DETROIT — MISO will start evaluating its South region for long-term transmission needs in 2026, beginning with Louisiana and possibly a lighter touch than used in the Midwest, the RTO announced before its Board of Directors on Sept. 16.
RTO planners told the board’s System Planning Committee they will approach the South with a “collaborative, investigative approach” and an eye on reliability and load growth.
MISO South never has had a successful, regionally cost-shared transmission project. MISO’s approximately $32 billion of long-range transmission projects approved over two portfolios in 2022 and 2024 have been confined to its Midwest region.
“We strongly suspect that while MISO South long-range planning will rely on the same tariff framework, it will have different viewpoints and different requirements,” Executive Director of Transmission Planning Laura Rauch told the committee.
MISO plans to start with modeling and what it calls the “South Load Pocket Risk Assessment” to inform planning. The RTO said it will use its updated, 20-year transmission planning futures in South planning once it’s done reformulating them. The transmission futures are due to be completed in early 2026. (See MISO Seeking Realistic Gen Buildout for Tx Planning Futures.)
Rauch said MISO will focus first on Louisiana’s needs “knowing that there are challenges” with load pockets and large load additions in the state. She said the RTO would develop a detailed scope of work for the South with stakeholders.
MISO said the load pocket assessment would estimate the risk of load shedding, with an initial focus on the Downstream of Gypsy load pocket in southeastern Louisiana, where load shedding occurred in late May.
Louisiana Public Service Commissioner Davante Lewis has said the Memorial Day weekend load shed event in New Orleans demonstrates the state needs more transmission capacity in and around the Downstream of Gypsy load pocket, which predates Entergy’s inclusion into MISO. (See MISO Debates What-ifs, Vows Improvements in Front of La. PSC After Load Shed.)
MISO South contains four major load pockets: Western, in East Texas; West of the Atchafalaya Basin, in East Texas and southwestern Louisiana; and Amite South and Downstream of Gypsy, in southeastern Louisiana.
Rauch said MISO’s early modeling could uncover issues where generation solutions — not new transmission — would be more appropriate. She said the RTO aims for solutions that South members “could pick up on and run with.”
MISO also said it plans to discontinue use of the word “tranche” to refer to the series of long-term portfolios. “Tranche 1” and “Tranche 2” referred to the first, $10.4 billion long-range portfolio and the second, $21.8 billion portfolio, respectively.
The Alliance for Affordable Energy’s Yvonne Cappel-Vickery said she hoped the phaseout of the word doesn’t mean that MISO South long-range planning would be “less robust” than in the Midwest.
At a Sept. 17 meeting of the Advisory Committee, Wisconsin Public Service Commissioner Marcus Hawkins asked when MISO might address its Midwest-South transfer constraint. The RTO originally said it would concentrate on the constraint in a fourth long-range transmission portfolio.
“Today, there certainly is some congestion on the North-South boundary,” said Jennifer Curran, senior vice president of planning and operations. But she added that as issues evolve in MISO, adding capacity on the constraint has decreased in urgency.
“I don’t think it’s a near-term priority economically or for reliability. But certainly, we will keep an eye on it.”
