Experimental Analysis and Cost Assessment of a Novel Variable-Volume Air Storage Device Designed for Compressed Air Energy Storage

Abstract

Compressed air energy storage (CAES) has recently gained significant attention as an environmentally friendly, large-scale physical energy storage system. However, its widespread application has been limited due to the high cost of a ground-level air storage device. The previous work by the authors’ team proposed a novel variable-volume air storage (VVAS) device based on working fluid phase change, effectively increasing the air storage capacity. Nevertheless, the early study only focused on thermodynamic performance analysis. Therefore, this study extended the previous work by constructing a corresponding experimental platform for the VVAS device to test its feasibility and developed a cost assessment model to analyze its economic performance. The results demonstrate that the VVAS device allows the air in the storage tank to continue near-isobaric release under the displacement of gaseous R134a at the other side of the bladder when the air pressure in the storage tank decreases to equal the air pressure at the throttle valve outlet. The effective air storage density of the VVAS device can be increased by over 50% under the different air storage pressures. Furthermore, the cost analysis indicates that the unit air storage cost for the VVAS device is 50.20 $/kg, which is significantly lower than the conventional device (80.34 $/kg). These findings suggest that integrating the VVAS device into CAES systems offers a significant advantage for air storage.

Keywords: Compressed air energy storage, Variable-volume air storage, Isobaric, Working fluid phase change, Experimental analysis, Cost assessment