Scientists at the U.S. Department of Energy’s Oak Ridge National Laboratory have begun operating a unique system designed to enable a variety of testing to characterize the performance of an advanced heat transfer fluid for renewable energy.
Known as the Facility to Alleviate Salt Technology Risks, or FASTR, the system’s inaugural run evaluated the viability of using a mixture of magnesium, potassium and sodium chloride-based molten salt technology for solar thermal power.
FASTR is the first loop of its kind in operation, designed to study potentially corrosive chloride salts in a flowing environment. Proof of stable operation and overall performance could increase the efficiency and economic competitiveness of the next generation of concentrating solar power, or Gen3 CSP. Chloride salt is also a uniquely inexpensive heat transfer fluid that could be directly used for thermal energy storage.
Power tower CSP plants collect and store energy using fields of mirrors that concentrate sunlight onto a receiver at the top of a tower, delivering energy to a heat transfer fluid. These power towers have traditionally used steam or nitrate salts to transfer energy and drive power cycles for electricity generation.
ORNL scientists are using FASTR — which officially started flowing operations in December 2022 — to study the feasibility of a new approach of molten chloride salts as a high-temperature energy storage and heat-transfer fluid. The facility uses a blend of sodium chloride, potassium chloride and magnesium chloride, a cost-effective mixture with a low melting point and favorable thermophysical properties.
“The salt test loop will enable the research necessary to make this technology a reality,” said Kevin Robb, Energy Systems Development group leader in ORNL’s Nuclear Energy and Fuel Cycle Division. “FASTR’s inauguration caps an almost five-year effort that included designing, building and operating the largest open-science research facility pumping molten chloride salt in the United States, and likely the world,” Robb said.