The secondary reserve is an important instrument for stabilizing the electricity grid and is one of the control energies that become active when fluctuations occur in the electricity grid. While the primary reserve reacts to grid frequency deviations within seconds, the secondary reserve is usually activated after 30 seconds and can supply energy continuously for up to 15 minutes in order to restore the balance between electricity generation and consumption. This staggering is necessary to ensure a staggered stabilization of the grid.

In Europe, and particularly in Austria, the secondary reserve plays a central role in maintaining grid stability. The European electricity grid functions as a closely interconnected system in which a disruption in one country can have an impact on several neighboring countries. Due to its geographical location, Austria is an important transit country for the European electricity market and plays a key role in ensuring that the necessary balancing energy is provided in the event of frequency deviations.

In Austria,hydropower plants are a preferred source for the provision of secondary reserves. Due to their flexibility and fast response time, they can adjust their output at short notice if necessary, which makes them particularly suitable for responding to frequency fluctuations. One example of this is the Limberg pumped storage power plant in Kaprun, which makes a significant contribution to stabilizing the electricity grid by quickly ramping its generators up or down.

In addition to hydropower, gas and steam power plants also play an important role in the provision of secondary reserves. These plants can react quickly to fluctuations in the electricity grid and supply the energy required to stabilize the grid again. At a time when renewable energies such as wind and solar power are making up an increasingly large proportion of the energy mix, the importance of secondary reserve becomes even more apparent. As wind and solar power are weather-dependent and not available at all times, conventional power plants must be able to compensate for these fluctuations by quickly adjusting their output.

The secondary reserve is activated automatically by the transmission system operators (TSOs), which in Austria is coordinated by Austrian Power Grid (APG). APG continuously monitors the grid frequency and can instruct the relevant power plants to adjust their output in the event of a deviation. This automated control ensures that the secondary reserve is used quickly and effectively to prevent impending blackouts.

Remuneration for the provision of secondary reserve is paid via the balancing energy market. Power plant operators offer their output on this market and are paid for providing energy within a short period of time when required. The costs of providing the secondary reserve are ultimately passed on to electricity consumers, as the grid operators must ensure that enough balancing energy is available at all times to keep the grid stable.

An important aspect in the further development of the secondary reserve is the increasing integration of storage systems. As the energy transition progresses and more renewable energy is fed into the grid, innovative storage solutions such as battery storage systems are becoming increasingly important in order to compensate for short-term fluctuations in the grid. In Austria, there are already projects aimed at using battery systems as part of the secondary reserve in order to further increase the flexibility of the electricity grid.

In summary, it can be said that the secondary reserve is an indispensable element of grid stability in the European and Austrian electricity market. It ensures that the energy required to stabilize the electricity grid and guarantee security of supply is available quickly and reliably in the event of grid disruptions. Especially in times of transition to renewable energies, the secondary reserve remains a key mechanism for avoiding power outages.