Reservekraft

Reservekraft, or reserve power, is the generation capacity kept in reserve to ensure the reliability and balance of an electric power system. It is mobilized when there is a shortfall between available generation and demand, when a generation unit trips offline, or when there are unexpected fluctuations in net load. Reservekraft serves as a safeguard against outages and helps maintain system frequency and stability.

There are several types of reservekraft. Spinning reserve consists of online generation that can increase output within minutes. Non-spinning reserve, or ready-to-start capacity, is offline but can be brought online quickly. Replacement reserve, sometimes called tertiary reserve, is used to replace committed generation after a disturbance and to restore the original generation schedule. Some markets also use fast-start or high-response reserves to address rapid changes in supply and demand.

Reservekraft can be supplied by a variety of assets. Conventional power plants such as gas or oil-fired units, hydroelectric plants with fast ramping, and pumped-storage hydro facilities are common sources. Battery energy storage systems and, increasingly, demand response programs (where load is temporarily reduced or shifted) are also used to provide fast and flexible reserve.

Procurement and use of reservekraft are typically managed by the system operator or the responsible grid authority. Availability and performance of reservekraft are contracted and paid for through ancillary services or capacity markets. The design and requirements for reservekraft depend on local reliability standards, market structure, and grid codes, with ongoing reforms as generation mixes evolve.

Overall, reservekraft plays a crucial role in maintaining reliability, enabling rapid response to outages and variability, and supporting the integration of more intermittent renewable energy sources.