High variable renewable energy (VRE) systems require flexibility that can maintain adequacy during multi-day renewable shortfalls while absorbing periods of surplus generation. This study evaluates the role of geological hydrogen storage in future Great Britain electricity pathways using a time-resolved dispatch model that combines historical half-hourly generation and demand data with National Energy System Operator (NESO) aligned capacity, storage and electrified-demand scenarios for 2030–2040. The model explicitly represents electrolysis, underground hydrogen storage, hydrogen storage losses and hydrogen-to-power dispatch, and compares baseline and accelerated deployment pathways. Results show that accelerated hydrogen deployment has a stronger adequacy benefit than accelerated renewable and battery deployment alone. In 2030, all acceleration pathways reduce the unabated gas generation share from 4.61% to approximately 1%. However, by 2040, accelerated hydrogen and electrolysis can reduce the remaining peak unabated gas requirement to zero, whereas accelerated renewables and batteries still leave approximately 15 GW. Hydrogen-system performance is strongly governed by storage availability. Under NESO and Low storage scenarios, storage saturation causes up to 60 TWh of hydrogen production to remain unstored in 2035 across pathways. In contrast, the High storage scenario eliminates hydrogen not stored due to storage saturation, and stored hydrogen can exceed 190 TWh by 2040. These results show that geological hydrogen storage can materially improve adequacy in high-VRE power systems, but only when electrolysis, storage inventory and hydrogen-to-power capacity are scaled as a coordinated flexibility chain. While quantified here for Great Britain, the results are directly relevant to other countries pursuing high-VRE pathways and subsurface hydrogen storage for seasonal balancing and net-zero electricity-system operation.
Zhang et al. (Mon,) studied this question.