The U.S. Department of Energy announced the Southern Spirit Transmission project in 2024, a 320-mile transmission line designed to connect Texas with Louisiana and Mississippi. The project aims to enhance grid resilience by enabling greater electricity sharing between the Texas grid and neighboring regions.

The U.S. bulk power system is divided into three major grid regions known as interconnections: the Eastern, Western, and ERCOT (Electric Reliability Council of Texas) systems. Very few transmission lines currently link these interconnections, limiting the ability of grids to support each other during emergencies.

In 2021, a winter storm caused the Electric Reliability Council of Texas (ERCOT) to implement the largest deliberate electricity shutoff in U.S. history. More than 4.5 million Texans lost power during the event. At the time, ERCOT was able to import only about 6% of its total electricity demand from neighboring systems, due in part to limited transmission capacity.

According to the Department of Energy, the Southern Spirit Transmission project could improve the Texas grid’s resilience during periods of high demand and extreme weather. If the line had been operational in 2021, it could have reduced the scale of power losses by roughly 15%, enough to keep electricity flowing to approximately 600,000 additional Texas homes during peak demand.

Pattern Energy is developing the Southern Spirit Transmission line. The project represents a targeted effort to address the longstanding lack of interconnection between ERCOT and the Eastern Interconnection, which includes Louisiana and Mississippi.

Federal standards require transmission providers to maintain sufficient electricity reserves to serve their own local customers safely. Only electricity above that required safety reserve threshold can realistically be shared with neighboring grids during an outage. In 2024, the Federal Energy Regulatory Commission directed transmission providers to report how they assess risks to transmission assets, how those risks affect system operations, and how they plan to mitigate them—including under extreme heat and cold.