Light emitting diodes (LEDs) are solid-state lighting components.
They have no moving, fragile parts and can last for decades.
LEDs can be many times more energy efficient than light bulbs,
depending on the application. Just as vacuum tubes in televisions
were replaced with solid-state components, the last remaining
vacuum tube light bulbs are being replaced by solid-state components.
Imagine a grain of sand that emits a very bright light, usually
red, amber, green or blue, depending on the material, when
an electrical current is applied. That's essentially an LED.
The actual science and manufacturing process to develop an
LED is quite complex, but the principle is simple.
The first LEDs for commercial applications were red. They
functioned as on/off or indicator lights in electronic devices
such as VCRs, calculators, stereo systems and even automobile
subsystems. Eventually, LEDs were produced in green and amber
as well. The major breakthrough came in 1989 when Cree, Inc.
of Durham, NC, started shipping the first commercially viable
blue LED, based on silicon carbide. That blue LED enabled white
LED-based light. Mixing red, blue and green light produces
white light.
Today, a more-efficient and cost-effective white LED light
is revolutionizing the lighting world. The white power LED,
based on a blue LED chip coated with a phosphor, is bright
and efficient enough to be used in general illumination. Fixture
manufacturers are making LED-based products for outdoor street,
walkway, parking and indoor-down light applications.
Cree, a company whose founders included
several N.C. State University graduate students, introduced
the first lighting-class white power LED in 2006 and followed
up with the first lighting-class warm (softer) white power
LED in early 2007. LEDs are ready for general-illumination
applications, presenting a dramatically enhanced lighting option
to save energy and maintenance costs as well eliminate the
hazardous-waste issues associated with mercury-containing light
bulbs and tubes.
The history of man-made light
is based on heat. Wax, oil and gas burn to produce light.
The filament in an incandescent bulb heats up to produce
light. Gas in a fluorescent tube is zapped to illuminate.
The basic method is "Heat it up,
and it glows."
For more than 120 years, incandescent light bulbs have brightened
and literally warmed our lives. Electric-powered bulbs were
a major improvement over candle, gas and oil light sources,
but they are extremely inefficient. Bulb-based light sources
are far better at producing heat than light – up to 90 percent
of the power going into a bulb is converted to heat.
Compact fluorescent bulbs (CFLs) are more efficient, and
are an excellent alternative to incandescent bulbs for Edison-socket
light fixtures. However, they contain a small amount of mercury,
making them hazardous waste when they break or burn out.
In the past 12 months, a new light source has emerged that
is sufficiently bright and efficient to be used for general
illumination. The light emitting diode, commonly called the
LED, uses far less energy and can last many times longer than
most bulbs and contains no lead or mercury. Cree, Inc. introduced
the first commercially available lighting-class LED in late
2006. Lighting manufacturers are now producing a whole new
class of LED lighting products for general illumination.
LEDs are now ready for broad deployment
across general lighting applications such as parking garages
and lots, streetlights and other outdoor installations. Indoor
directional and down light solutions are also becoming available. According
to the University of California, Santa Barbara, widespread
deployment of LED-based lighting could save $115 billion in
electricity costs in the U.S. alone by 2025.
By committing to LEDs in campus lighting,
universites are making a thoughtful energy choice that will
greatly benefit their students, teachers, staff and the environment.
Want to learn more about how LEDs work? Try these resources:
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According to the U.S. Department
of Energy, in the next 20 years, rapid adoption of LED lighting
in the U.S. can:
— Reduce electricity demands
from lighting by one-third
— Eliminate 258
million metric tons of carbon emissions
— Avoid
building 40 new power plants
— Create financial savings that could exceed $200 billion |
