[cperciva]

The idea there isn't that you store power but rather that you only run the plant when power is cheap (and then keep a large enough fresh water reservoir to serve demand until the next cheap electricity arrives). Demand management rather than supply management, effectively.

[nl]

Yeah, the problem is that it's not easy to store very large amounts of water (at least not near where the Adelaide Desalination plant is).

I believe they can pump the water up into the hill, so I guess it's not entirely out of the question.