Thermochemical energy storage in CaCl2-NH3 pair evaluated by rapid multiple adsorption-desorption cycles controlled with wasted iron induction heating

Abstract

Energy storing systems can provide leverage to the current supply demand intermittency issue thus increasing energy efficiency. Among many available technologies, thermochemical energy storage is highly promising. In this work, we investigate, experimentally, for the first time, inductive heating as an approach to direct coupling of power systems with thermal energy technologies. This system also allows for versatile measurements in rapid multiple adsorption–desorption cycle control. Adsorption and desorption cycling of the CaCl2-NH3 adducts is realized in a custom-made setup. Iron wires and waste red mud are investigated as potential inductive materials. Material performance is evaluated after 1, 2 and 1000 cycles using differential scanning calorimetry, thermogravimetry, scanning electron microscopy and specific surface area. Waste red mud shows good inductive potential. No material degradation is observed after 1000 cycles in all cases. Samples heated using waste red mud have a higher maximum absorption capacity (0.304 versus 0.154 gNH3/gCaCl2) and desorption enthalpy (716 versus 460 KJ/ kgCaCl2) compared to the ones heated using iron wires. This is found to be related to the average specific surface area of samples containing red mud, which is almost double that of iron ones. We hope the concept presented here can stimulate research in the direction of inductive heating while simultaneously generating new utilization pathways for waste red mud.