Lifetime modeling for a supercritical CO2-molten salt CSP power block

Abstract

To achieve higher efficiency in the next generation of concentrating solar power (CSP) plants, higher temperatures are needed, which will challenge the materials. One scenario would include molten chloride salts for thermal storage and supercritical CO2 (sCO2) for the power block and operating temperatures above 700°C to achieve at least 50% efficiency. For the high pressure (20-30MPa) sCO2 conditions, high strength Ni-based alloys will be required above 700°C and an extensive experimental project has confirmed good sCO2 compatibility for alloys 625, 740H and 282. The data set generated enables more accurate lifetime predictions for 30-year service. Compatibility testing with K-Mg-Na chloride salts has just begun. Initial isothermal capsule results indicate there are promising combinations of salt chemistry, temperature and alloy composition. However, flowing salt testing is needed to evaluate compatibility, which is in progress.