The amount of time for a generation unit to reach a targeted level of production capacity.
In context of electricity: The capability of a generating unit to automatically respond to the CAISO’s four-second automatic generation control signal to adjust its output as may be needed to maintain system frequency and reduce risks of outages. [Source: California Independent System Operator (CAISO), 2013 Flexible Capacity Procurement Requirements, p.9.]
Deploying and operating enough flexible, controllable resources to ensure grid reliability given the variability and uncertainty associated with intermittent renewable power generation. [Source: California Energy Commission (CEC) Website: http://www.cpuc.ca.gov/PUC/energy/Renewables/hot/Renewable+Integration.htm]
Power generation capacity used to serve peak demand. Peaking generating units operate a limited number of hours per year, and their capacity factor is normally less than 20%. Peaking capacity is often served by simple cycle combustion turbines. [Source: The Potential Benefits of Distributed Generation and Rate-Related Issues That May Impede Their Expansion, U.S. Department of