412types Of Fuel Cell

Fuel cells are described by their electrolyte:

Alkaline - AFC Phosphoric acid - PAFC

Solid Polymer - SPFC (also referred to as proton exchange membrane - PEMFC) Molten carbonate - MCFC Solid oxide - SOFC.

Hydrogen -

Unreacted Hydrogen

Oxygen (air)

Water

Oxygen (air)

Water

Single cell -1V

Fig. 4.1 Basic chemical reactions in a fuel cell.

The reaction shown in Fig. 4.1, with hydrogen ion transfer through the electrolyte, is only applicable to fuel cells with acid electrolytes and solid polymer fuel cells. The reactions in each of the fuel cell types currently under development1 are:

Cell

Anode

Cathode

AFC PAFC SPFC MCFC

SOFC

4.1.3 HISTORY

The concept of the fuel cell was first published in 1839 by Sir William Grove when he was working on electrolysis in a sulphuric acid cell. He noted a passage of current when one platinum electrode was in contact with hydrogen and the other in contact with oxygen. In 1842 he described experiments with a stack of 50 cells, each with one quarter of an inch wide platinized platinum electrodes and he noted the need for a 'notable surface of action' between the gases, electrolyte and electrodes. Over the next 90 years a number of workers published papers on both acid and alkali fuel cells, including the development of three dimensional electrodes by Mond and Langer in 1889. But it was not until 1933, when F. T. (Tom) Bacon (an engineer with the turbine manufacturers C. A. Parsons & Co. Ltd.) started work with potassium hydroxide as the electrolyte and operating at 200°C and 45 atm, that significant progress was made. The main thrust for development of fuel cells was the space programme of the early 1960s, when NASA placed over 200 contracts to study and develop fuel cells. The first major application was the use of solid polymer fuel cells developed by General Electric for on-board power in the Gemini programme. By 1960 Bacon had transferred to the Pratt and Whitney Division of United Aircraft Corporation (now United Technologies Corporation) in the USA, and led the development of the on-board power system for the Apollo lunar missions. Ninety-two systems were delivered and 54 had been used to power nine moon shots by 1965. This was followed by UTC's development of a 7 kW stack which is used in the Space Shuttle. During the 1990s fuel-cell development accelerated, with particular interest in automotive and small distributed power systems as the main target applications2"3,7.

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