Transformation of the European Energy Sector Under the New Energy Architecture: A Multi-Criteria Assessment of Decarbonization, Energy Security, and Strategic Energy Autonomy

The transformation of the European Union’s energy sector increasingly requires the simultaneous pursuit of decarbonization, energy security, and strategic energy autonomy, which necessitates a comprehensive assessment of the processes shaping a new energy architecture. The aim of this study is to develop a methodological approach to the multi-criteria assessment of energy transformation across the 27 European Union countries over the period 2015–2024. The proposed approach combines a system of quantitative indicators, normalization procedures, the calculation of sub-indices of energy security, decarbonization, and strategic energy autonomy, and their subsequent aggregation into a Composite Energy Transformation Index. To identify structural differences among countries, Ward’s clustering method was additionally applied. The results indicate an overall positive trend in energy transformation across all EU countries; however, the pace and structural balance of these processes differ substantially. Three typical transformation profiles were identified: decarbonization-oriented, asymmetric, and advanced integrated. The highest average level across the three dimensions was observed in Denmark, Italy, and Romania; this profile, however, rests largely on their domestic oil and gas reserves and disappears when the reserve-to-production indicators are excluded. Country rankings are robust to alternative weights, whereas the profiles are weakly separated and are best read as positions along a continuum. The findings confirm the multidimensional nature of the EU energy transformation and the need to differentiate management decisions according to the specific features of individual countries’ transformation profiles.