Skip to main content

Tank cars at Canadian Pacific’s Port Coquitlam yard east of Vancouver.DARRYL DYCK/The Globe and Mail

The battle over the best way to export Canada's oil has encountered a new question: who uses the least energy to move a barrel of oil?

This week, TransCanada Corp. argued that those in the United States considering approval of the Keystone XL pipeline should see it as a cleaner alternative to the trains that are increasingly carrying Canadian crude to market.

"For every mile you move a barrel of oil by rail, you emit three times the [greenhouse gases] that you do by moving it by pipeline," Alex Pourbaix, TransCanada's president of energy and oil pipelines, told a New York audience at a conference Thursday, according to the Canadian Press.

The U.S. State Department, in some of its earlier documents, has included similar figures.

But is rail really much worse? The rail industry – and the State Department itself, in recent updates – says no. In fact, according to Canadian National Railway Co., trains can move heavy oil far more efficiently than pipelines. In a 2010 presentation, CN compares the estimated grams of carbon dioxide emitted in moving a barrel of bitumen one kilometre.

For a pipeline, it's 7.7. For rail, it's 2.9.

"CN has a very positive environmental story," spokesman Mark Hallman said in an e-mail.

But how could CN and Mr. Pourbaix come to such radically different conclusions? In part, it comes down to the peculiarities of moving heavy oil.

For light oil, pipelines have significant advantages. But much of the oil flowing through Keystone XL will be heavy crude from the oil sands – and with heavy oil, rail may be better.

Bitumen extracted from the oil sands is so thick – it's thicker than peanut butter – that it can't flow through pipelines on its own. Instead, it must be thinned with so-called diluent to make a product called diluted bitumen, which is typically 70 per cent bitumen and 30 per cent diluent. That diluent must then be carried back to the oil sands to thin the next batch of bitumen, which effectively doubles the amount of pipeline transport needed to move a single barrel of bitumen.

Trains, on the other hand, are able to carry undiluted bitumen in cars that can be heated to make the bitumen flow, reducing the number of barrels that need to be moved around. That's one advantage.

Another: diluted bitumen is hard to pump through pipelines. It's more dense than light oil and vastly more viscous, so it creates more friction as it moves. That, in turn, means it takes far more horsepower to get it through a pipeline. A pipeline engineer contacted by The Globe and Mail calculated that, compared to light oil, it would take 100 per cent to 130 per cent more energy to move a barrel of diluted bitumen through a pipeline the size of Keystone XL.

In a train, the viscosity of oil makes virtually no difference to the ability to move it.

"Pipelining heavy oil is like pushing a McDonald's milkshake through a straw, whereas one of the issues with rail cars is that an empty one will actually move from just the wind – there is almost no friction from a steel wheel on a steel line," said one executive involved with moving oil by rail.

For that reason, CN has calculated that trains are the second-most efficient way of moving bitumen – worse than ships, but better than pipelines.

Even the most recent documents from the U.S. government offer a much more restrained look at the emissions differences. The State Department looks at two alternatives to Keystone XL: one that would use trains to get oil to Oklahoma, and then pipelines to the Gulf Coast. The second would use trains to get oil to Prince Rupert, on the B.C. coast, and then tankers through the Panama Canal to the Gulf Coast.

The rail-pipeline scenario would produce 8 per cent more emissions than Keystone XL, the State Department calculated. The rail-tanker scenario would produce 17 per cent more. But the comparison is based solely on the transport of diluted bitumen – it does not determine the savings from trains moving straight bitumen. The State Department also did not examine the emissions from delivering oil by trains all the way to the Gulf – an option that some companies are already using.

The State Department pointed out, however, that the rate of spill incidents is 34 times higher for trains, relying on data compiled by Diana Furchtgott-Rott at the Manhattan Institute. Pipelines also spill less crude. Comparing numbers maintained by the Association of American Railroads and oil pipeliner Enbridge Inc., trains in the U.S. spill nearly seven times more of the hazardous product they carry, on a per-unit basis, than Enbridge pipelines.

Your Globe

Build your personal news feed

Follow the author of this article:

Check Following for new articles

Interact with The Globe