Resource World Magazine

A LTER NAT I V E E N E R G Y R EV IEW Developments in Alternative Energy APPLE'S NEW CAMPUS FEATURES SOLAR PANELS The Cupertino, California city council has granted final approval to Apple, Inc. [AAPL-NASDAQ] to begin construction of a new, 176-acre corporate headquarters. The Apple Campus 2 will feature the largest solar panel array in the US dedicated to a single corporate campus, and is among the largest in the world. The campus will be a massive, circular building, 1,200 feet in diameter, providing approximately 2.8 million square feet of office space. That translates to more than 750,000 square feet of space on the building's roof, nearly all of which will be solar panels. With on-site fuel cells and use of grid-purchased renewable energy during peak hours, Apple says that its new campus will be powered 100% by renewable energy and will not result in any net additional greenhouse gas emissions. The construction project, including the introduction of the photovoltaic panels, will also add approximately 7,400 jobs to the city of Cupertino. RESEARCHERS USE NATURAL SUNLIGHT TO ILLUMINATE BUILDINGS According to the University of Cincinnati, Ohio's newsletter, researchers using tiny electrofluidic cells and a series of open-air "ducts," are capturing sunlight to naturally light windowless work spaces deep inside office buildings and store excess energy or direct it to other applications. This method, called SmartLight, is more efficient than converting light into electricity then back into light and will be more sustainable than generating electric light by burning fossil fuels or releasing nuclear energy. The technology could be applied to any building but researchers believe it will have the greatest 58 www.resourceworld.com RW December 2013.indd 58 effect on large commercial buildings. SmartLight works by taking a narrow grid of electrofluidic cells, which is selfpowered by embedded photovoltaics, and applying it near the top of a window. Each tiny cell, only a few millimetres wide, contains fluid with optical properties as good as or better than glass. The grid might direct some light to reflect off the ceiling to provide ambient room lighting. Other light might be focused toward special fixtures for task lighting. Yet another portion of light might be transmitted across the empty, uppermost spaces in a room to an existing or newly installed transom window fitted with its own electrofluidic grid. From there, the process could be repeated to enable sunlight to reach the deepest, most light-locked areas of any building. And it's all done without needing to install new wiring, ducts, tubes or cables. Plans call for SmartLight to be controlled wirelessly by a mobile software application. So instead of manually flipping a switch on a wall, users would select their lighting preferences through an application on their mobile device, and SmartLight would regulate the room's brightness accordingly. SmartLight could even use geolocation data from the application to respond when users enter or leave a room or when they change seats within the room by manipulating Wi-Fi-enabled light fixtures. At night or on cloudy days, SmartLight's energy storage ability takes over. On a typical sunny day, sunlight strikes a facade at a rate that's often hundreds of times greater than needed to light the building. SmartLight can funnel surplus light into a centralized harvesting and energy-storing hub within the building. The stored energy could then be used to beam electrical lighting back through the building when natural by Jane Bratun light levels are low. The SmartLight's grid is so responsive – each cell can switch by the second – it can react dynamically to varying light levels throughout the day or night. With such potential for energy storage, a building's electrical network also could tap into the centralized hub and use the stockpiled energy to power other needs, such as heating and cooling. And if centralized collection of surplus sunlight isn't possible inside some existing structures, the light could even be sent straight through a building to a neighboring collection facility. Scientists say much of the science and technology required to make the SmartLight commercially viable already exists. They have begun evaluating materials and advanced manufacturing methods. LITHIUM-SULPHUR BATTERIES COULD PROVIDE 300-MILE ELECTRIC VEHICLE RANGE Researchers at the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) in California have demonstrated, in the laboratory, a lithiumsulfur (Li/S) battery that has more than twice the specific energy of lithium-ion batteries and lasts for more than 1,500 cycles of charge-discharge with minimal decay of the battery's capacity. This is longest cycle life reported so far for any lithium-sulfur battery. For electric vehicles, to have a 300-mile range, the battery should provide a cell-level specific energy of 350 to 400 Watt-hours/ kilogram (Wh/kg). This would require almost double the specific energy (about 200 Wh/kg) of current lithium-ion batteries. The batteries would also need to have at least 1,000, and preferably 1,500 charge-discharge cycles without showing a noticeable power or energy storage capacity loss. "Our cells may provide a substantial DECEMBER/JANUARY 2014 12/11/2013 6:12 PM

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