Varavoimatuotannossa

Varavoimatuotannossa, or reserve power generation, refers to the electric power production that is available to the grid operator but not normally dispatched under normal operating conditions. It functions as a safety net that can be brought online quickly to compensate for unexpected fluctuations in supply or demand, ensuring the reliability and stability of the power system.

The concept originated in the early days of electrification when generators were constructed with excess capacity to cope with unforeseen outages. Modern grids now rely on a range of reserve categories defined by the time required to start up and the power rating. Spinning reserves are units that are as close to full load as possible and can respond in seconds, while non‑spinning or quick‑start reserves can come online within minutes or even seconds, depending on the technology.

Reserve power is supplied by diverse technologies, including fossil fuel plants, gas turbines, hydroelectric dams, pumped‑storage facilities, and increasingly by battery storage systems. The deployment of these resources is coordinated through ancillary services markets or regulatory mandates, and the grid operator monitors reserve levels continuously using real‑time data.

The growth of intermittent renewable sources has increased the need for flexible reserve capacity. In many European countries, the European Network of Transmission System Operators for Electricity (ENTSO‑E) requires that each national system maintain a specified reserve margin. Effective reserve power management therefore remains a cornerstone of energy policy, balancing security of supply with environmental and economic objectives.