Strength of co-variability of energy droughts highly region dependent 

The European electricity system is becoming increasingly dependent on weather conditions, which influence both electricity demand and production. Non-linear dependence of the electricity system on the weather conditions can lead to energy droughts – high demand coinciding with low renewable energy production – even under non-extreme meteorological conditions. Weather conditions driving energy droughts can transcend national boundaries, which leads to the possibility that multiple countries experience concurrent energy droughts, potentially leading to a widespread energy crisis. We examine the interplay between large-scale weather conditions and the risks of co-occurrence and opportunities of disjoint occurrence of energy droughts in renewable electricity systems in European countries. We analyse 1600 years of modelled energy data against meteorological conditions from large ensemble climate model simulations to identify patterns of co-variability of energy droughts in the present-day climate.We find a strong spatial variability in the risk for concurrent energy droughts within Europe, depending on a country’s renewable energy mix and the region's response to specific large-scale meteorological patterns (weather regimes). Some countries, such as Latvia and Slovenia, mostly experience energy droughts isolated from their neighbouring countries. However, we also find clusters of countries that experience concurrent energy droughts. This is the case for the North Sea region, and many countries in central/eastern Europe. Here, there is limited potential for cooperation, putting these countries more at risk of energy crises. Finally, we differentiate between moderate and extreme energy droughts, which have different co-occurrence signatures. This implies that an interconnected electricity grid has potential to resolve some moderate events, but is less effective in the extreme events.