The impact of carbon policies on supply chain network equilibrium: carbon trading price, carbon tax and low-carbon product subsidy perspectives

This study takes a supply chain network composed of manufacturers, retailers and demand markets as the research object and analyses the impact of the government's carbon trading price (CTP), carbon tax (CT) and low-carbon product subsidy (LPS) policies on the supply chain network equilibrium. We determine the equilibrium state of members by using variational inequality and then construct a network equilibrium model that considers these three policies. A modified projection algorithm is used to verify and solve the model. The results show that a higher CTP helps to reduce carbon emissions but reduces the transaction quantity of products. Further, when the CTP increases, the system's profits increase only under the LPS policy. However, regardless of the CTP level implemented, if the CT rate is higher than the subsidy level, carbon emissions are lower. Notably, under the same levels of LPS and CT, LPS has a greater effect on the system.