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Fuel extracted and refined from Alberta, Canada's tar sands has been found to release about 20 percent more carbon in the atmosphere compared to gasoline and diesel extracted from conventional domestic sources, a study has found.
Deriving fuel from the oil sands is an energy-intensive process, and researchers from the US Department of Energy's Argonne National Laboratory, the University of California, Davis, and Stanford University showed that the additional carbon impact of Canadian oil sands was largely related to the energy required for extraction and refining. They used publicly available data on 27 large Canadian oil sands production facilities.
The study results provide further ammunition to environmentalists who have long been maintaining that oil sands are one of the world's dirtiest sources of fuel, and an especially strong boost to activists working to block US approval of the contentious Keystone XL pipeline project, which would transport oil from the tar sands to US refineries.
While oil found close to the surface in the sands can be mined, it still requires heat to separate the oil from sand. Deeper oil sources require even more energy when steam is injected underground, heating the oil to the point when it can be pumped to the surface. The process tends to be more carbon intensive than surface mining, and depending on which method is used, the carbon intensity of finished gasoline can be 8 to 24 percent higher than that from conventional US crudes, the study found.
"Canadian oil sands accounted for about 9 percent of the total crude processed in US refineries in 2013, but that percentage is projected to rise to 14 percent in 2020," lead author and Argonne researcher Hao Cai said in a statement.