In a draft assessment of the proposed Keystone XL pipeline, consultants for the U.S. State Department judged that building it would have no significant . Why? Because the analysts assumed the tar sands oil would find a way out with or without the new pipeline.The U.S. Environmental Protection Agency does not agree.to carry an additional 830,000 barrels of tar sands oil per day is vital to expanded production of the tarry crude in Alberta. The EPA contends that the analysis by State got the economics all wrong. In particular the consultants were too optimistic about the ease with which the oil could be moved by railroad--an alternative already in use. But such tar sands oil transportation alternatives can more than triple the cost of moving crude. State's report also neglected to consider the potential for congestion on the railroads with an uptick in oil transport, EPA contends. Of course, from a greenhouse gas perspective, transport by pipeline results in fewer emissions than transport by rail, truck or barge.The bottom line, from a : "oil sands crude is significantly more [greenhouse gas] intensive than other crudes, and therefore has potentially large impacts," wrote EPA's Cynthia Giles about the State Department's attempts to assess the full implications of Keystone. "Lifecycle emissions from oil sands crude could be 81 percent greater than the average crude refined in the U.S.," a difference that can grow "depending on the assumptions made."