New solar fuel device that mimics plant life

Scientists have unveiled a prototype solar device that mimics plant life, turning the Sun's energy into fuel.

The device uses the Sun's rays and a metal oxide called ceria to break down carbon dioxide or water into fuels, which can be stored and transported.

The prototype, which has been devised by researchers in the US and Switzerland, uses a quartz window and cavity to concentrate sunlight into a cylinder lined with cerium oxide, also known as ceria.

If as in the prototype, carbon dioxide and/or water are pumped into the vessel, the ceria will rapidly strip the oxygen from them as it cools, creating hydrogen and/or carbon monoxide.

Hydrogen produced could be used to fuel hydrogen fuel cells in cars, for example, while a combination of hydrogen and carbon monoxide can be used to create "syngas" for fuel.

It is this harnessing of ceria's properties in the solar reactor, which represents the major breakthrough, said the inventors of the device.

They also said the metal is readily available, being the most abundant of the "rare-earth" metals.

The prototype, however, is grossly inefficient, the fuel created harnessing only between 0.7% and 0.8% of the solar energy taken into the vessel.

But the researchers are expecting that the efficiency rates would go up to 19% through better insulation and smaller apertures.

"The chemistry of the material is really well suited to this process. This is the first demonstration of doing the full shebang, running it under (light) photons in a reactor," the BBC quoted Sossina Haile of the California Institute of Technology (Caltech), as saying.

The reactor could be used to create transportation fuels or be adopted in large-scale energy plants, where solar-sourced power could be available throughout the day and night, she said.

However, she admitted the fate of this and other devices in development is tied to whether states adopt a low-carbon policy.

"It's very much tied to policy. If we had a carbon policy, something like this would move forward a lot more quickly," she said.

The findings were reported in the journal Science.