You can use pumped hydro to address two different, but related problems: a) What to do with excess power at any given time. b) How to address production short

You can use pumped hydro to address two different, but related problems: a) What to do with excess power at any given time. b) How to address production shortfall at any given time. Idle industrial capacity only addresses how to extract value from a), but doesn't really address b (except indirectly by giving you some incentive to just really overbuild your capacity). So from a system standpoint, the idle capacity approach doesn't just have the extra capital cost of your industrial plants, you also have the capital cost to build out your generation capacity even more.