Latent heat thermal energy storage technology can realize recovery and supply of heat during solid-state hydrogen storage and release process, achieving self-thermal balance inside the solid-state hydrogen storage tank, and improve the hydrogen storage and release performance. For horizontal tube and shell latent heat thermal energy storage exchanger, a new movement method where the inner tube is placed eccentrically to rotate around the central axis is proposed. By the Fluent software, the user-defined function UDF is written using the dynamic mesh technique, and the influence of eccentric distance and rotation velocity of the inner tube on heat storage performance is focused. The results show that, compared with the conventional static arrangement of the central inner tube, the rotation movement of the eccentric inner tube can improve the heat storage performance significantly. The heat storage time reaches the shortest when the eccentric distance is 9 mm and the rotation velocity is 0.10 r/min, namely decreases by 92.16%, and the time average heat storage rate increases by 11.51 times. The heat storage time reduces by 13.57% when the eccentric distance is 9 mm and the rotation velocity is decreased from 0.30 r/min to 0.1 r/min, it decreases by 70.48% when the rotation velocity is 0.10 r/min and the eccentric distance is increased from 3 mm to 9 mm. The study results can provide a new idea for performance optimization of horizontal shell and tube latent heat thermal energy storage exchangers in hydrogen storage field.

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.

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.

In order to reduce the fluctuation of renewable energy power generation output and improve the utilization rate of renewable energy, this paper designs an on/off grid wind solar hybrid hydrogen synthesis ammonia system. Taking the maximum annual revenue of the system as the objective function, considering the operation constraints such as power balance, hydrogen balance and grid interaction, a capacity allocation scheduling optimization model is established. Taking the real output of the wind and solar energy in a certain area of Inner Mongolia as the input, through the analysis on wind and solar energy capacity ratio, this paper explores the technical and economic effect of the wind and solar energy capacity ratio on the system. The results show that, after the capacity configuration and scheduling optimization of the on/off grid wind solar complementary hydrogen and ammonia system, the system can reasonably switch the working state under different wind and solar output conditions, stabilize the wind and solar fluctuations, and realize the stable and efficient operation of ammonia equipment. The grid connected system is better than the off grid system. Through the analysis of the ratio of wind and solar capacity, in the case area, with the increase of wind capacity, the capacity of electrolyzer and hydrogen storage tank to be configured in the system shows a trend of first decreasing and then increasing. When the capacity of wind power generation and photovoltaic power generation is close to or equal, the economic efficiency of the system is high.

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.

As a large scale of physical energy storage technology, compressed air energy storage technology is widely used in consumption of renewable energy and peak shaving of power grids. A compressed air energy storage system coupled with molten salt thermal storage is designed, and the composite system is modeled using Ebsilon software. Based on the operating conditions of the energy storage system supplying hot water, steam, and electricity, the exergy efficiency, thermal efficiency, and economic performance under different operating modes are studied. The results indicate that, the composite system achieves the highest exergy efficiency (64.98%) at a storage pressure of 7 MPa and an exhaust temperature coefficient of 1.96. The highest thermal efficiency (91.55%) is attained at a storage pressure of 12 MPa. In the application scenario of combined heat, steam, and electricity cogeneration, the optimal energy storage duration is 6 hours. Additionally, at gas storage pressures of 7 MPa and 12 MPa, the optimal power generation durations are 6 hours and 8 hours. This research provides theoretical guidance for the study of cogeneration of power and heating using compressed air energy storage system coupled with molten salt thermal storage system.

The stability and cost-effectiveness of power supply has been a pressing issue in areas such as isolated islands where power resources are relatively scarce and natural resources is abundant. Conventional stand-alone microgrids mostly rely on the non-dominated sorting genetic algorithm (NSGA-II) for capacity allocation, which has slightly insufficient local search capability when dealing with multi-objective optimization problems with real loads. In order to overcome this limitation, the improved strength Pareto evolutionary algorithm (SPEA2) is used to optimize the capacity allocation of wind-PV-diesel-battery stand-alone microgrid, which takes the economic cost, loss-of-load probability, and carbon emission as the optimization objectives, to achieve a more comprehensive and efficient capacity allocation. By importing the weather and load data of an isolated island and generating the real Pareto frontier of the independent microgrid with wind, PV, diesel and storage, the analysis results of SPEA2 are compared with that of multi-objective search based on indicator selection (IBEA) and NSGA-II algorithms. Compared with the NSGA-II algorithm, the anti generational distance evaluation IGD index of the SPEA2 increases by 46.83%, the spatial evaluation method Spacing index rises by 60.28%, and the real Pareto coverage CPF index grows by 35.14%, indicating the SPEA2 shows a more excellent performance. Finally, the parameters of each part are reasonably configured according to the results of capacity optimization. It shows that the joint output meets the load demand, which provides a new way of thinking for the energy management of isolated islands and other areas with scarce power resources, and also provides a valuable reference for the optimal design of multi-energy microgrids.

A double-layer optimization site selection method for energy storage with grid-forming demand in novel power system is proposed, which considers the response of energy storage to peak shaving and frequency regulation in the power system and establishes a multi-objective double-layer optimization model. The operation layer counts the wind and solar power abandonment and network losses into the economic penalty, and takes the optimal annual operating cost of the system as the objective, considers the benefits of peak shaving and frequency modulation. The planning layer evaluates the security of the system and models the system by taking the optimal comprehensive annual operating cost of the system as the objective. Simulation and analysis of the algorithms are carried out using the improved empire competition algorithm. The peaking and frequency regulation economics and energy storage siting in the optimal scenario are illustrated through multi-scenario comparisons. Finally, the IEEE-33 node arithmetic system is simulated and analyzed to verify the validity of the proposed model. Furthermore, uncertainty factor indicators are selected to conduct sensitivity analysis on total costs, and the indicators that need more attention to affect economic costs are determined.

Against the conflict between carbon emission and operation cost in integrated energy systems, a multi-objective optimal scheduling method for wind-solar-thermal-storage integrated energy system considering carbon capture is proposed. It explores how carbon capture equipment affects the renewable energy consumption, carbon emissions, and operating costs. Taking the electric load data of a typical day in a specific area as a reference and the improved IEEE 30-bus system as the example, the system economy is optimized. The results show that, compared with the wind-solar-thermal and wind-solar-thermal-storage scenarios without carbon capture, the operating costs of the integrated energy system considering carbon capture reduces by 5.19% and 2.86% respectively on typical days, and the carbon emissions decrease by 1 159 t and 1 013 t, respectively. The consumption rate of wind and solar power generation increases by 5.01% and 2.82%, respectively. Moreover, with the minimum system operation cost and carbon emissions as the optimization objectives, the non-dominated sorting genetic algorithm II is used for multi-objective optimization, and the system scheduling optimization scheme under different target weights is obtained by combining with the linear weighted sum method. The study finds that, increasing the weight of carbon emission target reduces the carbon emissions but raises the system operation costs and the cost per unit of carbon emission reduction. Specifically, when the target weight of carbon emissions rises from 0 to 0.5, the carbon emissions decrease by 5 159 t and the operating costs increase by 205 466 yuan. The carbon emission reduction cost per unit increases the least when the target weight shifts from 0.4 to 0.5. The most significant emission reductions occur when the target weight is within [0.2, 0.4]. The multi-objective optimal scheduling method considering carbon capture proposed above provides a reference for decision makers when weighing system carbon emissions and operating economy.

With the deepening of power electronicization in power system, grid-forming converters with voltage source characteristics will become conventional equipment in modern power systems. In order to conduct accurate and efficient control and operation analysis for power systems equipped with grid-forming equipment and to study their safety and stability characteristics, it is necessary to reduce the complexity of grid-forming converter model with strong nonlinear characteristics. Conventional simplification methods based on current loops and voltage control loops neglect the potential effect of inner loop control and line coupling impedance on the synchronous stability of the equipment. Ensuring the accuracy of stability analysis can be challenging in certain scenarios. Therefore, based on the existing order reduction methods, fully considering the small-signal characteristics of inner loop control and the influence of line coupling impedance, a series of improved simplified models are proposed. Moreover, the adaptability of each simplified model to frequency domain, eigenvalues, and time domain analysis is discussed. It turns out that there is no simplified model that can always maintain high accuracy in all scenarios. It is concluded that the simplification method needs to be changed according to the scenario. According to the analysis results, the relevant basis for selecting the simplified model of the converter and adjusting the control parameters is summarized.