SUNlight-to-LIQUID - Efficient solar thermochemical synthesis of liquid hydrocarbon fuels using tailored porous-structured materials and heat recuperation

Project Information

SUN-to-LIQUID II

Grant agreement ID: 101122206

DOI

10.3030/101122206

EC signature date 30 August 2023

Start date 1 November 2023

End date 31 October 2027

Funded under

• Climate, Energy and Mobility

Total cost

No data

EU contribution

€ 4 880 120,40

Coordinated by

BAUHAUS LUFTFAHRT EV
Germany

Periodic Reporting for period 1 - SUN-to-LIQUID II (SUNlight-to-LIQUID - Efficient solar thermochemical synthesis of liquid hydrocarbon fuels using tailored porous-structured materials and heat recuperation)

Reporting period: 2023-11-01 to 2025-04-30

Summary of the context and overall objectives of the project

Two particularly important targets in the global and European agendas are, respectively, (i) the Paris Agreement, concerning the limitation of global warming to 1.5°C, and (ii) the European Commission (EC) aims to eliminate net greenhouse gas (GHG) emissions on the path to climate neutrality by mid-century. Two key challenges of the transportation sector towards achieving this target in the transition to a society living on 100% renewable energy relate to an increased feedstock basis for renewable fuel production and to the long-term development of sustainable fuel technologies.
While electrification, and likely also hydrogen, will play a major role in the decarbonization of transportation, there will still be a continued need for energy-dense liquid hydrocarbon fuels, especially for aviation and shipping. Scalable technologies of renewable fuels from non-biological origin (RFNBO) will be required to meet the longer-term fuel demand.
SUN-to-LIQUID II develops a set of versatile technologies for solar fuel production from water and CO2, such as:
• an improved high-flux solar concentration system for applications using high-temperature process heat;
• efficient “solar-thermochemical” fuel production, i.e. a sunlight-driven high-temperature chemical conversion process, using novel 3D-printed materials in the solar reactor for the reduction-oxidation processes;
• heat exchange and recovery concepts to further improve the efficiency of high-temperature conversion processes.
The ultimate output will be a step-change technology advancement and a roadmap for a robust and sustainable conversion pathway to produce high-quality renewable liquid hydrocarbon fuel from the inexhaustible potential of solar energy.
The scale and significance of the project's expected social, economic and environmental impacts are obvious considering the fact that the SUN-to-LIQUID II technology has the potential to meet the future global renewable fuel demand with less than 1% of the arid land and with a potential for more than 80% greenhouse gas emission reduction. Therefore, it may have a profound impact not only on the long-term energy supply security worldwide but also in minimizing the carbon footprint of e.g. aviation and on the positive socio-economic development of economically challenged regions with arid climate, high levels of solar radiation & non-arable land.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

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.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The progress beyond the state of the art in the first 18 months of the project is partly represented by progress in the items (1) and (2) above.
Ad 1) The solar concentrator assembly will achieve average flux intensities beyond 2000 suns at the reactor’s aperture, exceeding solar concentration ratios typically obtained in Concentrated Solar Power (CSP) plants for electricity generation.
Ad 2) The fully completed 3D printed ceria structure demonstrated critical manufacture capabilities. Currently, a new geometry beyond the state of the art is under production, which will be tested in the 5-kW reactor and which has been optimized for reaching high absorption of direct light & high and homogeneous temperature distribution.