Characterization of Several Moroccan Rocks Used as Filler Material for Thermal Energy Storage in CSP Power Plants

This paper demonstrates the potential of the quartzite as an economic and efficient filler material in thermal oil direct thermocline storage system. This natural rock appears as a good candidate for thermal energy storage by sensible heat up to 350 °C.In the present study, many experiences were conducted in order to choose the best rock among five varieties (quartzite, basalt, granite, hornfels and marble) which are found abundant in Morocco. The optimal rock was selected according to various criteria such as surface characteristics, porosity, density, calorific capacity, hardness, mechanical resistance. The chosen rock should also provide a thermal stability during energy exchange with the heat transfer fluid (HTF). It should be noted that choice of the rocks as a filler material may reduce the quantity of the HTF used for charging and discharging the thermal energy. Hence, the shrinkage of tank volume by thermocline sensible heat storage system using rocks as filler materials allows reducing the cost with an increase in the efficiency of the system.