Additive effect on lithium silicate pellets for thermochemical energy storage

The global increase in energy consumption has caused serious environmental problems, especially CO2 emissions. In general, CO2 is produced from the combustion and oxidation reaction at high temperature. The use of thermochemical energy storage is considered and appropriate approach to enhance the utilization of surplus or waste heat from high temperature industrial processes. So far, there are very few reports that have been published for high temperature thermochemical energy storage. In this study, high temperature thermochemical energy storage based on the lithium orthosilicate/carbon dioxide (Li4SiO4/CO2) reaction was developed. A new candidate storage material was fabricated with four different concentrations of the potassium carbonate (K2CO3) additive (0, 6, 11, 17, and 33 mol %), in the shape of pellets, from the point of energy density view. On the basis of the results of the carbonation and decarbonation experiments, the highest thermal output and storage densities were recorded for a pellet possessing a 11 mol% concentration of the K2CO3 additive. Furthermore, this pellet, LK11, showed cyclic ability with repeat reactions over twenty cycles. Thus, LK11 pellet can be used as a thermochemical energy storage material because of its ability to store and release heat at high temperatures, ranging from 550 to 700°C