Configuration optimization of stand-Alone Liquid Air Energy Storage for efficiency improvement

Abstract

Liquid Air Energy Storage (LAES) is one of the most potential large-scale energy storage technologies. At off-peak hours, electricity is stored in the form of liquid air at-196 °C (charging process); at peak hours, electricity is recovered through expanding the liquid air (discharging process). It is found that there is excess heat of compression up to 40% in the LAES, which is directly exhausted. To solve the above problem, two configurations are proposed and compared: The first, denoted by Mode-1, is to use the excess heat to drive an Organic Rankine Cycle (ORC); the second, named as Mode-2, is to add two more expansion stages in the discharging process. Effects of different working parameters on the two configurations are studied. Simulation results show that both Mode-1 and Mode-2 have much higher round trip efficiencies than the baseline system, with the maximum improvement of 12% and 8.6%, respectively.