The Waste-to-Biomethane Logistic Problem: A Mathematical Optimization Approach.

Area of Science:

• Operations Research
• Environmental Engineering
• Biotechnology

Background:

• Designing complex logistic systems for waste-to-biogas production is challenging.
• Existing methods may lack flexibility in optimizing plant placement and product distribution.

Purpose of the Study:

• To develop a novel mathematical optimization approach for the optimal design of waste-to-biogas logistic systems.
• To create a flexible decision-aid tool for locating pretreatment, anaerobic digestion, and biomethane liquefaction plants and pipelines.
• To optimize the distribution of products from waste to biomethane within the supply chain.

Main Methods:

• Formulation of a mathematical optimization model.
• Analysis and reduction of model variables and constraints.
• Solving real-size instances using computational experiments.

Main Results:

• The proposed model efficiently solves large-scale synthetic instances (up to 500 farms) within reasonable CPU times (<2 hours).
• A real-world case study demonstrated the model's validity, with solutions obtained between 2 minutes and 6 hours.
• Solution times are influenced by budget constraints and biomethane injection requirements.

Conclusions:

• The developed mathematical optimization approach provides a valid and versatile tool for designing waste-to-biogas logistic systems.
• The methodology is adaptable to various waste transformation scenarios.
• The tool enables optimal decision-making for plant location and product distribution, facilitating efficient biogas production.