Coupled system of liquid air energy storage and air separation unit: A novel approach for large-scale energy storage and industrial gas production
Zhikang Wang, Xiaoyu Fan, Junxian Li, Yihong Li, Zhaozhao Gao, Wei Ji, Kairan Zhao, Yuan Ma, Liubiao Chen, Junjie Wang
Abstract
Liquid air energy storage (LAES) emerges as a promising solution for large-scale energy storage. However, challenges such as extended payback periods , direct discharge of pure air into the environment without utilization, and limitations in the current cold storage methods hinder its widespread adoption. Moreover, the current liquid air energy storage power and transmission load cannot flexibly adjust to meet grid demand. As the foundation of heavy industry, the energy-intensive air separation industry is characterized by high operating costs. In response to these challenges, this paper proposes a coupled system of liquid air energy storage and air separation unit (LAES-ASU). The aim is to enhance system economics, reduce the scale of cold storage units, significantly decrease the operating costs of air separation units, and provide flexibility in energy storage capacity adjustment according to grid demand. LAES-ASU leverages liquid oxygen for cold energy storage, optimizing processes to minimize air separation unit power consumption during peak hours, thereby substantially reducing operating costs. Additionally, LAES-ASU adjusts power generation by varying air separation unit loads to meet peak demand. Energy, exergy, and economic analyses reveal compelling findings: the implementation of LAES-ASU slashes cold storage unit investment costs by 62.05 % compared to traditional LAES, shortening the payback period to 3.49 years, and reducing air separation electricity costs by 50.87 % to 56.17 % . During the energy storage process , LAES-ASU consumes 19.92 MW of electricity and generates 4.21 MW during energy release, effectively facilitating peak-shaving. The study underscores the economic viability and potential for large-scale application of LAES-ASU, providing valuable insights for industrial-scale LAES deployment.