Techno-economic-environmental analysis of hydrogen production technologies using urban and industrial wastewater

Green hydrogen production from wastewater offers a dual benefit of valorizing waste streams while supporting the transition to low-carbon energy systems. However, comparative evaluations of electrolyser technologies using wastewater as feedstock remain limited, particularly when considering technical, economic, and environmental criteria jointly. This study assesses four electrolysis technologies, Alkaline Electrolysis (AEL), Proton Exchange Membrane (PEM), Solid Oxide Electrolysis Cell (SOEC), and Microbial Electrolysis Cell (MEC), using both urban and industrial wastewater. A systematic literature review covering the past 15 years, conducted following the PRISMA methodology, identified 38 relevant studies, with additional sources included to fill gaps in economic and environmental data. Technical performance, including energy consumption (kWh∙Nm −3 H2 ), system efficiency (%), and hydrogen production rate (kg H2 ∙kW −1 ∙y −1 ), was evaluated alongside economic (CAPEX, OPEX, levelized cost of H 2 ) and environmental indicators (global warming, acidification, and eutrophication potentials) through multi-criteria decision analysis (MCDA). For urban wastewater, SOEC ranked highest (normalized MCDA score of 73 %), followed by PEM (59 %), AEL (57 %), and MEC (38 %). For industrial wastewater, MCDA indicated that MEC performed better (89 %), even though SOEC presented itself as the most balanced economically and environmentally (83 %), while MEC ranked lowest under these criteria (35 %). Sensitivity analyses confirmed the robustness of such performances. Overall, SOEC emerges as the most promising technology for integrated wastewater-to-hydrogen systems, with AEL and PEM as viable short-term alternatives. MEC offers unique potential for combined treatment and hydrogen production, despite current technical and economic limitations.