Technical and Economic Viability of Underground Hydrogen Storage

Considering the mismatch between the renewable source availability and energy demand, energy storage is increasingly vital for achieving a net-zero future. The daily/seasonal disparities produce a surplus of energy at specific moments. The question is how can this “excess” energy be stored? One promising solution is hydrogen. Conventional hydrogen storage relies on manufactured vessels. However, scaling the technology requires larger volumes to satisfy peak demands, enhance the reliability of renewable energies, and increase hydrogen reserves for future technology and infrastructure development. The optimal solution may involve leveraging the large volumes of underground reservoirs, like salt caverns and aquifers, while minimizing the surface area usage and avoiding the manufacturing and safety issues inherent to traditional methods. There is a clear literature gap regarding the critical aspects of underground hydrogen storage (UHS) technology. Thus, a comprehensive review of the latest developments is needed to identify these gaps and guide further R&D on the topic. This work provides a better understanding of the current situation of UHS and its future challenges. It reviews the literature published on UHS, evaluates the progress in the last decades, and discusses ongoing and carried-out projects, suggesting that the technology is technically and economically ready for today’s needs.