In a parabolic trough collector demo plant run by the German Aerospace Center (DLR) in Évora, Portugal, molten salt is used as a heat-transfer fluid instead of thermal oil. The advantage of molten salt is its stability at higher temperatures. Whereas thermal oil cracks at above 400 °C, molten nitrate salts, such as so-called "solar salt" remain stable until 565 °C, according to a press release sent out by the DLR on 25 October 2021.
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