Imperfect competition, emissions tax and the Porter hypothesis

This paper investigates the conditions under which the design of an emissions tax can align social and private interests. Our contribution is to determine the general conditions for firms' profits and social welfare to be higher under the implementation of an emissions tax than under no tax. We consider n firms producing an homogeneous product and competing over supply schedules, which covers a continuum of imperfect competition equilibria from Bertrand to Cournot. We show that, as competition intensifies, the pass-through of the tax to consumers increases, to a point where the price rises more than offsets the net result of the investment outlay. Our analysis provides new insights into the trade-off between environmental policy, market competition and the so-called "win-win" outcome for firms and society.