Technology - Advancement Of Fuel Cells On The Automotive Front
(This article is sponsored by The Boston Group)
The area of fuel cells poses as a major challenge to various conventional methods of producing electric power. This article covers the history of the fuel cells, the way they work and their application in the automotive domain.
The history of the fuel cells go as early as 1839, when Sir William Grove (often referred to as the "Father of the Fuel Cell") discovered that it might be possible to generate electricity by reversing the electrolysis of water. It was not until 1889 that two researchers, Charles Langer and Ludwig Mond, coined the term ¡§fuel cell¡¨ as they were trying to engineer the first practical fuel cell using air and coal gas. While further attempts were made in the early 1900s to develop fuel cells that could convert coal or carbon into electricity, the advent of the internal combustion engine (ICE) temporarily suppressed any hopes of further development of the nascent technology. Francis Bacon developed what was perhaps the first successful fuel cell device in 1932, with a hydrogen-oxygen cell using alkaline electrolytes and nickel electrodes. Due to a substantial number of technical hurdles, it was not until 1959 that Bacon and company first demonstrated a practical five-kilowatt fuel cell system. In 1960s, practical realization of this excitingly new technology followed up in significant applications in the U.S. space program. In more recent decades, a number of manufacturers ¡V including major automakers ¡V and various federal agencies have supported ongoing research into the development of fuel cell technology for use in fuel cell vehicles (FCV) and other applications.
The considerable increase in the world population has led to an immediate need for power which in turn has made us realize the importance of non-conventional energy sources such as fuel cells. This growth in population has also forced an increase in the number of automobiles, which in turn increases the environmental challenges. Therefore, one important reason for the development of fuel cells is the reduction in amount of poisonous emissions as compared to the conventional IC engines. Moreover, they have marginally higher conversion efficiencies as compared to the IC engines and therefore are one of the potential sources for transportation applications.
A fuel cell is an energy conversion device that generates electricity and heat by electrochemically combining a gaseous fuel (hydrogen) and an oxidant gas (oxygen from the air) through electrodes and across an ion-conducting electrolyte. During this process, water forms at the cathode exhaust. The fuel cell does not run down or require any recharging; unlike a battery, it will produce energy as long as there is a supply of fuel and oxidant. Compared with thermal engine approach to chemical energy conversion, fuel cell technology is most certainly innovative. A thermal engine uses the heat generated by unconstrained chemical reaction to expand a working fluid, which when cooled and contracted performs mechanical work. This operation is subject to the well-known Carnot conversion limitation.
(¡§Carnot limit¡¨ limits the efficiency of the heat engines by its dependence on maximum and minimum temperature limits of the engine, ƒØcarnot = 1-(Tc/Th), where Tc and Th are in Kelvin.)
A fuel cell performs direct conversion of chemical energy available in a chemical reaction to direct current electrical work, which when transformed into mechanical work, by means of the electric motor, is highly efficient. The efficiency of a fuel cell stack is currently in the range of around 60% and that of the fuel processor is around 85% and research is underway to improve these figures. There might also be inefficiencies due to less efficient test cycle conditions which include start-up and transient driving conditions. Therefore, fuel cell efficiency, in general is only marginally better than the efficiency of the internal combustion engines.
(Ritesh Agarwal received his B.Tech from IIT Kanpur, his M.S. from Tufts University and is currently a Ph.D candidate at Virginia
Polytechnic Institute and State University. )
The fuel processor based fuel cells can operate on gasoline (so a new infrastructure is not needed) but they are bulkier and less efficient as compared to the direct hydrogen fuel cell. On the other hand, the direct hydrogen fuel cells require a hydrogen infrastructure for the technology to succeed in the automotive domain. Few companies are working on the technology of storing hydrogen onboard the vehicle effectively by using either high pressure storage tanks or metal hydride. Other than direct hydrogen and gasoline there are other fuels like methanol, natural gas that continues to arouse interest in this emergent technology.
Irrespective of the choice of fuel or infrastructure used, fuel cell technology faces substantial challenges and needs to prove its viability in the next few years. Conventional power sources for vehicles will continue to advance and provide strong competitive pressure. To justify its place in the world, fuel cells have to be cost effective, fuel efficient and have fewer emissions to outperform the conventional engine technology.
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