Is it Worth it? A Comparative Analysis of Cost-Benefit Projectionsfor State Renewables Portfolio Standards

State renewables portfolio standards (RPS) have emerged as one of the most important policy drivers of renewable energy capacity expansion in the U.S. Collectively, these policies now apply to almost 40% of U.S. electricity load, and may have substantial impacts on electricity markets, ratepayers, and local economies. As RPS policies have been proposed or adopted in an increasing number of states, a growing number of studies have attempted to quantify the potential impacts of these policies, focusing primarily on projecting cost impacts, but sometimes also estimating macroeconomic and environmental effects. This report synthesizes and analyzes the results and methodologies of twenty-six distinct state or utility-level RPS cost impact analyses completed since 1998 (see Figure 1 and Appendix for a complete list of the studies). Together, these studies model proposed or adopted RPS policies in seventeen different states. We highlight the key findings of these studies on the costs and benefits of RPS policies, examine the sensitivity of projected costs to model assumptions, assess the attributes of different modeling approaches, and suggest possible areas of improvement for future RPS analysis.