The lined rock cavern (LRC) compressed air energy storage (CAES) system is currently regarded as one of the most promising methods for large-scale energy storage. However, the safety of LRC under high internal pressure has emerged as a critical issue that restricts their development. While scholars have focused on the safety of LRC under multiphysics field coupling, few have noticed the inevitable damage sustained by the primary load-bearing components—the surrounding rock and concrete lining—under high internal pressure, compromising their strength and permeation resistance. This study investigates the impact of damage to the surrounding rock and lining concrete on the stability and airtightness of the CAES cavern. First, a damage-permeability evolution model was established by analyzing cyclic loading and unloading test data on concrete samples. Then, a thermo-hydro-mechanical damage (THM-D) coupling model for the CAES cavern was developed and validated against operational data from the Huntorf plant. The coupling responses of both the surrounding rock and lining were compared and analyzed under three different schemes of the first charging and discharging operation. The results revealed the correlation between the air temperature in the cavern and the injection rate and the uneven damage evolution of the surrounding rock and lining caused by the geostress distribution coupled with the heat transfer process. Through the analysis, a higher air injection rate causes more lining damage and air leakage, posing greater risks to engineering safety and airtightness. However, the reduction of inflation time will weaken this effect to some extent. These findings offer valuable insights into the design, construction, and safe operation of LRC compressed air energy storage systems.
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.
Currently, there is a lack of research on the impact of excavation damage on the stability of underground compressed air energy storage (CAES) chambers. This study presents a comprehensive analytical framework for evaluating the elastic and elastoplastic stress fields in CAES chambers surrounding rock, incorporating excavation-induced centripetal reduction of rock stiffness and strength. A proposed model introduces exponential reduction functions for the deformation modulus and cohesion within the excavation disturbed zone (EDZ), deriving analytical solutions for both elastic and elastoplastic stress distributions. A case study of a practical engineering project validates the theoretical formulations through comparative analysis with numerical simulations, demonstrating strong consistency in stress field predictions. The main findings indicate that the EDZ causes a significant non-monotonic variation in the elastic hoop stress distribution. While it does not significantly affect the range of the plastic zone, it reduces the permeability and bearing capacity of the surrounding rock, highlighting the necessity of integrating the centripetal reduction of mechanical properties and strictly controlling excavation-induced damage in the design practice. Furthermore, this study provides a new approach for the selection of lining materials and structural design for CAES chambers: the radial stiffness smoothly increases to match the EDZ surrounding rock stiffness, and the cohesion exceeds that of the surrounding rock, which can significantly optimize the overall system's stress distribution. This study provides valuable insights and references for the selection of excavation methods, stability assessment, and support structure design for CAES engineering, and holds significant importance for improving the CAES technology system.
A significant number of salt caverns have high proportions of insoluble sediments, but the thermal storage utilization potential of insoluble sediments remains understudied within current research. Therefore, this study aims to explore the feasibility of an integrated compressed-air energy storage (CAES) coupled with insoluble sediment as the thermal storage media for salt caverns. In order to fulfill this objective, this study presents two steps to analyze the insoluble sediment's thermo-mechanical behavior under ordinary CAES conditions and coupled thermal energy storage (TES) conditions separately. A multiphysics-coupled numerical model was developed to investigate the thermal behavior of insoluble sediments at different heights. Then, a dual-cavity model with a sediment-filled channel was constructed to study the heat storage process in long- and short-term modes. Results demonstrated that sediment effectively protected cavern walls from thermal shocks caused by compressed air, maintaining temperature differentials within 1 K. Dual-cavity simulations revealed the sediment's capability to mitigate the temperature fluctuation of compressed air in caverns, achieving a 66% temperature reduction in the outflow interface during operation. The findings confirmed the feasibility of utilizing insoluble sediments for long-term thermal storage applications involving thermal cycles with ΔT = 150 K, attaining a heat storage density of 50 kW·h/m³. The results show that the heat capacity of the sediment contributes to the cavern wall's stability and provide references for developing integrated CAES-TES systems in sediment-filled salt caverns.
Carbon capture, utilization, and storage (CCUS) is widely recognized as a technological system capable of achieving large-scale carbon dioxide emission reductions. However, its high costs and potential risks have limited its large-scale implementation. This study focuses on enhancing the economic viability of traditional CCUS by proposing a novel technological concept and system that integrates CCUS with water extraction, geothermal energy harvesting, hydrogen production, and energy storage. The system comprises three interconnected modules: (1) upstream CO2-enhanced water recovery (CO2-EWR), (2) midstream green hydrogen synthesis, and (3) downstream energy utilization. Through detailed explanations of the fundamental concept and related technological systems, its feasibility is demonstrated. Preliminary estimates indicate that under current conditions, the system lacks economic advantages. However, significant reductions in hydrogen production costs could enable the system to yield a profit of nearly 1000 Chinese Yuan (approximately 145 US dollars) per ton of CO2 in the future. Following an in-depth investigation, priority implementation in China's Tarim Basin and Ordos Basin is recommended. This technological system could significantly extend the industrial chain of traditional CCUS projects, promising additional social and ecnomic benefits. Furthermore, the involved gas–water displacement technology can help manage formation pressure and reduce leakage risks in large-scale carbon storage projects.
Deep Underground Science and Engineering (DUSE) is pleased to release this issue with feature articles reporting the advancement in several research topics related to deep underground. This issue contains one perspective article, two review articles, six research articles, and one case study article. These articles focus on underground energy storage, multiscale modeling for correlation between micro-scale damage and macro-scale structural degradation, mineralization and formation of gold mine, interface and fracture seepage, experimental study on tunnel–sand–pile interaction, and high water-content materials for deep underground space backfilling, analytical solutions for the crack evolution direction in brittle rocks, and a case study on the squeezing-induced failure in a water drainage tunnel and the rehabilitation measures.
The perspective article deals with the construction of the first underground energy storage complex in Xuzhou, China. This article entitled “Compressed air and hydrogen storage experimental facilities for sustainable energy storage technologies at Yunlong Lake Laboratory (CAPABLE)” (DOI: 10.1002/dug2.70043) reported the construction progress and technical development of lined rock caverns (LRC) facility for compressed air and hydrogen storage. This facility will focus on the verification of load transfer, damage and failure mechanism of the LRC structure, and the development of new materials for both lining and sealing layers. Three key problems for compressed air and hydrogen storage in underground spaces will be addressed: cavern stability, sealing efficiency, and minimum environmental impacts.
One review article focuses on the genesis and preservation mechanisms of 10 000-m ultradeep dolomite reservoirs in China (entitled “Genesis and reservoir preservation mechanism of 10 000-m ultradeep dolomite in Chinese craton basin”, DOI: 10.1002/dug2.12112). This is indeed the first article on ultradeep reservoirs published in the Journal of DUSE. Ultradeep dolomite reservoirs are particularly important for the future oil and gas explorations in China's marine craton basin. This review article systematically expounds the genetic mechanism and reservoir formation mechanism of ancient dolomite, clarified the limiting factors of dolomitization process and the preservation mechanism of dolomite reservoirs in deep buried environment, explored the spatial distribution of dolomite reservoirs, and identified the major zones of oil and gas exploration in 10 000-m deep layers. This article has no doubt provided the latest update on the fundamental knowledge for future oil and gas explorations in China.
The other review article reports on the multiscale simulations for mechanical problems of rocks (entitled “A review of multiscale numerical modeling of rock mechanics and rock engineering”, DOI: 10.1002/dug2.12127). This article systemically reviews both geometrical and mechanical multi
Geothermal exploration and development in North Africa have advanced significantly, driven by the region's rich geothermal resources and rising energy demand. The countries of Mauritania, Morocco, Algeria, Tunisia, Libya, and Egypt are located near tectonic plate boundaries (African and Eurasian plates), giving them substantial geothermal potential. Various exploration activities, including geological surveys and geophysical studies, have been conducted to assess geothermal reservoirs and identify suitable development sites. This article reviews the progress made in geothermal exploration across the region, highlighting the key activities undertaken to evaluate geothermal resources. It also explores how government policies have played a critical role either in fostering or in freezing geothermal development. The different conducted assessments such as analyzing geological structures, hydrothermal systems, and subsurface temperatures lead to identify suitable sites for geothermal development and improve the understanding of subsurface conditions and ongoing projects. Today, some countries in North Africa are positioning themselves to become important players in the global geothermal energy landscape, and with continued investment and concerted efforts, the region has the potential to emerge as a prominent player in the global geothermal energy landscape.
Compressed air energy storage (CAES) caverns transformed from horseshoe-shaped roadways in abandoned coal mines still face unclear mechanisms of force transfer, especially in the presence of initial damage in the surrounding rock. The shape and size of the initial damage area as well as their effect on cavern stability remain unclear. Due to the complex geometry and multiphysical couplings, traditional numerical algorithms encounter problems of nonconvergence and low accuracy. These challenges can be addressed through numerical simulations with robust convergence and high accuracy. In this study, the damage area shapes of a CAES cavern are first computed using the concept of damage levels. Then, an iteration algorithm is improved using the generalization α method through the error control and one-way coupling loop for fully coupling equations. Finally, the stability of the CAES cavern with different damage zone shapes is numerically simulated in the thermodynamic process. It is found that this improved algorithm can greatly enhance numerical convergence and accuracy. The nonuniformity of the elastic modulus has a significant impact on the mechanical responses of the CAES cavern. The cavern shape with different damage zones has significant impacts on cavern stability. The initial damage area can delay the responses of temperature and stress. It induces variations of temperature in the range of approximately 1.2 m and variations of stress in the range of 1.5 m from the damage area.
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