Thermodynamic and Thermoeconomic Assessment of a Sugarcane–Corn Flex Biorefinery

Flexible sugarcane–corn biorefineries have emerged as a promising strategy to enhance biomass conversion efficiency and ensure year-round operation in Brazil’s bioenergy sector. However, the thermoeconomic behavior of such systems remains insufficiently explored. This study presents a comprehensive exergoeconomic assessment of a sugarcane–corn flex biorefinery operating under three scenarios: (1) seasonal sugarcane-only production, (2) off-season corn ethanol production using stored bagasse, and (3) fully integrated year-round operation. The methodology combines mass, energy, and exergy balances with exergy-based cost accounting to quantify the monetary impact of exergy destruction and identify the main thermoeconomic cost drivers. Results demonstrate that full integration significantly enhances system performance, increasing overall annual efficiency from 25.27% to 61.26% through improved steam management, reduced irreversibilities, and minimized unused thermal resources. These improvements are directly reflected in economic performance, with the production costs of sugarcane ethanol and surplus electricity estimated at 1.42 BRL L⁻¹ and 60.31 BRL MWh⁻¹, respectively. Sensitivity analysis further indicates that the integrated configuration maintains superior economic performance across a wide range of feedstock prices and electricity market conditions, demonstrating its operational robustness. Overall, this study advances the understanding of thermoeconomic behavior in flexible biorefineries by explicitly linking exergy destruction to cost formation and provides a consistent framework to support decision-making toward more efficient and economically resilient bioenergy systems.