Regional deployment analyses of energy storage based on geological storage of CO₂

The storage and reutilization of renewable energy through the CO₂-based Electrothermal Energy and Geological Storage (CEEGS) system is based on a reversible heat pump cycle and large geological subsurface stores for CO₂-storage. The storage concept is based on transcritical CO₂-cycles, which comprise a heat pump for the charging phase and a thermal engine for the discharging phase. During the charging process, renewable electrical energy is used to compress the working fluid CO₂ and the resulting compression heat is stored as thermal energy (sensible heat on the high-temperature side). In the discharge phase, the previously stored thermal energy is utilised to generate electricity (expansion cooling and storage as latent heat on the low-temperature side). The subsurface store is the central interface that connects the two processes (charge and discharge cycles) with each other. The compressed CO₂ (charging cycle) is stored in a suitable subsurface store (salt cavities or porous aquifers) and is retrieved or back-produced from the reservoir at high pressures (discharge cycle) when required. Renewable energy inputs to the CEEGS system are expected to be characterised by significant daily and seasonal fluctuations for both PV and wind production. As a consequence, the CEEGS system and its components, particularly its storage components, must be designed and appropriately sized to accommodate the seasonal storage of these fluctuating inputs. Here, a particular focus lies in the assessment of specific implementations of the CEEGS energy storage concept within regional and national infrastructure and energy systems. Specific regional deployment scenarios for different European regions are studied via multi-criteria decision analyses (MCDA) employing a large variety of georeferenced criteria and parameters relevant to the successful deployment of future CEEGS systems.

Fields of work

• synthesis of methodological frameworks for multi-criteria decision analyses (MCDA)
• collection and processing of relevant georeferenced information (technical, social, environmental, and economic domains)
• basic software development for MCDA and GIS data processing
• determination of optimal deployment clusters for the CEEGS technology
• collection of site-specific information (subsurface conditions, localised renewable time series)

Publications

• Canteli, P.; García-Crespo, J.; Fogel, S.; Unger, S.
  Deliverable 6.2 - Transversal intersectoral decarbonisation as GHG balance
  The Horizon Europe CEEGS project, IGME-CSIC, HZDR, (2024)
• Fogel, S.; Stoikos, A.; Carro, A.; Kyriakides, A.-S.; Tsimpanogiannis, I.N.; Chacartegui, R.; Unger, S.; Nanaki, E.
  Deliverable 4.4 – Potential for seasonal storage of energy
  The Horizon Europe CEEGS project, HZDR, USE, CERTH, HELPE, (2025)

Funding

The Horizon Europe CEEGS project (HORIZON, GA: 101084376, 2022-2025).
The authors are responsible for the presented content.