We should thank the city of Santa Maria and the county of Santa Barbara for the “alien microwave orange” street lights (“Turn. Out. Those. Lights.” Sept. 30). They are both using the most energy-efficient type of lamps there are.
Luminous efficacy gives a relative efficiency for all kinds of lamps. The orange sodium discharge lamps give 22 percent for low pressure and 29 percent for high pressure; compare this with 2 percent for a regular tungsten bulb, 3.5 percent for tungsten halogen, and 15 percent for fluorescent tubes. LEDs (light emitting diodes) show promise (theoretical limit is 44 percent), but current technology only gives 20 percent; they are also only available in low-power outputs due to heat limits for this type of device.
Using sodium discharge lamps also means fewer light poles (there are mandates on lighting levels on certain streets) and less maintenance than other lamp types. The light they give also penetrates our marine layer better.
Technology has come a long way from luminous efficiency of a candle of 0.04 percent and a gas mantle of 0.3 percent.
So again, thanks for saving taxpayer dollars on your choice of street lighting.