The Missouri Public Service Commission on Feb. 11 approved Ameren Missouri’s plan to build a new natural gas plant and battery storage facility on the site of its former coal-fired plant south of Festus.
On June 27, the company filed an application with the Missouri Public Service Commission for the project, called the Big Hollow Energy Center, to be located on the site of the former Rush Island Energy Center, which closed in October 2024.
“The Big Hollow Energy Center represents more than just an energy project; it’s a commitment to the future of Jefferson County,” Jefferson County Executive Dennis Gannon said in a written statement. “This forward-thinking investment will strengthen our local economy for generations to come.”
The project will consist of two parts: an 800-megawatt, multi-unit natural gas generation facility with fuel oil backup, plus a 400-megawatt lithium-ion battery installation. While the two facilities will share the 500-acre site, they will be operated independently, Ameren reported.
With regulatory approval in place, the Big Hollow Energy Center is expected to be ready to serve customers beginning in 2028, Ameren officials said in a statement. The natural gas portion of Big Hollow will be designed to deliver energy during periods of peak demand, while also backing up the grid when renewable energy generation is otherwise unavailable, Ameren officials said.
The site plan also calls for a 400-megawatt battery storage facility, where excess energy produced in off-peak situations can be stored and then used in times of higher demand. Ameren has said the batteries are a “fast-acting asset,” meaning their stored energy can be available almost immediately when increased demand happens. This helps to stabilize the electrical grid by smoothing out fluctuations in supply and demand, especially with the increasing use of intermittent renewable energy sources.
“With timely regulatory approval, the energy center will be ready to serve as a reliable backup source of energy for customers in 2028,” the company reported.
The former Rush Island Energy Center, a coal-fired electricity generating plant, operated for nearly 50 years. At its peak, the plant employed more than 200 workers and generated just under 1,200 megawatts of power. Ameren began some years ago phasing out coal plants, as recommended by the Environmental Protection Agency, because of emission concerns. In late 2022, the company announced the Rush Island plant, scheduled to operate through at least 2039, would be retired in 2024.