Bio and green hydrogen: A comparative review of regulatory trends, industrial feasibility, and technological perspectives

Hydrogen has become a key component of global energy transition. Green and biohydrogen are receiving growing attention, but their comparative industrial feasibility remains underexplored. This review article investigates technologies with medium-to-high maturity: pyrolysis, gasification, dark fermentation, alkaline water electrolysis (AWE), proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis cells (SOEC). A scoring model based on industrially relevant key performance indicators (KPIs) – maturity, application scale, hydrogen yield, energy efficiency, carbon footprint, cost, land occupancy – was developed to assess their industrial feasibility. The results reveal that the optimal technological solution lies in the trade-off between performance indicators and supply chains integration. While AWE and PEM show greater maturity, they suffer from high costs. In contrast, biohydrogen routes prove feasible industrial applications but are currently less considered from both regulatory and incentive perspectives. This work highlights the dual potential of bio and green hydrogen and proposes a decision-support framework for technology selection.