At first, the title of this chapter may appear a bit odd for as you already know, light-emitting diodes (LEDs) emit light. However, instead of completely focusing on the manner in which LEDs emit light, this chapter will primarily focus on their use in lighting applications. Such applications range the gamut from the use of LEDs in flashlights and backlighting liquid-crystal displays (LCDs) to the introduction of LED-based lightbulbs that can be expected to eventually replace fluorescents in a manner similar to how fluorescent lightbulbs are now replacing filament-based lightbulbs.

In this chapter, we will primarily focus our attention on the use of LEDs to provide an alternative to conventional filament-based lighting as well as the more modern fluorescent lighting. In doing so, we will first discuss the rationale for the replacement of filament-based lightbulbs that, as strange as it might seem, is not based on economics, which consumers tend to ignore, but primarily on congressional mandate and utility subsidization of the cost of compact fluorescent lightbulbs. Once we obtain an appreciation for the utility industry subsidization of compact fluorescent lightbulbs and the congressional mandate for replacing filament-based lightbulbs, we will briefly examine the economics associated with their replacement. In doing so, we will not only examine the cost of operating filament-based, fluorescent, and LED bulbs, but in addition look at their life cycle cost.

In the second section of this chapter, we will turn our attention to the LED-based lightbulb. We will describe and discuss a relatively new type...