Systematic Analysis of Fresnel CSP Plants with Energy Storage

Abstract

The integration of thermal energy storage (TES) in a concentrating solar thermal plant (CSP) is an exclusive feature of this technology, offering it a superior advantage compared to other solar power generation systems, since it allows an efficient integration in the electricity grid and optimised operation flexibility. Within this article various TES configurations are identified and evaluated in combination with corresponding power block set-ups for a linear Fresnel CSP plant. The study scopes plants utilizing Direct Steam Generation (DSG) or Direct Molten Salt solar fields (DMS SF); Indirect Molten Salt (IMS), Direct Molten Salt (DMS TES) and/or Phase Change Materials (PCM) storage systems; and reheat or non reheat power blocks. Two concepts have been identified offering a credibly high techno-economical potential: the DMS concept and a concept combining a DSG solar field with PCM/IMS TES. The analysis of the power block efficiency versus storage specific energy capacity (amount of stored energy per unit of storage medium mass) exhibits a substantial advantage of the DMS concept. Nevertheless for a better understanding of its techno-economical potential, this option demands further evaluations especially with respect to operational costs. Even though in light of this analysis the DSG+PCM solution seems at first less attractive according to the indicators investigated, the potentially lower cost of PCM TES could allow such a concept to be competitive against DMS, provided that storage component investments and operation costs are lower than for the DMS case.