High-temperature latent thermal storage system for solar power: Materials, concepts, and challenges

Limited reserves of fossil fuels, increased world energy demand and swelling of environment pollution drive a transition towards renewable energy resources which can deliver 3E objectives (Economic, environmental and energy security). However, the inherent intermittency necessitates efficient energy storage systems to harness the true potential of renewable resources. In this context, high-temperature latent heat storage (LHS) using phase change medium (PCM) can be a promising alternative to address the challenges of the variable renewable energy generation with respect to time and space. Currently, central receiver-based 3rd Gen concentrated solar thermal (CST) plant operating at high-temperatures (800-1000 degrees C) is the most attractive technology to convert solar energy to heat. Moreover, advanced power-generating cycles such as supercritical CO2 (sCO(2)) Brayton cycle operating at high-temperature can reduce the Levelized cost of Energy (LCoE) by achieving higher cycle efficiency. Hence, coupling a high-temperature LHS between the central receiver system and sCO(2) cycle can have dual benefits: increase in dispatchability of energy and reduction in LCoE. Furthermore, high-temperature LHS can be devised to store high-grade energy such as spillage of energy from Photovoltaic (PV), wind power plant, and waste heat from energy-intensive industries (e.g. glass melting furnace). This article reports a holistic approach to review different components and design aspects of high-temperature LHS with techno-economic challenges to be overcome. A preliminary numerical study has been performed to predict the melting behavior of high-temperature silicon using COMSOL Multiphysics. Based on the review, two configurations of high-temperature LHS have been illustrated to produce continuous and cost-effective electricity. The first layout is high-temperature LHS coupled with 3rd generation (Gen) CST and the second one is a standalone high-temperature LHS device with Thermionic-photovoltaic (TIPV) diode.