Use of generation is often divided into three categories — baseload, which is generation run all 24 hours of the day; intermediate, which is run from mid-morning until the evening; and peaking, which is run during the peak hours (often from late afternoon until early evening).
Peaking generation is most commonly provided by single-cycle gas turbines (also known as combustion turbines or peaking turbines), gas reciprocating engines, hydropower, pumped hydro, battery storage, and economic demand response. Peaking units must have operational flexibility to be able to ramp up or down quickly in response to load changes and to be able to turn on and off as loads change.