Sustainability of e-hydrogen carriers production: Techno-economic and life cycle perspectives in Saudi Arabia

Electrolytic hydrogen (e-hydrogen) is a promising renewable energy vector for global decarbonization efforts. However, its large-scale deployment requires efficient and scalable carrier pathways for storage and transport. This study provides a comprehensive techno-economic and environmental assessment of four hydrogen carriers (methanol, ammonia, methylcyclohexane (MCH), and liquid hydrogen (LH2)) produced via alkaline (AWE), proton exchange membrane (PEME), and solid oxide (SOEC) electrolyzers under Saudi Arabia's solar-rich conditions. Ammonia and methanol synthesized through AWE achieve the lowest levelized cost of hydrogen carrier (LCOHC), at 1.20 USD kg−1 and 1.48 USD kg−1, respectively. Across all systems, the hydrogen production cost, governed mainly by electrolyzer efficiency, stack cost, and solar CAPEX, dominates the economic performance. Future cost projections for 2030 and 2050 indicate that these pathways could become cost-competitive with fossil-based fuels. In terms of environmental assessment, methanol exhibits a net-negative global warming potential (−34 to −38 gCO2-eq MJ−1) through CO2 utilization. At the same time, ammonia exhibits the highest environmental burdens due to the intensive electricity consumption for compression and heating. Overall, these results highlight methanol and ammonia as the most promising hydrogen carriers for sustainable and large-scale energy transition in solar-dominant regions.