For seventeen years, the idea of connecting New Mexico's powerful winds to California's power-hungry cities remained stuck in regulatory limbo. On September 1, 2023, construction finally began on SunZia, a $11 billion project that will become the largest clean energy infrastructure build in American history—a 550-mile high-voltage transmission line paired with the Western Hemisphere's biggest wind farm.
When operational in 2026, SunZia will deliver 3,000 megawatts of wind power to Arizona and California—more electricity than the Hoover Dam generates. The project marks a rare breakthrough in a country where nearly 2,600 gigawatts of renewable projects sit waiting for grid connections, and where the average transmission line takes over a decade to permit. Pattern Energy's success in navigating federal, state, and tribal approvals offers a template—or a cautionary tale about timeline—for the dozens of major transmission projects needed to decarbonize the American grid.
15 events
Latest: May 29th, 2025 · 12 months ago
Showing 8 of 15
JK to step
Tap a bar to jump to that date
Jump to
May 2025
Appeals Court Revives Tribal Challenge
LatestLegal
The Ninth Circuit Court of Appeals reinstates the tribal lawsuit, ruling that plaintiffs plausibly alleged the Interior Department failed to properly consult on whether the San Pedro Valley should be designated a historic property.
April 2024
Federal Court Dismisses Tribal Lawsuit
Legal
A Tucson federal judge denies the tribes' request for an injunction and dismisses the lawsuit challenging SunZia's permits.
January 2024
Tribal Coalition Files Federal Lawsuit
Legal
The Tohono O'odham Nation, San Carlos Apache Tribe, and Archaeology Southwest file a federal lawsuit alleging the Interior Department illegally approved permits without proper tribal consultation.
December 2023
$11 Billion Financing Closes
Financial
Pattern Energy closes $11 billion in non-recourse financing, the largest clean energy infrastructure financing in U.S. history, enabling full construction of both the transmission line and wind farm.
November 2023
Clean Power Alliance Signs 575 MW Agreement
Commercial
Clean Power Alliance, serving Southern California communities, signs a 15-year power purchase agreement for 575 megawatts of SunZia wind power.
Construction Paused Over Tribal Concerns
Legal
The Bureau of Land Management temporarily halts construction in Arizona's San Pedro Valley after the Tohono O'odham Nation and San Carlos Apache Tribe raise concerns about impacts to religious and cultural sites.
September 2023
Groundbreaking Ceremony in New Mexico
Construction
Secretary of the Interior Deb Haaland and federal, state, and local officials break ground on the SunZia transmission line at the East Converter Station site near Corona, New Mexico.
May 2023
Power Purchase Agreements Signed
Commercial
Pattern Energy announces long-term power purchase agreements with Shell Energy North America and the University of California system for portions of SunZia Wind's output.
Federal Government Issues Final Approval
Regulatory
The Bureau of Land Management issues the Record of Decision for SunZia, completing the National Environmental Policy Act review and authorizing construction on federal lands.
December 2022
New Mexico Approves Transmission Line
Regulatory
The New Mexico Public Regulation Commission grants approval for the SunZia transmission project after the company submitted enhanced application materials.
January 2021
Pattern Energy Acquires SunZia
Corporate
Pattern Energy purchases SunZia outright from Southwest Power Group, taking over development of both the transmission line and wind project.
March 2018
New Mexico Rejects Initial Application
Regulatory
The New Mexico Public Regulation Commission rejects SunZia's transmission line application and requests a more detailed submission.
November 2016
Arizona Corporation Commission Approves Route
Regulatory
After a 10-year planning process, Arizona regulators approve the transmission line's Certificate of Environmental Compatibility.
June 2008
Right-of-Way Application Filed
Regulatory
Southwest Power Group applies to the Bureau of Land Management for permission to build a major transmission line across Arizona and New Mexico.
June 2006
Southwest Power Group Begins Planning
Development
Utilities, developers, and government officials meet in the Southwest to discuss grid expansion. Southwest Power Group proposes a transmission line connecting New Mexico's wind resources to western markets.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
1 of 3
1964-1970
Pacific Intertie (1970)
The federal government built a 846-mile high-voltage direct current transmission line from the Columbia River dams in Oregon to Los Angeles, connecting the hydropower-rich Pacific Northwest to Southern California's growing electricity demand. At the time, it was the world's longest HVDC line.
Then
Los Angeles gained access to cheap hydroelectric power, reducing dependence on local fossil fuel generation.
Now
The Pacific Intertie remains operational today, transmitting up to 3,100 megawatts and serving as a model for long-distance renewable energy transmission.
Why this matters now
SunZia follows the Pacific Intertie template: connecting remote renewable resources to distant urban markets via HVDC technology. The six-year timeline from authorization to operation in the 1960s contrasts sharply with SunZia's 17-year development cycle.
2 of 3
2010-2018
Plains & Eastern Clean Line Collapse (2018)
Clean Line Energy proposed a 720-mile HVDC transmission line to carry 4,000 megawatts of Oklahoma wind power to Tennessee and the Southeast. Despite securing a federal participation agreement in 2016, the project failed to obtain state permits and landowner agreements across Arkansas.
Then
The Department of Energy and Clean Line mutually terminated their partnership in March 2018. The company sold off its project assets.
Now
Plains & Eastern became a cautionary tale about transmission development, demonstrating that federal support alone cannot overcome state-level opposition and landowner resistance.
Why this matters now
SunZia succeeded where Plains & Eastern failed, partly because Pattern Energy secured state approvals in both Arizona and New Mexico before seeking final federal authorization. The contrast illustrates why major transmission projects typically take decades.
3 of 3
2005-2023
TransWest Express Breakthrough (2023)
The Anschutz Corporation proposed a 728-mile HVDC line from Wyoming wind farms to Nevada, applying for federal permits in 2008. After 15 years of environmental review and route modifications, the Bureau of Land Management authorized construction in April 2023.
Then
Construction began in 2024, with the project designed to deliver 3,000 megawatts of Wyoming wind to the Western grid.
Now
TransWest and SunZia together demonstrate that mega-transmission projects can reach construction—but only with patient capital willing to wait two decades for returns.
Why this matters now
TransWest and SunZia broke ground within months of each other after similar 15-17 year development cycles. Their simultaneous progress suggests the renewable transmission logjam may finally be breaking.
