Liquid metal-molten salt mixtures as energy storage - increasing storage efficiency (SALTME PLUS)

Motivation

The temporary storage of electrical energy is necessary in energy systems dominated by volatile sources in order to balance supply and demand. Intermediate thermal storage in molten salt is one way of ensuring that electricity can later be generated continuously and independently of  fluctuations.

Today, molten nitrate salts are often used for high-temperature applications such as solar-generated heat. The reasons for this are the high volumetric heat capacity, the high boiling point, the high temperature stability and the very low vapor pressure of these salts. Nitrate salts are inexpensive, readily available and neither toxic nor flammable. However, their maximum operating temperature is not too high but conversion efficiency from heat to electricity is typically Carnot-limited. Thus high operating temperatures are  favoured.

To improve the efficiency of molten salts as heat storage media, heat transfer fluids that can cope with elevated temperatures are necessary. Chloride salts appear to be an alternative under these boundary conditions, as they allow higher storage temperatures compared to nitrate salts, are inexpensive, readily available and not flammable. However, their higher corrosive impact on construction materials is a disadvantage. This higher corrosiveness means that the efficient use of chloride salts as a heat storage and heat transfer medium is offset by higher costs for the necessary structural materials.

Project objectives 

The overall aim of the project is to develop methods for active corrosion protection by modifying the chloride salt. First of all, electrochemical cells are to be developed and constructed to investigate the planned approaches on a laboratory scale. The results are then to be validated in long-term static exposure tests.

Project partners

The Project is jointly run by the Chair of Hydrogen and Nuclear Energy of the Technischen Universität Dresden, the Institut für Korrosionsschutz Dresden GmbH and HZDR. The Chair of Hydrogen and Nuclear Energy of the Technischen Universität Dresden is coordinating the project.