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 17^th 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. 

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.