Assessment of flow ramping in water bodies impacted by hydropower operation in Norway - Is hydropower with environmental restrictions more sustainable?

Jo Halvard Halleraker; Mahmoud Saber Kenawi; Jan Henning L'Abée-Lund; Tor Haakon Bakken; Knut Alfredsen

doi:10.1016/j.scitotenv.2022.154776

Assessment of flow ramping in water bodies impacted by hydropower operation in Norway - Is hydropower with environmental restrictions more sustainable?

Sci Total Environ. 2022 Aug 1:832:154776. doi: 10.1016/j.scitotenv.2022.154776. Epub 2022 Apr 4.

Authors

Jo Halvard Halleraker¹, Mahmoud Saber Kenawi², Jan Henning L'Abée-Lund³, Tor Haakon Bakken², Knut Alfredsen²

Affiliations

¹ Norwegian University of Science and Technology (NTNU), Department of Civil and Environmental Engineering, S.P. Andersens veg 5, N-7491 Trondheim, Norway; Norwegian Environment Agency, P.O. Box 5672 Torgarden, N-7485 Trondheim, Norway. Electronic address: jo.h.halleraker@ntnu.no.
² Norwegian University of Science and Technology (NTNU), Department of Civil and Environmental Engineering, S.P. Andersens veg 5, N-7491 Trondheim, Norway.
³ Norwegian Water Resources and Energy Directorate, P.O. Box 5091, Majorstua, N-0301 Oslo, Norway.

PMID: 35390377
DOI: 10.1016/j.scitotenv.2022.154776

Abstract

Hydropower production is a key electricity generation technology in many parts of the world which can play a significant role in the transition towards a green and clean energy system. Hydropower can mobilize flexible energy on demand (hydropeaking) to balance out intermittent electricity from wind and photovoltaics. Adoption of hydropower as a peaking power source could lead to increased frequency of flow ramping in rivers downstream hydropower tailraces, which is one of the main stressors for riverine biota in alpine rivers. Both planned and accidental shutdowns of hydropower turbines need ecological mitigation. Our survey revealed that >3000 km of rivers downstream ca 800 hydropower plants in Norway may be ecologically impacted by non-natural flow fluctuations, and few have appropriate mitigation thresholds. A considerable eco-friendly peaking service may come from the Norwegian hydropower portfolio of over 19 GW installed capacity, with outlets into fjords, reservoirs or other large water bodies which normally dampen the ecological impacts of flow ramping. Intensive flow ramping occurs with irregular intervals from most types of hydropower. Although the highest frequency of stops were revealed in hydropower turbines not impacting river flow from storage hydropower, a significant number of turbine flow stops lasting over half a day in most types and categories of diversion hydropower. We suggest that further emerging ecosystem-based mitigations need to be adapted in hydropower licenses. This includes operational thresholds for both up and down ramping, constructional measures like by-pass valves, retention basins and increased base-flow or flow cap to ensure sustainability for hydropower operations. Our data reveal some of the most intensive hydropeaking operations from hydropower impacting longer rivers. Hence, our data underpins the potential for restoring downstream modified flow by ecosystem based measures related to both up and down ramping events in many regulated rivers.

Keywords: Ecological mitigation; Flow restoration; Flushing; Hydropeaking; Stranding.

MeSH terms

Biota
Ecosystem*
Norway
Power Plants
Rivers*
Water

Substances

Water