From climate goals to energy security: Mapping Europe's biomethane implementation gap, with Greece as a case in point

The geopolitical destabilization following the 2022 invasion of Ukraine has fundamentally reframed the European energy transition, elevating biomethane from a decarbonization tool to a strategic security asset under the REPowerEU plan. However, despite the ambitious European Union-wide target of 35 billion cubic meters by 2030, this study identifies a critical “implementation gap” characterized by significant regulatory heterogeneity. Employing an integrative policy review and a comparative clustering approach, we analyze the divergence between “Accelerating Markets” in Northern and Western Europe and “Dormant Markets” in the South and East. The analysis reveals a “two-speed” Europe: while mature markets such as France and Denmark utilize comprehensive “push-pull” support mechanisms to ensure grid injection, high-potential regions often face a “policy vacuum” and a lack of bankable revenue streams. Greece is examined as a focal case study of this paradox, with high specific feedstock potential from agro-industrial residues but negligible market penetration. We assess the transformative potential of the recently enacted Greek Law 5215/2025, which introduces a targeted capital subsidy scheme, arguing that its capital expenditure-support model aligns with a necessary “Second Wave” of biomethane policies that prioritize waste valorization over energy crops. The findings suggest that bridging the North-South asymmetry requires moving beyond theoretical targets to implement tailored frameworks that address the high upfront infrastructure costs in emerging markets.