Abstract
Refineries are major sources of direct CO2 emissions, primarily from steam generation, fluid catalytic cracking, and hydrogen production. This study develops a superstructure optimization framework to evaluate the economic and environmental viability of retrofitting existing refineries with small modular nuclear reactors (SMRs) for cogeneration of heat and electricity. A multi-period mixed-integer quadratically constrained program is formulated, simultaneously minimizing the present cost of retrofitting and CO2 emissions over the time horizon. This problem is solved to generate a Pareto frontier via the e-constraint method. Two cases are analyzed for a medium-scale refinery, considering 1) inflexible operation under average annual electricity prices and 2) flexible operation under hourly prices with the possibility of installation of storage devices. Compared to a benchmark without SMRs in the superstructure, allowing their installation leads to reduced costs at lower or comparable emission levels. The results show that SMRs are primarily used for high-pressure steam generation. Flexible operation and the inclusion of thermal energy storage further reduce costs. Overall, SMRs appear in multiple non-dominated solutions, highlighting their potential as a cost-effective refinery decarbonization strategy.