Development and comparative analysis of a pure fuel cell configuration for a light commercial vehicle

Abstract

Fuel cell electric vehicles help hybrid and battery electric vehicles to reduce vehicle emissions. Fuel cells are more appealing since, like internal combustion engines, they provide energy as long as fuel is supplied while doing so with less energy conversion and little or no emissions. In this study, the energy and fuel consumption values of a vehicle's internal combustion engine and fuel cell configurations were compared on a tank-to-wheel basis. First of all, a fuel consumption model was created for the conventional vehicle with 1.3 diesel engine. Subsequently, the fuel cell configuration of the same vehicle was designed by selecting a suitable fuel cell, electric motor, battery, and transmission. Then, the fuel cell vehicle configuration’s hydrogen and energy consumptions were calculated. The equivalent diesel consumption of the fuel cell vehicle was determined to be 3.38 L/100 km at the end of the study, which is 32% better than an Internal Combustion Engine vehicle. Also, with theoretical regenerative braking in the fuel cell electric vehicle, consumed traction energy can be reduced by 27%, while with practical regenerative braking, 55% of the braking energy can be recovered, and the traction energy can be reduced by 15%. On the other hand, since there is no regenerative braking system in the conventional vehicle, all of the braking energy is lost as heat.

Full text

Vol.:(0123456789)
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International Journal of Environmental Science and Technology
https://doi.org/10.1007/s13762-022-04629-3
ORIGINAL PAPER
Development andcomparative analysis ofapure fuel cell
configuration foralight commercial vehicle
M.Tekin1 · M.İ.Karamangil1
Received: 6 June 2022 / Revised: 10 October 2022 / Accepted: 21 October 2022
© The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2022
Abstract
Fuel cell electric vehicles help hybrid and battery electric vehicles to reduce vehicle emissions. Fuel cells are more appeal-
ing since, like internal combustion engines, they provide energy as long as fuel is supplied while doing so with less energy
conversion and little or no emissions. In this study, the energy and fuel consumption values of a vehicle's internal combus-
tion engine and fuel cell configurations were compared on a tank-to-wheel basis. First of all, a fuel consumption model was
created for the conventional vehicle with 1.3 diesel engine. Subsequently, the fuel cell configuration of the same vehicle was
designed by selecting a suitable fuel cell, electric motor, battery, and transmission. Then, the fuel cell vehicle configura-
tion’s hydrogen and energy consumptions were calculated. The equivalent diesel consumption of the fuel cell vehicle was
determined to be 3.38L/100km at the end of the study, which is 32% better than an Internal Combustion Engine vehicle.
Also, with theoretical regenerative braking in the fuel cell electric vehicle, consumed traction energy can be reduced by
27%, while with practical regenerative braking, 55% of the braking energy can be recovered, and the traction energy can
be reduced by 15%. On the other hand, since there is no regenerative braking system in the conventional vehicle, all of the
braking energy is lost as heat.
Keywords Energy consumption· Fuel cell vehicles· Fuel consumption· Greenhouse gases· Internal combustion engine
Abbreviations
ADVISOR ADvanced VehIcle SimulatOR
BEV Battery Electric Vehicles
bmep Brake mean effective pressure
BSFC Brake Specific Fuel Consumption
EM Electric Motor
EUDC Extra Urban Driving Cycle
FC Fuel Cell
FCEV Fuel Cell Electric Vehicles
FHDS Federal Highway Driving Schedule
FUDS Federal Urban Driving Schedule
HEV Hybrid Electric Vehicles
ICE Internal Combustion Engine
ICEV Internal Combustion Engine Vehicle
NEDC New European Driving Cycle
PEM Proton Exchange Membrane
PSAT Powertrain System Analysis Toolkit
TTW Tank-to-Wheel
UDC Urban Driving Cycle
WLTC Worldwide harmonized Light-duty vehicles
Test Cycles
WTW Well-to-Wheel
List of symbols

m
Instantaneous fuel consumption
a Acceleration
Af Frontal area
Cd Drag coefficient
D Driving distance
EFC Energy of the FC
EICE Energy of the ICE
Eregen. Regenerative energy
Faero Aerodynamic resistance force
Fgrade Grade resistance force
Frolling Rolling resistance force
Ftraction Traction force
g Gravitational acceleration
Hu,H2 Lower heating value of hydrogen
id Ratio of final drive
ig Ratio of gearbox
Editorial responsibility: Fatih Şen.
* M. Tekin
mervetekin@uludag.edu.tr
1 Department ofAutomotive Engineering, Bursa Uludag
University, 16059Bursa, Turkey

International Journal of Environmental Science and Technology
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Jd Polar moment of inertia of differential
Je Polar moment of inertia of engine
Jp Polar moment of inertia of primary shaft of
the gearbox
Jpr. Polar moment of inertia of propeller shaft
Js Polar moment of inertia of secondary shaft
of the gearbox
Jw Polar moment of inertia of wheels
k Regenerative braking coefficient
meq Equivalent of the vehicle
mH2 Amount of hydrogen consumed
mv Vehicle curb mass
n Engine speed
Paux Power of the auxiliary systems
Pbrake Braking power
PFC Fuel cell input power
PICE ICE power
Rw Wheel radius
TEM EM torque
TICE ICE torque
v Vehicle speed
Vfuel Fuel consumption
VH Engine displacement
vw Wind speed
α Road slope angle
ηEM Electric motor efficiency
ηFC Fuel cell efficiency
ηt Efficiency of powertrain
μ Rolling coefficient
ρ Air density
ρfuel Density of fuel
ω
Angular speed of engine
Introduction
According to the 2021 Emissions Gap Report (2021), exist-
ing climate policies would result in a global temperature
increase of 2.7°C by the end of the century. It was agreed
in the COP26 (Conference of the Parties) summit in 2021
that greenhouse gas emissions should be decreased by at
least 55% net by 2030 to keep the temperature rise to 1.5°C
(UNEP 2021). Road transport accounts for 15% of global
emissions (Ritchie 2020). Regulations targeting 95 gr CO2/
km for European Union fleet-wide cars have been intro-
duced for the 2020–2024 period to meet the Paris Agree-
ment's targets and reduce fuel consumption costs (ec.europa.
eu 2020). These goals are impossible to accomplish with
Internal Combustion Engine vehicles (ICEV). In this con-
text, electric vehicles have gained even more importance
with the dissemination of zero-emission vehicles and the
commitment to reach 100% zero-emission vehicle sales by
2040 (www. gov. uk 2021) by the signatory governments of
the Paris Agreement.
Electric vehicles are divided into three groups: (1) Hybrid
Electric Vehicles (HEV), (2) Battery Electric Vehicles
(BEV), and (3) Fuel Cell Electric Vehicles (FCEV). While
there are still challenges in the spread of this technology, it
is promising (Chłopek etal. 2018). Although hybrid electric
vehicles are an excellent intermediate step between conven-
tional and battery electric vehicles, they do not always help
to reduce emissions. Bagheri etal. (2021) have stated that
hybrid electric vehicles release equal levels of pollution to
conventional vehicles depending on driving style, and hybrid
electric vehicles even emit higher emissions in urban driv-
ing owing to more cold starting events of the ICE. Battery
electric vehicles have high energy conversion efficiency,
but one of the biggest challenges of batteries is limited
energy storage capacity (Sweeting and Hutchinson 2011)
and, consequently, limited range. In addition, charging the
battery requires a long time, such as a few hours. Although
fast charging technology can charge it in shorter times, this
negatively affects the battery's health. Fuel cells are similar
to internal combustion engines. As long as the fuel is sup-
plied, it continues to produce energy, but with less energy
conversion processes, higher efficiencies and, zero harmful
gas emissions (Manoharan etal. 2019). On the other hand,
fuel cells provide refueling times as short as five minutes, as
in conventional vehicles (Abderezzak etal. 2017; Ahn and
Rakha 2022). Also, fuel cells provide advantages in light-
ness, volume, emission, and range (Thomas 2009; Hardman
and Tal 2018).
During vehicle operation, the fuel cell produces no emis-
sion gases. The exhaust gases emitted mostly arise from the
production of hydrogen and fuel cell components during
the life cycle of a fuel cell (Pehnt 2001; Yu etal. 2021).
Hydrogen is produced from fossil or renewable energy
sources with different methods. For example, it is produced
from steam reforming natural gas, partial oxidation, solar
energy, or wind energy. However, the amount of emissions
released in hydrogen production by these methods is much
lower than that of conventional vehicles (Wilberforce etal.
2017). According to Haseli etal. (2008), when the hydrogen
produced by steam reforming is used in a fuel cell vehicle,
the CO2 released annually is approximately 54% less than
that of a diesel vehicle. In another study, Liu etal. (2020)
stated that the use of hydrogen produced from natural gas
by steam reforming in a fuel cell vehicle releases 15–45%
less green gas emissions than gasoline-powered vehicles.
Because of the benefits mentioned above, fuel cells, previ-
ously preferred in aviation and military applications, have
started to attract attention in vehicle applications for the last
30years (Ellinger etal. 2001).
Various studies in the literature compare fuel cell elec-
tric vehicles to a battery and hybrid electric vehicles as

International Journal of Environmental Science and Technology
1 3
well as conventional vehicles in terms of fuel consump-
tion (Ahluwalia etal. 2004; Chubbock and Clague 2016;
Correa etal. 2017; Liu etal. 2020), performance (Pear-
son etal. 2011; Ragheb etal. 2013), life cycle assess-
ment (Zamel and Li 2006; Ahmadi and Kjeang 2017;
Yang etal. 2020) and exergy (Braga etal. 2014). Liu
etal. (2020) compared the WTW (Well-to-Wheel) of fuel
cell electric vehicles with conventional vehicles. For this
reason, they conducted analyses in the GREET program
for Toyota Mirai and Mazda 3 vehicles. They found that
even using fossil fuel-induced hydrogen, fuel cell electric
vehicles consume 5–33% less fossil energy. The amount
of emissions released may be 15–45% less on fuel cell
vehicles. Ahluwalia etal. (2004) compared the ICE and
fuel cell configurations for compact, mid-size, and sport
utility vehicles. Simulations were performed in the PSAT
(Powertrain System Analysis Toolkit) program using the
FUDS (Federal Urban Driving Schedule) and FHDS (Fed-
eral Highway Driving Schedule) drive cycles. In a fuel
cell configuration, they have achieved a fuel economy of
2.7 times for compact, mid-size vehicles and 2.5 times
the fuel economy for sport utility vehicles. Chubbock and
Clague (2016) have compared ICE and fuel cell use as a
range extender in an electric vehicle. Forty percent less
fuel consumption is achieved when using a fuel cell as a
range extender for the same range. Correa etal. (2017)
have done WTT (Well-to-Tank) and TTW (Tank-to-Wheel)
analyses for five different configurations of buses. They
have analyzed diesel, hybrid, compressed, and natural gas
enriched with hydrogen, PEM (Proton Exchange Mem-
brane) fuel cell, and battery electric vehicles using EUDC
(Extra Urban Driving Cycle) and the UK driving cycles
for different ranges. At the end of the work, they stated that
battery electric vehicles are more competitive for short-
range, while fuel cell electric vehicles are highlighted for
long-range.
This study compares the Tank-to-Wheel (TTW) energy
and fuel consumption of an internal combustion engine vehi-
cle and its fuel cell configuration. The internal combustion
engine vehicle used in this study is a mass-produced vehicle.
The fuel cell configuration of the vehicle is not produced.
In this study, a fuel cell configuration is designed for the
existing conventional vehicle. In the previous studies which
compared fuel cell electric vehicles with other vehicle con-
figurations, vehicle parameters such as vehicle weight and
frontal area are different in each configuration. In this study,
a comparison has been studied, assuming that all param-
eters are the same for both vehicle configurations except for
propulsion components. In this framework, firstly, a mass-
produced 1.3L diesel engine light commercial vehicle was
selected. Its fuel cell configuration was then designed using
a suitable fuel cell, electric motor, battery, and gearbox.
Backward-facing vehicle models based on NEDC were
created for both vehicle configurations, then energy and fuel
consumption values were compared. The vehicles’ models
and NEDC cycle are introduced in the following sections.
This study carried out in Department of Automotive
Engineering, Bursa Uludag University, Bursa, Turkey dur-
ing 2018- 2019.
Materials andmethods
There are two approaches to vehicle modeling. The first is
forward-facing modeling, and the second is backward-facing
modeling (Markel etal. 2002; Chubbock and Clague 2016).
The driver is the starting point in forward-looking models,
and the accelerator and brake pedal signals are generated
based on the driver's behavior. A controller is used to mini-
mize the error between the driver request and the system
response in the forward-facing model. In the backward-fac-
ing vehicle model, the starting point is a driving cycle. The
power/torque requested from the wheels is calculated for
each time step depending on the drive cycle speed. A back-
ward-facing computation is conducted from the wheels to
the power source, taking into account each component in the
driveline until the fuel or energy consumption is calculated.
One of the disadvantages of the backward-facing approach
is the lack of feedback or a controller. However, it is still a
valuable and straightforward approach to calculate fuel and
energy usage (Markel etal. 2002; Ehsani etal. 2018).
In this study, backward-facing model was selected, and,
vehicles’ mathematical models were created in MATLAB.
Firstly, for conventional vehicle with a 1.3L diesel engine,
fuel consumption, traction, and braking energy were calcu-
lated according to the NEDC. Then, the hydrogen consump-
tion and energy values were calculated by designing the
same vehicle's fuel cell configuration. A suitable fuel cell,
battery, electric motor, and transmission were selected for
this purpose. The parameters of the vehicle and the environ-
ment are given in Table1. These parameters were assumed
identical for both vehicle configurations. The parameters
of the internal combustion engine, fuel cell, electric motor,
and traction system components are given in the following
sections.
New European driving cycle (NEDC)
The NEDC cycle, developed in 1980, includes an urban
driving cycle (UDC) and an extra-urban driving cycle
(EUDC). The urban driving cycle consists of an ECE15
cycle that repeats four times. The duration of one ECE15
cycle is 195s, and its range is approximately 1km. The
extra-urban driving cycle, following UDC, is 400s and
approximately 7km. In the end, the total duration of an
NEDC cycle is 1180s, with a total range of 11km. The

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graph of the time-speed profile for the cycle is given in
Fig.1. The figure shows that the NEDC is a repetitive
and stationary cycle. Therefore, a new drive cycle, WLTC
(Worldwide harmonized Light-duty vehicles Test Cycles),
was developed and introduced as NEDC does not reflect
the actual emissions (Tutuianu etal. 2014; Marotta etal.
2015). However, there is no drawback in performing the
simulations forNEDC instead of WLTC since the internal
combustion engine vehicle used in this study has a Euro 4/
Euro 5 emission level.
Longitudinal vehicle motion equations
The vehicle must overcome forces from the ground to the
wheel to move. These are forces of roll, slope, and aerody-
namic resistance.Furthermore, the inertia force generated
by the rotating parts of the vehicle also creates resistance to
movement.The traction force is the sum of these four forces.
In order to calculate the fuel consumption with the back-
ward-facing vehicle model, the traction force must be known
first. It is essential for determining how much power the
power source should produce and is expressed as in Eq.1.
where
Ftr action
is traction force (N) at wheels,
𝜇
is the rolling
resistance coefficient (−), mv is the vehicle mass (kg), g is
the gravitational acceleration (m/s2),
𝛼
is the slope angle of
the road (°),
𝜌
is the density of air (kg/m3),
Cd
is the drag
coefficient (−),
Af
is the frontal area of the vehicle (m2),
v
is the vehicle speed (km/h),
vw
wind speed (km/h),
meq
is
the equivalent mass of the vehicle (kg). When calculating
the inertial force, the equivalent vehicle mass (meq) must be
taken into account. The equivalent vehicle mass is obtained
by including the engine's inertia, the primary and secondary
shafts of the gearbox, and the wheels in the vehicle mass
(Eq.2).
where
Je,Jp,Js,Jd
and
Jw
are the rotational inertias (kg m2)
of the engine, the primary shaft of the gearbox, the second-
ary shaft of the gearbox, differential, and wheel, respectively.
ig
is the ratio of the gearbox,
id
is the ratio of final drive, and
Rw
is the radius of the tire (m).
Fuel consumption model: internal combustion
engine
The flow chart in Fig.2 summarizes how the fuel con-
sumption of a conventional vehicle is calculated in this
paper.The vehicle parameters and driving cycle are
defined in the model as input values.The instantaneous
fuel consumption value is calculated from the engine's
specific fuel consumption map for each second of the cycle
according to the defined input values.The specific fuel
consumption map has engine speed on the horizontal axis
and brake mean effective pressure (bmep) on the vertical
axis.The specific fuel consumption value can be read on
the map depending on these two values. Therefore, it is
necessary to calculate the bmep and engine speed at one
second intervals.
The ICE power must first be known to calculate bmep
(brake mean effective pressure). The power produced by
the internal combustion engine can be calculated using the
drive power demanded by the wheels.ICE power is trans-
mitted to the wheels via drivelines, so the transmission
ratio and driveline efficiency must be considered. In this
case, the internal combustion engine (PICE-kW-) power can
be expressed in Eq.3.
(1)
F
tr action
=F
rolling
+F
grade
+F
aero
+F
inert ia
=𝜇mvgCos(𝛼)+mvgSin(𝛼)
+1
2
𝜌CdAf(v∓vw
3.6
)2
+meqa
[N]
(2)
m
eq =mv+
Je
R2
w
i2
gi2
d+
J
p
R2
w
i2
gi2
d+
Js
R2
w
i2
d+
Jd
R2
w
+∑Jw
R2
w
[kg]
Table 1 Parameters of vehicle and environment
Parameter Symbol Value Unit
Vehicle parameters
Vehicle curb mass mv1345 kg
Frontal area Af2.7 m2
Drag coefficient Cd0.38 –
Wheel radius Rw0.31 m
Inertia of wheels and axles Jw3.6248 kg m2
Inertia of propeller shaft Jpr 0kg m2
Efficiency of powertrain ηt0.95 –
Environment parameters
Air density ρ1.226 kg/m3
Gravitational acceleration g9.81 m/s2
Wind speed vw0 km/h
Road slope angle α0 °
Rolling coefficient μ0.013 –
Fig. 1 New European Driving Cycle (NEDC) (Marotta etal. 2015)

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where TICE is the engine torque (Nm), ω is the angular veloc-
ity of the engine (rad/s), ηt is the powertrain efficiency and
ig
and
id
are the gearbox and differential gear ratio, respec-
tively. The BSFC (Brake Specific Fuel Consumption) map
is used to determine instantaneous fuel consumption. The
BSFC map in Fig.3 has motor speed on the x-axis and bmep
on the y-axis. This map is defined as a look-up table in the
model. Firstly, the model calculates engine speed and bmep.
Engine speed can be calculated with the help of the wheel
speed. Brake mean effective pressure (bmep-bar-) can be
calculated as in Eq.4. Then, instantaneous fuel consumption
is calculated by interpolation from the look-up table based
on these two values.
(3)
P
ICE =
T
ICE𝜔
1000 =
T
ICE
2
𝜋
n
1000.60 =
F
tr action
R
w
𝜂
t
i
g
i
d
2𝜋n
1000 ⋅60
[kW]
where PICE shows the effective power of ICE (kW), n is
engine speed (rpm), and VH is engine displacement (L). The
fuel consumption of the vehicle in L at 100km can be cal-
culated by dividing the cumulative fuel consumption by fuel
density and distance as follows:
where Vfuel is the cumulative fuel consumption (L/100km),
m
is the instantaneous fuel consumption (kg/h), n is the
engine speed (rpm), and ρfuel is the fuel density (kg/L) and
D is the driving distance (km). Details on the fuel consump-
tion model of the internal combustion engine vehicle can
be found in Tekin and Karamangil (2022). The energy used
by the vehicle is expressed by the integral of instantaneous
power (Eq.6).
The characteristics of the internal combustion engine, the
overall gear ratios, and the specific fuel consumption map
of the engine are given in Table2 and Fig.3, respectively.
Fuel consumption model‑fuel cell electric vehicle
The driving power demanded from the wheels was initially
calculated using the same method as in the previous section
to calculate the power consumed by the fuel cell. In addi-
tion to driveline efficiency, the fuel cell and electric motor
efficiencies must be taken into account because the power
generated by the fuel cell is first transmitted to the electric
motor and then to the wheels via the transmission. There are
three situations here.The first is the traction, i.e., the traction
(4)
bmep =
1200P
ICE
nVH
[bar]
(5)
V
fuel =
1
3600 ∑m(n,bmep)100
𝜌
fuel
D[L∕100
km]
(6)
E
ICE =
∫
PICE
dt
Fig. 2 For a conventional vehicle, flowchart for calculating fuel consumption based on backward modeling
Fig. 3 BSFC map of the diesel engine at regime temperature

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force is positive values.The second situation is braking, i.e.,
the value of the traction force is negative.The third situation
is the vehicle is stationary (wheel speed is zero).In this case,
the traction force is zero.The vehicle only consumes energy
for auxiliary systems (air conditioning, headlights, etc.). The
power flow in these three cases is summarized in Fig.4.
Fuel cell power can be calculated with Eq.7. In this state-
ment, the electric motor moment (
TEM
) and angular velocity
(
𝜔
) are calculated as in the previous section. Motor torque
is calculated by dividing the wheel torque (
Ftr action
⋅
Rwheel
)
by the efficiency (
𝜂
) and transmission ratio (
ig
⋅
id
) of the
driveline. It is noted that the transmission ratio is different
for the two vehicle configurations because the gear boxes of
the two vehicles are different. The power required for the
auxiliary systems is also considered in Eq.7 because it is
provided by the fuel cell.
where
PFC
is the fuel cell input power (kW),
𝜂EM
is the elec-
tric motor efficiency,
Paux.
is the power of the auxiliary sys-
tems (W) and
𝜂FC
is also fuel cell efficiency. Because no
power is transmitted to the wheels at zero vehicle speeds, the
fuel cell will only generate power for auxiliary systems. The
amount of hydrogen consumed can be calculated by dividing
the energy consumed by the fuel cell by the lower heating
value of the hydrogen (Eq.8).
where
mH2
is the amount of hydrogen consumed (kg),
EFC
is the fuel cell energy (kJ), and
Hu,H2
is the lower heating
value of hydrogen (kJ/kg). During braking, the electric
motor operates as a generator, which stores the energy from
the wheels in the battery. However, in terms of vehicle and
passenger safety, not all of the energy generated in braking
can be recovered. A certain part of the total braking energy
can be recovered to ensure safe braking. Equation9 refers
to the energy recovered during braking.
(7)
P
FC =
T
EM⋅
𝜔
𝜂EM
+P
aux
1000 ⋅𝜂
FC
(8)
m
H2=
EFC
H
u,H2
=
∫
PFCd
t
H
u,H2
where
Eregen.
is the regenerative energy,
Pbrake
is braking
power and k is the regenerative braking coefficient. Popi-
olek etal. (2019) found that the recovery rate for the NEDC
is 0.55. In this paper, the analysis was also carried out by
accepting the regenerative braking coefficient of 0.55.
Instead of the internal combustion engine, the same
power FC_ANL50H2 fuel cell and MC_PM49 electric
motor were selected from the ADVISOR (ADvanced VehI-
cle SimulatOR) (MATLAB and ADVISOR Toolbox Release
2013a, The MathWorks, Inc., Natick, Massachusetts), and
their efficiency maps (Fig.5) were used for the fuel cell
electric vehicle configuration. In addition, the battery with
a capacity of 25 Ah was chosen from the ADVISOR. The
single-stage transmission of the Mitsubishi i-MIEV has
been selected to be compatible with the electric motor. The
power required for the auxiliary systems was accepted as
500W. Parameters of the fuel cell, electric motor, and gear-
box are given in Table3. All other vehicle parameters given
in Table1 have been accepted as the same for the fuel cell
vehicle configuration.
Model validation
The model results for the ICE vehicle were compared with
the tests obtained from the chassis dynamometer. The dif-
ferences between modeling and test values given in Table4
are acceptable for model verification.
The fuel cell vehicle configuration model is based on
Friedman etal.'s research (2000). Since the fuel cell con-
figuration is a simulation design, it could not be verified with
real vehicle tests. Their study determined the fuel consump-
tion value for the pure fuel cell design of the Ford Taurus
car was 14g/mile for the FTP-75 cycle. The hydrogen con-
sumption value of the Ford Taurus car was calculated using
the model used for the presentstudy as 14.22g/mile. The
difference is within acceptable bounds due to the uncertainty
of some vehicle data in the reference study.
(9)
E
regen.=
∫(
Pbrake k
)
d
t
Table 2 Specifications of ICE and overall gear ratios
Engine specifications
Engine displacement 1.3 L
Engine power 50kW
Inertia of ICE 0.2041 kg m2
Overall gear ratios
1st 2nd 3rd 4th 5th
16.31 8.54 5.51 3.93 3.03

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Results and discussion
In this section, two vehicle configuration is compared in
terms of traction power, fuel consumption, and efficiency.
Only the last ECE cycle and the extra-urban driving cycle
have been drawn instead of the entire cycle in the figures to
prevent the complexity. Energy and fuel consumption values
are calculated, considering the entire driving cycle. Figure6
shows the instantaneous traction power curves for two vehi-
cles. The internal combustion engine vehicle shows that the
traction effort is slightly higher at some points, especially in
the urban cycle. The resistance forces acting on both vehicles
are the same. Minor differences are due to inertial forces.
Because ICE and EM inertias are different and a different
gearbox is used, the inertial forces change, even though very
small. This changes the total traction effort and, therefore,
the energy consumed. The total traction energy is 4.86MJ
for ICEV and 4.73MJ for FCEV. The braking energies for
ICEV and FCEV are 1.35MJ and 1.30MJ, respectively.
Figure7 shows the instantaneous fuel consumption of
the vehicles depending on the traction power requested
from the wheels. The fuel consumption curve draws a sim-
ilar profile in both vehicles. The heating value of diesel
fuel is 42.6MJ/kg, while the heating value of hydrogen
fuel is 120MJ/kg in this comparison. Hydrogen's high
heating value is also advantageous for fuel cell vehicles.
Fig. 4 Flow chart of fuel consumption calculation for the fuel cell electric vehicle

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Since the ICE vehicle has fuel cut-off and start/stop tech-
nologies, fuel power consumption is zero at the points
where the vehicle stops and at the engine speed over
1000rpm during deceleration. However, since the energy
required for auxiliary systems is also provided by the fuel
cell, some hydrogen continues to be consumed even if the
vehicle speed is zero.
The conventional vehicle consumes 4.96L of diesel fuel
per 100km, while the fuel cell electric vehicle consumes
only 1kg of hydrogen. Table5 also provides hydrogen con-
sumption as diesel equivalent for a direct comparison. The
diesel equivalent of the hydrogen consumed by fuel cell
electric vehicle is 3.38L/100km. This means the fuel cell
saves 32% compared to the ICE vehicle architectures.
The average efficiency of the electric motor is 94% in
the UDC and 90% in the EUDC. The average efficiency
of the electric motor during the NEDC cycle is 93%. Fuel
cell efficiency is 26% in the UDC and 47% in the EUDC.
A higher fuel cell efficiency in the EUDC is due to the fuel
cell characteristic. When Fig.8 is examined, fuel cell effi-
ciency is better at relatively high power. At very low loads,
the fuel cell provides poor efficiency. With increased power,
efficiency increases to a certain point and then decreases.
The average fuel cell efficiency during NEDC is 33%, and
it has dropped in UDC because the fuel cell consumes very
low power for only auxiliary systems at standing points.
Figure9 shows the traction energy and the recovered part
of that energy. The highest braking energy and the recovered
energy were achieved in the extra-urban cycle. It is impor-
tant to note that this graph is obtained for the energy from
the wheels. There will be losses when this recovered energy
is delivered to the battery.
The values of the braking energy, loss energy, and recov-
ered energy for both vehicle configurations are summarized
in Table6. Fuel cell electric vehicles provide advantages in
energy consumption since both fuel cell efficiency is higher
than the ICE, and they provide the opportunity to recover
some of the braking energy.
Fig. 5 a Electric motor efficiency map (MC_PM49) and b fuel cell system efficiency curve (FC_ANL50H2)
Table 3 Fuel cell vehicle parameters
Motor
Power 49kW
Torque 274.4 Nm
Peak efficiency 0.96
Inertia of motor 0.0507 kg m2
Fuel cell system
Net power 50kW
Peak efficiency 0.60
Battery and DC/DC converters
Battery capacity 25 Ah
Charge/discharge efficiency %90
DC/DC converter efficiency %95
Overall gear ratio
7.065
Table 4 The differences between test and modeling results (for ICE
vehicle)
Test Modeling Δ %
UDC (L/100km) 6.00 5.86 − 2.33
EUDC (L/100km) 4.30 4.43 3
NEDC (L/100km) 4.90 4.96 1.22
CO2 emissions (g/km) 129 131.5 1.94

International Journal of Environmental Science and Technology
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Conclusion
In this study, fuel consumption values were calculated
by backward-facing modeling of the internal combustion
engine vehicle and its fuel cell configurations. The amount
of energy consumed was also compared. It should be noted
that with a calculation in the study, it was found that the
total weights of the propulsion system for the two configu-
rations were very close to each other. It is a fact that this
difference can increase in practical application. This study
explores the advantages of the fuel cell powertrain system
against the internal combustion engine powertrain system
for the same vehicle parameters. Therefore, calculations
were done with the acceptance that the vehicle weight and
other parameters had not changed.
At the end of the study, the following results were
obtained:
• Hydrogen consumption of FCEV configuration is found
1.01kg/100km under NEDC. Similar results were found
in similar studies calculating the hydrogen consumption
of a fuel cell vehicle in the literature. For example, Wang
Fig. 6 Traction powers of internal combustion engine vehicle (ICEV) and fuel cell electric vehicle (FCEV)
Fig. 7 Fuel consumption of internal combustion engine vehicle (ICEV) and fuel cell electric vehicle (FCEV)
Table 5 Fuel consumption values of ICEV and FCEV
UDC EUDC NEDC
ICEV (L/100km) 5.86 4.43 4.96
FCEV (L diesel/100km) 4.15 2.95 3.38
[kg H2/100km] [1.24] [0.88] [1.01]
Difference − 29% − 34% − 32%

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etal. (2021) found the hydrogen consumption for NEDC
to be 0.774kg/100km, Zhao etal. (2020) found approx-
imately 1.08kg/100km. These values can be further
improved with an energy management strategy between
the battery and the fuel cell.
• The fuel consumption of the ICE vehicle is
4.96L/100km at the end of the NEDC. The fuel con-
sumption equivalent of the fuel cell electric vehicle is
3.38L diesel/100km and provides 32% fuel economy
compared to the ICE vehicle.
Fig. 8 a Electric motor and b fuel cell system operating points
Fig. 9 Traction energy and recovered energy of fuel cell electric vehicle
Table 6 Comparison of
consumed and recovered energy
for the NEDC cycle
Traction
energy (MJ)
Regenerative
energy (MJ)
Net traction energy (MJ) Losses (MJ)
ICEV
Without regenerative braking 4.86 0 4.86 1.35 (braking)
Ideal regenerative braking 4.86 1.35 3.51 (% − 27) 0
FCEV
Without regenerative braking 4.73 0 4.73 1.30
Ideal regenerative braking 4.73 1.30 3.43 (% − 27) 0
Practical regenerative braking 4.73 0.71 4.23 (% − 15) 0.59

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• During the NEDC cycle, 1.35MJ of energy is consumed
braking in the ICE vehicle. 27%of traction energy could
be saved if all of this energy could be recovered. How-
ever, since there is no regenerative braking system in the
conventional vehicle, all of the energy used for braking
is lost as heat and friction.
• During the NEDC cycle, 1.30MJ of energy is required
for braking in the fuel cell electric vehicle. 27% of trac-
tion energy could be saved if all of this energy could be
recovered by regenerative braking. However, not all of
this energy can be recaptured in practice. 15%of the trac-
tion energy is saved if 55%of the braking energy can be
recovered.
• The internal combustion engine vehicle's fuel consump-
tion values are calculated considering the fuel cut-off
and start/stop strategies. As a result, the ICEV con-
sumes no fuel throughout the idling phases of the driving
cycle. However, because the auxiliary systems' power is
assumed to be provided by the fuel cell, FCEV continues
to consume hydrogen when idling. However, the above-
mentioned advantages of FCEVs over ICEVs are due to
their higher efficiency, energy recovery capabilities, and
higher heating value of hydrogen.
• The fuel cell is the only power source in the fuel cell
configuration. The fuel cell's low efficiency at low and
high power increases the amount of energy used. This
also reveals the energy management system's importance
in the energy consumed. The energy consumed will be
reduced by supplying the required power from the fuel
cell at operating points with high fuel cell efficiency and
from the battery at low and high power points.
• The Paris Climate Agreement's aims for lowering green-
house gas emissions in the transportation sector have
boosted the relevance of electric vehicles even more. As
a result of the clean and efficient energy they supply, fuel
cell electric vehicles will become more popular in the
near future. However, cost and infrastructural upgrades
are necessary for fuel cell vehicles to become more com-
monly utilized.
Declarations
Conflict of interest The authors declare that there are no known con-
flicts of interest associated with this publication.
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