The water fuel cell is a non-functional design for a "perpetual motion machine" created by Stanley Allen Meyer (August 24, 1940 – March 20, 1998). Meyer claimed that a car retrofitted with the device could use water as fuel instead of gasoline. Meyer's claims about his "Water Fuel Cell" and the car that it powered were found to be fraudulent by an Ohio court in 1996. Purported design. The water fuel cell purportedly split water into its component elements, hydrogen and oxygen. The hydrogen gas was then burned to generate energy, a process that reconstituted the water molecules.
https://en.wikipedia.org/wiki/Water_fuel_cell