Modeling of a logistics network for wood flows from by-products and cascade utilization

Waste Wood and wood by-products have the potential to become attractive alternative sources of raw materials. Their efficient use is important due to the rising demand and limited supply of forest wood. Cascade utilization is gaining interest as a strategy to bridge the gap between rising wood demand and fresh wood availability. However, the economic and environmental impacts of a cascading system for wood-based products are not fully known. In this work, an investigation is conducted to determine the consequences of cascade utilization for the economic and environmental performance of logistics networks for wood flows. Two case studies in Lower Saxony consider five wood products, including medium density fiber (MDF), oriented strand board (OSB), particleboard, coated paper, and wood pellets. In the first case study, an approach for decision support is developed that consists of a mixed-integer linear programming (MILP) model. In the first case study, the MILP model is used for minimizing the costs of the logistics network for three scenarios. Then the UMBERTO software is applied to determine the quantity of CO2e of the minimized logistics network. In the second case study, the MILP model is enhanced using two objective functions, as cost and global warming potential (GWP) are considered simultaneously. In this case study, it is observed that environmental parameters such as CO2 emissions can also be implemented in the MILP. The utilization of a multi-objective optimization model brings new perspectives (the trade-off between two contradictory objective functions, for instance) in comparison to the first case study, in which CO2 is calculated as an off-line step after logistics costs are minimized.