Pattern Energy Group LP's proposed Southern Spirit transmission line, which promises to connect the largely isolated Texas electric grid to the US Southeast, still faces hurdles ahead of construction after a decade of development.
If approved, the 320-mile, 525-kV high-voltage direct-current transmission line, capable of carrying approximately 3,000 MW, is set to be completed in 2029 and could enter commercial operation the same year, according to S&P Global Market Intelligence data and Pattern Energy. The line would connect the Electric Reliability Council of Texas Inc. and Southeastern transmission grids, stretching from the Texas/Louisiana border across northern Louisiana and extending into Mississippi, according to Pattern Energy.
The project, in which Pattern Energy plans to invest $2.6 billion, aims to enhance reliability during extreme weather and high demand. It will have the capacity to transport power in either direction along the line, allowing sharing between grids.
Pattern Energy is doing survey work, right-of-way acquisition and permitting for the Southern Spirit project, Adam Renz, the company's director of project development, told S&P Global Commodity Insights on Feb. 15.
Pattern Energy is targeting a full construction start for the project in 2026. The line would connect to the ERCOT grid by way of the Rusk-Panola transmission project, a 38-mile, 345-kV line linking two new substations. The Panola substation, at the Texas/Louisiana border and interconnected with a converter station to be connected to the Southern Spirit line, is to be developed by Garland Power & Light, a utility owned by the city of Garland, Texas.
Under its former name, Southern Cross, the project received Federal Energy Regulatory Commission approval in 2014 and approval from Texas regulators roughly two years later. Pattern Energy submitted applications to the Louisiana Public Service Commission and amended its 2017 application to the Mississippi Public Service Commission in 2023.
If Pattern Energy secures those regulatory approvals, the company will work to secure permits for the final project route, Renz said.
"The transmission project isn't a done deal," said Simon Mahan, executive director of the Southern Renewable Energy Association.
Utility concerns
In October 2023, Entergy Corp., which operates utilities across Arkansas, Louisiana, Mississippi and Texas, filed testimony in Mississippi objecting to aspects of the Southern Spirit plan. (Mississippi PSC Docket 2017-UA-79)
While subsidiary Entergy Mississippi LLC does not object to the project as a whole, Entergy spokesperson Neal Kirby said the company is concerned about "uncertainties" associated with the interconnection and operation of a transmission line that would connect ERCOT and the Mississippi grid for the first time. The proposed line would terminate at a converter station in Choctaw County, Miss., northeast of Jackson, Miss., the state capital.
Entergy Mississippi's goal in pending proceedings before state regulators is to ensure the proposed transmission project "does not adversely impact or harm our customers or customers of other Mississippi utilities," Kirby told Commodity Insights.
For example, Entergy said that neither Southern Spirit nor the Midcontinent ISO have provided analyses to calculate the projected impact of the project on Mississippi customers within the MISO market.
MISO's role in evaluating the Southern Spirit project is to conduct studies necessary for interconnection, allowing for the engineering requirements and costs associated with Southern Spirit to be determined, Mahan said.
The existing Entergy Mississippi transmission system is also not designed to inject or withdraw the amount of bidirectional power that could flow on the Southern Spirit transmission line, according to Kirby.
Southern Spirit has so far not identified necessary system upgrades, including the potential for additional transmission lines seeking new rights-of-way, Kirby said.
As a result, Kirby said Entergy Mississippi believes the evidence before the Mississippi Public Service Commission is "insufficient to support a finding of public convenience and necessity," which is required for the project to move forward in the state.
Entergy Mississippi has asked that state regulators postpone their decision on the proposed Southern Spirit line until more information on those concerns is provided, Kirby said.
Responding in the Mississippi PSC proceeding, Pattern Energy representatives, in testimony filed November 2023, called Entergy's concerns and objections "not well-founded, particularly those that suggest or speculate as to some harm to [Entergy Mississippi] ratepayers." They described Entergy as "erroneously seeking to impose on the [project] requirements that might be appropriate for a traditional utility" but are not required for this project.
MISO will determine costs that Pattern Energy should bear as a result of its interconnection of the proposed transmission line, Pattern Energy representatives said in their testimony. Any costs required to upgrade MISO infrastructure to accommodate sending or receiving power from Southern Spirit will be paid for by Pattern Energy, Renz said.
"Working with utility partners to help them understand the unique grid-enhancing attributes of a project is a key part of the permitting process," Renz said. "Helping Entergy and others to understand how [Southern Spirit] would interact with their existing system is a critical task. We continue to believe this line will improve reliability and bolster economic development without using a single dollar from [Mississippi] ratepayers."
Some of Entergy's particular concerns about Southern Spirit are hypothetical or already handled through typical MISO interconnection processes, Mahan told Commodity Insights.
For example, Entergy questioned where the full 3,000 MW of power will be injected into the MISO system, though the Southern Spirit project has only filed for 1,500 MW of interconnection in MISO, according to testimony filed with state regulators. The other 1,500 MW could interconnect with Southern's service territory.
Entergy said it was concerned that its local gas plants could be ramped down as a result of the transmission project. A January 2024 analysis by the National Bureau of Economic Research concluded that some large utilities have incentives to oppose transmission projects because greater market integration would harm operating profits. Entergy Louisiana LLC and Entergy Arkansas LLC stood to lose a combined $930 million in operating profits in 2022 from improved grid integration in MISO South, according to the bureau's analysis.
Southern could also have an interest in protecting its generation assets from competitive transmission, Mahan said, but so far, the company has not submitted testimony to object to the project in Mississippi.
While Entergy has expressed concerns, Renz said Pattern Energy has not had any formal utility opposition filed in either of its state regulatory proceedings for the Southern Spirit project.
Transmission opposition a protective move
Investor-owned utilities in the Southeast, including Entergy and Southern Co., have "spent years undermining efforts to expand high-voltage transmission in an effort to entrench their monopolies, preserve the value of their fossil fuel assets and limit the introduction of lower-cost renewable energy from outside their service territories," the Energy and Policy Institute, a frequent critic of investor-owned utilities, said in a Feb. 7 report. The report cited a finding by the Energy Systems Integration Group, a nonprofit group focused on energy systems integration, in a 2022 analysis projecting that Southern Spirit could save Southern Co. and ERCOT more than $150 million.
Efforts to better integrate the Southeastern regional grid and improve power exchanges have been slow to develop, with the Southern Energy Exchange Market seeing limited success in its first year.
US Sen. John Hickenlooper (D-Colo.) and Rep. Scott Peters (D-Calif.) filed the Building Integrated Grids with Inter-Regional Energy Supply Act, known as the BIG WIRES Act, in September 2023. The bill would require regional electric grids to have the ability to transfer about 30% of their peak load capability to neighboring grids to "fortify the critical energy infrastructure of the United States while lowering the cost of living for families." The bill has not advanced out of the Energy and Natural Resources Committee.
While ERCOT would be exempt from the proposed legislation, Entergy and Southern Co. have registered to lobby on the bill, according to federal disclosures.
In its report, the Energy and Policy Institute criticized Southern and Entergy for regularly opposing national standards or rulemakings aimed at increasing transmission in federal proceedings, and seeking to limit transmission growth in other jurisdictions.
"Southern Company is experiencing exceptionally high levels of demand growth, so perhaps the company would be excited to have access to the diversified resources in Texas to help serve the new load," Mahan said, adding "It is the role of state regulators to ensure the best outcomes for their state, regardless of incumbent opposition."
Southern Co. did not respond to a request for comment.