Local storage of solar energy by reversible reactions with sulfates

Abstract

The problem of the storage of solar energy is of prime importance. Among the possibilities for thermal storage, the use of the heat of a reversible reaction seems to be very attractive because of its high energetic content. In 1961 Goldstein[1] proposed such a method and more recently Wentworth[2] has reviewed many simple stoichiometric decomposition reactions in terms of their reversal temperature. In this paper the authors study the possibilities offered by the decomposition of the sulfates of MgAlFeCoNiCu and Zn in different processes to store solar energy: hot and cold storage with SO 2O 2 or SO 3 are considered. In addition, an exergy ratio is defined in order to classify the various sulfates. Finally as an example, a determination of the amount of the storage medium is presented for the case of NiSO 4; data from the French Solar power plant (THEMIS) which is under construction were used as a basis and these were compared with the weight of the salt necessary to store a given power.