In view of the electricity demand of users and the power generation of renewable energy, an optimal scheduling model of grid-connected wind-optical-battery-waste mine pumped storage combined power generation system is established, with the optimization objective of minimizing the total operating cost of the system. Moreover, the results of the optimal scheduling are measured with the evaluation indexes of the equivalent load variance, the fluctuation rate of the contact line, and the power supply loss rate. The optimal solution is performed using CPLEX solver for the scheduling model. Through simulation on the optimal scheduling models of three different energy storage forms, it is concluded that the total cost of the hybrid energy storage in the form of storage battery and abandoned mine pumped storage reduces by 62.21% and 49.18% compared with that of the battery alone and abandoned mine pumped storage alone, respectively. The optimization results are ranked and evaluated by using the combined entropy weight rank sum ratio method, and the weighted rank-sum ratio of the wind-solar-battery-abandoned mine pumped storage combined power generation system is 0.833, with the highest score ranking. The results show that the proposed model not only improves the operation economy of the system, but also enhances the reliability of the system power supply, which verifies the rationality and effectiveness of the proposed model.

Compressed air energy storage (CAES) technologies have garnered widespread attention due to their large scale, high efficiency, and environmental friendliness. Among them, the non-combustion compressed air energy storage technology is mature, and produces no carbon emissions during operation. There are already several adiabatic non-combustion compressed air energy storage power stations in operation, under construction, and in planning in China. However, the design parameters of the CAES system lack a unified standardization system, which poses many challenges in system design and performance optimization of CAES. To solve this problem, the design of medium-temperature and high-temperature thermal energy storage system schemes for a 200 MW class CAES system is presented, the key equipment parameters and system boundary conditions are determined. Moreover, the performance and technical economy of the medium- and high-temperature thermal energy storage system schemes is compared. The results show that, the high-temperature thermal energy storage system is superior to the medium-temperature thermal energy storage system in performance indicators, but it has a higher investment cost, indicating that when choosing the thermal energy storage technology route for large-capacity CAES systems, it is necessary to consider comprehensively based on specific application scenarios and economic budgets.

Decarbonization in thermal power industry is directly related to the realization of the “double carbon” target, while the circulating fluidized bed boiler has the advantages of wide fuel applicability and can carry out large-scale fuel blending. Biomass fuel is a renewable “zero-carbon” energy source, its blending can greatly reduce the carbon emissions of thermal power plants. Based on the existing circulating fluidized bed boilers and coal-fired conditions, biomass co-firing tests were conducted, and comprehensively evaluation was also carried out on combustion stability, pollutant emissions, and thermal efficiency. The co-firing experiments results showed that, as the co-firing ratio increased, the coal consumption rate per unit of steam production significantly decreased, with stable combustion conditions maintained throughout the process. Under co-firing conditions, the consumption of limestone decreased to approximately 4.5 kg for 1 ton steam production, with SO₂ emissions meeting the standards. Blending raised the furnace temperature, elevated the exhaust temperature, increased the fly ash content, and slightly increased the heat loss. Through regulating the air volume ratio, material layer pressure difference and excess air coefficient, the overall thermal efficiency closely approached the design value. Under long-term operating conditions, the blending ratio of biomass reached about 30%, and the emissions of SO₂ and NO_x were qualified. The tail heat exchanger was not corroded obviously, and the CO₂ emission reduction amount reached about 480 kg for 1 ton steam production.

To improve the control effect of key parameters and energy conversion efficiency of ultra-supercritical coal-fired power generation units during load cycling process, 600 MW class ultra-supercritical coal-fired power generation units are taken as the research objects to carry out modeling and verification. The deviation of key thermal parameters meets the specified range of thermal power simulation standard. The spatiotemporal distribution model of internal heat storage in thermal system of coal-fired power generation units is established, and the water-fuel ratio and flue gas damper opening control logic of the feedforward internal heat storage state of the unit are proposed. The real-time heat storage state of the unit during the load cycling process is fed forward to the flow rate of feed water, coal, and flue gas damper control. The simulation results show that, when the unit load cycling rate varies from 1.0% Pe/min to 3.0%Pe/min within 40%~70% THA load range, the absolute value of the cumulative main steam temperature deviation rate decreases by 27%~31%. The average power generation standard coal consumption rate of the unit decreases by 0.37~0.65 g/(kW·h) during the transient process. The proposed control strategies improve the control accuracy of key thermal parameters and the energy conversion efficiencies of the ultra-supercritical coal-fired power generation units during load cycling transient processes.

With the rapid advancement of renewable energy power generation, thermal power units need to take on major peaking tasks. Molten salt thermal storage technology, as a prominent method for thermal power peaking, can effectively improve peaking performance of the units. The Ebsilon software is employed to model a subcritical 300 MW unit integrated with coupled molten salt thermal storage system. Considering the operational conditions of supplying industrial steam to external entities, several indexes such as the storage/exothermic thermal efficiency, load variation and thermoelectric conversion rate of three heat storage/exothermic schemes are investigated comparatively. The results indicates that, during the heat storage process, the heat storage scheme 3 (the heat source for heat storage is the main steam, reheat steam and medium-pressure cylinder exhaust, and the exothermic medium-pressure cylinder exhaust goes directly to the condenser) exhibits the highest load variation, reaching up to 102.63 MW. Meanwhile, the heat storage scheme 1 (employing main steam and reheat steam as the heat source for storage) demonstrates the superior thermal efficiency at 28.76%. During the discharge process, exothermic scheme 2 (heat from high-temperature molten salt is used to supply industrial steam and preheat condensate) has the largest load variation, release thermal efficiency, and thermoelectricity conversion rate, which are 34.69 MW, 46.14%, and 59.07%, respectively. This study can provide theoretical guidance for the study of peak performance and thermal economy of thermal power units coupled with molten salt thermal storage system.

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.

With the increasing penetration rate of renewable energy in China’s power system in the future, the stability of the system will face more severe challenges. Long-term energy storage technology plays an important role in balancing grid demand, improving grid stability, promoting the consumption of renewable energy, and promoting green and low-carbon development in the power system. Long-term energy storage has a wide range of application scenarios on the power supply side, grid side, and load side of the system, which is of great significance for the development of China’s new power system. Firstly, the characteristics and development trends of the current new power system are introduced, and the supporting role of long-term energy storage technology in the new power system is analyzed. Then, the technical principles and routes of five long-term energy storage technologies, such as the compressed air energy storage, lithium-ion battery energy storage, liquid flow battery energy storage, molten salt energy storage, and hydrogen energy storage, are summarized. The advantages and disadvantages of various long-term energy storage technologies are also analyzed. Finally, the future application prospects of long-term energy storage technology in the new power system are discussed.

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.

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.

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.