Progress in Research and Development of Molten Chloride Technology for Large-Scale Thermal Energy Storage at above 700°C

Kurzfassung

In state-of-the-art commercial concentrating solar power (CSP) plants, thermal energy storage (TES) of nitrate/nitrite molten salts (e.g., Solar Salt NaNO3-KNO3 60-40 wt.%, max. operating temperature of 565°C due to thermal stability limit) is used with a global capacity of >50 GWh [1]. Next-generation CSP plants with higher operating temperatures of ≥700°C need advanced high-temperature TES systems and power cycles (e.g., supercritical CO2 Brayton) for a higher energy conversion efficiency (>50%) and lower levelized cost of electricity (LCOE) [1]-[2]. The next-generation molten salt TES technology based on chlorides is such a promising TES technology [2], since compared to other TES technologies like solid particles, its replacement to the nitrate/nitrite TES in CSP can keep the current CSP system design and the key components (e.g., molten salt pump, salt receiver, etc.) [2]. Besides CSP, molten salt TES has emerging applications in, e.g., industrial processes, conventional power plants and electrical storage (e.g., Carnot battery (CB)) [3]-[5] (see Fig. 1).