Fuel From Sunlight

New solar fuel machine 'mimics plant life'

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.

As described in an article in Clean Energy Authority.com, the device consists of a quartz lens that focuses the solar radiation on a reaction chamber that is internally reflective and captures most of the photons that enter and converts them to heat. The device heats up at a rate of 140 degrees Celsius a minute until it reaches about 1,250 degrees Celsius, and stabilizing at more than 1,400 degrees Celsius. Through a two-step process, the device’s catalyst ceria (cerium dioxide) converts CO2 or water into its constituent elements.

Haile said in an interview, “Ceria is a metal oxide, what that material will do when heated is it will release oxygen.…It happens at high temperatures, when we cool it back down it wants to absorb oxygen.  “The ceria replaces the oxygen by stripping it from the supplied material, carbon dioxide or water, thereby creating carbon monoxide—used for syngas, or hydrogen—which can be used directly. Either resulting fuel could be used to store the sun’s energy for use in power generation.”

Doped CeO2 with a low specific surface area is thermochemically cycled between MO2 and MO2−δ using H2O and CO2 as oxidants. The system rapidly and selectively produces syngas in the absence of a metal catalyst, and CH4 in the presence of Ni. [...]

Ethiopian Scientist develops reactor to make fuel from sunlight

“We have a big energy problem and we have to think big,” said Prof Sossina Haile, at the California Institute of Technology, who led the research.

Haile estimates that a rooftop reactor could produce about three gallons of fuel a day. She thinks transport fuels would be the first application of the reactor, if it goes on to commercial use. But she said an equally important use for the renewable fuels would be to store solar energy so it is available at times of peak demand, and overnight. She says the first improvements that will be made to the existing reactor will be to improve the insulation to help stop heat loss, a simple move that she expects to treble the current efficiency.

The key component is made from the metal cerium, which is almost as abundant as copper, unlike other rare and expensive metals frequently used as catalysts, such as platinum. Therefore, said Haile, availability would not limit the use of the device. “There is nothing cost prohibitive in our set-up,” she said. “And there is plenty of cerium for this technology to make a major contribution to global gasoline supplies.”