Renewable hydrogen combined with large scale underground storage enables transportation of energy through time, balancing out the impacts of variable renewable energy production. While storing pure hydrogen in salt caverns has been practiced since the 70s in Europe, it has never been carried out anywhere in depleted fields or aquifers. Technical developments are needed to validate these two solutions. As subsurface technical feasibility studies for a future hydrogen storage in depleted field or aquifer will be site-specific, as for other geology related activities, HyStories will provide developments applicable to a wide range of possible future sites: the addition of H2-storage relevant characteristics in reservoir databases at European scale; reservoir and geochemical modelling for cases representative of European subsurface, and tests of this representativeness by comparing it with results obtained with real storage sites models; and lastly an extensive sampling and microbiological lab experiment programme to cover a variety of possible conditions. Complementarily, techno-economic feasibility studies will provide insights into underground hydrogen storage for decision makers in government and industry. Modelling of the European energy system will first define the demand for hydrogen storage. Environmental and Societal impact studies will be developed. For a given location and hydrogen storage demand, a high-level cost assessment for development of each of the competing geological storage options at that location will be estimated, and the sites will be ranked based on techno-economic criteria developed within the project. Finally, several case studies will enable consideration of the implementation of potential projects, notably by considering their economic interest. This will provide substantial insight into the suitability for implementing such storage across EU and enable the proposition of an implementation plan.

To meet the ambitious EC target of an 80% reduction in greenhouse gas emissions by 2050, CO2 Capture and Storage (CCS) needs to move rapidly towards full scale implementation with geological storage solutions both on and offshore. Onshore storage offers increased flexibility and reduced infrastructure and monitoring costs. Enabling onshore storage will support management of decarbonisation strategies at territory level while enhancing security of energy supply and local economic activities, and securing jobs across Europe. However, successful onshore storage also requires some unique technical and societal challenges to be overcome. ENOS will provide crucial advances to help foster onshore CO2 storage across Europe through: 1) Developing, testing and demonstrating in the field, under “real-life conditions”, key technologies specifically adapted to onshore storage. 2) Contributing to the creation of a favourable environment for onshore storage across Europe. The ENOS site portfolio will provide a great opportunity for demonstration of technologies for safe and environmentally sound storage at relevant scale. Best practices will be developed using experience gained from the field experiments with the participation of local stakeholders and the lay public. This will produce improved integrated research outcomes and increase stakeholder understanding and confidence in CO2 storage. In this improved framework, ENOS will catalyse new onshore pilot and demonstration projects in new locations and geological settings across Europe, taking into account the site-specific and local socio-economic context. By developing technologies from TRL4/5 to TRL6 across the storage lifecycle, feeding the resultant knowledge and experience into training and education and cooperating at the pan-European and global level, ENOS will have a decisive impact on innovation and build the confidence needed for enabling onshore CO2 storage in Europe.