The Hindu Business Line : LED by innovation

Are electricity costs pinching your wallet? Do you clench your teeth every time your child leaves a light switched on unnecessarily in an empty room? Take heart, for innovation is around the corner. Await the conquest of the LED.

LEDs or Light Emitting Diodes have found attention in the press across the world. But in India, they are slowly gaining acceptance with manufacturers who hope that, in time, users would buy in to the concept.

The LED, an electronic component that emits light when current is passed through it, is an energy-efficient lighting source. Though it is still in the nascent stage of commercial application, the efficiency it gives clearly indicates that it can make other forms of light sources obsolete for certain applications.

LEDs, which have begun lighting up lives in villages in remote parts of the world, could soon shoo away darkness in our country, as well. The pubic sector Keltron Crystals Ltd recently introduced, in northern parts of Kerala, LED-based home lanterns that give out light sufficient for carrying out household tasks during a power failure.

The technology

LED is used as an indicator in electronic gadgets and equipment as it consumes low power. Besides, its smaller size, compared to incandescent bulbs, helps save space.

LEDs are currently used in cars and two-wheelers in tail lamps and in turn-light indicators. Indian Railways uses LEDs for signals since the life of the lamp is relatively higher.

It is also used in parking lamps of locomotives. LEDs come in different colours such as red, yellow, blue, green orange and white.

LED is a semiconductor component that can emit light when current is passed through it. Most of the power applied is converted to light with a small amount wasted as heat.

Compare this with incandescent lamps, the ones we use at home, where 85 per cent of electrical energy is converted into heat and only 15 per cent is used to make the lamp glow. In an LED, the amount of power used to convert into light, not heat, is nearly 99 per cent.

The LED is highly voltage-sensitive. It can tolerate current only in a minimum range (from 100 milli ampere at 3 volts to 480 milli ampere at 3.6 volts). So connecting DC (direct current) voltage from battery directly to the LED is not recommended. Instead, special driver circuits are used to help draw a fixed, direct current.

Also, using such circuits along with software makes it possible to adjust the brightness of the lamp as required. This not only saves power but also greatly enhances the life of the LED.

The lantern

In the LED lantern, the basic power source is a low-maintenance battery (6 volts and 4.5 ampere hour capacity).

The battery is charged periodically from the wall plug through a charger circuit or from a solar panel. Since the lamp works in its ‘full bright’ position for about 30 hours, charging it once a month may be sufficient for standby purposes, says the Chief Executive of Keltron, U.V. Praveen.

The maximum power consumption of the lantern is 1.2 watt. In the ‘intermediate’ mode it can work for 100 hours and in ‘dim’ mode it can operate for 200 hours.

The low cost of electrical energy consumed by the lantern using white LEDs as the light source could well be its selling point in India. Keltron intends to promote the lantern as an energy efficient and eco-friendly alternative to rechargeable emergency lamps, table lamps and bedside lamps, candles and also for outdoor use to some extent.

Why the lantern?

Keltron, which pioneered the manufacture of piezoelectric quartz crystals besides supporting electronic needs of public and private sectors across the country since inception in 1976, began witnessing a decline in market share after the economy was opened up in 1990s.

It had to resort to various strategies, including diversification, to counter the fall in revenues.

As part of its initiatives to generate additional income and also to fulfil its social commitments as a PSU, Keltron entered into an technology agreement in January this year with Thrive Energy Technologies based in Hyderabad.

Thrive targets rural and impoverished areas in Orissa, Andhra Pradesh, Maharashtra, Afghanistan and Kenya for providing LED-based lighting.

“The cost of electrical energy consumed by the LED lantern is less than three paise for one hour of continuous lighting in ‘full-bright’ mode,” says Praveen.

The LED Lantern manufactured by Keltron is currently sold at factory outlets in a few places in Kerala. Gradually, the product will be made available across the country, he says.

According to industry experts, the emerging LED technology could make compact fluorescent lamp (CFL) obsolete in about five to six years.

The LED evolution

The efficiency of LED is getting better by about 20 per cent every six months as Governments all over the world are heavily funding research to find a safe, energy-efficient and economical substitute for conventional lamps.

The life of the LED is close to one lakh hours while that of CFL and incandescent lamps is 6,000 hours and 1,000 hours, respectively.

However, normal LEDs emit ultraviolet radiations that are harmful to health, especially when the lamp is kept close to the user.

The LED home lantern has light spectrum free from harmful ultraviolet radiation, Praveen says, adding that it has very minimal colour distortion.

The battery is expected to last three years. Also, in the case of incandescent lamps, the heat generated plays a role in adding to the load of the air-conditioning units, eventually consuming more power.

Since the power consumption by LED lantern is comparatively lesser, it is ideally placed to receive power from a solar energy source for recharging.

“Our future products include 2W home lights, LED street lights and 3W LED room lights working directly on 220V mains supply which we plan to introduce in the next few months,” says Praveen.

tmurrali@thehindu.co.in

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