Effluent taxes, market structure, and the rate and direction of endogenous technological change

This paper studies the effects of effluent taxes on firms' allocation of resources to cost-reducing and emission-reducing R&D, and on entrepreneurs' decisions to develop new goods and enter the market. A tax set at an exogenous rate that does not depend on the state of technology reduces growth, the level of consumption of each good, and raises the number of firms. The induced increase in the variety of goods is a benefit not considered in previous analyses. In terms of environmental benefits, the tax induces a positive rate of pollution abatement that offsets the "dirty" side of economic growth. A tax set at an endogenous rate that holds constant the tax burden per unit of output, in contrast, has ambiguous effects on growth, the scale of activity of each firm and the number of firms. Besides being novel, the potential positive growth effect of this type of effluent tax is precisely what makes this instrument effective for welfare-maximizing purposes. The socially optimal policy, in fact, requires the tax burden per unit of output to equal the marginal rate of substitution between the growth rate of consumption and abatement. Moreover, a tax/subsidy on entry is needed, depending on whether the contribution of product variety to pollution dominates consumers' love of variety.