Rethinking the Energy Trilemma Index for Energy Security and Sustainability: Critique and the Way Forwards

The Energy Trilemma Index (ETI) plays a key role in assessing countries' energy security, energy equity, and environmental sustainability in static and dynamic contexts. This paper analyses the theoretical background of ETI, its structure, strengths, and limitations in the academic literature, with a particular focus on the challenges posed by reflecting different regional and cultural contexts. The review identifies five major areas of limitations: (1) reliability and methodological robustness, (2) transparency, data accessibility and research applicability, (3) universality and methodological standardisation, (4) policy relevance and ability to track policy implementation and (5) adaptability to dynamic energy system changes. Based on these challenges, the study identifies corresponding opportunities for improvement, including greater methodological transparency and data accessibility, context specific and adaptive weighting, dynamic and forward looking measurement, more robust indicator selection and aggregation procedures, and stronger stakeholder participation and policy integration. These improvements could enhance the analytical robustness, contextual relevance and practical policy value of ETI while preserving its usefulness as a comparative framework for assessing national energy systems.