Design and development of a next generation thermal rock bed storage experimental facility

Abstract

The value of concentrating solar power plants lies in dispatchability, which is provided through an integrated cost-effective thermal energy storage system. A thermal energy storage system consisting of a rock bed has the potential to reduce storage capital costs significantly, compared to current state of the art molten salt thermal energy storage systems. The Stellenbosch second-generation rock bed design, for significant cost reduction, has previously been developed and built at Stellenbosch University. This project focuses on improving the performance of the second-generation rock bed thermal energy storage system, through partial re-design, predominantly aiming at maximizing the usable rock mass. The experimental results are used to validate an analytical model which simulates the rock bed thermal energy storage system. Initial findings give a maximum thermal efficiency of 92.40 % and volumetric efficiency of 61.8 %. These results suggest that thermal rock bed storage is a promising technology for cost-effective thermal energy storage in the future.