LEDs 101

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 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.

Why LED City

Twenty percent of the world’s electricity is used for lighting. Ninety percent of the power used by a light bulb produces heat, not light. LEDs are more than four times more efficient than incandescent bulbs. And, they are more efficient than compact fluorescents (CFLs), the next most efficient light source available today. CFLs contain 5 milligrams of mercury, making them hazardous waste when they break or burn out.

Glass bulbs with filaments and glass tubes break – easily and often. Solid-state technology offers far more durability and much longer life times. LED fixtures can last 10-25 years, which can significantly reduce maintenance costs and impact on the environment.

LEDs offer the most efficient and environmentally friendly – no mercury or lead – lighting source.