A framework of carbon-neutral waste transportation: Modeling and sensitive analysis

This study is aimed at helping third-party logistics companies to achieve carbon neutrality, which is a challenge they will face in the near future. From the perspective of carbon neutrality, this paper studies two types of vehicle routing problems (VRP) regarding third-party logistics: One is the carbon-neutral vehicle routing problem (CNVRP), and the other is the multi-stage carbon-neutral vehicle routing problem (MSCNVRP). In this paper, we consider three objective functions for the CNVRP and MSCNVRP models respectively: total cost minimization, fleet size minimization, and carbon emission minimization. We first linearize the constructed nonlinear CNVRP and MSCNVRP models, and then verify the validity and reliability of the models through numerical examples. Numerical experimental results show that considering the total cost minimization objective leads to a better solution for fleet size and routing in transportation. In addition, in terms of the uncertainty of carbon sink price, the MSCNVRP model has more advantages than the CNVRP model. Changes in carbon sink prices and the availability of funds to achieve carbon neutrality have no effect on fleet size and vehicle routing for models whose objective functions are to minimize total costs, but models with the objective functions of minimizing fleet size or carbon emissions are more sensitive. The results also showed that companies with multiple types of vehicles have an advantage in transportation costs. In particular, the models proposed herein can provide flexible solutions for companies in third-party logistics to achieve carbon-neutral transportation.