Prospective life cycle sustainability assessment and benchmarking of hydrogen from solid oxide electrolysis coupled with concentrated solar power

Achieving sustainable hydrogen systems requires balancing environmental, economic and social aspects. In this regard, research on the life-cycle sustainability of emerging pathways such as solid oxide electrolysis (SOE) coupled with concentrated solar power (CSP) remains limited. This study presents a prospective life cycle sustainability assessment (LCSA) of hydrogen production via SOE coupled with CSP, benchmarked against hydrogen from steam methane reforming (SMR) as a conventional counterpart. By following the latest guidelines for LCSA of hydrogen-related systems developed within the SH2E project, this study applies consistent methodological choices across sustainability dimensions (e.g. functional unit definition), while transparently addressing model asymmetries. Results highlight notable differences in hotspots across dimensions and indicators. The CSP section dominates environmental impacts due to high material demand, while economic hotspots additionally include electrolysers and operational wages. Social impacts are primarily linked to the high relative share of worker hours in the Spanish hydrogen production facility itself, with added supply chain risks associated with chromium extraction in Kazakhstan and natural gas sourcing from Algeria. Even though conventional hydrogen from SMR outperforms hydrogen from SOE in four out of seven sustainability indicators, the latter offers promising results in terms of lower carbon footprint, reduced fair salary risk, and enhanced prospects for economic growth. Overall, these findings highlight the potential of SOE to contribute to a sustainable hydrogen economy, while they also stress areas (e.g. cost competitiveness, resource efficiency, and supply chain risk management) where sustainable-by-design research is essential to mitigate burden-shifting across impact categories and sustainability dimensions.