Contextualizing Electric Transmission Permitting: Data from 2010 to 2020

A patchwork of entities plan, develop, and oversee the construction of electric transmission infrastructure across the U.S. The lack of centralized data, access restrictions, and the heterogeneity of the data units (e.g., miles, circuit-miles, megawattmiles) inhibits policymakers’ ability to fully understand and characterize the landscape of the U.S. transmission system. Likewise, there is not a comprehensive source for federal permitting data. Scarcity of accessible data means policymakers and advocates must often rely on anecdotal examples of electric transmission permitting as evidence. The report summarizes trends in transmission development, comparing projects that underwent an EIS to all transmission projects in the bulk power system. This analysis uses two distinct datasets and focuses on the period from 2010 to 2020. The first dataset includes 947 new transmission lines added to the bulk power system in the U.S. that came into service between 2010 and 2020 (referred to as the “New Lines dataset”). The second dataset includes an inventory of 37 electric transmission lines in the bulk power system that were in an active federal EIS process between 2010 and 2020 (referred to as the “EIS Lines dataset”). Finally, we contextualize our findings with planned and projected future transmission needs. The findings underscore the need for a comprehensive review of current permitting processes to promote the development of electric transmission infrastructure, crucial for delivering reliable, affordable, and low-carbon electricity