This paper proposes a novel compressed air energy storage (CAES) system that fundamentally integrates gravity to achieve constant -pressure operation. By simultaneously storing thermal energy, pressure potential energy, and gravitational potential energy, this innovative system facilitates highly efficient and stable-pressure energy storage and release performance. To thoroughly understand its performance, the study employs a comprehensive methodology combining mathematical modeling, thermodynamic simulations, and theoretical analysis to investigate the underlying energy storage mechanisms and the specific characteristics of energy and exergy storage. Furthermore, a scaled -down experimental prototype of the gravity -enhanced constant-pressure air reservoir was constructed and tested, successfully verifying its dynamic pressure -stabilizing capabilities under realistic operating conditions. Theoretical analysis yields several critical insights into the system's thermodynamic behavior. It reveals that the system's total energy storage is predominantly in the form of compressed thermal energy, whereas exergy storage is primarily driven by pressure potential energy. Gravitational 2 potential energy accounts for less than 1% in both metrics. Despite this, the system demonstrates exceptional thermodynamic performance, achieving a maximum round -trip efficiency of 68.33%. When compared under identical heat storage temperatures, this novel system consistently outperforms traditional constant-volume CAES systems. Moreover, the constant-pressure feature provides a massive advantage in spatial efficiency. For a given power generation capacity, the required air storage volume is drastically reduced compared to traditional constant-volume systems, with the maximum volume reduction reaching an impressive 91.07%. This significant reduction in reservoir size can substantially lower capital costs and alleviate geographical constraints for large-scale energy storage deployment. Experimental results further validate the system' s operational robustness, demonstrating that the gravity -enhanced constant-pressure reservoir can maintain a highly stable pressure output even when subjected to significant fluctuations in inlet and outlet flow rates. However, the study also identifies a practical engineering challenge: real -world applications must carefully account for pressure losses caused by mechanical friction within the gravity -based pressure -regulating mechanism. Additionally, economic analysis indicates that the novel system posses ses promising potential in terms of cost and revenue. In conclusion, the gravity-based CAES system offers a compelling solution to the inherent inefficiencies of traditional systems. By maintaining constant pressure during both the charging and discharging phases, it effectively prevents compressors and expanders from operating under off-design conditions. Therefore, the operating efficiency of the compressors and expanders can be maintained at the designed level, leading to round -trip system efficiency improvement. This not only enhances overall system efficiency but also dramatically reduces the required air storage volume. Ultimately, this research provides a novel, highly promising technical pathway for the widespread commercial adoption and scaling of compressed air energy storage technologies in future renewable energy grids.