Experimental and theoretical investigation on using microwaves for storing electricity in a thermal energy storage medium.

Power to heat to power storage units, also known as Carnot batteries, are nowadays some of the most outstanding solutions for ensuring the response to the electricity demand in an energetic scenario based on non-dispatchable renewable sources like wind or photovoltaic technologies. One of the main challenges of this concept is how to store the electricity as heat in the most efficient way. In this paper the use of microwaves for converting electricity into thermal energy stored in molten salt is proposed. This paper explores the possibility of using microwaves for heating three different materials commonly considered as storage media in CSP applications: NaNO₃, KNO₃ and the solar salt mixture. The study focuses on permittivity measurements since this parameter allows distinguishing whether a material can be heated by microwaves or not. Further studies comparing both microwave and Joule heating methods will be presented in a future work at a later stage. The preliminary results of the feasibility of this CIEMAT's proposal are presented in this paper. [ABSTRACT FROM AUTHOR]