Development and Testing of a Thermal Battery Utilizing Concrete and Thermosiphons for Power Plant Flexibilization

A fast increase in power generation from renewable sources is creating the need for a larger contribution from power generation from other sources. This demands more flexible power generation systems, making energy storage a necessity to integrate flexible power generation with the grid demand. Thermal energy storage is a good option to be integrated with Rankine power cycles. Particularly, sensible heat stored in concrete offers the option for integration with power plants in a flexible and cost competitive way. This paper reports research results performed by Lehigh University for the development of a thermal battery cell (TBC) capable of operating at temperatures up to 450°C. The Lehigh TBC integrates a concrete matrix, engineered to provide enhanced thermal and mechanical properties, and thermosiphon elements capable of dual action operation, engineered to enable charging and discharging on a single thermal battery unit. Components for the TBC were researched in the laboratory, and an integrated single-thermosiphon, 10 kWh th TBC was designed and tested. Efficient heat transfer to/from the storage media, was demonstrated in the lab. The 10 kWh th TBC was tested under several different charging and discharging conditions and proven to be resourceful. Test results demonstrate the feasibility of the concept to store sensible thermal energy in concrete between 300°C and 400°C, with fast charging and discharging performance provided by the thermosiphon, suited for fast ramping of the power generation unit. The Lehigh University team is working on the design, construction and testing of a scale-up 100-kWh