A Novel Integrated System for Coupling an Externally Compressed Air Separation Unit with Liquid Air Energy Storage and Its Performance Analysis

Yunong Liu, Xiufen He (), Zhongqi Zuo, Lifang Zheng and Li Wang
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Yunong Liu: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Xiufen He: School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
Zhongqi Zuo: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Lifang Zheng: School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
Li Wang: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China

Energies, 2025, vol. 18, issue 16, 1-29

Abstract: Air separation units (ASUs) are power-intensive devices on the electricity demand side with significant potential for large-scale energy storage. Liquid air energy storage (LAES) is currently a highly promising large-scale energy storage technology. Coupling ASU with LAES equipment can not only reduce the initial investment for LAES, but also significantly lower the operating electricity costs of the ASU. This study proposes a novel modular-integrated process for coupling an externally compressed ASU (ECAS) with LAES. The core advantages of this integrated process are as follows: the liquefaction unit’s storage capacity is not constrained by the ASU surplus load capacity and it integrates cold, heat, electricity, and material utilization. Taking an integrated system with 40,000 Nm 3 /h oxygen production capacity as an example, under liquefaction pressure of 90 bar and discharge expansion pressure of 110 bar, the system achieves its highest electrical round trip efficiency of 55.3%. Its energy storage capacity reaches 31.32 MWh/10 4 Nm 3 O 2 , exceeding the maximum capacity of existing energy storage systems of the ECAS by 1.7 times. Based on a peak-flat-valley electricity price ratio of 3.4:2:1, an optimal economic performance is attained at 100 bar liquefaction pressure, delivering a 7.21% in cost saving rate compared to conventional ASUs. The liquefaction unit’s payback period is 6.39 years—68.1% shorter than conventional LAES. This study aims to enhance both the energy storage capacity and economic performance of integrated systems combining ECAS with LAES.

Keywords: cryogenic energy recovery; externally compressed air separation; liquid air energy storage; peak shaving; power generation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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