Before electricity is distributed to consumers, it must first be transmitted from its generation source (power plant or wind or solar farm) to the distribution grid. Transmission is often considered the “backbone” of the electricity delivery system, ensuring electricity supply reaches demand even from hundreds of miles away.1 The U.S. electric grid currently contains over 642,000 miles of high-voltage transmission lines and approximately 6.3 million miles of local distribution lines.2 Expanding transmission capacity is instrumental in sourcing new, high-quality renewable energy resources, and moving this renewable energy from where it is generated to where it is needed. Preventing region-wide blackouts and ensuring consistent, equitable access to electricity depends on updated transmission infrastructure and advanced transmission technologies.

Key Technologies

  • High-voltage transmission lines are the key to efficient energy transmission over long distances. Transmission lines with high-voltage capacity minimize energy loss as electricity is brought from supply source to consumer demand, as the lower current electricity is able to travel with a lower resistance. Transmission lines are typically supported by tall metal towers, compared to lower-voltage distribution lines generally supported by wooden poles covering much smaller distances.
  • Advanced transmission technologies can be separated into software and hardware solutions:
    • Sensor and Software Solutions, such as dynamic line rating and topology optimization controls, address short-term system problems by improving grid operations within the constraints of the physical hardware.3
    • Actuators and Hardware Solutions, such as direct current (DC) and alternative current (AC) power flow controllers, address the physical capabilities of the grid to provide more long-term reliability.

Potential Market Size & Timing

  • To meet net-zero scenarios, the capacity of the transmission system will need to at least double by 2030 and possibly triple by 2050.4 NREL estimates between 13,000 and 91,000 miles of new interregional transmission lines will be needed by 2035 depending on the scenario, including the Constrained, No Carbon Capture, and Infrastructure Renaissance scenarios. Assuming construction begins in 2026, 1,400 – 10,100 miles of new lines need to be deployed each year.
    • Even in lower transmission estimate scenarios where construction is more difficult and costly, NREL forecasts an increase in current domestic transmission capacity by 26%.
  • The National Academies of Sciences Engineering Medicine forecasts an even larger need, predicting that over the next three decades we will need to build over one million miles of new transmission lines to bring wind from the Midwest and solar from the Southwest to distant loads.5
  • NREL’s most successful low-cost net-zero scenarios demonstrate a clear relationship between transmission and wind, as wind generation is most dependent on new transmission capacity. For each projected 2035 scenario, increasing transmission capacity to enable low-cost wind is cheaper than focusing on regional resources with increased storage.6
    • Figure 1 above shows an increase in transmission capacity, by both AC and DC technologies using voltage source converters (VSC) and line-commutated converters (LCC) or back-to-back interties (B2B), in “wind-rich” regions of the U.S. between 2020 and 2035.


  • Siting and permitting challenges constricting the growth of transmission need to be addressed to meet the Biden Administration’s goal of net-zero electricity by 2035. Currently there is no eminent domain associated with building new power lines, unlike pipelines.
  • Aging infrastructure may be unable to meet increased electricity demand, generation additions or handle non-traditional generation sources such as intermittent wind or solar plants. Approximately 70% of transmission lines are over 25 years old.8
  • Higher infrastructure and technology costs can be a barrier to new capacity build-out.
  • System congestion without adequate planning and interventions can significantly raise costs.


  • Permitting reform that provides transmission projects with eminent domain or similar tools to secure the necessary right of ways for new transmission lines and ensure completion within a commercially reasonable time.
  • Department of Energy’s Building a Better Grid Initiative9 focuses on domestic deployment of “new and upgraded high-capacity electricity transmission lines,” with technical review committees for the DOE’s National Transmission Planning Study currently underway.10
  • Bipartisan Infrastructure Law provisions accelerating transmission:
    • Transmission Facilitation Program administering $2.5 billion in a revolving loan fund for high-capacity transmission projects.
    • Energy improvements in rural or remote areas provisions includes funds eligible for tools and projects which improve the cost-effectiveness of transmission and distribution systems, or address siting and upgrading transmission and distribution lines.11
  • Globally, an estimated $20 billion is allocated for transmission and distribution system spending between 2020-2023.12
  • Large-scale interconnectors will be integral to decarbonizing regions globally, with the REPowerEU plan investing EUR 29 billion for the development of interconnectors. This transmission technology can expand access to remote energy resources and further integrate renewables.13,14

NEMA Technologies

  • Transmission and distribution voltage regulators
  • Power & control cables
  • High voltage insulators


  1. Advanced Transmission Technologies Report – final as of 12.3 – FOR PUBLIC_0.pdf (
  2. Advanced Transmission Technologies Report – final as of 12.3 – FOR PUBLIC_0.pdf (
  3. Advanced Transmission Technologies Report – final as of 12.3 – FOR PUBLIC_0.pdf (
  4. The National Academies of Sciences Engineering Medicine, 2021. “Accelerating Decarbonization in the United States Technology Policy and Societal Dimensions.”
  5. Examining Supply-Side Options to Achieve 100% Clean Electricity by 2035 (
  6. Examining Supply-Side Options to Achieve 100% Clean Electricity by 2035 (
  7. Advanced Transmission Technologies Report – final as of 12.3 – FOR PUBLIC_0.pdf (
  8. Advanced Transmission Technologies Report – final as of 12.3 – FOR PUBLIC_0.pdf (
  9. National Transmission Planning Study | Department of Energy
  10. Oct 14, 2022, Technical Review Committee Meeting 2 | Department of Energy
  11.  BIL Provision: Energy Improvement in Rural and Remote Areas – Energy Communities
  12. Smart Grids – Analysis – IEA
  13.  Smart Grids – Analysis – IEA
  14. REPowerEU: affordable, secure and sustainable energy for Europe | European Commission (