SBIR Phase II: Advanced Thermal Battery Systems for Grid-Scale Energy Storage: Further Optimization of an Innovative Thermal Cycle Test Rig for Large-Scale Deployment

The broader/commercial impact of this SBIR Phase II project is to demonstrate the durability of key subsystems of a novel long duration energy storage technology, which has the potential to increase the capacity of the electric grid. Long-duration energy storage is a key unlock for energy security to provide firm capacity by balancing supply and demand across various timescales. The Total Addressable market (TAM) for grid-scale energy storage is immense and rapidly expanding. Wood Mackenzie forecasts that the global energy storage market will grow 27-fold between 2022 and 2032, reaching a total of 1,420 gigawatt-hour (GWh) of cumulative capacity. This growth represents a $380 billion investment opportunity over the next decade. In the United States alone, the National Renewable Energy Laboratory's Storage Futures Study suggests that economic potential for energy storage could exceed 160 gigawatt (GW) by 2050 in a high renewable energy scenario. The technology's ability to provide long-duration storage (10+ hours) at an estimated capital expenditure (CapEx) of $25/kilowatt-hour(electric) (kWh-e) (class 4 estimate), positions it to play a pivotal role in enabling high renewable penetration and grid decarbonization. The intellectual merit of this project aims to demonstrate the reliability and durability of high-temperature graphite plumbing systems for liquid tin heat transfer. The proposed work will involve extensive accelerated life testing of critical components, including fittings, seals, and pumps, at temperatures up to 2400° Celsius (C) and pressures up to 100 pound force per square inch (psi). This project will validate the long-term viability of the technology for grid-scale applications by subjecting critical graphite components to rapid thermal cycles and prolonged hightemperature operation. Graphite's chemical inertness with liquid tin, high strength, and machinability make it ideal for closed-loop heat transfer systems above 2000°C, but its behavior under sustained thermal cycling and liquid metal flow at this scale is not wellcharacterized. The research will generate data on thermal expansion, oxidation, and structural integrity. Completion of these efforts will lead to a more thorough understanding about graphite behavior and liquid metal handling at extreme temperatures, which will benefit fields such as nuclear energy, aerospace, and advanced manufacturing. Once successful, the project will accelerate the commercial deployment of the technology, as well as enable a new class of high-temperature industrial processes and thermal management solutions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.