Use of Hydrogen Energy Storage to Stabilize Solar Power Output With an Energy Efficiency Analysis for European Union Member Countries

ABSTRACT Seasonal energy storage as compressed hydrogen offers a potential solution to balance the power grid as intermittent renewable energy sources are expected to increase in capacity due to decarbonization efforts in developed countries. Public hourly electricity production data and hourly solar electricity production data from European Union member countries in 2025 were used for statistical analysis and optimization of hydrogen energy storage, focusing on the optimal share of solar electricity storage needed to achieve a constant energy output from solar power. Equipment sizing for hydrogen units was also estimated. Variations in the round‐trip efficiency of hydrogen energy storage were tested for Italy. The combination of wind and solar electricity production with hydrogen storage integration to produce a constant power output was studied for Germany. Although the round‐trip efficiency of hydrogen energy storage was assumed to be 40%, the mean overall energy efficiency of solar power utilization throughout 2025 for the 24 selected European Union member countries was 54.38%. The mean hydrogen storage capacity would be 57.4 Gg, which greatly exceeds the potential for geological hydrogen storage. Therefore, the main bottleneck for implementing this vision stems from the lack of long‐term hydrogen storage potential.