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This prospective life cycle assessment (LCA) compares the environmental impacts of alkaline electrolyser (AE) and proton exchange membrane (PEM) electrolyser systems for green hydrogen production with a special focus on the stack components. The study evaluates both baseline and near-future advanced designs, considering cradle-to-gate life cycle from material production to operation. The electricity source followed by the stacks are identified as major contributors to environmental impacts. No clear winner emerges between AE and PEM in relation to environmental impacts. The advanced designs show a reduced impact in most categories compared to baseline designs which can mainly be attributed to the increased current density. Advanced green hydrogen production technologies outperform grey and blue hydrogen production technologies in all impact categories, except for minerals and metals resource use due to rare earth metals in the stacks. Next to increasing current density, decreasing minimal load requirements. improving sustainable mining practices (including waste treatment) and low carbon intensity steel production routes can enhance the environmental performance of electrolyser systems, aiding the transition to sustainable hydrogen production.
Krishnan et al. (Sat,) studied this question.