Synhelion -- Using solar heliostat farms to create liquid fuels from Water Vapor and CO2

[berkeman]

Has anybody looked at this technology? I came across it in the latest National Geographic magazine in an article about the Pictures of the Year, and it sounds like an interesting idea.

https://synhelion.com/

The idea is to use the very high temperatures in the solar collection tower of a heliostat farm to perform the reverse chemical process of combustion:

Is it really possible to reverse combustion?​

Yes, it is. When conventional fuels are burnt with oxygen, they release heat, CO2, and water vapor. Synhelion’s technology reverses this process. With the help of solar heat, we recombine water vapor and CO2 into hydrocarbon fuels.

And since CO2 is used in the production of these liquid fuels, they are claiming that the overall process of producing the fuel and burning it is carbon neutral.

The liquid fuels produced by the process can be tuned to be close to kerosene or gasoline. They are initially targeting certain transportation markets where electrification is difficult:

What markets do you focus on?​

Synhelion’s mission is to support the defossilization of the transportation sector, especially those sectors that are difficult to electrify, such as aviation and shipping.
In road transportation, electrification plays a key role in reducing CO2 emissions. While electromobility can be rolled out quickly in some regions of the world, such as Europe, it will take much longer in other regions to significantly reduce the number of vehicles with internal combustion engines (ICE). Studies show that there will be many remaining ICE vehicles around the world that will also need to be powered sustainably to meet net-zero emission targets by 2050. As a complementary solution to road electrification, Synhelion’s solar fuels can help achieve these targets.

What is new about your technology? Why hasn’t it been developed before?​

Thermochemical production of solar fuels requires extremely high process temperatures. We solved key challenges in the transformation of solar radiation into process heat and in thermal energy storage. Furthermore, we developed a unique technology to produce syngas. By combining these innovation fronts, we can achieve unprecedented efficiency.

Here are some of the journal articles that they list at their website about their technology:

Synhelion partners with top-tier research labs and conducts cutting-edge research. See below for a selection of our most important publications.

• Zuber, M., Patriarca, M., Ackermann, S., Furler, P., Conceição, R., Gonzalez-Aguilar, J., Romero, M., Steinfeld, A., “Methane dry reforming via a ceria-based redox cycle in a concentrating solar tower”. Sustainable Energy & Fuels, 8 (2023).
• Schäppi, R., Rutz, D., Dähler, F., Muroyama, A., Haueter, P., Lilliestam, J., Patt, A., Furler, P., Steinfeld, A., “Drop-in fuels from sunlight and air”. Nature (2021).
• Ambrosetti, G., Good, P., “A novel approach to high temperature solar receivers with an absorbing gas as heat transfer fluid and reduced radiative losses”. Solar Energy, 183, 521–531 (2019).
• Furler, P., Scheffe, J., Marxer, D., Gorbar, M., Bonk, A., Vogt, U., Steinfeld, A., “Thermochemical CO2 splitting via redox cycling of ceria reticulated foam structures with dual-scale porosities”. Physical Chemistry Chemical Physics 16, 10503–10511 (2014).
• Marxer, D., Furler, P., Scheffe, J., Geerlings, H., Falter, C., Batteiger, V., Sizmann, A., Steinfeld, A., “Demonstration of the entire production chain to renewable kerosene via solar thermochemical splitting of H2O and CO2”. Energy & Fuels (2015).
• Furler, P., Scheffe, J. R., Steinfeld, A., “Syngas production by simultaneous splitting of H2O and CO2 via ceria redox reactions in a high-temperature solar reactor”. Energy & Environmental Science 5, 6098–6103 (2012).
• Marxer, D., Furler, P., Takacs, M., Steinfeld, A., “Solar thermochemical splitting of CO2 into separate streams of CO and O2 with high selectivity, stability, conversion, and efficiency”. Energy & Environmental Science 10, 1142–1149 (2017).
• Ackermann, S., Scheffe, J., Steinfeld, A., “Diffusion of oxygen in ceria at elevated temperatures and its application to H2O/CO2-splitting thermochemical redox cycles”. The Journal of Physical Chemistry, 118, 5216–5225 (2014).
• Geissbühler, L., “Thermocline thermal energy storage: advances and applications to CSP, compressed air energy storage, and solar fuels”. Diss ETH No. 24555, (2017).
• Geissbühler, L., Kolman, M., Zanganeh, G., Haselbacher, A., Steinfeld, A., “Analysis of industrial-scale high-temperature combined sensible/latent thermal energy storage”. Applied Thermal Engineering 101, 657–668 (2016).
• Geissbühler, L., Mathur, A., Mularczyk, A., Haselbacher, A., “An assessment of thermocline-control methods for packed-bed thermal-energy storage in CSP plants, Part 1: Method descriptions”, Solar Energy 178, 341–350 (2019).
• Dähler, F., Wild, M., Schäppi, R., Haueter, P., Cooper, T., Good, P., Larrea, C., Schmitz, M., Furler, P., Steinfeld, A., “Optical design and experimental characterization of a solar concentrating dish system for fuel production via thermochemical redox cycles”. Solar Energy, 170, 568–575 (2018).
• Chueh, W., Falter, F., Abbott, M., Scipio, D., Furler, P., Haile, S., Steinfeld, A., “High-flux solar-driven thermochemical dissociation of CO2 and H2O using nonstoichiometric ceria”. Science, 330, 1797-1801, 2010.
• Ackermann, S., Scheffe, J., Duss, J., Steinfeld, A., “Morphological characterization and effective thermal conductivity of dual-scale reticulated porous structures”. Materials, 7, 7173-7195 (2014).
• Moretti, C., Patil, V., Falter, C., Geissbühler, L., Patt, A., Steinfeld, A., “Technical, economic and environmental analysis of solar thermochemical production of drop-in fuels”. Science of the Total Environment, 901, 166005 (2023).