Southern Research Institute has signed a jointly funded cooperative agreement with the U.S. Department of Energy (DOE) as part of the DOE’s new Concentrating Solar Power: Efficiently Leveraging Equilibrium Mechanisms for Engineering New Thermochemical Storage (CSP: ELEMENTS) funding program. The program is part of the SunShot Initiative. CSP: ELEMENTS supports the development of high-temperature thermochemical energy storage (TCES) systems that enable concentrating solar power plants to produce electricity in the evenings and even overnight when the sun is no longer shining.
“Southern Research Institute is excited and honored to be selected by DOE for this project,” said Michael D. Johns, vice president engineering at Southern Research Institute. “We are proud to be recognized for our leadership in alternative energy, and the development of this innovative thermochemical storage system is in great alignment with the work at our recently established Southeast Solar Research Center, where we design, test, and validate technologies throughout the solar energy spectrum.”
CSP technology employs mirrors that concentrate reflected sunlight onto receivers containing heat transfer fluids. From there, the fluids are used to heat water, which in turn generates steam that is used to power turbines and produce electricity. By adding thermal storage to these facilities they are able to operate at significantly higher capacity factors and produce approximately double the energy for the same size power facility. In addition, the production of electricity can be shifted to occur at the same time as peak power demand, making the electricity much more valuable.
More specifically, the Southern Research Institute project will develop a TCES system that uses a low-cost calcium-based sorbent in a reversible closed-loop endothermic-exothermic chemical reaction cycle. The system stores energy during mid-day when sunlight is plentiful in the endothermic step, and then releases energy when the sun is no longer shining during the exothermic step, allowing for electricity to be produced in a more stable and consistent fashion. This TCES system is projected to cost less than a 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.
“Utilizing these low-cost regenerative calcium-based sorbents, researched for carbon dioxide capture in coal-based power generation facilities, leverages existing knowledge bases and is an innovative transfer of technology,” said Dr. Santosh Gangwal, project Principal Investigator. “Through rigorous material development we can refine these sorbents to perform successfully in this environment throughout the entire 30 year life of a CSP plant.”
While molten salt storage systems can only operate up to about 550 degrees Celsius, the Southern Research Institute TCES system can operate sustainably up to 900 degrees. “As the next generation of CSP plants moves towards higher operating temperatures to achieve higher conversion efficiencies, a new generation of high-temperature storage needs to be developed to allow these facilities to continue to provide power in a cost-effective and dispatchable manner,” added Ryan Melsert, co-Principal Investigator of the project.