1. Introduction Higher efficiency powercyclesarebeingpursuedtoreduce the levelizedcostofenergyfromconcentratingsolarpower towertechnologies [1]. Thesecycles,whichincludeair-Brayton, supercritical-CO2 (sCO2) Brayton,andultra-supercriticalsteam cycles,requirehighertemperaturesthanthosepreviouslyachieved using centralreceivers.Currentcentralreceivertechnologiesemploy eitherwater/steamormoltennitratesaltastheheat-transferand/or working fluid insubcriticalRankinepowercycles.Thegrossthermal- to-electricefficiencyofthesecyclesincurrentlyoperatingpower- towerplantsistypicallybetween30and40%atinlettemperatures Contents listsavailableat ScienceDirect journal homepage