Behnous, Dounya , Carneiro, Julio , CARRO PAULETE, ANDRES, Canteli, Paula , Chacartegui, Ricardo , Crespo, Jesus G. , Tyrologou, Pavlos , Koukouzas, Nikolaos
No
J. Energy Storage
Article
Científica
20/12/2025
001599804800001
The CO2-based Electrothermal Energy and Geological Storage (CEEGS) system integrates energy storage with CO2 sequestration by storing excess renewable energy as supercritical CO2, which is back-produced for power generation. This study investigates reservoir (porosity, permeability, relative permeability, heterogeneity, anisotropy) and operational (injection rates, shut-in periods) parameters to maximise CO2 saturation near the wellbore and minimise water co-production, critical for the energy storage capacity and operation of the surface transcritical CO2 power cycles. Using CMG-STARS and CMOST-AI, we conducted a sensitivity analysis across injection rates (5-100 kg/s), porosity (0.05-0.25), permeability (10-1000 mD), and heterogeneity (C.V. 0.1-1.5). Results show that injection rates of 30-40 kg/s, porosity of 0.05-0.15, and low heterogeneity (C.V. <0.25) achieve gas saturation up o 76 % with water production below 0.1 kg/s. Shut-in periods should not exceed 3 months to limit saturation losses. These findings provide a robust framework for optimising the CEEGS site selection and operation definition, ensuring supercritical CO2 back production with adequate characteristics for efficient energy storage and operation.
CEEGS; Energy storage; Water production; Reservoir simulation; CEEGS; Supercritical CO2; Energy storage; Water production; Reservoir simulation