Revisiting renewable portfolio standard effectiveness: policy design and outcome specification matter

Renewable portfolio standards (RPS) differ widely across US states. Prior research findings on the effectiveness of these policies to stimulate renewable electricity deployment are equally wide ranging. This study investigates patterns of RPS policy design and analyzes the effects on policy outcomes measured at the level of utility compliance. Measuring organizational outcomes of RPS corrects for the first time the challenges of prior research focused on state-level renewable capacity or generation outcomes. The quantitative analysis also takes into account the complexity of RPS design, by making use of a state-by-state database of RPS design characteristics developed for this study. Patterns of RPS design across states are compared, including the compliance schedule, scope, eligibility of resources, quotas and subsidies, renewable energy credit provisions, as well as enforcement and penalties. Together, the map of state RPS design and the new approach to RPS outcome analysis illuminate the diversity of RPS policy practice across the United States. They suggest the need to both account for the variety of design characteristics and accurately specify the policy outcomes in evaluations of these policies.