SOLAR THERMOCHEMICAL HYDROGEN GENERATION WITH A 250-KW STRUCTURED REACTOR: EXPERIENCES FROM TESTS AT THE JÜLICH SOLAR TOWER

Abstract

Thermochemical water splitting using two-stage REDOX processes and concentrated solar radiation as an energy source has been the focus of process engineering research for more than two decades. It is considered as a promising technology for producing green hydrogen and liquid green fuels based on it at competitive prices in the medium term. In this process concentrated solar radiation is directly converted into storable chemical energy. The present article reports the results of an experimental campaign, which has been carried out at the research level of the Solar Tower Jülich to further demonstrate the feasibility of this technology. Based on the experience from prior tests at a large-scale solar simulator a combined receiver/reactor has been re-designed and built up. The reactor was operated at temperatures between 1400°C and 1000°C using radiative power of up to 600kW generated by part of the heliostat field of the Solar Tower. As redox materials open porous ceria coated zirconia foams have been used. It could be shown that the production of hydrogen in a medium scale structured reactor is possible. The tests also revealed which improvements concerning structure, optical and thermal management as well as operational parameters are necessary to achieve satisfying efficiencies.