Electricity supply and hydropower development in Switzerland

Introduction According to the Swiss Energy Strategy 2050, which takes into account the phase out of the existing nuclear power plants, the mean annual hydropower production must be increased by 1.5 TWh/a under present framework conditions, eventually reaching 3.2 TWh/a if conditions are optimized (SFOE, 2016). In view of environmental and socio-economic constraints, this foreseen increase is extremely challenging and can be reached only by innovative and sustainable solutions for new hydropower plants (HPP) and by the extension and optimization of existing schemes including reservoirs. Furthermore, the expected increase of power production from small hydropower plants (SHPP) requires the development of criteria for a careful site selection as well as strategies to optimize power production within a river network while at the same time minimizing the negative impacts on stream ecology. In this context, the Swiss Government is funding since 2013 a Swiss Competence Center for Energy Research on Supply of Electricity (SCCER-SoE) with the aim of developing fundamental research and innovative solutions in the fields of geo-energies and hydropower. Given the recent and present harsh contextual conditions, there is a growing consensus rather to favour the extension of the existing large hydropower schemes and reservoirs than to exploit the last natural rivers with a large number of small hydropower plants. Also, the effect of climate change will not only change the availability of water resources in time but also change the behaviour of the catchment areas by an increased sediment yield into reservoirs and more frequent natural hazards, and thus considerably endangering waterpower production in the near future. In fact, the critical period of electricity supply in Switzerland is still the winter semester (October-March), period during which on average 3.7 TWh have been imported over the last 12 years, which is almost 11% of the electricity demand in winter. In order to guarantee a safe energy supply also during critical periods, Switzerland has to increase its storage capacity by new reservoirs where possible and mainly by increasing the volumes of existing ones. The paper presents the current context for energy transition and hydropower development in Switzerland, summarizes the activities on hydropower infrastructure research carried out over the past 3 years and presents the development objectives for the coming four years. The focus is on the increase of operational flexibility and winter production. The plan includes three demonstrators, the first on recently commissioned small-hydro schemes, the second on sediment release through the powerhouses and the third being a multidisciplinary project in the multireservoir multi-powerplant scheme operated by Kraftwerke Oberhasli in the Bernese Oberland.