This makes a good deal of sense for plants that have considerable ramp up costs during times of off-peak demand. I worked at a biomass plant once where it took

This makes a good deal of sense for plants that have considerable ramp up costs during times of off-peak demand. I worked at a biomass plant once where it took hours to go from cold to get the boiler fired and get steam pressure up. They cut back production when power prices were low or negative, but they had to run at a minimum capacity all the time because they couldn't just stop and start on a dime.