Perspectives on Solar Salt-Based Nanofluids Used in Concentrated Solar Power Plants

Concentrated solar power (CWP) technology has matured sufficiently for large-scale implementation. In a typical plant, the solar energy is captured by mirrors and directed onto heat-transfer fluid (HTF), typically a molten salt that is further conveyed to the thermal energy-storage system before being channeled to power turbines, generating electricity. A major concern about this technology is the need to reduce the levelized cost of electricity, necessitating heightened efficiency to enhance cost competitiveness and foster greater market penetration. One approach to achieve this involves replacing the current nitrate-based molten salt mixture with nanofluids. They combine nitrate-based molten salt and small amounts of nanomaterials of different dimensionality. These promising HTFs present a superior performance concerning their physical, thermal, and chemical properties. However, there is a lack of studies related to understanding the effects of nanomaterials and the underlying enhancement theories. Therefore, in this article, a detailed revision of the state of the art in experimental and theoretical studies of nanomaterials in a binary commercial nitrate-based molten salt (solar salt) as HTF for CWP plants is presented, highlighting the challenges related to their application and future research directions.