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Interconnections Seam Study

Through the Interconnections Seam Study, NREL joins national lab, university, and industry partners to identify cost-effective options for upgrading the U.S. electric grid to create a more integrated power system that can drive economic growth and increase efficient development and utilization of the nation's abundant energy resources, including solar, wind, and natural gas.

NREL conducted the initial scenario analysis for the Interconnections Seam Study and is now conducting further analysis and model enhancements as requested by the U.S. Department of Energy. That process is currently underway. The full study will be released once completed. For media inquiries, please contact David Glickson.

Map of the continental United States that reflects major power system regions and the strong solar resource across the South and Southwest and strong wind resources primarily in Texas and the Great Plains states.

Stitching together the major regions of the U.S. power system, represented here conceptually, could enhance the ability to harness abundant renewable resources and balance loads across the country.

Strengthening the U.S. Power System

The three major components of the U.S. power system—the Western Interconnection, the Eastern Interconnection, and the Electric Reliability Council of Texas—operate almost independently of each other. Very little electricity is transferred between the interconnections.

This study aims to quantify the value of strengthening the connections (or seams) between the regions to encourage efficient development and utilization of U.S. energy resources. The study also assesses the degree to which interconnection can facilitate a more reliable, resilient, sustainable, and affordable U.S. electricity system.

Modeling Approach and Preliminary Results

To quantify the value of enhancing the U.S. interconnection seams, the study team is analyzing a suite of power system futures. The study utilizes and analyzes results from three classes of power system models: long-term capacity expansion, year-long production cost, and AC power flow. The end result: in-depth insight on the economic, environmental, reliability, and resiliency benefits of the study scenarios.

Research Team


Pacific Northwest National Laboratory

Argonne National Laboratory

Oak Ridge National Laboratory

Iowa State University

Southwest Power Pool

Midcontinent Independent System Operator

Western Area Power Administration

Technical Review Committee

Representatives from more than 30 utilities, power system operators, and industry organizations are helping guide this study by helping to define the study questions and methods and reviewing findings. We welcome input and involvement from all power system stakeholders. The following entities have participated in our TRC meetings:

  • Alberta Independent System Operator
  • Basin Electric Power Company
  • Black Hills Energy
  • Energy Exemplar
  • El Paso Electric
  • Electric Power Research Institute
  • Electric Reliability Council of Texas
  • Great River Energy
  • Hydro Quebec
  • Independent System Operator of Ontario
  • LS Power
  • Manitoba Hydro
  • Minnesota Power
  • National Grid
  • National Rural Electric Cooperative Association
  • NB Power
  • NextEra
  • NS Power
  • Public Service Company of New Mexico
  • SaskPower
  • SDG&E
  • Solar Energy Industry Association
  • Transcanyon
  • Tri-State Generation and Transmission
  • Utility Variable Generation Integration Group
  • Western Electricity Coordinating Council
  • Xcel Energy
Graphic of a map of wind power resource in the United States, depicting average wind speeds at a 100-meter hub height for the year 2012 derived from modeled resource estimates.

Map of United States Wind Power Resource

Graphic of a map of solar resource availability in the United States, depicting annual average daily total solar resource using 2012 data, reflecting high concentrations of solar in the South and Southwest regions.

Map of Global Horizontal Solar Irradiance

Graphic of a map of the U.S. Transmission system, showing transmission lines across the United States and seven points of high-voltage direct-current power transmission ties in Miles City, MT; Rapid City, SD; Stegall, NE; Sidney, NE; Lamar, CO; Clovis, NM; and  Artesia, NM.

Map of U.S. Transmission System and B2B HVDC Ties


Joshua Novacheck