The role of interconnectors to mitigate energy droughts in a highly renewable power system

Highly renewable power systems can regularly experience system stress derived from weather variability, as weather is a driver of both electricity demand and renewable energy generation. Stress events emerge when periods of high demand coincide with periods of low renewable electricity generation. As European power systems become more interconnected, cross-border electricity exchange using these electricity interconnectors offers the potential to reduce the severity of these stress events.

This study investigates the role of interconnectors in mitigating energy drought events in a future European power system representative of 2030. To this end, the DestinEE power system model is driven by 75 years of meteorological data from the Pan-European Climate Database to construct a long-term time series of renewable generation, electricity demand, and inter-regional power flows. Periods of extreme stress events are identified in this time series, and the electricity exchanges across interconnectors are analysed during these events. Great Britain and Ireland are used as case studies due to their position at the edge of the European network, and the analysis includes regions which are connected to those two countries.

The results present that events occur during an extended winter period, from October to March, and that their duration can reach up to five days. A second part of the analysis investigates the co-occurrence of events between neighbouring regions. This reveals that simultaneous stress events are common across northwestern Europe, although their frequency varies greatly between regions.

During energy drought events, neighbouring regions can contribute to mitigating system stress through electricity imports. In well-connected areas, interconnectors offer a consistent reduction in stress, supported by multiple links to regions with diverse generation portfolios, including dispatchable and complementary renewable sources. In contrast, regions with less connectivity show a more variable response, as support depends on both the availability of neighbouring generation and the risk of simultaneous stress or transmission constraints; while most cases show a mitigating effect by interconnectors, occasional coincident events and limited transfer capacity can lead to reverse flows, temporarily reducing the overall benefit. As a result, interconnectors generally provide effective mitigation of energy droughts, although their benefits vary from one region to another.

Consistent with these results, spatial connectivity plays a key role in managing weather-driven energy risks, while also revealing clear regional differences in the benefits provided by interconnectors. In future European power systems characterised by high renewable dependence, the resilience benefits of interconnection are therefore likely to depend on both network structure and the occurrence of concurrent stress in neighbouring regions. These findings contribute to a better understanding of the vulnerabilities and resilience of interconnected power systems under climate-driven variability.