A new tool to assess the technical, economic, and environmental impacts of green hydrogen generation via water electrolysis using a multi-criteria decision analysis model

Green hydrogen can play a crucial role in reaching net-zero emissions across various sectors. Whilst global hydrogen demand reached approximately 100 Mt in 2024, low-emission hydrogen made up less than 1 % of the supply. Current forecasts indicate that the supply could reach 37 Mt per year by 2030, though only about 4.2 Mt per year is already committed through operational or FID projects, highlighting both rapid growth and the challenge of scaling deployment of low-emission hydrogen. Large-scale water electrolysis projects to produce green hydrogen must consider complex trade-offs between economic viability, technical feasibility and environmental impacts. Herein we present a new Multi-Criteria Decision Analysis model that ranks various green hydrogen production pathways through water electrolysis, taking into account water resource availability and electrolyser technologies, and combining both techno-economic and sustainability scores. Our results highlight the importance of spatial distribution between process stages, technology readiness (with trade-offs between alkaline and proton exchange membrane electrolysers), and system optimisation, to reduce cost and improve the sustainability of operation. In particular, the application of our model to a case study in Aberdeenshire (Scotland, UK) indicates that alkaline electrolysers in combination with optimised seawater membrane distillation, or rainwater ultrafiltration, could prove the most sustainable options for green hydrogen deployment in the region, with waste heat recovery reducing water supply costs by up to 93 %, and seawater treatment costs dropping by over 70 % after optimisation. Our new tool can be translated to other regions and countries to carry out early-stage feasibility and environmental impact studies, supporting strategic policy decisions for green hydrogen deployment. • A new tool is developed to assess hydrogen generation via water electrolysis. • We apply a new Multi-Criteria Decision Analysis model to study sustainability. • Water resources and electrolyser technology readiness are considered. • The tool is successfully applied to a case study in the Aberdeenshire region (UK). • Alkaline electrolysers with optimised seawater membrane distillation is one optimal option.