Alkaline Fuel Cells

There are a wide range of assortments of fuel cells in addition to the hydrogen PEM fuel cell. They are classified based on the type of materials used for the electrolyte, the type of fuel utilized, or common operation temperature [7].

There are seven primary types of fuel cell of commercial importance: Alkaline Fuel Cell (AFC), Proton Exchange Membrane Fuel Cell (PEMFC), Direct Methanol Fuel Cell (DMFC), Phosphoric Acid Fuel Cell (PAFC), Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC) and Biofuel Cells.

5.1 Alkaline Fuel Cell (AFC)

Hydrogen is used as the fuel in alkaline fuel cells; however, rather than protons, hydroxyl ions serve as the mobile ions in an alkaline electrolyte, most commonly potassium hydroxide. The anode

Non- valuable metal catalysts can also be used making these fuel cells very low in cost [8, 9]. Despite of these advantages, NASA and many of the fuel cell worlds started moving from alkaline fuel cells in favor of PEM-based technology in the 1970s and 1980s, and today they get far less research and development attention

The option, which is to utilize methanol as a fuel and utilize a reformer, is both expensive and fraught with engineering difficulties.

Highly desirable would be a fuel cell that could directly oxidize methanol at the anode, but maintain the high power/weight ratio of the SPE fuel cell described previously. Such a fuel cell is presently under active development in Europe and the USA, and the principles are shown in Figure 6. The anode reaction is

〖CH〗_3 OH+H_2 O →〖CO〗_2+6H^++6e^- (5.2) and the cathode reaction is

3/2 O_2+6H^++6e^- →〖3H〗_2 O (5.3)

Methanol has a lot of advantages as a fuel: it is a liquid, and therefore easily transported and stored and dispensed within the current fuel network; it is cheap and abundant, and the only products of combustion are 〖CO〗_2 and H_2 O. The benefits of a direct methanol fuel cell are: changes in power demand can be suited just by modification in supply of the methanol feed; the fuel cell works at temperatures below ca. 150 C so there is no production of 〖NO〗_X, methanol is stable in contact with the acidic membrane, and is easy to