Archive for Sunday, October 8, 2006

Bright future

Toplikar: LEDs, silicon offer options for efficient high-tech illumination

October 8, 2006


Flipping the switch, I got a surprise - did something explode? Glass shards, thick and jagged, were everywhere, emanating from the center of the kitchen.

For no apparent reason, the overhead bowl-shaped light cover had crashed to the floor.

I also noticed only one of the two light bulbs was working overhead - an old-fashioned, 75-watt incandescent light bulb I had put up last month.

As I swept up, I knew I'd be getting a new light fixture - and wondered if I should consider installing solid state lighting for the kitchen.

Trading out

For the last year or so, I'd been methodically trying to replace burned out incandescent lightbulbs in my house with more energy-efficient lights.

Lights contribute to about 20 percent of an electric bill, so I'd been trying to save money and do my small part to reduce energy consumption and reverse global warming.

Now my basement and garage have those weird-looking spiral-type, screw-in compact fluorescent lights.

But I've been a little reluctant to trade out the regular bulbs in rooms where my family spends more time. That's because I'm afraid the fluorescents will make everything seem a little off, color-wise. I also read there are trace amounts of mercury in fluorescents, so you need to be careful with them.

Enter the latest technology: solid state lighting.

Most people are familiar with solid state lighting in the form of semiconductors, such as light-emitting diodes, or LEDs, which glow when an electric current passes through them.

In the last few years, more and more LEDs have been showing up in flashlights, outdoor lights, Christmas lights and accent lights.

Tom Glavinich, a KU associate professor of engineering.

Tom Glavinich, a KU associate professor of engineering.

Getting brighter

"In a small concentrated beam, they're fine," said Tom Glavinich, a Kansas University associate professor in civil, environmental and architectural engineering, who has taught classes in lighting. "But if you're just trying to replace a standard lamp, in a table lamp or a floor lamp, that's not going to work right now."

Glavinich told me that my overhead kitchen light couldn't be replaced now with a cheap, effective LED light.

But if I want a little cove lighting, a little glow around the cabinets or some interesting accents, LED lighting would work, he said. Although white LEDs are available now in screw-in bulbs, the color tends to be "cooler" and more bluish, like a white fluorescent.

I did find a few LED screw-in lights online - cost: $25 to $30 each - but the brightest ones only put out about as much light as a 25- to 30-watt bulb. On the good side, they essentially last forever - about 30,000-plus hours, compared to about 750 hours for a traditional bulb. And they take only about 5 watts of electricity.

One leading LED manufacturer, Permlight, does offer some overhead recessed can light fixtures that produce about as much light as a 60- to 75-watt incandescent bulb.

They also burn about 30 percent less electricity than fluorescent bulbs and 80 percent less than incandescent ones. The tradeoff is they're expensive: about $140 for one six-inch recessed can fixture.

Northern lights

The cost of solid state lighting could fall considerably in the coming years, thanks to a product being developed in Canada.

I called Howard Tweddle, who is with Group IV Semiconductor Inc. in Ottawa, Ontario. The company recently announced it was starting a project to make solid state lighting out of cheap, plentiful silicon.

It's a three-year project to develop technology that's just now coming out of the lab, Tweddle said. The effort is being funded by EnCana, one of the largest natural gas suppliers in North America.

"Silicon is actually the workhorse semiconductor material that is used in all, virtually all, integrated circuits that you see in your computer or your television or your cell phone or whatever," Tweddle said.

In its natural state, silicon is a poor emitter of light. So most LEDs are made of more expensive compound semiconductors that more readily produce light.

But if silicon is structured in very, very tiny crystals - called nanocrystals, each one about a millionth of a millimeter across - the special silicon takes on properties that allow it to generate light directly from electricity, he said.

"Although that principle has been understood in the lab, it's taken a long time for people to come toward actually building something like that," he said. "We expect to have demonstration prototype lamps about three years from now.

"You're not going to see it in your hardware store tomorrow."

The company looks to produce screw-in type lights that homeowners would be able to use in place of traditional incandescent bulbs.

"People are going to need to be able to pick it up, screw it in and be familiar with it," Tweddle said. "What will drive the industrial design is something that is comfortable and acceptable for people who have to use it."

Naked light

"Dad, I keep stepping on glass," Katy told me as we passed each other in the kitchen.

"Sorry, I thought I got all the pieces," I told my daughter.

Not only did I need a broom, but I still needed to get a new fixture. That old incandescent 75-watt bulb kept gobbling electricity.

While I'm at the hardware store, I'll probably also get a fluorescent bulb to try out in the kitchen.

It won't be solid state. It might put off a blue tint. But it might help save the planet - and keep my winter electric bill from exploding.


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