Thermal Energy Storage Technologies: A Review of Current Landscape and Future Directions

Thermal Energy Storage (TES) is a critical technology for enhancing the reliability, flexibility, and efficiency of renewable energy systems. This review paper provides an inclusive study of TES mechanisms like sensible heat storage (SHS), latent heat storage (LHS), thermochemical energy storage (TCES), and hybrid systems, and emphasizing their operating principle, material property, and application context. Key performance indicators are systematically assessed: SHS (50–150 kJ/kg, 70–90% efficiency), LHS (150–250 kJ/kg, 75–95% efficiency), and TCES (250–1200 kJ/kg, 75–90% efficiency), alongside thermal conductivity ranges (0.2–10 W/m.K) and environmental impacts. A unified temperature classification is applied across technologies: low (600 °C), ensuring consistency in comparative analysis. This paper shows thermal energy storage options by incorporating nano-enhanced phase change materials, reversible thermochemical reactions for seasonal storage, and innovative system designs that improve operational responsiveness and grid integration. Despite substantial advancements in thermal energy storage technologies, several critical challenges continue to hinder their widespread adoption and long-term reliability. Issues of material durability, economic feasibility, and large-scale deployment remain unresolved, especially for high-temperature and long-duration storage applications. Addressing these limitations is essential to unlock the full potential of TES in supporting sustainable energy systems. This paper reviews that to emphasize individual storage mechanisms, synthesizes technological progress, deployment insights, and regional relevance to establish a framework for selecting and advancing TES solutions that support low-carbon energy transitions, industrial decarbonization, and climate-resilient infrastructure.