The National Wildlife Federation and other environmental groups have been lobbying against the Keystone XL pipeline proposal as a sort of proxy battle against production of crude oil from Canadian tar sands. Robert Hahn and Peter Passell suggest that, as the tar sands will be developed whether or not the pipeline is built, the practical effect of stopping the pipeline project is increased delivery of Canadian oil by railroad instead. Not only does railroad delivery of oil come with its own risk of spills, it is a more costly mode of transportation largely because it takes more energy to move crude oil by rail rather than pipeline. And “takes more energy” means “burns more energy” means more greenhouse gasses and other air emissions during delivery.
Since a pipeline would be the cheapest and best way to deliver Alberta’s oil to market, if the National Wildlife Federation and other groups succeed in imposing some more complicated and costly delivery method then at the margin some production in Alberta will be deterred. The result: U.S. will instead buy the oil that would have come from Alberta from elsewhere, and have it delivered by ocean-crossing tankers. Last I looked oil tankers were not propelled by rainbow juice and unicorn kisses, so those likely alternatives will come with their own set of greenhouse gasses and other emissions.
Assuming the tar sands are developed – and as Hahn and Passell say, “last time we looked, Canada was a functioning democracy capable of making its own decisions” – the pipeline is likely the most environmentally friendly way of delivering the oil to consumers.