Replacing only one light bulb in every American home with an Energy Star bulb would reduce greenhouse gas emissions by 9 billion pounds, or about the amount from 800,000 cars, as reported by the EPA. How many can you replace?
Compared with incandescent bulbs; Halogens use 25% less energy, CFLs use about 75% and LEDs 80% less. They also last much longer than incandescents and will save you $40-60 over the course of their lifetime. There are choices to meet every need. Check out this energysaver guide to bulbs.