Have been familiar with hydrogen engines. If water splitters have been functionally developed and H2O separation rates in terms of milliseconds have been advanced, close-loop cycle Hydrogen engines is not far from reality.Splitting pure H2O into Hydrogen and Oxygen,liquify them and combining them to produce high-pressure steam to produce shaft power, condense the steam to liquid water again. Then the cycles repeats again. Its a close-loop cycle. H2O=H2+O2;O2+H2=H2O. Imagine the vast source of the most common liquid on the face the planet(earth).