Resource World Magazine

little bigger than a typical Toronto Hydro transformer and enables stable solar and wind energy supplies. RESEARCHERS DEVELOP A NEW WAY OF MAKING CRYSTALLINE SILICON A new way of making crystalline silicon, developed by researchers at the University of Michigan at Ann Arbor, could make developing this crucial computer and solar cell ingredient much cheaper and greener. Silicon dioxide (sand) makes up about 40% of the earth's crust, but the industrial method for converting sand into crystalline silicon is expensive and has a major environmental impact due to the extreme processing conditions. "The crystalline silicon in modern electronics is currently made through a series of energy-intensive chemical reactions with temperatures in excess of 2,000 degrees Fahrenheit; that produces a lot of carbon dioxide," said Stephen Maldonado, professor of chemistry and applied physics. Recently, Maldonado and chemistry graduate students discovered a way to make silicon crystals directly at just 180° F, the internal temperature of a cooked turkey. They did it by taking advantage of a phenomenon you can see right in your kitchen. When water is super-saturated with sugar, that sugar can spontaneously form crystals, popularly known as rock candy. "Instead of water, we're using liquid metal, and instead of sugar, we're using silicon," Maldonado said. Maldonado and colleagues made a solution containing silicon tetrachloride and layered it over a liquid gallium electrode. Electrons from the metal converted the silicon tetrachloride into raw silicon, which then dissolved into the liquid metal. "The liquid metal is the key aspect of our process," Maldonado said. "Many solid metals can also deliver electrons that transform silicon tetrachloride into disorAPRIL 2013 dered silicon, but only metals like gallium can additionally serve as liquids for silicon crystallization without additional heat." The researchers reported dark films of silicon crystals accumulating on the surfaces of their liquid gallium electrodes. So far, the crystals are very small, about 1/2000th of a millimetre in diameter, but Maldonado hopes to improve the technique and make larger silicon crystals, tailored for applications such as converting light energy to electricity or storing energy. The team is exploring several variations on the process, including the use of other low-melting-point metal alloys. Crystalline silicon is the most-used solar energy material, but the cost of silicon has driven many researchers to actively seek alternative semiconductors. "It's too premature to estimate precisely how much the process could lower the price of silicon, but the potential for a scalable, dramatically less expensive and more environmentally benign process is there," Maldonado said. "The dream ultimately is to go from sand to crystalline silicon in one step. There's no fundamental law that says this can't be done." THE WEST COAST ELECTRIC HIGHWAY POWERS ELECTRIC VEHICLES FROM BRITISH COLUMBIA TO CALIFORNIA The West Coast Electric Highway connects British Columbia to Baja, California. When fully completed, the highway will span 1,300 miles. The highway provides an extensive network of electric vehicle (EV) DC fast-charging stations located along Interstate 5 and other major roadways. The Electric Highway gives electric vehicle drivers the "range confidence" that recharging is available should they want to travel between communities or make long distance road trips. Knowing that charging is easy and convenient helps encourage residents and businesses to buy and drive plug-in electric vehicles. Increasing the market demand for electric vehicles helps reduce the transportation sector's impact upon the environment and dependency on foreign oil. By setting the stage for the EV industry to thrive in a clean economy, the Electric Highway helps spur industry growth and new jobs. The five latest charging stations added to the Highway were installed as part of a pilot program led by Portland General Electric (PGE) in an effort to complete the highway in Oregon, and used Blink DC Fast Chargers manufactured by ECOtality [ECTYNASDAQ]. "Through the EV Highway pilot, PGE is working with our customers along the interstates who want to host charging stations and charging station manufacturers that want to install them," said Kurt Miller, PGE's director of business model and program development. "These two new stations close the gap between quick-charge stations along the interstate system making the West Coast Green Highway a reality in Oregon." "We are very excited to be partnering with PGE in completing this stretch of the I-5 corridor," said Amy Hillman, ECOtality area manager. "Completing this project is yet another step forward, boosting drivers' range confidence and enabling them to use their EV as their primary vehicle, while providing them with the benefits of fast charging that more closely reflects their lifestyle." n www.resourceworld.com 59

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