At present, the construction technology of salt cavern gas storage has been mature, and it is developing in the direction of intelligence. Based on the technical status of salt cavern gas storage, the current construction technologies of salt cavern gas storage are analyzed. From the perspective of whole life cycle management, the intelligent construction of salt cavern gas storage is divided into four stages: intelligent location, intelligent design, intelligent construction and intelligent operation and maintenance, and the key technologies involved in each stage are studied. The technical framework of intelligent construction technology of salt cavern gas storage and its specific content is put forward. Moreover, the future research focus of intelligent construction of salt cavern gas storage is proposed and summarized from four aspects: system, technology, theory and model. The relevant technologies have been effectively applied in Yingcheng 300 MW compressed air energy storage demonstration project.

Hydrogen storage by physical adsorption offers significant advantages, including high safety, high hydrogen storage density, and fast hydrogen charging and discharging rates, making it a highly promising method for hydrogen storage. Among the various materials, metal-organic frameworks (MOFs) have emerged as ideal hydrogen storage materials due to their highly ordered porous structures and tunable characteristics. To investigate the influence of thermal effects during the hydrogen adsorption process on storage performance, a numerical model of hydrogen storage by adsorption is established and validated. Subsequently, the hydrogen storage properties of Cu-BTC and activated carbon AX-21 tanks are analyzed and compared. Furthermore, the hydrogen storage capacity of Cu-BTC tank at different temperatures is explored. The results indicate that, compared with AX-21, the hydrogen storage capacity at room temperature increases by 12.8% when using Cu-BTC as adsorbent. When the storage temperature is reduced to 77 K, the maximum pressure in the Cu-BTC tank decreases to 0.97 MPa, and the hydrogen storage capacity increases by 174% compared with room temperature (300 K). These findings provide valuable insights for further research on the hydrogen storage capabilities of Cu-BTC materials.

Liquid air energy storage (LAES) technology stands out as a large-scale energy storage technology due to its superior energy storage density and adaptability to external energy sources. An LAES system that recovers waste cold of liquid ethylene and introduces an external low-temperature heat source is proposed. Moreover, thermodynamical and economic analysis on key parameters, including isentropic efficiency of the compressor and expander, and temperature of the heat source, are conducted. The results reveal that, when the ethylene flow rate is 34 t/h, the energy storage capacity can reach up to 5 MW/40 (MW·h). At isentropic efficiency of the compressor and expander of 90%, the round-trip efficiency can achieve 77.45% by solely relying on an ambient heat source of 25 ℃ for air heating. When the heat source temperature is increased to 125 °C, the system’s optimal round-trip efficiency, net present value, and dynamic payback period reaches 106.99%, 144.73 million yuan, and 3.56 years, respectively. These findings provide reference for research on the coupling of LAES systems with external cold energy.

Solid oxide cells have the ability to switch between electrolysis and fuel cell power generating modes, and operate at 650~850 ℃, resulting in high-grade waste heat. The equipment utilization ratio and energy utilization efficiency can be significantly increased by using the cell for the tri-generation of heat, electricity, and hydrogen. A photovoltaic and concentrated solar heat driven solid oxide cell system for tri-generation system of heat, power, and hydrogen is presented, and molten salt thermal storage system and batteries are coupled to ensure continuous and stable operation of solid oxide cell. By taking the lowest total cost as the object, a mixed integer linear programming model for system capacity configuration and operation strategy optimization is constructed. Moreover, based on the energy consumption principle of cascade utilization, the pinch analysis approach is applied to maximize the cascade use of multi-grade energy flows throughout the entire system, providing an efficient mechanism for integrating mass and energy in coupled systems. For a real case of solar energy resources and heat, electricity, hydrogen requirement in an industrial park, the coupled system’s levelized energy cost is 0.28 yuan/kW, and the annual full load operating hours of the solid oxide cell reaches over 6 000 h.

The arrangement of micro adiabatic compressed air energy storage (A-CAES) system is flexible and suitable for typical distributed energy systems. By accurately modelling a typical device of the miniature A-CAES system based on pneumatic motors, a thermodynamic model that can reflect its system performance is constructed. The experimental bench of the A-CAES system is built, and the average error rate between the simulation model and the experiment is around 5.38%, which verifies the reliability of the model. The round-trip efficiency and comprehensive efficiency of the system are 4.81% and 27.23%, respectively, verifying the necessity of the existence of thermal energy storage devices in the A-CAES system. The effects of compression level and compression ratio on the system performance are analyzed by using this model. The results show that, as the compression level increases, the round-trip efficiency and comprehensive efficiency of the system both increase, and the optimal efficiency of the system can reach 6.10% and 35.81%, respectively. Taking the combination of compression ratios of 2, 3, and 5 as an example, reasonable distribution of compression ratios can improve the round-trip efficiency and overall efficiency of the system by 1.27% and 4.38%, respectively.

To explore the heat and mass transfer process in a solid-state hydrogen storage reactor, a two-dimensional numerical calculation model for the reactor is developed. The radial reaction rate distribution characteristics of the solid-state hydrogen storage material within the reactor is investigated, and the influence laws of bed thickness of the hydrogen storage material and diameter of the heat exchange tube on saturation radius are also studied. Based on this, the arrangement of the heat exchange tube bundle is optimized. The results show that, the heat exchange tube has the corresponding maximum saturation radius, and it increases with the tube radius. When the tube radius is 1.00~6.00 mm with single-tube arrangement, the maximum saturation radius is 2.60, 3.30, 3.50, 3.70, 3.80 and 3.90 mm, respectively. The volume fraction of heat exchange tubes with radius of 1.00, 2.00 and 3.00 mm is relatively small, which is 7.72%, 14.24% and 21.30%. The optimal bed thickness between tubes is 4.86, 6.09 and 6.38 mm when arranging the above three types of tubes in a tube bundle. Moreover, adding heat exchange tube bundles can effectively improve the hydrogen storage performance of reaction dead zone in the reactor. In the reactor equipped with heat exchange tube bundles with radius of 2.00 mm, adding 12 heat exchange tubes with radius of 2.00 mm in the reaction deadzone can reduce the hydrogen storage time to 267 s (by 40.00%), while the volume fraction of tube bundle only increases by 1.92%, and the hydrogen storage capacity just decreases by 2.17%. The research findings can establish a fundamental basis for the optimal design of solid-state hydrogen storage reactors and offer valuable guidance for subsequent engineering applications.

Accelerating the transformation of energy structure and promoting the grid connection of renewable energy power generation is an important initiative to address climate change and the development of renewable energy. Energy storage technology can improve the stability of power grid and enhance the utilization rate of renewable energy. Among the energy storage technologies, compressed air energy storage has been widely studied for its high efficiency, low investment cost and environmental friendliness. Compared with the conventional constant-capacity compressed air energy storage technology, isobaric compressed air energy storage avoids the unavoidable buffer air in the constant-capacity compressed air energy storage system, enables the compressor and expander to operate efficiently at constant discharge pressure, and eliminates the throttling loss in front of the expander unit. The advantages of isobaric compressed air energy storage technologies are introduced, and the isobaric compressed air energy storage technologies are classified into underwater compressed air energy storage, pumping-compensated compressed air energy storage, solid-compensated compressed air energy storage, and gas-phase-change-compensated compressed air energy storage. Moreover, the basic principles, research progress and challenges of the above four types of isobaric compressed air energy storage technologies are discussed. Finally, the development of the isobaric compressed air energy storage technologies is prospected.

Affected by the rapid electricity load growth and the increase of water uncertainty under extreme weather conditions, the contradiction between supply-side and demand-side volatility in areas with high hydropower proportion has become increasingly prominent. The demand for flexible resources with long-term regulation capability is becoming more urgent. Hydrogen energy storage with long-term regulation capacity can alleviate the tense situation of supply and demand in areas with high proportion of hydropower. The research designs an optimal allocation model of electric-hydrogen hybrid energy storage, which is suitable for areas with high hydropower proportion. The loss of load penalty function is introduced into the objective function, and the variation of generation capacity of large/small and medium-sized hydropower units with time is quantified. By taking the power system composed of 96 different types of generators in a high hydropower proportion area as the object, analysis is performed. Compared with the current energy storage configuration requirements, the optimization result of the model increases the hydropower consumption by 7 188 MW·h, reduces the unloaded electricity by 6 513 MW·h, and reduces the total cost by 3.194 million yuan. Moreover, the demand scale of different types of energy storage and the income of energy storage enterprises in high hydropower area, high thermal power area and high new energy area are compared horizontally. The relevant conclusions can provide reference for the development of energy storage investment in the future.

Liquid air energy storage (LAES) is a promising technology for large-scale energy storage due to its geographical flexibility and high energy storage density. To further improve the round-trip efficiency and economic benefits of LAES, a novel integrated system combining liquid natural gas (LNG) cold energy utilization and organic Rankine cycle (ORC) with LAES is proposed. Thermodynamic and economic analysis methods for the integrated system are established, and the effects of key parameters on the system’s thermal performance are investigated based on simulations. An economic analysis of the system is also conducted. The results show that, as the system’s expansion pressure increases, both efficiency and power output rise, but at a decreasing rate. The system’s round-trip efficiency increases with more expansion stages up to a point, then decreases. With four-stage expansion, the system efficiency reaches 62.26%, which is 7%~12% higher than that of the conventional LAES system. When the difference between peak and valley electricity prices is 0.848 yuan/(kW·h), the net present value, dynamic payback period, and levelized cost of electricity are 119 058 500 yuan, 4.48 years, and 0.893 yuan/(kW·h), respectively. The results of this study can provide a reference for engineering application and efficiency improvement of LAES systems.

The compressed air energy storage is a large-scale physical energy storage technology and a highly promising new type of energy storage technology. This paper summarizes the basic principles of isothermal compressed air energy storage, and introduces the principles and current development status of key equipment and related technologies. It provides an analysis and summary of liquid pistons, pumps and turbines. Moreover, it reviews the basic principles of isothermal compressed air energy storage, and analyzes the existing research progress on isothermal compressed air energy storage technology. An analysis and summary are presented for liquid piston technology, as well as pump and turbine technology in the system. The data of existing compressed air energy storage power stations are summarized and analyzed. The data of existing compressed air energy storage power stations are summarized and analyzed. On this basis, the future development direction of isothermal compressed air energy storage technology is prospected, which provides a certain data reference for the selection of power equipment in isothermal compressed air energy storage system and the promotion of demonstration projects.