Electricity pricing under “carbon emissions trading”: A dominant firm with competitive fringe model

The aim of this paper is to analyze the impact of trading of CO2 emissions allowances on electricity pricing in the short run. We mainly refer to the European Emissions Trading Scheme (ETS) and are interested in understanding the role of electricity market structures. We carry out a simple analytical model useful to verify whether (and under which conditions) the impact of the ETS under market power could be lower (or higher) than that under perfect competition. We analyze a context where generators compete in a uniform, first price auction. Market power in the form of a dominant firm facing a competitive fringe model is assumed. The paper highlights that the marginal CO2 opportunity costs are fully included in energy prices when the electricity market is perfectly competitive. Under market power the impact of the ETS equals or exceeds that under the competitive scenario only when there is excess capacity and the share of most polluting plants in the market is low enough. Otherwise, the impact under market power is less than under perfect competition and significantly decreases in the degree of market concentration. This especially occurs when there is not high excess capacity and regardless of either the plant mix or the allowance price. In this case, moreover, the marginal pass-through rate is lower in the peak than in the off-peak hours and can be even nil if the degree of market concentration is high enough.