Trippy idea
Bright lights, big energy
Hybrid solar lighting: a solar retrofit for hot climates
Posted by Gar Lipow (Guest Contributor) at 2:08 PM on 03 Jun 2008
A fascinating commercial application for solar energy in clear (or semi-clear) hot climates seems to not be getting the attention it deserves: hybrid solar lighting.
You take a parabolic concentrator and focus some sunlight, optically split with plastic fiber into visible light and heat. Pipe the visible light through diffusers throughout the building. It saves lighting electricity, of course, but unlike skylights or conventional T8s, it adds almost no heat to the building. In a cooling climate it saves about a third as much in air-conditioning energy as it does in light.
You still need electric lighting supplementation, but in office buildings you get most of the light when you need it. And the advanced diffusers means you have only one hole to cut into the building. That gets you better odds of decent installation that avoids leaks or thermal bridges.
Unlike solar PV, which typically turns 15 percent of sunlight into electricity, this system saves the energy equivalent of about 50 percent of the energy striking the collector. Solar heating can do better, of course, but in cooling climates you don't have much call for that, and hot water demand is a much smaller percentage of total demand in office buildings than in residential ones. Originally the intent was to convert the other 50 percent of energy not used for lighting into electricity. Apparently the added capital costs were too high for deployment in actual commercial use.
gristmill.grist.org
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Hybrid solar lighting earns national technology transfer award
ORNL Engineer Dave Beshears displays the hybrid lighting system.
OAK RIDGE, Tenn., June 1, 2007 — An Oak Ridge National Laboratory-developed technology collecting sunlight connected to special indoor light fixtures has earned an Excellence in Technology Transfer Award from the Federal Laboratory Consortium for Technology Transfer.
The award was presented recently to representatives of the Department of Energy's Oak Ridge National Laboratory during the consortium's annual convention in Arlington, Texas.
The consortium is composed of more than 700 federal laboratories and facilities representing approximately 100,000 scientists and engineers. The awards recognize federal laboratory employees for outstanding work in the process of transferring a technology to the commercial marketplace.
The hybrid lighting technology uses a rooftop-mounted 48-inch diameter collector and secondary mirror that track the sun throughout the day. The collector system focuses the sunlight into 127 optical fibers connected to special light fixtures equipped with diffusion rods similar to fluorescent light bulbs. The rods spread light in all directions.
One collector currently powers eight to 10 hybrid light fixtures that can illuminate about 1,000 square feet of space. During times of little or no sunlight, a sensor controls the intensity of fluorescent lamps to maintain a constant level of illumination.
The technology reduces energy usage not only for lighting, but also for cooling due to the system's ability to block ultraviolet and infrared heat. The technology -- earning an R&D 100 Award and a Southeast Region Federal Laboratory Consortium Award during 2006 - could be particularly valuable in achieving improved energy efficiency in locations where there is an abundance of sunlight.
The system is estimated to save about 6,000 kilowatt hours per year in lighting and another 2,000 kilowatt hours in reduced cooling needs for a total savings of 8,000 kilowatt hours per year.
Hybrid lighting systems are being tested in various demonstration projects around the United States, including a Wal-Mart in McKinney, Texas, a Staples in Long Island, N.Y., a Braden's Furniture showroom in Knoxville, Tenn., The Naval Exchange in Hawaii, office space at San Diego State University, the Aveda corporate headquarters in Minneapolis and ORNL's Multi-Purpose Research Facility.
ORNL's hybrid lighting team is composed of David Beshears, Melissa Lapsa, Art Clemons, Dennis Earl, John Jordan, Randall Lind, Curt Maxey, Jeff Muhs, Christina Ward and Wes Wysor. The late Larry Dickens was ORNL's commercialization manager on the project.
The technology was developed through funding by DOE's Office of Energy Efficiency and Renewable Energy, Solar Technologies Program, along with a partnership of utility companies, state energy agencies, industry and universities.
ORNL is managed by UT-Battelle for the Department of Energy.
ornl.gov |
