Performance assessment and optimization of concentrated solar power plants with paired metal hydride-based thermochemical energy storage

Abstract

The main objective of this study is to evaluate the innovative future concept of a concentrated solar power (CSP) plant, specifically focusing on a CSP-driven Rankine cycle. Additionally, a suggested energy storage solution for the analyzed CSP plant is the thermochemical energy storage (TCES) approach. The TCES system used paired metal hydrides integrated with phase change material (PCM). A comprehensive mathematical model has been developed to enable performance predictions for the entire CSP plant as well as each of its components. This model considers the thermal coupling between the solar field, the thermochemical storage system, and the power block in order to assess the overall performance of the CSP plant. Utilizing this successfully verified model with reference data, a parametric study is conducted on various operating parameters to identify optimal operating points for the storage system in relation to the overall efficiency of the CSP plant. Furthermore, the critical issue of appropriate and novel concepts for MHs-based TCES integration in CSP plants is discussed in detail. The CSP plant's performance was examined as a function of storage cycle duration, charging and discharging temperatures, melting PCM temperature, and thermal efficiency. Based on the findings, it has been observed that higher charging temperature and integration of PCM into the thermochemical energy storage (TCES) system can lead to a significant reduction of 13-fold in the required solar collector area and a notable increase of 77 % in the efficiency of the CSP plant. Thus, the proposed TCES system appears to be the most promising future heat storage system for CSP plants.