His entry in the Dyson Student Design competition in Australia was a fuel-cell-powered steam mop for home use. He calls it the Hydrop. The hydrogen fuel cell not only generates electricity to heat the water into steam, it makes the water as well. And as long as it has hydrogen for fuel, the cordless appliance will never run out of water. (But homeowners will have to find a source of hydrogen to refill the fuel tank.)

Fuel cell