Lighting accounts for 20 percent of all electricity use in the US, but a great deal of the energy used to produce that light is wasted as heat. Living on Earth’s Cynthia Graber reports on light-emitting diodes, a new energy-efficient technology that experts predict may take over the lighting industry.
CURWOOD: Those of us who live in the industrialized world take lighting for granted. Reading lights, streetlights and headlights, even that little light in your refrigerator.
About 20 percent of all energy used in the United States goes to power lights, and almost all of it is wasted. But now come the new light emitting diodes, or LEDs. These are far more efficient at using electricity for illumination. As Living on Earth’s Cynthia Graber reports, many people are calling LEDs the future of light.
MUSIC: “Listen dear, I’m afraid to go home in the dark…” (fade under)
GRABER: At the end of the 1800’s Thomas Edison invented the light bulb and transformed the world. A New York Herald reporter described this scene in downtown New York in 1882.
MALE: In stores and business places throughout the lower quarter of the city, there was a strange glow last night. The dim flicker of gas, often subdued and debilitated by grim and uncleanly globes, was supplanted by a steady glare, bright and mellow, which illuminated interiors, and shown through windows fixed on wavering. It was the glowing incandescent lamps of Edison used last evening for the first time.
GRABER: The incandescent bulb we use today hasn’t changed much from Edison’s days. An electric current goes through a filament. The filament becomes so hot it glows, producing light. But 95 percent of the electricity used to light up that incandescent light bulb gets wasted as heat. So scientists introduced a more efficient fluorescent bulb in the 1940s.
Fluorescents work by passing electricity through gas in a tube, which creates light. But the fluorescent bulbs never took over the residential market, because the harsh color isn’t as pleasing as the warmer glow of incandescence. Now, scientists are developing something new that they hope will be both easy on the eye, and energy efficient. Secretary of Energy Spencer Abraham spoke about the promise of light emitting diodes, or LEDs, at the Energy Efficiency Forum in Washington, DC this summer.
ABRAHAM: And it is to fluorescent lamps what the automobile was to the horse and buggy. It’s a revolutionary technological innovation that promises to really change the way we light our homes and our businesses.
GRABER: An LED is made up of layers of electron-charged substances. When an electric current passes through the layers, electrons jump from one to the other and give off energy. The amount of energy the electron gives off depends on the type of material used for the layers. And it’s this energy that determines the color of the light. LEDs can be made in almost any color of the rainbow, and scientists say they will be significantly more energy efficient than either incandenscents or fluorescents.
Jerry Simmons is the head of the LED research team at Sandia National Lab in New Mexico. He says if the new technology penetrates half the entire lighting market within the next 15 years, it could greatly reduce total energy consumption.
SIMMONS: It’s equivalent to about 20 billion dollars a year in electrical rate charges. It’s the same amount of energy that’s used by all the homes in the states of California, Oregon and Washington.
GRABER: Color Kinetics is a Boston-based company designing creative uses for LEDs. An engineer types a few clicks at a keyboard and lights up pinpoints of red, green, and blue LEDs contained in a dozen four-foot-long plastic tubes. The color of light in the tube depends on how many LEDs are lit and in what combination. Kevin Dowling is Vice President of Strategy and Technology.
DOWLING: Our lights can produce 16.7 million colors. Although it sounds like a really big number, unfortunately humans can’t actually discern that many colors, but the richness and saturation of the colors produces colors that are far more varied than almost anything else you see.
GRABER: The colors are mesmerizing. They glow as they change smoothly from yellow to magenta to turquoise to kelly green. Color Kinetics has used LEDs to design lighting displays for store signs, architectural lighting, sets for rock performances, even a bridge in Philadelphia.
DOWLING: There is a sensor at one end. When the train passes over the bridge, the lights actually chase the train. We’ve done other applications where as you walk by a wall, the wall starts to glow in just phenomenal applications that we have not even begun to dream of.
GRABER: Color Kinetics is also selling light bulbs at art supply stores that change colors and effects with the push of a button.
LEDs have other practical uses, such as lighting heat sensitive material like food, or archival documents, because the fixture remains at room temperature. At a larger scale, LEDs are already taking over in applications such as traffic lights. As Jerry Simmons of Sandia National Lab points out, there is a tremendous loss of energy when a white incandescent bulb is covered with a red filter.
SIMMONS: So you would throw away all the light produced by that bulb, except for the red. With LEDs that are already producing only red, you don’t have to throw any of the light away. So LEDs are ten times more energy efficient than the old incandescent traffic lights.
GRABER: And because LEDs are rugged and can last ten times longer than incandescents, they don’t need to be changed as often. But while color LEDs have had a couple decades of research behind them, the substance used to create white light was discovered only six years ago. The next big challenge is to develop a more efficient, brighter white for residential and retail markets. Right now, white LEDs are only twice as energy efficient as incandescents. They’re also very expensive. But researchers believe they can create white LEDs that are ten times as efficient, and one thousand times as long-lasting, making them cost effective, as well.
Glenn Zorpette is executive editor of Spectrum, a technology magazine for the engineering industry. He says the real signal of the potential of LEDs is the investment by the lighting industry.
ZORPETTE: When you have the established giants, in this case General Electric, Philips and Osram Sylvania all pumping significant quantities of money, of research funding into LED research, something is definitely happening. It would really seem that they see this as an important contributor to lighting in the future.
GRABER: The federal government is also developing millions of dollars to LED research and it’s considering a new research initiative that will allot 50 million dollars per year over the next ten years to make widespread use of light emitting diodes a reality. For Living on Earth, I’m Cynthia Graber.
(The tape of Secretary of Energy Spencer Abraham was provided by Johnson Controls, cosponsor with the United States Energy Association of the 13th
annual Energy Efficiency Forum held June, 2002.)
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