Scientific abstract:

Water electrolysis technologies to produce green hydrogen are discussed as a promising option for the decarbonization, diversification and security of supply of future energy systems. In the recent past, technological maturity of water electrolysis technologies has increased. Despite this progress, further technological improvements are expected in the long term. This study examines the trends in technology readiness, critical raw material use and electricity consumption of the three most mature water electrolysis technologies, polymer electrolyte membrane, alkaline, and solid oxide electrolysis cells, up to the year 2050. To date, there is a limited number of prospective Life Cycle Assessment (LCA) studies that consider all three technology options. In addition, changes in projected material requirements for electrolysis construction in general and potentially critical raw materials in particular are rarely used in existing LCA studies. Using LCA and trend extrapolation, this study provides new insights into the potential reduction in environmental impacts by technological improvements in electrolysis technologies. Historical, current, and projected data from the scientific literature are used to extrapolate these parameters. For critical raw materials and electricity consumption, trends are assessed using exponential trend curves. The assessment of the projected technology readiness shows that all three electrolysis technologies are expected to reach the highest level of technological maturity already in 2030. Regarding the demand for critical raw materials, there is data available in literature, especially for iridium, platinum, and titanium. The literature-based trend extrapolation suggests that demand for these materials could fall by more than 55% between 2020 and 2030. By 2050, the use of various critical raw materials is expected to decrease by more than 90% compared to today. The reductions in electricity demand for electrolysis technologies are much lower due to their physical limitations. Depending on the technology, the reduction in electricity demand between 2020 and 2050 ranges from 6 to 17%. Considering the impact of these changes on the environmental impact of hydrogen produced by wind power (green hydrogen), further reductions in the global warming potential of more than 20% are possible by 2050. With shares up to 90% the electricity demand clearly dominates the contributions to the global warming potential of hydrogen production in the years 2020 and 2050. The knowledge gained from the detailed technological and environmental assessment of the water electrolysis technologies and the insights into their future development can also be used as a starting point for criticality analyses and sustainability assessments.