Critical technologies in the construction of underground artificial chamber for compressed air energy storage systems
Abstract
Compressed air energy storage (CAES) has emerged as a grid-scale energy storage linchpin, providing diurnal-to-seasonal timescale energy buffering for renewable power integration. Diverging from conventional salt cavern-dependent approaches, artificial cavern-based CAES unlocks geographical adaptability through engineered underground containment. This study systematically reviews critical technologies in chamber construction, including site selection, structural design, excavation methods, and post-construction evaluation. Site selection employs a multi-criteria matrix that combines geological and environmental factors. Structural design integrates spatial layout, burial depth, sealing system, and component compatibility to ensure chamber stability. Excavation prioritizes controlled blasting for homogeneous rock, while a tunnel boring machine is deployed in fractured zones to preserve integrity. Post-construction assessments validate load-bearing capacity, sealing performance, and operational readiness, supported by data-driven maintenance strategies. Ongoing challenges include site-specific geological risks, sealing system durability under cyclic loading, equipment integration, field-scale validation, standardization gaps, and cost-efficiency optimization. These innovations will establish best practices for building large-scale, high-efficiency CAES plants with ultra-long duration and grid resilience, accelerating the transition to carbon-neutral power systems.
Highlights
Propose a compressed air energy storage chamber construction framework: integrating multicriteria site selection, stability-optimized structural design, and adaptive excavation with data-driven post-evaluation.
Identify critical challenges: site-specific geological risks, field-scale validation needs, and standardization roadmaps to accelerate carbon-neutral energy transitions.
1 INTRODUCTION
To achieve the “dual carbon” goals, China is rapidly transitioning its energy structure toward renewable sources. Building a new power system centered on wind and solar energy is crucial for this transformation. However, the inherent intermittency and instability of renewable generation create significant temporal and spatial mismatches between supply and demand. New energy storage technologies are vital for enhancing grid stability, increasing renewable consumption, and enabling peak load shifting within this evolving system (Gao et al., 2023; Wan, Yang, et al., 2023). Among emerging large-scale storage solutions, compressed air energy storage (CAES) stands out due to its large capacity, long lifespan, high safety, flexible siting, and efficiency, positioning it as a key technology alongside pumped hydro for stabilizing renewable supply and grid management (Budt et al., 2023). In 1978, Germany established the world's first commercial CAES power station, the Huntorf Power Station, using a salt cavern for gas storage, with an installed capacity of 290 MW and an energy storage efficiency of about 42% (Rabi et al., 2023). In 1991, the United States built the McIntosh power station, also using a salt cavern, with an installed capacity of 110 MW and an efficiency of 54%, but still relying on natural gas for afterburning. By 2018, Switzerland tested CAES with thermal insulation, using mountain tunnels for gas storage, but faced gas leakage issues, hindering full commercialization. In 2019, Canada launched the Goderich project, the first 10 MW salt cavern gas storage project using non-afterburning technology, demonstrating efficient heat recovery (Safaei et al., 2013). However, uneven salt cavern distribution and immature artificial gas storage sealing technology limited system efficiency. Currently, European and American countries are accelerating research on non-afterburning, isothermal CAES, and multi-energy coupling systems (e.g., combining with gas turbines and renewable energy), innovating storage locations. Germany and Japan are exploring hard caverns and abandoned mines for gas storage. Research has expanded from single energy storage to thermal-electric synergy (e.g., organic rankine cycle waste heat power generation) and low-carbon solutions (e.g., hydrogen energy production) (Lund & Salgi, 2009).
China's CAES research, though initiated relatively late, has advanced rapidly in recent years with strong policy support. The technology has progressed from kilowatt-scale pilots to megawatt and hundred-megawatt levels, marked by the recent successful grid connection of 300 MW power stations. Multiple demonstration projects now exist across the country, utilizing not only salt caverns but also artificial chambers and steel pipelines, reflecting diversification in gas storage technologies. Unlike geology-dependent large-scale storage systems (e.g., salt caverns, mines, and aquifers), artificial chamber CAES (AC-CAES) offers superior site selection flexibility and broader applicability, making it optimal for regions with limited geological resources (Jiang et al., 2025; Ji, Wan, et al., 2024). Globally, countries like the United States, Japan, and South Korea have explored AC-CAES technically and in pilots. China has also significantly increased investment, exemplified by the 300 MW Jiuquan AC-CAES demonstration project (using artificial caverns and non-supplementary combustion). However, key technological gaps hinder large-scale commercialization: challenges in cavern construction under cyclic thermo-mechanical loads, durable high-pressure sealing materials, standardized design methods, seamless underground-ground system integration, and specialized engineering talent cultivation. This study elucidates the working principles and technological status of AC-CAES systems, analyzes the key technologies in chamber construction, proposes challenges and corresponding solutions for large-scale industrialization, and discusses future development directions, aiming to provide insights and references for the industrial application of AC-CAES.
2 TECHNICAL PRINCIPLES AND DEVELOPMENT STATUS
2.1 CAES technical principles
1.
Compression (energy input): The primary equipment used is an air compressor. During energy input, external electricity powers the compressor, drawing and compressing ambient air into high-temperature, high-pressure air. This converts electrical energy into thermal and potential energy, storing heat in a heat storage unit and gas pressure in an energy storage facility.
2.
Accumulation (energy storage): Gas storage devices, such as ground tanks and underground storage spaces, are essential for energy storage. These sealed spaces can store compressed gas without leakage, maintain their thermodynamic integrity within specified operational cycles, and minimize energy dissipation. This process achieves long-term preservation of electrical energy.
3.
Release (energy output): This process, contrary to compression, primarily involves an expander. During peak electricity demand, high-pressure air from the storage area powers the expansion machine to produce electricity, facilitating energy output. As air expands, it absorbs heat, and the heat generated during compression is transferred back to the expanding air via a specialized heat exchange medium, creating a closed cycle of heat and energy.
2.2 Technical classification and characteristics
There are many classification methods of CAES, which can be divided into supplementary combustion and non-supplementary combustion according to whether a heat source is required during the compression, accumulation, and release processes. Different utilization modes of compression heat can be divided into non-insulated, insulated, and constant temperature types. According to the state of the working medium, it is divided into gaseous and liquid. According to the type of storage facility, it can be divided into salt caverns, hard rock caverns, abandoned mines, depleted oil and gas fields, and aquifers (Zhao et al., 2023). This study mainly introduces the CAES characteristics of different storage facilities (Table 1).
| Types | Principle | Advantages | Disadvantages | References |
|---|---|---|---|---|
| Salt cavern compressed air energy storage (CAES) | Artificial water-soluble underground thick salt layers are used to form a sealed cavern to store high-pressure air. | Salt cavern gas storage has become the first choice of underground high-pressure gas storage systems globally because of its large volume, good sealing, and high gas storage pressure. | Due to the high salt content, it is very corrosive to the compressed air pipelines and units. Moreover, the limited site selection and large deformation caused by the creep of salt rock restricted the rapid promotion and development of salt cavern CAES power stations. | Wan, Zhao, et al. (2024); Wan, Ji, et al. (2024); Wan, Meng, et al. (2023) |
| Hard rock cavern CAES | These chambers feature reinforced concrete linings with composite sealing layers. The pressure from stored high-pressure gas is supported by the surrounding rock, and the concrete lining, combined with the sealing layer, ensures excellent sealing performance. | Compared to natural caverns, lined rock cavern offers superior sealing and can withstand higher storage pressures. | Its development is limited by high costs, geographical conditions, efficiency bottlenecks, and environmental risks. | Hammett and Hoek (1981) |
| Abandoned mine CAES | Abandoned coal mines and mineral resources offer potential for underground energy storage facilities that meet specific storage conditions. Converting these into sealed air storage facilities can repurpose them as CAES systems. | Rich in resources, China faces the closure or abandonment of a large number of coal mines. By 2030, the underground space of coal mines alone will reach 9 billion cubic meters. | Long-term cyclic changes in air pressure can significantly affect the bearing and leakage at the interface between the tunnel's surrounding rock and the sealing structure concrete, thus impacting the gas storage tank's sealing performance. | Fan et al. (2018); Chen and Wang (2022); Bu et al. (2024) |
| CAES for depleted oil and gas fields | Generates electricity by converting excess electrical energy into compressed air and storing it in fully exploited oil and gas fields, releasing the air to generate electricity when needed. | This plan can significantly reduce the cost of site selection, drilling, and other well construction. | It applies only to existing depleted oil and gas reservoirs, limiting its scope. Large-scale, stable operation of CAES in depleted oil and gas fields requires further technical development. | Wan, Sun, et al. (2024) |
| Aquifer CAES | Compressed air is stored in underground porous formations, where it interacts with groundwater to maintain relatively stable pressure by moving the air-groundwater boundary. | Aquifers are common and offer benefits over salt caverns. | They present challenges like managing injection rates, pressure distribution, and air saturation due to their porous nature. | Wan, Jiang, et al. (2024); Yang et al. (2023) |
In summary, China has the potential to build large-scale CAES because of the country's rich mineral resources. However, conventional gas storage potions-such as salt caverns, abandoned mines, depleted oil and gas wells, and pressurized aquifers, all require special geological conditions that severely limit the site selection of gas storage and greatly restrict their practical engineering construction. For areas with construction needs but without these ideal geological conditions, excavating underground chambers in hard rock as underground gas storage is a more realistic method for building CAES power stations. The main technical advantages of artificial hard rock underground chamber gas storage include: geologically widespread suitable strata, relatively straightforward site selection, excellent chamber stability, minimal deformation, wide pressure range, high energy storage capacity, flexible cave section type, strong adaptability in construction, and effective compatibility with wind and solar energy resources. Moreover, it demonstrates favorable economic performance, providing a strong foundation for the development of China's CAES industry and the construction of a new-type power system.
2.3 Current status of AC-CAES construction
In the 1980s, lined rock cavern (LRC) emerged in Sweden, and the first experimental gas storage Grängesberg project began construction in 1998 (Glamheden & Curtis, 2006). It covers three large tank-type gas storage chambers, with a height of 9 m, a diameter of 4.4 m, and a burial depth of 50 m. The chambers are sealed with lined steel plates and have a maximum injection pressure of 52 MPa. Its main function is to construct Grangesberg test chambers to test the sealing system, drainage, and to verify technical feasibility. The Skallen project was initiated in 1999 and successfully transformed into a commercial operation in 2004. The Skallen project adopts a large tank structure with a burial depth of 115 m, a tunnel height of 52 m, and a diameter of 36 m. Reinforced concrete is used as the lining, forming a volume of about 40 000 m3 and a gas storage pressure of 20 MPa. The maximum gas storage pressure during later production and operation is 0.7 MPa (Becattini et al., 2018; Geissbühler et al., 2018; Zhang, Xiang, et al., 2024). The radial deformation of the tunnel is relatively small, meeting the design requirements (Figure 2).
In situ stress measurements were made in the rock mass where the caves are located. The stress field was determined by coring and hydraulically fracturing, involving 200 tests across 60 locations within a 4–13 m depth interval. The test results indicate that: the direction of the principal stresses was uncertain and fluctuated up to 90° between the overcoring and the hydrofracturing.
The pilot project for CAES in Japan was launched in the 1990s (Yokoyama et al., 2002). It was constructed within an abandoned coal mine. The underground gas storage facility is a circular cross-section tunnel with a length of 57 m and a diameter of 6 m, with a total storage capacity of approximately 1600 m3. The chamber is located in a hard rock formation with a burial depth of 450 m. The gap between the sealing layer and the surrounding rock was filled with concrete, and the sealing layer itself was sealed with a synthetic rubber rings. The operated at a pressure between 4 and 8 MPa, with a storge pressure test (Figure 3).
The construction of the CAES project in South Korea began in 2011 (Kim et al., 2012). The gas storage structure is located in a hard rock cave, and the main purpose of the project is to study the application of a hard rock cave with a lining structure in the CAES power station gas storage and the design of the corresponding system. The specific research content includes the form of the cave, the selection of concrete lining and sealing layer materials. The underground gas storage facility is buried at a depth of 100 m and located in a limestone surrounding rock formation. The diameter of the chamber is 5 m, and the entire underground chamber consists of four tunnel-like branches with lengths ranging from 100 to 200 m. There are gas transmission channels connecting the branch tunnels, forming a whole. The sealing layer and surrounding rock are filled with concrete to transfer force, and the sealing layer material was made of a steel plate (Figure 4).
The results of the numerical analyses indicate that the key parameters for ensuring the long-term airtightness of the system are the permeability of the concrete lining and the surrounding rock. A concrete lining with a permeability less than 1 × 10−18 m2 has an acceptable air leakage rate of less than 1% at an operating pressure range of 5–8 MPa at a depth of 100 m. The capillary retention properties and initial gas saturation of the lining are very important parameters, and if the inlet pressure of the concrete lining is higher than the operating pressure, the lining maintains a high-water content, which effectively prevents air leakage (Kim et al., 2012).
In 2016, ALACAES built the world's first test power station for advanced adiabatic CAES technology in the Swiss Alps (Figure 5). The plant utilizes a tunnel-type underground gas storage facility with dimensions of 5 m in diameter, 120 m in length, and a depth of 450 m. Its expected round-trip efficiency is in the order of 70% (Zavattoni et al., 2019). Japan's natural gas storage test project is located in the Kamioka mine; it operated at a test pressure of 20 MPa and is lined with steel. Japan's CAES test project used in the 1990s abandoned coal mine construction, the type of tunnel, size of 57 m long, 6 m in diameter. It was lined with a synthetic (rubber) sealing layer, and the test pressure of 8 MPa. Korea conducted a compressed air storage test project involving an underground cavern with a diameter of 5 m and a length of 10 m. The test pressure was set at 3.5 MPa, and the facility was situated 100 m below ground level. This project aimed to investigate key technical aspects such as the safe storage depth, gas tightness, leakage monitoring, and thermodynamic coupling effects.
Some domestic research and applications have also been carried out. Professor Jiang Zhongming of Changsha University of Science and Technology developed the first hard-rock, shallow-lined underground gas storage chamber (Figure 6). The chamber has a diameter of 4 m, a length of 5 m, a net volume of 28.8 m3, a burial depth of 110 m, a design pressure of 10 MPa, and a test pressure of 8 MPa. The facility undrewent ten complete compressed air charging and discharging cycles, and a series of studies was carried out based on the test results. The test results show that the compressed air temperature field inside the storage chamber exhibits significantly uneven distribution characteristics, and the temperature control system can effectively control the temperature change process in the storage chamber. Under the condition of long-time high-pressure gas storage, the air leakage rate of the test chamber is about 3.2% of the filling rate, and the sealing performance of the test chamber is good. The maximum deformation of the surrounding rock under the internal pressure of 8.7 MPa is only about 0.35 mm, and the deformation influence area caused by the high internal pressure is within 10 m, so the deformation safety of the surrounding rock is good.
On August 21, 2024, the CAES Artificial Cave Laboratory, built by China Energy Digital Technology Group Co. Ltd, was officially completed in Changsha, Hunan Province. As the world's first CAES artificial chamber laboratory, it took 2 years to complete (Figure 7). With the support of top research teams and advanced equipment, research can be conducted on various key technical issues encountered during the construction of artificial chamber-type CAES power stations. The laboratory covers an area of 55 037.25 m2, with a test chamber inner diameter of 6 m, a design pressure of 18 MPa, and a total excavation volume of 9000 m3 in the underground chamber. It can carry out long-term pressure resistance and gas filling and discharging cycle tests of gas storage in real rock environments. The laboratory is equipped with a compressor that can achieve a normal pressure air injection of 10 500 m3/h, accurately simulating the actual operating conditions of CAES. The laboretory enables large-scale in-situ research on the sealing performance of materials and structures, the stability and deformation of surrounding rock in gas storage chambers, the temperature field distribution and thermodynamic characteristics of gas storage chambers, and the pressure, temperature, and aging resistance of materials under high temperature, high pressure, and high humidity multifield coupling environments.
At the same time, some planned projects have also been deployed domestically, such as the 100 MW CAES project in Zhangbei, Zhangjiakou, and the 300 MW CAES project in Longquanshan, Yueyang. China Energy has started construction of a 300 MW CAES demonstration project using artificial chambers in Jiuquan, Gansu, and Chaoyang, Liaoning, leading the world's first 300 MW level CAES artificial chamber technology. A summary of these projects is provided in Table 2.
| Project | Scale (MW) | Project details |
|---|---|---|
| Zhangbei | 100 | The Zhangbei Advanced CAES National Demonstration Project (Hebei, China)—currently the world's largest (100 MW/400 MW·h) and highest-efficiency (70.4% design) advanced compressed air energy storage plant—achieved grid connection on September 30, 2022. It utilizes a hybrid storage configuration (operational above-ground tanks + pioneering engineered hard-rock caverns under construction) with a total capacity of 105 m3, marking China's first application of CAES in geotechnically challenging hard-rock formations at scale and high pressure. |
| Longquanshan | 300 | The Longquanshan CAES Power Station has a designed installed capacity of 300 MW and a single full installed power generation time of 5 h. It has passed the feasibility study report review in December 2022. This project utilizes the hard rock geological conditions of Longquanshan in Yueyang to construct an underground gas storage facility through excavation, providing a new idea for the construction of large-scale energy storage facilities in arid and water-scarce areas and low mountain plains in China. |
| Jiuquan and Chaoyang | 300 | The demonstration projects of 300 MW CAES power stations in Chaoyang, Liaoning, and Jiuquan, Gansu, started simultaneously on December 21, 2022. It is the world's first artificial chamber CA-CAES project with a capacity of 300 MW, and is in a leading position in terms of technical route, solutions, and industrial ecology. The underground artificial chamber is used as the gas storage facility, with a tentative volume of 20.5 m3 and a normal operating pressure range of 12.0–18.0 MPa. It can achieve energy storage effects of charging for 8 h and discharging for 6 h. At present, the design of the artificial chamber gas storage facility in Chaoyang, Liaoning, is still in the research and development stage, while the underground storage facility of the Jiuquan project in Gansu is being excavated. |
In summary, no artificially excavated CAES chamber has yet become operational in China, and this technical field is still in the experimental and research phase, with many key technical problems remaining answered. Different from the underground plant of a hydropower station, the CAES underground storage reservoir not only needs to consider the excavation technology, but also needs to consider several technical difficulties, such as pressure-bearing capacity within 20 MPa, air tightness, fatigue loading and unloading (cycling once a day, running for more than 30 years), and ground stress creep. In addition, in the process of storing and releasing gas in underground gas storage reservoirs, the temperature is affected by the change of gas pressure, and the double change factors of pressure and temperature have an impact on the efficiency and structure of gas storage reservoirs, which affects the overall efficiency of the whole system and the stability of safe operation of gas storage reservoirs.
3 KEY TECHNOLOGIES OF AC-CAES
Compared with other types of gas storage facilities, artificial chamber gas storage facilities have significant advantages. First, they have flexible site selection and can be manually excavated and constructed according to regional energy storage needs, reducing dependence on geology. Second, it can fully utilize underground space, reduce surface area occupation, and effectively save urban land resources. Third, due to its underground location, it can shield against extreme weather and natural disasters, and has strong anti-interference ability, which helps to improve the reliability and stability of CAES. Fourth, underground large capacity spaces have low energy loss during compression, storage, and expansion processes, making them suitable for long-term energy storage. Given the vast market development prospects of AC-CAES systems, this article reviews the technology of artificial chamber gas storage and summarizes the methods and schemes of engineering practice, which are essential for the large-scale construction of AC-CAES systems in the future.
3.1 Site selection
The site selection of the underground gas storage chamber in a CAES power station is a key factor in determining whether the underground structure can meet the requirements for building an underground energy storage chamber (Wan, Ji, et al., 2023; Wan, Yang, et al., 2023), and affects the potential economic, environmental, and social value of the AC-CAES system (Wang et al., 2025). Unlike salt chamber types, artificial chambers are formed by excavating hard rocks, which offers the advantages of rich rock types choose and wide geological distribution. Theoretically, there are no restrictions on site selection. However, due to factors such as national urban development boundaries, ecological protection red lines, and permanent basic farmland protection red lines, such as regional transportation, water temperature, and engineering geology, the site selection of chambers is still one of the important factors causing the slow development of large-scale CAES power stations. By following standardized procedures and improving standards, scientific suitability and economic evaluation of site selection can be achieved, which can further accelerate the large-scale industrialization and promotion of AC-CAES systems.
Gao et al. have researched the CAES system for artificial tunnels both domestically and internationally, focusing on the process of site selection, methods for analyzing influencing factors, and comprehensive evaluation of site selection (Gao et al., 2021). These studies have been briefly validated through some practical cases. Starting from the characteristics of artificial tunnels. Zhou et al. conducted a comprehensive analysis of various factors related to the construction of new tunnels through manual excavation (Zhou et al., 2024). A comprehensive index system based on considering multiple factors, such as ground environment, construction convenience, regional geological characteristics, basic geological characteristics, and hard rock characteristics, was proposed (Figure 8), and a relative weight calculation process was established, along with a method for calculating relative weights.
With the guidance of the national energy strategy, the actual construction of CAES in China has gradually been promoted, and key progress has been made in the site selection of artificial chambers based on practice. Ji et al. established site selection principles for the upcoming artificial cave CAES system, including traffic conditions, rock development characteristics, the surrounding environment of the station site, influence of adjacent strata, regional geological structure, and stability of the cave surrounding rock (Ji, Wang, et al., 2024). Based on this, they proposed a “five-step method” (Table 3) of indoor universal selection, on-site survey, site selection survey, regional geological structure stability assessment, and cave surrounding rock stability assessment, which was applied in the construction process of a 300 MW artificial cave CAES power station carried out by a domestic energy construction enterprise in a certain area of Gansu.
| Projection | Key point |
|---|---|
| Indoor universal choice | Hard rock saturation and compressive strength >60 MPa. The distance between the factory site and the tunnel should be ≤2 km. Seismic intensity ≤ Grade VIII, and establishing 3–4 optional area plans within 5 km of the fault zone |
| Site survey | Terrain and landforms, rock strength, rock properties, fault fractures, seismic intensity, as well as evaluations of roads, water, and electricity |
| Site selection survey | Surveying and mapping geology, geophysical exploration (with survey lines ≥6), drilling exploration (with drilling holes ≥2, depth hole bottom >30 m), and experimental testing (rock quality and physical properties, etc.) |
| Stability assessment of regional geological structures | Based on the indoor general election, on-site survey, and site selection survey, prepare a special report on the regional geological structure stability assessment |
| Stability assessment of the surrounding rock in the tunnel | Comprehensive evaluation of stability calculation and numerical analysis of the overlying rock mass |
3.2 Artificial chamber design
After determining the location of the artificial chamber, the detailed design of the chamber structure, burial depth, sealing system, and other aspects is determined based on the load situation of the chamber. Based on the design premise of determining the pressure range during the operation of the CAES underground chamber and the spatiotemporal distribution law of temperature inside the chamber, stability calculation and analysis of overlying rock mechanics and other loads are carried out to determine the safe burial depth of the chamber. The basic mechanical parameters of the surrounding rock (such as elastic modulus, compressive strength, etc.) are analyzed to determine the shape and size of the chamber. Based on the sealing structure form and the spatiotemporal variation characteristics of material mechanics, the sealing reliability of the lining scheme is determined. Finally, the designed load and structural resistance are repeatedly compared and demonstrated to determine the safety and stability scheme of the structure.
3.2.1 Spatial structure
The spatial structure of AC-CAES storage underground facilities generally includes the spatial layout and cave form structure. Considering the construction cost, the layout often adopts a mode of parallel combination of multiple chambers. The storage chamber adopts a huge cave buried underground, which generally includes one or several chambers with storage depths ranging from 100 to 500 m. The chamber volume generally requires 100 000–220 000 m3 or more, and the common types are tunnel type, large tank type, or factory room type, and its hightest efficiency can exceed 70% under adiabatic conditions (Gasanzade et al., 2023; Song et al., 2020; Zhao et al., 2024) (Figure 9). Tunnel-type LRCs often use multiple circular sections arranged in parallel, with a single tunnel section diameter generally greater than 10 m. The large tank-type gas storage is similar to an LRC gas storage, with a hemispherical dome and bottom, and a cylindrical center. The factory style is between the tunnel style and the large tank style structure, similar to a large underground factory building, with a composite form of arch and flat, straight wall structure. In terms of storage pressure, the AC-CAES system requires a maximum storage pressure of 10–20 MPa, or higher.
Tunnel and large tank types are the two mainstream structures of current energy storage facilities. The large tank LRC structure adopts a cylindrical + hemispherical arch structure, with the arch top and bottom forming a semi-spherical shape, and the middle being cylindrical. The optimal height-to-span ratio is range from 2.0 to 3.0 (Jiang et al., 2024; Zhu et al., 2022). Due to its vertical placement, the large tank-type LRC occupies relatively less underground space, requires less construction work and sealing materials, but has a large height which lead it difficult to control the construction quality. The tunnel type consists of one or more parallel tunnel-shaped cylindrical chambers, and the optimal overall structure is a horizontal cylindrical shape with a recommended cross-sectional diameter of 8–20 m (Xia et al., 2014; Zhang, Wang, et al., 2024). The construction technology of tunnel-type LRC gas storage is relatively mature, and the progress and construction quality are easy to control. However, the parallel arrangement of multiple chambers also results in a large underground space occupation and excessive material consumption during chamber sealing treatment. At the same time, according to the size of the energy storage reservoir and the volume of a single chamber, a combination of one chamber or multiple chambers can be adopted according to design requirements, thereby reducing the construction cost of chambers and improving their self-stabilization capacity.
3.2.2 Depth of chamber
The deeper the chamber, the higher the ground stresses in the chamber, and the lower the loss of stress on the surrounding rock for the same design of reservoir operating pressure system, but the higher the cost, the more difficult it is to achieve a balance between engineering safety and economics. A shallower chamber depth generally offers an optimal balance between safety an economic efficiency, subject to meeting all safety requirements. At the same time, the maximum storage and transportation pressure of the chamber, the specific shape of the structure, and the geological and hydrological conditions should also be taken into account. Due to the lack of experience, a combination of limit analysis, limit equilibrium, and numerical analysis is often used to assess the depth of the chamber, and ultimately determine the reasonable depth of burial. Ji et al. proposed a general method for determining the design of the chamber. First, it is necessary to determine the mechanical parameters of the rock body (modulus of elasticity, compressive strength, and other physical parameters of the rock) through the geological conditions and stratigraphic information of the location of the CAES chamber, and then use analytical or numerical simulation methods to clarify the evolution of the maximum deformation of the peripheral rock of the chamber and the long-term deformation. At the same time, by combining the design load of the lining sealing layer, the reliability index of the safety and stability of the structure is determined. Using this index, the reliability and safety of the shallow buried tunnel structure can be more accurately predicted, and the structural optimization design can be flexibly carried out to meet the design requirements and economic requirements.
However, there is no recognized specification or calculation method for the burial depth of artificial hard rock chamber storage. The design of CAES artificial underground gas storage tanks urgently needs to consider the cohesion and friction of the surrounding rock, and propose a way to determine the potential failure surface angle of the surrounding rock under high pressure, to more accurately determine the necessary burial depth of underground hard rock chamber gas storage tanks.
3.2.3 Lining sealing and stability support
The underground chamber is the core component of the AC-CAES system, whose main function is to store compressed air and use a unique sealing structure to achieve controlled management of the air compression and release process. The existing sealing structures often adopt two types: steel lining reinforced concrete sealing structure and polymer material reinforced concrete sealing structure (Johansson, 2003), which are composed of a sealing layer, lining, surrounding rock, and auxiliary structure (Figure 10). The steel-lined sealing structure has been successfully applied in the construction of high-pressure natural gas underground storage facilities. At the same time, this structure is also used in artificial chambers and reservoirs that have been built or are under construction in China. However, whether it can be used for high-frequency gas filling and discharging in CAES systems, it still requires a lot of research and experimental verification. The sealing structure with polymer materials has flexible and variable properties, which can fully deform in a high circumferential direction when sealing high-pressure gas, timely fill microcracks in reinforced concrete, and transmit gas pressure radially to the lining and surrounding rock, possessing dual characteristics of sealing and load transmission.
Based on the basic operational requirements of the AC-CAES system and the load characteristics of the chamber, the core concept is to use a “flexible sealing structure” made of polymer materials. In this concept, the flexible sealing material of the sealing layer is mainly rubber. Research has shown that butyl rubber, chloroprene rubber, and natural rubber are most suitable in terms of flexibility and sealing performance, enabling effective sealing, load transmission, and resistance to temperature fluctuations during inflation and deflation processes. The sliding layer is used to reduce tangential stress between the sealing and concrete layers, and has the function of reducing frictional resistance. It is typically made of asphalt-based material, which also provides anticorrosion protection for steel and seal the concrete surface in case of gas leakage. The steel mesh and concrete layer achieve the homogenization of stress in the sealing layer, transfer the compressive air pressure load to the surrounding rock, and evenly distribute deformation. The drainage system is an important system for the safe operation of the chamber and has the function of detecting leaks. When the gas storage pressure is low, the groundwater flowing in from the cracks can be drained through the drainage pipe, reducing its pressure on the steel lining and avoiding deformation of the steel lining. The surrounding rock mainly bears the load of the sealed structure, which is the basic condition for the high-pressure air operation of the chamber. Due to the large scale of underground chambers, measures such as concrete replacement, steel arches, anchor rods, anchor cables, or grouting can be taken for areas with poor geological conditions. Combined with sealed structures, an overall support system can be established to ensure the safe and stable operation of the surrounding rocks during operation.
Overall, sealing and stability support are the most difficult and urgent key issues to be solved in the current lining chamber gas storage. The basic theory of design includes the coupling effects of multiple factors such as materials science, structural mechanics, and system heat and force. Existing analysis results and experience are not sufficient to fully demonstrate the feasibility of lining sealing and stability support. It is necessary to further adopt various methods such as theory, indoor testing, and model testing to deeply study their functionality and reliability from multiple aspects. These aspects include materials, structures, understand the deformation response characteristics, leakage characteristics, and influencing factors, further summarize the advantages and disadvantages of various sealing materials and sealing structures, and develop new sealing materials and optimize sealing structures. This will provide systematic solutions for the design, construction, and operation of sealing engineering.
3.2.4 Temperature-pressure coupling and cyclic load stabilization problems
The temperature inside the underground chamber varies with the four continuous processes of inflation-storage-extraction-storage in the CAES system, resulting in a trend of temperature increase-decrease-decrease-increase. Due to the influence of temperature, the pressure also undergoes periodic changes of increase and decrease. In summary, the temperature and pressure distribution characteristics (localized high temperature) inside the chamber are related to parameters such as inflation and deflation rate, inflation and deflation method, chamber type, and distribution engineering scale. The peak gas temperature during the entire operation phase is reached at the end of the first charging (inflation) period. Meanwhile, the internal gas pressure exhibits a stratified distribution due to gravity, while the gas temperature shows a non-uniform distribution as a result of natural convection within the chamber (Hu et al., 2024; Yang & Wang, 2022; Cao et al., 2025). At the same time, the biggest difference between underground gas storage facilities and traditional underground tunnels and pipelines is that their load cycle period is short, and they are accompanied by significant temperature fluctuations due to high inflation and deflation rates. During the use of CAES devices, the underground storage chamber will continuously inflate and deflate: running continuously every day for 365 days a year, assuming a service life of 50 years, and the total number of cycles can be close to 20 000. From a thermodynamic perspective, an increase of 1 MPa in chamber pressure may lead to a temperature rise of 13°C.
In practice, the maximum temperature difference within an underground chamber can be 70–80°C per compressed air storage unit cycle, implying high structural temperature stresses and possible opening and closing problems between the various layers of the structure. When designing the dimensions of a single chamber, in addition to the size of the gas storage, it is also necessary to consider the appropriate ratio between the length of the tunnel and the diameter of the chamber. The larger the ratio between chamber length and diameter, the higher the extreme temperature values inside the reservoir and the more complex the temperature control measures. Since the main variable loads on the surrounding rock come from high-frequency, cyclical temperature, and pressure loads, this requires that the compressed air storage underground gas storage chamber meet the performance requirements of sealing, surrounding rock stability, and deformation coordination. The chamber volume, geometry, operating pressure, depth of burial, water table, permeability, and strength of surrounding rock all affect the above performance requirements. How these problems can be solved also deserves an in-depth study.
The thermodynamics and geomechanics of lined rock caverns were analyzed by the TOUGH-FLAC method by Rutqvist et al. The results show that 96.7% of the energy injected during compression can be recovered in the subsequent decompression process, while 3.3% of the energy is lost due to heat transfer to the surrounding medium. Geomechanical analysis showed that tensile effective stresses of up to 8 MPa could be generated in the liner as a result of the air pressure exerted on the inner surface of the liner, while thermal stresses were relatively small and compressive. By selecting an internal synthetic seal, the maximum effective tensile stress was reduced from 8 to 5 MPa, but it was still in considerable tension (Rutqvist et al., 2012).
3.2.5 System integration and control direction
1.
System integration: The CAES system can be divided into an energy storage subsystem and a power generation subsystem, mainly including key components, such as a generator, compressor, combustion chamber (non-supplementary combustion CAES does not include this part), gas storage chamber, expander, and electric motor. Efficient component selection, research and development, and compatibility among device and systems during the operation and the system configuration subsystem for the two processes should be conducted to optimize the working efficiency of key components in both the energy storage and power generation system, thereby improving overall operating efficiency of the system.
2.
Pressure control: The impact of pressure on CAES systems is significant and multifaceted. In the compression stage, higher the pressure results in higher air density at the same temperature, enabling a storage tank of the same volume to store more air and achieve a higher energy storage density. In the expansion stage, higher initial inlet pressure and lower outlet pressure lead to greater work output. It is essential to optimize and control parameters such as air velocity, volume, and moisture content during the compression and expansion process to achieve efficient air processing and reduce energy loss.
3.
Cycle process control: The artificial chamber adiabatic CAES system can store the heat generated during the compression process and use this heat to preheat the compressed air during the power generation process to improve system efficiency. During the compression stage, stable control of compressed air pressure can be achieved by precisely controlling the operating parameters of the compressor, such as speed, power, and so on. In the expansion stage, by adjusting the opening of the inlet valve of the expansion machine or adjusting its speed, the pressure change of the air during the expansion process can be controlled to ensure the stable operation of the system.
4.
Configuration plan: key components such as compressors and expanders require special attention to ensure the operational efficiency of the entire power plant. The compressor should have an efficient cooling and lubrication system, while taking into account measures such as noise and vibration isolation to ensure its long-term stable operation. The selection of the expansion machine should be matched with the compressor, and an efficient heat exchange system and speed control system should be configured to improve its power generation efficiency and stability. At the same time, the sealing and wear resistance of the expansion machine need to be considered to ensure that it can efficiently utilize the energy of compressed air for power generation.
On the whole, by reasonably configuring the parameters and types of key components, such as the compressor, expander, and storage chamber, the overall performance of the system can be optimized, and the efficiency of energy storage and power generation can be improved. Through high-efficiency heat recovery technology and equipment, the heat generated in the compression process can be recovered and utilized, reducing energy loss and improving system efficiency. By improving system design and optimizing operating parameters, friction loss and leakage loss of the system can be reduced, thus improving the overall efficiency of the system. By adopting advanced intelligent control technology and algorithms, real-time monitoring and optimized control of the system operating status can be realized, thereby improving the stability and efficiency of the system. However, the configuration and optimization of the CAES system, especially the rational management of temperature and pressure during operation, remain a focus current research and require further optimization through practical testing.
3.3 Excavation and evaluation of chambers
3.3.1 Chamber excavation
The underground chamber is a key component of the AC-CAES system. Based on the construction experience of underground chambers such as mine tunnels and tunnels, there are mainly two excavation methods suitable for hard rock tunnels in artificial chambers. One is drilling and blasting method. Another is tunneling machine method (Feng et al., 2021; Zhou & Zhai, 2018; Ji et al., 2023; Xu et al., 2022; Onifade et al., 2023). The tunneling machine method is further divided into the tunnel boring machine (TBM) method and shield tunneling machine method, and the TBM method is generally used for the excavation of hard rock formations. The drilling and blasting method is a series of processes, such as drilling, charging, and blasting, which use the energy generated by explosive charges to break rocks and achieve tunnel excavation. During the blasting process, explosives explode in the blast hole, producing powerful shock waves and high-pressure gas, causing the rock to be crushed by various forces, such as compression, shear, and tension. The TBM method is a mechanical rock-breaking method developed from shield tunneling technology, which uses tunneling machines to excavate tunnels and achieve systematic operations of rock fragmentation, slag removal, and support. TBM method is more suitable in hard rock formations. The cost comparisons of the above two types of methods are shown in Table 4.
| Comparison project | Drilling and blasting method | TBM |
|---|---|---|
| Average tunneling speed | 10–30 m/day | 15–60 m/day |
| Initial investment | Less (equipment and site) | Higher (equipment cost dominates) |
| Labor demand | Higher demand | Less demand |
| Geological risk cost | Construction flexibility and lower risk | Equipment jamming and maintenance costs are high |
Since the construction of pumped storage power stations in China began in the 1960s, after more than 60 years of development, the most common excavation method for underground hard rocks is the drilling and blasting method (Ma et al., 2020). At the same time, the construction of AC-CAES systems currently under construction also adopts the drilling and blasting method. The technology of blasting excavation for CAES artificial chambers has been developed in China. Based on the demand for reducing blasting stress, technological explorations have been gradually made in three aspects, including the design of the cut area position, the design of the maximum charge amount, and the layout design of the blasting face. First, in response to the design requirements of the cut area during chamber blasting construction, a calculation method has established for parameters, such as the length, width, top apex value, distance from the horizontal centerline of the chamber, and distance from the bottom of the cut area, resulting in a design method for the position of the cut area. Next, the maximum charge amount for each section is determined, and by converting and decomposing the total charge amount for a single blasting of the tunnel into several combinations of small charges, attempts are made to increase the number of segments as much as possible within the total delay time range. The charge amount for each segment is calculated and design separately to achieve segmented detonation while meeting the requirements for disturbance to the surrounding rock of the tunnel wall. Furthermore, optimization design was carried out for the layout of the blasting face, resulting in a “1–2” change from one face to two faces in the pilot tunnel, and a “2–4” change from two misaligned faces in the pilot tunnel section to four blasting faces. Additionally, a “2–4” design method of simultaneous blasting of the upper and lower faces according to the “misalignment and same number” was applied until the bottom of the tunnel. Ultimately, the technology of drilling and blasting excavation for the excavation of a superlarge section artificial chamber was developed, which was successfully applied to the excavation of a 300 MW CAES artificial chamber in Gansu Province, China.
TBM technology has outstanding advantages over drilling and blasting methods in terms of safety, rock disturbance, construction quality, and automation and intelligence. It has been applied in underground tunnel construction in hydropower engineering, transportation, municipal engineering, and other fields. With the continuous advancement of TBM technology, research and demonstration of TBM application in underground tunnel construction have been carried out in China. First, in the analysis of engineering geology, TBM is suitable for a wide range of rock types, especially in hard rock environments of underground tunnels. Second, unlike the construction of underground chambers in pumped storage power stations, which has a relatively long length, a certain turning radius, and possible inclined shafts, artificial chambers for compressed air underground energy storage are generally tunnel-shaped, horizontally arranged, and have a relatively short chamber length, making the engineering difficulty relatively easy to achieve. At the same time, China has made certain progress in the areas of non-pilot tunnel starting technology, expandable TBM technology combined with support technology and so on (Sigl et al., 2020). In the future, it is necessary to further leverage the leading role of the artificial tunnel TBM construction method engineering design unit, standardize the excavation section, and achieve cost-effectiveness. At the same time, a joint research and development approach shouled be adopted between investors and equipment manufacturers to promote the design, manufacturing, application, and mechanization level of TBM equipment based on the characteristics of artificial tunnel construction.
3.3.2 Chamber evaluation
1.
In-depth evaluation of geological lithology, geological structure, hydrology, physical geology, and seismic activity will be carried out, using evaluation methods such as geological surveying, geophysical exploration and drilling, testing and experimentation, and numerical simulation to obtain the geological condition evaluation results of the selected area. Using geological and engineering geological theories, conduct geological mapping of the selected area, analyze the characteristics of the underground environment, and pay special attention to environmental impacts such as groundwater pollution, drainage convenience, and earthquake resistance. By using geophysical methods such as controlled source magnetotelluric sounding and seismic methods, key points are selected for drilling and exploration to obtain core data of underground rock layers, and to identify the properties, structure, and stability of the rock layers. Evaluate the mechanical properties and stability of rock formations through rock integrity tests, rock physical property tests, rock mechanical property tests, and so on. At the same time, numerical simulation methods such as finite element analysis and discrete element analysis are used to simulate and analyze the geological conditions of the selected area, as well as to evaluate the safety and stability of the tunnel construction.
2.
This involves determining the stability and safety of the tunnel structure under high-pressure air, geological stress, and other external loads. The evaluation content includes geological survey results, structural analysis, stability, safety margin, and so on. The evaluation methods include numerical simulation, physical simulation, and on-site testing. Using numerical simulation methods such as finite element analysis and discrete element analysis, the load-bearing structure of the tunnel is simulated and analyzed. Through simulation analysis, data such as stress distribution and deformation of the surrounding rock of the tunnel can be obtained, providing a basis for evaluating the load-bearing structure. Physical simulation methods, such as similar material simulation and centrifuge simulation, can be used to conduct simulation tests on the load-bearing structure of the tunnel. Through physical simulation tests, the deformation, failure, and other phenomena of the load-bearing structure of the tunnel can be intuitively observed, providing an intuitive basis for the evaluation of the load-bearing structure. Real-time monitoring of the load-bearing structure of the tunnel is carried out using on-site testing methods such as stress monitoring and deformation monitoring. Simultaneously conducting on-site testing to obtain stress, deformation, and other data of the tunnel load-bearing structure under actual load, providing a real-time basis for the evaluation of the load-bearing structure.
3.
A reasonable air-tightness assessment is conducted to determine the sealing effect of the tunnel structure under high compressed air pressure and other external factors, ensuring the operational efficiency and safety of the tunnel. Sealing evaluation includes material evaluation and sealing performance testing, mainly using experimental testing and numerical simulation analysis methods. The experimental testing adopts professional testing equipment to conduct permeability testing and sealing testing, obtaining the porosity and permeability of the sealing material. To accurately determine the sealing performance, the microstructure of the sealing material is obtained under set conditions to determine whether there are aging, corrosion, or other phenomena. Sealing performance testing can be conducted using experimental and numerical simulation methods. During the test, a tunnel model is established, and a certain pressure difference is applied to the tunnel. During the testing process, key data such as pressure changes and leakage rates should be recorded to quantitatively evaluate the sealing performance. Numerical simulation can use seepage simulation software to establish simulation models under different working conditions and study the sealing effect of artificial chambers in variable parameter environments.
4.
The CAES system for artificial tunnels ultimately aims to achieve planned operational efficiency and benefits, with particular attention paid to establishing evaluation methods for heat transfer performance. By using evaluation methods and technologies, such as real-time monitoring and data analysis, simulation and performance prediction, expert evaluation, and on-site inspection, the evaluation results of the system can be obtained. Establish a real-time monitoring system for the CAES system to manage operational data, such as pressure, temperature, flow rate, power, etc. Using simulation technology, predict the performance of the system, such as efficiency, stability, safety, and so on. Further evaluate the heat transfer efficiency, power generation efficiency, and even economic benefits of the entire system based on expert opinions. Finally, based on the evaluation results, develop targeted operation and maintenance strategies to reduce the operating and maintenance costs of the system.
4 CHALLENGES
1.
Site selection and geological conditions. The site selection of the AC-CAES system needs to meet specific geological conditions, such as rock hardness, stability, permeability, and so on. In reality, the geological areas that meet these conditions are still relatively limited, especially in some new energy areas, such as deserts, and other remote areas, which often do not have the conditions or high construction costs for CAES power station ground construction. The use of mature methods or the development of reasonable operating norms or standards to screen out the range of plant sites that meet the requirements for database construction, and how to evaluate the feasibility and economy of the proposed site for database construction, has become an important issue in the construction of AC-CAES power stations.
2.
Burial depth and sealing performance. The sealing performance of the tunnel is the key to the efficient operation of the CAES system, and the burial depth of the tunnel determines the load conditions of the tunnel. Achieving a balance between economic requirements and engineering safety is the primary issue to be solved for the burial depth and sealing of the tunnel. In addition, from a sealing perspective, existing sealing materials and technologies are unable to fully meet the long-term demand for high-pressure air, and there is a need to develop new and efficient sealing materials and technologies. At the same time, the design and construction of the sealing layer also need to consider multiple factors, such as the structural characteristics, geological conditions, and operating pressure of the chamber. Unreasonable design and construction may lead to gas leakage, affecting the efficiency and safety of the system.
3.
Process and equipment. The construction of artificial chambers requires advanced construction techniques and equipment to ensure that the shape, size, and stability of the chambers meet the design requirements. However, under complex geological conditions, the construction process may be limited by factors such as stone hardness, fault distribution, and groundwater content, resulting in significant uncertainty during the construction process. In addition, the core equipment of the CAES system includes compressors, turbine expanders, heat exchange equipment, and so on. The performance and quality of this equipment directly affect the efficiency and reliability of the system. Considering the incomplete serialization of equipment in the current market, some of which require customized production, and research and development costs are also key factors restricting technological development.
4.
Thermodynamic and cyclic load management. High-frequency pressure cycles (up to 20 000 cycles over 50 years) require sophisticatedthermal management. Numerical models simulate temperature-pressure coupling effects, while heat recovery systems (e.g., ALACAES' adiabatic design) improve efficiency by reusing compression heat during expansion. China's CAES laboratory in Changsha conducts large-scale in situ tests to optimize temperature distribution and material durability under multifield coupling conditions.
5.
Laboratory construction and experimental methods. The associated laboratory relies on an artificially created cavern energy storage facility. The results of the theoretical analysis require experimental verification, especially concerning the critical structural parameters of the designed cavern and its long-term operational stability, which need to be determined through experimentation. In particular, aspects such as the structural type of the real cavern system, characteristics of sealing materials, pressure-bearing capacity, thermodynamic properties, key equipment, and auxiliary systems can only be evaluated through experimentation. Therefore, technologies related to the development and performance testing of sealing materials for artificial chambers, research into the structural types of artificial chambers, establishment and validation of design theories for artificial chambers, verification of associated auxiliary systems for artificial chambers, development of construction techniques and equipment for artificial chambers, and validation of the thermodynamic properties of gas storage in artificial chambers, all need further validation through experimental means.
6.
Standardization and normalization. At present, the standardization work in the CAES field is still in its infancy, and there are many problems in the construction of the standard system, such as insufficient top-level design, weak systematization of standard preparation and approval project, and a lack of key technical standards. The lack of unified norms and regulatory standards may introduce inconsistencies and risks in the construction and operation of artificial tunnels. It is necessary to develop and improve relevant norms and regulatory standards to ensure the safety and reliability of the system.
5 CONCLUSION AND PROSPECT
1.
Site selection should take into account local rock types, geological distribution, and ecological constraints, balancing various factors and establishing an evaluation index system to guide the process. Combining theoretical site selection work with practical tunnel construction needs can enhance tunnel construction efforts.
2.
Detailed analysis should be conducted during the design phase for artificial chamber construction. Reliable methods should be used for spatial layout, burial depth, lining sealing, and stability support of underground chambers. Considering the entire CAES system as a whole is essential for ensuring operational efficiency and stability of energy storage reservoirs.
3.
The blasting method is the most established technique for excavating underground artificial chambers. Developing a technical system focused on stress relief for determining the excavation hole location, setting the maximum charge quantity, and organizing the blasting face offers significant reference and practical value for constructing artificial chambers. Additionally, further research into the conventional TBM tunneling method is crucial for advancing the automation and safety of underground construction.
4.
A thorough assessment of the chambers' location, structural integrity, sealing efficiency, and operational conditions is essential. This includes developing evaluation techniques and methods to ensure the CAES system's stable operation. Based on these evaluations and expert conclusions, appropriate operation and maintenance strategies should be created to reduce operating costs and to reduce operating costs and maximize the economic and social benefits of the CAES system for artificial chambers.
1.
Enhance site selection technology and sealing performance of artificial chambers. Site selection should prioritize underutilized light and wind resources in remote locations like deserts and high mountains, considering geological issues such as faults and fissures. Develop new sealing materials and conduct adaptability tests based on chamber characteristics.
2.
Strive to make a technological breakthrough. Material fatigue, creep, and geomechanical instability in CAES systems require a multidisciplinary approach combining advanced modeling (FEA/DEM), material innovation, and real-time monitoring. Addressing these challenges is critical for scaling CAES in diverse geological settings and achieving cost-effective, long-duration energy storage.
3.
Reduce construction costs by optimizing equipment and processes. Address high expenses related to equipment procurement, land acquisition, environmental regulations, and transportation in remote areas. Incorporate economic and sustainability considerations into the construction phases.
4.
Establish specifications and standards for artificial chamber construction in China, which is currently in its early stages. Improve top-level design, standardize key technologies, and create unified market regulations to mitigate uncertainties. Strengthen laboratory development to validate technology through testing, using feedback to formulate and enhance relevant norms and standards, ensuring the CAES system's safety and reliability.
AUTHOR CONTRIBUTIONS
Jifang Wan: Conceptualization; data curation; formal analysis; writing; methodology; software. Mingyin Li: Writing; conceptualization; methodology. Rui Zhao: Supervision; review; project administration. Wendong Ji: Writing; visualization. Jingcui Li: Validation; formal analysis. Maria J. Jurado: Validation; investigation. Yangqing Sun: Methodology.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the financial support provided by the National Natural Science Foundation of China under Grant (52474080) and the National Key R&D Program of China (2024YFB4007100).
CONFLICT OF INTEREST STATEMENT
The authors declare no conflict of interest.
Biography
Mingyin Li, Engineer, is currently with China Energy Deep Underground Technology (Hubei) Co., Ltd. He received his BEng in Mechanical Engineering from Zhengzhou University in 2015 and his MSc in Mechanical Design and Theory from the PetroChina Research Institute of Petroleum Exploration & Development (RIPED) in 2018. During his MSc studies (2015–2018), he conducted research at the CNPC Engineering Technology R&D Institute, contributing to rotary steerable systems (RSS), geosteering, and vertical seismic profiling (VSP) technologies. His professional experience includes: Engineer, CNPC Engineering Technology R&D Institute (July 2018 onward); Deployment to PetroChina Tarim Oilfield Company (November 2018 to January 2023), focusing on deep/ultra-deep well drilling/completion design and process research; R&D Engineer, CNPC Kunlun Manufacturing Co. Ltd. Innovation Center (February 2023 to December 2024), focusing on high-performance downhole drilling motors research; Current Role focus on compressed air energy storage (CAES) and monitoring systems. He has published 10 papers, filed 12 oilfield technology patents, and received multiple CNPC Outstanding Individual awards. His primary research now focuses on drilling and completion technology, salt cavern gas storage, and monitoring systems.
