Abstract

Natural gas has replaced coal as the dominant fuel for U.S. electricity generation. However, U.S. states that regulate electric utilities have retired coal more slowly than others. We build a structural model of rate-of-return regulation during an energy transition where utilities face tradeoffs between lowering costs and maintaining coal capacity. We find that the current regulatory structure retires only 45% as much coal capacity as a cost minimizer. A regulated utility facing a carbon tax does not lower carbon emissions immediately but retires coal similarly to the social planner. Alternative regulations with faster transitions clash with affordability and reliability goals.