Base load

The base load (also baseload) is the minimum level of demand on an electrical grid over a span of time, for example, one week. This demand can be met by unvarying power plants, dispatchable generation, or by a collection of smaller intermittent energy sources, depending on which approach has the best mix of cost, availability and reliability in any particular market. The remainder of demand, varying throughout a day, is met by dispatchable generation which can be turned up or down quickly, such as load following power plants, peaking power plants, or energy storage.

Power plants that do not change their power output quickly, such as large coal or nuclear plants, are generally called baseload power plants. Historically, most or all of base load demand was met with baseload power plants, whereas new capacity based around renewables often employs flexible generation.