| Recently the Intergovernmental Panel on Climate Change of the UN issued strict warning to all nations of the world to cut down on CO2 emission to halt global warming, which otherwise may be devastating. Greenpeace has been spearheading a “Ban the Bulb” campaign across the world. The “bulb” in its campaign is the ubiquitous incandescent bulb that has been illuminating millions of houses for more than a century now. What has incandescent bulb to do with global warming?
In an incandescent bulb the electric current passing through the filament heats it up to about 2500 degree Celsius. The heat excites the atoms in the filament causing it to emit light. In the process, however, nearly 90 percent of the electricity is converted to waste heat, making the bulb highly energy inefficient.
How the CFL works
An alternative to incandescent bulb is the energy efficient fluorescent lamp, which works on a different principle. It consists of a long glass tube fitted with electrodes on both ends. The tube is filled with low pressure mercury vapor and a gas such as argon or xenon. The inside of the tube is coated with a white powder which is a blend of phosphors. When the tube is switched on, electrons emitted form the electrodes excite the mercury atoms causing them to emit ultraviolet light (UV).
The UV light, which is invisible, is then absorbed by the phosphor coating, which reradiates the energy in the form of visible light. Since no heating is involved, a fluorescent lamp requires only about 20 percent of the electrical energy used by an incandescent bulb to produce the same amount of light.
The latest avatar of the fluorescent lamp is the ‘compact fluorescent lamp’ (CFL). They are small, user-friendly and can be fitted into existing bulb holders without the need for additional fixtures. They are available in a wide range of ratings from 5 Watts to more than 60 Watts. Since they yield four to five times more light per Watt compared with incandescent bulbs, a 10 Watt CFL can replace a 40 Watt bulb.
Similarly, 15 to 18 and 20 to 25 Watt CFLs can replace 60 and 100 Watt incandescent bulbs respectively, thus reducing the energy bill on lighting by nearly 80 percent!
CFLs are expensive to buy. However, they have a long life span, ranging form 7000 to 10,000 hours, compared with only about 1000 hours for the incandescent bulb. This fact, coupled with the saving on the energy bill can easily off set the initial expenditure.
Venezuela and Cuba are the first countries to take a bold decision in 2005 to phase out the incandescent bulbs. In February 2007 Australia enacted a law to ban the sale of incandescent bulbs by 2010. The European Union (EU) is considering a similar law. It is estimated that if the existing 3.6 billion incandescent bulbs in use across the EU are replaced by CFLs it will result not only in saving 5 to 6 billion Euros, but also cut down CO2 emission by 20 million tones a year!
Similar legislations are under way in Canada, New Zealand, Netherlands, and some states of USA.
The Indian Scene
The government of India has not issued any official policy in this regard.
The Greenpeace which launched a campaign across India in April 2007 has provided some very interesting statistics in this regard.
Eighteen percent of the electricity generated in India is used for lighting purposes.
The production of incandescent bulbs has gone up from 638 million in 2000 to 2001 to 757 million in 2005-06.
During the same period though, the production of CFL has registered an increase from 6.4 million to 44 million, it still amounts to less than six percent of the total number of incandescent bulbs.
According to Greenpeace, switching over to CFL would help India save 12,000 mega Watts a year, leading to a reduction in the CO2 emission by four percent.
Mercury content
Critics point out that used CFLs during recycling may release mercury, one of the most toxic elements, to the environment. However, according to a report from the General Electric Company it is about four times less than the quantity of mercury released during coal burning to produce the amount of electricity required to use an incandescent bulb. Hence, switching over to CFL would also indirectly reduce the mercury load in the environment. | 
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