Ameren Missouri Receives Approval To Build 800 MW Big Hollow Energy Center With State’s First Large-Scale Battery Storage In Jefferson County

Ameren Missouri, a subsidiary of Ameren Corporation, has received approval from the Missouri Public Service Commission to move forward with the development of the Big Hollow Energy Center, a new hybrid energy facility that will support reliable electricity service for residential, commercial, and industrial customers across the state. This approval authorizes the construction of an 800-megawatt simple-cycle natural gas facility that will operate alongside Missouri’s first large-scale battery storage installation located on the same site in Jefferson County. Once completed, the Big Hollow Energy Center will integrate into Ameren Missouri’s statewide generation system and play a critical role in supporting dependable electric service across the company’s service territory.

Michael Moehn, group president of Ameren Utilities, said the approval advances an important investment in reliability for all customers. He emphasized that Big Hollow will help ensure the company can meet rising electricity demand while maintaining a stable and dependable grid. The project is expected to be operational in 2028 and will function similarly to the Castle Bluff Energy Center, with the natural gas facility designed to operate during high-demand periods—such as extreme summer heat or severe winter cold—and provide backup generation when renewable energy output is limited.

A central component of the project is Ameren Missouri’s first utility-scale lithium-ion battery installation, a planned 400-megawatt storage system capable of responding within moments to customer needs. When fully charged, the batteries will be able to power thousands of homes for several hours, offering a fast-acting resource that enhances grid stability and supports overall reliability, particularly during times of peak demand. This facility is part of Ameren Missouri’s broader strategy to expand battery storage, with plans to add 1,000 megawatts by 2030 and a total of 1,800 megawatts across multiple sites by 2042.

Although the natural gas and battery facilities at Big Hollow will operate independently, they will share and build upon existing Ameren Missouri infrastructure, which will help streamline construction and reduce overall costs for customers. According to Ajay Arora, senior vice president and chief development officer at Ameren Missouri, the combination of quick-start natural gas generation and large-scale battery storage will add flexibility and resilience to the state’s energy system. He stated that the project will play an essential role in providing reliable service to homes and businesses during periods of high demand and shifting system conditions.