Flipping the On-Switch to Energy Efficient Lighting. By Patrick J. Ritsko

Transcription

1 Flipping the On-Switch to Energy Efficient Lighting By Patrick J. Ritsko It always happens when you least expect it. You step foot into a dark room and lift your hand to feel the familiar wall around you for the light switch. As you would expect, the light flashes on but only for a brief second. Just then, you hear the faint sound of a burnt filament whip the inside of a glass bulb. You find yourself reaching into the pantry for a new incandescent and into the closet for the step ladder. This ritual is practiced several times a year in every household and chances are you have been doing it all your life. But what if we could give our wallets and the environment a relief from the expenses of changing an incandescent bulb? Is innovation to interior lighting burning out the well-known bulb? Are the light bulb jokes becoming a theme of the past? The future is shedding light on a definite yes, and it is no joke. For twenty-five cents, a 60-watt incandescent served as a simple lighting device that usually ran a lifespan of a year before it needed replacing. It is a lighting device that did not see any major renovations since the 1920 s. Despite the incandescent bulb s inexpensive and simple characteristics, the average of 40 operational incandescent bulbs per American household turned out to be a quiet army of heated filaments contributing to the daily expenses Americans face every day. According to Gregg Seaman of the family business Earth Easy, home lighting by these heated filaments amount to twenty-five percent of the American household energy budget. With our increasing energy demand, it appears the future of the incandescent bulb is dimming, while the futures of the compact fluorescent light (CFL) and the light-emitting diodes (LEDs) appear ever-so bright.

2 According to the United States Department of Energy, America s electricity demand will increase at a rate of 1.1 percent each year over the course of the next few decades. This rise in demand will proportionally increase the workload of coal-fired utilities, which continue to act as both the leading source of power for America as well as a major pollutant of greenhouse gases including carbon dioxide (CO 2 ). With environment consciousness on the agendas of politicians and everyday citizens alike, Americans are now striving to live greener lifestyles by fronting the initial cost of energy efficient products and cashing in on the long-term benefits. Americans understand that the investment of energy efficient products will reduce the negative externalities on the environment and will eventually pay back the consumer in energy savings over time. But how does the energy efficient CFL or the LEDs fit the realm of a green-planet utopia? It is likely that the environmentally friendly characteristics of CFLs are reducing energy costs for consumers which are stimulating the escalation in sales. General Electric, a leading manufacturer of CFLs, states that a CFL bulb uses 75 percent less energy and generates 70 percent less heat than an incandescent light bulb. Energy Star, an energy program established by the U.S. Department of Energy, supports CFLs due to their effectiveness in reducing greenhouse emissions from power utilities. To support their statement, Energy Star has compiled several convincing statistics. One statistic claims that if every household uses just one CFL bulb, greenhouse gases emitted by power utilities will be reduced at an equivalent level of eliminating 800,000 cars off the roads. Another statistic states that Americans could save $600 million annually in energy costs if every household used only one CFL. Both General Electric and Energy Star agree that the use of CFLs can save the consumer up to $30 in energy costs over the life course of just one bulb!

3 Unlike the traditional incandescent light bulb, the CFL contains no inner filament to produce light so it generates less heat (i.e. less wasted energy). Instead, it uses a combination of incandescence (producing light through radiating atoms) and luminescence (atoms emitting light energy at low temperatures) processes to produce visible light. Inside the corkscrew-shaped glass of a CFL are argon and mercury gases. Once these two gases come in contact with an outside electric current, high frequency light on the ultraviolet (UV) spectrum is produced from the incandescence of the inner gas molecules. Initially, the wavelengths produced are invisible to the human eye because they fall within the wavelength magnitude of the UV spectrum. Depending on the magnitude of the source electric current, the distributed UV light has wavelengths between 10-7 m and 10-8 m. After these UV rays are scattered within the bulb, the wavelengths come in contact with the inside phosphor coating the glass. The phosphor produces light by luminescence, which is very similar to how glow-in-the-dark material absorbs outside wavelength energy to produce light without generating heat. Once the high energy UV light from the gases is absorbed by the phosphor atoms, the atoms emit energy waves on a magnitude that is exponentially smaller than UV light. The final product is visible light. As a consumer, you should be aware that CFL bulbs have several shortcomings and limitations. CFLs are non-dimmable, unless otherwise noted on the package. Also, CFLs initially require more electric energy when first turned on in comparison to a regular incandescent bulb. Thus, it is recommended not to install a CFL in an environment where light is needed for only a brief period of time. For example, using an incandescent bulb for a minute or so as your source of closet light to pick out your attire for the day would actually be more energy efficient than using a CFL. Conversely, using a CFL on your desk lamp to do work all night will pay off over any other light source. In addition, the 5 mg of mercury within the CFL

4 could potentially be harmful upon breakage of the glass or disposal of the bulb. Manufacturers are addressing this issue by offering instructions to properly recycle CFLs. Want a brighter, innovative solution? Although not commonly installed for interior lighting just yet, the alternative to CFLs in the energy efficient lighting category are LEDs. LEDs are traditionally used to illuminate the everyday items we use and see every day including watches, televisions, small flashlights, Christmas lights, and even traffic lights. A single LED at work is usually not enough to satisfy lighting needs; so, diodes are commonly grouped together in lighting products to collectively provide bright, white light. The phenomenal LEDs have a lifespan of approximately 15 years if used daily, which is 15 times longer than the lifespan of an incandescent and nearly twice as long as a CFL. LEDs are more efficient than CFLs in the sense that the diodes generate very little heat and use only 2-10 watts of electricity. As you might have guessed, the diodes are the necessary ingredient to produce light efficiently in this unique form of illumination. The diodes in LEDs are semiconductors and therefore, are poor conductors of electricity. However, depending on the impurity of a given semiconductor, it can have an excess number of electrons when an electric current flows through it. Semiconductors with excess electrons are either an N-type or a P-type of material. An N-type of semiconductor provides extra negative conducting electrons, while a P-type adds extra atoms of the semiconducting material to increase the free charge carriers. The diodes are conveniently aligned so the electric current flows from the N-type to the P-type. When electrons flow in a current from the N-type material to the P-type, they come across unbalanced atoms (i.e. atoms that are lacking the desired number of electrons in their orbitals). Typically, the free electrons would join these orbitals, but they are in such a high

5 energy state that the atom needs to downgrade to a more stable energy level. This downgrade forces a change in electron configuration which emits energy photons. As a result, light is created in the visible or infrared ranges on the electromagnetic spectrum. Depending upon the semiconductors elemental and chemical composition, the color of light produced will vary. In the past decade, LEDs have struggled to be in widespread use due to their expensive production costs. However, breakthrough research at Purdue University in 2009 successfully introduced the use of metal-coated silicon as a semiconductor instead of bits of sapphire that were previously used. Thanks to this innovation, LEDs are becoming more marketable and are now competing alongside CFLs on the lighting market. The methods we use to illuminate our lives are rapidly changing. CFLs and now LEDs are becoming commonplace in restaurants, schools, business buildings, and homes alike. The next time you see the light flicker and hear the filament snap, consider your alternatives before reaching for another incandescent. The science behind CFLs and LEDs is shedding light on a brighter future for the environment and for our energy budgets. Taking the necessary steps to fade out the incandescent bulb is one way consumers can reduce energy consumption and the allimportant carbon footprint we leave on our environment.

6 References Compact Fluorescent Light Bulb. (2011). General Electric. Retrieved December 20, 2010 from, Compact Fluorescent Lights. (2010). Energy Star. Retrieved December 17, 2010 from, / Energy-Efficient Lighting. (2010). Eartheasy.com. Retrieved January 16, 2011 from, /eartheasy.com/live_energyeff_lighting.htm Gache, G. (2008, April 9). How LEDs work. Softpedia. Retrieved January 17, 2011 from, /news.softpedia.com/news/how-leds-work shtml Harris, T. (2011). How can a diode produce light? HowStuffWorks, Inc. Retrieved January 16, 2011 from, Information on compact fluorescent light bulbs (CFLs) and mercury. (November 2010). Energy Star. Retrieved January 5, 2011 from, /change_light/downloads/fact_sheet_mercury.pdf LED breakthrough may revolutionize lighting. (January 2009). Science Daily. Retrieved January 17, 2011 from, /led-breakthrough-may-revolutionize-lighting/