The first section of this report discusses the basic methodology of life-cycle assessments and examines the choice of boundaries, design features, and input assumptions. The second section of the report compares several of the publicly available assessments of life-cycle GHG emissions data for Canadian oil sands crudes against each other, against those of other global reference crudes, and against those of other fossil fuel resources. The third section examines some of the specific findings of the Department of State’s commissioned study for the Keystone XL pipeline. 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.
From the Congressional Research Office in the U.S.: Canadian Oil Sands: Life-Cycle Assessments of Greenhouse Gas Emissions: