Fuel cell
From ArticleWorld
A fuel cell is a device in which energy obtained from a chemical reaction is directly converted into electrical energy. It differs from an ordinary battery in that it does not exhaust itself; it has to be continuously supplied by ‘fuel’. The reactants required are continuously available from outside. Fuel cells have already been implemented in vehicles by a number of companies.
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Constituents of a fuel cell
A fuel cell essentially consists of an anode which is the positive electrode of an electric circuit and a cathode which is the negative electrode. Both electrodes are made of carbon paper coated with platinum as a catalyst. The two are separated by an electrolytic solution, which lets positive or negative ions to flow in them. The fuel ions flow towards the anode, while the oxidant flows towards the cathode. The device works as long as the fuel and oxidant supplies are maintained from outside.
How it works
The production of electricity in a fuel cell depends on the chemical reaction between the fuel and the oxidant. A number of fuels have been experimented with, but most research has been concentrated on the use of hydrogen as fuel. In a hydrogen fuel cell, known as proton-exchange membrane fuel cell (PEMFC), the anode receives the fuel while the cathode receives the oxidant, which is oxygen. As electrons are removed from hydrogen atoms, they move from the anode towards the cathode, giving rise to an electric current. This is how power can be provided. The electron-deprived atoms of hydrogen reach the cathode, where they combine with oxygen atoms forming water, the only ‘waste’ product.
While oxygen is readily available in air, hydrogen has to be continuously supplied. Production of hydrogen is expensive and may necessitate the burning of fossil fuels for the purpose. Fuel cell technology can be said to be completely environment-friendly if non-polluting energy sources are utilized to yield hydrogen. The content of water should be optimum; neither too less so as to hamper flow of electrons across the proton membrane nor too much so as to flood the electrodes.
Applications
Fuel cells are used in a wide variety of applications. Since they require fuel from outside, they can easily be implemented in places where large scale energy storage is necessary. Fuel cells are an excellent example of co-generation being used; both generation of electricity and water/space heating can be carried out in a process called combined heat and power (CHP). Moreover, any systems using fuel cells running on hydrogen are light in weight and very convenient to deal with. This makes them an excellent choice for remote weather monitoring stations, military bases and even spacecraft.
Fuel cell vehicles have been manufactured by a number of companies like General Motors (GM), Toyota, Ford and Diamler Chrysler. The prices of these cars are still prohibitively high, but with ongoing research to reduce the requirement of platinum as catalyst, they may enter the market soon.
History and development of fuel cells
The principle of fuel cells was first identified in 1838 by Christian Schonbein, a Swiss scientist. A few important experiments were made after that but it was only in 1959 that a major breakthrough was made, when Francis Bacon succeeded in making a 5KW fuel cell. Most fuel cells now have an efficiency of 50%. The remaining energy can be used for heating purposes, making it useful as a cogeneration unit.
Fuel cells were manufactured for the first time by the company United Technologies in the USA. NASA has been using their fuel cells for its Apollo missions and space shuttles. Military, industrial and consumer applications are on the increase.
During the last two decades, significant technological advancements have been made in this direction. Today, major car-makers are developing ways to make fuel cell cars less expensive.