When Thomas Edison first showed his filament lamps to the public on Dec 31, 1879, in Menlo Park, California, he said: "We will make electric light so cheap that only the rich will burn candles."

More than 130 years on and he might have said something similar about compact fluorescent lamps being so cheap that only the rich will still use incandescent bulbs.

Since 2008, the authorities have subsidized the use of CFLs, as they want to phase out the use of incandescent bulbs by 2016. About 150 million CFLs are now sold with subsidies in China each year.