The Electric Power Research Institute (EPRI) said it will lead a $5 million pilot project to test concrete thermal energy storage (CTES).

Participants will design, construct and test a CTES system to demonstrate the technology’s potential to store thermal energy for conversion to electricity when integrated with thermal power units.

As designed, high-pressure steam from a power plant will flow through tubes, heating the concrete modules. Those modules will store the thermal energy until it is returned to the power plant to generate electricity in response to grid demand.

The pilot project will test modules similar in size to those expected to be used in larger-scale commercial applications.

The 10 MWh CTES system will be integrated into an existing coal power plant, providing a slipstream of high-temperature steam for testing.

In 2013, researchers developed concrete mixtures for thermal energy storage applications that resisted temperatures up to 600° C. At the time, the temperature represented a 50% increase over operating temperatures of other systems. At that higher temperature, researchers said the unit cost of energy stored in concrete was estimated at $0.88 to $1.00/kW (thermal).

EPRI said that the CTES system it plans to test may enable a coal plant to run more consistently, providing stored heat when electricity is not needed. Such operating cycles better fit a thermal plant’s design and could improve its profitability. The technology also can be applied to natural gas, nuclear or concentrating solar power, EPRI said.

EPRI will lead a team of Bright Generation Holdings, the CTES technology developer; AECOM, to perform engineering, procurement and construction work; and Southern Company, to provide the field test site and operational support. The pilot project was commissioned by the Department of Energy and its National Energy Technology Laboratory. A web search showed that Bright Generation is an Australian-based firm founded in 2009.

The testing will establish the capabilities of the CTES system in a real-world environment, demonstrating its efficiency and ability to handle flexible operating conditions. In addition, an analysis will be done to determine the costs and benefits of a full-scale application of CTES technology.

EPRI said that concrete thermal energy storage has the potential to be "significantly cheaper" than batteries with a smaller footprint. It also has the potential for longer-duration storage, which will be critical as more wind and solar come online.

Initial project work is scheduled to start in October 2019, with construction beginning within a year. The pilot project becomes operational in early 2021.