Massive integration of renewable energy requires large-scale energy storage capacities. However, only a limited number of commercial technologies are available, and some barriers exist to fully covering the market with their characteristics. A huge R&D effort is being made to develop new sustainable energy storage technologies. Among them, thermochemical energy storage systems are highly interesting because of their potential high energy densities, high delivery temperatures and seasonal storage capacity. They will depend on the reactions and components involved in the system. Carnot batteries are also of high interest for efficiently integrating renewable electricity under different applications and temperatures. The author analyses recent technological advances and trends for Carnot Batteries and Thermochemical Energy Storage systems in this work. Relevant results from recent European Union-funded projects based on Calcium Looping and Transcritical Carbon Dioxide are presented and discussed.