Optimal policy for environmental goods trade in asymmetric oligopolistic eco-industries

In this paper, we examine the optimal structure of an environmental tax to pollution, a production subsidy to a domestic eco-industry, and an import tariff on environmental goods (EGs) in a two-country model where the home country imports EGs from the foreign country. Home and foreign firms that produce EGs engage in Cournot competition. We then assume that the number of the home local firms which produce EGs is constant, but that of the foreign firms is variable. Our main findings are as follows: (I) The optimal environmental tax level may be lower than the Pigouvian level even if the tax has a positive impact on the output of EGs produced by a domestic firm. (II) The optimal tariff level may be positive when the country implements the first best policy combination in a closed economy regarding the environmental tax and the subsidy. (III) The optimal subsidy level may be positive, and then the subsidy may be substitutive for the import tariff on EGs.