• Carbon dioxide
• Carbon dioxide capture
• Carnot batteries
• Clean refrigerants fluids
• Compact heat exchangers
• Energy storage
• Renewable energies

This thesis is carried out within the CEEGS project, a Horizon Europe-funded initiative spanning a duration of three years, is dedicated to pioneering a cross-sectoral technological solution for the ongoing energy transition. The CEEGS project aims
to pioneer an innovative approach to energy storage, combining transcritical CO2 systems and geological storage. This groundbreaking technology exploits the thermodynamic properties of CO2 to implement Electrothermal Energy Storage (EES), intricately linked with geothermal energy extraction and CO2 sequestration in geological formations. In this system, CO2 is used as the working fluid, facilitating the storage of excess energy from wind or solar sources within geological formations. Simultaneously, geothermal heat is extracted from reservoirs and utilized to ensure that a portion of the injected CO2 becomes permanently sequestered in the geological formations. The technology not only enables large-scale energy storage but also enhances geothermal energy utilization while promoting the economic value and partial sequestration of CO2. The innovative CEEGS concept integrates an ESS with geological CO2 storage in a closed-loop configuration for energy storage and partial sequestration within a CO2. Carbon dioxide captured in a power plant or industrial facility, is used as the working fluid in the proposed thermodynamic cycle, storing renewable electrical energy on the surface and underground in a geological reservior.