Fuel cells in general can be categorized by various criteria such as type of fuel or operating temperature, but since this paper will be focused on hydrogen fuel cells, we will classify them according to the type of electrolyte they employ. Though other types of hydrogen fuel cells exist, the four types of fuel cells that tend to use hydrogen as their primary source of fuel (even if it is extracted from natural gas using a reformer) are: Alkaline fuel cells (AFC), Proton exchange or polymer electrolyte membrane fuel cells (PEMFC), Phosphoric acid fuel cells and Solid oxide fuel cells (SOFCs).