Dispatchable generation refers to sources of electricity that can be dispatched at the request of power grid operators; that is, generating plants that can be turned on or off, or can adjust their power output on demand. This should be contrasted with certain types of base load generation capacity, such as nuclear power

Nuclear power

Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, which may have limited capability to maneuver or adjust their power output, or intermittent power sources such as wind power

Wind power

Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships....

which cannot be controlled by operators. The time periods in which dispatchable generation plant may be turned on or off may vary, and be considered in time frames of minutes or hours.

The attractiveness of utility-scale energy storage is that it can compensate for the intermittency of wind power and solar power. However in practice, large-scale storage technologies other than pumped hydro remain in an early stage of development and are expensive.