(498e) Grid-Scale Thermochemical Energy Storage Using Mixed Metal Oxide Redox Cycles

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 (>1000°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.

A novel, grid-scale CSP/TCES system design that addresses many of the traditional problems associated with metal oxide TCES has been developed at the ANU. This presentation serves as a broad overview of recent work surrounding the designed CSP process, including improvements to the metal oxide active materials, solar reactor design, optical field development, and preliminary techno-economic analyses. Improved chemical performance of the active material is being explored through metal co-doping and the intentional formation of solid solutions. The incorporation of fluidized bed reactors for solar reduction and off-sun oxidation allows for improved heat transfer and enhanced chemical kinetics, and also enables high temperature pneumatic transport of gas-solid reacting flows. The initial solar reactor concept consists of one or several vertical fluidized bed reaction tubes in a beam-up solar cavity receiver, which allows for well-controlled fluidization, high optical efficiency, and minimized convective heat losses. The techno-economic analysis of a 100 MW_Th grid-scale facility is employed to predict the levelized cost of electricity.