That is utterly nonsensical. Are there HUGE tracts of land where 100 ton railcars or concrete blocks grow on trees?
If not, then how are you getting them there? On a per-mass basis what do you think is easier to transport, railcars or water?
Transporting adequate amounts of gravity storage medium is not at all a competitive advantage for non-hydro gravity storage. For that matter, it does not even constitute a meaningful factor except as a disqualifying one for the nonsensical ideas people somehow seem to get funded.
I'm not totally sold on the idea itself, but... you don't need to get a 100 ton railcar there. Ship empty railcars and fill it with rocks / sand / water or whatever you find at the destination.
If not, then how are you getting them there? On a per-mass basis what do you think is easier to transport, railcars or water?
Transporting adequate amounts of gravity storage medium is not at all a competitive advantage for non-hydro gravity storage. For that matter, it does not even constitute a meaningful factor except as a disqualifying one for the nonsensical ideas people somehow seem to get funded.