Sustainability of green hydrogen technologies depends on energy mix and supply chain

A sustainable international green hydrogen supply chain is crucial for achieving net-zero. Here, we performed a spatial-temporal prospective life cycle assessment of twenty international supply chain scenarios in 2023, 2030, 2040, and 2050 across five hydrogen production technologies (three based on water electrolysis and two on biomass conversion) in fourteen countries. The results underscore the substantial roles of the energy mix and supply chain configuration in shaping green hydrogen sustainability. In 2023, electrolysis-based systems show higher global warming impacts than biomass-based ones. Along the net-zero pathway, ecological impacts vary across scenarios. By 2050, proton exchange membrane electrolysis and dark fermentation exhibit the largest and smallest reductions in global warming impacts, respectively. The most sustainable chain involves manufacturing Proton the United States, identified using a multi-criteria decision analysis method, exchange membrane electrolysis systems in the United Kingdom, with 50% exported to that evaluates overall performance across environmental indicators.