Effects of state and federal policy on renewable electricity generation capacity in the United States
更新数据后发现，州级可再生能源组合标准（RPS）对装机容量的促进作用不稳健，而2009年联邦经济刺激法案有显著正面影响，表明联邦行动对减排至关重要。
Multiple studies have examined the impact of state-level renewable portfolio standards (RPS) on renewable electricity generating capacity. Two of the most widely cited of these papers (Yin and Powers, 2010; Shrimali et al., 2015) both conclude that as an RPS mandates higher shares of renewable generating capacity within a state, utilities respond by increasing the renewable electricity generating capacity. When we update the data for those models, we find that conclusion is not robust. We also modify those models and extend the datasets out to 2018, and in every model-permutation fail to corroborate the original conclusions. Finally, we examine the impact of the 2009 American Reinvestment and Recovery Act, and find it has had a significant, positive impact on renewable electricity generating capacity. We conclude that state-level RPS are not a sufficient substitute for federal action to reduce greenhouse gas emissions from the electricity sector. Federal leadership matters. This paper also demonstrates the importance of investigating the robustness of previous results to data refinements.