Ameren, GridLiance, Dairyland And IMEA Chosen To Develop New High-Voltage Grid Backbone For The Region

The Midcontinent Independent System Operator (MISO) has chosen a group of four energy organisations—Ameren Transmission Company of Illinois (ATXI), which is part of Ameren Corporation; GridLiance Heartland, a subsidiary of NextEra Energy Transmission; Dairyland Power Cooperative; and the Illinois Municipal Electric Agency (IMEA)—to develop, construct, operate, and maintain two major transmission projects in the Midwest.

ATXI and GridLiance will take the lead in developing both projects, while Dairyland and IMEA will become part-owners once the projects are completed and placed into service.These two projects, known as the Sub T–Iowa/Illinois State Line–Woodford County (STIW) project and the Woodford County–Illinois/Indiana State Line (WIIL) project, will form the beginning of a new 765-kilovolt (kV) transmission backbone.

This new backbone is designed to strengthen the region’s electric grid, improve reliability, and deliver cost-competitive energy to communities across the Midwest for many years.The STIW project involves building two new 765-kV transmission lines stretching roughly 149 miles. The first line will run from the Woodford County Substation westward to the Iowa/Illinois state line. From there, a second 765-kV line will continue west toward the Sub T Substation in Iowa.

The estimated cost for the STIW project, according to MISO, is about $940 million.The WIIL project includes two additional 765-kV transmission lines covering a total of 88 miles, along with a new 765/345-kV substation. One of the lines will extend east from the existing Woodford County Substation in central Illinois to the Illinois/Indiana state line. The other line will run northeast for approximately 1.5 miles from the Woodford County Substation toward the existing Collins Substation, where it will connect to another 765-kV line segment.

MISO estimates the cost of this project at around $718 million.Ownership of both projects will be divided among the participating organisations, with ATXI and GridLiance each holding a 43 percent share, Dairyland Power Cooperative holding 11 percent, and IMEA owning the remaining 3 percent.Leaders from each organisation expressed strong support for the collaboration. ATXI chairman and president Shawn Schukar said that the partnership will help deliver infrastructure that strengthens the grid and creates long-term value for customers.

Matt Valle, president of NextEra Energy Transmission, described the projects as essential for creating a stronger and more resilient transmission network for the Midwest. Dairyland’s executive vice president and chief operating officer, Ben Porath, stated that the cooperative is pleased to help ensure long-term reliability for the region.

IMEA’s president and CEO, Doug Brown, emphasised that greater transmission capacity is crucial for improving grid resiliency, integrating new energy resources, and supporting economic development.Both the WIIL and STIW projects are part of MISO’s Long Range Transmission Planning Tranche 2.1 Portfolio, which received approval in December 2024. After undergoing the necessary regulatory reviews and community engagement processes, the projects are expected to enter service in 2034.