State of the Art of Biomethane Production in the Mediterranean Region

The Mediterranean region is increasingly confronted with intersecting environmental, ag-ricultural and socio-economic challenges, including biowaste accumulation, soil degra-dation and high dependency on imported fossil fuels. Biomethane, a renewable substitute for natural gas, offers a strategic solution that aligns with the region's need for sustainable energy transition and circular resource management. This review examines the current state of biomethane production in the Mediterranean area, with a focus on Anaerobic Di-gestion (AD) technologies, feedstock availability, policy drivers and integration into Cir-cular Bioeconomy (CBE) framework. Emphasis is placed on the valorisation of regionally abundant feedstocks such as olive pomace, citrus peel, grape marc, cactus pear (Opuntia ficus-indica) residues, livestock manure and the Organic Fraction of Municipal Solid Waste (OFMSW). The multifunctionality of AD—producing renewable energy and nutrient-rich digestate—is highlighted for its dual role in reducing Greenhouse Gas (GHG) emissions and restoring soil health, especially in areas threatened by desertification such as Sicily (Italy), Spain, Malta and Greece. The review also explores emerging innovations in biogas upgrading, nutrient recovery and digital monitoring, alongside the role of Renewable En-ergy Directive III (RED III) and national biomethane strategies in scaling up deployment. Case studies and decentralised implementation models underscore the socio-technical feasibility of biomethane systems across rural and insular territories. Despite significant potential, barriers such as feedstock variability, infrastructural gaps and policy fragmen-tation remain. The paper concludes with a roadmap for research and policy to advance biomethane as a pillar of Mediterranean climate resilience, energy autonomy and sus-tainable agriculture within a circular bioeconomy paradigm.