South Dakota has cemented its status as a regional energy hub with the launch of one of the world's largest thermal energy storage facilities. The 5-gigawatt-hour plant, a partnership between South Dakota-based POET and California's Antora Energy, is located adjacent to POET's ethanol plant in Big Stone City.
How the System Works
The facility captures excess, low-cost wind energy that would otherwise be wasted due to grid capacity limits. This energy is stored as heat in insulated carbon blocks reaching 4,000 degrees Fahrenheit. When needed, the heat is transferred via oil to produce steam that powers ethanol production machinery.
Andrew Ponec, CEO of Antora Energy, likened the process to a giant toaster: electricity from wind turbines heats carbon blocks (like toaster coils), which then generate heat to run industrial processes.
Economic and Environmental Benefits
- Improved efficiency: POET's ethanol plant gains a reliable sustainable energy source, reducing consumer costs at the pump.
- Boost for corn growers: Expanded ethanol production increases demand for locally grown corn.
- Reduced fossil fuel reliance: Enables greater storage of renewable energy, cutting fossil fuel use.
- Job creation: 300 construction jobs supported, with new full-time positions in Big Stone City.
Jeff Lautt, POET's president and COO, noted the system captures wind energy that otherwise has no home on the grid. The Big Stone plant produces 92 million gallons of ethanol annually.
Project Financing and Support
Ponec declined to reveal the total cost but noted that Antora has attracted hundreds of millions in private investment, led by Grok Ventures of Australia. The project received bipartisan political support, including from U.S. Senators John Thune and Mike Rounds, Representative Dusty Johnson, and Governor Larry Rhoden.
Rounds stated: "America's need for energy is rising year after year. This project will have a real economic impact in South Dakota while creating jobs and boosting domestic energy production."
Why Big Stone City?
The site was chosen for its existing POET biofuels plant, Otter Trail Power Co. facility, and its location as a major hub on the MISO power grid. Construction took less than a year, and the facility is already supplying power, with full operation expected by October.
Comparison with Lithium Battery Storage
Thermal storage differs from lithium-ion batteries: while batteries store electricity for a few hours, thermal storage holds energy as heat for much longer periods. South Dakota is also exploring lithium battery projects in Codington and Brookings counties.
Antora earns revenue by selling energy to POET, reducing the plant's natural gas use and carbon footprint. Lautt called it a "win-win-win" for efficiency, the environment, and the economy.
This story was originally published by South Dakota News Watch and distributed through a partnership with The Associated Press.
