New machine simulates the sunlight of more than 3,000 suns

University researchers are using the solar simulator to make synthetic hydrocarbon fuels.
December 10, 2010

The sun went down in Minneapolis at 4:30 Thursday, but in the mechanical engineering building, University of Minnesota researchers can reproduce the light of more than 3,000 suns.

There, they’re using a new high-tech concentrated solar simulator to develop ways of converting carbon dioxide and water into solar fuels.

In their setup, some 6,500 bulbs in an array of seven mirrored lamps focus their light on a single spot about 3 inches in diameter.

Jane Davidson, director of the Solar Energy Laboratory and lead researcher, said a sponge-like material called cerium-oxide, developed by chemists at CalTech, is placed in the reactor. When it’s heated up using concentrated sunlight, it releases oxygen. The cerium-oxide is then brought to a lower temperature so they can pass water through the material to create hydrogen, the basis for synthetic gas. Once the machine is heated up, fuels are continually produced.

There are advantages to using this technology to create synth-gas, Davidson said. It’s sustainable, faster and more efficient than producing petroleum.

Wojciech Lipinski, another research in the lab, said there were also no byproducts because the amount of oxygen released during the process was the exact same amount used during the combustion of fuel.

The hydrocarbon fuels would be available the same as petroleum based fuels are today, but they’d be made in the United States.

 “In southwestern states like Arizona and California, you have more than 350 sunny days throughout the year,” Lipinski said.

Davidson estimated that it would take 15 million acres of land (roughly the size of West Virginia) with solar plants to create enough solar fuel to replace petroleum.

The sunlight simulator will be used to create a prototype for use in the real world using real sunlight, but Davidson said it will be two years before they’re ready for that stage. But by using a sunlight simulator, they increase the amount of time they can spend researching, especially in a state like Minnesota where there aren’t as many sunny days.

The simulator was designed by Katie Krueger, a mechanical engineering graduate student.

While the equipment cost $450,000 to make, the rest of their work will be covered by a nearly $1 million National Science Foundation grant and $1.4 million in research grants for the Solar Energy Laboratory from the University’s Institute on the Environment.

About 16 graduate students in mechanical engineering, chemistry and bioproducts and biosystems engineering programs have the opportunity to work with the simulator.

Temperatures in the reactor get very high, exceeding 3,600 degrees Fahrenheit, high enough to burn through steel. For the most part, researchers monitor the simulator from a computer in another room. Davidson said if they have to repair the machine they wear weldering masks and other protective gear.

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