Definition and Citations:
Invented in 1854 by the UK physicist William Robert Grove (1811-1896). It produces energy, usually electrical, by converting a chemical substance, like hydrogen. Hydrogen flows through a porous nickel or platinum alloy cathode. The alloy splits the hydrogen into electrons and protons. The electrons pass through an external circuit. The protons pass through a liquid or membrane electrolyte, then pass into a porous carbon anode. Here oxygen is continuously introduced and the process yields water. Such a cell has an 80% efficiency, more than 2x that of any other cell. The drawback is bulk and the need of gases. Currently used in spacecraft and submarines. Exploratory automobile use is in progress.