With traditional fossil fuels, you would just lower power production when demand is low. The need for large scale storage really arises from renewables like sol

With traditional fossil fuels, you would just lower power production when demand is low. The need for large scale storage really arises from renewables like solar where you might get plenty of power over the course of the day, but there are going to be extended periods (namely night) where it doesn't matter how much excess capacity you have, you're not generating power.