THIS PROJECT SEEKS TO TEST A NOVEL DUAL-MEDIA THERMAL ENERGY STORAGE (DMTES) FOR CONCENTRATING SOLAR THERMAL APPLICATIONS (CST). THE STORAGE SYSTEM IS A THERMOCLINE, WHICH IS APPROXIMATELY BOTH A SOLID ROCK-LIKE MATERIAL AND A TANK HEAT TRANSFER FLUID (THTF). A LOW-COST SOLID WITH FAVORABLE COST AND MATERIAL CHARACTERISTICS WILL BE CHOSEN. THE STATE-OF-THE-ART FOR CONVENTIONAL THERMAL ENERGY STORAGE IS A TWO-TANK STORAGE SYSTEM WITH OPPORTUNITIES FOR IMPROVING COSTS LIMITED TO LOW-COST TANK AND STORAGE MATERIALS. A SINGLE-TANK THERMOCLINE SYSTEM, SUCH AS DMTES, CAN REDUCE COSTS BY REDUCING THE VOLUME REQUIRED OF TANK AND STORAGE MATERIAL.