Integrated Assessment Of Economic And Environmental Performance Of Chemical Supply Chain Network Under Operational Uncertainty

Traditionally,process systems engineering(PSE)has focused on the design of chemical processes and has been focused on the plant level.However,there have been many important tasks in the past decade to expand the scope of its research to gain broader business experience.Chemical supply chain design is the product of this trend.Due to this trend,the supply chain management(SCM)field has recently become a key issue in the chemical process industry and is expected to gain more attention in the global market in the future because of fierce competition.It will force the company to operate under tighter profit margins.And as the government,enterprises and individuals continue to enhance their sense of sustainability,blind pursuit of economic benefits obviously can not meet the demand of the times.Therefore,it is necessary to consider the optimization of supply chain from the aspects of improving economic profit and reducing environmental impact.However,since economic goal and environmental goal are usually contradictory in actual optimization,the improvement of economic performance may lead to the reduction of environmental performance.At the same time,operational uncertainty affects both economic goal and environmental goal.And ignoring them will lead to decisions that do not reflect the actual situation or even get the opposite decisions.Operational uncertainty has the characteristics of repeatability and short period.Decision makers tend to make conservative decisions at this level.Therefore,this paper studied integrated assessement of economic and envirmental performance under operational uncertainty.And the chemical supply chain is the main research object,and life cycle assessment and multi-objective robust optimization is the entry point.Life cycle assessment is a tool for systematically quantifying product-related environmental factors and potential impacts.It is generally including two modeling method,namely process-based life cycle assessment(PLCA)and economic input-output based life cycle assessment(EIO-LCA).Since the research object of this paper is chemical supply chain,the products involved can generally be found in the product department of EIO-LCA.Therefore,the EIO-LCA is selected in this paper.And because the traditional LCA lacks a systematic way of generating such alternatives and identifying the best one in terms of environmental performance.Given the operational uncertainty in the actual operation of the supply chain,it has an impact on both economic and environmental objective functions.We combines the life cycle assessment(LCA)with the multi-objective robust optimization to establish a life-cycle robust optimization framework under it.Online EIO-LCA assessment tool developed by Carnegie Mellon University is been used in inventory analysis.EDIP is used to calculate environmental impact,and Analytic Hierarchy Process(AHP)is been used to integrated the multi-attributes of envirmental impact.The framework follows the three phases of classic Life Cycle Assessment(LCA).In the final phase,a series of economic and environmental trade-offs are automatically generated by combining the results of the third phase as an input with a multi-objective robust optimization tool.In the following part,basic parameters,variables and constraints is been used to describe the general problems in supply chain.Noted that the operational uncertainty is specifically the demand uncertainty.Next,the life cycle robust optimization framework is combined with general problems in supply chain.This lead to economic and environmental bio-objective robust optimization model under uncertain demand.And the eps-constraint is been used to solve it.Finally,it is applied to a global petrochemical supply chain.The results obtained by solving in GAMS show that the environmental impact of petrochemical supply chain ranges from 2.37ⅹ10~7 to 3.33ⅹ10~7,corresponding to the E[NPV]ranging from5.09ⅹ10~7$to 1.76ⅹ10~8$.In order to determin the optimal decision point,we further studies the correlation between the expected value of EDIP and environmental goals,and obtained the optimal decision point is c.The solution corresponding to this point can ensure the environmental performance of the supply chain and obtain considerable benefits.The results show that when the NPV is maximum,the maximum demand is the largest,while the environmental impact is also large;when the environmental impact is the minimum,Then we compared it with the stochastic optimization model,the conclusion is that the environmentally-friendly decision-making area of the robust optimization model is smaller than the stochastic optimization model.And demand satisfaction in stochastic optimization model is close to the minimum demand when the environmental impact is minimized.In this situation,the model proposed in this paper compare with it,demand satisfaction increased by 26%.