Transport optimization of an anaerobic digestion co-product in a closed-loop supply chain

This research explores the opportunities and challenges of integrated logistics, covering both the inbound (supply) and outbound (distribution) transportation to/from an anaerobic digestion plant involving several types of suppliers and customers in a region of Quebec (Canada). All participants supply organic residues (in liquid or solid form), and some are also customers who require to receive and use the co-product. The residues are transported to the plant by two types of truck (tanker and solid bulk) of different capacities, where they are transformed by anaerobic digestion. The resulting co-product, a digestate used as an organic fertilizer, must then be efficiently distributed to the customers. The main objective of this project is to size a fleet of trucks adapted to the needs and capacity of the plant under study and minimize transportation costs. After defining and modeling the problem by using mathematical optimization, several scenarios reflecting different transportation strategies (backhauling and heterogeneous truck fleet configuration) have been tested. This article presents and compares the results of the different scenarios, highlighting the economic benefits and suggesting future research avenues. The preliminary results show that substantial transportation cost savings can be obtained by using backhauling and a heterogeneous fleet, reaching up to 17% when both are combined while decreasing the traveled distance by up to 42%.