Green Hydrogen Production: Challenges and Opportunities of Water Electrolysis

The electrolysis of water is considered the most promising method for the clean production of renewable hydrogen. However, it faces challenges due to its unfavorable thermodynamics (H2O → H2 + 1/2O2; ΔG° = 237.24 kJ/mol; ΔH° = 285.83 kJ/mol) and its requirement for a significant amount of energy input (50-55 kWh of electricity per kilogram of H2). The success of this technology relies on the cost and type of electricity used, whether it is renewable or non-renewable.

Various renewable energy sources like wind, solar, and geothermal energy have been evaluated and demonstrated for large-scale water electrolysis. Despite its potential, in 2019, only 0.1% of global hydrogen production was achieved through water electrolysis. In the long term, hydrogen production through polymer electrolyte membrane water electrolysis (PEMEL) ('green') has the potential to become the least environmentally harmful technology in terms of climate change. However, challenges such as increasing water demand and the scarcity of materials need to be overcome to fully justify the implementation of a green hydrogen infrastructure.