Low Temperature Molten Salts in Sustainable Energy Production

Power production is moving towards more renewable energy sources with the aim of reducing CO2 emissions. Examples of emerging technologies to meet this need include: concentrated solar power plants and liquid air energy storage systems. The overall system efficiency of such technologies can be increased by the introduction of a thermal energy storage system, to host excess heat and eventually to release it when needed. This work was focused on the identification of new molten salt mixtures as the thermal medium to act as both thermal energy storage and heat transfer fluid. Firstly, the thermo-physical properties of the commercial salt mixtures were reproduced using Aspen + , resulting in 5 nitrate-based mixtures providing the suitable trade-off between melting point temperatures and volumetric heat capacities. Secondly, 13 new salt compositions with improved volumetric heat capacities were created utilising the same constituents as the baseline mixtures, and then experimentally tested for the identification of the melting point. As a result, 4 alternative new molten salt mixtures, including 2 from the CaLiNaK family, were identified as preferred candidates due to higher improvements in volumetric heat capacity (15-19%) and only moderate increase in melting point temperature (20-30°C) with respect to the baseline mixture.