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Published online 20 May 2009 | Nature 459, 312-314 (2009) | doi:10.1038/459312a
News Feature
Lighting technology: Time to change the bulb
The incandescent light bulb is being phased out, but what will replace it? Stefano Tonzani investigates the technologies that are vying for our sockets.
The Centennial Light, which hangs in a fire station in Livermore, California, is the oldest working light bulb on Earth. The four-watt night-light was switched on in 1901 and has been shining almost non-stop ever since, consuming roughly 3,500 kilowatt-hours of energy in total.
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The only missing part is the evolution of the incandescent lamps, in the same leaping pace of the technologies refered in the article.I personally think that incandescent will still keep some room aside other technologies,and shall not be replaced but complemented in the necessary proportion.
There is certainly some evolution of incandescents, but by the very definition, the light is generated as a black body by heating the filament and will theoretically never reach the energy efficiency of LEDs, fluorescents, et al. That being said, governments and markets have very much lagged behind in considering only energy and visual appeal as the "figures of merit". The HEALTH quality of light is arguably more important in our modern world where we are vitamin D deficient (UVB), seasonally depressed (aided by sky blue, or cooler light) and have trouble sleeping (too much light at night) that could be causing a public health crisis. If you can't get daylight, use bright cool whites during the day and use a "bug light" bulb at night 2 hours before sleep time. It has a yellow coating and will not suppress your melatonin as much. Furthermore, I have not heard a good answer about the environmental cost incurred in making either an LED or others from "mine to house" (from X to china to US, for example). Due to their expense, I expect that the energy burned and waste created in producing one is high. Products should be stamped with a mark "we used X Joules of energy and produced Y grams of waste to make this and get it here". If the price is high, that indicates either less of an economy of scale, or, that someone burned a lot of resources to make it. We simply do not know.
Thank you for a somewhat less biased than usual article on the subject of replacing the incandescent lamp. The arguments against the ballast integrated compact fluorescent lamp are very considerable and are documented elsewhere, including at www.savethebulb.org. I would disagree that the incandescent lamp has seen little development over its considerable life. Currently Tungsten Halogen "energy saver" incandescent lamps offer 18lm/W compared with the Edison type incandescent that produced 2lm/W. Hopefully current research will improve incandescent efficiency to something in the region of 40lm/W if legislation allows! Percentage efficiencies in light generation are not a reliable indicator of efficiency as the highest percentage efficiency achievable by any white light source with perfect distribution in the photopic response of the eye is only 40%! As you point out practical LED products are only showing efficiencies in the range of 10lm/W to 60lm/W a far cry from the much publicised values upward of 100lm/W provided by LED manufacturers working under optimised laboratory conditions! There is also an absolute efficiency limit for LEDs somewhere around 240lm/W and you can bet this will never be approachable by a practical lighting system. Returning to lower efficiency light sources, particularly incandescent lamps, it is conveniently forgotten that heat provided in a room that requires heating, a large proportion of the world during the winter, has to come from somewhere. If a "high efficiency" light source is used more energy will need to be input through the heating system to maintain the same room temperature. There is a study undertaken by the UK Market Transformation Program that shows the actual saving of energy by swapping a Compact fluorescent lamp for an incandescent is only 17% of the indicated saving! It is good to see rational argument replacing the bad science that pervades the discussion and legislation around lighting. Kevan Shaw Director of Sustainability for the Professional Lighting Designers' Association
@ Ziggy There are some figures that appear in the working papers used for the EU legislation at www.eup4light.net, carefully buried in the Excel spreadsheets! The Incandescent lamp uses 1 joule of energy to manufacture , distribute and dispose, the Compact Fluorescent Ballast integrated requires 12 joules. Looking at the waste it is more concerning. 5 grammes of non hazardous waste in making the Incandescent, 108 grammes of which 78 grammes are hazardous in manufacture of the Compact Fluorescent which typically weighs about 80 grammes! Even if you "recycle " the CFLi there is little re-useable material that is recovered as there is a large proportion of predominantly plastic mixed waste and the glass cannot be cleaned and separated well enough for re-use as glass! Kevan Shaw
Policy makers should not forget that the incandescent bulb is an electric heater, so those using electric heat have no need to turn the lights out. On a cold day, indoors, in a building heated by fossil fuel, in a place where electricity is produced largely without fossil fuels, the bulb might even reduce carbon dioxide emissions. But when summer sets in it is time for more austerity - especially for those who use air conditioning, who must pay again to remove the heat the bulb produces. The best policy is not to ban the incandescent outright, but to promote research and development and encourage scientific literacy.
Is there a remote possibility to use naturally abundant, unlimited and free source of light-sun light directly? We talk of using wind, wave, water, solar and lots of other natural energy sources but why not simultaneously work on developing a technology where sunlight can be trapped and sent to wherever light is needed through some sort of cheap fiber optic tubes or something similar without electricity and later fluoresce in the night also? Or use two sources of lighting for day and night separately which saves enormous costs and much less polluting? May be in countries where sunlight is not enough and available for a short time it may not possible but in tropical and subtropical countries it can be used. Just an idea.Leela
I find the eup4light.net figure of 1 Joule to manufacture, distribute and dispose of an incandescent light bulb difficult to fathom. 1 Joule (1 Newton * 1 meter) is a small amount of work, equivalent to taking a 102g incandescent light bulb, and lifting it 1m vertically under the influence of the Earth's gravity. I find it hard to believe a 102g incandescent light bulb has only been lifted 1m against the Earth's gravity in its life from manufacture to disposal. I don't dispute the relative values offered one way or the other, but I believe the figures are given on the wrong scale.
Let's us not forget that Nikola Tesla substituted the tungsten filament in today's models of an incandescent light bulb for the carbon filament.
@ Leela, check out the DOE's work on using mirror concentrators on the roof and light pipes to bring indoor light into rooms that don't have windows or skylights. Similar is mentioned here: http://www.roofingcontractor.com/CDA/Articles/Cool_Roof/BNP_GUID_9-5-2006_A_10000000000000299069