Co-funded by the EU and Switzerland, the European research project SUN-to-LIQUID II was launched on 1 November 2023. Leading partner institutions from academia and industry will demonstrate scalability and high efficiency in the production of sustainable hydrocarbon fuel from water, CO2 and concentrated sunlight via high-temperature chemical conversion.

What is SUN-to-LIQUID II about

The European Commission (EC) aims to eliminate net greenhouse gas (GHG) emissions on the path to climate neutrality by mid-century. The transportation sector will play an important role in the transition to a society living on 100% renewable energy. Two key challenges towards achieving this target relate to (i) an increased feedstock basis for renewable fuel production and (ii) the long-term development of sustainable fuel technologies for aviation.

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. First-generation biofuels cannot meet the required volumes, due to availability and sustainability constraints. Hence, scalable technologies will be required to meet the longer-term fuel demand. Solar radiation is the most scalable form of renewable energy.

SUN-to-LIQUID II will develop 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 fuel from the inexhaustible potential of solar energy.

The partnership

The SUN-to-LIQUID II consortium consists of six partners from five European countries (Spain, Germany, Switzerland, Netherlands, and France), under the coordination of Bauhaus Luftfahrt e. V. This unique partnership between research institutes and industry aims to bridge the gap between research and industrial applications in high-temperature sunlight-driven chemistry. Leading international research institutes in the field of solar thermochemistry, German Aerospace Center (DLR) and Fundacion IMDEA Energía, collaborate on the improvement of the solar concentrator and the plant operation at the IMDEA Technology Park in Móstoles, Spain. Furthermore, IMDEA tests and implements novel 3D-printed structured redox materials and DLR develops the solar reactor with integrated heat recovery. The industrial partner HyGear BV contributes the conversion of the solar synthesis gas to liquid fuels. The ETH spin-off and industry leader for high-temperature solar chemistry, Synhelion SA, provides the expertise for scaling up the prototype, and performs the exploitation analysis. Bauhaus Luftfahrt e.V. performs techno-economic, environmental, and socio-economic analyses in collaboration with consortium partners. Bauhaus Luftfahrt e.V. is supported by L-up, a French consultancy SME, in project coordination, as well as communication and exploitation activities, thanks to its vast expertise in EU projects.

Key innovations

SUN-to-LIQUID II taps into a virtually unlimited resource of sustainable fuel production by developing the technology and roadmap to produce high-quality renewable liquid fuel directly from water, CO2 and concentrated solar energy. The primary objective of SUN-to- LIQUID II is to increase the solar reactor energy efficiency to more than 15% by improving the effective radiative absorption using 3D-printed redox materials with optimized structure and by recovering sensible heat during the temperature swing redox process. It will bring key advancements from laboratory-scale research in redox material and heat recovery to validation in an industrially relevant environment. Besides, this project will provide evidence for cost-effective >80% GHG emission reduction especially for aviation, with technical scalability to production potentials beyond projected demand. The project is built on the preceding Horizon2020 project SUN-to-LIQUID which successfully demonstrated on-sun solar-thermochemical fuel production on a 50-kW scale.

As part of IMDEA Energy’s commitment to the effective transfer of R&D results to the productive sector, ABG Intellectual Property has recently collaborated in a theoretical and practical workshop with more than fifty researchers who are part of the staff.

Specifically, Juan Arias went to the auditorium of this institution together with our technical advisor and European Patent Agent, Virginia Gómez, and the head of the legal and litigation department, Laura Montoya. The Head of Development and Technology Transfer at IMDEA Energía, Félix Marín, was the organizer of the conference and speaker, which was also attended by Jesús Palma, a researcher at the center with which ABG frequently collaborates.

Patent applications in practice

The day was very complete, including a theoretical and a practical part. During the theoretical part, an introduction to the industrial and intellectual property protection system was given, which served as a basis for delving into other more specific concepts of patent protection. In addition, the lectures also included an analysis of the ways of obtaining benefits from protected inventions and a review of the types of contracts that are usually necessary in research center projects.

The attendees, for their part, were able to put into practice the knowledge acquired by applying it to several research project cases. Working in teams, the researchers faced the drafting of the claims of a patent application in collaboration with patent agents. At the end of the workshop, they shared their results with the rest of the participants and were surprised by their quality.

The Technical Committee of the Madrid+Circular Innovation Hub met at IMDEA Energía on September 14 to follow up on the progress of the different scientific tasks planned. During the meeting, representatives of the teams from Repsol (Rosa Parrilla, Sheyla Carrasco and Aitor Romero), Ariema (Enrique Girón, Javier Ángel Otero and Nicolás Alonso), Evoenzyme (Javier Viña), Seenso Renoval (José Ignacio Ajona) and IMDEA Energía (David Serrano, Manuel Romero, Javier Dufour, Javier Dufour, Javier Dufour, Javier Dufour and Nicolás Alonso), Manuel Romero, Javier Dufour, Jennifer Cueto and Félix Marín) shared their progress in the different tasks planned to develop the technologies that allow the use of all types of waste (urban waste, used plastics, different types of oils, . …) as raw materials to produce sustainable materials and fuels with the integration of renewable energy sources, as well as the strategies for the protection of industrial property and scientific publications resulting from the work carried out.

The conclusions obtained will serve as a contribution to the monitoring of the project by the Community of Madrid and will highlight both innovation and the use of the circular economy as a tool to achieve a more efficient and sustainable management through the use of waste as raw material, allowing its revaluation in high added value products with a lower carbon footprint and reducing the amount that ends up in a landfill.

The meeting was followed by a tour of the Institute’s laboratories, pilot plants and scientific facilities where the various materials synthesis and testing, flow battery energy storage and solar generation activities are carried out.