Review of Carbonate-Based Systems for Thermochemical Energy Storage for Concentrating Solar Power Applications: State-of-the-Art and Outlook

Abstract

Thermochemical energy storage (TCS) systems are receiving increasing research interest as a potential alternative to molten salts in concentrating solar power (CSP) plants. In this framework, alkaline-earth metal carbonates are very promising candidates since they can rely on wide availability, low cost, high volumetric density (>1 GJ m–3), relatively high operating temperatures (>800 °C), nontoxic and noncorrosive chemical nature, and no occurrence of any side reactions involving the production of undesired byproducts. Therefore, their reversible calcination/carbonation reaction with CO2 can be used to store/release energy in CSP plants. However, in spite of these promising features, the TCS research field is relatively new, and most of it is still limited to the lab-scale. Therefore, great research efforts are needed to bridge the gap from fundamental research to real-scale application and implementation of TCS-CSP systems. This manuscript reviews the state-of-the-art of carbonate-based systems for TCS in CSP plants. In particular, the literature has been analyzed in-depth, paying attention to (i) the materials development, with a focus on the solutions available to improve the durability of the materials (namely, the ability to withstand repeated carbonation/calcination cycles); and (ii) the design of the reactor configuration for both the solar-driven endothermic calcination and the exothermic carbonation reaction, focusing on the optimization of the reactor concept, based on the physicochemical properties and working temperatures of the reagents.

Kinetic Insight into the Effect of Self-Generated CO2 on the Thermal Decomposition of Inorganic Carbonates in an Inert Gas Atmosphere: ZnCO3 and CaCO3

“…The reversible thermal decomposition of inorganic solids has been used for various industrial and technological applications and has significantly contributed to the promotion of civilization in history. These old reaction systems have been attracting significant attention for solving today’s global issues related to energy supply and environmental protection. − For example, such reversible systems, comprising the endothermic thermal decomposition and exothermic solid–gas reactions, are promising for developing environmentally friendly technology for thermochemical energy storage. Solid–gas reactions can be used to absorb unwanted gaseous species to protect the environment, whereas thermal decomposition reproduces the solid absorbent. − Furthermore, the reversible exothermic and endothermic processes construct an energy storage scheme.…”

“…These old reaction systems have been attracting significant attention for solving today’s global issues related to energy supply and environmental protection. − For example, such reversible systems, comprising the endothermic thermal decomposition and exothermic solid–gas reactions, are promising for developing environmentally friendly technology for thermochemical energy storage. Solid–gas reactions can be used to absorb unwanted gaseous species to protect the environment, whereas thermal decomposition reproduces the solid absorbent. − Furthermore, the reversible exothermic and endothermic processes construct an energy storage scheme. A reversible reaction system can also be useful for the storage and release of fuel such as hydrogen. − Therefore, a detailed kinetic understanding of both reaction processes is essential to realize future technologies of energy storage and environmental protection.…”

“…Such reversible reaction systems include the thermal decomposition of metal carbonate and the reaction between metal oxide and CO 2 , as typically seen for the thermal decomposition of CaCO 3 and the reaction between CaO and CO 2 (Ca-looping system). − ,− The kinetics of both forward and reverse processes have been extensively studied for practical applications. − In particular, kinetic study on the thermal decomposition of CaCO 3 has a long history and is one of the most extensively studied systems in this class of reaction. − The reaction is characterized by heterogeneous constraints and the significant effect of atmospheric CO 2 . Thus, the kinetics vary with temperature ( T ), partial pressure of CO 2 ( p (CO 2 )) with reference to the equilibrium CO 2 pressure of the reaction ( P eq ( T )), and the advancement of the reaction characterized by the degree of reaction (α).…”

Investigating the activity of Ca2Fe2O5 additives on the thermochemical energy storage performance of limestone waste

“…In detail, as thermal cycling progresses, limestone particles undergo agglomeration, sintering, and pore closure, resulting in the decrease of their reactive surface area and available active sites, leading to reactivity losses. 17,18 Addressing this issue of reactivity losses is critical for enhancing the thermal cycling performance and overall effectiveness of limestone-based TCES systems. In detail, researchers have explored various strategies, with some focusing on the CaCO 3 /CaO particle size optimization, [19][20][21][22] and others on the introduction of inert additives/dopants, [23][24][25][26] and hydration.…”

DFT Study of the Cooperative Promotion of MgO and ZnO on CaCO3/CaO Thermochemical Heat Storage Performance of CaO

“…The utilization of renewable energy, especially solar energy, is considered to be a feasible way to solve the global warming, ecological degradation, and energy crisis. − Concentrated solar power (CSP) coupled with heat storage systems is regarded as one of the most promising technologies for the large-scale and sustainable utilization of solar energy. , Thermochemical heat storage (TCHS) technologies have been considered as the heat storage system for the next-generation CSP plants because of their wide operating temperature range, high heat storage capacities, and low heat loss. , CaCO 3 /CaO TCHS achieves the effective storage and release of solar energy through the calcium looping (CaL) (i.e., the reversible reactions of CaCO 3 calcination and CaO carbonation), as displayed in eq . With the advantages of convenient coupling with supercritical CO 2 power cycles, low feedstock prices, high heat storage density (about 3178 MJ/t theoretically), and high operating temperatures (over 800 °C), CaCO 3 /CaO TCHS is believed to be one of the most prospective TCHS technologies. , CaCO 3 ( s ) ↔ CaO ( s ) + CO 2 ( g ) 0.25em ΔH 29 8k = 178 0.25em kJ / mol …”