The whole Enron deal is 10 years ago. But I think I remember something like what you are talking about, the idea of trading carbon credits.
Don't forget that the whole idea of Cap and Trade came from James Watt. How they hated him for it. They suddenly realized, hey, this could work, and ran with it, only they cut the cap way down. And Carbon credits seems to be a scam from the get go, as we don't know enough to know if any of it works.
I don't know if the Watt proposal was called "Cap and Trade" though. It was one of the really cool ideas of 1981 that got no where.
But I do think Enron would have been very interested in cap and trade. Anything to do with trading energy would have been right up their dark ally. And I am pretty sure they were talking about this when the whole thing went south.
What really bothers me about the whole Enron deal was Paul Krugman's jihad against Bush as an Enron stooge, when I don't believe there was even any evidence that Bush and Lay even met, while Krugman was a flack for Enron for years, and gave himself a pass.