According to the Washington Post, older, less efficient power plants can be retired if energy demand is spread out during the day.
There are peak hours in a day when energy demand spikes, for example, the hours after work when people go home and turn on their televisions and air conditioning systems. During the peak times, intermediate plants that are expensive to operate and consume fuel inefficiently are brought onto the grid because they turn on or off quickly. Solutions include installing smart meters or emailing reminders to consumers directly to help regulate personal energy consumption.
