Efficiency Of Fuel Cells
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Efficiency Of Fuel Cells
Article Introduction
Attention on fuel cells is increasing as the range of potential commercial applications expands. This includes automotive and power generation capabilities and highlights the improvements in efficiency and cost that have been achieved in recent years. However, there is often confusion regarding the disparate types of fuel cells, their advantages and disadvantages, and the time needed for commercialisation. Understanding of many of issues can only be realised by a broad understanding of the technology itself.

Article Description
Fuel cell systems have now reached a degree of technological maturity and appear destined to form the cornerstone of future energy technologies. But the rapid advances in fuel cell system development have left current information available only in scattered journals and Internet sites. The even faster race toward fuel cell commercialization further leaves the objectivity of many Internet articles open to question. The Fuel Cell Technology Handbook is now here to help, providing the first comprehensive treatment of both the technical and commercial aspects of high and low temperature fuel cells, fuel cell systems, fuel cell catalysis, and fuel generation. The first part of the book addresses the principles of fuel cell technology and summarizes the main concepts, developments, and remaining technical problems, particularly in fueling. The second part explores applications in automotive, stationary, and portable power generation technologies. It also provides an experts look at future developments in both the technology and its applications.With chapters contributed by experts working in academic and industrial R and D, this handbook forms a reliable, authoritative basis for understanding fuel cell technology, applications, and commercial realities. Whether youre developing fuel cell components, designing a fuel cell system, or just interested in the viability of an application, the Fuel Cell Technology Handbook is the best place to start.

Fuel cells are emerging as one of the most promising technologies, which will be supplying power to the mankind in coming times. A fuel cell is an electrochemical device that converts chemical energy of the fuel directly into electricity and heat without combustion. The concept of fuel cell was discovered long back. In the beginning of 19th century, the phenomenon of electrolysis, that is, generation of hydrogen and oxygen on passing current through water, was well known. It was in 1839 when Sir William Grove, father of the fuel cell, argued in reverse manner. When electrolysis of water (H2O) can produce H2 and O2, why not synthesis of H2 and O2 should be able to produce electricity. This argument is in same fashion, which Faraday gave before making a generator. Grove used H2 and O2 as fuel and catalysed platinum electrodes. He demonstrated that hydrogen and oxygen could produce electricity. Grove trapped the hydrogen and oxygen produced through electrolysis. These gases remained in contact with platinum electrodes. After this, Grove disconnected the battery, which fed the current for electrolysis and connected the electrodes by a wire. To his surprise, a current flowed through the wire and hydrogen and oxygen gases were gradually consumed. It showed that reverse of electrolysis was possible. He made a gas battery by connecting a number of hydrogen-oxygen cells. Ludwig Mond and Charles Langer in 1889 tried to develop a fuel cell, which had a longer life by employing a porous non-conductor container to hold the electrolyte and using coal and industrial coal gas to generate electricity using the principle of Grove, but were unsuccessful. They used expensive catalysts and for the first time used the word "fuel cell".

People all over the world tried to produce fuel cells in early 20th century unsuccessfully. It was because of lack of understanding materials and ion kinetics through electrode and electrolyte. At the same time, solid electrolytes were also tried. The scientists lost interest in this research because of continued failures and high cost. The other very important reason for not pursuing fuel cell research vigorously was discovery of other easy methods, such as diesel and petrol engines, of producing electricity. There were practically no efforts to produce electricity directly as in fuel cells. Also there were engineering difficulties to be overcome. In early 1930s, Francis T Bacon along with his colleagues started working on fuel cells. They used hydrogen and oxygen as fuel, less corrosive alkaline electrolyte and inexpensive nickel electrodes. There were technical difficulties and Bacon and his team kept on working. Finally, they demonstrated a practical 5 kW fuel cell system capable of feeding a welding machine in 1959. In October 1959, Harry Karl produced 20-horse power fuel cell. The push to develop fuel cells coincided with the development of manned space missions. Space missions required compact and reliable power source. The use of nuclear reactors, batteries and solar cells were discarded due to one or the other reason. The only alternative left was fuel cell. The National Aeronautics and Space Administration (NASA) in co-ordination with other research organisations developed fuel cells to provide power to Apollo and other manned space missions.

The success of the fuel cells in space missions led to the thinking that the fuel cells could also be the source of power on the earth. The qualities such as small size, high efficiency, low emissions etc make them attractive. Yet it was not possible to use the fuel cells as power source because of tremendously high cost. In space missions, cost may not be the consideration. Since then, there have been continuous efforts to reduce the cost to make it comparable to other existing sources. Fuel cells are now coming out of laboratories and becoming economically competitive with conventional power conversion technology. Today, fuel cell generators are providing power to many buildings and homes across the world and efforts are on further reducing the cost. The fuel cells are now being introduced in transport sector also. Most of the well-known auto manufacturers have launched prototype fuel cell powered automobiles. Fuel cells provide a range of critical benefit that no other single power technology match. When fuelled with pure hydrogen, the fuel cells produce zero emission of CO2, oxides of nitrogen and other pollutants. Even if fuelled with fossil fuels as a source of hydrogen, emission levels are lower than fossil fuels.

The efficiency of electricity generation through fuel cells is quite high when compared with conventional methods of power production as the intermediate stages of combustion and mechanical devices such as generator, turbine etc are not there at all. We require inverters for converting direct-current power, generated by fuel cells, to alternating current power before it can feed loads. The other alternative is to go for direct-current distribution, but, at present, we have mostly AC distribution. Thus fuel cells are highly efficient and dont suffer from the Carnot cycle limitations. It is possible to locate the fuel cells near the load centres and, hence, we can get rid of the transmission losses. The operating efficiency of fuel cells is independent of load. High efficiency means fuel saving and reduced CO2 emissions. Fuel cell power plants have demonstrated unprecedented reliability and durability i.e. significantly better than conventional equipment. The absence of combustion and moving parts means that the fuel cells can run continuously for long periods before servicing and are far less prone to breakdown. The hydrogen can be derived from various sources viz. natural gas and coal, renewable such as biomass, etc.
Posted : 10/26/2005

Efficiency Of Fuel Cells