Ameren Missouri Plans Hybrid Energy Center to Enhance Reliability and Drive Clean Energy Future
Ameren Missouri, a subsidiary of Ameren Corporation (NYSE: AEE), has filed an application with the Missouri Public Service Commission to move forward with a landmark infrastructure project—the Big Hollow Energy Center in Jefferson County, Missouri. This initiative marks a significant milestone in Ameren’s generation investment strategy, combining an 800-megawatt (MW) simple-cycle natural gas plant with the company’s first large-scale battery storage system in a single location.
The project aims to ensure continued energy reliability, strengthen grid resilience, and prepare Missouri for a future of rising power demand.
A Balanced Strategy for the Energy Transition
“This is the next step to deliver on our strategy to invest in energy infrastructure for our customers’ benefit and provide a balanced generation portfolio,” said Mark Birk, chairman and president of Ameren Missouri. “As we transition our generation for the future, we’ll continue to serve our customers with the reliable energy they expect while also preparing for anticipated increases in demand.”
Ameren Missouri’s generation plan is grounded in the principle of flexibility—balancing renewable investments with dependable generation sources. The Big Hollow Energy Center exemplifies this principle. The natural gas portion is modeled after the company’s Castle Bluff Energy Center and will provide dispatchable power during extreme weather conditions—cold winter days, hot summer peaks, and times when intermittent renewables are unavailable.
At the same time, the inclusion of battery storage allows Ameren Missouri to adapt to fluctuations in renewable energy output while reducing stress on the grid during high-demand periods.
Large-Scale Battery Storage: A First for Ameren Missouri
The Big Hollow project will feature a 400-MW lithium-ion battery array—the utility’s largest energy storage investment to date. These batteries will store excess energy generated during off-peak times and release it when demand surges or when generation from renewable sources is low.
Because lithium-ion batteries can respond in seconds, they serve as fast-acting assets to stabilize the grid, making them particularly valuable during periods of system volatility. Once fully charged, the battery system is expected to provide power to thousands of homes for several hours.
This project aligns with Ameren Missouri’s long-term clean energy targets. The company has announced plans to build 1,000 MW of battery storage by 2030, ramping up to 1,800 MW by 2042. The Big Hollow facility is a cornerstone of this broader storage expansion strategy.
Infrastructure Optimization and Cost Efficiency
One of the most notable aspects of the Big Hollow Energy Center is its efficient use of land and resources. The site—already owned by Ameren Missouri—offers existing infrastructure and transmission line access. This advantage shortens construction timelines and reduces development costs, which can be passed on as savings to customers.
Moreover, although the gas generation and battery systems will operate independently, their co-location allows Ameren Missouri to maximize site utility while minimizing environmental and financial impact.
“It is crucial to have a balanced mix of generation technologies and equally important to strategically locate them across the region,” said Ajay Arora, senior vice president and chief development officer at Ameren Missouri. “This approach maximizes the energy output from these resources.”
Local Economic and Community Benefits
Beyond the technological innovation, the Big Hollow Energy Center represents a meaningful investment in Jefferson County’s economy and workforce. Once approved and constructed, the center is expected to generate new jobs and stimulate long-term economic activity in the region.
Rob Dixon, senior director of economic, community, and business development at Ameren Missouri, emphasized the company’s longstanding relationship with Jefferson County:
“We have collaborated with leaders across Jefferson County for years, and it’s exciting to locate the Big Hollow Energy Center and continue to invest in the community because it will bring jobs, support the Jefferson R-VII School District, first responders and others in the county.”
Community leaders echoed these sentiments, noting the project’s potential to drive both energy resilience and economic renewal.
“The Big Hollow Energy Center represents more than just an energy project; it’s a commitment to the future of Jefferson County,” said Dennis Gannon, Jefferson County Executive. “We’ve worked closely with Ameren Missouri over the past several years, and this forward-thinking investment will strengthen our local economy for generations to come. We’re proud to partner with Ameren Missouri to help power progress in our community.”
Maintaining a Strong Community Partnership
The Big Hollow Energy Center is also seen as a continuation of Ameren Missouri’s role as a valued community partner. This is especially significant in light of the planned October 2024 closure of the Rush Island Energy Center, which had raised concerns about local economic impacts.
“The Jefferson R-VII Board of Education and I deeply appreciate Ameren Missouri’s communication regarding the closure of the Rush Island Energy Center. The company has addressed every concern about its closure and the impact on our students, consistently treating the district with the utmost respect,” said Dr. David Haug, superintendent of the Jefferson R-VII School District.
“With the Rush Island Energy Center’s closure in October 2024, our primary goal was to retain Ameren as a community partner. We are pleased to continue this partnership with the announcement of the Big Hollow project.”
Preparing for the Future, Powering the Present
The Big Hollow Energy Center embodies Ameren Missouri’s commitment to a sustainable and reliable energy future. It is a prime example of how utilities can modernize their generation mix while continuing to meet the growing energy demands of communities, industries, and critical services.
With regulatory approval, the facility is expected to come online by 2028. By integrating flexible natural gas resources with rapid-response battery storage, Ameren Missouri is creating a robust, future-ready infrastructure designed to withstand the dynamic challenges of the energy landscape—be it extreme weather, shifting customer needs, or the continued integration of renewables.
