High Temperature Sensible Storage-Molten Salts

Abstract

The technological limitation in the use of solar energy is intermittent generation due to the lack of storage capacity. The impediment that plants do not generate at night and cloudy days makes their massive participation in the energy matrix complex. For this reason, storage systems allow solar thermal power plants a more stable generation of electrical energy independent of the variability of the solar resource. These systems increase the performance and competitiveness of CSP technologies in terms of LCOE (Levelized Cost of Energy) (Stepper, 2014). The main types of thermal energy storage are classified into thermochemical storage, latent heat storage, and sensible heat storage. In the first case, this type of storage involves a reversible chemical reaction where the used medium must have the ability to completely dissociate in the temperature range of the solar field heat. The amount of heat stored will depend on the heat of reaction and the degree of conversion that is achieved in the exothermic and endothermic process. In the case of latent heat storage, the materials used undergo a phase change at a temperature within the upper and lower range of the solar field. The typical phase used is solid-liquid. These systems are governed by the specific heat of the material and by the enthalpy of the phase change, which allows a large amount of energy to be stored in a smaller volume, and thus at a lower cost if compared to sensible heat storage systems (González-Roubaud et al., 2017).