Concurrent deficit and surplus situations in the future renewable Swiss and European electricity system

European countries aim to achieve net zero CO2 emissions by mid-century. Consequently, the European energy system and particularly the electricity system must undergo major changes. An increasing electrification of the mobility and heating sector is required for decarbonisation, which reserves electricity a central role on the path towards net zero CO2 emissions. However, to meet emission targets, the electricity supply must originate from low emission generation sources. According to the TYNDP 2018 scenarios, the electricity supply in Europe is expected to predominantly originate from renewable energy converters, introducing new challenges to energy systems. Due to the seasonality of renewable energy sources, most European countries, including Switzerland, are expected to face seasonal imbalances of supply and demand in the electricity system. According to national energy strategies of countries with deficits in electricity, the resulting shortages in supply should be covered with imports from their neighbouring countries. This study assesses concurrent deficit and surplus situations among different balancing zones and highly renewable energy systems. Thereby, possible infeasible energy balances are identified by analysing the case of Switzerland and its neighbouring countries Austria, Germany, France and Italy based on published scenarios. The results show, that there are concurrent deficit situations in Switzerland and its neighbouring countries in particular during winter. Hence, the results of this analysis challenge the current energy strategies and the aim to reach net zero CO2 emissions in Switzerland and Europe.