European Geologist Journal 59

Carbon-based Energy Storage in the Horizon Europe CEEGS Project for the UN Sustainable Development Goals

 

by Filip Anđelković 1* and Dejan Radivojević1

1 University of Belgrade, Faculty of Mining and Geology, Department of Regional Geology, Kamenička 6, 11000 Belgrade, Serbia

Contact: filip.andjelkovic@rgf.rs

Abstract

New approaches to achieving net-zero emissions are necessary in order to successfully battle climate change. The CEEGS technology aims to contribute by integrating carbon capture and storage with electricity-generating technologies. The idea is to combine a renewable energy storage system which functions based on the cyclic injection of CO2 and discharge, with a CO2 storage system implemented in existing subsurface geological formations, along with heat extraction as a component of the cycle. The geological storage also includes sequestration, since a part of the injected CO2 would remain in the underground. The implementation of the CEEGS technology would significantly advance progress towards the UN Sustainable Development Goals, especially Affordable and Clean Energy (7), Industry, Innovation and Infrastructure (9), Sustainable Cities and Communities (11), and Climate Action (13).  

Cite as: Anđelković, F., & Radivojevic, D. (2025). Carbon-based Energy Storage in the Horizon Europe CEEGS Project for the UN Sustainable Development Goals. European Geologist, 59. https://doi.org/10.5281/zenodo.16441675

Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License.

  1. Introduction

In a drive to summarise the needs of the contemporary societies and steer the developmental push, the United Nations has created a set of guidelines, called the Sustainable Development Goals (SDG) [1]. This concept provides a framework that enables the identification of key human needs worldwide and outlines the path to their fulfilment. The 17 Goals cover various topics, including poverty, education, infrastructure, circular economy, and climate change [1,2].

Global economic issues dictate an environment in which traditional and renewable power sources are in a state of coexistence, with fossil fuels still being the dominant source [3]. Carbon emissions are on a rapid rise, following a temporary decline during the COVID-19 lockdown [4] (Figure 1). These circumstances highlight the need for innovative technologies that both reduce the harmfulness of existing practices and support the development of new, cleaner ones. Researchers from an array of European R&D institutions have devised a novel carbon-mitigating technological system: the CO2-based Electrothermal Energy and Geological Storage (CEEGS). This article presents the key components of the CEEGS technology and its potential impact on the Sustainable Development Goals.

Figure 1: Annual global carbon dioxide emissions from 1990 to 2023, measured in billion metric tons [4].

  1. An overview of the CEEGS technology

Capturing CO2 from traditional emitters and burying it in subsurface geological formations is not a new concept. It was first applied in 1972 for Enhanced Oil Recovery [5]. Similarly, electrothermal power storage units, named ‘Carnot batteries’ after Carnot’s law, have been under consideration for a long time. First proposed and patented by Fritz Marguerre more than a century ago [6], the interest in them has recently experienced revival [7]. CEEGS provides a new way to combine the two technologies into a single system, designed to remove CO2 from the atmosphere and use it as a working fluid for storing energy in times of excess and generating it during periods of increased demand [5, 8].

The working principles of the CEEGS system are based on the transcritical cycle, where CO2 transitions from subcritical to supercritical state when being pumped underground, and reverses this process when the system is producing [8, 9]. CO2 is captured from conventional sources (thermal power plants, heating plants, factories) and introduced into the cycle, eliminating it from the atmosphere [8]. Electricity from renewable sources is stored in electrothermal Carnot batteries [8-10], which operate on two levels: low-temperature (ice slurry) and high-temperature (liquid hot water) [9, 10]. Heat is extracted from the CO2 to power the electrothermal storage system.

Once underground, part of the total carbon dioxide is permanently sequestered in the formation, while the remainder is kept in the cycle as a working fluid [5, 11]. After the initial plume setup, during which CO2 is constantly being injected into the reservoir, the system is operated as follows: CO2 is produced for 6 hours, when it regains heat from the thermal storage and passes through a turbine, producing electricity; this is followed by 6 hours of rest; then, the fluid is pumped back into the reservoir for 6 hours; finally, the system is at rest for another 6 hours. This 24-hour cycle is repeated five more times, while the power demand is large [11]. A schematic diagram for the CEEGS process is shown in Figure 2.

Figure 2: Schematic diagram illustrating the main elements of the CEEGS process [9, 10].

Seven scenarios for the geological storage component have been considered [11]. They are grouped into two types, porous formations and salt cavities (Table 1).

Table 1: Possible geological scenarios considered in modelling [5].

POROUS FORMATIONS SALT CAVITIES
Deep saline aquifer (open) Single cavity
Deep saline aquifer (closed) Two cavities at different levels
Depleted hydrocarbon field  
Two saline aquifers at different levels  
Geothermal system  

Scenarios were tested by modelling in order to determine which options can operate the CEEGS system efficiently.  Porous formations were modelled using numerical methods based on data from real reservoirs, while salt cavities were assessed by semi-analytical modelling using laboratory data [5, 9, 11]. Three scenarios were confirmed to be suitable for CEEGS: open saline aquifers (at depths greater than 1850 m), carbonate geothermal system, and the single salt cavity. The depleted hydrocarbon field scenario must be tested for chemical reactions before a conclusion can be drawn about its suitability [5, 9, 11].

  1. Contribution to UN Sustainable Development Goals

In total, there are 17 Sustainable Development Goals, broadly covering various technological, societal, and economic problems the world is facing [1]. They are further divided into targets, which address specific problems to be solved. Moreover, indicators are specified to define the targets with qualitative or quantitative data [2]. The authors have identified four goals for which the CEEGS technology is directly relevant. Nevertheless, it is very likely that there are other goals that CEEGS also contributes to. A breakdown of the contribution to these four goals and their respective targets is presented in the following sections. Target formulations are cited after Barcéna et al. [2].

3.1. UN SDG 7: Ensure access to affordable, reliable, sustainable and modern energy for all

Target 7.2: By 2030, substantially increase the share of renewable energy in the global energy mix.

Answer: Since CEEGS uses electricity input from renewable sources, it supports their deployment.

Target 7.a: By 2030, enhance international cooperation to facilitate access to clean energy research and technology, including renewable energy, energy efficiency and advanced and cleaner fossil-fuel technology, and promote investment in energy infrastructure and clean energy technology.

Answer: By definition, CEEGS represents a fusion of advanced fossil-fuel and renewable technologies, since carbon-based sources are enabled to operate with mitigated carbon emissions, and the initial electricity input is from renewable sources. The broad social outreach campaign led by CEEGS representatives promotes wide interest and investment in advanced and clean technologies.

3.2. UN SDG 9: Build resilient infrastructure, promote inclusive and sustainable industrialisation and foster innovation

Target 9.4: By 2030, upgrade infrastructure and retrofit industries to make them sustainable, with increased resource-use efficiency and greater adoption of clean and environmentally sound technologies and industrial processes, with all countries taking action in accordance with their respective capabilities.

Answer: The implementation of CEEGS makes carbon-emitting industries more sustainable, as part of their emissions are removed from the atmosphere.

Target 9.5: Enhance scientific research, upgrade the technological capabilities of industrial sectors in all countries, in particular developing countries, including, by 2030, encouraging innovation and substantially increasing the number of research and development workers per 1 million people and public and private research and development spending.

Answer: The CEEGS Project actively encourages innovation, and by having a large contributor base with researchers from across Europe, helps increase the number of R&D personnel on the continent.

3.3. UN SDG 11: Make cities and human settlements inclusive, safe, resilient and sustainable

Target 11.b: By 2030, substantially increase the number of cities and human settlements adopting and implementing integrated policies and plans toward inclusion, resource efficiency, mitigation and adaptation to climate change, resilience to disasters, and develop and implement, in line with the Sendai Framework for Disaster Risk Reduction 2015-2030, holistic disaster risk management at all levels.

Answer: Although this is not a primary goal of CEEGS, it could be utilised to store and provide energy in times of natural disasters, such as hurricanes and floods, when conventional power sources are disrupted.

3.4. UN SDG 13: Take urgent action to combat climate change and its impacts

Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.

Answer: Same as for target 11.b.

Target 13.3: Improve education, awareness-raising, and human, and institutional capacity on climate change mitigation, adaptation, impact reduction and early warning.

Answer: CEEGS directly contributes to climate change mitigation by reducing carbon dioxide levels in the atmosphere, and encouraging use of renewable energy sources. In addition to that, by engaging with society at large, especially teenagers, through activities such as the Video Contest (https://ceegsproject.eu/2024/11/27/ceegs-video-contest), it raises awareness about the importance of clean technologies and climate adaptation.

  1. Discussion and conclusion

The CEEGS Project is set to include three phases:

  1. Defining theoretical principles and conducting simulations/modelling;
  2. Experimental verification;
  3. Social, economic, and sustainability assessments.

The second phase is already underway. It is apparent that the project is not only about developing the technical solutions to reduce atmospheric carbon dioxide levels, but also has a strong social assessment aspect, where the CEEGS team engages with the public to explore the varying opinions and promote interest in decarbonising technologies. Some issues that could be encountered include the absence of legal frameworks for CO2 capture and utilisation, and the general lack of public awareness on the very existence of such technologies. For example, the legislative corpus of Serbia, the authors’ home country, does not mention CCUS in any way, meaning there are currently no incentives for the development and deployment of CCUS projects. Furthermore, the public is uninformed about the possibilities of decarbonisation and could have irrational fears regarding the safety and ecological impact of CCUS. The third phase of the CEEGS project is designed to address these problems.

CEEGS is a highly scalable system, meaning it can be implemented in different capacities across different power and industrial systems. In conclusion, CEEGS is a highly promising technology, but it still requires significant research and testing before it is ready for full-scale implementation.

Author Contributions: Conceptualisation, F.A.; methodology, F.A.; software, F.A.; validation, F.A., and D.R.; formal analysis, F.A.; investigation, F.A.; resources, F.A. and D.R.; data curation, F.A. and D.R.; writing—original draft preparation, F.A.; writing—review and editing, D.R.; visualisation, F.A.; supervision, D.R.; project administration, F.A. and D.R. All authors have read and agreed to the published version of the manuscript.

Funding: This study was supported by the CEEGS (CO2-based Electrothermal Energy and Geological Storage) Project and the Ministry of Education, Science and Technological Development of the Republic of Serbia (No. 451-03-68/2022-14/200126).

Acknowledgments: The authors kindly acknowledge the European Federation of Geologists and the Serbian Geological Society for the opportunity to participate in the CEEGS Project.

Conflicts of Interest: The authors declare no conflict of interest.

References

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This article has been published in European Geologist Journal 59 – UN Sustainable Development Goals – where the geology lies