The Midcontinent Independent System Operator has selected a consortium of Ameren Transmission Company of Illinois, GridLiance Heartland and Dairyland Power Cooperative to develop, build, operate and maintain a major transmission project in Iowa.
ATXI and GridLiance will lead the development of this project and own it jointly with Dairyland once it is placed in service.
The East Adair – Minnesota/Iowa State Line – Arbor Hill – York Avenue (EASL) project is foundational to a new 765-kilovolt (kV) backbone that will deliver safe, reliable and affordable energy to Midwest communities, Ameren said.
"MISO selected the consortium through a competitive process after determining that its proposal offered the best overall value, based on its design, execution capabilities, regulatory experience and other key factors," an Ameren news release said.
ATXI is a subsidiary of Ameren, GridLiance Heartland is a subsidiary of NextEra Energy Transmission, LLC and Dairyland Power Cooperative is a Wisconsin-based cooperative that provides the wholesale electrical requirements for cooperatives and public power utilities in the Upper Midwest.
The total MISO estimated cost for this competitive transmission project is approximately $1.23 billion. ATXI, GridLiance, and Dairyland will have ownership stakes in the project of 42.5%, 42.5%, and 15%, respectively.
The EASL project includes the construction of one new 765-kV transmission line spanning approximately 187 miles, one 345/765-kV substation named East Adair, and two new 345-kV transmission lines spanning approximately 22 miles in total.
The 765-kV line will run north from the new East Adair Substation in southern Iowa to the Minnesota/Iowa state line. The first 345-kV transmission line will run south from East Adair and connect to Deadend East of York Avenue. The second 345-kV transmission line will run north from East Adair and connect to the existing Arbor Hill Substation, which is also in southern Iowa.
EASL is a competitive project in MISO's Long Range Transmission Planning Tranche 2.1 Portfolio, which was originally approved in December 2024.
The 765-kV scope of the project has an expected in-service date of June 1, 2034, while the 345-kV scope has an expected in-service date of June 1, 2032. The project will undergo the regulatory review process and thorough stakeholder and community engagement.
ATXI, GridLiance, and Dairyland were also selected earlier this year, along with the Illinois Municipal Electric Agency, to deliver the Sub T – Iowa/Illinois State Line – Woodford County (STIW) and Woodford County – Illinois/Indiana State Line (WIIL) projects. Those earlier projects are also part of the Tranche 2.1 Portfolio.
