Ameren Missouri Proposes Hybrid Energy Center to Support Future Grid
27th June 2025, St. Louis – Ameren Missouri, a part of Ameren Corporation has announced a historic proposed energy project to enhance Missouri’s electric grid in response to growing demand. The company submitted an application to the Missouri Public Service Commission requesting permission to build the Big Hollow Energy Center in Jefferson County.
The project would be the first of its kind to be constructed by Ameren Missouri, combining a 800-megawatt (MW) simple-cycle natural gas facility with a 400-MW battery energy storage system. If all approvals are received in a timely manner, the construction of this hybrid facility is expected to be completed by 2028 and is part of Ameren’s generation investment strategy.
“This represents a major step in fulfilling our promise to Missouri customers to provide reliable, resilient energy,” said Mark Birk, interim chairman and president of Ameren Missouri. “As energy demands continue to rise, this center is designed to support the grid in extreme conditions and in the heat of summer.”
The gas-powered portion of the facility will be similar in design to the Castle Bluff Energy Center. It is intended to generate energy in extreme cold, or the heat of summer, when demand is high, or when renewable generation is unable to provide enough energy to customers.
Ameren Missouri’s first large-scale battery storage system will also be co-located at the Big Hollow site. Using lithium-ion technology the batteries can store energy during low-demand times and discharge it during peak periods. This feature makes it a fast and flexible backup asset that can help stabilize the grid
The battery system once fully charged could power thousands of homes for several hours, giving Ameren the ability to react quickly to spikes in electricity usage or shortfalls in renewable production
Ajay Arora, Senior Vice President and Chief Development Officer at Ameren Missouri, said, “Locating both systems at one site maximizes existing infrastructure which reduces cost and time. This design is very efficient and customer friendly.”
Rob Dixon, senior director of economic and community development at Ameren Missouri, added that the project will generate jobs and long-term economic support for Jefferson County. It will benefit local schools and public services like police and fire departments
Dennis Gannon, Jefferson County Executive, shared his support for the project. “Big Hollow is more than a power facility it is a investment into the future of our community. We are excited to see Ameren Missouri take this step,” he said
The site already owned by Ameren, has access to transmission lines which will help speed up construction and minimize environmental impact
This proposal also follows Ameren’s plan to expand battery storage capacity to 1,000 MW by 2030 and 1,800 MW by 2042, ensuring the company is well positioned for Missouri’s clean energy future
The project reflects Ameren’s long-term vision to balance innovation, reliability, and community development in the state’s energy landscape.
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