EPRI, Southern Company and Storworks complete testing of the world’s largest concrete thermal energy storage pilot

Leading independent, non-profit energy research and development organization, EPRI in collaboration with Southern Company and Storworks has successfully tested a pilot concrete thermal energy storage (CTES) system at Alabama Power's C. Gaston Electric Generating plant (Gaston).

In what is said to be the largest such pilot in the world, the 10 megawatt-hour electric (MWhe) energy storage solution is charged using heat from supercritical steam generated by Gaston's Unit 5.

"Advancements in long-duration energy storage are key to unlocking the full potential of variable renewable energy resources on the path to net-zero," said Neva Espinoza, EPRI vice president of Energy Supply and Low-Carbon Resources.

"As the power sector navigates a highly complex transition, CTES could play an important role in efficiently delivering the reliable and affordable electricity society depends on."

The project received funding from the U.S. Department of Energy and the technology has been developed by Storworks. According to EPRI, the technology can be applied to existing or new thermal power plants, including coal, natural gas, nuclear, or concentrating solar power. The core technology can go beyond electric power to applications including decarbonizing industrial heat.

"We appreciate the vision and support from our partners that made this pilot demonstration possible," said Scott Frazer, co-founder of Storworks. 

"Low-cost long-duration energy storage is increasingly critical in the shift to low-cost intermittent renewable energy, and the Gaston project represents an important milestone in advancing the commercialization of our technology."

As designed, high-pressure steam from the power plant flows through tubes, heating the concrete, which stores the thermal energy until it is returned to the power plant by converting feedwater into steam to generate electricity in response to grid demand.

EPRI in an official statement emphasized that the CTES pilot system not only proved the technology's potential to store thermal energy for conversion to electricity when combined with thermal power plants but also exceeded the original goals of the project, as steam production at several pressure levels was demonstrated.

"More than 80 energy charge and discharge cycles were also successfully performed over 700 hours of total operation," EPRI stated.

The CTES system are capable of giving grid operators greater flexibility by allowing them to store energy when needed and providing it when it is most valuable. EPRI will continue to evaluate the feasibility of CTES and other long-duration energy storage options as part of the clean energy transition.

"As a leader in research and development, Southern Company is exploring the potential of CTES technology to help decarbonize electricity production," said Dr. Mark S. Berry, Southern Company Senior Vice President of Research, Environment And Sustainability.

"We are excited to be pioneering this groundbreaking research demonstration in collaboration with EPRI, Storworks, and our subsidiary, Alabama Power."