Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - SUN-to-LIQUID (SUNlight-to-LIQUID: Integrated solar-thermochemical synthesis of liquid hydrocarbon fuels)

Teaser

Decarbonising the transport sector is a major societal challenge. In the long-term perspective, electrification or hydrogen can provide solutions, but certain sub-sectors such as aviation will still rely on liquid hydrocarbon fuels. As the sustainable production potential of...

Summary

Decarbonising the transport sector is a major societal challenge. In the long-term perspective, electrification or hydrogen can provide solutions, but certain sub-sectors such as aviation will still rely on liquid hydrocarbon fuels. As the sustainable production potential of biofuels is limited, radically different non-biomass non-fossil fuel production pathways must be developed. SUN-to-LIQUID is such a technology that has the potential to meet future renewable fuel demand with a high potential for greenhouse gas emission reduction. SUN-to-LIQUID hydrocarbon fuel is produced from the abundant feedstocks H2O, CO2 and solar energy without the conflict of using arable land. Therefore, in the long term it may have a profound impact not only on minimizing the carbon footprint of e.g. aviation but also on the positive socio-economic development of economically challenged regions with arid climate, high levels of solar radiation and non-arable land, and on long-term energy supply security worldwide.

The primary objective of SUN-to-LIQUID is the scale-up and experimental validation of the complete process chain to solar liquid hydrocarbon fuels from H2O, CO2 and solar energy from the laboratory to the field at a pre-commercial scale. The project will thus advance solar fuel technology well beyond the state of the art and will provide the knowledge and technological roadmap for further scale-up towards a reliable basis for competitive industrial exploitation.

At the core of the new technology is a thermochemical redox cycle based on metal oxide material, driven by concentrated solar radiation, utilizing the full solar spectrum and operating at high temperatures. It therefore provides a thermodynamically favorable path to solar fuel production with high sunlight-to-fuel energy conversion efficiency and, consequently, economic competitiveness. In 2014, the first-ever production of solar jet fuel was experimentally demonstrated using a laboratory-scale solar reactor containing a ceria-based reticulated porous ceramic structure. SUN-to-LIQUID aims at advancing this solar fuel technology from the laboratory to the field with a 30-fold increase in specific yield, thereby developing key innovations such as an advanced high-flux ultra-modular solar heliostat field, a 50-kW solar reactor, and optimized redox materials to produce synthesis gas that is subsequently processed to liquid hydrocarbon fuels.

Work performed

The current report covers the first year of a four-year project. Significant progress has already been made in establishing a unique solar-chemical research facility and first results have been achieved, some of which were already published. For example, at the SolarPACES conference in September 2016, the design for the “ultra-modular 500-m2 heliostat field for high flux/high temperature solar-driven processes” was published by M.Romero, J.González-Aguilar and S. Luque.
Beyond the design of the plant, the main progress during the first year has been in establishing the actual experimentation infrastructure comprising

1) a high-flux solar concentrating subsystem
2) a solar thermochemical reactor subsystem, and
3) a gas-to-liquid conversion subsystem.

Meanwhile significant progress on construction and commissioning of the facility in Mostoles, Spain, has been achieved. Figure 1 is a picture of the facility, as seen from the rooftop of the IMDEA institute. The up-scaled solar thermochemical reactor was designed, build, and tested by Prof. Steinfeld’s group at ETH Zurich, Switzerland using a high flux solar simulator radiation source delivering 60% nominal reactor power (30 kW). Thereby significant progress in material development has been achieved on large-scale reticulated porous ceramic (RPC) ceria structures, resulting in the capability to reliably fabricate large ceria RPCs with high strength and good heat and mass transfer performance for a 50-kW reactor. Also completed were the key steps towards the design of flux measurement systems for the concentration facility by DLR, Germany, the design of the interfaces between all system components, and the gas-to-liquids subsystem which is under construction at HyGear in The Netherlands.

Final results

The progress beyond the state of the art in the first project year is partly represented by innovations with the high-flux solar concentration facility, as outlined by Romero et al. at the SolarPACES conference in September 2016 (see above), and partly in recent reactor innovations yet in the process of evaluation. The solar concentrator assembly makes use of the most recent developments on small-size 1.9-m by 1.6-m heliostats, in a compact 169 mirrors field assembly. In spite of its small size and compactness, the heliostat field is capable of delivering an average flux above 2500 kW/m2 at a level of at least 50 kW into an aperture of 16 cm diameter, with a peak flux of 3000 kW/m2. This high concentration ratio is enabled by the development of focusing prototype mirrors with short focal length, by an order of magnitude shorter than that of conventional facets supplied to commercial CSP plants. A specific development for facet manufacturing with cold mechanical bending was successfully tested and subsequently implemented. This technology may be exploited in future high-flux concentration facilities.

A wider impact is expected from the integration of all subsystems into a pioneering solar fuel facility later in the project. Also later in the project, this research facility and the capabilities developed by all partners will strengthen Europe’s competitive position in attracting best researchers worldwide and in pioneering innovations in solar fuel technology.

In the long term, the expected potential socio-economic impact of large-scale production of solar fuel is two-fold, energy supply security and wealth from local fuel production. The potential to reduce the dependency of oil producing countries for the supply of hydrocarbon fuels and thus to establish supply security is a strong driver for high-insolation regions such as in southern Europe, Africa and Australia.

The SUN-to-LIQUID technology requires a large solar resource of direct normal insolation (DNI) which is typically found in countries with vast areas of arid non-arable land. The construction of large-scale production facilities could therefore bring wealth to economically challenged regions and help to develop local industries and economies. As this is a new technology, it would not displace an existing industry but would be complementary and therefore create new jobs and opportunities. It is conceivable that the construction of a solar fuel plant with its necessary water provision could supply a surplus of fresh water to the local population and agriculture with a profound and sustainable positive socio-economic impact.

Website & more info

More info: http://www.sun-to-liquid.eu/.