Modelling and performance analysis of a Low Temperature A-CAES system coupled with renewable energy power plants

The ever-increasing electricity production from non-programmable Renewable Energy Sources (RES) requires flexible and sustainable solutions for energy storage. In this paper, the design, and the performance of a Low Temperature Adiabatic Compressed Air Energy Storage (LTA-CAES) system are presented. The design of this system is optimised to better utilise the energy produced by either a photovoltaic (PV) power plant and an onshore wind farm in order to meet the energy demand of a small town of about 10,000 inhabitants, considered as the case study. To ensure efficient operation of the turbomachines, the mass flow rate during both the charge and discharge phases was fixed, allowing most of the compressors and turbines to operate at design conditions. Two packed-bed Thermal Energy Storage (TES) systems are used to store the thermal energy produced during the compression phase: the first exchanges heat directly with the compressed air, while the second uses Therminol-66 as a heat transfer fluid. A mathematical model of the LTA-CAES system was developed using MATLAB/Simulink to simulate its performance, considering the off-design behaviour of the turbomachines and the TES systems over a year. The results demonstrate that the LTA-CAES system increases the share of the yearly energy demand covered by renewable energy, from 41.8% to 60.7% when coupled with the PV plant, and from 48.0% to 56.5% when coupled with the wind farm.