Underground hydrogen storage : insights and actions to support the energy transition

Underground hydrogen storage is a fundamental requirement of any net zero energy system, which is likely to rely on the use of hydrogen as both an energy carrier for storing excess energy from renewable sources (e.g. solar, wind) and alternative fuel to decarbonise hard to abate sectors (e.g. shipping, freight, heavy industry). With the increasing penetration of renewable energy sources and as demand for hydrogen increases, the intermittency of supply poses significant challenges to balancing the energy system. Hydrogen, as a versatile energy carrier, offers a viable pathway to mitigate these challenges. Various underground storage technologies such as salt caverns, lined rock caverns and depleted hydrocarbon fields provide scalable and long-duration hydrogen storage options. These technologies, while requiring significant initial investment and specific geological conditions, offer the potential for largescale long duration storage capacities. However, there are still considerable knowledge gaps in how and where such large-scale storage can be achieved.