Solar lasers not just for James Bond villains

Harnessing the sun's rays to produce a beam of pure energy has long been the goal of inventors from the ancient Greek engineer Archimedes (focused mirrors to destroy invading ships) to James Bond villains (space-based lasers of "Diamonds are Forever" and "Die Another Day").

But new research may realize the dream for a more down-to-Earth use: renewable energy.

A researcher in Uzbekistan has proposed a plan using small parabolic mirrors about 3 feet in diameter, combined with new two-layer ceramic disks to produce laser light.

"It is possible to make solar-powered lasers with the efficiency of 30 to 40 percent," said Shermakhamat Payziyev, a researcher at the Scientific and Production Association "Akadempribor" in Tashkent.

Payziyet said his proposal is a step beyond a similar project unveiled by Japanese researchers in 2007 which used a glass Fresnel lens instead of mirrors to create a laser to combust magnesium found in seawater.

Payziyet says his plan, published this month in the Journal of Renewable and Sustainable Energy, would use the sun's energy to create a laser to power electric cells.

"We proposed an idea how to convert effectively the solar light into the laser," Payziyet said. "In principle it can be converted into electricity by using concentrating photovoltaic modules with the efficiency of about 50 percent or closer to 100 percent in the near future."

Solar-powered lasers already exist on an experimental basis. But there have always been two major issues: removing the heat generated by the mirrors and the converting one kind of power to another efficiently.

Payziyet's unit tackles both.

When sunlight hits the ceramic material, it excites the electrons and causes them to emit laser light of a specific wavelength. To control the heat, the ceramic disk would be mounted atop a heat sink through which water would be pumped. The laser light would then take another reflective bounce through the ceramic surface, which produces an extra amount of efficiency, Payziyet said.

Sounds cool, but the project does have some doubters.

Eli Yablonovich, professor of electrical engineering and computer sciences at the University of California at Berkeley and director of the NSF's Center for Energy Efficient Electronics Science, wrote a paper about unfocused solar powered lasers back in 1983. He says focused lasers haven't really worked out.

"They don't solve any useful problems," Yablonovich in an email. Laser energy from the sun "can be directed into a solar cell, but the added complexity is not worth it."

Yablonovich believes that advanced solar collectors are a better bang for the energy-collecting buck and co-founded Alta Devices, a Silicon Valley firm which is making high-efficiency photovoltaic solar cells.

Despite the obstacles, Payziyet says his proposed solar-powered laser will get off the ground. He says it can be used to synthesize industrial quantities of nano-particles and nano-powders used to manufacture composite materials, superconductors, solar batteries and advanced paints or coatings.

He works at the site of the world's largest solar furnace, known as the Big Solar Furnace in Uzbekistan. It sounds like a bad guy's lair, but Payziyev says he's no Bond villain out to create a death ray.

"It is obvious that any new idea will be considered regarding its use in military purposes at first, but I am not supporter of this bad idea," he said. "The solar laser is a promising way in the use of renewable energy as an ultimate energy source for peaceful purposes."

? 2011 Discovery Channel

Source: http://www.msnbc.msn.com/id/44581819/ns/technology_and_science-innovation/

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