A water-fuelled car is an automobile that hypothetically derives its energy directly from water. Water-fuelled cars have been the subject of numerous international patents, newspaper and popular science magazine articles, local television news coverage, and websites. The claims for these devices have been found to be pseudoscience and some were found to be tied to investment frauds. These vehicles may be claimed to produce fuel from water on board with no other energy input, or may be a hybrid claiming to derive some of its energy from water in addition to a conventional source (such as gasoline).
Water is fully oxidized hydrogen. Hydrogen itself is a high-energy, flammable substance, but its useful energy is released when water is formed. Water will not burn. The process of electrolysis can split water into hydrogen and oxygen, but it takes as much energy to take apart a water molecule as was released when the hydrogen was oxidized to form water. In fact, some energy would be lost in converting water to hydrogen and then burning the hydrogen because some waste heat would always be produced in the conversions. Releasing chemical energy from water, in excess or in equal proportion to the energy required to facilitate such production, would therefore violate the first or second law of thermodynamics.
The hydrogen car, although it often incorporates some of the same elements. To fuel a hydrogen car from water, electricity is used to generate hydrogen by electrolysis. The resulting hydrogen is an energy carrier that can power a car by reacting with oxygen from the air to create water, either through burning in a combustion engine or catalyzed to produce electricity in a fuel cell.
Charles H. Garrett allegedly demonstrated a water-fuelled car “for several minutes”, which was reported on September 8, 1935, in The Dallas Morning News. The car generated hydrogen by electrolysis as can be seen by examining Garrett’s patent, issued that same year. This patent includes drawings which show a carburetor similar to an ordinary float-type carburetor but with electrolysis plates in the lower portion, and where the float is used to maintain the level of the water. Garrett’s patent fails to identify a new source of energy.