低碳环境下供应链纵向减排合作的动态协调策略

Dynamic Coordination Strategy of Vertical Cooperative on Carbon Emission Reduction in Supply Chain under Low-carbon Era

低碳环境下,考虑供应链上下游企业减排合作效果的跨期性和低碳产品需求的特征,借助微分博弈研究了单个供应商和单个制造商长期合作的两级供应链中合作减排问题。假设需求是产品减排量的线性函数,分别分析了供应链减排中制造商占主导供应商跟随的Stackelberg博弈情形及制造商与供应商纵向合作减排的情形,构建了两种情形下的动态模型,得到了各自相应的反馈均衡策略及产品碳排放量随时间变化的最优轨迹;并比较这两种反馈均衡策略,发现合作减排策略能提高产品的减排量,供应商和制造商以及整个供应链系统的利润也比非合作减排时有所提高,实现了供应链企业间的协调;最后,通过数值分析,验证了结论的有效性,并对相关参数进行了灵敏度分析,为供应链企业间的合作减排提供理论依据。

Research has already shown that global warming has a direct relationship with the emission of carbon and other greenhouse gases. Actions on climate change have been topping priority lists in many countries, especially with increasing pressures from the public. Many countries have attempted to enact legislation or design market-based carbon trading mechanisms for controlling carbon emission. Twelve countries and regions have enacted legislation to require that enterprises carry out carbon labeling systems. More than 1000 famous enterprises require ＂low carbon＂ in their supply chains, such as Wal-Mart, 1BM, IKEA, which have asked their suppliers to provide carbon labels. On March 2013, The National Development and Reform Commission in China issued provisional rules on the management of low carbon products certification in order to identify the main content of China＇s low-carbon products certification system. Low-carbon products certification can boost the consumption side to promote energy saving and emission reduction. With low carbon products certification, consumers will be able to purchase products labeled low carbon based on their preferences in order to encourage companies to spend efforts in developing low carbon products. Low-carbon products certification systems have a big impact for upstream and downstream activities in many industries. Firms have focused for the most part on reducing emissions because of physical processes, business practices and operational policies. Thus, it has important practical significance to discuss about emissions reduction through the cooperation between enterprises in upstream and downstream supply chains from the perspective of management. This study considers that reduction rate can affect the cooperation of carbon emission reduction between enterprises in product demand, and the upstream and downstream supply chains. In addition, this study assumes that demand has a linear relationship with carbon emissions. Vertical cooperation on carbon emission reduction is discussed based on a differential game in a two-stage supply chain consisting of a single supplier and a single manufacturer. In the first part, we analyzed the Stackelberg game scenario in which manufacturer is a leader and supplier is a follower in the supply chain with the goal of reducing carbon emissions. In addition, we built the Stackelberg differential game models and solved this differential game by using the HJB equation to obtain feedback equilibrium strategy, the optimal function of profit about manufacturer and supplier, and an optimal trajectory for carbon emissions of product. In the second part, we analyzed the other scenarios in which vertical cooperation between manufacturers and suppliers about emission reduction was presented. Moreover, we attained a feedback equilibrium strategy of manufacturer and supplier and the optimal function of profit about the entire supply chain and optimal trajectory for carbon emissions of product. After comparing the two feedback equilibrium strategies, this study proposed that vertical cooperation strategies about emission reduction could improve the emissions of product, and the profit of supplier and manufacturer. The entire supply chain system is higher than non-cooperation supply chains because of the coordination among enterprises in the supply chain. At last, numerical analysis is conducted to verify the validity of conclusions. In addition, sensitivity analysis of the relevant parameters is conducted to understand the cooperation between enterprises in the supply chain.