Performance Investigation of a Solar-Driven Air Gap Membrane Distillation System Coupled with PEM Electrolysis for Sustainable Water and Hydrogen Production

Freshwater scarcity and the rising demand for clean energy standout as two ofthe most pressing global challenges, particularly in arid and semi-arid regions. To tackle these interconnected issues, this study explores an innovative approach utilizing a solar-powered Air Gap Membrane Distillation (AGMD) system integrated with a Proton Exchange Membrane (PEM) electrolyzer.This hybrid system is designed for the simultaneousproduction of freshwater and green hydrogen. The AGMD unit, driven by solar thermal power, generates high-purity distilled water suitable for both human consumption and use as feedwater in the PEM electrolyzer,which is powered by photovoltaic-generated electricity. An experimental setup,supported by a semi-empirical numerical model, was developed to evaluate how key operating factors—such as feedwater temperature, solar irradiation levels, membrane porosity, and air-gap thickness—affectthe system’s performance. The results reveal a strong correspondence between experimental observations and model predictions, validating the reliability of the proposed approach. Underpeak solar irradiation conditions, the system demonstrated the capacity to produce freshwater at rates of 4–5 litersperhour and generate hydrogen at a rate of approximately 0.04–0.06 Nm 3 h⁻ 1 under peak operating conditions. Sensitivity analysis highlights that feedwater temperature, membrane porosity, and air-gap thickness are critical parameters influencing vapor flux and overall system efficiency. Additionally, the combinedprocesses of desalination and hydrogen production enhance the utilization of renewable solar energy while ensuring consistent water quality and stable hydrogen output. In summary, this AGMD–PEM hybrid system offers substantialpromise as a sustainable solution for decentralized water and energy generation in regions with amplesolar resources but limited water availability.