A residual load-based methodology for assessing climate change impacts on electricity systems and identifying extreme events

The planning and operation of electricity systems with high shares of variable intermittent renewable energies (VRE) require a solid understanding of weather impacts, which are becoming increasingly influenced by climate change and associated extreme events. However, there is a lack of standardized methodologies for identifying extreme events and systematically assessing climate change impacts on power systems. This study addresses this gap by applying a residual load (RL)-based framework that integrates climate projections with indicators of a VRE-dominated future power system, enabling the systematic detection and analysis of extreme events. RL is defined as the difference between electricity demand and VRE generation. The proposed RL-based framework assesses climate-change impacts on power systems and identifies extreme events under future climate scenarios. This is achieved through a multi-annual analysis combining a decarbonization pathway with moderate and strong climate-change scenarios. The analysis evaluates changes in specific RL indicators across geographical scales, including the EU, and Austria as a country case. In Austria, stronger climate change shifts peak periods of residual load (PPRL) towards summer, indicating a growing influence of heatwaves. At the same time, PPRL frequency increases to up to six events per year, while maximum event durations decrease from 46–53 to 33–34 days. At the EU level, PPRL events are less frequent (1–2 per year) and shorter (around 10 days, with maximum durations of 20 days). This highlights the importance of strong interconnection within the European power system, as cross-border exchanges can support regions and countries during extreme-event periods.