Energy security and resilience: Revisiting concepts and advancing planning perspectives for transforming integrated energy systems

Recent events, including the pandemic, geopolitical conflicts, supply chain disruptions, and climate change impacts, have exposed the critical need to ensure energy security and resilience in energy systems. Therefore, this work initially reviews existing definitions and interrelations between energy security and resilience, conceptualising these terms in the context of energy system transformations. To highlight key challenges, especially to energy system resilience, it introduces a classification of disturbances into shock events and slow burn processes. Examples of each category illustrate their distinct impacts on technical, economic, and environmental system performance over time. To address these challenges, relevant recourse options are compiled across resilience capacity levels and system planning horizons, emphasising actionable strategies for an increasingly integrated energy system. Finally, based on the above-mentioned aspects, policy recommendations are proposed to integrate shock events and slow burn processes into future energy system planning, enabling forward-looking decision-making and system design to analyse and mitigate potential disruptions.