关键词: 污染容量, 排放标准, 排污税, 排污权交易, 混合政策, 微分博弈

Abstract: Environmental pollution originates from the excessive discharge of pollutants by industrial firms. However, due to the pollutant attributes of externality and public goods, firms are reluctant to reduce their emissions or invest in emission abatement activities, resulting in market failure. Therefore, governments have adopted command-and-control or market-based environmental policies, such as emission standards, taxes, permit trading, etc., to govern the environment. China’s current environmental pollution management policies for enterprises are based on command-and-control pollution emission standards and pilot emissions trading systems in some domestic cities. At the same time, the official implementation of the Environmental Protection Tax Law of the People’s Republic of China in 2018 marked a shift from administrative command-based to various policies combining administrative and market-based policies. For this reason, how the government selects a reasonable environmental policy for the specific situation in its region is an urgent problem to be solved. In this context, this paper takes the government as the core perspective and selects four scenarios of emission standards, emission taxes, emissions trading, and mixed policies of emission reduction subsidies, and establishes a Stackelberg differential game model between the government and enterprises in which the enterprises take profit maximization as the decision objective. The government takes social welfare maximization as the decision objective under the dynamic change of regional environmental pollution capacity. The Nash equilibrium solutions are compared and analyzed, and finally, numerical analysis is performed, and relevant management strategies are given according to the results.
The results of the study find that: If the cost of emission reduction is the same among enterprises, emission standards, and emission taxes, and emissions trading are equivalent, the environmental benefits are better than those of the mixed policy, and social welfare under the mixed policy is better than other policies only when the harm to the environment is less than a certain value; When the cost of emission reduction is different among enterprises, emission taxes, and emissions trading are equally equivalent, the environmental benefits under emission standards are lower than those of emission taxes and emissions trading, and the environmental benefits under the mixed policy. The environmental benefits are the lowest under the mixed policy. Finally, the dynamic trajectory analysis of pollution capacity and social welfare is analyzed by numerical simulation, which provides a scientific basis for the government to effectively control pollution.
This study helps to improve the government’s environmental policy analysis and optimal decision-making in dynamic situations and has some reference value for regional pollution management. However, there are some improvements. For example, this paper only considers the environmental policy regulation of government enterprises in a region. More and more regions are affected by the pollution emissions of enterprises in neighboring regions, such as the Beijing-Tianjin-Hebei region in China. In this case, the government’s environmental policy regulation should consider the harm caused by the pollution of enterprises in the region and the influence of environmental policies of enterprises and governments in the surrounding areas on their decisions. In addition, many scholars believe that the relationship between government and enterprises is not only between regulating and being regulated but also between collusion and possible collusion, at which point the analysis of environmental policy and collusion between the two parties as well as central government regulation, is the focus of future research.

Key words: pollution stock, emission standard, emission taxes, emission permits trading, mixed policy, differential game