Simulation analysis of thermal storage for concentrating solar power

The aim of this study was to evaluate the capacity and analyze the performance of thermal storage required for solar thermal electric power plants in order to increase their capability to supply base load power with less need for back up from fossil fuels. For this purpose, a mathematical-statistical model of hybrid solar-fossil power cycles was developed, which is based on energy balance equations and historical hourly data of direct normal irradiance and load profiles available in the literature. As follows from the computations performed for base load operations, an extremely large storage capacity equivalent to near a thousand full load operating hours should be available to a power plant to achieve continuous electricity production entirely on solar energy (solar fraction equal 1.0) during an annual operating cycle. For state of the art thermal storage technologies having a potential capacity of 10–14 full load operating hours for large-scale parabolic through solar power plants, the assessed solar fraction was 0.4–0.5 respectively, with relation to the specific conditions of calculations. The performance characteristics of thermal storage presented in the paper cover the whole extent of solar fractions from 0.2 (no storage applied) to 1.0 (pure solar operation of a power plant).

► Thermal storage increases sustainability of solar thermal electricity technology.
► Capability of state of the art storage systems is within 14 full load hours.
► Solar fraction of parabolic trough plants comprising thermal storage can reach 60%.