Musicmystery
Posts: 30259
Joined: 3/14/2005
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You are SO missing the point. The cost of lighting a bulb far outstrips its cost.
Consider a larger scale:
http://www.ledsmagazine.com/news/4/8/16
Currently, the City incurs $372,000 in annual electricity costs for street lighting, and this could be reduced by 47% if all the fixtures are replaced with LEDs. Along with a further projected 75% reduction in $179,000 of annual capital and maintenance costs, the City could realize $309,090 in annual savings.
"Congratulations to Welland for leading the way with its pilot project to install LED street lighting,
More energy-efficient light-emitting diodes are rapidly becoming the preferred lighting solution worldwide
By David Biello |
http://www.scientificamerican.com/article.cfm?id=led-there-be-light
torraca-LEDs FIRST LED CITY: Torraca, Italy, is the first town to be entirely lit by LED lights. Image: COURTESY OF CREE
Torraca is a small village of 1,200 people in Italy. It is also the first place in the world to be totally illuminated by light-emitting diodes (LEDs). Representing a sea change, much like when electric lamps first graced London's Holborn Viaduct back in 1878, some 700 streetlights (each containing 54 LEDS) now line Torraca's arteries—and locales around the world, from Beijing's Bird's Nest Olympic Stadium to the Raleigh Convention Center's Shimmer Wall in North Carolina, have begun to use LEDs to light up the night.
"There are more than 30 installations like Torraca around the world," says Mark McClear, director of business development at Durham, N.C.-based LED-maker Cree, Inc., which made the LEDs in Torraca's streetlamps. "It's growing weekly."
The lightbulb of the future may just be a small piece of semiconductor. Rather than heating tungsten to at least 3,100 degrees Fahrenheit (1,700 degrees Celsius) or exciting fluorescent gases, LEDs can produce lumens with less electricity.
. . .
Cost has been the major obstacle for LEDs, which last up to as 50,000 hours (10 years if used 12 hours a day)—gradually dimming over time—compared with about 800 hours for a typical 100-watt incandescent. "The average bulb is on two hours a day. At that rate, an LED would last 136 years," McClear says. "If you bought a fixture and only used it two hours a day, it would last longer than your house. It would last longer than you."
Potential energy savings, however, appear to hold more sway with cities and building owners than cost. After all, some 22 percent of all electricity use in the U.S. is devoted to lighting, according to the U.S. Department of Energy—and switching to LEDs could save $280 billion by 2028. In fact, researchers at the Rensselaer Polytechnic Institute in Troy, N.Y., estimate that replacing incandescents with LEDs could save $1.83 trillion in energy costs globally over the next decade and eliminate the need for 280 1,000-megawatt power plants.
"Forcing electricity though a filament and heating it up to the point where it emits light, [is] horribly inefficient, on the order of 95 percent inefficient," McClear says. "The best LEDs are on the order of 35 percent more efficient."
Among those dazzled by LEDs: North Carolina State University in Raleigh, which last year installed 730 Cree LED lights in a dormitory building and saved 44 percent of the energy consumed by the fluorescent predecessors per day, according to the university. Discount chain Wal-Mart has replaced fluorescent light fixtures in its freezer sections with LEDs. And the City of Los Angeles plans to replace some 140,000 street lamps with LED fixtures by 2014 at a cost of $57 million, tapping some of its funding from the Clinton Climate Initiative and the Los Angeles Department of Water & Power.
New LED lights can put out the equivalent light of 100-watt incandescent while only consuming 13 watts of power. They also outlast equivalent compact fluorescent lightbulbs but use 50 percent less energy and skip the toxic mercury required as ballast. The U.S. Environmental Protection Agency (EPA) estimates that 670 million such fluorescent lights end up in the trash yearly and release some two to four tons of mercury per annum into the environment.
Advances in the underlying technology have allowed Cree, for one, to boost output from a single one-square-millimeter diode to 161 lumens per watt. Partially as a result, the Federal Reserve is using LEDs for its overhead recessed lights and the Pentagon has installed some 4,200 LED fixtures to reduce energy costs and improve light quality, according to the U.S. Department of Defense.
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