Transmission

Before electricity is distributed to consumers, it must be transmitted from its generation source (such as a power plant, wind, solar farm) to the distribution grid. Transmission is often considered the “backbone” of the electricity delivery system, ensuring that 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.

• High-voltage transmission lines are crucial for efficient energy transmission over long distances. Transmission lines with high-voltage capacity minimize energy loss as electricity is transported from the supply source to consumer demand, as lower current electricity can travel with lower resistance. Transmission lines are typically supported by tall metal towers, compared to lower-voltage distribution lines, which are generally supported by wooden poles and cover much smaller distances.

• Advanced transmission technologies can be categorized 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 alternating current (AC) power flow controllers, address the physical capabilities of the grid to provide more long-term reliability.

• 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 The National Renewable Energy Laboratory (NREL) estimates that between 13,000 and 91,000 miles of new interregional transmission lines will be needed by 2035, depending on three modeled scenarios, including the Constrained, No Carbon Capture, and Infrastructure Renaissance. Assuming construction begins in 2026, 1,400 to 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, and Medicine forecast an even larger need, predicting that over the next three decades, we will need to build over 1 million miles of new transmission lines to bring wind from the Midwest and solar from the Southwest to distant loads.⁵

• NREL’s 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.

FIGURE 1. DECARBONIZING THE GLOBAL ECONOMY: NETWORK INVESTMENT PROFILE FOR DISTRIBUTION AND TRANSMISSION 2020-2050.

• 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, accommodate 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 rights-of-way for new transmission lines and ensure completion within a commercially reasonable time.

• The Department of Energy’s (DOE) Building a Better Grid Initiative 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.^9,10

• Bipartisan Infrastructure Law provisions accelerating transmission:

• The Transmission Facilitation Program administers $2.5 billion in a revolving loan fund for high-capacity transmission projects.

• Energy improvements in rural or remote areas provisions include funds eligible for tools and projects that 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 and 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

• Using existing rights-of-way corridors such as highways, railways, and pipelines to co-locate transmission can address some of the issues associated with the transmission siting and permitting process.¹⁵

NEMA Technologies

• Transmission and distribution voltage regulators
• Power & control cables
• High voltage insulators
• Power conversion devices
• Transformers
• Switchgear