Abstract
Regulated hydropower provides flexible, renewable power generation to balance net electricity generation and demand. It also affects the river ecosystem and threatens the freshwater biodiversity. To protect the river ecosystem and improve the sustainability of the production, the operation is subjected to environmental regulation. Environmental requirements are often defined in the hydropower plants’ concessions in line with European and national laws and policies. These constraints can limit the electricity production or the operational flexibility of the hydropower plants and are usually associated with a cost for the hydropower owner and the society. Balancing environmental preservation with flexible hydropower requires careful evaluations of the economic and environmental impacts. In this research, a novel framework is developed and assessed through two case studies with different environmental regulations to justify the metrics and demonstrate the interplay between economic and environmental considerations. The framework contains five metrics to quantify the effects of operational constraints on the river sustainability — salmon smolt production and the EnviPEAK classification system — and on the hydropower flexibility — the flexibility factor, net yearly flexibility income and power production. The economic evaluation is performed with a stochastic, local hydropower scheduling model used by hydropower producers. The framework is intended for regulators and stakeholders in revision of concessions for hydropower production to evaluate suggested measures towards the objective of current policies, such as water framework directive, targets for renewable power generation and requirements for flexibility in the power system, providing policy insights for sustainable hydropower development and environmental sustainability.