Abstract
Concentrated Solar Power (CSP) plants provide the twin advantages of energy generation and thermal energy storage. The latter provides CSPs the advantage of persistent power, a feature that is absent in photovoltaic plants. However, there is much to be done to make CSPs competitive with traditional coal-powered plants. Reduction of CSP costs relies on the selection and use of salts with high heat capacity, relatively low melting temperatures and good thermal stability. Chloride salts are viable candidates that fulfill the technical requirements and are relatively low-cost. However, the corrosivity of these salts needs to be addressed. This paper outlines the approach taken to select a promising salt (KCl - 44.5 wt% NaCl), and containment materials (UNS S31600 and UNS N08330 with G10180 as the control/baseline). An experimental approach involving electrochemical testing of candidate alloys (as-received and surface modified) is described. Microstructural characterization included scanning electron microscopy. The selected salt was determined to be a viable candidate as a thermal energy storage medium based on thermodynamic considerations. The containment materials that are compatible with this salt in an argon atmosphere at 700°C are the as-received UNS S31600 and UNS N08330.
