The Rise of LED Lighting: 50 Years of Development|
Article- October 2012 By Larson Electronics.com
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At their current rate of development and advancement, LEDs are projected to represent half of all light fixtures sold in the United States by the year 2015. Already, consumers who switched from the almost obsolete incandescent bulb to compact fluorescents because of their higher efficiency are beginning to again upgrade to the higher value LED. By 2030, LEDs are expected to dominate the lighting industry in much the same way that the incandescent bulb has for the last 130 years. As the costs for energy increase, global climate concerns continue to grow, and efficiency standards around the world move ever higher, experts predict a heavy reliance on extremely efficient light sources to manifest itself fully. With LEDs now rivaling or surpassing all other forms of lighting in efficiency and output, and being more easily applied to a wider variety of applications, they have become a natural next step in the evolution of how we produce light.
At the recent Holonyak symposium entitled "LED: 50 Years," scientists and experts from around the world gathered to recognize the contribution to lighting technology made by Nick Holonyak Jr. when he developed the first viable LEDs in 1962. Holonyak was perhaps one of the most visionary electrical engineering scientists of his time, proclaiming in 1963 shortly after he developed the first practical visible light LEDS that LED lighting would eventually replace the incandescent bulb. Not everyone shared his enthusiasm, and the slow advancements in LED technology that resulted from then plentiful and cheap electricity and cheap light bulbs served to help relegate LEDs to minimal use in low powered applications like indicator lighting on appliances and calculators. By 1989 however, Holonyaks continued success in semi-conducting and laser technology development helped keep LEDs just on the edge of mainstream use, and Holyonyak began serious recognition as a major driving force in the field of electrical engineering.
Now in 2012, it appears Holonyaks’ prediction was indeed almost prophetic and his reputation as a visionary in electrical engineering solidly cemented. LED technology has seen explosive growth over the last decade, and LEDs have now become a multi-billion dollar industry. Much of this growth is attributable to the increasing global concerns with energy efficiency and climate change we noted earlier. Additionally, across the globe nations have begun enacting tough new energy standards that all but guarantee to cast the incandescent bulb into obsolescence. Clearly a more effective and efficient form of lighting is now needed, but there were other possibilities besides LEDs which also showed promise such as the compact fluorescent lamp. So why have LEDs moved definitively to the forefront of lighting development? The answer lies not only in their efficiency, but in the nature of their construction as well.
While LEDs are indeed extremely efficient, this is not their only strength or advantage over other forms of lighting. In keeping with their ability to reduce costs through lower energy use, LEDs also offer savings in the form of improved longevity as well. A typical incandescent bulb normally has a lifespan of approximately 1500 hours. The main benefit here was that despite their relatively short lifespan, incandescent bulbs were cheap and easy to replace. However, particularly in commercial or industrial lighting applications, frequently replacing bulbs can become quite costly indeed as it is necessary to not only include the cost of replacement bulbs, but the maintenance costs from man hours spent performing replacements as well. Now that LEDs are beginning to decline in price, they are beginning to show a positive net savings in maintenance costs due to their longevity. A typical LED fixture used in a commercial warehouse for instance is expected to provide 50,000 to 70,000 hours of operation before requiring replacement. The cost of replacing incandescent bulbs to match this lifespan alone would put the cost of the incandescent at or above that of the LED fixture. When we also figure in the money save from greatly reduced maintenance intervals, this savings becomes even greater. Combined with the much higher efficiency of the LED, this results in an even greater savings.
Another characteristic of LEDs which has served to boost them past other forms of energy efficient lighting is there extreme versatility and durability. As we mentioned earlier, compact fluorescent bulbs were considered a possible replacement for the incandescent bulb. However, the CFL has many shortcomings which limit its practicality and versatility. The CFL does not lend itself well to applications requiring tightly focused light output such as spotlighting. They cannot produce the output needed to serve in highbay applications with any effectiveness either. They are prone to severely degraded performance and lowered lamp life from frequent on and off cycles, and extremes of cold or heat can cause premature failure of the CFL as well.
LEDs on the other hand suffer from none of these failings. They adapt quite well to floodlight or spotlight applications, can be used under a wide range of environmental temperatures, and are not sensitive to frequent on and off cycling. Additionally, the small size and rugged solid state design of the LED provides even greater benefit for those in the industrial and commercial sectors as not only can LED fixtures withstand wide temperature extremes and frequent on/off cycling, but physical abuse in the form of impacts and vibrations as well that would outright destroy an incandescent or CFL.
Of course, no mention of LEDs would be complete without a nod towards their primary attractive feature, efficiency. As many experts have already noted, the incandescent bulb makes a better heater than it does light source. As much as 90% of the electrical power fed into an incandescent light bulb is wasted as radiated heat, resulting a very poor 15 lumen per watt light production ratio. LEDs on the other hand have a lumen per watt ratio of 60 to 100 lumens per watt depending upon the particular LED design in question. This gives the LED an up to 80% better efficiency than the incandescent, and is better even than most CFL’s.
As can be seen, the reasons for the explosive growth of LEDs are many and varied. Professor Holonyak was indeed a true technological visionary considering that not only did he predict the eventual dominance of the LED, but he did so at a time when most of the reasons for this rise to dominance had yet to become apparent.