Techno-economic analysis of an integrated liquid air and thermochemical energy storage system

Abstract

The rapid increase in renewable energy applications has heightened the need for developing efficient and cost-effective energy storage technologies. In this study, a novel integrated liquid air and thermochemical energy storage system is proposed and examined. This integrated storage system is found to be superior in many aspects than both the stand-alone liquid air energy storage and thermochemical energy storage technologies, including high energy storage density, high round-trip efficiency, no geographical limitation, and negligible environmental concern. These are derived from the synergies when integrating those two subsystems. More specifically, the liquid air energy storage subsystem ensures a minimum storage volume of air and a high round-trip efficiency of the integrated system, while the thermochemical energy storage subsystem allows it to have a high energy storage density and high operating temperature without the necessity of burning fossil fuels. To assess the performance of the integrated storage system, thermodynamic and economic analyses are carried out by using Aspen Plus v10. According to the thermodynamic analysis, the round-trip efficiency and the energy storage density of the integrated storage system are found to be 47.4% and 36.8 kWh/m3, respectively. The round-trip efficiency is about 13.3% higher than that of the stand-alone thermochemical energy storage system and the energy storage density is nearly 3.4 times that of the stand-alone liquid air energy storage system. In terms of the economic performance, the integrated system with a plant size of 60 MWe presents a payback period of around 10 years and a levelized cost of electricity of 179–186 USD/MWh over a 30-year period.