Renowned Astronomer Refocusing From Arizona’s Night Skies to Solar Energy

Posted By Mike Padgett

June 25, 2009

TUCSON, Ariz. – A world-famous University of Arizona astronomer is shifting his focus from the faintest stars in the night sky to the brightest daylight star at the center of the solar system.

Roger Angel and other researchers at UA and at Arizona State University hope to harness energy from the sun. They are collaborating on a new design of reflectors for next-generation solar energy generating systems.

“The possibility is, you may be able to combine reflector-concentrating solar ideas and photovoltaic technology and try to get the best of both of them and make something that’s lower cost than either of them,” Angel says, “and that’s the direction that I’ve been looking at.”

Unlike oil and coal, sunlight is available worldwide, especially during summer months. “Solar is free,” Angel says. “It just arrives free every day. So we have to be smart enough (to create solar energy).”

He leads me across the hall from his UA office to a lab. There, he picks up a small photovoltaic cell. It’s about 1.5 centimeters across. The goal is to use the tiny cells and curved mirrors to concentrate sunlight to create solar energy.

“We make the biggest mirrors in the world for astronomical telescopes, so why not make mirrors for solar concentrators,” he says.

Angel and his team at the UA Steward Observatory Mirror Laboratory design and build large telescopes. They create telescope mirrors as large as 26 feet in diameter. Angel is founder and director of the Steward mirror lab.

The photovoltaic cells commonly used in solar panels have an efficiency range of less than 20 percent. That range could be doubled if sunlight could be concentrated onto the cells, such as by using curved mirrors, Angel says.

“Mirror technology may be a key to making low-cost solar energy,” he says. “As you know, solar can be very expensive if you don’t subsidize it. So in order to do anything useful for global warming, you’ve got to make solar energy less expensive.

“If you can figure out how to make mirrors and point them at the sun and focus light onto these (high-efficiency photovoltaic) cells, if you can do that inexpensively, then you can make electricity inexpensively.”

Angel reveals few other details of his proposal. He says “about 20 startup companies in the U.S. are trying to figure out how to focus light on these cells inexpensively.”

In May, Angel filed for patents for his concept. Although he’s keeping quiet about details, “there will be a time when all of this – for better or worse, I wrote up in 100 pages the complete recipe for what I think is the right system – will be published, since the patent office publishes stuff.”

The UA-ASU team received a $2 million grant as part of the Solar Technology Institute announced in April by Science Foundation Arizona. Co-directors of STI are solar-energy pioneers Richard Powell and Robert Annan. Assisting in the financial support of the SFAz grants is Stardust Foundation.

Angel, 67, grew up near London. He received his doctorate from Oxford University in 1967. His bachelor’s and master’s degrees are from the California Institute of Technology. He taught for six years at Columbia University before joining the UA in 1974.

He is a member of many scientific organizations. They include the National Academy of Sciences, the American Academy of Arts and Sciences, a Fellow of the Royal Society, a Fellow of the Royal Astronomical Society, an Honorary Fellow of St. Peter’s College, Oxford, and a MacArthur Fellow.

Angel’s many awards include one from the American Astronomical Society in 2006. In 2007, the Optical Society of America honored him with the Fraunhofer/Burley Prize “for innovation in optical systems development, including large astronomical telescope and mirror technology, methods for observing extra-solar planets, fiber-fed spectroscopy, adaptive optics, and a possible optical solution for global warming,” according to a UA press release.

During the interview, Angel referred to a thought-provoking quote attributed to Thomas Edison, reportedly in a 1931 conversation with automaker Henry Ford and tire manufacturer Harvey Firestone. Edison said: “I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that. I wish I had more years left.”

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Jun 25th, 2009

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