Lower carbon power systems through longer duration energy storage: hydrogen in depleted uranium (HyDUS)

‘Green hydrogen’ derived from renewable energy sources (RES) is gaining attention as a carbon-neutral energy carrier for power, heat, and transport applications. It offers a longer-duration energy storage (LODES) solution by storing excess energy from solar PV and wind sources, mitigating power waste during low-demand-surplus-energy periods. This becomes crucial during prolonged seasonal variations such as dunkelflaute/anticyclone events particularly challenging for weather-sensitive power grids. As RES shares grow and electrification in heat and transport sectors increases, efficient LODES technologies are needed to enhance network resilience, with hydrogen storage emerging as a promising solution. However, integrating hydrogen- based systems, including electrolyzers, fuel cells, and hydrogen storage facilities, presents challenges due to the intricate coupling of multiple energy vectors. This work presents a comprehensive hydrogen energy storage system (HESS) modelling framework suitable for LODES applications in a RES-dominated power system. The proposed HESS model integrates an electrolyzer as a load and a fuel cell as a generator within a single facility, featuring an innovative hydrogen-depleted uranium storage (HyDUS) bed system that uses repurposed metallic DU as the ‘host’ material for efficient hydrogen storage. This model accounts for nonlinear physical/chemical characteristics, and operational constraints of individual components, including power capabilities, ramping limitations, and converter power transfer constraints. Emphasizing device-level features, the proposed HESS is evaluated using case studies based on the UK power grids.