Key Takeaways & Executive Findings
- •• Compressed air effectively displaces brine from sediment voids in low-grade salt caverns, enabling CAES utilization. • A 0.5 MPa injection pressure in experiments corresponds to a 10.3 MPa operational lower limit in practice, validated by field data. • Sediment voidage in the Huai’an salt mine is approximately 46%, confirmed via air-brine interface theory. • The 'two injections and one discharge' mode outperforms 'one injection and one discharge' in both brine discharge volume and rate.
Abstract
Renewable energy storage technologies are critical for transitioning to sustainable energy systems, with salt caverns playing a significant role in large-scale solutions. In water-soluble mining of low-grade salt formations, insoluble impurities and interlayers detach during salt dissolution and accumulate as sediment at the cavern base, thereby reducing the storage capacity and economic viability of salt cavern gas storage (SCGS). This study investigates sediment formation mechanisms, void distribution, and voidage in the Huai’an low-grade salt mine, introducing a novel self-developed physical simulation device for two butted-well horizontal (TWH) caverns that replicates compressed air injection and brine discharge. Experiments comparing “one injection and one discharge” and “two injections and one discharge” modes revealed that (1) compressed air effectively displaces brine from sediment voids, (2) a 0.5 MPa injection pressure corresponds to a 10.3 MPa operational lower limit in practice, aligning with field data, and (3) sediment voidage is approximately 46%, validated via air-brine interface theory. The “two injections and one discharge” mode outperformed in both discharge volume and rate. Additionally, a mathematical model for brine displacement via compressed air was established. These results provide foundational insights for optimizing compressed air energy storage (CAES) in low-grade salt mines, advancing their role in renewable energy integration.
1. Introduction
The increasing global population and urbanization have had a negative impact on both people’s energy requirements and the environment [1]. It is estimated that the total population will reach around 10 billion by 2060, which will require an energy demand of nearly 770 EJ [2]. Fossil fuels, such as crude oil and natural gas, have been the dominant source of energy since 1870 and will continue to account for 55% of the energy supply in the future [3]. However, the burning of fossil fuels emits a large amount of carbon dioxide (CO2), which exacerbates the global greenhouse effect [4].
The average CO2 emissions between 2018 and 2023 amount to 32.16 Gt, which is still far from reaching the targets set in the Paris Agreement of 2015 [5]. Herein the utilization of large underground reservoirs, such as salt caverns, hard rock caverns, depleted gas reservoirs, and aquifers, for carbon capture, utilization, and storage (CCUS), has been employed as an effective approach to address carbon emissions [6–8]. However, due to its limited capacity, it accounts for only 0.1% of global emissions [9]. Therefore, to achieve China’s proposed carbon neutrality target by 2060, it is necessary to increase the proportion of renewable energy in total energy consumption and expand the deployment of energy storage technologies.
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Qihang Li, Wei Liu, Liangliang Jiang, Yiwen Ju, Aliakbar Hassanpouryouzband, Guimin Zhang, Xiangzhao Kong, Jun Xu (2025). Harnessing sediment voids of low-grade salt mines for compressed air energy storage: Experimental and theoretical insights. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.07.001
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
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Frequently Asked Questions
What is the significance of sediment voids in low-grade salt mines for CAES?
Sediment voids in low-grade salt mines provide additional storage space for compressed air energy storage (CAES). The study shows that compressed air can effectively displace brine from these voids, increasing the usable storage capacity and economic viability of salt cavern gas storage.
How was the sediment voidage measured in the study?
The sediment voidage was measured using a novel physical simulation device replicating two butted-well horizontal (TWH) caverns. Experiments compared different injection modes, and the voidage was validated via air-brine interface theory, yielding approximately 46%.
What are the key findings regarding injection pressure and operational limits?
The experiments revealed that a 0.5 MPa injection pressure in the laboratory corresponds to a 10.3 MPa operational lower limit in practical CAES applications, aligning with field data. This provides a scaling relationship for design and operation.
Which injection mode is more effective for brine discharge?
The 'two injections and one discharge' mode outperformed the 'one injection and one discharge' mode in both brine discharge volume and rate, suggesting a more efficient operational strategy for CAES in low-grade salt mines.
What is the broader impact of this research on renewable energy integration?
By enabling the use of low-grade salt mines for CAES, this research expands the potential for large-scale energy storage, which is crucial for integrating intermittent renewable energy sources like wind and solar into the grid, thereby supporting the transition to sustainable energy systems.
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