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Acciona Solar, under the Thermal Storage FOA, plans to design and validate a prototype and demonstrate a full-size (800 MWth) thermal energy storage (TES) system based on phase change materials (PCMs).


Acciona's PCM module is designed to be the building block of a TES system that can be deployed at costs in line with the benchmark established by DOE for the year 2020. The goal is to develop a reliable, unsophisticated, modular, and scalable TES system that can be mass-manufactured, utilizing the most advanced automated fabrication and assembly processes and ant that can be installed in the field in the most cost-effective configuration. Achieving this goal would facilitate attainment of LCOE of $0.07/kWh by 2015. It is believed that the DOE targets can be attained by finding the best combination between the size of the TES module, its optimal integration in the power cycle, and the best PCM material for the application.

Acciona is using a test loop to validate its PCM approach to thermal storage.


The use of PCMs in TES allows the storage subsystem to take advantage of latent heat, and thus more energy can be stored in a smaller volume of material. The design employs a flat panel heat exchanger submerged in molten salt with a vibratory mechanism to prevent the solidification of salt on the heat exchanger surface. At the end of this project, Acciona Solar intends to have demonstrated a full-size, 800 MWhth TES system with costs <$15/kWhth with a round-trip efficiency >93%.

Publications, Patents, and Awards

Final Report

Learn about other DOE competitive awards for concentrating solar power research that are in progress.