Introducing a hybrid mechanical – Chemical energy storage system: Process development and energy/exergy analysis

Abstract

The purpose of this study is to develop and introduce a novel hybrid energy storage system composed of compressed air energy storage cycle as mechanical storage and amine assisted CO2 capture cycle as chemical energy storage. The novelty of this study is to increase the efficiency of mechanical storage cycle by using chemical storage and in this way, the heat released and absorbed by the chemical cycle is used. Two methods of first and second law examination are used to study proposed system. In particular, this energy storage system that stores energy by simultaneously compressing a gas to a higher enthalpy state and recovering the heat of compression by driving a somewhat reversible chemical reaction. The heat energy in the chemical reaction is then recovered while the gas is expanding to a lower enthalpy state. Reboiler of the desorption column requires 1600 kW heat and the power produced by the turbines and consumed by the compressors is 2400 kW and 3884 kW, respectively. Also, the flow rate of the mechanical storage working fluid is 1773 kgmole/h and the storage temperature and pressure are 100 °C and 25 MPa, respectively. In this study, Aspen HYSYS and MATLAB software were used simultaneously for simulation and the results show that round-trip efficiency and exergy efficiency are 51.45% and 72.16%, respectively. Finally, the effect of the various parameters such as fluids inlet temperature to absorption column, CO2 loading and storage temperature on round trip efficiency and exergy efficiency are investigated.