You would think so, but not really, because you still have to pay for the hardware but then you're only using it a small fraction of the time.

Where it works well is in the opposite direction: You buy the hardware and use it 90%+ of the time but shut it down during a supply shortfall. Then you're making good use of the hardware and helping to amortize the cost of additional generation capacity but save the grid from running out of power in an emergency.