Studies on the thermochemical energy storage in the coal ash zeolite/water system

Abstract

Deterioration of the air quality and the greenhouse effect requires replacement of the conventional fuels with renewable energy sources (RES). The main disadvantage of RES is the intermittent production of energy during the day and the different seasons. This requires efficient energy storage solutions. Affordable technologies applicable to household-scale heating are thermochemical energy storage systems (TES). TES are usually applied for concentration and storage of solar energy. TES based on zeolites as heat storage media use the exothermic effect of water adsorption. The preferred storage medium is commercial zeolite 13X, which is characterized by high porosity and a large specific surface area. In these systems, the charging is carried out at 130-180 °C and the energy storage efficiency is over 90 %. In the present study, storage media of zeolite X synthesized by the alkaline conversion of coal fly ash was studied in a laboratory assembled TES as a possible substitute of zeolite 13X. The results revealed a micro-mesoporous structure for coal fly ash zeolites (CFAZ) in contrast to the microporous 13X. The charge of TES with CFAZ can be carried out at lower temperatures, while its discharge is enough exothermic. The utilization of coal ash as raw materials for synthesis of heat storage media contribute to many environmental benefits.

Study on the Performance of a Solar Heating System with Seasonal and Cascade Thermal-Energy Storage

“…Zeolite 13X has many advantages, such as sufficient heat of adsorption as a hydrophilic material, high thermal-storage density, tolerance to water, no-swelling property, utilization of low-temperature thermal energy, and environmental protection. Therefore, zeolite 13X has been adopted and investigated for many adsorption thermal-storage systems [24][25][26][27].…”