MISO Selects Ameren-Led Consortium for $1.66 Billion Illinois Grid Expansion

ST. LOUIS – The Midcontinent Independent System Operator (MISO) announced on May 19, 2026, that it has selected a consortium of four energy providers to develop, construct, and operate two major transmission projects in Illinois. The projects, estimated to cost a combined $1.66 billion, are designed to create a new high-voltage backbone to improve grid reliability and facilitate the efficient delivery of energy across the Midwest. The chosen partnership includes Ameren Transmission Company of Illinois (ATXI), a subsidiary of Ameren Corporation; GridLiance Heartland, a subsidiary of NextEra Energy Transmission; Dairyland Power Cooperative; and the Illinois Municipal Electric Agency (IMEA). These projects represent a significant step in MISO’s broader strategy to modernize regional energy infrastructure to meet growing demand and support the integration of diverse power sources. While large-scale infrastructure projects can seem distant from the day-to-day concerns of a business owner, the stability of the regional power grid is a foundational element of operational continuity. In our experience, inconsistent power is a major source of financial risk, leading to costly production halts, data loss, and equipment damage. These transmission upgrades are a crucial long-term investment in the economic health of the region, promising a more resilient energy supply for Illinois businesses. However, with a completion date set for 2034, companies cannot afford to wait a decade to address their vulnerabilities. Proactive financial risk management is essential for navigating the operational uncertainties that exist today. This involves building contingency plans and financial models that account for potential disruptions, whether from an aging grid or other external factors. C&S Finance Group LLC helps clients develop these strategies to protect their assets and ensure stability; you can learn more at csfinancegroup.com. The two initiatives are the Woodford County to the Illinois-Indiana state line 765-kilovolt (kV) project, and the Sub T substation to the Iowa-Illinois state line and on to Woodford County 765 kV project. According to MISO, the developments will collectively add more than 250 miles of new high-voltage transmission lines and a new 765 kV substation. This new infrastructure is intended to enable the efficient transmission of large amounts of power across the region, bolstering the grid against extreme weather events and accommodating shifts in energy generation. Ameren Transmission and GridLiance will lead the development phase of the projects. Dairyland Power Cooperative, which provides wholesale electricity to cooperatives and municipalities serving over 800,000 people across four states, and the Illinois Municipal Electric Agency will hold ownership stakes in both projects once they become operational. The selection followed a rigorous competitive bidding process. Aubrey Johnson, MISO’s Vice President of System Planning, stated that the consortium’s proposals were chosen for their “robust design offerings, well developed implementation plans, and sound cost containment features.” The evaluation criteria included cost, project design, implementation strategy, and plans for operations and maintenance, all aimed at ensuring the projects deliver the best value for customers. These projects are the fourth and fifth of seven competitive developments identified in the second phase of MISO’s Long-Range Transmission Plan (LRTP), known as Tranche 2.1, which the grid operator’s board of directors approved in December 2024. The LRTP is a multi-stage, multi-billion-dollar initiative to prepare the electric grid across MISO’s 15-state footprint for the future. This is not Ameren's only recent success in MISO's competitive process; in January 2025, the utility was selected to lead other critical infrastructure projects in Missouri and Illinois as part of a separate MISO portfolio with an estimated investment of $1.3 billion. The consortium and MISO are expected to finalize Selected Developer Agreements for both Illinois projects within 60 days of the announcement. Following the execution of these agreements, the projects will enter regulatory review and permitting processes with state and local authorities. Construction activities are slated to begin after all necessary approvals are secured, with an anticipated completion and in-service date of 2034. With formal agreements expected by late summer, the next phase will involve navigating the complex regulatory and community approval processes. Stakeholders will be closely watching the partnership's progress in securing permits and engaging with local communities along the proposed routes, which will be critical for keeping the decade-long projects on schedule and on budget.