Abstract: This paper concerns with liquid air energy storage particularly the use of different cycles and optimization. A large scale standalone liquid air energy storage system could achieve a round trip efficiency of ~60%. By using a combined Heylandt cycle and Rankine cycle, we show, through simulation with Aspen Plus software, a cycle efficiency of 64.5%. For further improvement of the performance of the combined cycle, thermal efficiency and exergy efficiency of the Rankine cycle and the Heylandt cycle were analyzed separately. We foundthat the maximum exergy loss was associated with the heat exchangers, and the exergy losses of the Rankine cycle and the Heylandt cycle accounted for 13.1% and 61.8%, respectively. As a consequence, the enhancement of the performance of heat exchangers holds the key to improving the whole combined cycle efficiency.

Key words:  energy storage, liquid air, Heylandt cycle, Rankine cycle, cycle efficienc