Restructered pre-import

Old Pages/Electronics/LED_streetlights.md

@@ -0,0 +1,70 @@
+# Efficiency
+
+Interesting factoids about [replacing sodium vapor lamps with
+LEDs](http://dansdata.blogsome.com/2008/12/27/led-street-lighting-not-as-good-as-you-think/)
+for city-wide lighting.
+
+- The theoretical lumen/Watt figures for LEDs are worse than
+  low-pressure sodium vapor lamps (100 lm/W versus 200 lm/W)
+- White LEDs are actually blue LEDs with a consumable phosphor layer
+  that turns opaque after a few years of operation.
+- Combined RGB LEDs will have better efficiency than a "white" LED.
+
+Other real-world tests have concluded that LED street lights have about
+the same lumen/Watt in practice as the sodium vapor lamps ([64 lm/W
+LEDs](http://www.olino.org/us/articles/2008/11/02/streetlamp-lioris-aduro-52)
+versus [67 lm/W Sodium
+vapor](http://www.olino.org/us/articles/2008/12/29/indal-industria-aurora-streetlamp)).
+
+Neon and florescent efficiency [depends on the color and
+shape](http://www.signindustry.com/neon/articles/2003-07-11-RC-NeonandFlour.php3):
+
+> \[...\] the fluorescent tube produces between 50 and 100 lumens of
+> light per watt depending upon design. Compare this with the typical
+> incandescent light bulb that produces between 10 and 20 lumens per
+> watt. Neon light efficiency is based upon much fancier pants, the
+> color of its output, which ranges from 10 lumens per watt for red to
+> 60 lumens per watt for green or blue. One reason that green and blue
+> tubes are more efficient is that phosphor coatings used to produce
+> such colors better ballyhoo the high-energy ultraviolet light from the
+> argon/mercury mix into visible colors. One reason that the fluorescent
+> tube is more efficient than a neon tube is that a large straight tube
+> offers less resistance to electrical current flow than a skinny bent
+> one.
+
+# Obstacles
+
+Little Rock, AK wanted to replace their inefficient shielded lights with
+more efficient fixtures, but their contract with Entergy is not a simple
+\$/kW formula: [the energy company sets the price based on the type of
+fixture](http://www.arktimes.com/Articles/ArticleViewer.aspx?ArticleID=fce07cab-0dea-4fc5-b57e-f1145715f01e).
+
+> \[...\] According to Henry, the city tested out more efficient
+> 100???watt HPS bulbs in one Little Rock neighborhood about five years
+> ago. When the city asked Entergy to set a rate for those fixtures, it
+> was almost double the rate for the 150-watt HPS type.
+>
+> When asked if Entergy was keeping Little Rock from being more energy
+> efficient, Henry said simply, "Yes."
+>
+> "But how do you fight Entergy?" Henry asked. "I mean, we've had people
+> come in and show us new, more efficient lights and we've said, well,
+> the problem is, it's not going to save us anything. It will be a whole
+> lot less wattage and it will put light out on the street but we can't
+> get any benefit out of it because of the tariffs."
+
+# Commercial LED lamps
+
+[SparkFun](http://sparkfun.com) sells LED lamps that are screw
+compatible with US light sockets:
+
+- [75
+  W](http://www.sparkfun.com/commerce/product_info.php?products_id=8716)
+- [12
+  W](http://www.sparkfun.com/commerce/product_info.php?products_id=8714)
+- [3
+  W](http://www.sparkfun.com/commerce/product_info.php?products_id=8717)
+- [1
+  W](http://www.sparkfun.com/commerce/product_info.php?products_id=8715)
+
+[Category:Useful_Info](Category:Useful_Info "wikilink")