Electric Light Has Come a Long Way: Where Do We Go from Here?
Even though nobody wants to go back to candles, there has been a lot of criticism of the poor old incandescent bulb, which has served civilization faithfully for over 130 years. In 2007, President G.W. Bush signed into law a requirement that “screw in” light bulbs will have to be 60 or 70 percent more efficient than today’s incandescent bulbs. The trouble is that 90 percent of the energy that goes into an incandescent bulb is required to heat the metal filament in the bulb to 4,000 degrees F, in order to get the bulb to light. The US law does not ban incandescent bulbs but those conditions are impossible for incandescent bulbs to meet. Manufacturers have phased out old-style 100-watt bulbs [The Washington Post]. “Traditional” incandescent bulbs have been banned from being sold in some states, including California.
So What Do We Replace Them With?
There are two current options that will meet the efficiency requirement of President Bush’s bill.
The Compact Fluorescent bulb is one option. The bulbs are cleverly engineered versions of the long fluorescent tubes you see in the ceilings of some stores and offices. What the engineers did is take the tube (which has to have a certain length and size to generate sufficient light) and bend them either into a U-shape or into a shape like a spring. Sometimes, the bulbs will be mounted in a glass cover so they look like incandescent bulbs. In each case, the bulb itself is mounted on top of a heavier-than-incandescent base which serves as the ballast.
The principle behind the fluorescent bulb is a little more complex than other lighting systems.
- When you screw the bulb into your lamp socket and turn on the light, AC electric current passes through an adapter in the base of the bulb which changes the current into direct current (DC). The base of the bulb also contains a “starter” and a suppression capacitor. This small system is called the ballast. It builds the current up to the level needed to start the bulb working and serves to maintain a constant voltage because fluctuating voltage in these bulbs will cause flickering lighting.
- The current is drawn through the tube which is filled with mercury vapor (and other gases). When the electrons in the tube crash into mercury molecules in the tube, the gas glows with invisible ultraviolet light.
- The glass is coated with a phosphorescent material similar to the kind that makes things glow in “black light.” The ultraviolet light makes the phosphorescent powder in the tube glow in visible light which is the light generated by the lamp.
There are two disadvantages of the compact fluorescent system.
The major disadvantage is that they have to be filled with mercury vapor which is very dangerous for the environment. These compact fluorescent light bulbs cannot be disposed of in regular trash but need to be specially recycled.
The second (perhaps less important) disadvantage is that these bulbs require the ballast. The presence of the ballast makes the bulb fitting slightly different from the standard screw-in fitting so the bulbs don’t fit in every socket. The ballast also slows the start of the light. When you turn the light on, there is a slight delay before the light turns on.
Light-emitting Diodes (LED lights).
The light-emitting diode (LED) lamp is the second option. LEDs are the result of a long history of research into special crystals called semiconductors (similar to crystals used in computer chips). These crystals simply glow when you attach them to an electrical source. The circuitry in the LED lamp is very simple. You simply need a current to change AC to DC current (AC is alternative current–the kind of current that comes through your plug from the electric company to DC (direct current–the kind of current that comes from a battery). The current reduced to the correct voltage is connected to the crystal and it glows on its own. This is a property of the matter in the crystal. You often see lamps where there is no apparent bulb, just a small piece of crystal at the base of the lamp that is the source of all the light. LEDs do not generate high temperatures. They tend to last a lot longer than incandescent bulbs and even longer than compact fluorescent bulbs.
The research into the property of these crystals to create light directly from electrical energy is leading to the development of new forms of lamps. Whole wall panels that light up, tubes whose surface has light-emitting property, and even light-emitting paper and flexible plastics.
Relumination was founded with the idea that automated lighting control and new low energy lights can save energy which is less expensive than figuring out ways to produce more. Contact us to learn more.