A solar tower to produce fuel for planes

Depending on how it is calculated, the climate impact of air travel ranges from less than 1% to around 5%. But what is certain is that it is essentially the result of combustion from kerosene which powers the reactors of our planes. Because kerosene is produced by refining from oila combustible fossil. Its combustion emits carbon dioxide (CO₂), the main greenhouse gas responsible for global warming anthropogenic. For the time being, unfortunately, there is no clean alternative that makes it possible to consider maintaining long-haul flight traffic on a global scale.

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For the time being… because scientists are far from admitting defeat in the field! Among the most promising avenues is the production of so-called solar fuels. The idea is to produce a synthetic fuel fromenergy solar. It is possible by photochemical way, by activating reactions thanks to photons which carry solar energy, or photobiologically, understand by photosynthesis artificial, for example. But also by thermochemical way.

It is this path that researchers at the Swiss Federal Institute of Technology Zurich (ETH, Switzerland) chose to explore. They are now showcasing a fuel production system that they hope could help the aviation sector become carbon neutral. A solar tower that produces jet fuel from water and CO₂.

This tower is made up of 169 panels that follow the course of the Sun by reflecting and concentrating the radiation towards a reactor located at the top. This energy then makes it possible to trigger cycles of reactions ofredox on the porous oxide structure cerium (CeO₂) — a compound that is not consumed in the operation — to convert water and CO₂ injected into the reactor as synthesis gas which will then be transformed into kerosene.

Efficiency that can be improved

Until now, such attempts had remained at the laboratory stage. This time, the researchers succeeded in demonstrating the feasibility of the entire chain on their demonstrator industrial. From CO₂water and light from the sun, they are able to produce kerosene.

Kerosene? But then the planes will continue to emit just as much CO₂ than before. Yes. But the solar tower developed by ETH researchers consumes as much CO₂ that planes then emit. What finally make the fuel carbon neutral. A little more even when it can be produced from a CO₂ captured directly in theair.

The other advantage is that solar kerosene is completely compatible with existing infrastructures. Storage, distribution and usage infrastructures. If necessary, it can be mixed with original kerosene fossil.

Only downside, finally, theenergetic efficiency of the solar tower. Today it is only about 4%. But the researchers already have ways to improve their design. They hope to increase it to 15%.