Sep 29, 2008 — Last week, we reported that, for the first time in the U.S., the right to emit large amounts of greenhouse gases went up for auction. Now, power plants across the Northeast have to buy a credit for each ton of carbon dioxide they emit. This makes these emissions more expensive and encourages the use of clean technologies. But power plants aren't the only ones who can buy carbon credits. John Sheehan, with the Adirondack Council, says the green group put in two bids for 2,000 credits before the gavel fell on Friday. Jonathan Brown asked him why.