(449b) Metal Oxide Redox Materials for Solar Thermochemical Energy Storage

Thermochemical energy storage (TCES) systems are of great interest in concentrated solar power (CSP) applications. Storing sunlight as chemical energy during the day can enable power generation at night or during cloudy periods, effectively alleviating the inherent intermittency of solar sourced electricity. Metal oxides are among the most attractive TCES materials because they possess high-energy density and high reduction/oxidation temperatures (>800°C) suitable for driving high-efficiency thermodynamic power cycles. However, limitations involving high-temperature heat transfer, particle handling, sintering, and chemical performance of the metal oxide materials are still problematic in practical application.

Past works generally focus on evaluating pure metal oxide systems and investigate a select few mixed metal oxide systems in detail. In this work, we pre-selected over 100 high-potential mixed-metal oxide systems based on a comprehensive literature survey and then screened those materials for suitability in redox based high-temperature TCES using thermodynamic database software. The potential candidates were down-selected to the most promising contenders based on several selection criteria: high-temperature stability, large redox reaction enthalpy, and reaction temperatures of approximately 700-1100 °C for CSP applications. Ongoing and future work we will focus on experimental testing of the identified compositions to identify actual redox behaviours and to evaluate other thermochemical criteria—appropriate cycling physical stability, maintained chemical activity over many redox cycles, and acceptably fast reaction kinetics.