Next-Generation Molten Salt Thermal Energy Storage Based on Chlorides: Stirring Dynamic Corrosion Tests on Commercial Alloys

Abstract

Molten salts can be used in many ways as thermal energy storage media. The use of chloride salts is very promising in this regard, as it reduces investment costs and increases efficiency. However, due to their extremely high corrosiveness, they are not yet used commercially, as this would require special and very expensive alloys. Initial experiments show, however, that with suitable pre-treatment of the salt, corrosion of commercial stainless steels can be significantly reduced. These experiments were all carried out statically. However, since the salt moves in the real operation of a salt based thermal energy storage, this thesis attempts to take this into account through a dynamic experiment. It shows that the corrosion rates increase significantly and the value required by the US government (below 15 µm) cannot be met. Chromium depletion and the associated pitting corrosion are the main causes of this. To minimize the impact of corrosion, Nickel based alloys have to be used which are expensive for commercial scale deployment