Network-Based Life Cycle Optimization of the Net Atmospheric CO2-eq Ratio (NACR) of Fuels and Chemicals Production from Biomass

Abstract

A biofuels and bioproducts conversion network is optimized over unit cost and unit greenhouse gas emissions objectives. We use a multiobjective, functional unit approach based on the life cycle analysis methodology with simultaneous consideration of capital budget constraints. A novel functional unit of mass of input biogenic CO2-eq is proposed to capture common benefits of bioproducts and biofuels. A novel dimensionless net atmospheric carbon ratio (NACR) for bioconversion processes is defined that captures the life cycle carbon footprint of the process from feedstock cultivation to product end use. The model is formulated as a nonconvex multiobjective mixed integer nonlinear fractional programming problem. We address computational complexity by developing a novel global optimization algorithm that incorporates the parametric algorithm and successive piecewise linear approximations to estimate nonconvex terms, and we introduce nonlinear programming subproblems to ensure global convergence under capital c...