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That light in the tunnel

india Updated: Oct 19, 2009 18:16 IST
Prasanto K Roy

Tech
LED spots and floods use clusters of 1-watt white LEDs, such as this 9W spotlight (left) with nine

LEDs and a motion sensor, (see glaciallight.com).
Step out of your house and look around. There are thousands of tiny bright lights, on balconies, trees and shops. You’ll find them across the world this weekend. Diwali is a public holiday in a half-dozen Asian countries. You may not find firecrackers everywhere (even Indian states now frown on them), but in dozens of countries across the world, the common thread is a string of Chinese-made LED lights.

The LED (light-emitting diode) isn’t new. It was built in the 1920s by a Russian radio engineer, though you could buy them only from the 1960s onward, and those were dim and red. Modern LEDs are bright and span a range of colours. And you can now buy bright white LEDs – making them great for not just indicator or Diwali lights, but as full-fledged light sources. LEDs use electroluminescence, where a material emits light when an electric current passes through. Old lightbulbs use incandescence – they emit light when heated up, which wastes lots of power as heat. LEDs have a lot going for them. They’re tiny, consume very little energy, last a long time, are robust and switch on instantly. (Mercedes discovered that using them in brake-lights improved reaction time by a third of a second, a crucial benefit for safety.)

LEDs are everywhere. In the past two years, they’ve replaced most traffic lights in Delhi and other major cities. Guess why? Not because they’re ultra-bright and more visible in bright daylight, or because they draw less power. But because they last very long. Regular light bulbs require a “preventive” replacement every six months. Their LED substitute lasts five to ten years, paying for itself many times over, and doesn’t ‘fuse’ in one go. Individual LEDs will fail, giving ample warning when it needs replacement.

The traffic light is a great example of the LED’s incidental benefits – high visibility, low power draw. Even if government departments don’t care about energy bills, the switchover to LEDs makes a huge impact in power-starved cities, helping ensure high traffic-light uptime. More interesting was the discovery that because these lights consumed so little electricity, you could power them through a solar panel and truck battery – making it very easy to set up a traffic light system or flasher in new or isolated locations sans electric cabling.

Another place where the LED has replaced the old lightbulb is the pocket torch. Nokia first added an LED torch to a cheap mobile phone in 2004. The useful little India-inspired addition was a hit. Intex now has a mobile phone with a five-LED torch. Today’s camera-phone inevitably sports a bright little LED flash.

Then came the little flashlights, mostly with five or more white LEDs, powered by three AAA batteries. Today, the state of the art is an ultra-bright one-watt white LED torch. Many use two or three batteries (Philips, Rs 500, Eveready, Rs 125) but last month I picked up a half-dozen of these, each powered by a single AA battery.

Light Emitting Homes
What’s next in 2010? Regular household and commercial lighting, of course. Many companies have launched LED lighting fixtures, and even replacements for bulbs or tubes – these plug directly into existing sockets. They’re still expensive, even though they last many times longer than even CFLs or tubes, and draw less power. So LED lighting is mostly seen where electricity is really in short supply and where their long life is important: in aircraft, ships, automobiles and portable electronics.

Here’s some things we’ll see in 2010: More LED torches at Rs 100. LED luminaires for domestic lighting. A simple 6W LED bulb that plugs into your light socket, with the same light output as the 60W lightbulb it replaces... it would be 50 times more expensive at Rs 500, but last ten times longer, and pay for itself seven times over in power saved (and you wouldn’t replace the bulb in ten years).

With all our energy crisis and power outages across the country, Diwali shows us the way to the light at the end of the tunnel... which is, of course, an LED.

The author is green evangelist at CyberMedia, publisher of 15 specialty titles such as Dataquest. pkr@cybermedia.co.in , twitter.com/prasanto

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