Yes but centrifugal forces on the simle “rotating fluid” equivalent are too strong and require a costly casing when compared to an equivalent solid flywheel. Wh

Yes but centrifugal forces on the simle “rotating fluid” equivalent are too strong and require a costly casing when compared to an equivalent solid flywheel. What they do is they use the rotating part as a pump to push the fluid up a vertical pressurized storage and the pressure there plus the potential energy of the fluid store the energy in a more manageable matter than having it all in the fluid speed