Abstract Compressed air energy storage (CAES) is one of the effective technologies for addressing the intermittency and variability of solar and wind power. However, the relative narrow power range of conventional CAES hinder efficient integration and stable operation. To address this, a novel Multi-Temperature Graded Compressed Air Energy Storage (MTG-CAES) system is proposed, aiming to broaden the power input /output range, improve energy utilization efficiency, and enhance renewable energy accommodation capability. During charging, the system absorbs wind and solar photovoltaics power by a two-stage adiabatic compressor and a single-stage isothermal compressor, and compression heat are recovered. Meanwhile, wind power with high-frequency fluctuations that is difficult to absorb is converted into heat through resistive heating and stored in the thermal storage system. During discharging, a three-gradient energy release strategy employs the integration of solar thermal energy, compression heat, and surplus wind-generated heat. This enables graded air heating at the expander inlet and tiered power regulation. The results show that the output power range can be extended to 279.17 MW to 682.36 MW and the input power range can be extended to 210.44 MW to 511.32MW. The system maintains high efficiency across different temperature gradient design conditions, with exergy efficiency and round-trip efficiency reaching 70.47%, and 72.34%, respectively. Increasing the adiabatic compressor pressure ratio improves efficiency but narrows the power range. Higher solar temperatures significantly widen the power range, offering advantages in regions with abundant solar resources. A smaller discharge-to-charge time ratio can also widen the power range. The MTG-CAES system offers new options for the depth and use of renewables.
Li et al. (Mon,) studied this question.
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