Potential of nanoparticles in solar thermal energy storage

•Solar thermal collectors, heat transfer fluids and thermal storage technologies are presented.•Comparison among TES technologies is conducted.•Types and classification of nano-particles are discussed.•State of the art of using nano-additives to base storage material is reviewed. Solar thermal energy (STE) is characterized by its ability to generate bulk power via integration with thermal energy storage. This feature made STE an attractive option over other renewable energy systems. However, the development of cost-effective storage technologies relates mainlyto the thermal and chemical properties of storage material. This paper reviews the research development of using nano-additives to base storage material. Through reviewed articles, it is found that silica and alumina nanoparticles (NPs) are the most efficient candidate to enhance the specific heat capacity (SHC) of the storage media, by using 1 wt% concentration an average of up to 120 and 60% in heat capacity and thermal conductivity/diffusivity, respectively enhancement can be achieved. The enhanced SHC of nanocomposite showed stability up to 400 – 450 °C, afterword the mixture showed some changes. On the other hand, adding NPs didn’t show a significant change in the melting temperature and the heat of fusion for the nano-mixture compared to the base material. However, significant enhancement occurred in thermal conductivityand thermal diffusivity. Implementing the developed NPs technology in the storage media could increase the energy output and efficiency of the system, and that causes a significant reduction in the levelized cost of electricity (LCOE). However, more studies should be conducted on nano-mixture stability and its life span.