Technological advancements in biohydrogen production and downstream processing for green energy transition: A review

A rapid transition toward sustainable and clean energy is necessary for a secure energy future in today's dynamic world. Biohydrogen produced from waste biomass is gaining momentum; however, raw biohydrogen comprises tracer impurities, and its commercial use further requires extensive downstream technologies. Conventional purification strategies offer great selectivity with the promise of modular and low‐energy operation and can provide purities up to 99.99% with recoveries of 80%–90%, whereas storage of ~71 kg/m 3 at −253°C biohydrogen consumes ~30% of its heating value. However, advanced solid‐state carriers can achieve greater than 7–9 wt % at −196.15°C, though room temperature performance remains limited and its techno‐economic and life cycle analyses are crucial for its scalability and sustainability. Despite challenges of energy intensity, material degradation, and artificial intelligence‐driven process optimization have shown optimistic future promises. This review comprehensively analyzes advancements in biohydrogen downstream technologies, evaluating their potential to facilitate a clean energy transition.