A new study by the National Academy of Sciences found that "pipelines carrying heavy Canadian oil sands fuel are at no greater risk of a spill than those running conventional crude."
Elana Schor calls the findings a blow to the case against the controversial Keystone XL pipeline:
The NAS study deals a blow to one central safety argument made by opponents of the $5.3 billion Keystone XL link -- that the heavier chemical components of so-called diluted bitumen make it more dangerous to ship -- but made no attempt to address critics' second and more prominent concern, that a leak of oil sands crude would pose unique challenges during cleanup as well as unique risks to marine environments. That narrower mission gave environmentalists an opening to shrug off NAS's conclusion as inconsequential in their anti-KXL push.
Lisa Song at InsideClimate News explains why tar sands spills are harder to clean than conventional crude oil:
The issue is important because dilbit behaves differently from conventional crude oil when it spills into water. A 2010 dilbit spill in Michigan's Kalamazoo River is still being cleaned up nearly three years later. Unlike conventional oil, which usually floats on water, dilbit is composed of bitumen—a heavy crude oil—and light hydrocarbons used to thin the bitumen so it can flow through pipelines. During the Kalamazoo spill, the light chemicals gradually evaporated, leaving the bitumen to sink into the riverbed.
Claire Thompson at Grist makes a good point that pipeline leaks are a concern regardless of the oil type:
Of course, calling tar-sands pipelines no riskier than other oil pipelines isn’t exactly a huge comfort. From 1990 to 2011, more than 110 million gallons of oil spilled from U.S. pipelines. The question is not just whether there’s a high chance Keystone XL could leak, but what the consequences would be if — more like when — it did.
Following the recent disaster in Lac-Mégantic, Quebec, in which a train carrying oil derailed and exploded killing 50 people rekindled the debate over whether we should be shipping oil via pipelines or rail.
As I wrote at the time, and have mentioned before, when we consider this question in the context of global climate change, this rail or pipeline debate is a false choice. As the math of global warming makes clear, fossil fuel companies have discovered more oil and gas than is safe to burn. In other words, we simply can not burn all of the fuels we've discovered. Rather than building new pipeline infrastructure to make it easier to transport oil, we need to be working towards policies to leave these fuels in the ground.