The main progress in the first 18 months of a four-year project has been in preparing and upgrading the experimentation infrastructure and in designing and fabricating a novel reactant structure and reactor with the potential of more than 3-fold efficiency improvement compared to the preceding project. Specifically, the main progress has been in the development of
1) a high-flux solar concentrating subsystem, including the development of novel tools and equipment for focus characterization, control, and optimization,
2) a solar thermochemical reactor subsystem, including the development of novel structured redox material and the design of an integrated heat recovery system
3) a gas-to-liquid conversion subsystem, including the development of a hydrotreating system for converting heavy hydrocarbon products to liquids in the kerosene range,
which in the next 18 months will be integrated in the solar research plant at IME Energía in Móstoles, Spain. Furthermore, for the pathway towards commercial deployment
4) a system-level analysis and development roadmap is performed.
More specifically, the work performed and main achievements are:
Ad 1) Extensive campaigns of characterization of the heliostat field in terms of optical quality and pointing accuracy have been performed for best beam delivery to the small size of the reactor aperture. A pointing error between 1-3 mrad has been achieved. A new flux measurement system has been developed and pre-tested. Its validation at the solar tower is postponed until the setup with new calorimeter is installed onsite by the end of 2025.
Ad 2) For the development of novel structured redox material a heat and mass transfer model has been completed. The design and fabrication of these novel structures has been successfully achieved for testing in the smaller-scale 5-kW solar reactor. As a result, the most performant structures can be determined by numerical models and ceria-based hierarchical porous structures can be properly fabricated by additive manufacturing, even from recycled ceria materials which confirms the viability of recycling for the resource-efficient use of ceria.
The conceptual development and modeling of a heat recovery system has been completed while progressing with the engineering of a 50-kW solar reactor with integrated heat recovery. The model of a dual heat storage configuration achieves recuperation effectiveness of approximately 31% which enables the achievement of the overall target solar-to-fuel efficiencies. The engineering work has implemented critical design solutions, based on the modeling results and on commercially available components where feasible.
Ad 3) An existing gas-to-liquid (GtL) system has been successfully adapted to accommodate larger gas streams. The factory acceptance test of the GtL system and the catalytic cracking reactor, developed for the upgrading step to produce kerosene, will be completed by the time of publication of this summary.
Ad 4) A process model for the complete fuel path has been developed for optimization and a systemic constraint analysis has been started. To this end, technologies and integration strategies with waste heat recycling for direct air capture (DAC) in arid regions were investigated. Furthermore, supply chains and recycling strategies for ceria-based catalyst materials were analysed, with an additional focus on 3D printing techniques in this context.
