23 June 2009

Fuel cell

The invention: An electrochemical cell that directly converts energy from reactions between oxidants and fuels, such as liquid hydrogen, into electrical energy. The people behind the invention: Francis Thomas Bacon (1904-1992), an English engineer Sir William Robert Grove (1811-1896), an English inventor Georges Leclanché (1839-1882), a French engineer Alessandro Volta (1745-1827), an Italian physicist The Earth’s Resources Because of the earth’s rapidly increasing population and the dwindling of fossil fuels (natural gas, coal, and petroleum), there is a need to design and develop new ways to obtain energy and to encourage its intelligent use. The burning of fossil fuels to create energy causes a slow buildup of carbon dioxide in the atmosphere, creating pollution that poses many problems for all forms of life on this planet. Chemical and electrical studies can be combined to create electrochemical processes that yield clean energy. Because of their very high rate of efficiency and their nonpolluting nature, fuel cells may provide the solution to the problem of finding sufficient energy sources for humans. The simple reaction of hydrogen and oxygen to form water in such a cell can provide an enormous amount of clean (nonpolluting) energy. Moreover, hydrogen and oxygen are readily available. Studies by Alessandro Volta, Georges Leclanché, and William Grove preceded the work of Bacon in the development of the fuel cell. Bacon became interested in the idea of a hydrogen-oxygen fuel cell in about 1932. His original intent was to develop a fuel cell that could be used in commercial applications. The Fuel Cell Emerges In 1800, the Italian physicist Alessandro Volta experimented with solutions of chemicals and metals that were able to conduct electricity. He found that two pieces of metal and such a solution could be arranged in such a way as to produce an electric current. His creation was the first electrochemical battery, a device that produced energy from a chemical reaction. Studies in this area were continued by various people, and in the late nineteenth century, Georges Leclanché invented the dry cell battery, which is now commonly used. The work of William Grove followed that of Leclanché. His first significant contribution was the Grove cell, an improved form of the cells described above, which became very popular. Grove experimented with various forms of batteries and eventually invented the “gas battery,” which was actually the earliest fuel cell. It is worth noting that his design incorporated separate test tubes of hydrogen and oxygen, which he placed over strips of platinum. After studying the design of Grove’s fuel cell, Bacon decided that, for practical purposes, the use of platinum and other precious metals should be avoided. By 1939, he had constructed a cell in which nickel replaced the platinum used. The theory behind the fuel cell can be described in the following way. If a mixture of hydrogen and oxygen is ignited, energy is released in the form of a violent explosion. In a fuel cell, however, the reaction takes place in a controlled manner. Electrons lost by the hydrogen gas flow out of the fuel cell and return to be taken up by the oxygen in the cell. The electron flow provides electricity to any device that is connected to the fuel cell, and the water that the fuel cell produces can be purified and used for drinking. Bacon’s studies were interrupted byWorldWar II. After the war was over, however, Bacon continued his work. Sir Eric Keightley Rideal of Cambridge University in England supported Bacon’s studies; later, others followed suit. In January, 1954, Bacon wrote an article entitled “Research into the Properties of the Hydrogen/ Oxygen Fuel Cell” for a British journal. He was surprised at the speed with which news of the article spread throughout the scientific world, particularly in the United States. After a series of setbacks, Bacon demonstrated a forty-cell unit that had increased power. This advance showed that the fuel cell was not merely an interesting toy; it had the capacity to do useful work. At this point, the General Electric Company (GE), an American corporation, sent a representative to England to offer employment in the United States to senior members of Bacon’s staff. Three scientists accepted the offer. A high point in Bacon’s career was the announcement that the American Pratt and Whitney Aircraft company had obtained an order to build fuel cells for the Apollo project, which ultimately put two men on the Moon in 1969. Toward the end of his career in 1978, Bacon hoped that commercial applications for his fuel cells would be found.Impact Because they are lighter and more efficient than batteries, fuel cells have proved to be useful in the space program. Beginning with the Gemini 5 spacecraft, alkaline fuel cells (in which a water solution of potassium hydroxide, a basic, or alkaline, chemical, is placed) have been used for more than ten thousand hours in space. The fuel cells used aboard the space shuttle deliver the same amount of power as batteries weighing ten times as much. On a typical seven-day mission, the shuttle’s fuel cells consume 680 kilograms (1,500 pounds) of hydrogen and generate 719 liters (190 gallons) of water that can be used for drinking. Major technical and economic problems must be overcome in order to design fuel cells for practical applications, but some important advancements have been made.Afew test vehicles that use fuel cells as a source of power have been constructed. Fuel cells using hydrogen as a fuel and oxygen to burn the fuel have been used in a van built by General Motors Corporation. Thirty-two fuel cells are installed below the floorboards, and tanks of liquid oxygen are carried in the back of the van. A power plant built in New York City contains stacks of hydrogen-oxygen fuel cells, which can be put on line quickly in response to power needs. The Sanyo Electric Company has developed an electric car that is partially powered by a fuel cell. These tremendous technical advances are the result of the singleminded dedication of Francis Thomas Bacon, who struggled all of his life with an experiment he was convinced would be successful.

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