Abstract
Hydropower play an important role in providing both baseload and flexible energy on demand. Hydropower provides already flexibility across timescales ranging from seconds to weeks, months and years in many power markets. There will be a strong increase in electricity generation from variable renewable energy (VRE) sources the coming years, because of climate change targets. Flexibility at multiple timescales will be even more important in the future. It is therefore important to modernize, upgrade and extend the existing hydropower fleet—as well as build new hydropower plants to meet demands for renewable energy and flexibility. © 2022 Elsevier Ltd. All rights reserved.