Saturday Dec 03, 2022

Sustainable Aviation Fuel From Solar Energy: Not A Dream Any More – CleanTechnica


The search for sustainable aviation fuel was once dominated by biofuel stakeholders, but the aviation industry could take off in a new direction that skips the plant-based middleperson in favor of a straight line from solar energy to liquid kerosene. In the latest development on that score, the Swiss institution ETH Zurich has just unveiled a new pilot-scale, all-in-one, solar powered process for converting water and carbon dioxide straight into into jet fuel.

The Green Hydrogen Angle On Liquid Fuel From Solar Energy

If you guessed green hydrogen is somewhere in the mix, that would be correct. ETH Zurich (the Swiss Federal Institute of Technology in Zurich), describes its pilot project as a thermochemical process that deploys solar energy in a single, integrated chain that goes from hydrogen gas, oxygen and carbon dioxide to liquid kerosene fuel in a “solar tower.”

“We evaluate the performance of the solar reactor − the cornerstone technology − based on five primary metrics (namely: reaction selectivity, syngas quality, fuel purity, energy efficiency, and material stability) and experimentally validate its stable operation and full integration in the solar tower fuel plant,” ETH explains. They list the following highlights of the project:

  1. Entire process chain from H2 O and CO2 to solar kerosene realized in a solar tower
  2. 50-kW solar reactor demonstrated for ceria-based thermochemical redox splitting
  3. Consecutive redox cycling produced syngas suitable for Fischer-Tropsch synthesis
  4. 4.1% solar-to-syngas energy efficiency achieved without implementing heat recovery

CleanTechnica got advance word on the results of the demonstration under embargo, which will be lifted by the time you read this. The details should be available in the journal Joule at DOI 10.1016/j.joule.2022.06.012.

A press release may also be forthcoming from the ETH media office, and in the meantime you can find more info elsewhere on the ETH website regarding their solar energy to fuel research.

Solar Energy To Liquid Fuel, Not A Dream

If all this sounds like it popped up out of nowhere, that’s probably because biofuels have dominated most of the attention in the sustainable aviation fuels area. CleanTechnica has covered many different angles in the biofuel area including bio-waste products, algae, seaweed, and waste paper, among others.

Meanwhile, activity in the electrofuel area has been stirring. Wind power can get the e-fuel job done on the green hydrogen side, but the ETH project demonstrates how solar energy can come into play, too.

There being no such thing as a free lunch, the road to commercial-scale solar fuel has been a long one. The research goes back to at least 2011, under the Solar-Jet project that concluded in 2015.

In 2014, our friends over at Chemistry World took note of the obstacles encountered by the Solar-Jet project, further noting that three years of work had resulted in a single glass of kerosene.

“Unfortunately, the idea has suffered from two problems. One is that the dissociation of carbon dioxide and water only takes place at very high temperatures, typically above 2200°C. But the other, more difficult, problem is that the syngas cannot be tackled by the Fischer–Tropsch process until all the oxygen is removed as it is dangerously explosive,” they wrote, while observing that the concentrating solar pathway would resolve the first problem.

ETH seems to have taken the ball and run with it. The institute went on to participate in the EU/Swiss “Sun-to-Liquid” project, …….


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