Thermodynamic analysis of Liquid Air Energy Storage integrated with a serial system of Organic Rankine and Absorption Refrigeration Cycles driven by compression heat

The rapid increase in application of intermittent renewable energy generation has stimulated the development of energy storage system to guarantee a stable supply in electricity grid. As a large-scale storage technology, Liquid Air Energy Storage (LAES) technology has attracted many attractions in recent years due to it offers many unique advantages including high energy density, mature technologies based and geographical-constraint free. However, current LAES has relatively low round trip efficiency (less than 60%) and still needs improvement. In the LAES system, a large amount of compression heat is recovered and stored over 470 K during air liquefaction, and then is used to heat high pressure air before turbines to increase output power when electricity is needed. The effective use of compression heat is a key method to increase the total net output and round trip efficiency of LAES. Currently, only 58-78% of compression heat can reheat the high-pressure air while the rest is idle and wasted. Thus, taking advantage of the excessive compression heat to generate extra electricity has enormous potential to enhance net output and round trip efficiency of the LAES. This paper proposes an innovative liquid air energy storage system integrated with a serial system of Organic Rankine Cycles (ORC) and Absorption Refrigeration Cycles (ARC). In the proposed system, excessive compression heat can be to drive the ARC to create a low temperature environment for the ORC, meanwhile, it works as the heat source of the ORC. Through the serial system, more electricity is generated. Results show that relatively higher round trip efficiency could be obtained, with 3-9% enhancement compared with the current LAES.