (MCFC):
The design of MCFC is complex due to the use of liquid electrolyte instead of solid; usually the
electrolyte consists of sodium (Na) and potassium (K) carbonate. Continuous CO2 should be
provided to meet the consumption of CO2 at the cathode. Hence, due to the production of CO2

during fossil fuel reforming, MCFCs are not a completely green technology. However, they are
promising due to their reliability and efficiency, especially when a cogeneration system is
implemented where an efficiency of 80% can be obtained. Current research is focused on
fabrication techniques and material development to reduce cost and improve efficiency. MCFC
cogeneration technology is widely used today. In this fuel cell type, carbonate salts are the
electrolyte. At high temperatures, the salt melts and conducts ions (CO2-3) from the cathode to the
anode. At the anode, the ions react with hydrogen to produce water, carbon dioxide and
electrons. The electrons return to the cathode through an external circuit providing electrical
power; at the cathode, the carbon dioxide from the anode reacts with oxygen from air to form
CO2-3 ions that replenish the electrolyte and conduct current through the fuel cell.
Reactions:
Anode Reaction: CO2-3 + H2 → 2H2O + CO2 + 2e-
Cathode Reaction: 1/2O2 + CO2 + 2e- → CO2-3
Overall Reaction: H2 + 1/2O2 → H2O
Solid oxide fuel cell (SOFC):
The solid oxide fuel cell uses solid oxide or ceramic electrolyte. These types of fuel cells operate
at high temperatures hence they do not require expensive platinum catalysts. Similar to MCFCS,
the high operation temperature allows for hydrocarbon fuels to be internally reformed with the
anode. This technology can deliver high combined heat and power efficiency, low emissions,
long-term stability and relatively low cost. However, there are some disadvantages associated
with SOFCs related to longer start-up times in addition to chemical and mechanical compatibility
issues due to the high operating temperature. Vulnerability to sulfur poisoning has been detected
in this technology; hence it is essential for sulfur to be removed before entering the cell using
adsorbent beds or other means. This fuel cell is usually made up from four layers, three of which
are ceramics which become ionically and electrically active at high temperatures. In the cathode,
oxygen is reduced into oxygen ions, these ions then diffuse through the solid electrolyte to the
anode where they can electrochemically oxidize the fuel. This reaction produces a water

byproduct in addition to two electrons; These electrons then flow through an external circuit
generating electricity and the cycle repeats.
Anode Reaction: O2- + H2 → H2O + 2e-
Cathode Reaction: 1/2O2 + 2e- → O2-
Overall Reaction: H2 + 1/2O2 → H2O
Fuel cells that operate below 480 ºF (250 ºC) are classified as low-temperature fuel cells. They
require catalysts which are usually made of expensive materials and an external source of
hydrogen. The lower temperature ranges allow for shorter start up times and do not cause much
material degradation while in use. These characteristics make the low-temperature fuel cells
attractive for automotive applications. Common low-temperature fuel cells are alkaline (AFC),
and proton exchange membrane (PEMPC).
Alkaline fuel cell (AFC):
Alkaline fuel cells are among the most efficient fuel cells, having a potential efficiency of around
70%. These cells consume hydrogen and pure oxygen, to produce water, heat, and electricity.
The anode and cathode are separated by a porous matrix saturated with an aqueous alkaline
solution, such as potassium hydroxide KOH (T.B. Ferriday, 2021). These cells usually operate
on pure oxygen or purified air since the use of carbon dioxide can cause the fuel cell to become
“poisoned” through the conversion of potassium hydroxide to potassium carbonate (K2CO3) by
the following reaction: CO2(g) + 2KOH(aq) → K2CO3(aq) + H2O(l). The chemicals reactions
occurring in the fuel cell are:
Anode Reaction: 2OH- + H2 → 2H2O + 2e-
Cathode Reaction: 1/2O2 + H2O + 2e- → 2OH-
Overall Reaction: H2 + 1/2O2 → H2O

Proton exchange membrane (PEMPC):
PEM fuel cells operate with an electrolyte conducting hydrogen ions (H+ ) from the anode to the
cathode. The electrolyte is made of a solid polymer in a form of acidified Teflon. These types of
fuel cells are the most commonly used for vehicle applications; since they afford high-energy
densities and fast start-up times required for automotive applications for low-carbon technologies
with the only local by-products being water and heat. A single fuel cell consists of an anode, a
cathode and membrane joined together to form a membrane electrode assembly (MEA) where
hydrogen and oxygen are combined (Billy. Wu, 2012). In the anode section, hydrogen molecules
are split into protons and electrons. The membrane separating the cathode and the anode is a
Nafion polymer that only allows for the conduction of hydrogen protons. Electrons are not able
to move through the membrane and thus must flow around an external circuit where electrical
work can be extracted. The chemicals reactions occurring in the fuel cell are:
Anode Reaction: H2 → 2H+ + 2e-
Cathode Reaction: 1/2O2 +2H+ + 2e- → H2O
Overall Reaction: H2 + 1/2O2 → H2O
For automotive applications, to achieve practical voltages, multiple MEAs and bipolar plates are
joined together to form an FC stack. The operating voltage is then the summation of the
individual cell voltages (Billy. Wu, 2012).
Classification of most prominent fuel cells
Fuel cell
type
Electrolyte
Conduction
Operation
temperature
Efficiency Advantages Disadvantages

Molten
Carbonate
(MCFC)
Carbonate
ions (CO2-3 )
600°C -
800°C
50% 1) High efficiency
2) Generate high-
grade waste heat
3) Fast reaction
kinetics
4) Catalyst not needed
1) High temperature
corrosion and
2) Electrolyte in
liquid form, which
introduces liquid
handling problems 3)
Long start-up time
Solid Oxide
(SOFC)
oxide ions
(O2-)
1000°C -
1200°C
60% 1) High efficiency
2) Generate high-
grade waste heat
3) Fast reaction
kinetics
4) Catalyst not needed
5) Wide variety of
modular
configurations
1) Moderate
intolerance to
sulphur, at 50 ppm 2)
Lack of practical
fabrication process 3)
Technology not
mature yet
Alkaline
(AFC)
hydroxyl ions
(OH-)
<100°C 60-70% 1) Fast start up times
2) Easy to operate 3)
Lower component cost
4) Platinum catalyst
not needed
5) Minimal corrosion
6) Low weight and
volume
1) Extremely
intolerant to CO2
(350 ppm max) and
CO
2) Requires pure
oxygen and pure
hydrogen.
3) Liquid electrolyte,
introducing complex
liquid handling
problems
Proton
Exchange
Membrane
(PEMPC)
hydrogen ions
(H+ )
60°C - 100°C 60% 1) Low temperature,
pressure and start up
time
2) Solid, dry, non-
corrosive electrolyte
3) High voltage,
current and power
density
4) Tolerant to CO2
content in air
5) Compact and solid
build with simple
mechanical design
1) Mid-tolerance to
CO (50ppm) and
sulphurs
2) Reactant gas needs
pre-humidification 3)
Requires platinum
catalyst 4) Fragile
and expensive PEM
Hydrogen and Fuel Cells vs. Other Gasoline and Electric Powered Vehicles
Hydrogen and fuel cells can surely represent the future of the automotive industry with the
elimination of fossil fuels. When comparing the hydrogen fuel cell with the other electric

powered vehicles, they pretty much offer the same thing. But, when comparing them in
parameters like emissions, cost, mileage and noise we definitely find significant advantages then
in conventional ICEs.
Schematic drawings of seven types of vehicles: (a) ICE vehicle; (b) battery electric vehicle; (c)
fuel cell electric vehicle, (d) series hybrid vehicle; (e) parallel hybrid vehicle; (f) series–parallel
hybrid vehicle and (g) complex hybrid vehicle, Fig 1.
Current status of low-carbon vehicle technologies and Comparisons:
During recent days many automotive manufacturers have shifted their research and development
efforts on high energy efficiency renewable energy vehicles by phasing off the reliance on fossil
fuel usage by conventional vehicles. We have many potential solutions in this domain which are
hybrid vehicles, bio fuel vehicles, BEV and FCEVs. But, we don’t have a clear picture currently
of which one could dominate in the future low carbon vehicle market. McKinsey predicts that
almost all the automotive companies have an equal interest in all four power – trains and scholars
state that all the current viable technologies are very potential and more likely to play a major
part in future sustainable transport systems.
Conventional ICE vehicles:
The Internal combustion engine (ICE) powered vehicles (Fig. 1a) are surely one of the greatest
milestones in the history of scientific inventions by humans ;the design has been perfected over

150 years and has become the most popular power plant for vehicles. This is mainly because of
the dominant advantages/features in the ICE; ICE runs on both petrol and diesel and also have a
superior power range when compared to the other vehicles like battery vehicles. This can be
explained by energy density in the petrol/diesel fuels in comparison with the batteries. This can
be represented by the Ragone plot, used for comparing the energy density of various storing
devices as well as energy devices like engines and fuel cells and so on. The ICE technology will
surely develop even further and dominate the automobile industry for many years, even speaking
about the current situation; people do prefer an ICE conventional vehicle as their first option
rather than hybrid vehicles. But, the hybrid vehicle’s ICE is very different from the conventional
ones. The engine in hybrid vehicles are smaller and runs at higher efficiencies for even longer
time which results in the significant fuel economy. There are several research and development
efforts continuously going on in the improvement of the ICE in terms of efficiency which is still
a main task for engineers. There are several methods being followed from the past 20 years to
achieve this such as downsizing the engine which doubles the efficiency and one more efficient
technology which is turbo chargers or variable valve timing which is really efficient to achieve
greater efficiencies but, most engines are still not equipped with this technology because of the
cost constraints.
Hybrid electric vehicles (HEV):
A hybrid electric vehicle (HEV) is a vehicle that runs on combination of conventional ICE
systems with any electric propulsion system or hybrid drivetrain. The electric powertrain system
offers high fuel economy and better performance compared to conventional vehicles. There are
mainly 2 components in HEV where one component is assigned for the energy storage purpose
whereas the other component converts the fuel into useful energy. There are significant reasons
and advantages in using the hybrids when compared to conventional ICEs which are:
● Provides better performance and also higher fuel economy.
● Very efficient for long term operating range with the combustion of liquid fuels.
● Offers higher energy densities.

There are disadvantages like poor fuel economy and environmental pollution due to release of
pollutants from conventional ICEs when compared to HEVs. Some important reasons for poor
fuel economy are;
● The prescribed efficiency characteristics of the fuel engine do not match with the real
driving conditions.
● Waste of useful kinetic energy while applying brakes often in urban driving conditions.
● Energy loss due to idling of engine and standby.
● Poor performance in automatic hydraulic transmission with low efficiency in current
stop-and-go driving conditions of the vehicle.
Battery electric vehicles BEVs on the other hand possess some advantages when compared to
conventional ICE vehicles, such as high energy efficiency and zero tailpipe emissions. But, the
limited range and time constraint for long time charging makes BEV less competitive over ICE.
BEV has low energy density of the batteries compared to the liquid conventional fuels. But,
HEVs process the best features that are combined from both the sources which utilizes the
advantages of both BEV and ICE. This ultimately results in overcoming the individual downfalls
or disadvantages in each. HEV consists of extra components and is a bit complex when
compared to conventional ICEs which makes HEV more expensive than conventional ICE. But,
HEV is not as expensive as BEV which has major expenses on high cost batteries.
Battery Electric Vehicles (BEV):
BEVs are quiet, comfortable and clean when compared to ICE vehicles. As mentioned earlier the
energy storage density is low in BEVs and also the range is very limited which makes ICE
dominant. Consequently BEVs almost vanished by the late 1930s. But, due to prevailing energy
crisis and climate concerns the engineers and automotive industries are again rethinking to build
BEV. They want to improve the efficiency and increase the storage density and make it
environmentally friendly which results in the increased urban air quality. Battery vehicles
consist of an electric motor instead of an ICE for traction purposes. The characteristics of the
BEV and HEV battery packs are very different. The BEV battery pack has high specific energy
while the HEV battery pack has high specific power. Since the motor in a power-assist (grid-
independent) HEV is used intermittently and must be capable of producing high power for short