The ambitious programme for replacing about 400 million electric bulbs with energy-efficient, compact fluorescent lamps by 2012 is a noteworthy step in the country's climate change mitigation effort.

The Bachat Lamp Yojna, launched in Visakhapatnam in Andhra Pradesh and Yamunanagar in Haryana last week, has some unique features (besides its massive scale) which sets it apart from other ventures aimed at reducing global warming. It involves the government, the Bureau of Energy Efficiency and private companies, including state-level electricity distribution companies (Discoms) and manufacturers of CFLs.

It moots a novel way of subsidising the sale of CFLs for lighting homesteads; each CFL, costing over Rs 100, will be sold by the Discoms at Rs 15. The remaining cost will be recovered from the sale of certified emission rights (or carbon credits), earned as a result of their use, under the clean development mechanism of the Kyoto protocol on climate change.

BEE will collate the carbon credits accruing to different participating companies and submit them to the global CDM executive board for certification. If the programme succeeds, the environmental benefits will be huge -- equivalent to saving up to 55 million tonnes of carbon dioxide emissions or the closure of four big coal-based power plants. The initial response from the prospective participants is encouraging and some 20 companies have already shown an interest.

A sizable part of the electricity consumed in the country is normally wasted as the bulbs and other electric appliances used in households are inefficient users of power. In the case of incandescent bulbs, only 5 per cent of the power consumed by them goes into lighting, the rest is just converted into heat.

By way of contrast, CFLs consume one-fifth as much electricity to produce the same level of illumination. However, they cost eight to 10 times more, and this deters most people from buying them. This in turn limits their use largely to commercial buildings. The emphasis under the project on breaking this cost barrier is, thus, well placed.

But while it is true that CFLs are more energy-efficient, they contain mercury whose safe disposal is always a problem. And the mercury content is far higher in the CFLs manufactured in India (usually between 3 mg and 13 mg), compared to those made in some advanced countries which have just 1 mg mercury.