SUMMARY

Sunlight is an abundant energy resource but is relatively dilute and intermittent. These challenges may be overcome in regions with plentiful solar resources by using concentrated solar irradiation to generate high temperature process heat to produce electricity from a power cycle (i.e., concentrated solar power). Concentrated solar power economic competitiveness can be greatly improved upon by incorporating chemical and sensible energy storage, significantly extending solar electricity production to periods when sunlight is unavailable and electricity is in peak demand. A two-step metal oxide solar thermochemical cycle is proposed to achieve chemical and sensible energy storage of sunlight for on-demand electricity production and encompasses: 1) the sensible heating and endothermic thermal reduction of metal oxides using concentrated solar irradiation, and 2) the extraction of stored sensible and chemical energy during the exothermic oxidation and delivery of process heat to an air-Brayton cycle. Realization of the cycle requires optimization of a solar thermochemical reactor to achieve efficient solar energy storage.
This study will focus on the design, modeling, and construction of a laboratory-scale solar thermochemical reactor to promote significant reduction and high temperatures within a dense, granular flow of metal oxide particles. The binary metal oxide pair Co3O4/CoO and the perovskite type metal oxide CaAl0.2Mn0.8O3-δ have been identified as promising thermochemical energy storage media. This reactor will be developed using, 1) thermodynamic and kinetics studies of viable metal oxides, 2) extensive mass and heat transfer modeling of the solar thermochemical reactor, and 3) the design, construction, and testing of a laboratory-scale reactor. Upon completion of this project a scalable, solar technology will be developed which may be integrated with pre-existing concentrating solar and air-Brayton infrastructures to promote rapid inclusion of energy storage in concentrated solar power facilities.