Right now, consumers and businesses can buy a
light-emitting diode, or LED, that provides about the same
level of illumination as an
energy-hogging conventional 60-watt lightbulb, Steven
DenBaars, a professor of material science at the University
of California Santa Barbara,
said at the SEMI NanoForum, taking place here this week. A
principal advantage of the LED: It lasts about 100,000
hours, far longer than the
conventional filament bulb
Unfortunately, the LEDs that can perform this task cost
about $60, he said. (Prices vary on the Internet.) But
prices have been declining by 50
percent a year, so two years from now the same LED should
cost around $20.
"At $20 the payback in energy occurs in about a year,"
DenBaars said. The rapid return on investment will occur in
places such as stores and
warehouses, where the light is on through much of the day. A
year after that, LEDs will be even more economical for more
places as costs
continue to decline.
Approximately 22 percent of the electricity consumed in the
United States goes toward lighting, according to the U.S.
Department of Energy.
To make matters worse, traditional lightbulbs are incredibly
inefficient. Only about 5 percent of the energy that goes
into them turns into light.
The majority gets dissipated as heat.
If 25 percent of the lightbulbs in the U.S. were converted
to LEDs putting out 150 lumens per watt (higher than the
commercial standard now),
the U.S. as a whole could save $115 billion in utility
costs, cumulatively, by 2025, said DenBaars, and it would
alleviate the need to build 133 new
coal-burning power stations.
In turn, carbon emissions in the atmosphere would go down by
258 metric tons.
"Multiply that by three and you get the worldwide savings,"
he stated. DenBaars then showed a picture of the globe at
night. The landmass of the
U.S. could easily be picked out by nighttime lights.
"We shoot a lot of light into space that doesn't need to be
there," he noted.
Rising prices of electricity, combined with the antiquated
nature of lightbulb technology, has prompted several
start-ups and large industrial
concerns to get into lighting.
Fiberstars, for instance, has come up with a way to replace
hot fluorescent tube lights with light-emitting optical
fiber in freezer cases in
grocery stores. Hewlett-Packard spinoff Lumileds is also
producing LEDs for a variety of applications.
LED technology is improving as well. UCSB has created an
experimental LED that can put out 117 lumens per watt, while
a Japanese company has
developed one that can put out 130 lumens per watt.
Getting LEDs to produce white light that is tolerable to
humans has also greatly improved. Manufacturers can do it
two ways. One is to package
red, green and blue LEDs in a way that the combined light
shines white to the human eye. The other way is to make blue
LEDs and coat them with
a phosphor--a luminescent substance commonly used on
fluorescent lamps.
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