Very cool, if true

I think (2) is broadly good news. The probable cost of building enough pumped hydro storage that isn't linked directly to a river system is somewhere about $40 per MWH (not sure if that was Australian or USD) which is a) not horribly expensive when you are teaming it with solar PV and wind in the 2040's and b) the most we need to pay for lots of long term storage - if batteries can do it for less, then that's better news - but the figures in that analysis ought to be the maximum.