Structural patterns and energy productivity in the EU-27 decarbonization process

Decarbonization is one of the defining challenges of the twenty-first century for the European Union, crucial to ensuring long-term sustainability, competitiveness, and energy security. This study pursues three objectives: (1) to identify homogeneous groups of EU countries according to their energy structure and dynamics; (2) to assess technical efficiency in decarbonization processes; and (3) to analyse the drivers of energy productivity changes within the EU-27 over the period 2015–2023. A multi-method approach is applied, combining Ward.D2 clustering, a non-convex metafrontier, and a sequential Malmquist index to estimate efficiency and productivity, complemented by a Random Forest algorithm to determine structural and technological factors. Results show that technological change has been the main source of convergence, while technical efficiency improvements have been more moderate. Public R&D expenditure in energy, green patents, and tertiary education emerge as the most influential drivers of energy productivity, underscoring the central role of innovation and human capital in modernizing the European energy system. The findings provide policy-relevant insights for designing flexible and targeted strategies to achieve an effective, equitable, and sustained decarbonization pathway across the EU-27.