Alkaline Fuel Cell (AFC) Engineering Design, Modeling and Simulation for UPS Provide in Laboratory Application

Abstract

P roton exchange membrane fuel cells (PEMFCs) are currently capable of providing power for a variety of applications, ranging from automotive transportation to portable electronics to military devices. The widespread commercialization of PEMFCs, however, remains a challenge due to cost, lifetime, and fueling issues. 1,2 The need for precious metal catalyst electrodes in PEMFCs is of concern because of uncertainties regarding the future availability and price of platinum group metals (PGMs), should PEM fuel cells see widespread use. It is not at all certain that that there is enough Pt in the world today to sustain a sizable fraction of autos in the U.S. being powered by PEMFCs. Anion exchange membrane fuel cells (AEMFCs) are, in principle, a viable alternative to PEMFCs and are currently garnering renewed attention. In an AEMFC, an anion exchange membrane (AEM) conducts hydroxide (or carbonate) anions (as opposed to protons) during current flow, which results in several advantages. (1.) The oxygen reduction reaction (ORR) is much more facile in alkaline environments than in acidic environments. 3 This could potentially facilitate the use of less expensive non-PGM catalysts with high stability in alkaline environments. (2.) The electro-oxidation kinetics for many liquid fuels (including non-conventional choices of importance to the military, such as sodium borohydride) are enhanced in an alkaline environment. (3.) The electro-osmotic drag associated with ion transport opposes the crossover of liquid fuel in AEMFCs, thereby permitting the use of more concentrated liquid fuels. This is an advantage for portable applications. (4.) The flexibility in terms of fuel and ORR catalyst choice also expands the parameter space for the discovery of highly selective catalysts that are tolerant to crossover fuel. These potential advantages make AEMFCs an attractive future proposition. Alkaline fuel cells were first developed in the 1930s by F. T. Bacon, thus they pre-date PEM fuel cells and represent one of the oldest fuel cell types. Early alkaline fuel cells operated with H 2 as the fuel at a temperature between 50 and 200 o