A Review of Thermochemical Energy Storage Systems for Power Grid Support

Abstract

Power systems in the future are expected to be characterized by an increasing penetration of renewable energy sources systems. To achieve the ambitious goals of the “clean energy transition”, energy storage is a key factor, needed in power system design and operation as well as power-to-heat, allowing more flexibility linking the power networks and the heating/cooling demands. Thermochemical systems coupled to power-to-heat are receiving an increasing attention due to their better performance in comparison with sensible and latent heat storage technologies, in particular, in terms of storage time dynamics and energy density. In this work, a comprehensive review of the state of art of theoretical, experimental and numerical studies available in literature on thermochemical thermal energy storage systems and their use in power-to-heat applications is presented with a focus on applications with renewable energy sources. The paper shows that a series of advantages such as additional flexibility, load management, power quality, continuous power supply and a better use of variable renewable energy sources could be crucial elements to increase the commercial profitability of these storage systems. Moreover, specific challenges, i.e., life span and stability of storage material and high cost of power-to-heat/thermochemical systems must be taken in consideration to increase the technology readiness level of this emerging concept of energy systems integration.

Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides

“…Latent heat energy storage is possible when the material undergoes a phase change such as freezing or melting [1,2], whereas phase change materials (PCM) are possible due to absorption or release of energy by the material. Thermal energy storage (TES) that is integrated with concentrated solar power (CSP) [3][4][5][6], can be used when variable energy or electricity demand is high. Thermochemical energy storage (TCES) is an attractive and alternative means of solar storage at higher temperatures (400-1200 °C).…”

“…TCES is advantageous in offering high energy density and a possibility of energy storage at room temperature using solid stable biomolecules. Pertaining to TCES application, there are oxides that were proven to show promising results for their energy storage capacity, such as metallic oxides [5,[7][8][9], hydroxides, particularly calcium hydro oxides [10][11][12][13][14][15][16], and carbonate-made materials including calcium [17][18][19] and strontium carbonate [20,21]. However, these carbonates require structural stabilization to hinder sintering at high reaction temperature.…”

Survey Summary on Salts Hydrates and Composites Used in Thermochemical Sorption Heat Storage: A Review

“…During this exothermic step, the heat is released [34]. An energy storage system can be categorized based on the following features [35][36][37][38]:…”

“…Heat cannot be stored for a long time because SHS and LHS require isolation systems during storage to prevent thermal losses [36]. TCES for hot/cold request, despite its seasonal storage capacity, is still in the primary stages of production, with only a few prototype setups [35].…”

“…TCES technology has fascinated and attracted attention in many domains [43] due to its potentially higher energy storage density, which is five to 10 times higher than LHS and SHS systems, respectively [44]. Because of its high energy density, thermochemical thermal energy storage systems (TCES) are more compact energy systems, and their usage, which decreases the system's volume, may be very efficient in circumstances where space is restricted [35]. In term of capital costs, SHS is less costly than LHS and TCES, according to a simplified economic comparison.…”