A South Dakota-based biofuels producer and a California energy startup have begun operations on one of the world’s largest thermal energy storage systems, situated directly adjacent to an ethanol processing facility in Big Stone City. The 5-gigawatt-hour installation absorbs excess, low-cost electricity generated by nearby wind turbines and converts it into heat within carbon blocks for later dispatch.
Wind generation frequently surpasses transmission capacity in the Great Plains, forcing grid operators to curtail production and waste renewable output. The new thermal storage facility captures that stranded electricity before curtailment occurs, storing it at extremely high temperatures until operators require additional grid support or industrial heat.
POET, a major ethanol manufacturer with operations throughout the Midwest, will utilize a portion of the stored thermal energy to power its ethanol plant processes. The company stated the system reduces reliance on natural gas for process heat, lowers operational costs, and maintains continuous production without depending on weather-dependent grid conditions.
Antora Energy developed the carbon-based storage blocks and the surrounding power conversion infrastructure. The California-based startup emphasized that the technology avoids reliance on critical mineral supply chains used in lithium-ion batteries, instead relying on abundant carbon materials and standard electromechanical components.
State and local officials described the Big Stone City project as a major economic and environmental advancement for the region. They noted the installation creates skilled technical jobs, strengthens local grid reliability, and serves as a scalable model for clean-energy integration across the Great Plains.
Energy sector analysts observe that thermal storage systems offer distinct advantages for regions with high renewable penetration and constrained transmission infrastructure. The POET and Antora partnership demonstrates how existing agricultural manufacturing facilities can integrate next-generation storage to stabilize local energy markets. MSI previously reported that grid-scale storage deployments are gaining traction across the Midwest as utilities seek to balance intermittent renewable output with baseload industrial requirements ….
Regional energy planners will monitor the facility’s dispatch reliability, round-trip efficiency, and maintenance performance over the coming twelve months. Data collected from the Big Stone City site will guide decisions on expanding carbon-block thermal storage to additional industrial and agricultural facilities throughout South Dakota and neighboring states.