Nicolas Calvet

Central receiver-based concentrated solar power (CSP) systems play a crucial role in solar energy technology, particularly for their ability to operate at higher temperatures than conventional linear concentrators, and for better integration of thermal energy storage in a more direct manner. This paper methodically examines the development and classification of central receiver-based CSP technologies, including power towers, solar furnaces, and beam-down configurations. It aims to emphasize the operational advantages and challenges of these technologies through a literature review. Through an in-depth examination of strategic pathways, including hybridization and co-location, this study reveals critical trends in market deployment frameworks, underpinning the future of CSP integration in the transition to renewable energy solutions.

This review categorizes the thermal energy storage (TES) technologies—sensible heat, latent heat, and thermochemical storage—and evaluates their development, application, and performance within central receiver-based concentrated solar power plants. This study explores the progression of TES systems, delineating the evolution from technologies such as saturated steam and molten salt, first used in the Eurelios power plant in 1980 as a protective storage solution for 30 minutes, to commercial molten salt storage capacities of up to 15 hours. This study also examines emerging research and development technologies aimed at achieving higher efficiencies and operating temperatures. The objective is to identify technological trends, assess the efficacy of different TES systems, and highlight future directions for research and application.

This work proposes a novel concentrating solar power (CSP) plant configuration aiming at a high operation temperature of 1000°C. The thermal energy storage system (TES) would be the focus of this research by modifying it and proposing four configurations to enhance the overall efficiency of high-temperature solar power towers. The objective is to identify the most thermodynamically efficient designs by analyzing the literature on the different components and comparing them to a reference base case of a conventional 100 MWe solar power tower plant (2-tank molten salt TES) operating at 565°C. The proposition consists of a Brayton/Rankine combined cycle with a double cascade TES. In the proposed cascade TES, the primary unit consists of a high-temperature air/ceramic packed-bed thermocline operating at 1000°C, while the secondary unit is a single molten salt tank used as sensible heat. The secondary TES is used as a heat sink during charge, improving efficiency and reducing the size of the air/ceramic-packed bed by extracting the thermocline out of the tank. Excess energy stored in the secondary TES is utilized for preheating during discharge. The methodology incorporates evaluating various combinations of solar block, TES, and power block integration. Combinations are selected from a comprehensive literature review. The study focuses on night-time operations. Further analysis of the cost-benefit of the designs would be required to compare the overall energy production and furthermore the LCOE.

The challenge of imbalances between renewable energy supply and grid demand underscores the significance of energy storage in microgrids. This research presents an empirical assessment of the operational capabilities of a full-scale Electrical Thermal Energy Storage (ETES) prototype system named Thermal Energy Storage Power On Demand (TES.POD®), in solar-abundant and harsh desert conditions. The system incorporates a high-temperature commercial-scale latent heat thermal energy storage, integrated with a Stirling engine. Over a continuous span of 10 days, from September 26th to October 6th, 2022, the input and output power, as well as the heat transfer fluid temperatures during charging and discharging were monitored to assess the power block and system efficiencies. Results from the experiments reveal that this prototype effectively maintains a near-constant electricity production rate of 10.5 ± 1 kW for a discharge duration of 13 hours. Average cycle efficiency stands at 23%, while power block efficiency reaches 25%. These findings collectively suggest the system's potential for applications involving long duration thermal energy storage.