Dispatchable generation

Dispatchable generation refers to sources of electricity that can be dispatched at the request of power grid operators or of the plant owner; that is, generating plants that can be turned on or off, or can adjust their power output accordingly to an order. Often base load power plants such as nuclear or coal cannot be turned on and off in less than several hours. 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 1,728 MW Dinorwig pumped power station can reach full output in 16 seconds.

This may be contrasted with intermittent renewable energy sources such as wind power and solar power which cannot be controlled by operators.

The most common dispatchable power plant is natural gas. The only types of renewable energy which are dispatchable are biofuel, biomass, hydropower with a reservoir, ocean thermal energy conversion and concentrated solar power with thermal storage.

The main reasons for which dispatchable power plants are needed are: - to balance electrical system (load following, frequency control) - to optimize generation dispatch (merit order) - to provide requested power spinning reserves - to contribute to clear grid congestions/constraints -

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.

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