Dispatchable generation

Dispatchable generation refers to sources of electricity that can be used on demand and dispatched at the request of power grid operators, according to market needs. Dispatchable generators can be turned on or off, or can adjust their power output according to an order. This is in contrast with non-dispatchable renewable energy sources such as wind power and solar PV power which cannot be controlled by operators. The only types of renewable energy that are dispatchable without separate energy storage are hydroelectric, biomass, geothermal and ocean thermal energy conversion. Dispatchable generation refers to sources of electricity that can be used on demand and dispatched at the request of power grid operators, according to market needs. Dispatchable generators can be turned on or off, or can adjust their power output according to an order. This is in contrast with non-dispatchable renewable energy sources such as wind power and solar PV power which cannot be controlled by operators. The only types of renewable energy that are dispatchable without separate energy storage are hydroelectric, biomass, geothermal and ocean thermal energy conversion. Dispatchable plants have different speed at which they can be dispatched.The fastest plants to dispatch are hydroelectric power plants and natural gas power plants. For example, the 1,728 MW Dinorwig pumped storage power plant can reach full output in 16 seconds.Although theoretically dispatchable, certain thermal plants such as nuclear or coal are designed to run as base load power plants and may take hours or sometimes days to cycle off and then back on again. The attractiveness of utility-scale energy storage is that it can compensate for the indeterminacy of wind power and solar PV power. During 2017, solar thermal storage power has become cheaper and a bulk dispatchable source. Earlier, affordable large-scale storage technologies other than hydro were not available. The main reasons why dispatchable power plants are needed are: