Comparative review of carbon emissions from hydrogen production technologies: The hydrogen color characteristic of biomass-based manufacturing

Current hydrogen production is largely dependent on fossil fuels, which contribute significantly to carbon emissions. Biomass is a renewable and carbon-neutral resource. Biomass-based manufacturing using biomass as feedstock can recycle and utilize biomass waste while producing clean biohydrogen energy, reducing the high emissions associated with fossil energy. This research conducts a systematic review of the carbon emissions from different hydrogen production methods. The calculation results indicate that the carbon emissions from biomass-based manufacturing range from −14.8 to 0.79 kg CO2/kg H2. Measures such as combined heat and power, Carbon Capture, Utilization and Storage and resource utilization of VFAs technologies contribute significantly to enhancing the carbon reduction benefits of biomass-based manufacturing. Based on these results, it is found that biohydrogen obtained through biomass-based manufacturing technologies is carbon-negative hydrogen which can be defined as “ultra-green hydrogen” within the color coding of the hydrogen rainbow. This review also comprehensively evaluates the techno-economic feasibility, scalability and commercialization potential of “ultra-green hydrogen”. Recent studies indicate that biohydrogen has achieved notable advancements in technological maturity, cost competitiveness, and feedstock supply chain, yet further refinements remain imperative. While demonstrating competitive parity with green hydrogen in production costs and ECE, its large-scale infrastructure development and market penetration still depend on enhanced governmental policy support and the establishment of standardized management frameworks. By introducing the novel concept of “ultra-green hydrogen”, this review advances both academic and industrial understanding of biohydrogen, offering a strategic blueprint for its integration into decarbonization.