Carbon-neutral solar fuel prototype developed in Zurich

The solar reactor on the roof of the ETH, Sonneggstrasse, Zurich. Alessandro Della Bella

A Swiss research team has unveiled technology than can produce car and plane-ready fuel from nothing but air and water, a discovery with potentially big consequences for transport and the environment.

Presenting their “mini-refinery” as a global first, scientists from the Swiss Federal Institute of Technology Zurich (ETHZ) say that the solar panels can produce synthetic liquid fuels that release only as much CO2 in combustion as was previously extracted from the air for production.

In their prototype solar plant (on a rooftop in Zurich, see photo), “CO2 and water are extracted directly from ambient air and split using solar energy”, according to a press releaseExternal link. The resultant gas mixture can then be processed into kerosene, methanol or other hydrocarbons.

“This plant proves that carbon-neutral hydrocarbon fuels can be made from sunlight and air under real field conditions,” said Aldo Steinfeld, Professor of Renewable Energy Carriers at ETHZ.

Around one decilitre of fuel is produced daily by the small reactor; another, larger prototype is currently being built by the same research team on a solar tower near Madrid, in Spain.

Economically feasible?

The researchers are confident that in the future the technology can be made industrially viable and economically competitive. “Theoretically, a plant the size of Switzerland – or a third of the Californian Mojave Desert – could cover the kerosene needs of the entire aviation industry,” said Philipp Furler, Director of Synhelion, a commercial solar fuel production group.

The technology adds to growing efforts to come up with ways to ensure a carbon neutral, environmentally sustainable future; this includes innovation to remove CO2 from the atmosphere, a field in which Switzerland is also a leader.

Also this week, in a separate project, researchers at the Federal Institute of Technology Lausanne (EPFL) announced that they had discoveredExternal link a method of using iron atoms to convert CO2 from burning fossil fuels directly into carbon monoxide – an essential ingredient for synthetic fuels, as well as plastics and other materials.

Their results were published on Friday in the Science magazine.