Long-term storage of solar energy in industrial process heat and electricity production: an analysis with reference to mediterranean weather

Abstract

This paper describes how thermal processes, which use the integral over time of solar power, represent the best proposition for the long-term thermal storage of solar energy. Mediterranean weather was recorded for 638 consecutive days, starting on 21 October 1976. The performance of a solar power plant producing heat at a constant temperature level of 325°C was taken as a reference by simulating the operation of the plant under different weather conditions. The size of the storage and the maximum age of the heat required for efficient operation for 70% of the days of a year are obtained with reference to the Mediterranean weather. The analysis is then extended to electrical power generation and integrative as well as total solar electricity systems are analysed. Widespread use of solar power plants to produce electricity as integrative or autonomous generators can be accomplished with various efficiencies. With the present state of knowledge concerning the storage and transmission methods of electricity, the best performances are obtained when dynamic storage is used and direct storage is avoided.