Integrating Hybrid Life Cycle Assessment with Multiobjective Optimization: A Modeling Framework

By combining life
cycle assessment (LCA) with multiobjective optimization
(MOO), the life cycle optimization (LCO) framework holds the promise
not only to evaluate the environmental impacts for a given product
but also to compare different alternatives and identify both ecologically
and economically better decisions. Despite the recent methodological
developments in LCA, most LCO applications are developed upon process-based
LCA, which results in system boundary truncation and underestimation
of the true impact. In this study, we propose a comprehensive LCO
framework that seamlessly integrates MOO with integrated hybrid LCA.
It quantifies both direct and indirect environmental impacts and incorporates
them into the decision making process in addition to the more traditional
economic criteria. The proposed LCO framework is demonstrated through
an application on sustainable design of a potential bioethanol supply
chain in the UK. Results indicate that the proposed hybrid LCO framework
identifies a considerable amount of indirect greenhouse gas emissions
(up to 58.4%) that are essentially ignored in process-based LCO. Among
the biomass feedstock options considered, using woody biomass for
bioethanol production would be the most preferable choice from a climate
perspective, while the mixed use of wheat and wheat straw as feedstocks
would be the most cost-effective one.