Tar Sands: Carbon Emissions Higher Than for Standard

More carbon is being released by gasoline and diesel derived from Canadian oil sands than from conventional domestic crude sources, researchers from the U.S. Department of Energy's Argonne National Laboratory said in a report published recently in ACS Environmental Science & Technology.

Generally speaking, fuel extracted and refined from Canadian oil sands will release approximately 20 percent more carbon into the atmosphere than fuel from conventional domestic crude sources, according to a release.

"This is important information about the greenhouse gas impact of this oil source, and this is the first time it has been made available at this level of fidelity," said Hao Cai, the Argonne researcher who led the study, in a release. "Canadian oil sands accounted for about nine percent of the total crude processed in U.S. refineries in 2013, but that percentage is projected to rise to 14 percent in 2020."

The researchers gathered publicly available data on 27 large Canadian oil sands production facilities. Additional carbon impacts related primarily to the energy required for extraction and refining, methane emissions from tailing ponds, and carbon emissions from land disturbance, the study found.

Depending on the extraction technologies (surface mining vs. in situ) and oil sands products (bitumen vs. synthetic crude oil), the carbon intensity of finished gasoline can vary from 8 to 24 percent higher than that from conventional U.S. crudes, the study found.

"It was common knowledge that Canadian oil sand extraction was energy intensive, but no study was able to quantify that intensity with this level of detail and certainty," said Michael Wang, Argonne's leading expert on fuel cycle analysis. "This information will be important for industry and policy makers as they chart a path forward to meet the fuel demands of the U.S., while minimizing the environmental impact of that fuel."