Powering future Europe through variable renewable energy droughts

Electrification and growing shares of wind and solar power increase the energy systems’ vulnerability to wind and solar droughts, prolonged periods of low wind speeds and solar irradiation. This work examines the system operation and adequacy in fourteen countries with a high share of variable renewables and hydrogen using the open-source North European Backbone energy system optimization model. The analysis is based on the Distributed Energy 2035 scenario from the European Network for Transmission System Operators’ Ten Year Network Development Plan (TYNDP) 2024, a policy-aligned, highly ambitious, and widely used scenario. Unlike many renewable drought studies that rely almost exclusively on wind and solar as primary energy sources, the adopted scenario includes a diversified supply portfolio, thus covering a wider range of potential issues and system dynamics. We expand the original TYNDP 2024 model runs from 3 to 35 climate years, which is critical for the robust assessment of system vulnerability. The results show that observed lost load (LL) has strong seasonality with 99.8% of all LL occurring from November to March. LL events are closely associated with continent-wide wind droughts, during which wind capacity factors can fall to single-digit percentages for several consecutive days; in the most severe week, aggregate wind generation declines from approximately 400 GW to 100 GW. Correlation between residual demand and LL with weekly aggregation is strong (Spearman coefficient 82.1–85.0%). Correlation declines significantly for daily aggregation but is not significantly affected by aggregation method.