IEEE Electrification Magazine - March 2018 - 52

its components degrade over time or from usage, and the
degradation accelerates when it is exposed to extreme conditions or pushed to exceed performance limits. one solution may be to develop components that demonstrate
higher performance than is required and use them in conditions well below their limits. However, this unreasonable
solution is not acceptable in the automotive market
because of cost issues. Further adding to this challenge, the
laws of nature do not allow some delicate components of
fuel-cell systems to outperform all conflicting requirements. For example, a proton-conducting membrane must
be thin and strong enough for higher proton conductivity
and the complete separation of hydrogen and oxygen,
respectively, although a thin membrane is inherently
weak and fragile. nonetheless, many researchers and
engineers are attempting to resolve these types of conflicts.
However, the situation is not hopeless. Techniques to
elongate the durability of fuel-cell systems are similar to

those for extending the lifespan of humans or living creatures. Fuel-cell system developers test their devices under
nearly all possible conditions, e.g., hot, cold, high pressure,
low pressure, humid, dry, steady, dynamic, high load, and
low load. Then, they identify the specific causes of the degradation and discover strategies to mitigate or prevent it.
The strategies are realized by actively controlling the temperature, pressure, humidity, gas flow rate, and response to
the electric power demand. indeed, modern FCevs are
equipped with: 1) various sensors to monitor physical
quantities; 2) real-time controllers to diagnose the health
status of the fuel-cell stack and to determine the optimal
operational conditions in various situations; and 3) actuators, which are called balance of plants, to realize the
required conditions (Figure 5).
The last two decades have seen a significant increase
in the lifespans of FCevs. Two key factors for this have
been the development of more durable materials, while, at
the same time, maintaining the
performance; and the onboard control system, which provides an
optimal environment that is delib2013
erately determined depending on
363 mi
the status and load demand of the
2018
fuel-cell system. early stage FCevs
60.0%
55.3%
260 mi
163 hp
barely survived a few hundred
134 hp
hours of operation, which was far
less than the required lifetime of a
decent passenger car. only a decade ago, developers endeavored
to create FCevs that were capable
of withstanding several-thousand
hours of operation, and, more
recently, attempted to design them
Efficiency
Driving Range
Power
to perform for 10,000 h. The increased
durability of FCevs is expected to
Figure 4. A representation of the improved performance of FCEVs.
cause the durability of the secondhand market value of the automobiles to rise as well.
Battery

Hydrogen Tank

Controller

Drive Motor

Fuel-Cell Stack

Balance of Plant

Figure 5. The schematic of an FCEV. (Image courtesy of Hyundai Motor Company.)

I EEE E l e c t r i f i c a t i on M a gaz ine / march 2018

Cost
despite the technological achievements, i.e., performance and durability, FCevs remain an expensive
option when compared to conventional (gasoline or diesel engines),
hybrid, and electric automobiles.
overcoming this price gap may
depend on government subsidies for environmentally friendly
vehicles; however, these subsidies are short-term, and the cost
of FCevs will need to be lowered
to attract customers.
one favorable point is that a
considerable portion of the cost of

Table of Contents for the Digital Edition of IEEE Electrification Magazine - March 2018