Environmental Regulation, Market Power, and Socially Responsible Firms

We study environmental policy in imperfectly competitive markets where firms differ in their objectives. Alongside standard profit-maximizing firms, we consider welfareoriented firms that partially or fully internalize environmental externalities but are subject to financial viability constraints. Wedevelop a Cournot model in which production generates emissions and firms may differ in the extent to which they account for environmental damages. We characterize market equilibria and examine the effects of environmental taxes and output subsidies on emissions, output, profits, and welfare. Our analysis shows that standard Pigouvian prescriptions are modified by the presence of market power and by the break-even constraints faced by welfare-oriented firms. While emissions taxes reduce environmental damages, they may also exacerbate underproduction and threaten the viability of socially responsible firms. Conversely, output subsidies may improve welfare despite increasing emissions. The welfare ranking of policy instruments depends critically on the interaction between environmental externalities, imperfect competition, and firms' financial constraints. These findings suggest that environmental policy design should account not only for emissions reduction, but also for the market structure and sustainability of firms with socially oriented objectives.