Review of commercial thermal energy storage in concentrated solar power plants: Steam vs. molten salts

Thermal energy storage systems are key components of concentrating solar power plants in order to offer energy dispatchability to adapt the electricity power production to the curve demand. This paper presents a review of the current commercial thermal energy storage systems used in solar thermal power plants: steam accumulators and molten salts. It describes the mentioned storage concepts and the results of their economic evaluation. The economic value of the TES system is assessed by the Levelized Cost of Electricity (LCOE) calculation, an economic performance metric commonly used in power generation in order to compare cost of electricity among different power generation sources. Lots of studies have been done in the past to compare the LCOE of a complete solar thermal power plant using thermal energy storage systems. However, no specific studies related to the thermal energy storage levelized cost of electricity itself were done. The objective of this study is focused in the comparison of the TES LCOE where calculations are done for a 100 MW Rankine cycle with different plant configuration and for different storage sizes ranging from 1 to 9 h of equivalent full capacity operation.