Scientists at Caltech have developed a new solar-powered device that could one day help make jet fuel without adding extra carbon to the atmosphere.
As energy demands grow and climate change worsens, finding cleaner energy sources has become more urgent—especially in areas like aviation, where carbon-based fuels are still widely used.
To help solve this problem, a research team from Caltech, working with the U.S. Department of Energy’s Liquid Sunlight Alliance (LiSA), created a small device that uses sunlight—not fossil fuels or electricity—to produce heat for making jet fuel.
This device, called a photothermocatalytic reactor, captures sunlight and turns it into heat to power a chemical reaction needed for creating fuel.
What makes this system special is its selective solar absorber—a part designed to soak up as much sunlight as possible while keeping heat from escaping.
To do this, the team built a layered structure using materials like silicon, germanium, gold, and silver. Each layer plays a specific role, and together they help the system get hot enough to drive chemical reactions using only sunlight.
A quartz window on top lets sunlight in, and a vacuum layer helps trap the heat. Under normal conditions, the absorber can reach up to 130°C, and up to 249°C under full sunlight—enough to carry out useful chemical processes.
In their experiment, the Caltech team used the device to perform ethylene oligomerization, a reaction that turns small hydrocarbon molecules into longer ones.
These longer chains, called alkenes, are similar to the ones found in jet fuel. Until now, this kind of reaction has usually needed heat from burning fossil fuels. But this new system managed to do it using only solar energy.
Interestingly, while this study used ethylene made from fossil fuels, the team recently showed it’s possible to make ethylene from carbon dioxide (CO₂), water, and sunlight. That means, in the future, both the starting materials and the energy needed could come from renewable sources—making the process truly carbon-neutral.
Another big plus? This system doesn’t need expensive solar tracking equipment, which moves panels to follow the sun. Instead, the reactor works at a fixed position, making it cheaper and easier to use in more locations.
This early-stage research shows great promise.
If the technology can be scaled up, it could help the aviation industry take a big step toward reducing its carbon footprint—using nothing but sunlight and smart science.
