As the world faces rising energy demands and climate concerns, scientists are working on new ways to create clean, sustainable fuels.
One promising solution is using sunlight—not just for electricity, but to power chemical reactions that make fuel.
This could be especially important for industries like aviation, where carbon-based fuels are still widely used.
A team at Caltech, part of the Department of Energy’s Liquid Sunlight Alliance (LiSA), has created a small-scale device that uses solar heat to help make jet fuel.
This device, called a photothermocatalytic reactor, runs completely on solar energy and doesn’t need fossil fuels or electricity to work.
The reactor includes a special solar absorber that captures as much sunlight as possible while keeping heat from escaping.
It’s built with several layers of materials like silicon, germanium, and gold on a silver base.
Each layer plays a role in collecting and holding onto solar heat. A clear quartz window on top lets sunlight in, while a vacuum layer helps prevent heat loss. The solar absorber sits directly on top of the chemical reactor.
Under normal sunlight, the system can heat up to 249°C, and it stays around 130°C during everyday use. That heat is enough to power a key chemical reaction called ethylene oligomerization, which is used to create longer hydrocarbon chains—building blocks of jet fuel.
In simple terms, the team used sunlight to convert ethylene, a small hydrocarbon molecule, into alkenes—liquid fuel molecules with more carbon atoms. Jet fuel typically contains hydrocarbon chains with 7 to 26 carbon atoms, and the team successfully produced this range using only solar energy.
Unlike some solar technologies that need to follow the sun’s movement across the sky (known as solar tracking), this new system works without tracking. That makes it cheaper and easier to use, especially in areas where complex solar systems aren’t practical.
While the current process starts with ethylene made from fossil fuels, the LiSA team recently showed it’s also possible to create ethylene from just carbon dioxide, water, and sunlight. This means they’ve now demonstrated two clean steps powered entirely by the sun: first making ethylene, then turning it into fuel.
“This shows we can use the sun’s heat to drive important chemical reactions that usually need fossil fuels,” said Professor Harry Atwater, the project leader.
This exciting breakthrough brings us a step closer to producing jet fuel with net-zero carbon emissions, all powered by the clean and abundant energy of sunlight.
Source: Caltech.
