Molten Oxide Glass Materials for Thermal Energy Storage

Halotechnics, Inc. is developing an energy storage system utilizing a low melting point molten glass as the heat transfer and thermal storage material. This work is supported under a grant from the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E). Advanced oxide glasses promise a potential breakthrough as a low cost, earth abundant, and stable thermal storage material. The system and new glass material will enable grid scale electricity storage at a fraction of the cost of batteries by integrating the thermal storage with a large heat pump device. Halotechnics is combining its proven expertise in combinatorial chemistry with advanced techniques for handling molten glass to design and build a two-tank thermal energy storage system. This system, operating at a high temperature of 1200 °C and a low temperature of 400 °C, will demonstrate sensible heat thermal energy storage using a uniquely formulated oxide glass. Our molten glass thermal storage material has the potential to significantly reduce thermal storage costs once developed and deployed at commercial scale. Thermal storage at the target temperature can be integrated with existing high temperature gas turbines that significantly increase efficiencies over today's steam turbine technology. This paper describes the development and selection of Halotechnics' molten glass heat transfer fluids with some additional systems considerations.