OK how this works is the water is directly injected into the expansion space formed by the piston and cylinder. Almost like a high pressure modern diesel direct injection system... actually operates at similar pressures of around 7000 Bar. The water flashes to steam on impact with a hard surface in the cylinder, cylinder head or piston crown made of something like polycrystalline diamond. Therefore, the steam is produced on injection of the water steam. The issue is the pumps that produce the pressure put the energy into the water in compression like any hydraulic fluid... and this is little different from heating water to create steam... but it is heat energy (powering pumps though creation of either the electrical or mechanical energy) that is converted to hydraulic energy as both pressure and flow. So just guessing without doing a very complex energy balance its not much better than heating the water and creating steam in the first place... likely worse: This means less energy efficient or higher ultimate entropy of the whole system. Why is all the energy change interfaces chemical > heat > kinetic (steam) > electric > Kinetic (hydraulic) > heat > kinetic (steam) > kinetic (mechanical). At every stage of interface or change from one form to another there is energy that cannot be tapped and turned into useful work in the exchange (entropy)... but there are two phase changes both taking place in the piston cylinder water to steam and then back steam to water. See on a steam engine it works boiler chemical > heat > kinetic (steam) > (kinetic) mechanical. There are two phase changes first water to steam and then steam to water. Therefore, in the lab if the energy comes from the electric power company to the water or give it hydraulic energy is free it really works but put it in a closed cycle and I doubt it adds up any better than a conventional boiler supplied steam system.... just a bunch of different equipment... all just to not have to have a boiler???