Search Results (92)

As a pivotal technology and infrastructure component for modern power systems, energy storage has experienced significant advancement in recent years. A fundamental prerequisite for designing future energy storage facilities lies in the systematic evaluation of energy conversion capabilities across diverse storage technologies. This study conducted a comparative analysis between pumped hydroelectric storage (PHS) and compressed air energy storage (CAES), defining the concepts of height exergy and temperature exergy. Height exergy is the maximum work capacity of a liquid due to height differences, while temperature exergy is the maximum work capacity of a gas due to temperature differences. The temperature exergy represents innovation in thermodynamic analysis; it is derived from internal exergy and proven through the Maxwell relation and the decoupling method of internal exergy, offering a more efficient method for calculating energy storage capacity in CAES systems. Mathematical models of height exergy and temperature exergy were established based on their respective forms. A unified calculation formula was derived, and their respective characteristics were analyzed. In order to show the meaning of temperature exergy more clearly and intuitively, a height exergy model of temperature exergy was established through analogy analysis, and it was concluded that the shape of the reservoir was a cone when comparing water volume to heat quantity, intuitively showing that the cold source had a higher energy storage density than the heat source. Finally, a typical hybrid PHS–CAES system was proposed, and a mathematical model was established and verified in specific cases based on height exergy and temperature exergy. It was demonstrated that when the polytropic exponent n = 1.2, the theoretical loss accounted for the largest proportion, which was 2.06%. Full article

The air injection for brine drainage affects the thermodynamic characteristics of salt caverns in the operation of compressed air energy storage (CAES). This study develops a thermodynamic model to predict temperature and pressure variations during brine drainage and operational cycles, validated against Huntorf plant data. Results demonstrate that increasing the air injection flow rate from 80 to 120 kg/s reduces the brine drainage initiation time by up to 47.3% and lowers the terminal brine drainage pressure by 0.62 MPa, while raising the maximum air temperature by 4.9 K. Similarly, expanding the brine drainage pipeline cross-sectional area from 2.99 m² to 9.57 m² reduces the total drainage time by 33.7%. Crucially, these parameters determine the initial pressure and temperature at the completion of brine drainage, which subsequently shape the pressure bounds of the operational cycles, with variations reaching 691.5 kPa, and the peak temperature fluctuations, with differences of up to 4.9 K during the first cycle. This research offers insights into optimizing the design and operation of the CAES system with salt cavern air storage. Full article

The transition toward a renewable-based energy structure has significantly accelerated the advancement of energy storage technologies. Compressed air energy storage (CAES) is regarded as a highly promising long-duration energy storage solution due to the advantages of its large scale and long service life. However, the efficiency of conventional compressed air energy storage (CAES) systems remains limited due to the inadequate utilization of thermal energy. Isothermal compressed CAES (ICAES) technology, based on liquid pistons, can overcome the efficiency bottleneck by enabling temperature control during air compression. However, the operation of liquid pistons under high-pressure storage conditions remains a challenge because of the high compression ratio. To enhance the utilization rate of the two-stage liquid piston unit by using the synchronous operations of compression and discharge processes, this paper proposes a coordinated operation scheme. Then, a multi-stage ICAES system under constant-pressure air storage is proposed. Mathematical models and energy efficiency analysis methods of the multi-stage ICAES system are also established. Finally, the operational characteristics are analyzed in combination with the ICAES at 200 kWh. The results show that the proposed system can achieve an overall efficiency of 68.0%, under 85% and 90% efficiencies for low-pressure and linear equipment, respectively. The coordinated operation of the two-stage liquid piston unit can be further extended to multi-stage operations, demonstrating broad application prospects in ICAES systems. Full article

Compressed air energy storage (CAES) systems represent a critical technological solution for addressing power grid load fluctuations by generating electrical power during peak load periods and storing energy during low load periods. As a prominent branch of CAES, isothermal compressed air energy storage (ICAES) systems have attracted significant research attention due to their elimination of requirements for high-temperature storage chambers and high-temperature compressors. Implementing constant-pressure operation in air storage reservoirs not only enhances energy storage density but also improves system safety. However, existing constant-pressure air storage methodologies necessitate supplementary infrastructure, such as high-pressure water reservoirs or elevated hydraulic columns, thereby escalating capital expenditures. This study introduces a novel constant-pressure air storage strategy for ICAES systems utilizing a linear-driven liquid piston mechanism. The proposed approach achieves constant-pressure air storage through the dual-mode operation strategies of buffer tanks (CBA and CBP modes) and hydraulic cylinders (CPP and CPW modes), eliminating the requirement for an auxiliary high-pressure apparatus or extensive civil engineering modifications. A prototype two-stage constant-pressure ICAES architecture was proposed, integrating low-pressure equipment with liquid pistons and providing detailed operational processes for preconditioning, energy storage, and power generation. A comprehensive mathematical model of the system is developed and validated through process simulation and performance characterization of a 100 kWh capacity system. It demonstrates that under operational conditions of 1 MPa of low pressure and 5 MPa of storage pressure, the system achieves an efficiency of 74.0% when the low-pressure equipment and liquid piston exhibit efficiencies of 85% and 90%, respectively. Furthermore, parametric analysis reveals a negative correlation between system efficiency and low-pressure parameters. Full article

Selecting the type of lined rock cavern (LRC) is a critical aspect in the construction of compressed air energy storage (CAES) plants. Present research on CAES has mainly focused on site selection, sealing performance, and stability of underground LRCs. Insufficient attention has been given to the selection of LRC type, which is a prerequisite for further detailed analyses of LRCs. To overcome this limitation, based on reliable numerical simulation, in this study, we simulate the mechanical responses of two popular types of LRCs: tunnel-type and silo-type LRCs. Parameter sensitivity analysis is then conducted based on the mechanical response, including parameters such as the deformation modulus of the surrounding rock mass, Poisson’s ratio, cohesion, friction angle, crustal stress, and lateral stress coefficient. Based on the simulated results, the analytical hierarchy process (AHP) method is used to propose scoring systems for the two types of LRCs. This scoring system can be used for quantitative estimation of an appropriate LRC in CAES systems. Full article

We analyzed the performance and financial feasibility of a compressed air energy storage (CAES) system in a potential region in Miaoli County, Taiwan, with the aquifer in the underground structure. We conducted a performance analysis of the system using the commercial software Flownex 9.0. Initially, a model for the Huntorf case in Germany was built, and its performance was compared with others for validation. The calculation results showed a deviation of about 1% in terms of efficiency, confirming the analytical capabilities and accuracy of the model. After verifying the system performance, the scale of output power was adjusted to 2 MW for initial development and subsequent planning. Then, geological characteristics were analyzed using COMSOL to establish a multiphase flow analysis model. This model evaluated the flow rate and pressure required for the operation of the CAES system. Lastly, a financial analysis was conducted based on the obtained results. The cost for system components was estimated, and the levelized cost of the proposed CAES system was evaluated. A comparison with other energy storage technologies was conducted to assess the financial feasibility of the analyzed CAES system. Full article

Energy storage systems are gaining increasing attention as a solution to the inherent intermittency of renewable energy sources such as solar and wind power. Among large-scale energy storage technologies, compressed air energy storage (CAES) stands out for its natural sealing properties and cost-efficiency. Having abundant salt resources, the thick and regionally extensive salt deposits in Unit B of Southern Ontario, Canada, demonstrate significant potential for CAES development. In this study, optimization for essential CAES salt cavern parameters are conducted using geological data from Unit B salt deposit. Cylinder-shaped and ellipsoid-shaped caverns with varying diameters are first simulated to determine the optimal geometry. To optimize the best operating pressure range, stationary simulations are first conducted, followed by tightness evaluation and long-term stability simulation that assess plastic and creep deformation. The results indicate that a cylinder-shaped cavern with a diameter 1.5 times its height provides the best balance between storage capacity and structural stability. While ellipsoid shape reduces stress concentration significantly, it also leads to increased deformation in the shale interlayers, making them more susceptible to failure. Additionally, the findings suggest that the optimal operating pressure lies between 0.4 and 0.7 times the vertical stress, maintaining large capacity and minor gas leakage, and developing the least creep deformation. Full article

A high-pressure centrifugal compressor with a shroud cavity is a key piece of energy equipment found in a compressed air energy storage (CAES) system. The leakage flow of the shroud cavity is an important factor affecting the efficiency of the system. Using systematic numerical studies, the influence of leakage flow on high-pressure centrifugal compressors under different leakage rates has been comprehensively elucidated. The study reveals that the leakage flow significantly increases the circumferential swirl angle of the flow at the impeller inlet, thereby exerting a significant influence on the flow characteristics within the impeller. As the leakage rate increases, the stable operating range of the compressor is significantly reduced, with the total pressure ratio decreasing by up to 2% and the isentropic efficiency dropping by up to 4 percentage points. Full article

The increase in the exploration of renewable energy sources intensifies the need for efficient storage solutions to mitigate the inherent intermittence of these sources. Among the available technologies, cryogenic energy storage (CES) systems stand out as a major and promising technology due to their high scalability, energy efficiency, and potential for integration with other systems. This paper deals with cryogenic approaches, focused on Liquid Air Energy Storage (LAES). Several topics are addressed, including the characterization of the CES systems, their working principle, with special relevance to efficiency and temperature/entropy diagram, the conception and the technical challenges, design, and construction of CES. LAES demonstrates energy efficiencies ranging from 45% to 70%, potentially reaching up to 75% with the integration of complementary technologies, with capital costs ranging from 900 EUR/kW to 1750/EUR/kW. Carbon dioxide (CO₂)-based systems, while more energy-efficient (40% to 60%), face significant barriers due to high infrastructure costs. Additionally, hybrid configurations that combine advanced thermal cycles and waste heat management achieve efficiencies between 55% and 80%, showing adaptability in complex energy scenarios. In comparison with alternatives such as batteries and Compressed Air Energy Storage (CAES), despite economic and technological limitations, CES systems have a promising role in the global energy transition, particularly with anticipated advancements that will enhance their competitiveness and economic viability. Full article

This paper focuses on the critical role of long-duration energy storage (LDES) technologies in facilitating renewable energy integration and achieving carbon neutrality. It presents a systematic review of four primary categories: mechanical energy storage, chemical energy storage, electrochemical energy storage, and thermal energy storage. The study begins by analyzing the technical advantages and geographical constraints of pumped hydro energy storage (PHES) and compressed air energy storage (CAES) in high-capacity applications. It then explores the potential of hydrogen and synthetic fuels for long-duration clean energy storage. The section on electrochemical energy storage highlights the high energy density and flexible scalability of lithium-ion batteries and redox flow batteries. Finally, the paper evaluates innovative advancements in large-scale thermal energy storage technologies, including sensible heat storage, latent heat storage, and thermochemical heat storage. By comparing the performance metrics, application scenarios, and development prospects of various energy storage technologies, this work provides theoretical support and practical insights for maximizing renewable energy utilization and driving the sustainable transformation of global energy systems. Full article

The reversible use of a volumetric machine as a compressor and expander shows potential for micro-scale compressed air energy storage systems because of lower investment costs and higher operational flexibility. This paper investigates experimentally the reversible use of a 3 kW oil-flooded twin-screw compressor as an expander for a micro-scale compressed air energy storage system to assess its operation while minimizing operating costs and the need for adjustments. As a result, the oil injection was only implemented in the compressor operation since the oil takes part in the compression process, while its use appears optional in expander operation. The results indicate that the compressor exhibited an efficiency in the range of 0.57–0.80 and required an input power from 1 kW up to 3 kW. These values decreased for the expander, whose efficiency was in the range of 0.24–0.38 and the delivered power between 300 and 1600 W. The experimental data allow assessing the operation of such machine in a hypothetical micro-scale compressed air energy storage. The calculation revealed that this machine may operate in this energy storage asset and deliver up to 90% of the power recovered in the charging process when the temperature of the stored air is 80 °C. Full article

Integrated energy systems (IESs) have been implemented with the objective of enhancing the efficiency of energy utilization and facilitating the sustainable transition of society and energy systems. To further explore the multi-energy coupling capacity and carbon reduction potential of the IESs, this study presents the design of an integrated cold-electricity-heat energy system (ICEHS) with advanced adiabatic compressed air energy storage (AA-CAES). AA-CAES has the capacity to not only store and release electric energy, but also to provide cold and heat energy, which makes it an ideal choice for this application. The main work of this study is fourfold: (1) the energy hub concept is employed to describe the energy transformations within AA-CAES, thereby reducing the modeling complexity; (2) integrated demand response (IDR) for cooling, heating, and electric loads, including shiftable loads, adjustable loads, interruptible loads, and replaceable loads, is considered; (3) Latin hypercubic sampling in conjunction with K-means clustering is employed to address the issue of source-load uncertainty; and (4) an ICEHS operation optimization model is developed with the objective of minimizing the daily operating cost, where the possible cost terms include energy purchase cost, operation and maintenance cost, demand response cost, and carbon emission cost. A typical community integrated energy system is employed as an illustrative example, and four different scenarios are established to validate the effectiveness of the proposed model. The results indicate that AA-CAES and IDR can effectively reduce the daily operating cost and carbon emissions of an ICEHS. In comparison to the scenario that did not incorporate AA-CAES and IDR, the daily operating cost and carbon emissions are reduced by 4.8% and 10.3%, respectively. Full article

Conventional energy storage systems, such as pumped hydroelectric storage, lead–acid batteries, and compressed air energy storage (CAES), have been widely used for energy storage. However, these systems face significant limitations, including geographic constraints, high construction costs, low energy efficiency, and environmental challenges. Among these, lead–acid batteries, despite their widespread use, suffer from issues such as heavy weight, sensitivity to temperature fluctuations, low energy density, and limited depth of discharge. Lithium-ion batteries (LIBs) have emerged as a promising alternative, offering portability, fast charging, long cycle life, and higher energy density. However, LIBs still face challenges related to limited lifespan, safety concerns (such as overheating), and environmental impact due to resource extraction and emissions. This review explores the introduction of nanotechnology as a transformative approach to enhance efficiency and overcome the limitations of LIBs. We provide an in-depth overview of various nanotechnology-based solutions for LIBs, focusing on their impact on energy density, cycle life, safety, and environmental sustainability. Additionally, we discuss advanced thermal analysis techniques used to assess and improve the performance of nanotechnology-enhanced LIBs. Finally, we examine the role of nanoparticles in the environmental remediation of LIBs, offering insights into how they can mitigate the ecological footprint of battery disposal and recycling. This review aims to highlight the potential of nanotechnology to revolutionize energy storage systems and address the growing demand for efficient and sustainable energy solutions. Full article

This research aims to support the goals of Oman Vision 2040 by reducing the dependency on non-renewable energy resources and increasing the utilization of the national natural renewable energy resources. Selecting appropriate energy storage systems (ESSs) will play a key role in achieving this vision by enabling a greater integration of solar and other renewable energy. ESSs allow for solar power generated during daylight hours to be stored for use during peak demand periods. Additionally, the proposed framework provides guidance for large-scale ESS infrastructure planning and investments to support Oman’s renewable energy goals. As the global renewable energy market grows rapidly and Oman implements economic reforms, the ESS market is expected to flourish in Oman. In the near future, ESS is expected to contribute to lower electricity costs and enhance stability compared to traditional energy systems. While ESS technologies have been studied broadly, there is a lack of comprehensive analysis for optimal ESS selection tailored to Oman’s unique geographical, technical, and policy context. The main objective of this study is to provide a comprehensive evaluation of ESS options and identify the type(s) most suitable for integration with Oman’s national grid using a multi-criteria decision-making (MCDM) methodology. This study addresses this gap by applying the Hesitate Fuzzy Analytic Hierarchy Process (HF-AHP) and Hesitate Fuzzy VIKOR methods to assess alternative ESS technologies based on technical, economic, environmental, and social criteria specifically for Oman’s context. The analysis reveals pumped hydro energy storage (PHES) and compressed air energy storage (CAES) as the most appropriate solutions. The tailored selection framework aims to guide policy and infrastructure planning to determine investments for large-scale ESSs and provide a model for comprehensive ESS assessment in energy transition planning for countries with similar challenges. Full article

As the world’s demand for sustainable and reliable energy source intensifies, the need for efficient energy storage systems has become increasingly critical to ensuring a reliable energy supply, especially given the intermittent nature of renewable sources. There exist several energy storage methods, and this paper reviews and addresses their growing requirements. In this paper, the energy storage options are subdivided according to their primary discipline, including electrical, mechanical, thermal, and chemical. Different possible options for energy storage under each discipline have been assessed and analyzed, and based on these options, a handsome discussion has been made analyzing these technologies in the hybrid mode for efficient and reliable operation, their advantages, and their limitations. Moreover, combinations of each storage element, hybrid energy storage systems (HESSs), are systems that combine the characteristics of different storage elements for fulfilling the gap between energy supply and demand. HESSs for different storage systems such as pumped hydro storage (PHS), battery bank (BB), compressed air energy storage (CAES), flywheel energy storage system (FESS), supercapacitor, superconducting magnetic coil, and hydrogen storage are reviewed to view the possibilities for hybrid storage that may help to make more stable energy systems in the future. This review of combinations of different storage elements is made based on the previous literature. Moreover, it is assessed that sodium-sulfur batteries, lithium-ion batteries, and advanced batteries are the most helpful element in HESSs, as they can be hybridized with different storage elements to fulfill electricity needs. The results also show that HESSs outperformed other storage systems and, hence, hybridizing the characteristics of different storage elements can be employed for optimizing the performance of energy storage systems. Full article