The point, also, is to put it out in the desert, near all those utility-scale solar plants, where there's no water for pumped storage to soak up daytime over-production and feed it back in the evening or at night when it's needed (and most profitable). Still not practical to do utility-scale storage with batteries - getting there, but not there yet. The crazy train is a very-small-scale version of pumped storage that doesn't require water to run - so good for use in the desert. I wonder if it'll produce as much as planned, though ... in principle it works in practice, but maybe not in practice? Can't tell for sure without trying one, though.