Xiangkun (Elvis) Cao

Xiangkun (Elvis) Cao, 32, wants to make air travel carbon-neutral. He’s created a device that mimics photosynthesis and turns carbon dioxide into airplane fuel. 

Air travel makes up 2% of global carbon emissions, according to the International Energy Agency. Artificial photosynthesis, whereby scientists combine light, carbon dioxide, and water in a reactor to create synthetic fuel, has shown promise as a decarbonization tool. But researchers have struggled to make the technology scalable, low-cost, and efficient.  

Using a photocatalytic reactor to convert CO₂ into useful chemicals is not new, but Cao’s reactor stands out. Its efficient delivery of light, hydrogen, CO₂, and heat is a feat of interdisciplinary engineering. Drawing from the field of optics, Cao uses a waveguide, which focuses light onto the area where the reaction takes place. At the same time, a special panel called a baffle (used in everything from household stoves to rocket engines) efficiently mixes CO₂ and hydrogen. To keep the reactor at the ideal temperature, phase-change materials emit and absorb heat as they solidify and melt. 

His device converts about half of the CO₂ it absorbs into carbon monoxide, a percentage 20 times higher than similar reactors. The carbon monoxide is then mixed with hydrogen to make an essential jet fuel ingredient.  

United Airlines has agreed to purchase 300 million gallons of synthetic fuel from the spinoff based on his technology, over the next 20 years. The flights powered by these fuels will still emit carbon dioxide, which makes them carbon-neutral but not carbon-negative. 

Cao, who completed his PhD in mechanical engineering at Cornell, hopes to someday design a device that could be attached directly behind a plane’s exhaust pipes. There, the device could convert emitted CO₂ into fuel in real time, preventing the greenhouse gas from ever entering the atmosphere.

This post has been updated.