[Comparative Life Cycle Assessment and Carbon Footprint of Typical Hydrogen Energy Products]

To compare the environmental impact and carbon footprint of gray hydrogen, blue hydrogen, and green hydrogen, inventories were obtained through literature research. Some inventories that were not available in China were obtained through foreign inventories combined with localized power conversion. The localized end-point destructive life cycle impact assessment method was used to calculate the environmental impact potential of the raw material acquisition, transportation, and hydrogen production stages of five hydrogen products. The carbon footprint was calculated, and the sensitivity analysis and uncertainty analysis were carried out and compared with the ReCiPe method. The results showed that： ① The environmental impact from large to small was： gray hydrogen （coal） （1 203 mPt·kg^-1） > blue hydrogen （coal） （876 mPt·kg^-1） > gray hydrogen （gas） （492 mPt·kg^-1） > green hydrogen （323 mPt·kg^-1） > blue hydrogen （gas） （252 mPt·kg^-1）. The environmental impacts of gray hydrogen and blue hydrogen were mainly concentrated in climate change, fine particulate matter formation, and fossil fuels. The environmental impacts of green hydrogen were mainly concentrated in climate change, fine particulate matter formation, fossil fuels, and mineral resources. ② The carbon footprint from large to small was： gray hydrogen （coal） （23.79 kg·kg^-1, measured by CO₂eq, the same below） > blue hydrogen （coal） （11.07 kg·kg^-1） > gray hydrogen （gas） （10.97 kg·kg^-1） > blue hydrogen （gas） （3.47 kg·kg^-1） > green hydrogen （1.97 kg·kg^-1）. Direct carbon emissions in the production process of gray hydrogen and blue hydrogen accounted for the largest proportion, whereas that of green hydrogen accounted for a large proportion of power input. ③ Measures to reduce environmental impact and carbon emissions include reducing direct emissions of pollutants and greenhouse gases, reducing power consumption, and strengthening raw material substitution and reduction.