Ameren Missouri has announced plans to develop a gas-fired, electricity-generating plant and power storage facility on the site of its former coal-fired plant south of Festus in Jefferson County.
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.”
Two operations
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.
“We will be tying into existing natural gas lines, installing new gas pipeline into the site specifically to serve these units,” said David Meiners, director of new gas generation for Ameren Missouri. “The units will have fuel oil backup.”
Two combustion units, each 400 megawatt capacity, will produce electricity, which will be used to back up Ameren’s energy supply grid at times of peak demand.
Gas generation of electricity is typically cleaner and more efficient than coal, according to the U.S. Energy Information Administration.
“Over the past 15 years, the U.S. electricity generation mix has shifted away from coal and toward natural gas and renewables, resulting in lower CO2 emissions from electricity generation,” the EIA website notes.
Meiners said gas-fired units are “a good alternative to coal in meeting the demands we have in this country.”
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 says 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.
“The Big Hollow facility will help ensure grid resiliency,” Meiners said. “That’s a driving aspect of the project.”
Quick turnaround
Ameren officials say there is a definite advantage to using the former Rush Island site, with its already-in-place infrastructure and transmission lines.
“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 cost and the timeline are both reduced by taking advantage of existing infrastructure,” Meiners said. “The turbine units are already on order and scheduled to be delivered in time to meet our construction timeline. Things we’d normally have to build out are already in place and ready to go.”
The former Rush Island Energy Center, a coal-fired electricity generating plant, operated for nearly 50 years on the site. 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.
The loss of the plant meant a big loss in revenue for the Jefferson R-7 School District. Ameren paid about $1.6 million annually in taxes to the district while Rush Island was in operation, according to superintendent David Haug, and the plant closing meant a $25 million loss in assessed valuation for the district.
But the announcement of the Big Hollow project should allow the district to move forward with improvement plans it has had on hold since the Rush Island retirement was announced.
“Our primary goal was to retain Ameren as a community partner,” Haug said. “We are pleased to continue this partnership with the announcement of the Big Hollow project.
“The future is looking very bright here.”
Meiners said Ameren is pleased to retain its relationship with the school and the county.
“Big Hollow will be a considerable investment, and will bring jobs, both construction and ongoing operations,” he said. “It’s too soon in the development process to give a number estimate, but based on the similar Castle Bluff Energy Center, we estimate a few hundred construction jobs.”
Meiners said Big Hollow will be staffed daily with both operations and maintenance personnel.
He said the new facility will incorporate industry standard safety measures.
“Ameren has more than 40 gas combustion units spread across nearly a dozen sites that we operate safely and reliably,” he said. “The Big Hollow units will be rolled into our existing fleet with operational and safety practices. We will definitely include the local fire department in training and awareness.”
Those who want to comment on the project have several ways to do so:
■ Contact the Office of the Public Counsel-Governor Office Building, 200 Madison St., Suite 650, P.O. Box 2230, Jefferson City, 65102-2230
■ Contact the Public Service Commission Staff, P.O. Box 360, Jefferson City, 65102
■ Call 866-922-2959 or 800-392-4211
■ Email mopco@opc.mo.gov or pscinfo@psc.mo.gov.
Ameren Missouri supplies power to approximately 1.3 million electric and 135,000 natural gas customers in central and eastern Missouri. The company’s service area covers approximately 60 counties and more than 500 communities, including the greater St. Louis area. For more information, visit Ameren.com/Missouri.