ALBERT

Description: Solbergfoss Hydropower Plant is one of several run-of-the-river plants developed in a cascade on the main stem in the lower part of Glomma river, the longest river in Norway, all benefitting from the same upstream regulations. Water consumption from hydropower production is primarily due to evaporation from reservoir surfaces, hence reducing the annual flow downstream. At the same time reservoirs increase the water availability in dry periods. In article number 1600018 by Tor Haakon Bakken,* Ånund Killingtveit, and Knut Alfredsen the state of art within this field of science is reviewed. The review revealeds a wide range of estimates and a meteorology that does not capture all the specifics of hydropower technology.

Description: This paper reviews published estimates of water consumption from hydropower production and the methodologies applied. Published values range from negative to more than 115 000 m 3 MWh −1 . Most gross water consumption rates are in the range 5.4–234 m 3 MWh −1 , while most net values are in the range 0.2–140 m 3 MWh −1 . Net values are often less than 40% of the gross values, sometimes only 1% of the gross water consumption estimates. The extremely wide range in estimates is explained by an inconsistent methodology and the very site-specific nature of hydropower projects. Scientific challenges, such as allocation from multipurpose reservoirs, and spatial assignments in river basins with several hydropower plants, affect the results dramatically and remain unresolved. As such, it is difficult to propose “typical values” for water consumption from hydropower production. This paper points out directions of research in order to prepare a consistent and improved methodology for the calculation of water consumption from hydropower projects. This should take into account the role of reservoirs in the provision of a large range of water services, as well as providing regulated power to the energy system. This paper reviews published estimates of water consumption from hydropower production and the methodology behind these numbers. The review reveals very large variations, explained by an inconsistent methodology and the very site-specific nature of hydropower projects. We also argue that there is a lack of understanding of the role of reservoirs in water resources management and in the energy system.