Southern Spirit Transmission

Overview

A 3,000 MW DC Line Would More Than Double ERCOT's Outside Ties

Southern Spirit Transmission, formerly Southern Cross, is a high-voltage direct-current (HVDC) line developed by Pattern Energy. It starts at the Texas-Louisiana border and runs about 320 miles through Louisiana to Mississippi, with converter stations in western DeSoto Parish, Louisiana, and Choctaw County, Mississippi, and a 500 kV switching station in Mississippi.

In Texas the line connects through the Rusk to Panola Transmission Project, a roughly 40-mile, 345 kV line built with Garland Power & Light. ERCOT (the Electric Reliability Council of Texas) can import at most about 1,220 MW today across its existing DC ties to the Southwest Power Pool (SPP) and Mexico, so 3,000 MW would more than double outside capacity.

Regulation

A DC Tie Keeps ERCOT Outside FERC Jurisdiction

ERCOT runs asynchronously from the Eastern and Western interconnections, which keeps most of the Texas grid outside FERC (Federal Energy Regulatory Commission) wholesale jurisdiction. A DC line moves power between grids without synchronizing them. FERC's May 2014 order directing interconnection and transmission service for the project was written to leave ERCOT's status intact, and in October 2024 ERCOT and the PUCT (Public Utility Commission of Texas) publicly rejected reports that the line would bring Texas under FERC.

In October 2024 the Department of Energy (DOE) selected Southern Spirit for up to $360M under the Transmission Facilitation Program, a capacity contract funded by the 2021 Bipartisan Infrastructure Law. Pattern recovers its investment through tariffs on power moved across the line instead of through utility rate bases.

State approvals have moved slower than the federal ones. Pattern filed for route approval with the Louisiana Public Service Commission and an amended application with the Mississippi Public Service Commission in February 2023. Louisiana passed a 2024 law limiting eminent domain for lines that do not serve Louisiana or carry grid-operator approval, and Entergy Mississippi raised cost and reliability concerns with Mississippi regulators.

Reliability Case

Winter Storm Uri Exposed How Little Power ERCOT Can Import

During Winter Storm Uri in February 2021, which Texas officials tied to 246 deaths, ERCOT's maximum import capability was 1,220 MW, of which 820 MW came from SPP. Mexico's grid operator, CENACE, cut exports to Texas after Texas restricted gas exports to Mexico. Critics such as the Texas Public Policy Foundation argue neighboring grids were short of power during the same storm.

Westbound flows would carry Southeastern gas and nuclear output into Texas during peaks; eastbound flows would move surplus West Texas wind, such as output from Roscoe, to MISO (the Midcontinent Independent System Operator) and Southeastern utilities. ERCOT's large-load queue reached about 474.7 GW in June 2026, mostly data centers, which adds weight to any new import path.

Developer

Pattern Energy Just Finished a Line of the Same Size in the Southwest

Pattern inaugurated SunZia Transmission in June 2026: a 550-mile, ±525 kV, 3,000 MW line carrying New Mexico wind to Arizona, built with Hitachi Energy voltage-source converter (VSC) HVDC Light technology. Pattern earlier built the TransBay Cable under San Francisco Bay and the 155-mile Western Spirit line in New Mexico.

China runs the world's largest HVDC network, built by State Grid Corporation of China, including the ±1,100 kV Changji-Guquan line rated at 12 GW. US projects such as Southern Spirit and SunZia buy converter stations from Hitachi Energy, Siemens Energy and GE Vernova.

Constraints

State Approvals and Land Rights Set the Schedule

Pattern's April 2025 fact sheet moved full construction to 2029 and service to 2032. Remaining steps include Mississippi and Louisiana approvals, right-of-way across roughly 320 miles, the Texas-side Rusk to Panola build and converter supply. DOE has not published an update on the Southern Spirit capacity contract since the 2024 selection.

Related coverage

Related Coverage

• ERCOT Energy Sovereignty
• ERCOT Large Load Interconnection
• Texas BESS Concentration
• Roscoe Wind Complex
• Samson Solar Energy Center
• Texas Energy Nexus