Researchers develop carbon-neutral fuel for aviation industry

Scientists have built an aviation fuel production system that uses water, carbon dioxide (CO2), and sunlight. They put the system into action and the design, which was released on July 20e2022, in the review Joulecould help the aviation industry on its journey towards eliminating carbon emissions.

Solar tower fuel plant during operation. Image Credit: IMDEA Energy

We are the first to demonstrate the entire thermochemical process chain from water and CO2 to kerosene in a fully integrated solar tower system.

Aldo Steinfeld, Professor, Corresponding Author of the Study, ETH Zurich

Previous efforts to generate aviation fuels using solar energy have mostly been done in the laboratory.

The aviation industry is responsible for about 5% of global anthropogenic emissions that cause climate change. It relies heavily on kerosene, also known as jet fuel, which is a liquid hydrocarbon derived primarily from crude oil. Currently, there are no clean options available to power long-haul commercial flights globally.

With our solar technology, we have shown that we can produce synthetic kerosene from water and CO2 instead of deriving it from fossil fuels. The amount of CO2 emitted during the combustion of kerosene in a turbojet engine is equal to that consumed during its production in the solar power plantsays Steinfeld. “This makes the fuel carbon neutral, especially if we use CO2 captured straight from the air as an ingredient, hopefully in the not too distant future.”

Steinfeld and his colleagues have proposed a system that uses solar energy to generate alternative fuels, which are synthetic options for fossil fuels like kerosene and diesel, as part of the SUN-to-LIQUID project. of the European Union.

According to Steinfeld, kerosene produced by solar energy is perfectly compatible with the current aviation infrastructure for the storage, allocation and use of fuel in jet engines. He adds that it can also be fused with fossil fuel kerosene.

In 2017, the team began scaling up the design and construction of a solar fuel fabrication plant at the IMDEA Energy Institute in Spain. The plant is made up of 169 reflective panels that track the sun and redirect and concentrate solar radiation into a tower-mounted solar reactor. The concentrated solar energy then powers oxidation-reduction (redox) reaction cycles in the porous cerium structure of the solar reactor.

Cerium oxide, which is not absorbed but can be reused, converts water and CO2 injected into the reactor with synthesis gas, a personalized mixture of hydrogen and carbon monoxide. The syngas is then fed to a gas-to-liquid converter, where it is converted into liquid hydrocarbons such as kerosene and diesel.

This solar tower fuel plant was operated with a configuration suitable for industrial implementation, establishing a technological milestone towards the production of sustainable aviation fuels.

Aldo Steinfeld, Professor, Corresponding Author of the Study, ETH Zurich

The energy efficiency of the solar reactor – the part of the solar energy input that is transformed into total energy from the syngas produced – was around 4% during a nine-day operation of the reported plant. in the article.

Steinfeld says his team is working hard to improve the design to increase efficiency to values ​​above 15%. For example, they are studying ways to optimize the structure of cerium oxide for the absorption of solar radiation and developing techniques to recover the heat generated during redox cycles.

Journal reference:

Zoller, S. et al. (2022) A solar fuel tower for the thermochemical production of kerosene from H2O and CO2. Joule.