PSC Approves Ameren Big Hollow Project Agreement

Press Release

FOR IMMEDIATE RELEASE -- February 11, 2026
Contact: Sarah Fontaine (573) 751-9300
PR-26-55

PSC Approves Agreement in Ameren Big Hollow CCN Request

JEFFERSON CITY, Mo.--- The Missouri Public Service Commission (“PSC”) today approved an Agreement between Union Electric Company, d/b/a Ameren Missouri (“Ameren”) and the Staff of the Missouri Public Service Commission and granted Certificates of Public Convenience and Necessity (“CCN”) for the construction of a simple cycle combustion turbine generator (“CTG”) facility and a battery energy storage system (“BESS”), collectively known as the Big Hollow project.
The Big Hollow project is located in Jefferson County at the former site of Ameren’s coal-fired Rush Island Energy Center.  The property is presently owned by Ameren and will be interconnected to Ameren Missouri’s 345-kV transmission system located at the proposed project site. The BESS Project is a 400-megawatt (“MW”) battery energy storage system, and the CTG facility is an approximately 800-MW multi-unit simple cycle natural gas electric generation facility.

The Commission has traditionally referred to previous case law when analyzing CCN applications using the following criteria: (1) there must be a need for the service, (2) the applicant must be qualified to provide the proposed service, (3) the applicant must have the financial ability to provide the service, (4) the applicant’s proposal must be economically feasible and (5) the service must promote the public interest.

In the matter of this decision, the Commission reviewed the Agreement for the factors listed above, as well as reviewed filed testimony from parties in the case and public testimony from a local public hearing. The Commission ensured the Agreement weighed the balance of the need for sufficient generation to provide safe and reliable service, while ensuring rates are just and reasonable for customers.

The approved Agreement and Order included the following highlights:

• Ameren Missouri must retain, and provide to Commission Staff, all supporting eligibility documentation for any investment tax credit provided for in the Inflation Reduction Act.
• Ameren Missouri will file quarterly progress reports on the construction of the project.
• If the cost of the project changes by more than 15%, Ameren Missouri will notify the Commission and provide a description of the change in cost, reason for the cost increase, and how Ameren Missouri attempted to mitigate the cost change.
• If Ameren elects to utilize construction work in progress (“CWIP”) accounting in rate base as allowed by Senate Bill 4 (2025), Ameren must first request approval from the Commission and provide supporting analysis that the utilization of CWIP will be less costly to customers than traditional accounting methods.
• Ameren will provide information relating to the Big Hollow project in future triennial integrated resource planning (“IRP”) filings.

Case No. EA-2025-0238