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$3 Million to Demonstrate High-Temp Solar Energy Storage

September 16, 2015 by Jeff Shepard

Southern Research has signed a jointly funded cooperative agreement with the U.S. Department of Energy. This work is under the SunShot Initiative as part of the Concentrating Solar Power: Advanced Projects Offering Low LCOE Opportunities (CSP: APOLLO) funding program. The three-year project will support the scale-up and demonstration of an innovative thermochemical energy storage system (TCES) that will allow concentrating solar power (CSP) facilities to operate around the clock.

This project builds on developments from a previously funded SunShot Initiative award that led to Southern Research's successful development of a low-cost calcium-based sorbent which reacts with carbon dioxide (CO2) to store thermal energy. In addition to low cost, long-term durability and high capacity for CO2 are key requirements that have been demonstrated for the sorbent.

The new CSP: APOLLO project will demonstrate this energy storage technology at a 1 MWhrth scale under real-world conditions at Southern Research's Southeastern Solar Research Center. Partners Southern Company and the Electric Power Research Institute (EPRI) will support the evaluation of the technology to better understand its potential impacts on the cost of renewable electricity.

"Utilizing these low-cost, regenerative, calcium-based sorbents, which were previously researched for CO2 capture in coal-based power generation facilities, leverages existing knowledge for a novel application," said Southern Research's Santosh Gangwal, Ph.D., project principal investigator. "Through rigorous material development and testing, we are refining these sorbents to perform successfully throughout the entire 30-year life of a CSP plant."

The new system stores energy when sunlight is plentiful and then releases energy after sundown. This enables the CSP plant to produce electricity in a stable and consistent fashion, and also to operate at significantly higher capacity factors, leading to a lower overall cost of producing electricity. Furthermore, the production of electricity can be shifted to occur whenever power demand peaks, making the electricity much more valuable and less dependent on the sun.

Southern Research's TCES system is projected to cost about one-quarter as much as current state-of-the-art molten salt storage systems and will be able to store the same amount of energy in a system about one-sixth the size. The Southern Research TCES system can also operate sustainably up to 750 degrees Celsius – about 200 degrees Celsius higher than current systems.

"As the next generation of CSP plants move toward new, higher temperature, more efficient, supercritical CO2 cycle, a new generation of cost–effective, high-temperature, energy storage systems needs to be developed," said Southern Research's Tim Hansen, project co-principal investigator. "Our energy storage system will enable these technologies and lead to competitive large-scale renewable power generation."

"Southern Research is excited and honored to be selected by the SunShot Initiative for this project," said Bill Grieco, Ph.D., vice president of Energy and Environment, Southern Research. "We are proud to be recognized for our leadership in alternative energy and look forward to the demonstration of our innovative thermochemical storage system at our Southeastern Solar Research Center, where we test and validate technologies for grid-tied solar power generation."