A study in the Journal of the Association of Environmental and Resource Economics entitled “External Impacts of Local Energy Policy: The Case of Renewable Portfolio Standards” finds that increasing the renewable portfolio standard (RPS) in one state reduces coal generation in neighboring states through trading of renewable energy credits (RECs). This contrasts with findings on greenhouse gas emission “leakage” under California’s cap and trade program put forth by the authors at the Energy Institute at Haas at the University of California here and here.

These latter set of findings has been used California Public Utilities Commissioners to argue against the use of RECs and implication that community choice aggregators (CCAs) are not moving forward increased renewables generation. This new study appears to land on the side of the CCAs which have argued that even relying on RECs in the short run have a positive effect reducing GHG emissions in the West.