dispatchable

Dispatchable refers to a power source or supply that can be scheduled and controlled by a grid operator to meet electricity demand. A dispatchable resource can be turned on or off and adjusted up or down within its technical limits, allowing it to follow the system load and provide reliable service. The degree of dispatchability depends on technology, fuel, and plant design. The term is used in other contexts to describe assets that can be commanded or scheduled; in electricity, it refers to generation or storage that can be controlled by a grid operator.

Common dispatchable resources include fossil-fuel-fired generators such as natural gas and coal plants, certain nuclear plants that participate in load-following, and hydroelectric plants with controllable reservoirs. Pumped-storage hydro and other forms of energy storage add dispatchability by delivering power when needed. Some gas turbines can rapidly ramp and provide fast frequency response, enhancing flexibility. Geothermal plants are often dispatchable but limited by resource temperature and capacity.

Non-dispatchable or variable resources, such as most wind and solar projects, generate based on resource availability and are not easily scheduled to match demand. Grid operators balance these resources with dispatchable output, demand response, imports, and storage. Dispatchable capacity is critical for reliability, enabling ramping to meet sudden demand changes and to replace intermittent generation during low-resource periods. Nevertheless, dispatchable generation incurs operating costs and, in some cases, higher emissions, depending on the technology. The concept of dispatchability is central to discussions of grid reliability, capacity markets, and the integration of renewable energy.