Hydrogen production by water electrolysis

An electrolyzer combines an oxidation and a reduction reaction, driven by electricity, to produce separate streams of hydrogen gas and oxygen gas by a process called electrolysis. The hydrogen contains a portion of the electrical energy, and it can be used to generate electricity in a fuel cell by a process that is the reverse of electrolysis. If water electrolysis is driven by renewable electricity, it can be used in fuel-cell electric vehicles to displace petroleum, increase vehicle efficiency, and reduce the environmental impact of vehicles. The fundamental aspects of electrolytic hydrogen and its use as energy carrier are discussed.