Approaches to Sustainably Develop the Subsurface Potential for Storage and Disposal

To accomplish the energy transition, new methodologies and technical solutions for the storage of renewable energies need to be developed. A fundamental challenge lies in the fact that energy production from renewable sources (wind or sun) is subject to fluctuations that do not match the daily and/or seasonal swings of energy demand. Furthermore, the safe long-term disposal of environmentally hazardous nuclear and toxic waste in geological repositories is a social responsibility. With salt caverns and porous reservoirs, the subsurface offers a great potential for the storage of energy carriers (e.g. hydrogen, synthetic methane), potential energy (compressed energy) or thermal energy. Regardless of the time scale (daily seasonal or even over periods of up to 1 million years), barrier formations like salt, clay or crystalline rock ensure the necessary integrity and safety. This session aims to connect research, technical concepts and case studies addressing the geological boundary conditions of the various storage and repository options. The range of topics involve the description and assessment of the properties of storage and barrier formations and the relevant processes that occur during the operation and post-operation/abandonment phases of storages and repositories. These include the development of exploration methods, laboratory investigations to characterise rock properties at various scales, and the modelling-based analyses and simulations of coupled thermal, hydraulic, mechanical and (geo)chemical processes. An elementary part of these efforts is the incorporation of experience gained over the past decades to validate the models and methods used, as well as the linking of different scales of magnitude.