The impact of glacier shrinkage on energy production from hydropower-solar complementarity in alpine river basins.

Variable energy sources such as solar and runoff sources are intermittent in time and space, following their driving hydro-meteorological processes. Recent research has shown that in mountainous areas the combination of solar and hydropower has large potential (termed complementarity) to cover the temporal variability of the energy load and, by this mean, to facilitate integration of renewables into the electricity network. Climate change is causing widespread glacier retreat, and much attention is devoted to negative impacts such as diminishing water resources and shifts in runoff seasonality. However, the effects of glacier shrinkage on complementarity between hydropower and solar energy sources have been disregarded so far. This research aims at filling this gap. Data from the Eastern Italian Alps are used for the analysis. The Decision Scaling approach is used to analyze the electric energy system sensitivity and vulnerability to change in precipitation, temperature and glacier coverage. With this method, the electric energy system is first subject to a scenario-independent climate stress test, while projections from Regional Climate Models (RCMs) are then used to infer the likelihood of the future climate states and subsequently changes in complementarity of energy production. Results show that glacier shrinkage and increasing temperatures induced by climate change lead to a marked shift of seasonal hydropower production. As a consequence, the complementarity between hydropower and solar photovoltaic increases in a marked way in the basin with the largest original glacier coverage. Changes in complementarity are less significant in larger basins characterized by less glacier contribution.