Advances in ice thermal energy storage for low-carbon and flexible cooling systems

This review synthesizes recent advances in ice thermal energy storage (ITES) for low-carbon and flexible cooling, with emphasis on system typologies, building applications, photovoltaic (PV) coupling, intelligent control, and future deployment pathways. The review compares the main ITES configurations, including ice-on-coil, encapsulated ice, ice slurry, and emerging hybrid concepts such as ejector-type slurry generation, microchannel plates, and foam-enhanced structures. Conventional coil-based and encapsulated systems typically provide 35-65 kWh/m 3 , whereas slurry-based systems can reach 70-90 kWh/m 3 , while heat-transfer enhancement measures can accelerate freezing and melting by roughly 15-40 %. Across building applications, ITES commonly reduces peak cooling demand by 20-40 % and operating costs by 10-30 % relative to conventional direct cooling, with higher savings reported under strong demand charges. Compared with battery-plus-electric-cooling strategies, ITES is less versatile but can store cooling directly and relieve air-conditioning peaks more effectively in cooling-dominated buildings. The review also shows that economic viability depends on tariff structure, capital recovery, and utilization rather than operating savings alone. Recent progress in model predictive control, AI-assisted forecasting, and hybrid optimization has improved scheduling, renewable utilization, and operational robustness, while PV coupling increases on-site self-consumption and reduces evening grid imports. Key barriers remain in uneven phase-change dynamics, integration complexity, limited monitoring, lack of standardized modular products, and insufficient lifecycle evidence. Future work should strengthen long-term field validation, environmental assessment, techno-economic comparison with competing storage pathways, and scalable coordination from buildings to district and multi-energy systems.