Chief among the advantages of LEDs is that they have extremely long lives -- they don't have filaments that can quickly burn out -- and they don't contain toxic chemicals like mercury, unlike traditional high-pressure sodium lamps or mercury-vapor lamps. An LED light can last 100,000 hours [source: Rosenthal and Barringer]. These lights also have reduced maintenance costs because of their long lives, and they give off less heat than other bulbs. Because they last so long, LEDs are suitable for places where replacing light bulbs is expensive, inconvenient or otherwise difficult.
LEDs are highly energy efficient. While compact fluorescent lamps (CFLs) recently have been touted as the standard in green lighting, LEDs actually have double their energy efficiency [source: Rosenthal and Barringer]. They use 15 percent of the energy of an incandescent bulb while generating more light per watt [source: Taub]. LEDs produce 80 lumens per watt; traditional streetlights can only muster 58 lumens per watt [source: Bailey].
Because of their energy efficiency and long lifespan, LED streetlights are advocated as a means for reducing carbon emissions. According to one estimate, converting all American light fixtures to LEDs would halve the amount of energy used for lighting in the country [source: Rosenthal and Barringer]. By integrating solar panels, the lights can become self-sufficient and even send excess energy back to the grid, with the adoption of so-called "smart" energy grids.
So what else do these lights have going for them? For one, there's no warm up needed -- they're quick to turn on. They don't produce ultraviolet light, which is what attracts bugs.
Because they produce "directional" light -- light emitted in one direction, rather than a diffused glow -- they can be used to direct light on specific areas. Unlike compact fluorescent lamps, they can be dimmed, allowing for more flexibility in controlling light levels. Some cities have harnessed LED lights to create clever effects, such as increasing in brightness when a pedestrian walks by or integrating systems that alert officials when a particular light needs maintenance. They can also be used to blink rapidly to signal to emergency responders where they are needed.