If so, Duke Energy wants to soothe your environmental conscience. Soon, you'll be able to pay the utility to offset some or all of the carbon dioxide produced by your life.

Duke would turn that money over to green projects, such as planting trees or building wind farms. The offsets would be designed to balance carbon dioxide produced from day-to-day living and special events, such as taking a flight.

Drive, turn up the air conditioner, use the Internet, exhale -- it all produces carbon dioxide one way or another. The average U.S. driver, for example, contributes about 12,000 pounds a year from exhaust, Duke said.

An unnatural buildup of carbon dioxide is blamed as a cause of global warming, which scientists fear could melt polar ice and cause massive flooding and dangerous weather. Coal-fired power plants, which provide Duke with most of its power, are among the biggest producers of the gas.

Duke and regulators have yet to work out the details of the voluntary program, including its cost. But Georgia-based green marketing firm Sterling Planet, mentioned as a possible partner, said offsets come in two general forms: paying to promote renewable electricity production (such as those wind farms) and paying to support activities, such as planting trees.

Duke's announcement on Monday is part of a continued greening-up for the utility as it tries to counteract an environmental image problem. Duke has been battling with environmentalists for more than two years over a coal-fired power plant project in the Blue Ridge foothills at its Cliffside plant.

The practice of offsetting carbon dioxide has developed a high profile as Hollywood celebrities and companies, such as Ben and Jerry's, have publicized their efforts to cancel out their own carbon dioxide-producing behavior.

Duke's offset proposal amounts to an expansion of the existing NC GreenPower program, which allows N.C. utility customers to buy renewable energy, including wind and solar power.

Homeowners buy green power in increments of $4, tacked on to their monthly bill. It would cost the average homeowner more than $40 extra per month to use only green power.

Critics of offsets say they can be more about green fashion than about actually reducing carbon dioxide emissions.

Roy Cordato, vice president of research for the John Locke Foundation, a libertarian-leaning public policy watchdog group in Raleigh, is a skeptic.

"I can see why Duke wants to do it -- it's good public relations. And it might make your wallet lighter," he said. "But let's not pretend it's going to make the seas rise more slowly off the coast of North Carolina in our lifetime or your children's lifetimes."

Keith Trent, a Duke group executive and policy and regulatory officer, said the program will help reduce carbon dioxide, even if only a little. And it will also educate customers about their individual contribution to the sum total of emissions. The utility would not profit from the program.

People can buy offsets online through various companies, such as Sterling Planet. Mel Jones, the company's chief executive, said that for roughly $700 a year, the average Carolinas power customer could offset their entire carbon footprint.

Your carbon footprint

A family of four that lives in an all-electric home, has an average Carolinas power bill and drives a car that gets 20 mpg produces about 28,600 pounds of carbon dioxide a year, according to the U.S. Environmental Protection Agency carbon calculator. That assumes the family has been environmentally conscious by recycling newspaper, plastic bottles and aluminum and steel cans, which cuts the emissions by nearly 2,400 pounds. But if their car got 30 mpg, it would decrease their carbon footprint by another 4,000 pounds.

Check your own carbon footprint at http://epa.gov/climatechange/emissions/ind_calculator.html

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