Journal
Review
Title
of the journal : Fuel Cells for the Long Haul, Batteries for the Spurts.
IEEE
SPECTRUM, January 2001.
Author
: Michael J. Riezenman
Reviewed
by : Tunku Emir Farhan Bin Tunku Ibrahim, 1127493.
This journal discusses the idea of
using a Fuel Cell system in the future automotive commercial industry. Either
this can be as another feasible alternative solution in order to reduce air
pollution by emissions or not. The author seems to compare the existing
alternative cars that use a lot of different types of power generator for a
vehicle instead of using the conventional ICE (Internal Combustion Engine),
such as Electric Vehicle (EV) that uses fully batteries and make it as energy
storage, HEV or Hybrid-Electric vehicle that is made up of both ICE and
electric motor to generate simultaneously the power of the car and also the
Fuel Cell vehicle that uses Hydrogen as the main source of energy that creates
electricity for the motor. The title of this journal may imply the general
distinct characteristic between the EV and FCV as a whole idea as an automotive
alternative.
First part of the writing, the author recaptures
the history of the first Hydrogen-fuel cell car which was a Ford Focus sedan
that was making its debut in 2000 at the 17th International Electric
Vehicle Symposium in Montreal. Back then, that kind of futuristic idea may not
be ever commercially produced to be thought of but it had clearly become a key
for the automotive industry to think about how to make into practical in the
reality. As the author says, “A product of Ford Motor’s new environmentally
focused Think Group, the hydrogen-carrying vehicle will never be commercially
available. But it marks a decisive change in the automotive industry’s thinking
about the future, making it one of the more important technobusiness
developments of recent times”.
According to the author, until the recent years, most of the environmental-concerned speakers and the automotive makers always refer the low-emission car to the Electric vehicle EV while definitely this particular vehicle technology is still looked as unfavourable alternative to the consumers. As the EVs use batteries as the main power source and energy storage, it is seemed to be unpractical and weighs too heavy. Furthermore, for a long-range journey these EVs would not be possible because of the limitation of energy that the batteries can stores with its limited space. Not only that, the average time taken for recharging the batteries is considerably long and finally the maintenance for the batteries becomes costly. So, this make the automotive market change its direction to look forward to another possible better alternative which is HEV, the hybrid electric vehicle.
According to the author, until the recent years, most of the environmental-concerned speakers and the automotive makers always refer the low-emission car to the Electric vehicle EV while definitely this particular vehicle technology is still looked as unfavourable alternative to the consumers. As the EVs use batteries as the main power source and energy storage, it is seemed to be unpractical and weighs too heavy. Furthermore, for a long-range journey these EVs would not be possible because of the limitation of energy that the batteries can stores with its limited space. Not only that, the average time taken for recharging the batteries is considerably long and finally the maintenance for the batteries becomes costly. So, this make the automotive market change its direction to look forward to another possible better alternative which is HEV, the hybrid electric vehicle.
The parallel HEVs basically uses both
ICE and the electric motor to propel the vehicle simultaneously which seemed to
be more convincing because this system does not only depend on the batteries as
the only energy storage for the electric motor to generate the power but the
engine also will sometimes drive the wheels while the car is at its cruising
speed. During this speed, the engine is actually producing its power at the
highest efficiency and producing its lowest emission. Not like the pure EVs,
the HEVs use the electric motor to drive the wheel but only when the car is
moving at low speed or moving the car from idle condition for a better
efficiency. Thus, the advantages of HEVs over the EVs are very clear and more
promising because you still can fill up the energy source at the gas station
like any other conventional car and not to worry about to charge the batteries
for a certain range of distance. Nevertheless, the author says, “The drawbacks
remain as like the conventional vehicles, HEVs are not zero-emission vehicles.
Worse, as they age (or if their maintenance is neglected) they risk becoming
serious polluters”.
Fuel
cells outfox technology forecasters
When the EVs seems to be unpractical in
terms of its sustainability, reliability, distant-range limitation and the cost
while the HEVs show better solutions but still create the main problem which is
creating emissions, the Fuel cell vehicle or the FCVs become another hope. The
author describe the FCV is another idea of the future that beyond the mind of
technology fortune-tellers like EVs did but in the opposite way. “Ten years ago
the conventional wisdom said that a good EV battery was just around the corner
whereas fuel cells were still a pipe dream. Not only has the battery progress
been disappointing, fuel cell progress has been truly spectacular”. This
suggests that the whole idea behind this FCV system is truly interesting and
practically promising to be realised compared to the EV system. Even though the
EV optimist believe that this battery powered vehicle will finally improve the
drawbacks and make it more viable, the FCV is still far more advantageous than
the EV primarily in terms of its range of distance and weight of the storage
itself.
It is obviously confusing to
differentiate between the concepts of both FCV and EV. Those are actually very
different in mechanism. The EV relies on batteries as the main energy storage
but FCV is a system that converts the chemical energy comes from the hydrogen
into electricity by electrochemical reaction. To make it clearer, this FCV
contains one major component which is fuel cell. This fuel cell is divided into
three elements which are anode, PEM or Proton-Exchange Membrane and cathode.
This simply extracts the positive ion from the hydrogen atom in the anode by
catalyst, and allows this positive ion to go through the PEM to reach the
cathode as to diffuse this positive hydrogen ion with the oxygen to create
water and heat. Meanwhile, during the extraction of hydrogen, the negative
charge ion cannot across the PEM so, it must goes to another path which is to
an electric circuit and finally this will generate electricity for the electric
motor to work. Like any other conventional cars, this FCV uses a fuel tank as
an energy storage and unlikely the EV that uses the batteries as energy storage
which is heavier and unsustainable.
Storing
the hydrogen
Until this part, the author has raised
another specific interesting issue regarding this FCV energy source. As he
says, “ although the hydrogen has a very high specific energy that almost 150
mega joules per kilogram and it is light that a litre of it pressurized to 35
MPa and weighs just 31 grams but definitely it only packs 4.4 MJ of energy.
Gasoline, by contrast, has a lower specific energy of about 50 MJ/kg, but a
litre is equivalent to about 30 MJ”. This clearly shows that even though the
hydrogen contains a higher specific energy than the gasoline but to make it
pressurized into one litre of liquid never produce higher energy compared to
gasoline. So, to put it into a context, a 200 L of hydrogen gas may not produce
the same total of energy of 200 L of gasoline. Nevertheless, fuel cell and
electric motor is still more efficient compared to ICEs but to make it fairly
efficient, it must goes up to 500 km range. But to make it so, it takes about 6
kg of hydrogen and has to be compressed to 35 MPa so that it will fill up to
200 L. This quantity of hydrogen also sacrifices the space for storage that it
could be double in size.
However, there are some experts in
nickel/metal-hydride battery who had found the solution of this storing issue.
They have applied its expertise and developed metal alloys that can store about
7 percent of their weight in hydrogen at the fairly low pressure of 200 kpa.
Now, even with the lower pressure of hydrogen it still can fill up 6 kg of gas
even with 120 L of volume. But the weight of the storage system remains a
problem, and the question remains, where is the hydrogen to come from? This
issue was raised as the existing infrastructures are not ready to install for
making hydrogen gas becomes commercial for production. Several major automakers
by the way have sponsored the development of compact chemical plants which is
called reformers. This is extracting hydrogen from common fuels like methanol
and gasoline. Moreover, a hydrogen fuel-cell system based on reformed gasoline
eliminates the infrastructure problem completely. Some issues regarding the
storing hydrogen as it is either safer than gasoline to travel along with or
not have been openly discussed but based on several recent developments, it is
proven experimentally that the storage if safer that even achieved more than
the standard level requirement. Thus, no issue of safety shall be raised
regarding the storage.
Electricity
to the rescue
Note that the production of hydrogen is
not only by using the reformers method that comes from fossil fuel to extract
the hydrogen. There is one aqueous solution of sodium borohydride (NaBH4) which
can yield hydrogen gas and a sodium borate (NaBO2) solution on exposure to a
catalyst. In fact, there is no drawback of using these minerals and likely it
is recyclable compared to traditional fossil fuels. Converting into NaBH4 for
fuel, then the resulting NaBO2 can be converted back into NaBH4 in an
electrochemical process yet the infrastructures for doing so has to be built.
Conclusion
It
is truly shown that this FCV idea of technology is really promising and much
more practical compared to any other future alternative vehicles especially the
EV in terms of its reliability, sustainability, cruising range, and its weight
and space. Yet this FCV may cost higher than that EV but because the FCV never
use batteries for storing the energy instead, it uses the fuel like hydrogen to
generate the electric power for the motor so it does provide a lower
maintenance cost compared to EV. As for EV, the batteries durability is not
everlasting so it demands the consumer to change them for roughly every 5 years.
The storing issues regarding this hydrogen gas and how to make into production
have been already discussed and come up with some possible solutions.