{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T11:26:54Z","timestamp":1766748414990,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,1,27]],"date-time":"2025-01-27T00:00:00Z","timestamp":1737936000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"European Union","doi-asserted-by":"publisher","award":["101084376"],"award-info":[{"award-number":["101084376"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>The goal to reduce greenhouse gas emissions necessitates the increase in RES utilization. To accomplish this goal, energy storage solutions are required. This study investigates the performance of an electrothermal energy storage system, the CEEGS, which consists of an above-surface energy storage system and a below-surface geological system. The focus is set initially on the analysis of the above-surface system to gain insight into its operation. Then, steady-state optimization is utilized to identify the operating conditions that maximize the system performance, before investigating the below-surface system integration and the effect that the geological conditions have on system performance. For the above-surface system, efficiency (\u03b7R-T) up to 46.89% is calculated. For systems integrated with CO2 geological storage, two case studies are examined, presenting higher \u03b7R-T compared to the above-surface system (Case study 1: 50.37%, Case study 2: 67.39%). The optimal \u03b7R-T for Case study 2 is achieved for higher injection\/production pressures and temperatures conditions and minimal \u0394P and \u0394T between injection and production. In conclusion, it is the selection of the geological storage conditions that contribute the most to the optimal \u03b7R-T; thus, the selection of the appropriate geological storage formation is imperative.<\/jats:p>","DOI":"10.3390\/en18030601","type":"journal-article","created":{"date-parts":[[2025,1,27]],"date-time":"2025-01-27T11:38:49Z","timestamp":1737977929000},"page":"601","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Analysis and Evaluation of a TCO2 Electrothermal Energy Storage System with Integration of CO2 Geological Storage"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-5949-4006","authenticated-orcid":false,"given":"Aristeidis","family":"Stoikos","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece"},{"name":"Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas, 57001 Thessaloniki, Greece"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5096-2476","authenticated-orcid":false,"given":"Alexios-Spyridon","family":"Kyriakides","sequence":"additional","affiliation":[{"name":"Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas, 57001 Thessaloniki, Greece"}]},{"given":"J\u00falio","family":"Carneiro","sequence":"additional","affiliation":[{"name":"ICT\/IIFA, Geosciences Department, Universidade de \u00c9vora, R. Rom\u00e3o Ramalho 59, 7000-671 \u00c9vora, Portugal"},{"name":"Converge! Lda, Parque de Ci\u00eancia e Tecnologia do Alentejo, R. Lu\u00eds Adelino da Fonseca, Lt 1A, 7005-841 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7504-7450","authenticated-orcid":false,"given":"Dounya","family":"Behnous","sequence":"additional","affiliation":[{"name":"Converge! Lda, Parque de Ci\u00eancia e Tecnologia do Alentejo, R. Lu\u00eds Adelino da Fonseca, Lt 1A, 7005-841 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6708-9113","authenticated-orcid":false,"given":"Georgios","family":"Gravanis","sequence":"additional","affiliation":[{"name":"Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas, 57001 Thessaloniki, Greece"},{"name":"Department of Information and Electronic Engineering, International Hellenic University, 57001 Thessaloniki, Greece"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3466-1873","authenticated-orcid":false,"given":"Ioannis N.","family":"Tsimpanogiannis","sequence":"additional","affiliation":[{"name":"Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas, 57001 Thessaloniki, Greece"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4077-4284","authenticated-orcid":false,"given":"Panos","family":"Seferlis","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9212-1712","authenticated-orcid":false,"given":"Spyros","family":"Voutetakis","sequence":"additional","affiliation":[{"name":"Chemical Process and Energy Resources Institute, Centre for Research and Technology-Hellas, 57001 Thessaloniki, Greece"}]}],"member":"1968","published-online":{"date-parts":[[2025,1,27]]},"reference":[{"key":"ref_1","unstructured":"United Nations (2024, September 09). Paris Agreement. Available online: https:\/\/unfccc.int\/sites\/default\/files\/english_paris_agreement.pdf."},{"key":"ref_2","unstructured":"International Energy Agency (2024, September 09). World Energy Outlook. Available online: https:\/\/www.iea.org\/reports\/world-energy-outlook-2023."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"101047","DOI":"10.1016\/j.est.2019.101047","article-title":"A review of energy storage types, applications and recent developments","volume":"27","author":"Rosen","year":"2020","journal-title":"J. Energy Storage"},{"key":"ref_4","unstructured":"International Energy Agency (2024, September 10). Renewables 2021 Analysis and Forecasts to 2026. Available online: https:\/\/www.iea.org\/reports\/renewables-2021."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"105782","DOI":"10.1016\/j.est.2022.105782","article-title":"Carnot Battery development: A review on system performance, applications and commercial state-of-the-art","volume":"55","author":"Vecchi","year":"2022","journal-title":"J. Energy Storage"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"116650","DOI":"10.1016\/j.apenergy.2021.116650","article-title":"Carnot battery: Simulation and design of a reversible heat pump-organic Rankine cycle pilot plant","volume":"288","author":"Eppinger","year":"2021","journal-title":"Appl. Energy"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"112530","DOI":"10.1016\/j.enconman.2020.112530","article-title":"Multi-criteria investigation of a pumped thermal electricity storage (PTES) system with thermal integration and sensible heat storage","volume":"208","author":"Frate","year":"2020","journal-title":"Energy Convers. Manag."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1016\/j.rser.2019.03.056","article-title":"Cyclic transient behavior of the Joule\u2013Brayton based pumped heat electricity storage: Modeling and analysis","volume":"111","author":"Wang","year":"2019","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"103663","DOI":"10.1016\/j.est.2021.103663","article-title":"Analytic optimization of Joule\u2013Brayton cycle-based pumped thermal electricity storage system","volume":"47","author":"Wang","year":"2022","journal-title":"J. Energy Storage"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"108865","DOI":"10.1016\/j.est.2023.108865","article-title":"Operating performance of a Joule-Brayton pumped thermal energy storage system integrated with a concentrated solar power plant","volume":"73","author":"Cascetta","year":"2023","journal-title":"J. Energy Storage"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1016\/j.renene.2022.01.017","article-title":"Thermo-economic assessments of pumped-thermal electricity storage systems employing sensible heat storage materials","volume":"186","author":"Zhao","year":"2022","journal-title":"Renew. Energy"},{"key":"ref_12","unstructured":"Cahn, R.P. (1978). Thermal Energy Storage by Means of Reversible Heat Pumping. (4,089,744), U.S. Patent."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1016\/j.energy.2012.03.013","article-title":"Electrothermal energy storage with transcritical CO2 cycles","volume":"45","author":"Hemrle","year":"2012","journal-title":"Energy"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1016\/j.energy.2012.03.031","article-title":"Conceptual design of a thermo-electrical energy storage system based on heat integration of thermodynamic cycles\u2014Part A: Methodology and base case","volume":"45","author":"Morandin","year":"2012","journal-title":"Energy"},{"key":"ref_15","first-page":"444","article-title":"Transcritical Carbon Dioxide Charge-Discharge Energy Storage with Integration of Solar Energy","volume":"7","author":"Fernandez","year":"2019","journal-title":"J. Sustain. Dev. Energy Water Environ. Syst."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"121665","DOI":"10.1016\/j.energy.2021.121665","article-title":"Integration of energy storage systems based on transcritical CO2: Concept of CO2 based electrothermal energy and geological storage","volume":"238","author":"Carro","year":"2022","journal-title":"Energy"},{"key":"ref_17","unstructured":"(2024, September 18). CEEGS Project. Available online: https:\/\/ceegsproject.eu\/."},{"key":"ref_18","first-page":"505","article-title":"Modelling and Evaluation of CO2-based Electrothermal Energy Storage System","volume":"103","author":"Kyriakides","year":"2023","journal-title":"Chem. Eng. Trans."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"124028","DOI":"10.1016\/j.applthermaleng.2024.124028","article-title":"Assessment of carbon dioxide transcritical cycles for electrothermal energy storage with geological storage in salt cavities","volume":"255","author":"Carro","year":"2024","journal-title":"Appl. Therm. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Unger, S., Fogel, S., Sch\u00fctz, P., Chacartegui, R.R., Carro, A., Carneiro, J., and Hampel, U. (2024, January 24\u201328). The sCO2 Facility CARBOSOLA: Design, Purpose and Use for Investigating Geological Energy Storage Cycles. Proceedings of the ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition Volume 11: Supercritical CO2, London, UK.","DOI":"10.1115\/GT2024-122133"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1016\/j.enconman.2018.12.031","article-title":"Comparative analysis of air and CO2 as working fluids for compressed and liquefied gas energy storage technologies","volume":"181","author":"Liu","year":"2019","journal-title":"Energy Convers. Manag."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/j.enconman.2016.08.096","article-title":"Thermodynamic analysis of a compressed carbon dioxide energy storage system using two saline aquifers at different depths as storage reservoirs","volume":"127","author":"Liu","year":"2016","journal-title":"Energy Convers. Manag."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"120985","DOI":"10.1016\/j.apenergy.2023.120985","article-title":"Dynamic operating characteristics of a compressed CO2 energy storage system","volume":"341","author":"Huang","year":"2023","journal-title":"Appl. Energy"},{"key":"ref_24","unstructured":"Brown, D.W. (2000, January 24\u201326). A hot dry rock geothermal energy concept utilizing supercritical CO2 instead of water. Proceedings of the SGP-TR-165 Proceedings 25th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA, USA."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1016\/j.geothermics.2006.08.002","article-title":"Enhanced geothermal system (EGS) using CO2 as working fluid\u2014A novel approach for generating renewable energy with simultaneous sequestration of carbon","volume":"35","author":"Pruess","year":"2006","journal-title":"Geothermics"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1446","DOI":"10.1016\/j.enconman.2007.12.029","article-title":"On production behavior of enhanced geothermal systems with CO2 as working fluid","volume":"49","author":"Pruess","year":"2008","journal-title":"Energy Convers. Manag."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1021\/ef800601z","article-title":"CO2 thermosiphon for competitive geothermal power generation","volume":"23","author":"Atrens","year":"2009","journal-title":"Energy Fuels"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2206","DOI":"10.1016\/j.egypro.2011.02.108","article-title":"Coupling carbon dioxide sequestration with geothermal energy capture in naturally permeable, porous geologic formations: Implications for CO2 sequestration","volume":"4","author":"Randolph","year":"2011","journal-title":"Energy Procedia"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"10401","DOI":"10.1029\/2011GL047265","article-title":"Combining geothermal energy capture with geologic carbon dioxide sequestration","volume":"38","author":"Randolph","year":"2011","journal-title":"Geophys. Res. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"115900","DOI":"10.1016\/j.energy.2019.115900","article-title":"Supercritical CO2 Brayton cycle: A state-of-the-art review","volume":"189","author":"Liu","year":"2019","journal-title":"Energy"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.ijggc.2016.11.020","article-title":"Cost and performance of some carbon capture technology options for producing different quality CO2 product streams","volume":"57","author":"Porter","year":"2017","journal-title":"Int. J. Greenh. Gas Control"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2563","DOI":"10.1016\/j.rser.2017.06.064","article-title":"A systematic review of key challenges of CO2 transport via pipelines","volume":"81","author":"Onyebuchi","year":"2018","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_33","unstructured":"Carro, A., and Chacartegui, R. (2024, November 22). The Horizon Europe CEEGS Project: Deliverable 3.1\u2014CEEGS Cycle, Relevant System Characterization. University of Seville. Available online: https:\/\/ceegsproject.eu\/technical-reports\/."},{"key":"ref_34","unstructured":"Carneiro, J., and Behnous, B. (2024, November 22). The Horizon Europe CEEGS Project: Deliverable 2.1\u2014Geological Scenarios and Their Characteristics. \u00c9vora, Portugal. Available online: https:\/\/ceegsproject.eu\/technical-reports\/."},{"key":"ref_35","unstructured":"Siemens Process Systems Engineering Limited (2024, August 27). gPROMS Process 2023.1.0. Available online: https:\/\/www.siemens.com\/global\/en\/products\/automation\/industry-software\/gproms-digital-process-design-and-operations\/gproms-modelling-environments\/gproms-process.html."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3032","DOI":"10.1021\/je300655b","article-title":"The GERG-2008 Wide-Range Equation of State for Natural Gases and Other Mixtures: An Expansion of GERG-2004","volume":"57","author":"Kunz","year":"2012","journal-title":"J. Chem. Eng. Data"},{"key":"ref_37","unstructured":"Klimeck, R. (2000). Entwicklung Einer Fundamentalgleichung f\u00fcr Erdgase f\u00fcr das Gas- und Fl\u00fcssigkeitsgebiet Sowie das Phasengleichgewicht. [Ph.D. Dissertation, Fakult\u00e4t f\u00fcr Maschinenbau, Ruhr-Universit\u00e4t Bochum]."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1063\/1.1461829","article-title":"The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use","volume":"31","author":"Wagner","year":"2002","journal-title":"J. Phys. Chem. Ref. Data"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1021\/i160057a011","article-title":"A New Two-Constant Equation of State","volume":"15","author":"Peng","year":"1976","journal-title":"Ind. Eng. Chem. Fundam."}],"container-title":["Energies"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1073\/18\/3\/601\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T10:37:18Z","timestamp":1759919838000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1073\/18\/3\/601"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,1,27]]},"references-count":39,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,2]]}},"alternative-id":["en18030601"],"URL":"https:\/\/doi.org\/10.3390\/en18030601","relation":{},"ISSN":["1996-1073"],"issn-type":[{"type":"electronic","value":"1996-1073"}],"subject":[],"published":{"date-parts":[[2025,1,27]]}}}