A Discussion of Possible Approaches to the Integration of Thermochemical Storage Systems in Concentrating Solar Power Plants

Abstract

One of the most interesting perspectives for the development of concentrated solar power (CSP) is the storage of solar energy on a seasonal basis, intending to exploit the summer solar radiation in excess and use it in the winter months, thus stabilizing the yearly production and increasing the capacity factor of the plant. By using materials subject to reversible chemical reactions, and thus storing the thermal energy in the form of chemical energy, thermochemical storage systems can potentially serve to this purpose. The present work focuses on the identification of possible integration solutions between CSP plants and thermochemical systems for long-term energy storage, particularly for high-temperature systems such as central receiver plants. The analysis is restricted to storage systems potentially compatible with temperatures ranging from 700 to 1000 °C and using gases as heat transfer fluids. On the basis of the solar plant specifications, suitable reactive systems are identified and the process interfaces for the integration of solar plant/storage system/power block are discussed. The main operating conditions of the storage unit are defined for each considered case through process simulation.

Development of Thermochemical Heat Storage Based on CaO/CaCO3 Cycles: A Review

“…The content related to the reaction conditions will be discussed in detail in the next section. Recently, scholars have conducted lots of research on CaO/CaCO 3 heat storage, continuously optimizing the integrated process of CaO/CaCO 3 heat storage and CSP power generation to improve efficiency [59,60]. Furthermore, reducing the deactivation of CaO during heat storage and improving the heat storage stability have been widely studied.…”

Calcium Looping for Thermochemical Storage: Assessment of Intrinsic Reaction Rate and Estimate of Kinetic/Transport Parameters for Synthetic CaO/Mayenite Particles from TGA Data

“…A generalized scheme showing the way thermochemical energy storage systems may be coupled to CSP plants is shown in Figure . A more detailed discussion of such integration is reported in Lanchi et al…”

“…A generalized scheme showing the way thermochemical energy storage systems may be coupled to CSP plants is shown in Figure 1. A more detailed discussion of such integration is reported in Lanchi et al 12 Among several chemical looping alternatives (hydrides, metal oxides, and carbonate salts 13,14 ), the calcium looping (CaL) process has attracted great interest as a promising system for TCES since it displays several advantages such as low cost, nontoxicity, high reaction temperature for the exothermic reaction (650−850 °C), low hysteresis, and high energy density 11 (∼692 kWh m 3 ). The CaL process is based on the reversible calcination of CaCO 3 into CaO…”

MgCr2O4-Modified CuO/Cu2O for High-Temperature Thermochemical Energy Storage with High Redox Activity and Sintering Resistance

“…Thermochemical energy storage (TCES), which allows higher operating temperature and higher storage density than the current commercial molten-salt storage systems, should be more suitable for the next-generation CSP plants to improve the thermodynamic efficiency of power generation . The metal-oxide redox system is the most potential candidate for TCES based on solid–gas reversible reactions because of its better compatibility with CSP. , Co 3 O 4 /CoO, Mn 2 O 3 /Mn 3 O 4 , and CuO/Cu 2 O have been favored by researchers. ,− The Co 3 O 4 /CoO redox couple has high enthalpy and excellent cycle stability in pure metal oxides, but Co is a scarce mineral resource and toxic. ,− The Mn 2 O 3 /Mn 3 O 4 system has poor reversibility, but its re-oxidation reaction kinetics and cycle stability can be effectively improved by doping with other elements (such as Si, Mg, Fe, etc. ). − However, its energy storage density is lower and a large hysteresis interval between oxidation and reduction leads to adverse effects on the exergetic efficiency of the energy storage process .…”