Engineering-wise, he's got good arguments. Though maybe he should talk to some civil engineers, about all the ways in which large reservoirs can go horribly wrong. Especially if you're cycling them between empty and full every day. (Plus, it looks like the ANU study that he cites did <i>not</i> exclude seismically active areas from their map of potential pumped hydro locations.)<p>Socially...I'm not so sure. Pumped hydro can have serious NIMBY problems. And my sense is that 99% of pro-energy-storage voters are actually motivated by performative storage. Not by sane-at-scale working solutions.