After touching down at San Francisco International Airport after the holidays, I didn't feel so guilty about flying as I had in the past. Or actually, because of optimism for a New Year, reduced gas prices and a third of the seats on my flight staying empty, I didn't even give a thought about feeling guilty.

However, I was landing in San Francisco, one of the most eco-conscious places in America, and the city intends to do its part in making everyone passing through its borders aware of their carbon footprint. Not only is San Francisco the first U.S. city to consider a "congestion pricing plan" for motorists driving its streets, it will also be the first city in the world to let travelers buy certified carbon offsets in its airport.

Starting this spring, SFO will offer self-service kiosks from 3Degrees, a local funder of clean energy and carbon-reduction projects, so that guilty frequent-fliers can punch in their destinations, calculate their carbon footprints, and swipe a credit card to pay for the damage they do. In return, they'd get a receipt listing the projects benefiting from their contribution. Unfortunately, they don't get a tax deduction.

Becuase the project is still in the works, there's no specifics about carbon-offset charges or what programs would get the proceeds, but 3Degrees estimates the cost of offsetting a two-hour trip emitting 1,000 pounds of carbon dioxide per person would be $4, while offsetting a trip to Europe would cost $36. The office of San Francisco Mayor Gavin Newsom would be in charge of picking the programs to reap the benefits -- and 3Degrees gets 30% of each purchase..

Will this program "take off"? I don't think I'll get on board just yet. Besides pinching every penny during this recession, I'd like to have more say about where my money goes and not have Mayor Newsom, however eco-friendly he is, make the decision for me.

Why not install kiosks that let you pick the project you want to benefit? Reading the background info about each program would make me feel more inclined to spend money on this -- and would kill more time while waiting for fog-delayed flights to board. I'm not the only skeptic. In reply to the San Francisco Chronicle article about the kiosks, comments included, "This is the definition of absurd, " "I have never heard of anything so crazy" and "Even if the city wasn't facing a massive budget deficit, this idea would still be ridiculous." And these are from San Franciscans, a typically green bunch!

Good intentions, but wrong format. But if you still believe in the idea of paying to offset carbon dioxide from your flights, you can fly Delta and participate in its carbon-offsets program, the only U.S. airline currently to offer one, or hop a flight in or out of SFO starting this spring and try out one of the kiosks.