Market Power and Welfare in Electricity Markets Employing Tradable Green Certificate Systems

Within the last 25 years, liberalization (deregulation) of electricity markets around the world has been undertaken with the goal of replacing long-standing monopoly rights with fully competitive markets. In addition, many nations have begun employing "tradable green certificate" systems to promote electricity generation from renewable ("green") energy sources (wind, solar, biomass, hydroelectric, etc.), with the primary objective of mitigation of greenhouse gas emissions from fossil fuel ("black") producers. In this paper, we examine some welfare implications of the use of green certificate systems in electricity markets under alternative market structures. We demonstrate that under a wide variety of scenarios, an oligopolistic market structure may perform better in terms of welfare than a competitive market structure. We also demonstrate that there will typically be an optimal level of market power summarized by a conjectural variations parameter that depends on the cost structure of both green and black firms. Our model provides insights into the policy challenge of electricity market design and suggests an approach that could be applied in a more general model.