Peaking power refers to electricity use at its highest points during a day. Day to day trends of power usage need to be met by power plants, however it is not optimal for power plants to produce the maximum needed power at all times. Therefore there are baseload power plants like coal-fired power plants which provide the minimum needed electricity, and peaking power plants which meet the fluctuating needs. Common peaking periods might include hot summer days when air conditioners are used, or cold winter days when home heating is a necessity. Most often, peaking power occurs in the afternoon when businesses are at their busiest, and evenings when home appliances are in use.
Natural gas power plants are the most common peaker power plants as they are dispatchable. This means they can be turned on or off and their output can change quite quickly. Hydroelectric facilities that use a reservoir can also be used for peaking power. For example, the Dinorwig hydro power station, located in Wales, can reach its maximum generation in less than 16 seconds.