But even as they're cutting utility bills and reducing greenhouse gas emissions, the bulbs are also creating a new environmental headache.
Compact fluorescent lamps, or CFLs, contain a small amount of mercury, a potent human toxin that is federally regulated as hazardous waste.
As used bulbs are thrown away, tons of mercury could eventually find its way into the environment.
Break a CFL in your home and the U.S. Environmental Protection Agency advises that you clear people and pets from the room, open the windows and shut off the furnace blower before tackling the cleanup.
State and federal regulators say the answer is recycling for all household CFLs. But recycling programs can be scarce and inconvenient for consumers.
The Maryland Department of the Environment says fewer than half of the local jurisdictions in Maryland recycle CFLs.
"I have a bucket of bulbs in my basement, and they're going to stay there until they do make it easier," said Brad Heavner, who is state director for Environment Maryland, a public interest advocacy group.
National retailers, which sold most of the 300 million CFLs purchased last year, generally do not take them back for recycling. "We think they should, and we're working on them," said Paul Abernathy, executive director of the Association of Lighting and Mercury Recyclers, which represents the 20 largest commercial mercury recyclers in the nation.
Because CFLs consume a quarter of the power and last six to 10 times longer than incandescents, the twisty bulbs are the darlings of energy conservation programs.
The U.S. Environmental Protection Agency says that if every American household replaced just one incandescent bulb with a CFL, the energy saved could light more than 3 million homes, or eliminate greenhouse gas emissions equivalent to taking 800,000 cars off the road.
Once too clunky and costly to be very appealing, they have become better and cheaper in recent years, and consumers have responded.
Wal-Mart has promoted CFLs, and they have grown from 5 percent of household bulb sales in 2005 to 16 percent in October, said company spokeswoman Tara Raddohl. But the company had disappointing consumer response from recycling events and has chosen to pressure manufacturers to reduce mercury content rather than implement large-scale recycling programs at its stores, she said.
State and local governments have begun to mandate their use in public buildings, both to save energy and to respond to political pressure for action to curb global warming.
But what do we do when they finally do burn out?
Under federal law, large users of fluorescent bulbs and tubes aren't permitted to send them to municipal landfills. The bulbs must be recycled or sent to designated hazardous waste facilities.
Smaller businesses and households are exempt, but the EPA urges consumers to recycle spent CFLs so the mercury, glass and other components can be recovered.