This tale appeared in the July/Aug 2020 difficulty as “The Other Photo voltaic Electrical power.” Subscribe to Explore magazine for more stories like this.

Couple of actions swell our carbon footprint quite like traveling. A one particular-hour flight on a twin-motor jet plane burns pretty much six,000 pounds of kerosene and adds pretty much 19,000 pounds of carbon dioxide to the ambiance. The environmental effects of air travel is so stark that Swedes even have a time period for it: flygskam, or flight disgrace. But what if traveling could be built zero carbon?

“We have produced a solar engineering that is capable to make liquid fuels working with just two ingredients: solar strength and ambient air,” suggests Aldo Steinfeld, a renewable strength specialist at the Swiss Federal Institute of Know-how. “These hydrocarbon fuels launch only as much carbon dioxide in the course of combustion as was beforehand extracted from the air.”

It may perhaps appear to be like alchemy, but the solar refinery Steinfeld has assisted build in Móstoles, on the outskirts of Madrid, follows some straightforward chemistry. An array of mirrors named a heliostat tracks the solar, boosting the sunlight’s depth by a variable of 2,500 while reflecting it on to a 50-foot-significant tower.

This stunning beam of gentle heats a reactor with a core built of cerium oxide, an affordable compound often used to polish glass. At 2,seven-hundred degrees Fahrenheit, oxygen is liberated from the cerium and eradicated, just after which h2o and carbon dioxide captured from the air are injected into the reactor. As the reactor cools, the decreased cerium claws back oxygen molecules from the included material, leaving a combination of hydrogen and carbon monoxide named syngas. This is funneled into a 2nd reactor, wherever the syngas is converted into kerosene molecules. In June 2019, the Móstoles refinery introduced its first trickle of fuel.

But why switch solar strength into fuel at all? While street and rail transport are open up to electrification, current battery engineering does not pack the punch required to travel heavy industries this kind of as sea freight and air travel. “There is no way all-around jet fuel for long-haul professional aviation,” suggests Steinfeld. “Can you imagine a Boeing or Airbus traveling trans-Atlantic on batteries? I consider it violates the legislation of physics.”

Photo voltaic kerosene has the potential to slot into current international infrastructure for storing, transporting and working with fossil fuels. But it still can’t contend with them for selling price: It would probable ring up all-around $9 for each gallon if it’s bought to shoppers. But that cost ought to drop as the engineering improves in performance and grows in scale. Steinfeld believes that, with a modest boost in current performance, solar refineries could provide the complete world’s jet aviation fuel demand from customers with a heliostat array the sizing of Indiana.

This revolution is underway. Very last Might, a significant airport in the Netherlands introduced it would host the world’s first plant turning atmospheric carbon dioxide into liquid fuel. Climeworks — a firm spun out from Steinfeld’s lab in 2009 — is supplying the modules that will capture carbon dioxide from the air.

And what of our flygskam? “If the jet fuel is created from daylight and air, then there is almost nothing to be ashamed of because the carbon footprint would be zero,” suggests Steinfeld. “A real sustainable system.”

Frank Swain is a science writer centered in Barcelona, Spain.