Green hydrogen production: A review of technologies, challenges, and hybrid system optimization

Green hydrogen produced via renewable-powered water electrolysis is a promising solution for decarbonizing energy systems. This review evaluates key production technologies, including alkaline, PEM, and solid oxide electrolysis, as well as biological methods such as fermentation and biophotolysis, highlighting trade-offs in efficiency, scalability, and sustainability. A mathematical model is proposed to optimize hybrid systems integrating photovoltaics, electrolyzers, fuel cells, hydrogen storage, and batteries, accounting for component degradation over a 25-year period. Environmental impacts, including water consumption and material scarcity, are analyzed alongside economic and systemic challenges. The study underscores the need for technological innovation, policy support, and integrated system design to accelerate the deployment of green hydrogen. • Comparative analysis of electrolysis and biological methods highlights trade-offs in efficiency, cost, and scalability. • Environmental and economic impacts of green hydrogen systems are evaluated, with emphasis on water use and safety. • A practical mathematical framework optimizes hybrid renewable-hydrogen systems. • Key challenges in adoption, cost, infrastructure, and material scarcity, are critically assessed.