Explore the vast range of titles available.

With the increase of power generation from renewable energy sources and due to their intermittent nature, the power grid is facing the great challenge in maintaining the power network stability and reliability. To address the challenge, one of the options is to detach the power generation from consumption via energy storage. The intention of this paper is to give an overview of the current technology developments in compressed air energy storage (CAES) and the future direction of the technology development in this area. Compared with other energy storage technologies, CAES is proven to be a clean and sustainable type of energy storage with the unique features of high capacity and long-duration of the storage. Its scale and cost are similar to pumped hydroelectric storage (PHS), thus CAES has attracted much attention in recent years while further development for PHS is restricted by the availability of suitable geological locations. The paper presents the state-of-the-art of current CAES technology development, analyses the major technological barriers/weaknesses and proposes suggestions for future technology development. This paper should provide a useful reference for CAES technology research and development strategy.

Sustainable manufacturing has received great attention in the last few decades for obtaining high quality products with minimal costs and minimal negative impacts on environment. Sustainable machining is one of the main sustainable manufacturing branches, which is concerned with improving environmental conditions, reducing power consumption, and minimizing machining costs. In the current study, the performance of three sustainable machining techniques, namely dry, compressed air cooling, and minimum quantity lubrication, is compared with conventional flood machining during the turning of austenitic stainless steel (Nitronic 60). This alloy is widely used in aerospace engine components, medical applications, gas power industries, and nuclear power systems due to its superior mechanical and thermal properties. Machining was performed using SiAlON ceramic tool with four different cutting speeds, feeds and a constant depth of cut. Consequently, various chip characteristics such as chip morphology, chip thickness, saw tooth distance and chip segmentation frequency were analyzed with both optical and scanning electron microscopes. Performance assessment was performed under the investigated cutting conditions. Our results show that the tool life under MQL machining are 138%, 72%, and 11% greater than dry, compressed air, and flooded conditions, respectively. The use of SiAlON ceramic tool results is more economically viable under the MQL environment as the overall machining cost per component is lower ($0.27) as compared to dry ($0.36), compressed air ($0.31), and flooded ($0.29) machining conditions. The minimum quantity lubrication technique outperformed the other investigated techniques in terms of eco-friendly aspects, economic feasibility, and technical viability to improve sustainability.

Electrical energy storage systems have a fundamental role in the energy transition process supporting the penetration of renewable energy sources into the energy mix. Compressed air energy storage (CAES) is a promising energy storage technology, mainly proposed for large-scale applications, that uses compressed air as an energy vector. Although the first document in literature on CAES appeared in 1976 and the first commercial plant was installed in 1978, this technology started to gain attention only in the decade 2000–2010, with remarkable scientific production output and the realization of other pre-commercial demonstrators and commercial plants. This study applies bibliometric techniques to draw a picture of the current status of the scientific progress and analyze the trend of the research on CAES and identify research gaps that can support researchers and manufacturers involved in this entering technology. Recent trends of research include aspects related to the off-design, the development of thermal energy storage for adiabatic CAES, and the integration of CAES with combined heating and cooling systems.

The increasing push for renewable penetration into electricity grids will inevitably lead to an increased requirement for grid-scale energy storage at multiple time scales. It will, necessarily, lead to a higher proportion of the total energy consumed having been passed through storage. Offshore wind is a key technology for renewable penetration, and the co-location of energy storage with this wind power provides significant benefits. A novel generation-integrated energy storage system is described here in the form of a wind-driven air compressor feeding underwater compressed air energy storage. A direct drive compressor would require very high intake swept volumes. To overcome this difficulty, some prior compression is introduced. This paper discusses the constituent technologies for this concept, as well as the various configurations that it might take and the logic behind operating it. Special consideration has been given to the differences resulting from utilising a near-isothermal wind-driven compressor versus a near-adiabatic one. Multiple iterations of the system have been simulated. This has been done using a price-matching algorithm to optimise the system operation and using volumetric air flow rates to calculate exergy flow. Simulated operation has been performed for a year of real wind and electricity price data. This work has been performed in order to clarify the relationships between several key parameters in the system, including pressure and work ratios, volumetric flowrates, storage costs and profit rates. An additional objective of this paper was to determine whether the system has the potential for economic viability in some future energy grid, especially when compared with alternative wind and energy storage solutions. The results of the simulation indicated that, with proper sizing, the system might perform competitively with these alternatives. Maximum one-year return on investment values of 9.8% for the isothermal case and 13% for the adiabatic case were found. These maxima were reached with ~15–20 h of output storage. In all cases, it was found that maximising the power of the wind-driven compressor compared with the initial compressor was favourable.

This text explains the use of compressed air for energy storage and efficient pneumatic applications. Chapters cover the elementary physical and engineering principles related to compressed air, including compression and expansion characteristics, adiabatic, polytropic, and isothermal phenomena, and energy content within a given volume. The author also discusses the advantages and drawbacks of pneumatic technology and presents innovative ways to increase the energetic efficiency of pneumatic actuators. A key highlight of the book is the introduction of a method to enhance energetic efficiency by incorporating expansion work alongside constant pressure displacement. The author presents an analysis of various cylinder assemblies where energy efficiency is notably improved compared to conventional pneumatic actuators. The book serves as a primary reference for mechanical engineering students and as a handbook for engineers designing efficient pneumatic devices. Key Features: Fundamental and advanced information about actuators and their pneumatic applicationsFocus on energy efficiency testingSystematic chapter order for effective learning progression, with a working example to support comprehensionReferences for further readingAppendices providing additional insights and resources Readership Mechanical engineering students and engineers working on pneumatics.

This study presents the research and development possibilities of an expander for compressed air energy storage systems (CAES). The computer simulations made by the authors aim to find the optimal working parameters of the piston engine. The criteria for evaluating engine operation and the objects of analysis are the compressed air engine system’s efficiency and the electrical power output. Sensitivity analysis was performed on well-suited system parameters and geometrical sizes of the energy utilisation element. Appropriate selection achieves not only higher efficiency but also allows the system to be scaled to the end-user’s needs.

Mechanical responses induced by temperature and air pressure significantly affect the stability and durability of underground compressed air energy storage (CAES) in a lined rock cavern. An analytical solution for evaluating such responses is, thus, proposed in this paper. The lined cavern of interest consists of three layers, namely, a sealing layer, a concrete lining and the host rock. Governing equations for cavern temperature and air pressure, which involve heat transfer between the air and surrounding layers, are established first. Then, Laplace transform and superposition principle are applied to obtain the temperature around the lined cavern and the air pressure during the operational period. Afterwards, a thermo-elastic axisymmetrical model is used to analytically determine the stress and displacement variations induced by temperature and air pressure. The developments of temperature, displacement and stress during a typical operational cycle are discussed on the basis of the proposed approach. The approach is subsequently verified with a coupled compressed air and thermo-mechanical numerical simulation and by a previous study on temperature. Finally, the influence of temperature on total stress and displacement and the impact of the heat transfer coefficient are discussed. This paper shows that the temperature sharply fluctuates only on the sealing layer and the concrete lining. The resulting tensile hoop stresses on the sealing layer and concrete lining are considerably large in comparison with the initial air pressure. Moreover, temperature has a non-negligible effect on the lined cavern for underground compressed air storage. Meanwhile, temperature has a greater effect on hoop and longitudinal stress than on radial stress and displacement. In addition, the heat transfer coefficient affects the cavern stress to a higher degree than the displacement.

The air storage pressure of compressed air energy storage system gradually decreases during the process of energy release, and a reasonable air distribution method for the turbine is required to make the turbine work efficiently in this process. In this paper, based on the single nozzle governing method, the effect of the variation of the full circumferential relative stator installation angle on the system performance improvement under the rated output work condition is investigated. It is shown that the specific work of the variable relative stator installation angle can be improved by up to 6.3 % relative to the design stator installation angle and up to 15.7 % relative to the throttle governing method under the base pressure of 10.0 MPa. With the same absence of throttling losses, the specific work of 3-nozzle inlets method is higher than that of 4-nozzle inlets method, and the turbine internal losses are reduced by 10.6 %. This study provides a theoretical basis for the design, optimization and operation control of nozzle governing turbines.

Lined rock cavern at shallow depth is identified as a promising alternative and cost-effective solution for air storage of large-scale compressed air energy storage (CAES) plant. To better understand the thermodynamic process of the compressed air in the underground cavern and the response of the surrounding rock during air charging and discharging phases, a small-scale pilot cavern with concrete liner and fiber-reinforced plastic (FRP) sealing layer was constructed in China. The test program includes one trial charging test, eight short-term charging tests, and one long-term charging test. Numerical simulations were carried out along with the experiments. The results show that the air pressure in the pilot cavern increased/decreased approximately linearly during the charging/discharging phase when the air was injected/released at a constant mass rate. The heat exchanging system could maintain the temperature of the compressed air in the cavern in a designed range. Excellent sealing performance of the FRP was validated in the test, with only 3.2% air mass leaked during the high-pressure storage phase. The influence of the high air pressure on the surrounding rock was limited and only elastic deformation was observed in all the tests. Good quality of rock mass could guarantee the structural safety of the underground cavern under high inner pressure. Generally, there are reasonable agreements between the numerical simulation and the results of the experiment. The study confirms the feasibility of CAES in lined rock caverns at shallow depth.

An unmanned underwater vehicle (UUV) powered by a compressed air power system is proposed to address challenges for battery/motor-powered vehicles under high-speed navigation, long endurance, and high mobility. These vehicles actively utilize supercavitation drag reduction by the exhausted gas from the compressed air power system. MATLAB/Simulink and FLUENT are used to establish theoretical models of the compressed air power system and ventilation supercavitation. The relationship between system power and navigation resistance is examined with different air flows, along with a comparison of endurance of different power vehicles at various speeds. The issue of the endurance-enhancing effect of supercavitation at high speed is investigated. The results demonstrate that increasing the air flow leads to higher power and reduced navigation resistance, and there is a balance between them. Furthermore, compared to the battery-powered vehicles with equal energy storage capacity, the compressed air power system shows 210.08% to 458.20% longer endurance times at speeds of 30 kn to 60 kn. Similarly, considering equal energy storage mass, it achieves 42.02% to 148.96% longer endurance times at high speeds (30 kn to 60 kn). The integration of supercavitation and air-powered systems can greatly enhance the endurance and maneuverability of the vehicle at high speeds while ensuring a compact system structure. The investigations could offer valuable ideas for the development and application of compressed air power systems for UUV at 30 kn to 60 kn or higher maneuvering.