The brightest bulb in most homes for more than a century is fading toward darkness this year as California turns out the light on the century-old incandescent.

Beginning Jan. 1, the state began phasing out certain energy-sucking bulbs, federal standards the rest of the country will enact next year.

Manufacturers will no longer make the traditional 100-watt bulb and stores will eventually sell out of current supplies. Consumers will have to choose from more efficient bulbs that use no more than 72 watts, including halogen incandescents, compact fluorescents and light-emitting diode, or LED, bulbs.

"These standards will help cut our nation's electric bill by over $10 billion a year and will save the equivalent electricity as 30 large power plants," said Noah Horowitz a senior scientist with the Natural Resources Defense Council. "That translates into a whole lot less global warming pollution being emitted."

The change is part of the federal Energy Independence and Security Act that President George Bush signed in 2007, to reduce energy use and greenhouse gas emissions. California was allowed to adopt the national standard one year earlier.

The act requires new bulbs to use 25 to 30 percent less energy beginning in 2012 nationally — starting with the 100-watt bulb. By 2014, other incandescent bulbs, including the 75-, 60- and 40-watt, will also be phased out across the country.

Some specialty bulbs, however, will continue to be available. Consumers will still be able to get smaller lights such as yellow bug lights and aquarium bulbs.

Light bulb manufacturers said they haven't gotten any reports of customers hoarding 100-watt bulbs yet, though that may change once supplies begin to dry up and word gets out.

Nick Reynoza, manager at Royal Lighting in Los Angeles, said it's a shame the transition comes at a time when alternatives are so much more expensive.

"It's not really an option — you have this or you don't get anything," he said. "The options are more expensive. Four incandescents are $1.00, the halogens are $5.99 and the LED are like $20."

While conservation groups back the change and the lighting industry has invested heavily in new technology, not everyone supports the law. Rep. Joe Barton, R-Texas, who could not immediately be reached for comment, reintroduced legislation this year to repeal the law.

"People don't want Congress dictating what light fixtures they can use," said Rep. Barton on his website. "Traditional incandescent bulbs are cheap and reliable."

Adam Gottlieb, spokesman for the California Energy Commission, acknowledged that the change has resulted in a "great deal of hue and cry" on some blogs as well. Recent postings have included the titles "More dim bulbs: California banning 100-watt incandescent light bulbs" and "More evidence that California is nuts."

Gottlieb, however, said it was not a ban and that consumers can still buy whatever bulbs they want as long as they meet the new standards.

"After 130 years Tom Edison's old-fashioned light bulb is getting a 20th century makeover," he said. "The simple truth is consumers will save money."

The newer bulbs are more expensive than incandescents, but supporters of the technology say they last so much longer that there is a financial savings in the end. For example, while incandescents provide as much as 2,000 hours of light, compact fluorescents can provide light for six times longer.

Incandescents, which create light by passing an electric current through a tungsten wire filament, also waste 90 percent of the electricity they use as heat instead of light. Fluorescents, by comparison, apply an electrical current to different types of phosphers to produce light and produce less heat.

But fans of the traditional bulb say they provide a softer, more natural light and turn on more quickly. Michael Petras, president of GE Lighting, said the industry is aware of the shortcomings and is working to refine the technology.

"We've got compact fluorescents that look like incandescents," he said from the company's headquarters in Cleveland. "We have a product coming out this spring that's a hybrid of compact fluorescent and halogen that will provide energy savings and a better start up time."

Australia was the first to begin phasing out incandescents beginning in 2009, followed by the European Union, the Philippines and Argentina, said Petras. Mexico and Brazil are expected to follow the U.S.