3E analysis and multi-objective optimization of a novel isobaric compressed air energy storage system with a gravity-enhanced air storage reservoir
Ruifeng Cao, Zhe Wang, Hongliang Fan, Ziqi Chen
Abstract
The advanced adiabatic compressed air energy storage (AA-CAES) system is a viable alternative for long term energy storage. The exergy loss during throttling is a major obstacle to performance improvement in AA-CAES system. This paper introduces a new gravity-assisted isobaric AA-CAES system. The air storage reservoir in proposed system consists of three parts: an abandoned vertical mineshaft, a heavy load, and an elastic airbag. By balancing the supporting force generated by the high-pressure air with the gravity of the heavy load, isobaric air charging and discharging process is achieved. Thermodynamic and economic models are developed. The results show that under the optimized design condition, the air and occupied space energy storage density are 2.68 kWh/m 3 and 2.29 kWh/m 3 , respectively. The energy efficiency and exergy efficiency are 87.10 % and 70.07 %, respectively. The exergy destruction is mainly due to irreversible exergy losses in the heat exchangers. The dynamic payback period and levelized cost of energy are 8.36 years and 0.0804 $/kWh, respectively.