Harmonized life cycle sustainability assessment of advanced hydrogen production technologies for decarbonization

Methodological inconsistencies affect the reliability and validity of the results when conducting comparative life cycle sustainability assessments across different hydrogen production systems. In this regard, the present work aims to use some harmonized life cycle indicators of hydrogen to determine the environmental impacts of renewable hydrogen production. For this purpose, five different configurations of the sulfur‑iodine (S-I) thermochemical cycle are considered for assessment. A consistent methodology is applied across all case studies to ensure robust comparisons and reliable results. The environmental profile of every H 2 production method is characterized by well-known harmonized indicators, namely: (1) carbon footprint, (2) acidification footprint, and (3) non-renewable energy footprint. When they are assessed from a cradle-to-grave perspective, the results show that the choice of oxygen carrier (OC) significantly affects the sustainability performance of hydrogen production systems. Sensitivity analysis results show that the base-case OC pair (ZnO/ZnS) exhibits superior environmental performance with the lowest carbon footprint, acidification footprint, and non-renewable energy demand share of 37.41 %, 6.68 %, and 35.78 %, respectively. However, the OCs pair SnO/SnS, CuO/CuS, and BaO/BaS exhibit poor environmental performance with a significant share in carbon, acidification, and non-renewable energy footprints. • A harmonized framework is developed for the life cycle sustainability assessment of hydrogen production • The LCA of five different configurations of the S-I thermochemical cycle is performed. • The thermochemical cycle employs steps with MeO/MeS. • A consistent methodology is employed for robust and reliable comparisons. • ZnO/ZnS OC pair shows the lowest carbon footprint, acidification footprint, and non-renewable energy demand.