A light-emitting diode (LED) is a semiconductor that emits light when the electric current passes through it. The original LEDs from the early 1960s only emitted a very low intensity red glow light. Early LEDs have commonly been used as airplane and automobile indicator lights, in TV remote control units, and as calculator read outs.
LED lighting technology has advanced in recent years to include wavelengths that are not only visible, but also very bright/having a lot of luminescence. Modern LEDs capable of producing bright white light are now being used more frequently as energy efficient replacement light bulbs alternative to CFLs and incandescent light bulbs.
How do LEDs work?
LED lights glow when an electric current passes through the device causing electrons to take up empty electron holes inside the device at a lower energy level than that of free moving electrons. Once an electron takes up an empty hole at a lower energy level, the excess energy gets released as photon that we see as light, an effect called electroluminescence. The color of the light is established by the resulting energy gap in the semiconductor. LED lights are designed to use electrical power of between 30 and 60 mW. Continuous use LED lights use a larger semiconductor in order to handle bigger outputs of power, and have a heat sink mounted on in order to keep the device from overheating.
Pros and Cons
LED lights have a number of advantages over CFLs and incandescent light bulbs. Latest bright LEDs use far less energy, and last far longer than CFLs or incandescent lights. Unlike CFLs that need some time to warm up, LEDs can be turned on instantaneously, providing a reliable and durable source of light that is up to four times more energy efficient than CFLs, and up to 12 times more energy efficient than incandescent light bulbs.
LEDs' Prohibitive costs to most homeowners
Currently LEDs costing between $40 to $100 per LED light bulb are not very affordable for your average consumer, but that situation is expected to change as LEDs prices are expected to decrease by some 15-20% per year. Not only that as LED's prices decrease their performance is expected to increase. Who knows, maybe in a few years LEDs will have rendered CFLs and incandescent obsolete?
Reliability and Durability
Most LEDs that were created in the 1970s and 80s are still functional today. Modern bright LED lights have a life expectancy of 25,000 and 100,000 hours, provided they are used under optimal conditions being lit up for 8 hours per day. LEDs perform best under normal conditions. If you were to use LEDs in extreme heat such that LED light bulbs would overheat, then higher temperatures could actually lower the life expectancy of your LED light bulbs. Typically, LED lights will gradually fade over time rather than burn out immediately.
Potential Hazards
Some very bright LED lights could potentially cause eye damage and are classified as Class 2 LEDs. LEDs are considered safe when used under normal conditions, and very few LEDs pose any risk of temporary blindness. According to the state of California, all LED lights with the exception of low-intensity yellow can be hazardous due to levels of copper, Pb, nickel, or silver. Unlike compact fluorescent light, LEDs do not contain mercury found in CFLs, which could also contain arsenic and lead (poisonous/hazardous materials).
LEDs Vs. CFLs
Compact fluorescent lights (CFLs) are also known as energy saving lights, and were designed to replace many existing incandescent light bulbs. As such, most CFLs can fit into incandescent light fixtures. CFL bulbs are comparable to incandescent, and generally provide the same amount of light. An advantage to CFLs is that they use less power, and can last up to eight times longer than incandescent.
Current biggest advantage of CFLs vs. LEDs is a substantially lower cost of CFLs vs LEDs.
Evolution of Florescent Lights
An important development in fluorescent bulbs came with the replacement of the electromagnetic ballasts with ballasts that are electronic. CFLs do not experience flickering or slow starts that traditional fluorescents were known for. Integrated lamps in CFLs allow for a simple replacement of incandescent bulbs with the CFLs. Non-integrated CFLs are typically more expensive.
CFLs Vs. Incandescent Lights
The average lifespan of CFL bulbs is at least 8 times, and sometimes as much as 15 times longer than incandescent bulbs. The rated lifespan of a CFL light ranges from 6,000 to 15,000 hours compared to the 750 to 1,000 hours of an incandescent light bulb. If a CFL light is turned off and on habitually, their lifespan can be reduced to nearly that of an incandescent light bulb, though.
CFLs Do a lot of good in Third World Countries
CFLs do have a few disadvantageous when compared to incandescent bulbs. A CFL bulb warms up to complete brightness only after a few minutes, while incandescent only needs a fraction of a second to reach full brightness. In cold temperatures, CFLs can take even longer to reach full brightness. Modern CFL bulbs are very cost effective and are leading the way for relief agencies to replace kerosene lamps in third world countries.
Recycling of CFLs
Environmental concerns are also at the forefront of many recycling company policies as leaking mercury can cause problems if released improperly. Many states in America and countries within the European Union regulate fluorescent bulb disposal and recycling. If you want to recycle your old CFLs properly, then simply bring them back to the store where you bought them, and they will recycle them for you.
How do Incandescent Lights Work?
Incandescent bulbs have been the standard lighting choice for since Thomas Alva Edison invented them. Incandescent bulbs work by heating a metal wire inside the glass bulb until it gets hot and starts to glow. The glass bulb is filled with an inert gas to prevent air from reaching the filament.
Good ol' Incandescent Lights are fading away...
Modern CFLs and LEDs are more environmentally friendly and longer lasting, are thus justly replacing incandescent bulbs. Many countries are in the process of phasing out incandescent bulbs completely, and some have already done so.
Why Incandescent Bulbs are Obsolete?
Almost all of the energy that is emitted by an incandescent bulb is heat rather than light, meaning that incandescent lighting is not very energy efficient. Incandescent lighting emits much more heat than compact fluorescent lights or LEDs, and therefore makes air conditioning costs rise in the summer.
Hybrid Incandescent Bulbs
While the initial cost of an incandescent bulb is less than that of a CFL, the wasted energy costs are much greater, and replacement intervals are too short compared to CFLs. Some incandescent light bulb manufacturers had been working to raise the efficiency levels of the bulbs, but have been unable to reach their initial goals. Hybrid bulbs have shown to be as much as 30% more efficient than original incandescent bulbs, working to redirect and recycle the excess heat back to the lighting filament.
State of The Lighting Industry
While manufacturers of incandescent light bulbs are trying to hold on, modern consumers tend to opt for CFLs, as incandescent light bulbs are too old, and LEDs are still too expensive. In the mean time, LED lighting manufacturers are continuously working on improving the performance of their products and are gradually decreasing their costs in order to edge out their competition. Early adopters, and green building conscious businesses are not scared off by a higher price tag of LEDs and take advantage of all that modern LED lighting technology has to offer. They are the primary beneficiaries of the state-of-the-art lighting products such as dimmable LED lights designed to work with standard dimmers. As for the rest of us, we are holding on till the prices drop even further. Perhaps in a few years consumers will be more open minded and ready to pay a higher price for LEDs.