I would read Tom Murphy's posts from a different light. His message has consistently been 'unbounded exponentials aren't real, why are you pretending they are?'

I would read Tom Murphy's posts from a different light. His message has consistently been 'unbounded exponentials aren't real, why are you pretending they are?'. In that light 'pumped hydro can't scale' means 'stop trying to use this for Petawatt hours of energy storage you idiot, you'll destroy everything'. Some of his more recent posts have been worryingly easy to coopt by the 'maek moar fossil fuels and nuclear' crowd, which his previous posts indicate he should be even more strongly opposed to. The general message of degrowth and steady state economy is positive even if 'pumped hydro can't scale indefinitely' sounds a bit like 'pumped hydro can't decarbonize the current scale of the economy', and he gets the scale required to maintain status quo consumption a bit wrong. I do wish he'd make this distinction clearer though.