By Neil Bowdler, Science reporter, BBC News
23 December 2010 Last updated at 14:11 ET
A prototype solar device has been unveiled which mimics plant life, turning the Sun's energy into fuel.
The machine 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.
Conventional photovoltaic panels must use the electricity they generate in situ, and cannot deliver power at night.
Details are published in the journal Science.
The prototype, which was 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.
Ceria has a natural propensity to exhale oxygen as it heats up and inhale it as it cools down.
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. …
The prototype is grossly inefficient, the fuel created harnessing only between 0.7% and 0.8% of the solar energy taken into the vessel.
Most of the energy is lost through heat loss through the reactor's wall or through the re-radiation of sunlight back through the device's aperture.
But the researchers are confident that efficiency rates of up to 19% can be achieved through better insulation and smaller apertures. Such efficiency rates, they say, could make for a viable commercial device. …