CHESTER: Experimental prototype of a compressed heat energy storage and management system for energy from renewable sources

The increasing share of renewable energies in the electricity grid requires storage technologies to balance energy supply and demand. Thermally integrated pumped thermal energy storage systems are considered a promising technology for medium to large-scale storage applications. Among these, compressed thermal energy storage in particular has been identified in numerous theoretical studies as a promising candidate. Despite these studies, the feasibility of the thus far theoretical concept has not yet been proven experimentally. To overcome this gap this publication presents for the first time the entire setup and experimental results of the world's first CHESTER (Compressed Heat Energy Storage for Energy from Renewable Sources) laboratory prototype at a representative scale consisting of a high-temperature heat pump and an organic Rankine cycle coupled by a combination of a sensible and a novel dual-tube latent heat storage as a high-temperature thermal energy storage system. The stable operation of a fully integrated CHEST system on a 10 kW scale was demonstrated and the stable function of the latent heat storage unit as both a condenser and an evaporator was confirmed. With the current prototype, which combines three first of its kind subsystems, efficiencies of up to 37 % have been achieved. The presented results confirm the practical feasibility of the thus far theoretical concept and provide guidance for further optimization of the components and more importantly the interaction between the individual subsystems.