Boysen et al. report acid fuel cells with higher performance through humidity stabilization in Science (2004), 303(5654): 68-70. Fuel cells are a possible solution for use in transportation, and involve an electrochemical reaction, which resembles the way a battery works. The difference between a fuel cell and a battery is that a battery can store energy internally, whereas a fuel cell needs a supply of reactant to keep it running. The fuel provided to the cell has its electrons and protons separated by catalysis, and the electrons then travel through a circuit, which converts them into electrical energy. There are many many different types of fuel cells, which use many different forms of catalysts.
Acid fuel cells are desirable because the heat generated by these fuels cells can be used in part to continue reactions, which makes the reactions more efficient and allows the radiator in cars to be smaller. Also, acid fuel cells do not require precise water supply measurements and worries because their reaction is anhydrous (this is not the case for polymer fuel cells). However, attempts at making fuel cells from acids (specifically superprotonic solid acids) has been difficult due to their solubility in water and their “poor mechanical behavior.” However, researchers have found that operating the fuel cells at over 100 degrees C has reduced these issues.
Water (or humidity, because water ceases to be in its liquid form at the temperatures it is being used at) is used to stabilize the reactions of the solid acid fuel cells, making them more efficient and more reliable.