This proposal outlines the motivation for the design and fabrication of a solar thermogravimetric system (Solar-TG) necessary for investigating the kinetics of high-temperature endothermic reactions driven by concentrated solar radiation. The need for a Solar-TG stems from fundamental research in solar thermochemistry being performed by the Professorship of Renewable Carriers (PRE) at ETH Zurich, in close collaboration with PSI’s Solar Technology Laboratory. The R&D projects are directed towards the efficient production of solar fuels and materials. Examples are thermochemical cycles based on metal oxides redox reactions for splitting H2O and CO2, the carbothermal reduction of metal oxides for extracting metals (e.g. Al, Si), and the gasification of carbonaceous materials for producing syngas and liquid fuels.
A major challenge in the solar reactor design and optimization for maximum solar-to-fuel energy conversion efficiency is matching the radiative heat transfer to the chemical reaction kinetics. For accomplishing that, it is important to acquire fundamental understanding of the reaction mechanisms and determine overall kinetic rate laws under the similar heat and mass transfer characteristics existing in highly concentrating solar systems, such as solar towers and solar parabolic dishes. The proposed Solar-TG should deliver the information needed by allowing temporal monitoring of the reaction with reactants directly exposed to concentrated solar radiation. Temperatures up to 3000 K and heating rates exceeding 1000 K/second can be achieved with solar concentration ratios equivalent to 5000 suns. The Solar-TG offers the additional advantage of being able to operate at vacuum pressures. Coupled with gas chromatography, mass spectrometry, and pyrometric temperature measurements, the mechanisms of high-temperature solar thermochemical processes can be examined in-depth. The significance of this research lies in the advancement of the thermo-sciences and engineering directed at developing solar chemical technologies, which in turn have the potential of making significant contributions to sustainable, clean, and efficient energy utilization.