Water is freely available. In the examples mentioned, there's typically a natural reservoir (a lake) or man-made reservoir (a retention pond) that's used. You m

Water is freely available. In the examples mentioned, there's typically a natural reservoir (a lake) or man-made reservoir (a retention pond) that's used. You might get a slight boost from using sea water (density of 1027 vs 1000), but I feel like the salinity might wear your equipment faster. Also, heavy metals like mercury and iodine very are expensive compared to water. And once you start talking about using metals for storage, it might be worth exploiting state changes instead.[0] [0]: http://www.ambri.com/ http://www.ambri.com/