Regulating a Polluting Oligopoly: Emission Tax or Voluntary Agreement?

This paper compares, in a polluting oligopoly, an emission tax and a form of environmental policy called voluntary agreement (VA). Here there are two ways of reducing pollution: output contraction and end‐of‐pipe abatement. Given the imperfect competition, firms’ reaction to the tax is sub‐optimal. They reduce output excessively in order to raise the price and do not abate enough. The VA is a take‐it‐or‐leave‐it contract on abatement effort, offered to the firms with the threat of a tax. It has a limited effect on output and always allows higher abatement than the tax. We find that this kind of VA may be more efficient than the tax in a concentrated industry, when pollution is not too harmful and when the abatement technology is rather efficient and cheap.