Can incandescent bulbs be substituted by LEDs?
LEDs: quality and effects
"Light Emitting Diodes (LEDs) produce visible light using the electroluminescence of a compound semiconductor crystalline material. This process is potentially more energy efficient than either incandescence or fluorescence. When connected to a power source, the flow of current triggers a quantum mechanical process inside the diode, which produces light in specific colors (usually red, green or blue). White light is created by combining the light from these colored LEDs or by coating a blue LED with yellow phosphor (Department of Energy 2008).
Organic LEDs (OLEDs) produce visible light when an electrical charge is applied to extremely thin organic materials layered between two electrodes. The technology is still in the early stages of development, but has the potential to efficiently produce visually appealing white lighting in a thin, flexible form that could compete directly with fluorescent and conventional LED lighting." (U.S. Department of Energy, Critical Materials Strategy, December 2010, p. 21)
Do LEDs pose a photobiological hazard? Given the limited spectral distribution of LEDs, there are no concerns about UV and IR radiation. What remains is the potential of photochemical damage to the retina from blue light.
2. Health effects of lighting systems using LEDs
See Health effects
3. Reliability of LEDs
Manufacturers of LEDs announce lifetimes of white LEDs up to 50 000 hours measured under laboratory conditions (junction temperature maintained at 25° C and fixed current); but in a current lighting system, measurements show that, in extreme cases, they may lose more than 70% of their brightness after 1000 hours of operation. The lifetime of the LED depends on the temperature of the junction and the electric current intensity, without forgetting the quality of production and integration. At present, the definition of the lifetime of a LED and the measuring method are not standardized. (ANSES_Report 2010, p. 40)
The junction temperature
The heat is "enemy No. 1" of LEDs, more specifically of white LEDs. LED operation at too high a temperature (and therefore high junction temperature of the semiconductor) has a dramatic effect on efficiency but also on other characteristics and performance of LEDs such as the flux, the spectrum (and thus the color), the polarization voltage, and the life. To take advantage of the interesting properties of LED (flux, efficiency, durability, quality of light emitted), integrators must take into account the heat generated by the LED and qualities of this component to evacuate the heat. However, even with excellent thermal management of LEDs in the final application, the resulting temperature at the junction of the semiconductor is far from the 25° C, reference temperature of most manufacturers. (ANSES_Report 2010, p. 207)
LED lamp life expectancy depends on fixture type and usage scenario
4 September 2014 in LEDsMagazine: LED lamp life expectancy depends on fixture type and usage scenario. "Consider for a moment the ecological predecessor of the LED lamp — the CFL. Has it become common knowledge among consumers that CFLs will not perform as claimed in some fixture applications? (...) In fact, LED lamps can and do fail even sooner and of course at higher fiscal cost. (...) The general public needs a range of life expectancy as the lamp is used by the consumer. We have to move beyond the never and always paradigm, or we risk having LED technology disappoint the buying public more than CFLs have."
Conclusion: The quality of the current supply of LED lamps is unsatisfactory.
4. LEDs can damage the paintings of great masters!
The Dutch newspaper De Volkskrant, February 15, 2011: It was found that over a period of more than one hundred years many original yellow colors on Vincent van Gogh's paintings slowly became brown. An international team of scientists suspected that the discoloration could be caused by the chrome that the painter used in his paint. On January 4, 2013, De Volkskrant reported the reason of this discoloration, referring to the doctorate of Letizia Monico at the universities of Antwerp and Perugia. 'Our research shows that middle chrome yellow, which is a yellow hue with warm glow and is most often used, is chemically fairly stable.'
Van Gogh also uses the lighter lemon yellow and even pale primrose yellow. 'They react very intensely to light beams. After only a few days they colour during our tests to brown and olive green. These unstable forms of chrome yellow paint we found among others in some very famous paintings, such as the Portrait of Gauguin and Vase with sunflowers.'
Also other painters used both the stable and unstable forms of chrome yellow paint such as Paul Cézanne and according to the Belgian newspaper De Standaard of 4 January 2013, also Rik Wouters.
Because the lemon and primrose yellow extra sensitive to blue and green, it is risky to illuminate those artworks with LEDs because they emit a high proportion of blue light. LEDs can damage the paintings of great masters!
5. LEDs use less REEs than CFLs but REEs remain crucial
General lighting service (GLS) sources are defined as white-light sources used to illuminate spaces. (Leslie Lyons, Part 1)
White light LED devices are generally based on one of three approaches for producing a distribution of
visible wavelengths that are perceived as "white light". These are:
The majority of white light LEDs in production today are phosphor converting LEDs based on galliumnitride, emitting blue light between 450-470 nm (DOE, 2011). This blue light excites a yellow phosphor, usually made of Ce3+:YAG crystals that have been converted into a powder. As the LED chip emits blue light, some is emitted directly through the phosphor and some is converted by the phosphor to a broad spectrum centered around 580 nm (yellow) by the Ce3+:YAG. This yellow light stimulates the red and green receptors in the human eye, resulting in a mix that gives the appearance of white light. (Same source, p. 19)
Summary of LED Colors and Common Chemistries (Same source, p. 17)
Toxicity of used materials: Particularly those workers involved in the manufacturing process and destruction of LEDs could be exposed.
Phosphors accounted for 7% of all REE usage by volume and 32% of the total value in 2008 (Kingsnorth 2010). The exact composition of phosphors, including REE variety and weight percentages, differs by manufacturer and is considered proprietary information. Emerging lighting technologies have dramatically lower REE content than fluorescent lamps. (DOE_2010, p. 21-22)
In the short and medium terms, the demand for LFL and CFL fluorescent lamps using REEs in their phosphor formulations is expected to increase. (...) In the long term, LED and OLED technologies will likely capture a significant share of the lighting market as their cost and performance make them increasingly competitive with fluorescent technologies. This change could mitigate the demand increase for REE phosphors.(p. 22-23) Light emitting diodes (LED) use little or no REEs and could replace fluorescent light bulbs. LEDs for room lighting are not expected to be cost competitive until the medium term. (DOE_2010, p. 120)
Because of the new quotas introduced by China, the availability of rare-earth elements causes some concern. (ledsmagazine.com)
Gallium demand is growing in several applications including light-emitting diodes (LEDs) used for liquid crystal displays in televisions and notebook computers and solar cells. In addition, its material intensity in solar cells has been declining thanks to efficiency improvements. Electronic components have represented about 98% of U.S. gallium consumption since 2003. In 2009, about 67% of the gallium consumed was used in integrated circuits (ICs). Optoelectronic devices, which include laser diodes, LEDs, photodetectors, and solar cells, represented 31% of gallium demand. The remaining 2% was used in research and development, specialty alloys, and other applications. The global economic downturn hurt LED markets, although emerging LED market segments, such as for LCDs in televisions and notebook computers, still showed growth. At the same time, record-making solar cell efficiencies are reducing the need for gallium, among other materials, in making thin film solar cells (USGS 2010c).
The United States represents about 25% of the global annual consumption of gallium. Since 1982, the United States has been dependent chiefly on imports for meeting its annual gallium demand. (p. 40)
Indium base material for the majority of current LEDs is a rare element: 61st in abundance on the Earth's crust (0.24 ppm (parties par million) by weight). Indium is not exploited as the main product (there are no mines indium). Indium is a subordinate product of zinc, but also of tin. Indeed, it is ranked second on the list of the rarest strategic materials. Although a LED junction uses a tiny amount of this element, it is impossible to recycle it after use. Today the world's reserves amounted to 5600 tons and are therefore sufficient for the years to come, but they are not inexhaustible. Today, more than 75% of indium is used by the flat screen industry for the manufacture of transparent electrodes in ITO (Indium Tin Oxide). According to analysts, the most likely scenario is that the industry will face a situation of periodic short-term "crisis" (2-3 years). (ANSES_Report 2010, p. 215)
LEDs: Higher toxicity and resource depletion
The new LED light
For the future a new form of LED light is introduced. The ideal is a tunable white light produced by a combination of red, green and blue LEDs. During the day, different hues can be amplified or suppressed so that the natural light of the sun is mimiced. (Jeff Hecht, Better than sunshine: See life in an improved light, New Scientist, 6 July 2012.) Article
After having accomplished the ban on incandescent bulbs, and leaving the CFL technology unsatisfactory for the consumers, the lamp manufacturers are now focussing strongly on the lucrative LED technology. The consumers have to pay a huge price for a dangerous and disagreeable product. The rights of the consumer are denied. They don't understand why the EU supports this course of events. Even managers are not happy with each decision: Products shall not be banned if no suitable and affordable good quality replacement products are available. (Lars Stühlen, ELC)
It is very important to stress that LEDs produce a different type of light in comparison with incandescent light. So, they cannot be a substitute product! A ban of incandescent light bulbs has led to a very reduced choice of light products. This is the more incomprehensible because the light belongs to the necessary elements influencing our mental and physical health (together with food, water and air). Our sight is more valuable than a possible saving of electricity consumption. And our environment has much less to endure from incandescent light bulbs than from CFLs or LEDs. This is proven by Greenpeace in Berlin in 2007. By destroying 10,000 incandescent light bulbs, they showed that the clearout of the broken lamps was no problem at all! Imagine what would happen when 10,000 CFLs or LEDs were destroyed! A whole quarter should be evacuated! Let us eliminate the burden of toxicity and resource depletion potentials needed to produce the 'energy saving' light bulbs.
Last updated on 15 August 2017