Compressed air energy storage (CAES) system can smooth out the fluctuated power from renewable energy and allow it to meet electricity demands reliably. It further enables the mitigation of renewable energy curtailment. A hybrid energy storage system integrating high‐temperature thermal energy storage (HTTES) and CAES is proposed. In the energy charging process, the high‐ and low‐quality power from renewable energy are stored separately in the air storage reservoir (ASR) and HTTES system. In the energy discharging process, the compressed air is heated to high temperature in the HTTES system and finally expands in air turbines for electricity generation. Thermodynamic analysis reveals that a round trip efficiency of 64.36% with an energy storage density of 5.38 kWh m−3 can be achieved. It is found that the proposed hybrid system has the beneficial effect of improving the system performance. The largest exergy destruction takes place in the HTTES system. The round trip efficiency is mostly sensitive to the output temperature of HTTES, the isentropic efficiency of compressors and turbines, and the maximum and minimum operating pressures of ASR.
Summary
The large‐scale penetration of renewable energy leads to some imperative issues to the power grid. Energy storage technology is regarded as an effective method to solve these problems. In this paper, a hybrid cogeneration energy system based on compressed air energy storage system with high temperature thermal energy storage and supercritical CO2 Brayton cycle is proposed. A thermodynamic model of the system is established. Energy and exergy analysis are carried out based on a case study. It was found that under the design condition, the round trip efficiency of 58.66%, the energy storage density of 5.45 kWh/m3, and the overall exergy efficiency of 62.00% can be achieved. At the same time, the hot water about 88°C can be supplied. The influences of some key parameters on the performance are analyzed. It was found that the round trip efficiency is most sensitive to the outlet temperature of high temperature thermal energy storage system, isentropic efficiency of compressors and turbines, followed by the intercoolers effectiveness.
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