Thermal energy storage is a key technology for global energy sustainability. It plays a vital role in renewable energy application and waste heat recovery by adjusting the time-discrepancy, space-discrepancy and instability between energy supply and energy demand. A promising multifunctional solid-gas thermochemical sorption heat transformer is proposed in this paper for integrated energy storage and energy upgrade, combined cooling and heating supply, and recovering waste heat. Thermal energy is stored in form of chemical potential resulting from thermochemical sorption process of solid-gas working pair. The operating principle and working performance of the proposed thermochemical sorption heat transformer is analyzed and compared at different operating conditions. Thermodynamic analysis showed that the advanced thermochemical sorption heat transformer has multipurpose energy application for integrated energy storage as well as energy upgrade, combined cooling and heating supply, and waste heat recovery. Moreover, it has a distinct advantage of 10 times energy density higher than conventional sensible heat and latent heat storage methods. This makes it a very promising compact high energy density heat storage method for integrated energy storage and energy upgrade. The presented energy storage technology can promote the application of thermal energy storage and waste heat recovery in large-scale industrial processes as well as the use of renewable energy sources. (C) 2014 Elsevier Ltd. All rights reserved.