Make a water-powered generator, but market it as a regular generator that needs to be topped off with water for "cooling". Do all this under an alias and leave the county once people catch on and repeat in another country. Eventually the tech will be everywhere and they can't stop it.

Ignoring for a moment every other problem with this that people are clowning you for, such as the laws of thermodynamics, I'm gonna play along to get at another angle.... What would you be telling people is the fuel source? If you're telling people that the water is coolant than you seem to want people under the impression that this thing gets hot and needs coolant and also that it has some type of fuel source that isn't the water. Would people not immediately want to know what fuel to use with? If you tell people that this generator doesn't use any fuel they're not gonna buy because obviously you can't generate energy from nothing.