Slag as an Inventory Material for Heat Storage in a Concentrated Solar Tower Power Plant: Experimental Studies on Design and Performance of the Thermal Energy Storage

Thermal energy storage systems are essential for concentrated solar power plants to guarantee continuous energy output. Currently used molten salt technologies are very expensive and demand continues technical attention. An option for cost reduction and efficiency increase is to use regenerator-type energy storages. Further cost reduction can be achieved by using the waste metallurgical slag from electric arc furnace as an inventory material for the thermal energy storage. So far only a few studies have been carried out regarding the use of EAF slag as TES inventory material. Nonetheless, there are still fundamental questions about this low-cost material and storage design to be clarified. The European project REslag deals with those questions. In this paper, experimental design and performance studies of slag-based thermal energy storage are carried out. The basic methodology for simulation model set up is declared and a lead design is identified. The set-up of the used test facility, called HOTREG, is described and the measurement arrangement is explained in detail. Furthermore, experimental results of the thermal behavior of the HOTREG with slag as heat storage inventory are presented and compared with results of an appropriate simulation model. Here, the comparison yielded an agreement of over 90 %.