With the rapid growth of renewable energy under the goals of carbon peaking and carbon neutrality, power systems face increasing demand for long-duration energy storage and flexible peak regulation. Electrically heated solid particle thermal energy storage (TES) is a promising option because it offers high operating temperature, wide storage temperature range, low-cost storage media, good thermal stability, clean electric-to-thermal conversion, and strong potential for integration with renewable energy systems and coal-fired power plants. This paper aims to clarify the research progress, major bottlenecks, and future directions of this technology.

This paper reviews electrically heated solid particle TES from the perspectives of heating principles, representative devices, application scenarios, and key scientific and engineering issues. Two major routes, resistance heating and induction heating, are discussed in detail. For resistance heating, both indirect and direct modes are considered. Indirect resistance heating transfers heat from electric heating elements to particles through conduction, convection, and radiation. It has advantages such as simple structure, mature equipment, and good controllability, but it also suffers from additional thermal resistance and heat loss. Direct resistance heating allows conductive particles or conductive particle networks to generate Joule heat directly, which improves heating compactness and electric-to-thermal efficiency, while also introducing challenges related to conductivity stability, local overheating, oxidation resistance, and the formation of reliable conductive paths. Induction heating provides non-contact heating and rapid thermal response, and is attractive for high-temperature applications. However, its performance depends strongly on frequency, magnetic field intensity, coil design, particle size, electrical conductivity, magnetic permeability, and temperature-dependent material properties. In addition, induction heating systems often face higher equipment cost, cooling demand, and lower overall efficiency in practical applications. Representative devices for solid particle heating, including tubular heaters, plate heaters, fluidized-bed heaters, and moving-bed heaters, are also summarized. Tubular and plate heaters are relatively mature and suitable for small- and medium-scale systems, whereas fluidized-bed and moving-bed configurations show better heat transfer performance and greater potential for high-power and continuous operation. At the same time, they involve more complex issues such as particle flow stability, pressure drop, abrasion, temperature uniformity, and model accuracy. This paper further discusses key challenges, including high-temperature particle flow and heat transfer mechanisms, optimization of electric heating efficiency, durability of particle materials under thermal cycling, cost control, and coordinated operation with coal-fired power plants.

Electrically heated solid particle TES is a promising technical route for renewable energy integration, long-duration energy storage, and flexible operation of coal-fired power plants. Resistance heating is currently more mature and economically competitive, while induction heating has advantages in non-contact heating, rapid response, and high-temperature adaptability, but still requires progress in efficiency improvement, cost reduction, and particle material matching. Future research should focus on multi-field coupled particle flow and heat transfer, low-cost and high-performance particle materials, modular electric heating devices, heat loss control, and coordinated control strategies, so as to promote the scale-up, industrialization, and commercialization of this technology.