Regional upstream life-cycle impacts of petroleum products in the United States

Abstract

The upstream environmental impacts of petroleum-derived materials are vital to the life-cycle assessment of many complex systems because petroleum products are used in countless applications as fuels or raw inputs. Currently, there exists no transparent data source for these upstream impacts that account for critical regional differences in crude oil sources and refinery fuels within the United States. This study describes the framework for a streamline life-cycle inventory (LCI) model that can be used to calculate the upstream environmental impacts of major petroleum products in five U.S. regions. The system boundaries considered in the model include crude oil extraction and flaring, crude oil transportation, oil refining, refined oil transportation, and product storage. High-level activity data for production stages are compiled along with supplementary inventory data that can be used to develop an LCI model. Two case studies demonstrate applications of the LCI model and the effect of methodological choices in the model. A case study investigating regional effects on asphalt binder production, as a road paving material, found a 15% average difference in the overall energy consumption and global warming potential (GWP) from producing asphalt mixtures due to geographical variation. A second case study considering the effects of varying refinery allocation on the production of diesel fuel used by the U.S. trucking industry found a difference of up to 0.3 billion tons of CO2eq of GWP (2.1%) and 4.7 trillion MJ of energy (2.5%) over a projected 36 years due to allocation choice. The LCI model outlined in this study can be readily implemented in larger product systems, with the ability to capture critical regional and methodological differences in material production.