Identification of suitable storage materials for solar thermal power plant using selection methodology

Due to the intermittent nature of solar energy, there is a need to store heat to meet the needs when solar light is not available. Rock bed using air as heat transfer fluid (HTF) is being now used for thermal energy storage (TES) in concentrated solar power (CSP) plants. It is considered as a cost effective storage system. However, no detailed works have been published on selection and identification of rocks for high temperature storage applications. The scope of the present study is to choose the most suitable rocks for high temperature sensible heat storage (SHS) using a methodology based on laboratory measurements. Thus, experimental characterization of several rock types has been performed. An experimental device has been made for thermal conductivity measurement at room temperature. The obtained results show that the gabbro rock is the best candidate material for CSP plants. Comparative study with some other conventional materials found in literature indicates that rock is an efficient filler material for high temperature TES. From the obtained results and correlations, a second selection methodology has been proposed in order to minimize the steps of selection using simple and few tests.