Fuel cell
Proton Exchange Membrane fuel cell (PEM) - These fuel cells operate at relatively low temperatures (about 175 °F), have high power density, can vary their output quickly to meet shifts in power demand, and are suited for applications, such as in automobiles, where quick startup is required. All commercial fuel cell vehicles use this type of fuel cell. The drawback of these fuel cells is that they require high-purity hydrogen which is costly to produce.