Mrs. Jones contacted me today regarding the City of Mesa's LED street light test program.
I work in SRP's electric system engineering department and live in Marlborough Mesa.
The facts and fiction are as follows:
The city of Mesa and most other cities in the area use High Pressure Sodium (HPS) street lights. HPS lamps are the most energy efficient form of lighting for large scale application. That is the numbers of lumens of light created per watt of electricity consumed is very high. The downside to High Pressure Sodium is the color of the light they create is very monochromatic, or single color. This means that it is very difficult to distinguish the color of an object that is illuminated by HPS lighting. (there are no free lunches in engineering)
LED luminaires have come along way in the last several years and are still considered 'new technology'. Like all new technology they are also very expensive. The only way any city can afford to do large scale luminaire replacement is with government subsidies to offset the cost of the new technology.
LED street lights offer a couple key advantages over conventional HPS lights. Their color spectrum is significantly broader permitting the eye to distinguish the color of objects illuminated by them. Also by having hundreds of individual LEDs in a single luminare, each LED can be percisely aimed to more effectively cover a larger area. If you compare the light pattern from the new LED streetlight to a neighborhood with the older HPS lamps you will notice the HPS lamps create bright spots on the street directly under them while the LED street lights uniformly illuminate the area around them with fewer shadows.
As for the energy savings aspect, I have yet to see an LED streetlight that produces more lumens per watt than high pressure sodium technology. The LED streetlight experiments currently being conducted by SRP and APS have yet to show any significant reduction in energy consumption between LED streetlights and high pressure sodium.
Please note: there is a huge difference in energy consumption between incandescent bulbs and LED bulbs, so we could all benefit from switching to LED lighting in our homes.
So, while the jury is still out on the cost benefit of replacing our streetlights, We should all enjoy basking ourselves in the multi-chromatic, uniform glow of our cool new LED streetlights!
