Status on thermal energy storage with molten nitrate salt above 600 °C

Abstract

Molten nitrate salts are state-of-the-art heat transfer fluids (HTF) and thermal energy storage (TES) in Concentrating Solar Power (CSP) plants. Only recently, the authors of this work demonstrated that higher operating temperatures of at least 620°C can be realized, compared to state-of-the-art temperatures of 565 °C. The development principally enables the transformation of conventional power plants (e.g. coal) into Storage Power Plants that can absorb peak currents from fluctuating renewable sources. The presentation outlines the potential of nitrate salts in these new fields of application with a particular view on the material research level. In the last years the scientific community has made important progress in understanding the fundamental reaction mechanisms in nitrate salts at temperatures above 600 °C (Some accepted reaction schemes from different literature sources are presented in Figure 1). Yet, the schematic description is far from complete and in the presentation we will outline the recent progress and timeline required for the successful implementation of Molten Salt storage above 600 °C.