Search Penny Hill Press

Tuesday, July 3, 2012

Canadian Oil Sands: Life-Cycle Assessments of Greenhouse Gas Emissions

Richard K. Lattanzio
Analyst in Environmental Policy

Canadian Oil Sands and Climate Change 

Recent congressional interest in U.S. energy policy has focused in part on ways through which the United States could secure more economical and reliable crude oil resources both domestically and internationally. Many forecasters identify petroleum refined from Canadian oil sands as one possible solution. Increased petroleum production from Canadian oil sands, however, is not without controversy, as many have expressed concern over the potential environmental impacts. These impacts may include emissions of greenhouse gases (GHG) during extraction and processing. A number of key studies in recent literature have expressed findings that the GHG emissions intensities of Canadian oil sands crudes may be higher than those of other crudes imported, refined, and consumed in the United States. The studies identify two main reasons for the increase: (1) oil sands are heavier and more viscous than lighter crude oil types on average, and thus require more energy- and resource-intensive activities to extract; and (2) oil sands are compositionally deficient in hydrogen, and have a higher carbon, sulfur, and heavy metal content than lighter crude oil types on average, and thus require more processing to yield consumable fuels by U.S. standards. 

Selected Findings from the Primary Published Studies 

CRS surveyed the published literature, including the U.S. Department of State-commissioned study in the Environmental Impact Statement for the Keystone XL pipeline project. The primary literature reveals the following:

  • Canadian oil sands crudes are on average somewhat more GHG emission-intensive than the crudes they would displace in U.S. refineries, as Well-to-Wheel GHG emissions are, on average, 14%-20% higher for Canadian oil sands crude than for the weighted average of transportation fuels sold or distributed in the United States; 
  • discounting the final consumption phase of the life-cycle assessment (which can contribute up to 70%-80% of Well-to-Wheel emissions), Well-to-Tank (i.e., “production”) GHG emissions are, on average, 72%-111% higher for Canadian oil sands crude than for the weighted average of transportation fuels sold or distributed in the United States; 
  • compared to selected imports, Canadian oil sands crudes range from 9% to 19% more emission-intensive than Middle Eastern Sour, 5% to 13% more emission-intensive than Mexican Maya, and 2% to 18% more emission-intensive than various Venezuelan crudes, on a Well-to-Wheel basis; 
  • the estimated effect of the proposed Keystone XL pipeline on the U.S. GHG footprint would be an increase of 3 million to 21 million metric tons of GHG emissions annually (equal to the annual GHG emissions from the combustion of fuels in approximately 588,000 to 4,061,000 passenger vehicles); and 
  • the estimated effect of the Keystone XL pipeline on global GHG emissions remains uncertain, as some speculate that its construction would encourage an expansion of oil sands development, while others suggest that the project would not substantially influence either the rate or magnitude of oil extraction activities in Canada or the overall volume of crude oil transported to and refined in the United States. 
Scope and Purpose of This Report 

After discussing the basic methodology of life-cycle assessments and examining the choice of boundaries, design features, and input assumptions, this report compares several of the publicly available assessments of life-cycle emissions data for Canadian oil sands crudes against each other and against those of other global reference crudes. Further, as congressional concern over the environmental impacts of Canadian oil sands production may encompass both a broad understanding of the global resource as well as a specific assessment of the proposed Keystone XL pipeline, the report surveys both the general scientific literature as well as the individual findings of the State Department’s Keystone XL Project Environmental Impact Statement. Finally, as life-cycle assessments have become an influential—albeit developing—methodology for collecting, analyzing, and comparing GHG emissions, the report concludes with a discussion of some tools for policymakers who are interested in using these assessments to investigate the potential impacts of U.S. energy policy choices on the environment.

Date of Report: June 18, 2012
Number of Pages: 31
Order Number: R42537
Price: $29.95

Document available via e-mail as a pdf file or in paper form.

To Order:

R42537.pdf  to use the SECURE SHOPPING CART


Phone 301-253-0881

For email and phone orders, provide a Visa, MasterCard, American Express, or Discover card number, expiration date, and name on the card. Indicate whether you want e-mail or postal delivery. Phone orders are preferred and receive priority processing.

Follow us on TWITTER at or #CRSreports