Alkaline fuel cell

From ArticleWorld

One of the most evolved fuel cell technologies is the Alkaline fuel cell (often referred to as simply AFC). It is the one that was used for the space rockets that landed on the moon during the Lunar Expeditions. NASA used it to fuel the Apollo Missions and their use dates back to the mid sixties. The Alkaline fuel cell works by consuming hydrogen quantities and oxygen. It produces what is called pure water, heat and even electricity. The AFC is the only fuel cell that can reach 70%.

Production

The Alkaline fuel cell is based on a redox reaction between Oxygen and Hydrogen. At the anode part of the cell the reaction between 2 molecules of Hydrogen and 4 of hydroxide will result in 4 molecules of water and 4 electrons that are used for power. The ending result is actually 2 electrons that will follow a strict circuit to return to the cathode. There oxygen is reduced and hydroxide ions are produced. Two byproducts of the two reactions are heat and electricity. Between the two electrodes a special saturated by an aqueous alkaline solution porous matrix can be found. In most cases that solution is potassium hydroxide. The only problem is that the system needs pure oxygen or at least a pure air composition. This translates in the fact that an AFC system is very expensive to build and has even made NASA switch to Proton-exchange fuel cells. They will be used in the next space shuttles that are in project to be built. On the other hand, the Alkaline fuel cell is cheap to build because of the many possibilities of cathode substances that can be used. This makes it difficult to decide weather to use it or not, based on how much it needs to be used.