This article attempts to list pseudoscientific inventions wherein common water is used to either augment or generate a fuel to power an engine, boiler or other source of power.
This is not to be confused with legitimate inventions (such as hydroelectricity) in which the kinetic energy of flowing water is used for power.
Nonetheless, several people have claimed to create devices that do exactly this.
Ruggero Maria Santilli's "Magnegas" recyclers, which use an underwater carbon arc to gasify bio-contaminated liquid into a clean-burning gas.
[7] Water is claimed to be transformed into a fuel itself, by the addition of some ingredient.