Seite - 47 - in Water, Energy, and Environment - A Primer

appliances. Their high switching rates are useful in advanced communications technology. LEDs havemany advantages over incandescent light sources including significantly lower energy consumption, much longer lifetimes, improved physical robustness, smaller size, and faster switching rates. While LED costs have come down rapidly, they do requiremore precise current and heatmanagement than compact fluorescent lamp sources of comparable light output. Their advantages overCFLs are greater efficacy (i.e.,more light output measured in lumens per watt), longer lifetimes, smaller size, directionality of the light produced, and, importantly, they contain nomercurywhichhas to bedisposed of.Deficiencies in these aspects severely limitedCFLs’market appeal. While LEDs are based on inorganic (non-carbon-based) materials, OLEDs are organic (carbon-based) solid-state light emitters which are made in sheets that provide a diffuse-area light source. They are still in an early stage of development and several years away from broad commercial application. Interesting potential applications include TV screens, computer and cell phone screens, wall coverings that allow changes in color, and automobile skins that allow you to change the color of your car. A simple calculation will help to demonstrate the cost effectiveness of the new lighting sources. They may be more expensive to buy than incandescent bulbs, but they save energy andmoney over extended lifetimes. It is also important to note that replacing bulbs less often also saves money by reducing labor costs. Iwill useLEDsasmyexample. I compare a 100W soft-white dimmable incandescent bulb with an equivalent light source, a soft-white dimmable 11W LED bulb, both selected from an online catalogue. The incandescent bulb is available at a cost of $1.08, while the LED bulb sells for $9.99; to simplify the calculations I will use $1 and $10 as their respective costs. To be conservative, we will assume a 2000 hour lifetime for the incandescent bulb Energyoptions 47