Emergency reserve capacity
Emergency reserve capacity is reserve power the TSO holds or pre-orders to handle major contingencies — generator trips beyond design fault, multiple simultaneous outages, sudden cross-border disconnections. It sits outside the normal FCR/aFRR/mFRR market and is activated only when those routine reserves are exhausted. Estonia's flagship emergency reserve is the 250 MW Kiisa peaker plant.
Emergency reserve capacity (avariireservvõimsus) is reserve power that the TSO holds or pre-orders to handle major contingencies in the electricity system. It is distinct from the normal operating reserves (FCR, aFRR, mFRR) and is activated only when those normal reserves are exhausted or insufficient.
When it activates
Avariireservvõimsus is a last-resort reserve. The contingency events it covers include major generator trips beyond the design fault, multiple simultaneous outages, sudden cross-border disconnections, and the kind of system shocks where ordinary frequency-restoration reserves cannot keep the system inside operational limits. The Bilansi tagamise eeskirjad (Konkurentsiamet-approved 6 November 2025) regulate its procurement and activation.
Estonia: the Kiisa complex
Estonia's flagship emergency-reserve capacity sits at Kiisa, a 250 MW gas-engine peaker plant operated by Eesti Energia and pre-contracted to Elering for fast emergency response. Kiisa was commissioned in 2014 specifically to provide black-start and emergency-reserve capability after the original Russia-coupled grid security calculus shifted, and remains the cornerstone of Estonian emergency reserves post-Continental synchronisation in February 2025.
How it differs from FCR/aFRR/mFRR
FCR, aFRR and mFRR are routine balancing products auctioned daily and dispatched continuously to keep frequency near 50 Hz under normal conditions. Avariireservvõimsus is procured under bilateral arrangements between TSO and capacity owner, paid as a standby fee, and activated only under specific contingency conditions defined in the operating rules. The two reserve categories do not compete in the same market.