Engineering researchers at the University of Arkansas are developing improved methods of storing thermal energy in concrete.

"Solar holds great promise as an alternative source of energy," said Panneer Selvam, professor of civil engineering and director of the university’s Computational Mechanics Lab. "The problem is that scientists and engineers have not yet developed technology that will allow producers to harness solar power efficiently. So, one area of emphasis to reduce costs is something called thermal energy storage, which is nothing more than developing effective and cost-efficient methods of transferring heat from collectors and holding it before sending it to generators."

To date, energy has been stored in concrete at a maximum operating temperature of 325°C. Because higher temperature storage lowers cost, the researchers are experimenting with storing heat up to an operating temperature of 500 to 600°C.

The researchers are systematically testing the performance of various concrete mixes and investigating better ways of transferring heat from the solar collectors into concrete.

Current technologies used to store solar power cost between 13 and 17 cents per kilowatt hour. The research is part of a US Department of Energy programme aiming to achieve thermal energy storage at 5 cents per kilowatt hour for up to 16 hours by 2020.