Selection of materials for high temperature sensible energy storage

Availability of thermal energy storage systems (TES) is a key to ensuring continuous power supply from solar thermal power plants. The application of sensible heat storage (SHS) in solid media is an attractive economic option, but is dependent on identifying suitable SHS media. Given the growing number of new materials available today, finding a suitable material is a time-consuming and difficult process. This paper demonstrates the use of a materials selection software package and identifies suitable SHS materials for high temperature (> 500 degrees C) TES systems. The environmental performance of some selected materials was also evaluated using the package. Common materials such as alumina, silicon carbide, high temperature concrete, graphite, cast iron and steel were found to be highly suitable for SHS for the duty considered (500-750 degrees C). For cost comparison, a simple heat exchanger, consisting of a packed bed of the materials (in brick or block form) heated by an inert gas, was considered. On the basis of equivalent gas phase heat transfer, high alumina cement concrete blocks had the lowest cost, followed by a common refractory brick at <US$ 10/kWh (thermal). High temperature concretes, such as the high alumina cement-based materials and alumina-silicate geoploymers, were identified as having potential for SHS media as they are cheap composite materials. Their thermo-physical properties could be optimised for SHS by a suitable choice of aggregates, binders and additives. (C) 2013 Elsevier B.V. All rights reserved.