National Transmission Needs Study: Draft for Consultation and Public Comment
U.S. Department of Energy, Office of Electricity01 Jul 2026public-domainRead the original
Work of the US federal government, not subject to domestic copyright. Carries the standard federal information-quality statement under Public Law 106-554. This is a DRAFT out for public comment — label it as draft and expect figures to change in the final version.
The Department of Energy's draft 2026 National Transmission Needs Study assesses present and expected transmission constraints across US regions. It records roughly 85,000 circuit-miles of transmission above 69 kV newly built, rebuilt or upgraded between 2016 and 2024, at a steady annual rate of about 8,700 to 12,500 circuit-miles through 2023. Incumbent utilities and transmission owners built about 98 percent of that mileage. Reliability was the largest single driver at roughly 40 percent of circuit-miles, with aging infrastructure, load growth and generator interconnection making up much of the remainder. The study puts congestion costs at about 11 billion dollars in 2023 and notes most congestion cost is concentrated in around 5 percent of hours. It flags accelerating load growth from data centre construction, and identifies cross-interconnection links — particularly ERCOT to its neighbours — as carrying some of the largest price differentials in the country.
Extract
"85,000 circuit-miles of newly constructed, upgraded, or rebuilt transmission lines rated above 69 kilovolts (kV), which were energized between 2016 and 2024." "Between 8,700 to 12,500 circuit-miles were installed each year from 2016 to 2023, demonstrating a relatively steady pace of transmission investment." "Incumbent utilities or transmission owners dominated the transmission facility development space nationwide, building 98% of all circuit-miles between 2016 and 2024." "Transmission congestion increases the average wholesale price of electricity, with congestion costs estimated to have been $11 billion in 2023." "The majority of transmission congestion costs are concentrated in 5% of the hours, particularly during times with significant day-ahead to real-time market price variance." "Cross-interconnection links from ERCOT to neighboring regions show some of the highest LMP differentials from $31 per megawatt-hour (MWh) to $48/MWh."
U.S. Department of Energy, Office of Electricity · public-domain · Read the original
The MyGreenSuit briefing
Commentary by MyGreenSuit, not the words of U.S. Department of Energy, Office of Electricity.
The 98 percent figure is the one to sit with: incumbent utilities and transmission owners built 98 percent of all new transmission mileage between 2016 and 2024.
Now set that beside DOE's own conclusion about where the highest-value lines are — interregional, and specifically the links between ERCOT and its neighbours, where price differentials run $31 to $48 a megawatt-hour. Those are precisely the lines no single incumbent has a reason to build, because the benefit lands on customers in somebody else's territory and the cost recovery is a fight.
That is not a technology problem or a permitting problem. It is an incentive problem, and it has been correctly diagnosed in federal documents for more than a decade without being solved.
One more number worth carrying: $11 billion of congestion cost in 2023, most of it concentrated in about 5 percent of hours. Congestion is not a chronic condition. It is a small number of very expensive afternoons.
This is a draft out for public comment, so treat the figures as provisional and check them against the final study.