A Multi Objective Model for Optimization of a Green Supply Chain Network
Because of leading the environmental disasters, the global climate alteration has been one of the most important controversial issues in decades. The greenhouse gas emissions (CO2, methane, nitric oxide, ozone etc.) begin with the industrial revolution. After this milestone, the global warming is getting worst as long as the energy demands are met by the fossil fuels. There are a lot of factors to evaluate the performance of the supply chains such as customer service, quality, lead time, cost etc. But due to the environmental requirements (social responsibilities, Kyoto Protocol, government agencies etc.) an increasing attention has to be given to develop environmental strategies. If the aforementioned environmental applications are considered in the supply chains, then we called Green Supply Chain (GrSC). This study develops a model of a closed-loop supply chain network which starts with the suppliers and recycles with the decomposition centers. As a traditional network design, we consider minimizing the all transportation costs and the raw material purchasing costs. To pay attention for the green impacts, different transportation choices are presented between echelons according to their CO2 emissions. The plants can purchase different raw materials in respect of their recyclable ratios. The focuses of this paper are conducting the minimizing total CO2 emissions. Also we try to encourage the customers to use recyclable materials as an environmental performance viewpoint besides minimizing total costs. A multi objective linear programming model is developed via presenting a numerical example. We close the paper with recommendations for future researches.