[Display omitted] • An innovative amine-based thermal energy storage (ATES) technology was developed. • ATES system utilize 84% of CO 2 reaction enthalpy for heat output. • The system obtained high-grade heat at ∼130 °C and energy density of 210 kJ/kg. • System energy efficiency of 70% was obtained via regeneration energy improvement. Thermal energy storage (TES) bridges the intermittence of renewable energy to generate steady and efficient clean energy. While amine-based CO 2 capture is a leading technology for CO 2 emission reduction, we innovatively employed the amine technology for long-term thermal energy storage, namely amine-based TES (ATES). The system utilises the thermally reversible amine-CO 2 reaction as the energy storage working pair, where low-grade thermal energy is used to break the amine-CO 2 chemical bond with the heat stored and released via exothermic amine-CO 2 reaction to produce high-quality thermal energy when required. Using benchmark absorbent monoethanolamine (MEA), we simulate and optimize the ATES system, and demonstrate that ATES exhibits desirable thermal energy storage performance with high-quality heat output up to 131 °C, high thermal energy conversion efficiency of >70%, moderate energy density of 210 kJ/kg and long-term storage, which outperforms the water-based sensible thermal storage technology. More importantly, the ATES is built on commercially viable amine process and heat exchange system, indicating its great potential for commercial applications, such as space heating and industrial waste heat storage. [ABSTRACT FROM AUTHOR]