"Seventy-three percent of the energy we use in our mill system we produce," says Ann Wrobleski, IP's vice president for global government relations. "We feel like we're the original green industry, if you will." (In developed nations, paper is the third-largest industrial greenhouse gas emitter, behind the steel and chemical industries.)

By adding diesel fuel to the black liquor, paper companies produce a mixture that qualifies for the mixed-fuel tax credit, allowing them to burn "black liquor into gold," as a JPMorgan report put it. It's unclear who first came up with the idea--Wrobleski told me it was "outside consultants"--but at some point last fall IP and Verso, another paper company, formerly a part of IP, began adding diesel to its black liquor and applied to the IRS for the credit. (Verso nabbed $29.7 million at just one of its mills in the final quarter of 2008 for its use of mixed fuel.)