Conventional fuels from concentrated sunlight | Discover | University of Minnesota - 0 views
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Gary Edwards on 23 Feb 14"Simulated sun, authentic opportunity" At the University's Solar Energy Laboratory, the process begins with an indoor solar simulator in the form of seven mirrored, 6,500-watt lamps that concentrate the light on a 10-centimeter spot with an irradiance of 3,000 suns. (One "sun" equals 1,000 watts of solar energy falling per square meter of surface.) With this concentrated radiant energy, one can generate temperatures of more than 3,600 F in a chemical reactor. There, carbon dioxide and water are split to form carbon monoxide and hydrogen, the two components of syngas. Davidson, along with mechanical engineering professor Tom Chase and their students, have developed two prototype reactors to split water and CO2. Deploying these technologies in the Earth's sunbelt could yield enough renewable energy to significantly exceed the world's current needs, the researchers say. "More sun falls on Earth in one hour than is consumed globally in a year," Davidson notes. "Harvesting the sun to meet our energy needs is a challenge with a huge payoff." Of course, it's a little more complicated than focusing concentrated sunlight into a reactor filled with carbon dioxide and water. The key to the technology rests with using metal oxides in a reduction/oxidation cycle to reduce the temperature required to split water and carbon dioxide. "Metal oxides allow you to split water and carbon dioxide at temperatures achievable with modern solar concentrating devices," Davidson explains. In the reactor, the metal oxides go through cycles in which they strip oxygen alternately from carbon dioxide or water-forming carbon monoxide or hydrogen, respectively-then release the oxygen as a byproduct. The syngas formed from the carbon monoxide and hydrogen can be converted into gasoline, diesel, jet fuel, methane (natural gas), or other products. Davidson and her colleagues have produced syngas this way in their laboratory. They have moved from bench top experiments to demonstration in proto