In the last several years, two mechanisms for increasing the supply of renewable electricity have become increasingly popular: renewable portfolio standards, a state policy of mandating increased production of green power; and green pricing programs, which allow customers to purchase green power through their utilities. These mechanisms have been effective in increasing the adoption of renewable energy; however, it is unclear whether they interact in a way that is mutually beneficial or counterproductive. It is important to understand the effect of renewable portfolio standards on the voluntary market for green energy, especially as Congress considers a nationwide portfolio standard. The effectiveness of a renewable portfolio standard may be undercut if it leads customers to purchase less green power.

This study analyzes the relationship between the passage and implementation of a renewable portfolio standard and two measures of enrollment in utility green pricing programs. Using eight years of data for all fifty states, the study utilizes multiple regression analysis with fixed-effects estimation. The results indicate that the passage of a renewable portfolio standard has a positive and statistically significant effect on green pricing enrollment within the state. At the same time, the rate at which states increase the stringency of the renewable portfolio standard is found to have no effect on enrollment. Although further study is needed to determine if additional factors are responsible for the observed increase in green pricing enrollment, this study provides evidence that such programs do not harm, and may in fact encourage, voluntary purchases of green power.