the idea behind carbon credits is that if the government institutes a carbon emmissions tax companies would be able to buy carbon credits to offset their emmisions and lower their tax hit. Buying these credits is essentially betting on the fact that this will happen.
With the economy being what it is, as well as growing concerns over energy independence and energy prices overall the chances of such a law being passed in the near future is low. All the GOP candidates have committed that they will NOT pass such legislation. Normally politician promises are worth about as much as pre-used toilet paper, but considering how strongly all oil / coal / natural gas companies oppose such legislation they are probably telling the truth.
My opinion is that by the time the economy recovers enough to entertain such legislation that some new idea will be more likely.
I'd take the money and invest it elsewhere. If you like energy plays natural gas companies are really cheap right now due to the record low price of natural gas, something that will undoubtedly change if you keep a long-term focus.