A Global Review of Blue and Green Hydrogen Fuel Production Technologies, Trends and Future Outlook to 2050

Hydrogen is emerging as a key energy carrier in the transition to a low-carbon economy. This study reviews blue and green hydrogen, analysing their production technologies, environmental impacts, economic viability and global deployment trends. Blue hydrogen, derived from natural gas, coal or biomass with carbon capture, utilisation and storage, offers a transitional pathway by reducing emissions relative to unabated fossil routes, but its benefits depend on high CO₂ capture efficiencies and strict methane leakage control. Green hydrogen, produced via renewable-powered electrolysis and advanced thermochemical, photochemical and photoelectrochemical methods, represents the most sustainable long-term solution, though it is currently limited by cost and scale. This comparative assessment shows that green hydrogen’s production emissions, in the range of 0.67 kgCO-eq/kgH to 1.74 kgCO₂-eq/kgH₂, are substantially lower than those of blue hydrogen, in the range of 1.21 kgCO₂-eq/kgH2 to 4.56 kgCO₂-eq/kgH₂, reinforcing its alignment with climate neutrality goals. Global production remains below 1% from low-emission sources, yet momentum is growing, with renewable-rich regions investing in large-scale electrolysers. A long short-term memory forecast suggests that blue hydrogen will dominate in the short term, but green hydrogen will surpass it around 2042. Together, both pathways are essential, blue hydrogen as a bridging option and green hydrogen as the foundation of a sustainable hydrogen economy.