Harnessing Renewable Energy for Hydrogen Production: Advances, Challenges, and Opportunities

This review examines renewable hydrogen production as a key strategy for a sustainable energy transition, analyzing solar, wind, biomass, geothermal, tidal, and ocean energy sources. Technological milestones include 0.67% solar-to-hydrogen efficiency in tandem photoelectrochemical cells, 61.9 N·m3/kg hydrogen from biomass gasification, and 38 million tons/year projected wind-based hydrogen by 2030. Novel ocean thermal energy conversion (OTEC) systems with proton exchange membrane (PEM) electrolysis yield 1.349 kg/h, while microbial electrolysis achieves a 14.75 A/m2 current density and 71.22% recovery. Photofermentation produces up to 7.0 mol H2/mol hexose, and thermochemical cycles reach 93.5% efficiency. Economic projections suggest hydrogen costs will fall to $1–2/kg by 2050. Environmental analyses show 70–90% emission reductions versus conventional methods. Integration with smart grids has achieved over 60% efficiency in hybrid systems. While promising, further optimization is needed in efficiency, infrastructure, and cost. This analysis supports researchers, industry leaders, and policymakers in advancing hydrogen as a clean energy cornerstone.