Multi-Objective Optimization of Environmental Impacts of Bio- Based Industry Production Processes: A Case Study

This work presents a Multi-Objective Optimization (MOO) framework that is applied to a specific case study in a Spanish context of the woodworking sector: the hot-pressing process of Laminated Strand Lumber (LSL) boards, which is one of the production processes to be evaluated within the CALIMERO project. The main objective is to simultaneously improve the two of the three dimensions that make up sustainability: environment and economy, focusing on the reduction of both environmental and economic burdens simultaneously. The MOO algorithm, which is at the heart of the framework, is based on evolutionary algorithms that allow the exploration of trade-offs between conflicting objectives by generating a set of solutions known as the Pareto front.

With such a purpose, the study is focused on a life cycle purpose, conducting a Life Cycle Assessment (LCA), apart from a Life Cycle Costing (LCC). According to the LCA, up to 16 different environmental impact categories are considered which are encompassing within the Product Environmental Footprint (PEF) methodology (e.g., climate change, water use, etc.), following an attributional cradle-to-gate approach. According to the LCC, primary data from industrial stakeholders is gather for estimating the operational expenditures (OPEX) of the manufacturing process.

The associated emissions are taken into account by simulating the production process using dedicated software and by varying the operational parameters that influence the final result (i.e. the LSL boards). In this sense, the 16 PEF impact categories, together with OPEX, serve as targets for the MOO algorithm. Through iterative optimization, the MOO algorithm navigates the space of operational parameters to identify a finite set of solutions that minimize all objectives while maintaining balance. This ensures that improvements in one area do not come at the expense of compromising performance in another.

The case study presented demonstrates the applicability and effectiveness of the MOO framework in addressing complex sustainability challenges, such as finding a balance between environmental sustainability and economic feasibility of specific production processes. An example of a forest product is presented. However, through further iteration and refinement, this can be applied to several additional case studies.