Future Refinery GHG Emissions: Evaluation of Potential Mitigation Technologies and Responses to Changing Fuel Demand
AdvisorBergerson, Joule A.
Committee MemberMahinpey, Nader
Pereira Almao, Pedro R.
Johansen, Craig T.
McCaffrey, William C.
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AbstractNorth American refineries are under pressure to deliver GHG emissions reductions and concurrently respond to changes in the demand for the products that they sell. In this thesis, a framework is developed based on Life Cycle Assessment (LCA), and energy systems modelling to evaluate these challenges. A techno-economic and LCA evaluation of a set of mitigation technologies is conducted by further developing the Petroleum Refining Life Cycle Inventory Model (PRELIM). This analysis, compares the performance of different refinery mitigation technologies using a tool that facilitates more fair comparisons by making consistent boundaries and assumptions. Results indicate these technologies could offer 3-44% GHG emissions reduction in a typical U.S. refinery. A second analysis is conducted by incorporating public data and refinery optimization procedures into PRELIM to conduct a PADD level analysis of the GHG emissions from U.S. refineries. This analysis demonstrates how a more complete picture of the U.S. refining sector can be obtained by going beyond individual refineries. A third analysis investigates the GHG emissions implications of the declining Gasoline-to-Diesel ratio (G:D) in U.S. refineries driven by fuel economy standards, driver behavior and biofuel mandates. Results indicate that the impact of G:D changes on refining GHG emissions within existing operational flexibility of U.S. refineries is negligible on a country level (~3%) but variations within individual regions could be as high as 8%. Hydrogen typically produced via steam methane reforming constitutes up to 30% of refining GHG emissions necessitating the evaluation of alternative technologies to counteract this impact and reduce emissions further. A fourth analysis provides a techno-economic analysis and LCA of High Temperature Steam Electrolysis (HTSE) by integrating Aspen HYSYS® modelling into LCA. Results indicate GHG emissions of 3-20 kgCO2/kgH2 and cost of $2.5-5/kgH2 are possible depending on the system parameters (e.g., energy source, fuel cell lifespan). Consequently, a carbon price of $360/tonneCO2 that could decrease to $50/tonneCO2 with future technology advancements might be required to make HTSE competitive with SMR. The framework introduced in this thesis can guide analyses that can help inform decision-making related to investment decisions and GHG emissions policy where refineries are concerned.
Schulich School of Engineering