COLUMBIA, Mo. - Consumers may feel sticker shock when paying $4 to replace that burnt out 50-cent incandescent light bulb, but that pricey new bulb can last for years.

"While Compact Fluorescent Lamps (CFLs) cost more than incandescent bulbs, they last up to 10 times longer and use about one-fourth the energy. CFLs are the kind of light bulbs people take with them when they move," said Barbara Buffaloe, University of Missouri Extension associate.

Efficiency standards under the Energy Independence and Security Act of 2007 will require a phase-out of sales of conventional incandescent bulbs beginning in 2012. By 2014 those bulbs will no longer be sold, giving way to CFLs and other more energy-efficient bulbs.

CFLs can not only lower your electric bill, their longer lifetime should more than make up for the higher price.

Government cost-comparison figures indicate a 167-day lamp life for a 100-watt incandescent bulb, compared to a 1,642-day lamp life for CFL bulb, translating into an estimated $63 savings.

First-time buyers may want to go to a hardware store or other retail outlet where they can ask questions to make sure they are getting the right bulb.

Consumers should look for the Department of Energy's Energy Star label on the packaging. The Energy Star program sets strict criteria for lamp life, energy savings, start time, color and brightness. Bulbs with the Energy Star label also come with a limited two-year warranty.

Another thing to consider when buying a CFL is its light output. "You should compare the wattage of incandescent lamps with CFL wattage that provides similar light levels," Buffaloe said.

For example, a 25-watt CFL bulb compares with 100-watt incandescent bulb in light level. Retailers should have charts to make such comparisons.

Also check the bulb's Kelvin (K) rating. CFLs with a lower K rating (2,700-3,00K) give off a soft light similar to incandescent light. Bulbs with a higher K rating (3,500-6,500K) give off a cooler white or bluish-white light identified as bright white or daylight.

Check to see if your light switches are set for dimming. If so, be sure to buy CFLs with dimming indicated on the packaging to avoid an early burnout.

CFLs contain a small amount of mercury, about five milligrams, roughly equivalent to the tip of a ballpoint pen, Buffaloe said.

No mercury is released when the bulbs are in use and no health threat exists from an unbroken bulb.

Do not dispose of your CFLs in household garbage if a hazardous waste facility is available. If there's no such facility, place the bulb in a sealed plastic bag before putting it the trash, she said.