Two-Speed Europe in Renewable Transition? Sigma And Beta Convergence of Renewable Energy Shares in the EU-27 (2004–2024)

This study investigates whether the renewable energy transition in the EU-27 has followed a common path or a “two-speed” pattern characterised by persistent leaders and laggards. Although successive EU policy frameworks RED I, RED II, and the European Green Deal established shared objectives, empirical evidence on convergence dynamics remains limited for the post-2020 period, particularly in light of the methodological revision introduced in the SHARES framework in 2021. This paper addresses this gap by extending convergence evidence through 2024 and explicitly accounting for the definitional break. Using harmonised EUROSTAT data for a balanced panel of 27 Member States over 2004–2024 (567 country-year observations), we apply σ-convergence, based on the cross-sectional standard deviation of log renewable shares tested via HAC-robust trend regression, and β-convergence, estimated through both an endpoint cross-sectional specification and a fixed-effects panel model with country-clustered standard errors. Robustness checks include a logit transformation appropriate for bounded shares and separate estimation for the 2004-2020 and 2021-2024 subperiods. The findings reveal a dual pattern. Relative convergence is strong: log-based dispersion declined from 1.2567 in 2004 to 0.3997 in 2024, and β-convergence implies an annual adjustment rate of 7-8% with a half-life of approximately nine years. However, absolute stratification persists the max-min gap widened from 38.325 to 48.510 percentage points between 2004 and 2024. The results support a “two-speed” interpretation of the EU renewable transition, combining relative convergence with persistent level disparities.