In this study, the U.S. Department of Energy (DOE, the Department) seeks to provide information about transmission congestion by focusing on specific indications of transmission constraints and congestion and their consequences. The study focuses primarily on a specific time frame: historical trends over the past few years, and looking into the future to the extent available studies permit. It does not apply congestion labels to broad geographic areas such as the “critical congestion areas,” “congestion areas of concern,” and “conditional congestion areas” identified in earlier studies. For analytic convenience, the study’s results are presented and discussed in relation to four large regions of the United States: the West, Midwest, Northeast, and Southeast. The area covered by the Electric Reliability Council of Texas (ERCOT) is excluded by law from this study.
This study identifies (to the extent supported by publicly available data as of 2012, with limited updates in December 2013) where transmission constraints and congestion occur across the eastern and western portions of the U.S. electric power system. All of the conclusions presented in this study are based on (and limited to) the data reviewed, which are all publicly available data series, studies, analyses, and reports. The Department reviewed more than 450 sources in preparing this report, all of which are listed by name in Appendix E. DOE did not conduct independent modeling for this study. The Department of Energy does not endorse and has not independently validated the data and information compiled and reported in this study.
The transmission constraints and congestion identified in this study represent a snapshot in time. The study focuses on transmission constraints and congestion in the recent past as well as current expectations for the future to the extent available studies permit. Congress directed the Department to conduct a congestion study every three years. The Department plans to initiate a fresh study of transmission constraints and congestion impacts in 2015. In addition to the triennial congestion studies, the Department will work with the Energy Information Administration (EIA) and the Federal Energy Regulatory Commission (FERC) to prepare an annual Transmission Data Review summarizing publicly available data and information on transmission matters, including congestion.