Insights on microalgae-based technologies with potential impact on global methane budget – Perspectives for industrial applications

The European Union's Methane Action Plan outlined policies and targets supporting the Global Methane Pledge to cut CH4 emissions by 30% by 2030, yet urgent implementation is needed to treat medium and diluted CH4 streams. Microalgae-based technologies offer a groundbreaking solution, merging CH4 mitigation with biomass valorization to drive sustainable industrial practices. This review examines three key applications: photosynthetic biogas upgrading, a viable alternative to physical/chemical methods, producing biomethane and valuable algal biomass; microalgae-methanotroph co-cultivation, a promising but underdeveloped method for diluted CH4 streams; and CH4-producing microalgae, unveiling a novel route for biomethane production. Despite their potential, significant research gaps remain, particularly in reactor design, culture conditions, and large-scale viability. By addressing these challenges, microalgae could revamp CH4 management, bridging environmental goals with bioeconomic progress. This review calls for policy updates, intensified research, and industrial engagement to unlock microalgae's full potential in CH4 mitigation and valorization.