Effectiveness of the use of nanofluids in concentrated solar power plants – Electrical and environmental assessment

Abstract

Nanofluids are reported in the literature as advanced heat transfer fluids that improve significantly the thermo-physical properties of base fluids and, thus, enhance the performance of the solar systems. However, despite their great potential to improve the thermal and rheological properties when combined with a base fluid, it has been proven in this paper that they have a major limit that makes their integration in commercial scale CSP plants questionable. Indeed, based on various numerical simulations of three different nanofluids (MgO-VP1, Al2O3-VP1, Fe2O3-VP1), the results have revealed that when the base fluid (Therminol VP1) is doped with a certain volume fraction of nanoparticles, its circulation through the CSP’s canalization becomes more energy-intensive. Accordingly, the pumps’ electrical energy consumption increased proportionally with the nanoparticles’ concentration ratio. Consequently, when the nanofluids are used, the net energy production of the studied CSP plant (Noor I, Morocco) decreases compared to the reference case when the base fluid is used. From an environmental point of view, the use of nanofluids in CSP plants aggravates the negative environmental impact by increasing the GHG emissions related to the pumps’ operating process during the life cycle of the CSP plant. Thus, this article has a dual interest; on the one hand, it confirms the benefits of nanofluids on a thermo-physical level and, on the other hand, it highlights their major limitation from an energetic and environmental point of view, when used in CSP plants.