Thermal Energy Storage for Concentrating Solar Power Plants

Abstract

Thermal energy storage for concentrating solar thermal power (CSP) plants can help in overcoming the intermittency of the solar resource and also reduce the levelized cost of energy (LCOE) by utilizing the power block for extended periods of time. In general, heat can be stored in the form of sensible heat, latent heat, and thermochemical reactions. This article describes the development of a costeffective latent heat storage TES at the University of South Florida (USF). Latent heat storage systems have higher energy density compared to sensible heat storage systems. However, most phase change materials (PCMs) have low thermal conductivity that leads to slow charging and discharging rates. The effective thermal conductivity of PCMs can be improved by forming small macrocapsules of PCM and enhancing convective heat transfer by submerging them in a liquid. A novel encapsulation procedure for high-temperature PCMs that can be used for thermal energy storage (TES) systems in CSP plants is being developed at USF. When incorporated in a TES system, these PCMs can reduce the system costs to much lower rates than currently used systems. Economical encapsulation is achieved by using a novel electroless deposition technique. Preliminary results are presented and the factors that are being considered for process optimization are discussed.

Thermochemical energy storage of concentrated solar power by integration of the calcium looping process and a CO2 power cycle

“…In recent years, a number of thermal storage technologies for medium to high temperature CSP systems have been developed from the use of materials in which energy is stored as sensible heat [1][2][3]. Diverse materials with high heat capacity are employed in thermal energy storage (TES) systems such as water [4], molten salts [5][6][7], mineral oils [8] or ceramic materials [9]. Commercial plants of considerable size (>100 MWt) do already exist where heat is stored in molten salts and used overnight to generate electricity.…”

Metal Nanoparticle–Carbon Matrix Composites with Tunable Melting Temperature as Phase-Change Materials for Thermal Energy Storage

“…6,11,16 Higher temperature PCMs (>200 °C) continue to be a significant area of research due to their application in concentrated solar power plants. 4 High phase transition temperature materials could also be used with other heat sources capable of producing pressurized steam for a Rankine cycle. For common triple pressure power plants, such as natural gas combined cycle and coal, PCM transition temperatures of about 330 °C would be required for evaporation of the high-pressure steam.…”

CuSO4/[Cu(NH3)4]SO4-Composite Thermochemical Energy Storage Materials

“…The two main drawbacks associated with this concept are the necessary heavy thermal insulation, preventing heat losses during storage through radiation, as well as the large volumes of storage medium. Latent heat storage [ 12 , 13 , 14 ]: Heat is stored taking advantage of the energy demand/energy release, associated with a phase-transfer from solid to liquid, or vice-versa. Although the first commercial applications with latent heat storage are already available, the technological readiness is less than for sensible technologies.…”