Search Results (139)

Large-scale adiabatic compressed air energy storage (A-CAES) is essential for stabilizing power grids with high renewable energy penetration. However, the complex thermo-mechanical coupling in its multistage expansion and reheat systems poses significant challenges for dynamic control and operational safety. This study develops a coordinated control framework for the A-CAES energy release process. Based on control-oriented characteristic analysis revealing bidirectional power–temperature coupling mechanisms, a power setpoint feedforward decoupling strategy is proposed, reducing the stage-averaged temperature dynamic deviation of the four expander inlet temperatures from 7.74 K to 1.57 K during the upward power ramp. Furthermore, the gradient-based optimization (GBO) algorithm with the piecewise reset ITAE objective function is employed to optimize the PI controller parameters, yielding stage-averaged temperature dynamic deviations of 1.882 K and 2.249 K during AGC ramp-up and ramp-down, respectively, corresponding to reductions of 27% and 26% relative to empirical tuning. Numerical simulations of load rejection and three-phase short-circuit faults indicate the system’s dynamic stability and safety margins under the considered extreme conditions. This work provides model-based technical support for a 300 MW-class A-CAES demonstration project. Full article

The increasing penetration of renewable energy has created an urgent need for economically competitive large-scale energy storage technologies. Conventional economic evaluations mainly focus on lifecycle costs while neglecting market participation, revenue diversification, and investment uncertainty. This study proposes an integrated lifecycle economic assessment framework combining discounted cash flow (DCF) theory, lifecycle cost analysis, multi-market revenue modeling, and uncertainty analysis. A revenue-adjusted indicator, termed Net Levelized Cost of Storage (Net LCOS), is introduced to quantify the actual economic competitiveness of energy storage technologies by incorporating revenues from energy arbitrage, ancillary services, and capacity remuneration. The proposed framework is applied to three representative large-scale energy storage technologies: pumped hydro storage (PHS), compressed air energy storage (CAES), and battery energy storage (BES). The results show that PHS exhibits the lowest levelized cost of energy (LCOE) (0.519 RMB/kWh) and the strongest economic robustness owing to its long service life and superior capital amortization capability. Incorporating multi-market revenues substantially improves the economic performance of all storage technologies. BES exhibits the largest reduction in Net LCOS, whereas PHS maintains the lowest Net LCOS and the strongest overall economic competitiveness. Sensitivity analysis identifies conversion efficiency, capital investment, capacity remuneration, and operational utilization as the dominant determinants of storage economics. The proposed framework extends a comprehensive approach for comparing large-scale energy storage technologies by integrating lifecycle costs, market revenues, and uncertainties, supporting investment decisions and electricity market design. Full article

This study presents an integrated multidisciplinary framework for evaluating the reuse of abandoned underground mining infrastructure in Bosnia and Herzegovina as sustainable underground energy storage systems that support the energy transition and decarbonization. The research focuses on the Central Bosnia and Tuzla coal basins, using case studies from the Zenica and Tuzla mining regions to assess Underground Pumped Hydroelectric Energy Storage (UPHES), Compressed Air Energy Storage (CAES), and gravity-based energy storage technologies. The methodology integrates geological and geotechnical characterization, thermo-hydro-mechanical (THM) analysis, thermodynamic calculations, and Multi-Criteria Decision Analysis (MCDA) to evaluate technical, operational, and safety performance. Methane mitigation, smart ventilation, thermal stability, and geomechanical behavior under cyclic loading were also considered. The results indicate that sedimentary coal basins are well suited for UPHES and gravity-based storage systems, with UPHES capacities reaching 1.75 GWh per cycle under optimized conditions, while the separately evaluated solid-mass gravity storage system provides a capacity of 6.15 MWh. Evaporite formations in the Tuzla Basin offer favorable conditions for CAES because of the low permeability and plasticity of halite, enabling storage capacities exceeding several GWh. THM analysis confirmed acceptable geomechanical stability during cyclic operation, while the economic assessment based on the Levelized Cost of Storage (LCOS) demonstrated the long-term competitiveness of Abandoned Mine Energy Storage (AMES) compared with battery technologies. Overall, the findings highlight abandoned mines as strategic low-carbon assets for renewable energy integration and regional post-mining transition. Full article

In salt cavern compressed air energy storage (CAES) systems, slag particles entrained by high-pressure airflow can cause pipeline wear and flow instability, posing challenges to long-term operational safety. However, direct experimental studies are constrained by high-pressure, large-scale conditions and transient multiphase flow complexities. This study uses Fluent, a numerical simulation method based on gas–solid two-phase flow theory, to investigate the flow characteristics, particle dynamics, and erosion behavior in the above-ground pipeline of CAES system. Results reveal uneven gas velocity distribution, with the lowest flow (≤2.3 (m/s)) in the main pipeline favoring particle deposition, and complex vortex structures at branch connections. Particles accumulate on the outer wall of 90° elbows due to centrifugal effects, leading to localized erosion, with severe wear occurring at impact angles of 20–30°. Over a 30-year operational cycle, the predicted maximum wear depth is 0.38 mm, which remains below the existing protective cladding thickness of 0.5 mm. The findings not only provide a theoretical basis and design insights for optimizing wear protection strategies, but also hold positive implications for enhancing the economic sustainability and environmental benefits of large-scale energy storage systems. Full article

High penetrations of renewable generation are increasing the need for long-duration energy storage capable of intertemporal balancing and reserve provision. However, the market value of heterogeneous storage portfolios under shared grid-connection constraints remains insufficiently quantified. This study develops a risk-averse day-ahead co-bidding model for a hybrid pumped-hydro and compressed-air energy storage (CAES) portfolio participating jointly in energy and spinning-reserve markets. Monte Carlo sampling and scenario reduction are used to represent price uncertainty, while conditional value-at-risk (CVaR) captures downside-profit risk. Shared point-of-common-coupling (PCC) constraints explicitly couple electricity sales, purchases, and reserve offers. Compared with homogeneous pumped-hydro expansion, replacing the equivalent incremental pumped-hydro capacity with CAES increases the cumulative reserve bid by 65.71%, while expected profit decreases by 1.17% and raw-scenario back-test CVaR remains nearly unchanged, decreasing by only 0.05%. Relative to the unconstrained hybrid-storage case, the shared PCC constraints reduce expected profit, raw-scenario back-test CVaR, and reserve bids by 1.01%, 1.34%, and 18.62%, respectively. Scenario-reduction sensitivity and synthetic price–spread analyses indicate that the main operating mechanisms remain stable within the assumed scenario-generation framework, while sensitivity analyses reveal diminishing returns from CAES expansion and saturation of PCC-related profit gains near 5000 MW. Because all price scenarios are synthetic and neither historical nor independent out-of-sample market data are used, these analyses constitute model-based robustness tests rather than seasonal or real-market validation. The findings support the coordinated configuration of heterogeneous storage, grid-interface capacity, and risk preferences, but should be interpreted as market-bidding-level comparative evidence under the adopted equivalent CAES representation rather than as market-specific profitability forecasts. Full article

Hydrogen (H₂) has emerged as a promising sustainable energy vector due to its scalability, high energy density, and its ability to enable sector coupling across electricity, heating, transportation, and industry. There remains a huge technical challenge to overcome. The economic implications of low round-trip efficiency, high capital costs, the limited lifespan of fuel cells and electrolyzers, and infrastructure constraints on H₂’s relative competitiveness have not been comprehensively studied. In a comparative assessment against other storage options such as batteries, pumped hydro, and compressed air energy storage (CAES), we highlight the potential of H₂ as a grid-scale storage solution. The novelty of this paper is that it compares H₂ as a competing option with other storage technologies and highlights its unique suitability for seasonal and grid-scale applications where others fall short. The paper also discusses the technological opportunities for AI and other digital technologies in the H₂ grid. Unlike general reviews, this work emphasizes the engineering performance of H₂’s production cost and economic viability, electrolyzer technology maturity, infrastructure readiness, safety and lifecycle considerations, and provides critical synthesis and implications. With this, the paper extends beyond the theoretical capacity for H₂ and gives an engineering-focused analysis that informs the drive toward sustainable and resilient power grids. Full article

This study presents an integrated diabatic compressed air energy storage (D-CAES)–cascade organic Rankine cycle (ORC)–liquefied natural gas (LNG) polygeneration system that simultaneously delivers electricity, district cooling, and pipeline-grade natural gas. The D-CAES turbine exhaust serves as the primary heat source for a cascade ORC employing a zeotropic working-fluid mixture, while the LNG warming curve provides a cryogenic condensation sink uniquely suited to glide-matched condensation of the zeotropic condenser. A four-criterion (4E) framework is applied at the component level, yielding four global performance metrics: exergy round-trip efficiency (ERTE), total annualized cost rate (Ż_tot), CO₂ emission factor (ζ_CO2), and net discharge power. A surrogate-assisted multi-objective optimization is developed in which 1000 Latin-hypercube-sampled high-fidelity simulations train three independent artificial neural network (ANN) surrogate models, which are then coupled with the optimization algorithm. The TOPSIS-selected compromise solution achieves an ERTE of 47.55%, a total cost rate of 293.75 USD h⁻¹, and a CO₂ emission factor of 166.98 kg MWh⁻¹. Sensitivity analysis demonstrates that turbine inlet temperature and charging pressure are the dominant thermoeconomic drivers. Full article

The sealing performance of compressed air energy storage (CAES) caverns represents a multi-physics challenge involving coupled thermal–hydraulic–mechanical processes, characterized by complex interacting factors. As a critical determinant of the long-term operational efficiency of CAES facilities, this study developed a fiber-reinforced cement-based composite sealing material through systematic orthogonal experiments investigating four key parameters: water–cement ratio, sand ratio, fly ash–silica fume content, and basalt fiber content. An optimized mixture was formulated with a water–cement ratio (0.36), sand ratio (42%), fly ash–silica fume content (22%), and basalt fiber content (1.0%). Under this optimal mix proportion, the measured permeability coefficient of the sealing layer is 1.92 × 10⁻¹³ cm/s, and the uniaxial compressive strength and tensile strength are 37 MPa and 3.9 MPa, respectively, with a corresponding elastic modulus of 18 GPa. Meanwhile, the P-wave velocity is approximately 2823 m/s, and the porosity is 0.15, achieving balanced performance in permeability, strength, and porosity. The material was validated in a CAES physical model through gas charge–discharge tests under various operational scenarios for the composite sealing layer-lining-surrounding rock system. Full article

This study presents the design and modeling of a first-of-its-kind experimental prototype integrating a high-temperature air-based Concentrated Solar Power (CSP) receiver with a diabatic Compressed Air Energy Storage (CAES) system. The prototype architecture and operating modes are defined, and a detailed thermal model of an Open Volumetric Air Receiver (OVAR) is developed and optimized, with emphasis on passive mass flow regulation under non-uniform solar flux. At nominal conditions (800 °C), the receiver achieves a predicted thermal efficiency of 81.6%. Transient simulations assess off-design dynamic behavior under realistic conditions, showing sensitivity to solar fluctuations and need for heliostat aiming strategies to reduce thermal non-uniformities and ensure stable outlet temperatures. For the CAES subsystem, a techno-economic analysis identifies high-pressure (300 bar) commercial gas cylinders as the most cost-effective aboveground storage solution, while discharge simulations yield a required storage volume of 4.8 m³. Finally, the complete piping and instrumentation diagram (P&ID) of the integrated system is presented, defining the experimental configuration. Overall, this work establishes the design basis for the future experimental demonstration of hybrid CAES-CSP operation for dispatchable renewable power generation and supports subsequent control development and scale-up analyses. Full article

This study presents an ideal-cycle thermodynamic analysis of an advanced compressed air energy storage (A-CAES) system with single thermal energy storage (TES) and an external heat boost. The additional heat is represented by a solar heat source, although the analysis is equally applicable to other forms of externally supplied thermal energy. Following the classical thermodynamic approach used for ideal cycles such as the Brayton, Otto and Diesel cycles, the objective is to establish analytical relationships and performance bounds for the integrated system rather than to model a specific engineering configuration. Three principal performance measures are examined: the electrical round-trip coefficient of performance (CoP), the marginal thermal coefficient of performance associated with external heat addition, and the overall second-law efficiency. Closed-form analytical expressions are derived for these quantities under idealised but still practically relevant assumptions. The analysis identifies distinct operating regimes governed by the level of external heat input and establishes analytical transition conditions between them. It is shown that external heat addition can substantially increase the round-trip coefficient of performance and lead to high marginal heat-utilisation effectiveness. A rigorous upper bound on the second-law efficiency is also obtained from a complete-cycle exergy analysis, demonstrating consistency with the laws of thermodynamics. The results provide analytical insight into the fundamental thermodynamic structure of solar-assisted A-CAES systems and establish performance bounds that are independent of any particular engineering implementation. Full article

To tackle the intermittency of renewable energy and realize the repurposing of abandoned oil and gas wells, this study proposes a compressed air energy storage (CAES)-based cogeneration system integrated with geothermal energy and abandoned oil and gas wells, and conducts a five-dimensional comprehensive analysis covering exergy, exergoeconomic, exergoenvironmental, economic and environmental performance. The optimal operating parameters are determined as air compressed to 200 bar, an ORC turbine inlet pressure of 16 bar and an inlet temperature of 110 °C. The system’s annual total power generation is 2,971,416.5 kWh during low-power daytime operation, and 20,131,785 kWh during high-power nighttime operation. Compared with conventional CAES systems, the proposed system reduces total exergy destruction by 4121.35 kW and increases exergy efficiency from 48.49% to 63.38%. Coolers, geothermal heat exchangers and compressors are the main sources of exergy destruction cost and capital investment, while COM1, HE1 and HOT1 are the key components causing environmental impacts. The system realizes cogeneration of power, hydrogen and pure water, with a static payback period of about 5.4 years and significantly reduced TEWI value at elevated turbine inlet pressure. This system achieves multi-objective synergies in energy efficiency, economy and environment, providing a feasible scheme for the green repurposing of abandoned oil and gas wells and cascaded utilization of renewable energy. Full article

At present, research on the long-term stability of multi-cavern coordinated injection–production operations for salt cavern compressed air energy storage (CAES) remains limited. Large-capacity energy storage utilizing multiple interconnected salt caverns has become an inevitable development trend for modern CAES power stations, highlighting the necessity and importance of stability evaluation and design optimization for underground salt cavern storage clusters. Based on the Anning 350 MW CAES demonstration project, this paper takes the abandoned salt caverns of the project as research objects. A three-dimensional geological and cavern model is established using the FLAC3D numerical simulation method, and stability analysis is carried out under static conditions and three long-term gas injection and production scenarios (the pressure conditions are provided by ground-based equipment). The characteristics of the plastic zone, displacement, stress distribution, and volume shrinkage of the caverns are systematically investigated. The results show that under static conditions, the internal pressure significantly controls the development of the plastic zone, and the caverns are generally stable at pressures above 4 MPa. During long-term operation, the plastic zones of each cavern gradually expand, displacements accumulate continuously, and stresses tend to stabilize after an initial accumulation period. After 30 years of operation, no through-going plastic zones appear in any cavern, and all volume shrinkage rates are below 30%. Among the three cases, Case 1 exhibits the best stability, while enhanced monitoring is required for local high-stress regions in Case 3. This study verifies that the salt cavern development for the Anning CAES project is safe and controllable during long-term operation. The layout spacing of caverns is reasonably designed and fully satisfies the stability requirements of salt cavern CAES power stations. The research results can provide a technical guarantee for the construction of the first CAES power station in Yunnan Province and also offer a reliable reference for the design and construction of similar multi-cavity salt cavern CAES projects. Full article

Against the background of global carbon reduction initiatives and ongoing energy transition, this study addresses the technical challenges of constructing salt cavern storage facilities in bedded salt formations. Typical bedded salt rocks in Southwest China were taken as the research object, and systematic core sampling and multi-dimensional laboratory tests were conducted to investigate their geomechanical and petrophysical properties. The tests included mechanical experiments such as direct shear, uniaxial and triaxial compression, as well as physical property measurements including permeability, porosity, SEM, XRD, and mercury intrusion porosimetry (MIP). The results show that halite exhibits excellent plasticity and tight sealing performance, interlayers have high compressive strength, and mudstone is characterized by significant brittleness. All lithologies possess low permeability and dense internal structures. For this reason, they are well suited for salt cavern energy storage utilization. Furthermore, the research findings provide key basic data and a solid scientific basis. This study supports the construction of salt cavern gas storage and compressed air energy storage (CAES) plants in bedded salt rock areas. Full article

Salt cavern Compressed Air Energy Storage (CAES) is one of the critical technologies for energy storage and an important infrastructure supporting the construction of new power systems and facilitating the achievement of the dual carbon goals. The salt rock resources in China are primarily composed of continental strata salt rocks, characterized by high heterogeneity, well-developed thin-layer interbedding, dissolution resistance among different lithologies, and significant creep variations. These features, to some extent, limit the improvement of wellbore construction accuracy, the reliability of abandoned well sealing, the safety of natural gas storage operations, and enhancements in gas injection–brine displacement efficiency. This study takes the continental bedded salt rock in the Dawenkou Basin as the research object and adopts a method combining theoretical analysis and field engineering verification to improve the systematic construction technology system, covering the whole process of drilling engineering, abandoned well plugging, the design of an injection and brine extraction device, and gas injection and brine drainage. The research results optimize four key technologies, including precise wellbore trajectory control, dual-section milling, and multi-stage redundant plugging of abandoned wells and long-term anti-corrosion completion with laser cladding, and dual-mode adaptive gas injection and brine drainage, and improve the technical system from wellbore construction to salt cavity formation. This study can provide valuable theoretical references and engineering demonstration guidance for underground space development projects in similar salt basins in China. Full article

Underground Compressed Air Energy Storage (CAES) is a promising large-scale energy storage technology, yet its long-term operational safety is constrained by progressive tensile damage accumulation in lining structures under cyclic thermo-mechanical loading. Conventional steel-lined caverns are costly, while ordinary reinforced concrete linings require excessive reinforcement due to their limited tensile capacity, compromising the economic viability of CAES. This study proposes a Reinforced-Steel Fibre Concrete (R-SFC) lining as the structural load-bearing layer of CAES caverns, in which the steel fibres provide tensile and crack-propagation resistance and the rebars contribute supplementary tensile capacity. A 2D coupled thermo-mechanical damage-plasticity finite element model was developed in COMSOL Multiphysics and verified using published in situ monitoring data from operating CAES caverns. Parametric analyses of the steel fibre volume fraction, lining thickness, rebar diameter, and cavern diameter were then performed. The results show that the R-SFC lining significantly improves crack propagation resistance, reducing the maximum tensile damage by 41.3% relative to conventional reinforced concrete while lowering steel consumption. Within the lining–rock system, the concrete lining and the surrounding rock jointly resist the radial compressive load, while the steel fibres and rebars bear the hoop tensile stress. A thickness-to-diameter ratio of 1/8 to 1/5 is identified as the recommended geometric design range to balance lining damage against surrounding rock loading. Finally, an MOPSO algorithm coupled with a PSO-BP surrogate model is employed to balance lining tensile damage against cavern dimensions, yielding optimised parameter combinations particularly suitable for cavern diameters around 4 m. The study findings may provide a new lining solution and design reference for cost-effective and high-reliability underground gas storage. Full article