Well-to-wheel life cycle assessment of transportation fuels derived from different North American conventional crudes

A life cycle assessment (LCA) is an extremely useful tool to assess the greenhouse gas (GHG) emissions associated with all the stages of a crude oil's life from well-to-wheel (WTW). All of the WTW life cycle stages of crude oil consume energy and produce significant amounts of GHG emissions. The present study attempts to quantify the WTW life cycle GHG emissions for transportation fuels derived from five North American conventional crudes through the development of an LCA model called FUNNEL-GHG-CCO (FUNdamental Engineering PrinciplEs-based ModeL for Estimation of GreenHouse Gases in Conventional Crude Oils). This model estimates GHG emissions from all the life cycle stages from recovery of crude to the combustion of transportation fuels in vehicle engines. The contribution of recovery emissions in the total WTW GHG emissions ranges from 3.12% for Mars crude to 24.25% for California's Kern County heavy oil. The transportation of crude oil and refined fuel contributes only 0.44–1.73% of the total WTW life cycle GHG emissions, depending on the transportation methods and total distance transported. The GHG emissions for refining were calculated from the amount of energy use in the refining of crude oil to produce transportation fuels. All the upstream GHG emissions were allocated to gasoline, diesel, and jet fuel. Refining GHG emissions vary from 13.66–18.70 g-CO2eq/MJ-gasoline, 9.71–15.33 g-CO2eq/MJ-diesel, and 6.38–9.92 g-CO2eq/MJ-jet fuel derived from Alaska North Slope and California's Kern County heavy oil, respectively. The total WTW life cycle GHG emissions range from 97.55 g-CO2eq/MJ-gasoline derived from Mars crude to 127.74 g-CO2eq/MJ-gasoline derived from California's Kern County heavy oil.