Oak Ridge Scientists Develop Method for Reducing Molten Salt’s Corrosive Effect

The diagram demonstrates how a concentrating solar thermal plant could use molten salts to store solar energy that could later be used to generate electricity. Image courtesy of Jaimee Janiga/ORNL, U.S. Department of Energy.

Scientists at Oak Ridge National Laboratory (ORNL) (Oak Ridge, Tennessee, USA), a research lab managed by UT-Battelle for the U.S. Department of Energy, recently demonstrated a low-temperature, safe route for purifying molten chloride salts that minimizes their ability to corrode metals. This method could make the salts useful for storing energy generated from the heat of the sun. 

As detailed in Frontiers of Chemical Engineering, the experiment involved using thionyl chloride to remove corrosion-causing impurities from the salts. Without this purification, the salts corrode pipes and storage tanks. 

The team melted a commercial carnallite—an abundant mineral being considered for solar-thermal energy storage—and put it into contact with inert gas saturated with thionyl chloride to cause a reaction. The scientists monitored reaction conditions by measuring salt temperature and by analyzing the off-gas thorough infrared spectroscopy. 

“Using high-temperature molten salts to store energy as heat could be key in making solar energy a consistent source of electricity, replacing fossil fuels,” says ORNL’s Joanna McFarlane, who led the team that performed the experiment. 

Aside from McFarlane, who is the interim group leader of ORNL’s Fuel Cycle Technology Group, the ORNL research team includes the following: Guillermo D. Del Cul, distinguished research staff; Jordan R. Massengale of the Fusion and Fission Energy and Science Directorate; Richard T. Mayes, senior R&D staff member; Kevin R. Robb, group leader of the Energy Systems Development Group; and Dino Sulejmanovic, a research and development chemist. 

Source: Oak Ridge National Laboratory, www.ornl.gov