spinningsreserve

Spinningsreserve is not a widely used term in formal energy literature, and the concatenated form is rarely seen. In most sources, the concept is called spinning reserve. Spinning reserve refers to online generating capacity that can respond quickly to disturbances and help maintain system reliability in an electric power grid.

Spinning reserve is the portion of generation that is already online and operating, but not loaded to its maximum output. When a disturbance occurs—such as the sudden loss of a generator or a sharp spike in demand—the spinning reserve can increase its output to restore balance between generation and consumption. This fast-ramping capability helps stabilize grid frequency and prevent outages. Typical response times range from seconds to several minutes, depending on the technology and system rules.

The capacity for spinning reserve is planned and scheduled by the grid operator. It is commonly funded or counted as part of the operating reserve requirements and is measured in megawatts (MW) or as a percentage of forecasted peak demand. Sources of spinning reserve include fast-ramping fossil-fueled plants (such as gas turbines), hydro units, pumped-storage facilities, and, increasingly, battery storage systems. Some markets also use demand response or minor generation startups to supplement online reserves.

Regulatory and market frameworks define the exact requirements for spinning reserve, including the amount of reserve to hold, response time, and how it is activated. As grids integrate more intermittent generation from wind and solar, the role and composition of spinning reserve can evolve, with storage and flexible resources playing a growing part in maintaining reliability.