Development of a compressed heat energy storage system prototype

Compressed Heat Energy Storage (CHEST) systems are a specific variant of Pumped Thermal Energy Storage systems (PTES) based on the Rankine cycle. The CHEST system described in this work consists of a high-temperature heat pump, a high-temperature thermal energy storage system combining both latent and sensible heat storages, and an organic Rankine cycle system. The use of working fluids with a low global warming potential and zero ozone depleting potential are also considered. In this paper the design and operation modes of a CHEST system concept are presented. A numerical model was developed in TRNSYS software, which served to analyse the system´s capabilities not only as a promising power-to-heat-to-power system able to achieve high electrical roundtrip efficiencies, but also as a highly flexible energy storing system when coupled to a Smart District Heating (DH) installation. Finally, recommendations for the definition of an experimental set-up for the validation of the CHEST concept are provided.