Interconnections Seam Study

The National Renewable Energy Laboratory (NREL) conducted the Interconnections Seam Study to analyze the costs and benefits of optimized nationwide transmission expansion. The study develops four transmission designs with various levels of increased transmission capacity aimed at connecting the nation’s main grid regions. Each design scenario is analyzed under eight scenarios with different assumptions regarding transmission costs, renewable generation levels, wind and solar costs, gas prices, and generator retirements. Between 2024 and 2038, the analysis finds total transmission investment needed ranges from $40 billion under a base scenario to $101 billion under a high variable generation scenario where 39% of annual generation is composed of wind and solar. The study approximates cost-to-benefit ratios over a 35-year period to be as high as 2.9 under the high variable generation scenario.

Interconnections Seam Study