Tidal Assist
Hmmm just thinking about this - if you pumped out all the water at low tide, then waited until high tide to start your turbines then you could actually get out significantly more electricty than you had pumped in - the difference coming from tidal energy. Then at low tide open a flood gate and just let the excess water pour out - same approach as a tidal barrage.........so this could actually be more efficient than just pumped storage and might actually produce more energy than had been taken from the grid..the problem is of course that may not fit the spot market/ demand profile. However, at least tides are nice and predictable so you can take advantage of them some of the time.