Porous, redox oxide-based, ceramic structures for efficient solar energy harvesting, transformation and storage

Kurzfassung

Concentrated Solar Power (CSP) systems are special mirror assemblies that track the sun and concentrate its radiation, converting thus solar energy to medium- to high-temperature heat and through that to electricity. CSP power plants that employ air as the heat transfer fluid can benefit from commonalities in materials and design requirements within the entire spectrum of solar energy harvesting chain, namely capture, transformation and storage-related processes. Such commonalities can be exploited with the synergistic use of the gas-solid heat exchange functionality of ceramic porous structures like honeycombs and foams and the thermochemical activity of redox pair oxides. Honeycombs or foams capable of absorbing concentrated solar irradiation and therefore operating as volumetric receivers in the solar energy capture module, when coated or made entirely of redox oxide systems that can react with water or carbon dioxide, can be employed as chemical reactors for the production of the so-called solar fuels like hydrogen and syngas. In this case, the harvested solar energy is not converted directly to electricity, but into chemical bonds (chemical substances). With a similar rationale, chemically inert porous solid materials operating as regenerative recuperators during off-sun operation of air-operated Solar Tower Power Plants, if coated with or manufactured of, other oxide systems, capable of redox operation within this temperature range accompanied by significant heat effects, can render the storage concept from “purely” sensible to “hybrid” sensible/ thermochemical one within the same volume. The construction modularity of such systems provides for the design of the entire reactor/heat exchanger module as a structure with rational spatial variation of redox oxide materials chemistry and solid materials porosity in three dimensions, tailored to the local temperature and flow conditions. The work presents an up-to-date summary of our work on such systems with emphasis on scaling-up of the technology.