When you are at the hardware store, shopping for replacement bulbs, don’t reach for the cheapest option. Old fashioned incandescent bulbs are generally cheaper off the shelf than compact florescent lights (CFLs), but will cost you and the planet far more in the long run.
CFL’s last six to fifteen times longer than incandescent bulbs, use less energy, and give off less heat. They do need to be recycled properly, as they contain small amounts of mercury. The City of Cape Town ‘Smart Living Handbook’ recommends that you wrap a CFL bulb in a plastic bag before throwing it away and most shopping centres provide customers with a CFL recycling box, in which they can dispose of their bulbs.
Source: the Enviropaedia