Solar Thermochemical Energy Storage Through Carbonation Cycles of SrCO₃/SrO Supported on SrZrO₃

Solar thermochemical energy storage has enormous potential for enabling cost-effective concentrated solar power (CSP). A thermochemical storage system based on a SrO/SrCO₃ carbonation cycle offers the ability to store and release high temperature (≈1200 °C) heat. The energy density of SrCO₃/SrO systems supported by zirconia-based sintering inhibitors was investigated for 15 cycles of exothermic carbonation at 1150 °C followed by decomposition at 1235 °C. A sample with 40 wt % of SrO supported by yttria-stabilized zirconia (YSZ) shows good energy storage stability at 1450 MJ m^-3 over fifteen cycles at the same cycling temperatures. After further testing over 45 cycles, a decrease in energy storage capacity to 1260 MJ m^-3 is observed during the final cycle. The decrease is due to slowing carbonation kinetics, and the original value of energy density may be obtained by lengthening the carbonation steps.