Power generation comes in two classes, baseline and peaker. Baseline units are on 24/7. They are typically very efficient, but can take days or weeks to start. Peakers can turn on in minutes of notice and are usually better at following demand.

Power demand follows daily sinusoidal cycles. By having an economical consumer of electricity that can choose operation times, you can have them use power at night in order to flatten your sinusoidal demand, thus allowing a higher percentage of efficient baseline units to run instead of peakers.