Round Robin Test on Enthalpies of Redox Materials for Thermochemical Heat Storage

Among systems proposed as suitable for thermochemical heat storage (TCS), redox oxides merit significant attention for high temperature applications in Concentrating Solar Power (CSP) plants. The specific enthalpy of the reaction is a key parameter to establish the storage capacity of the system. Consequently, there is considerable practical interest in accurately determining this parameter. Discrepancies in the referenced enthalpies may arise from inadequate protocols and/or sets-ups for measuring thermodynamic properties at high temperatures, or the presence of impurities in the samples. This work presents a round robin test conducted by eight institutions, research centers and companies during 2015-2016 in order to develop a standard procedure for the measurement of enthalpies in the relevant thermochemical processes at high temperature. The initiative was organized within the Working Group on Thermal Storage (Activity on "Materials for Thermal Storage") in SolarPACES Task III.