15 September 2011

The LED Light Bulb

As of 2010, only a few LED light bulb options are available as replacements for the ordinary household incandescent or compact fluorescent light bulb. One drawback of the existing LED bulbs is that they offer limited brightness, with the brightest bulbs equivalent to a 45-60 W incandescent bulb. Most LED bulbs are not able to be dimmed, and their brightness retains some directionality. The bulbs are also expensive, costing $40–50 per bulb, whereas the ordinary incandescent bulb costs less than a dollar. However, these bulbs are slightly more power efficient than the compact fluorescent bulbs and offer extraordinary lifespans of 30,000 or more hours.

An LED light bulb can be expected to last 25–30 years under normal use. LED bulbs will not dim over time and they are mercury free, unlike the compact fluorescent bulbs. Recent research has made bulbs available with a variety of color characteristics, much like the incandescent bulb. With the savings in energy and maintenance costs, these bulbs can be attractive. It is expected that with additional development and growing popularity, the cost of these bulbs will eventually decline


Fluorescent tubes with modern electronic ballasts commonly average 50 to 67 lumens/W overall. Most compact fluorescents rated at 13 W or more with integral electronic ballasts achieve about 60 lumens/W, comparable to the LED bulb. A 60 W incandescent bulb offers about 850 lumens, or 14 lumens/W.

Several companies offer LED lamps for general lighting purposes. The C. Crane Company has a product called "Geobulb". The GeoBulb II uses only 7.5 W (59 lumens/W).In October 2009, the GeoBulb II was superseded by the GeoBulb-3 which is brighter and longer lasting.The company also offers wedge-base lamps for replacement in low voltage fixtures. In the Netherlands, a company called Lemnis Lighting offers a dimmable LED lamp called Pharox.The company Eternleds Inc. offers a bulb called HydraLux-4 which uses liquid cooling of the LED chips.