The standard 100-watt light bulb is going away, and its lower-wattage cousins are soon to follow.

U.S. bulbmakers can no longer manufacture the 100-watt bulb as of Saturday -- part of a multiyear push to boost the efficiency of the nation's lighting under a 2007 law signed by President George W. Bush.

For consumers, the law is making the purchase of light bulbs more like an investment choice, with a need to balance higher up-front costs against longer-term electricity savings.

Some of the newest high-efficiency bulbs cost more than $20 each and are designed to last more than 20 years.

"The light bulb is moving from a 60-cent commodity that you throw into your grocery cart to an investment just like a refrigerator or major appliance," said Terry McGowan, director of engineering for the American Lighting Association, an industry trade group. "It costs more money and you expect it to do more, and if you move, you might even take it with you."

Consumers will still see the old-style bulbs on shelves for some time. Lower-wattage incandescent bulbs are being phased out over the next two years. The law allows stores to sell remaining stocks of banned bulbs.

Replacement bulbs using halogen and other technologies are already on store shelves. The incandescent bulb, with its tungsten filament, was a breakthrough in lighting 100 years ago, a vast improvement over the 19th-century designs of Thomas Edison and others. Its shortcoming is that only 10 percent of the energy is converted to light, with the rest lost as heat.

Industry supports change

Lighting industry officials say bulbmakers have supported the federally mandated switch to energy-efficient designs and have already halted production of banned bulbs. Congress' recent action to bar enforcement of the law by the U.S. Energy Department won't turn back the clock, they say.

"The law doesn't change, and we're still complying," said Anne Guertin, a spokeswoman for Osram Sylvania, which retooled its incandescent bulb plant in Pennsylvania to manufacture halogen bulbs that meet federal standards.

The law's ban on standard 75-watt bulbs takes effect Jan. 1, 2013, and a year later for standard 40- and 60-watt bulbs. Thousands of specialty bulbs, including 100-watt incandescents designed to stand up to rough treatment, are exempt from the manufacturing ban. Other exempted bulbs include three-way bulbs and flame-shaped lamps for chandeliers.

For consumers, a trip to the store for bulbs will likely be more confusing and costly because of the array of new, longer-lasting options. New, federally mandated labels offer guidance on lumens, or light output, and long-term cost savings on electricity.

Consumers looking to replace a 100-watt bulb, for example, would look for a bulb with 1,600 lumens. The choice might be a compact fluorescent (CFL) bulb, which uses up to 75 percent less energy. A second option looks like a traditional bulb but has a halogen core that uses 23 percent less energy.

Another emerging contender is the light-emitting diode, or LED, bulb that fits into a standard socket. They are energy efficient and long lasting, but cost more than $20 each. LEDs don't offer an equivalent to the 100-watt standard bulb, but one is being developed, said McGowan of the lighting association.

The Energy Independence and Security Act of 2007 aims to save consumers nearly $6 billion annually on electricity costs by 2015. But some Republicans, including presidential candidate Michele Bachmann, have opposed the law as a restriction on freedom of choice.

Measure may have little effect

In an omnibus spending bill that avoided a federal government shutdown last month, Republicans inserted a provision barring the use of federal funds to enforce and implement the bulb law for nine months.

Though it has caused confusion, that measure may have little effect. The 2007 law still took effect Saturday and manufacturers are still obligated to comply, according to the Energy Department.

"The realistic view in the lighting industry is that everything is going to go as normal," McGowan said. "The plans are made. The shelves are stocked. The products are ready."

At Mohn Electric Co. in Minneapolis, a store that stocks thousands of special-purpose light bulbs, employee Mary Norris said she wasn't sure what Congress intended by the measure.

Regardless, she said, the no-longer-manufactured standard 100-watt bulbs will be available at her store for a long time because distributors tend to stock up on discontinued items.

"I just ordered a shipment last week," she said.

Menards in Eden Prairie on Friday still had lots of 100-watt standard bulbs on shelves, alongside an increasing array of LED, CFL and halogen alternatives.

As Steve Veldman, the store's electrical manager, walked through the light bulb aisle, he passed an empty spot. That morning, the shelf had been filled with 12-packs of old-style 100-watt bulbs -- on sale for about half price.

"Sold out an hour ago," he said.

David Shaffer • 612-673-7090