Cost of Saving the Climate Meets Real-World Hurdles

Large corporations have bought offsets by the millions. Last month, one utility, American Electric Power, agreed to offset about 4.6 million tons of carbon dioxide by paying for projects that reduce methane -- a powerful pollutant -- seeping from farm manure.

For individual consumers, an offset can be a tempting alternative to a radical lifestyle makeover. People concerned about climate change could sell their cars and cover their roofs with solar panels. Or, on an offset site, they could become "carbon neutral" with a click.

"That means I . . . keep my current gas-guzzling car," said Brian Schilling, an Arlington writer who paid the company TerraPass about $108 to offset his home and auto for a year, "and make up for it some other way."

But scientists and academic researchers have begun to warn consumers that it's not that simple.

"Companies can basically sell whatever they want," said Anja Kollmuss, who helped compile a report on the industry for the Tufts University Climate Initiative. "I didn't find downright fraud. I think most companies want to do the right thing.

"Quite a few just don't know the industry very well and just don't know how complex the issues are."

One case in point: trees. Some offset vendors promise to plant them, saying that they naturally draw carbon dioxide out of the air.

But researchers say that it's hard to know what is being offset because the impact of a tree depends on species, location and other factors. If the tree burns or is chopped down, the benefit disappears.

Even more head-spinning are the questions about "renewable energy certificates" from wind farms and solar plants, certifying that they made a certain amount of clean energy.

Offset companies buy these pieces of paper. Then, they use them to claim credit for pollution "avoided" -- reasoning that they helped produce energy that would otherwise have come from a polluting coal or natural-gas plant.

Some of the money paid for these certificates stays with the offset vendor or with a middleman. The rest usually winds up with the energy project's builder or the utility that buys its electricity. In some cases, this can amount to something like a donation to a for-profit company: American Electric Power, which sold an undisclosed amount of certificates from wind farms last year, earned more than $1 billion in profit.

Some environmentalists balk at this. If the certificate is bought only after the energy is produced, they wonder, how can an offset vendor know the energy wouldn't have been produced anyway?