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chrb writes "Scientists from the California Institute of Technology and the Swiss Federal Institute of Technology have unveiled a new solar reactor prototype that directly converts carbon dioxide or water into carbon monoxide or hydrogen, respectively. The abstract is available in Science. Quoting the BBC writeup:
'The prototype ... 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. ...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."
The perversity of nature is nowhere better demonstrated by the fact that, when
exposed to the same atmosphere, bread becomes hard while crackers become soft.