Mohamed G. Gado
This review article provides a comprehensive assessment of hydrogen production pathways and their economic viability, storage/transportation, and magnetic liquefaction. It also explores hydrogen deployment in cross-sectoral applications, including hard-to-abate industries (e.g., steel, fertilizers and refineries, cement, glass, and ceramics), mobility, power generation/grid stability, and building heating. It further discusses key limitations and future perspectives for large-scale hydrogen deployment. It is established that hydropower, geothermal, photovoltaic, and wind energy generally yield lower levelized costs of hydrogen than concentrated solar power systems, though methodological inconsistencies hinder cross-study comparability. Hydrogen storage continues to pose technical and economic challenges: compressed hydrogen is suitable for short-term use, whereas liquid hydrogen, ammonia, methanol, and liquid organic hydrogen carriers (LOHCs) offer distinct trade-offs in terms of energy density, efficiency, and infrastructure compatibility. Notably, pipeline-based compressed hydrogen transport is favored when accounting for life-cycle greenhouse gas emissions. Emerging magnetic refrigeration technologies show strong potential as next-generation hydrogen liquefaction methods, offering up to twice the efficiency of conventional cryogenic systems. Besides, ammonia leads as the most viable hydrogen carrier for long-haul transport, while LOHCs suit stationary applications. Overall, hydrogen plays a crucial role in decarbonizing key sectors, including heavy industry, transport, power, and heating, enabling a low-carbon and resilient global energy system.