Optimization of Collection and Transportation Logistics Chains for Low-Grade Wood and Sawmill Residues for Bioenergy Plants in the Arkhangelsk Region: Modeling Based on Mixed Integer Linear Optimization

The article addresses the problem of high logistics costs when utilizing forest residues for bioenergy in the Arkhangelsk region, where approximately 5001200 thousand tons of sawmill residues are generated annually, but their utilization is limited due to source remoteness, weak infrastructure, and seasonal factors. The study's objective is to minimize total logistics costs, including transportation, storage, and operational expenses, while ensuring the loading of bioenergy capacities. Methods include mixed integer linear programming (MILP), simulation of three scenarios (baseline, winter, spring), and geospatial analysis to calculate distances and flows. Results indicate an optimal structure: opening 3–4 collection points (in Arkhangelsk, Kotlas, Onega, and additionally in southern areas), preference for multimodal transport (water and rail), volume distribution with predominance of water transport in spring (up to 60 thousand tons on specific routes). Cost reductions reach 18–32% compared to the current scheme (only road transport to nearest points). The scientific novelty lies in integrating seasonality (passability coefficients 0.4–1.2), variability in residue formation (winter +20%, summer –20%), transport multimodality (road, rail, water) and regional infrastructure constraints (Northern Dvina River, railways 1767 km long), enabling model adaptation to northern conditions. Results can support regional bioenergy development programs, enhancing sustainability and reducing emissions.