Hydrogen fuel from sunlight and water?

The technique involves splitting water into its components of hydrogen and oxygen. The University of Colorado Boulder team devised a solar-thermal system in which sunlight can be concentrated by a vast array of mirrors onto a single point atop a central tower up to several hundred feet tall. "The tower would gather heat generated by the mirror system to roughly 1,350ºC, then deliver it into a reactor containing chemical compounds known as metal oxides," noted project leader Professor Alan Weimer. As a metal oxide compound heats up, it releases oxygen atoms, changing its material composition and causing the newly formed compound to seek out new oxygen atoms. The team showed that the addition of steam to the system - which could be produced by boiling water in the reactor with the concentrated sunlight beamed to the tower - would cause oxygen from the water molecules to adhere to the surface of the metal oxide, freeing up hydrogen molecules for collection as hydrogen gas. "We have designed something here that is very different from other methods and frankly something that nobody thought was possible before," said Prof Weimer. "Splitting water with sunlight is the Holy Grail of a sustainable hydrogen economy."