Transmission

Transmission Developments in 2023

Amid calls for increasing transmission capacity, nearly two dozen major interstate transmission projects, and even more intrastate projects, are in various stages of development throughout the Western Interconnection today.

Bonneville Power Administration

In July, the Bonneville Power Administration (BPA) announced more than $2 billion in transmission projects designed to increase capacity and accommodate regional growth in the Pacific Northwest as well as new clean energy resources being built on the east side of the region, far from the population centers.

Six projects would reinforce existing major BPA transmission lines that run from the east side of the region to load centers such as Portland and the Puget Sound area. Several smaller projects near Seattle and Portland would reinforce transmission lines that deliver power to BPA customers who serve retail load in those areas. These projects are expected to be completed between 2025 and 2032; they still must undergo environmental review.

BPA is also working on four projects—one new transmission line and three substations—in central Oregon, where utilities are experiencing significant load growth in part from large commercial customers. These projects are part of BPA’s Evolving Grid effort, which is studying customer and regional transmission needs over the next two decades. Go here for more information on the Evolving Grid effort and summaries of these projects.

New Mexico Renewable Energy Transmission Authority

New Mexico’s New Mexico Renewable Energy Transmission Authority (RETA) is a co-developer on four projects that span more than 1,100 miles. It also was co-developer on the $150 million Western Spirit transmission line, a 345-kV line that went into operation in 2021, covering 155 miles and delivering approximately 800 MW of wind power from central New Mexico to Albuquerque.

Mora Line Project: This $83 million project, co-developed by Lucky Corridor, LLC, consists of two line segments, one 48 miles and 345 kV and the other a 66-mile, 115-kV segment. Its capacity is 182 MW, and it is expected to be operational in 2024, running from the northeast corner of the state to a Public Service of New Mexico substation in north-central New Mexico.

SunZia: A 525-kV direct current line that spans 550 miles from central New Mexico to south-central Arizona with the capacity to transport 3,000 MW of wind energy from a 3,500 MW facility in New Mexico. Construction on the $1.8 billion project, co-developed by Pattern Energy, began in summer 2023, and it’s expected to be operational in 2026.

RioSol: A 500 kV transmission line that follows the SunZia route from central New Mexico to south-central Arizona and will provide up to 1,500 MW of wind and solar power to both states. Construction on the $1.3 billion project, co-developed by RioSol, is set to begin in 2026, with plans to be in operation by 2028.

North Path: A 525-kV direct current line that will run 400 miles from wind and solar facilities in northeastern New Mexico to the Four Corners region. With a 4,000 MW capacity, it is expected to be operational in 2028. Invenergy is co-developer on the project.

Colorado

Colorado legislators created the Colorado Electric Transmission Authority (CETA) in 2021. An independent public body, it is charged with facilitating the expansion of transmission resources to enable the state to meet its clean energy goals. It has the authority to engage in transmission planning that would meet those goals, increase grid reliability, and aid in economic development. In 2023, the Colorado Legislature enacted legislation requiring CETA to study the need for expanded transmission capacity in the state. An initial report is due September 1, 2024, and the final report is due to the Legislature on January 31, 2025.

Power Path: Public Service Company of Colorado is developing the state’s Power Pathway, a 345-kV transmission system that will connect eastern Colorado to the Front Range in central Colorado and will carry the approximately 5,500 MW of new wind, solar, and other resources the utility plans to add through 2030. Construction on two segments began in October 2023.

PacifiCorp

PacifiCorp’s Energy Gateway Transmission Expansion Program consists of several projects that will add more than 2,300 miles of new high-voltage transmission lines through Wyoming, Utah, Idaho, and Oregon. Several of the projects have been completed. These remain under development:

Energy Gateway South: This 416-mile, 500-kV line will connect wind farms in Wyoming to southern Utah. It is under construction and scheduled for completion in 2024.

Boardman to Hemingway: A proposed 500-kV line that will run approximately 290 miles from eastern Oregon to southwestern Idaho. Idaho Power is leading the permitting efforts. Construction on the line is expected to begin in 2024 and finish in 2026.

Gateway West:  A collaborative project between PacifiCorp and Idaho Power, it calls for approximately 1,000 miles of new high-voltage transmission lines in Wyoming and Idaho. The line is expected to be completed in 2024.

Oregon and Washington

Cascade Renewable Transmission Project: This project, which recently started the permitting process, would travel from The Dalles to just outside Portland, running beneath the Columbia River.

Wyoming to Las Vegas

TransWest Express: Construction began in summer 2023 on this 732-mile high-voltage line that will run from a 3,000 MW, 600-turbine wind facility that is under construction in Wyoming, through Colorado and Utah, to near Las Vegas, with conversion from direct to alternating current in central Utah. The power will be available for use in California, Arizona, and Nevada when the line is completed in 2027.

Arizona to Southern California

Ten West Link: This 500-kV line will run 125 miles from central Arizona to southern California. Construction began in early 2023 and the project is set to be online in May 2024. The new line will connect new solar and storage resources in Arizona with population centers in the two states.

Nevada, Idaho, and Utah

Greenlink West: The Bureau of Land Management (BLM) continued its environmental review of the Greenlink West Transmission Project, a system of 525-, 345-, 230-, and 120-kV electric transmission facilities located across approximately 423 miles of private, state, and federal lands between northern and southern Nevada.

Greenlink North: Scheduled for completion in late 2028, this 525-kV line will run approximately 235 miles from Ely, Nevada to Yerington, Nevada

Cross-Tie: The BLM initiated an environmental review of the proposed Cross-Tie 500-kV Transmission Project, a 214-mile, 1,500-MW, 500-kV, high-voltage alternating current transmission line that would run between central Utah and east-central Nevada. In October 2023, the DOE selected this project to enter into capacity contract negotiations as part of the Transmission Facilitation Program (TFP), a $2.5 billion revolving fund that was part of the Bipartisan Infrastructure Law.

SWIP-North: The first two phases of this three-phase project are in operation. Phase III will run 285 miles from Twin Falls, Idaho, to Ely, Nevada. It is scheduled to be online by the end of 2027. In December 2023, CAISO's board of governor's approved inclusion of the project into its 2022-2023 transmission portfolio.

Arizona and New Mexico

Southline Transmission Project: The first phase of this project is planned to span 175 miles from Hidalgo County, New Mexico, to Pima County, Arizona, addressing the need for increased transfer capability in the Southwest. In October 2023, the DOE selected this project to enter into capacity contract negotiations as part of the TFP.

The projects shown were selected because they are under construction, are DOE funding candidates, or are included in WECC's path rating process. This is not a comprehensive list of transmission projects under development in the Western Interconnection, and some of these projects may not be built.