Hydrogen from Seawater: an Environmental and Economic Evaluation of Aem and Pem Electrolysis Coupled with Advanced Desalination Systems

This research investigates the Global Warming Potential and the Levelized Cost of Hydrogen for Anion Exchange Membranes (AEM) and Proton Exchange Membranes (PEM) electrolysis plants fed by ultra-pure water produced from an innovative seawater purification system. The analyses are conducted by considering either the electricity supply from the Italian national grid or a 100% renewable energy mix. Values for Global Warming Potential (GWP) are equal to 22.3 kgCO2/kgH2 and 21.2 kgCO2/kgH2, respectively for PEM and AEM, when supplied with the Italian electrical grid, while a reduction of approximately 86% of impact is achievable in the case of renewable energy supply. The desalination unit contributes negligibly to the overall GWP. The Levelized Cost of Hydrogen (LCOH) was found to be equal to 6.33 €/kgH2 and 6.67 €/kgH2, respectively for PEM and AEM electrolysis. Most of the cost is associated to energy purchase during electrolysis, while water treatment accounts for only 0.20–0.65% of OPEX. These findings highlight the importance of integrating desalination with green hydrogen production to mitigate pressure on freshwater resources and advance the transition toward more sustainable energy systems. The study underscores the necessity of redefining hydrogen production strategies by prioritizing seawater sources, enhancing process efficiencies, and leveraging renewable energy inputs.