The water fuel cell is a technical design of a "perpetual motion machine" created by American Stanley Allen Meyer (August 24, 1940 – March 20, 1998), around which a case of controversy developed. He claimed that an automobile 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.
The fuel cell purportedly split water into its component elements, hydrogen and oxygen. The hydrogen was then burned to generate energy, a process that reconstituted the water molecules. According to Meyer, the device required less energy to perform electrolysis than the minimum energy requirement predicted or measured by conventional science. The mechanism of action was alleged to involve "Brown's gas", a mixture of oxyhydrogen with a ratio of 2:1, the same composition as liquid water. If the device worked as specified, it would violate both the first and second laws of thermodynamics, allowing operation as a perpetual motion machine.