Definition of geological scenarios for the implementation of the CEEGS technology for underground energy storage and CO2 sequestration

The de-carbonization energy transition requires solutions to store energy on a large scale while reducing CO₂ emissions. The CEEGS project integrates the transcritical CO₂ cycle with geological storage and heat extraction, combining electrothermal storage and CO₂ sequestration. This work aims to identify the most suitable geological scenarios for future implementation and establish the fundamental criteria that must be met. To this end, the properties of different geological media were reviewed and evaluated, based on previous knowledge about geological CO2 and energy storage and geothermal applications. As a result, a preliminary set of criteria is proposed, based on thermodynamic and geochemical considerations and subsurface conditions. It constitutes a first approximation, which can be updated as the development of the CEEGS concept progresses.