Life cycle assessment of H₂O electrolysis technologies

Hydrogen produced from H₂O electrolysis works as an energy carrier and helps to overcome the challenges of intermittent renewable energy sources. At present, no comprehensive environmental impact assessment is available for three commercially H₂O electrolysis technologies, namely solid oxide electrolysis cell (SOEC), polymer electrolyte membrane electrolysis cell (PEMEC), and alkaline electrolysis cell (AEC). The study aimed to provide potential environmental impacts of the electrolysis technologies based on life cycle assessment. Among the investigated 16 impact categories, the stage of critical material use of three H₂O electrolysis stacks was identified as the hotspot of environmental impacts. The critical materials were stainless steel and nickel from SOEC, platinum and iridium from PEMEC, and nickel from AEC. Life cycle impact results from PEMEC stack were much higher than these from SOEC and AEC stacks, while electricity played a more important role in the life cycle impact of hydrogen production. The sensitivity analysis indicated that the most effective approach to reducing potential impacts would be to reduce critical materials use on the current status of electrolysis technologies.