Research on the Connection Market Trading Issues of Green Certificates and CCER Based on Contribution Degree and Social Welfare

The connection between the green certificate market and the CCER market can further achieve the dual carbon goals, so it is imperative for the green certificate market, CCER market, and the connection market to coexist. it is necessary to convert green certificates into CCER in the connection market to achieve transactions between the two. The research is aimed at exploring the interface between green certificates and CCER, with the main objective of finding trading mode and trading method to address the interface between the two. This paper firstly proposes a concept of contribution degree that assists fair trading in the market, based on the different ways in which contribution degree is introduced in the trading of green certificates, CCER markets, and connecting markets, and establishes basic trading mode, unilateral contribution trading mode (UCM) and bilateral contribution trading mode. Then, the rolling matching trading model with the goal of maximizing total social welfare, the contribution degree model and the effect test model are established to realize the implementation of the above three modes through different combinations of the models. Finally, the quantitative results are obtained by simulating the trading situation of the three modes, and CCER offset ratio and contribution degree indicator weight are discussed. The results show that it is feasible to build a bridging market between green certificate and CCER by using the contribution degree, in which the UCM is the optimal solution to achieve the dual-carbon goal and market development. The setting of CCER offset ratio can be based on the difference of enterprise types, and the weight of indicators affecting the contribution level should be adjusted with the policy. The research in this paper has the following contributions: (1) a new criterion to satisfy fair trade—contribution degree is proposed to provide ideas for mutual recognition of products in the bridging market, and proposed a contribution degree calculation model for the green certificate and CCER markets, as well as the bridging market; (2) from the perspective of the contradiction between supply and demand in the market and fair trade, different schemes to build a bridging market are given in a fixed context and compared and analyzed; (3) from the market level, the quantitative analysis of the indicator settings affecting emission reduction, providing suggestions for the differentiated evaluation of warrants and the formulation of carbon reduction policies.