Abstract
As variable renewable energy (VRE) accounts for an increasing share of the power mix, the need for flexible capacity to balance short-term variability is rising. Hydropower, and particularly pumped-storage, offers an effective way of providing this flexibility. This work studies one of the largest proposed expansion projects in Norway in the Røldal-Suldal hydropower system (RSK). Using the medium-term hydropower scheduling model Prodrisk, we demonstrate the societal benefit of expanding hydropower capacity and pumped-storage. In particular, the expansion allows a larger share of generation to be shifted into periods with high prices, increasing the flexibility factor of the RSK system from 1.20 to 1.58. We also show how one can cope with certain limitations of the optimization method used in Prodrisk when performing investment analyses, demonstrated for a scenario-dependent constraint in the RSK system.