Two-objective modeling of Location-allocation problem in a green supply chain considering transportation systems and CO2 emission

In this paper, we study the facility location problem. A three-level supply chain model including plants, warehouses and retailers is presented. Different types of products are transported through different modes of transportation between manufacturing plants, warehouses and retailers. Customers' demand from retailers depends on the location of retailers and product types. Today, one of the most important challenges in organizations is controlling greenhouse gas emissions across the grid; however, given the complexity of green supply chain problems, providing a solvable model is important. In this study, in order to simplify the mathematical model, only the CO2 released in the supply chain network is considered. It is also assumed that each facility, according to demand, creates a certain amount of pollution, and the pollution created by the vehicles depends on the mileage. The proposed model aims to minimize the total network cost and CO2 emissions. The proposed solving method for solving the model is multi-choice goal programming method. In order to evaluate the efficiency of the proposed method, the results were compared with the results of the ε-constraint method and sensitivity analysis of the necessary parameters was also performed.