The US Department of Energy (DOE) has released funding to the Argonne National Laboratory for a scaled-up round of independent testing of Terrafore Technologies’ innovative encapsulated thermal energy storage in phase change salts, designed to operate in temperatures to greater than 800°C in a single tank that acts as both storage and heat exchanger.
Argonne scientists approached CEO Anoop Mathur to submit an application when they heard of the potential awards under the SBV program.
“Earlier, at Southwest Research Institute we proved the reliability of capsules with salt melting at 370°C. Argonne tests will be showing the reliability of our capsules; that the special coating on these salt capsules will be able to withstand those temperatures and high pressure, using a test rig at the lab,” said Mathur.
“The capsules for high temperature are ready-to-scale and we expect the thermal storage using these will enable distributed scale CSP like mini-towers and dish collectors as well as next-generation CSP using Supercritical CO2,” he added.
The funding is one of 38 awards that had been funded by the outgoing Obama administration to support startup innovation through the “valley of death” phase of advanced innovative technologies. The results are expected by mid 2018.
Mathur designed the encapsulated salt capsules – what he now calls TerraCaps – to eliminate the need for the two tanks used in today’s sensible heat thermal energy storage systems, the hot and the cold tank. The idea is to be able to store 50% more energy per unit volume than the two tank molten salt thermal storage system used in current CSP projects.
The key to being able to heat and cool in a single tank operation is a space inside each marble-like capsule for salt to expand when it melts.
Mathur pointed out that some of the salts expand as much as 25%. Also, since salts have low thermal conductivity, they are not efficient at transferring heat and require a large heat transfer area; so encapsulating the salts in small capsules results in a large specific surface area that helps maintain the high heat transfer rate needed for power generation.