This Solar Tower Generates Jet Fuel From Water and Light

A team of researchers have created a tower capable of using solar radiation, water, and carbon dioxide to create synthetic kerosene—jet fuel—instead of relying on fossil fuels.

“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, a professor from ETH Zurich and a co-author of the paper, said in a release.

Typically, kerosene (jet fuel) is derived from fossil fuels by fractionally distilling crude oil. That fuel source goes on to play a key role in aviation across the world, ranging from international trade to domestic transport. As a result, the aviation sector is responsible for about five percent of global carbon emissions, a number that is expected to grow. 

For that reason, there's been attempts to create kerosene without fossil fuels for years now. In October, the Air Force announced it made progress in a project turning carbon dioxide into "operationally viable aviation fuel" called E-Jet so that targets of airstrikes might sleep easy knowing the jets raining down death were at least carbon neutral. Twelve, the company the Air Force partnered with, has gone on to partner with Alaska Airlines and Microsoft to roll out the “carbon-neutral” jet fuel. Others have simply tried to reduce the mix of fossil fuels in the kerosene itself to make a more “sustainable” variant. In 2020, Davos offered “sustainable aviation fuel” for participants flying in on their private jets, a brave gesture being replicated by companies like fossil fuel giant ExxonMobil as they figure out how to maximize oil revenues even as this shift occurs.

Still, these projects have been limited by the practicality of scaling up the production of alternatives using solar power and integrating them into global jet fuel infrastructure so they can be easily produced, distributed, and stored. 

As outlined in a new study published on Wednesday in Joule, A research team based in Spain built and test-drove a solar fuel-production plant featuring 169 sun-tracking panels that concentrate solar radiation into a reactor atop the tower. The concentrated energy is then used to drive chemical reactions in the solar reactor that help convert water and CO2 into a synthesis gas (carbon monoxide and hydrogen), which is then converted into liquid, then converted into liquid hydrocarbon fuels. 

“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 kerosene combustion in a jet engine equals that consumed during its production in the solar plant,” Steinfeld says. “That makes the fuel carbon neutral, especially if we use CO captured directly from the air as an ingredient, hopefully in the not-too-distant future.”

The project was undertaken under the auspices of the EU's SUN-to-LIQUID project. And even though the solar tower design still had some efficiency shortfalls, the researchers maintain that "it has the potential to reach competitive values of over 20%," according to the study, by making tweaks such as improving heat recovery.