Olkiluoto 3 joined the reserve market in autumn – but what does it mean?

– At every moment, the amount of electricity produced needs to match the amount consumed. The reserve market is used to balance the electricity system in case of temporary over-production of electricity. The market is maintained by the national grid company Fingrid, Somerkoski says.

Reserve capacities refer to, for example, power plants, electricity consumers, and energy storages that can modify their output as needed.

– Fingrid acquires the reserve capacities from the reserve market it maintains and the operators participating in the reserve market receive compensation for it. OL3 joined the market as of 1 September, as the first unit in Olkiluoto. However, OL3 participates in the reserve market with only a small share of the total production capacity of the plant unit.

Anybody who has followed TVO’s production graphs in recent years has noticed that the production of nuclear electricity has also been reduced in conditions where the available production has exceeded consumption. This refers to the 24-hour plans for production, however. The production plans for the Olkiluoto units and any regulation actions with a commercial basis are always determined on the previous day. The reserve market is about something else completely.

– The reserve market does not affect the hourly spot price used as the basis for pricing of electricity for households, for example. The spot price is determined based on production during the previous day and the consumption forecasts. The reserve market, on the other hand, is used to regulate electricity production only momentarily based on transient requirements in the electricity system, Somerkoski sums up.

Text: Ville Kulmala
Photo: Tapani Karjanlahti

This article was first published in News from Olkiluoto Magazine which was released on 27 November.