Overview of the Hystories Project
The Hystories project, funded by the European Union, explored underground hydrogen storage in Europe from January 1, 2021, to June 30, 2023. Led by Geostock, it involved key partners across Europe and gathered geological data from 23 countries. The project focused on salt caverns and porous media (depleted liquid or gaseous hydrocarbon reservoirs, saline aquifers).
The current industrial experience of pure hydrogen storage is limited, with only a few projects in Europe and the United States. While the storage of town gas (a mixture containing hydrogen) in porous media has a historical precedent, the storage of pure hydrogen presents new challenges, particularly due to its reactivity, its ability to embrittle steels, and its low viscosity and volumetric energy density.
The main objectives of the Hystories project were to bring technical developments to large-scale renewable hydrogen storage in depleted fields or aquifers and to assess how underground hydrogen storage could facilitate the transition to a CO2 emission-neutral energy system in the EU by 2050.
The project identified potential underground hydrogen storage sites in porous media and estimated their total hydrogen storage capacity at 6,850 TWh (19,000 TWh including offshore sites) in the EU and neighboring countries. A risk analysis method associated with microbial activity in future underground hydrogen storage was proposed, and hydrogen consumption was modeled, with results showing 0.06% at the laboratory scale and 0.004% at the storage scale after five seasonal injection and withdrawal cycles of hydrogen. A dozen common steel grades for oil tubing were tested in a hydrogen environment, and recommendations were issued on the type of steel to be used in storage.
In conclusion, underground hydrogen storage has significant potential to contribute to the decarbonization of energy networks and societies, especially in Europe. Storage in salt caverns is considered technically mature. Storage in depleted fields or aquifers has no major identified technical impediment, although questions remain regarding the quality of the gas released and potential treatment costs before it can be re-injected into a hydrogen distribution network. The project also highlighted the importance of the regulatory framework and business models for the deployment of storage sites, as well as the need for further investigation into cost estimation and the role of underground hydrogen storage in the energy value chain.