(455f) Life Cycle Assessment and Multiobjective Optimization in a Natural Gas Based Petrochemical Complex

In this work, we address the optimization of a natural gas based petrochemical complex using economic and environmental criteria. The mathematical model includes linear and non-linear models for single plants, taking into account main operating variables, intermittent deliveries and inventory variable profiles. The environmental objective is measured with the global warming potential (GWP) and ReCiPe metrics according to the life cycle assessment procedures using indicators at two levels: eighteen midpoint indicators and three endpoint indicators realised in SimaPro (Pre-Consultants, 2015).The resulting mixed integer nonlinear programming (MINLP) models are implemented in GAMS. The bi-criteria MINLP model is solved with the ε-constraint method. Mid-point indicators are presented for current conditions. Numerical results show that the petrochemical complex can satisfy product demands while improving the environmental performance by decreasing greenhouse gases emissions in 33 %, from 1,042 to 695.33 kt CO₂-eq/year in the case of GWP minimization.