International team of researchers from Mexico and Taiwan has come out with a new LED streetlight system which would greatly reduce light pollution and improve efficiency. The system is set up so that the high-efficiency LEDs only shine where they are needed.
With regards to the new lamp design, here are more details:
“[It's] based on a novel three-part lighting fixture. The first part contains a cluster of LEDs, each of which is fitted with a special lens, called a Total Internal Reflection (TIR) lens, that focuses the light so the rays are parallel to one another instead of intersecting — a process called collimation. These lens-covered LEDs are mounted inside a reflecting cavity, which ‘recycles’ the light and ensures that as much of it as possible is used to illuminate the target. Finally, as the light leaves the lamp it passes through a diffuser or filter that cuts down on unwanted glare. The combination of collimation and filtering also allows researchers to control the beam’s shape: the present design yields a rectangular light pattern ideally suited for street lighting.”
The performance of the system was quantified by the researchers using optical utilization factor (OUF) — a number that “describes the relationship between the flow rate of light at the target and the flow rate of light coming directly out of the LEDs.” The higher the OUF is, the better the performance. This new LED streetlight showed an OUF of 51% to 81%, a potentially huge improvement over other recent “excellent” designs, that achieved 45%.
In conventional streetlights, as high as a “20% of their total energy is directed horizontally or upward into the sky.” And even in the best LED streetlights, this number is still as high as 10%. But in the new design, only 2% of the streetlight's total energy is wasted as light pollution.
A general LED streetlight could reduce power consumption by 40% to 60%. The new LED streetlight could give additional 10% to 50% of energy-saving. Prototype of the design is expected within the next 3 to 6 months, according to the researchers. Installations of the new street lamp may begin as early as 2014.