Sunday, January 23, 2011

Light Bulbs

(Please read this article from Scientific American (Jan 15, 2010) and leave your thoughts as a comment, a couple of sentences)

Building a Better Light Bulb

The race is on to develop the modern light bulb, but it may be that the modern light bulb won't be a bulb.

Incandescents -- The Old Standard Bearer

Since the days of Thomas Edison, the incandescent light bulb has been the king of illumination. It works on a basic principle of physics: the hotter a body is, the more light it radiates.
In an incandescent light bulb electrons are forced through a filament to make it so hot that it glows. Because so much of the electrical current's energy goes into heating the filament, incandescent bulbs tend to be very inefficient. And so, acting on today's low-carbon imperative, many people are looking to replace the incandescent with something more efficient.
Others have not yet given up on the incandescent and are working to make that 19th century lighting technology as efficient as its rivals -- the compact fluorescent light (CFL) and light-emitting diode (LED) (both described here).

CFLs -- The (Relatively) New Kid on the Block

Seemingly poised to replace the incandescent, CFLs work on the basis of fluorescence instead of incandescence.
A beam of electrons is sent through a gas causing the electrons in that gas to be excited from their ground, low-energy state to a higher energy state. When the electrons relax back to their ground state, the extra energy is released as light via a photochemical reaction.
Because fluorescence does not depend on heating the gas, CFLs are more efficient than incandescents; typically CFLs use about 75 percent less energy to produce the same amount of light as an incandescent.

LEDs -- Closing Fast

But there are people out there who don't like CFLs -- they don't care for the light quality, the flicker, and the fact that they usemercury. Not to worry; there's an up-and-coming alternative -- commonly referred to by its three-letter moniker LED.
LEDs work on the same fluorescence principle as CFLs but with a twist. Instead of sending a current through a gas, LEDs make use of a crystal semiconductor with varying properties from one end to the other (hence the term diode). Electrons on one end of the diode tend to be in a high-energy state and at the other a low-energy state. When exposed to a current, electrons flow from the semiconductor's high-energy end to its low-energy end, and the energy change shows up as light.
typical LED is slightly more efficient than a CFL, and has the added advantages of a much longer life expectancy and no mercury. That's why many experts believe that while CFLs may be a temporary replacement for the incandescent, the future of illumination will more likely belong to LEDs.

Not So Fast, Mr. LED

While LEDs may eventually win the illumination race, they are nowhere close to the finish line. They're expensive, and the light they give off can be harsh (although advances may have already made some complaints in this area a thing of the past). But still, in terms of giving either incandescents or CFLs a run for the money, LEDs seem relegated so far to primarily flashlights, where long life and low power requirements are at a premium, and outdoor applications, where the harshness of the light is not an issue.

Snow Blind

While we're on the subject of LEDs, here's something folks had not anticipated: LEDs don't work in the snow.
Because incandescents generate heat, they can melt away any snow or ice that might land on them. But the small amount of heat from LEDs means that when they are outside in snowy conditions, they might well get buried. Is this a problem? Potentially yes, since LEDs are being deployed in traffic signals in no small number across the country.
Earlier this month, Joanna Bush of the Department of Transportation in Wisconsin, which has transitioned 90 percent of its state-owned signal lights to LEDs, admitted that "we certainly do see crashes and accidents [during snow storms] attributed to the fact that people can't see the heads," referring to the blocked colored lenses of a traffic signal.
In her view, though, the problem of snow accumulation on the traffic signals "isn't enough to convince us to move over from LEDs."
So while the world awaits a high-tech solution to the problem of snow-obscured LED traffic lights, Wisconsin's DOT, not wanting to sweep the potentially serious problem under the rug, has its own quick fix: "dispatch workers with brooms to clear the lenses." The 21st century meets Disney's The Sorcerer's Apprentice?

Feel the Glow

It could turn out that the next illumination king could be none of these three.
A Welsh company called Lomox is working on a technology based on organic LEDs that would cause walls that are coated with the product and charged with a low-voltage current to glow.
The company claims that its technology will be two and a half times more efficient than the best bulbs available today and will illuminate a dimmer-equipped room in much the way sunlight brightens a room.
Cool. Can't you just see it: Ten years from now, you sit down with your e-reader in your dark room on a snowy winter night and command a robotic broom first to switch on the wall and then to go outside and sweep off the yard lights.

(I found the article by going to the Scientific American website and searching "light bulb")


Anonymous said...

This actually sounds really cool. I know in my house we have some LED lights and they do cut down on energy, yes they cost more but in the end you are producing less energy. I think using LEDs in traffic would be cool.

Anonymous said...

This is interesting as it poses the wuestion is it better to save in the long run or short run? We have all three in our house, and the LEDs and CFLs are certainly better than the incandescents. It's almost like Blu-Ray vs HD DVD. We won't know who will win until after the fact.

Anonymous said...

I personally like LED lights. They're brighter and they look better than regular lights. The only downside is when cars have them and you're driving at night and BAM! They're eye level to you. It looks like they have their highbeams on, but in reality, they're just LED lights. But they are more efficient compaired to incandescent bulbs. But if people want to use an incandescent over an LED, let them. Just because something is "good for the enviroment" or "efficient" doesn't mean you HAVE to use it.

Anonymous said...

This is an interesting article. The fact that LEDs don't generate heat and Incandescents do. Also, Joanna Bush of the Department of Transportation is avoiding a soon to be harmful situation. The light bulbs in the traffic lights now generate heat to melt the snow away, with the LEDs they won't be able to do that.

Anonymous said...

I think it would be easy to figure out a way to keep the snow off the LED lights. Some cars already are equipped with little wipers on their head lights and some cars have heated mirrors. so i do not see why they cant figure out a way to keep the lenses of LED lights to stay warm or clean.

Anonymous said...

I think it is fantastic that companies are trying to create a different type of light bulb, because the origianl incadescent light bulb does use too much energy. In an environmentally friendly a new type of light bulb is just what we need. The CFL light bulbs do seem to be a little dangerous because of the mercury that is inside of them. Light bulbs are easy to break, and I could just see myself dropping one and then becoming really sick. I do like the LED lights better, but they are really bright and give me a headache so I do not think that they will be the next popular light bulb, but the companies are getting closer. I think that it is funny that there have been accidents due to the snow build up around the lights, but it won't persuade the city to change the kind of light that they use. The lights are there to help prevent accidents not cause them. The organic LED that the Lomox company is creating sounds complicated but very interesting.

Anonymous said...

I am a fan of the LED lights. They are so much brighter and more efficient than the incandescent light bulb. i dont think that LED lights should be used in cars because it seriously blinds you when cars with them down the road. it would be nice though because cars with them can illuminate their surroundings better. but nonetheless they have their perks and downfalls. *