Conceptual design and exergy analysis of combined cryogenic energy storage and LNG regasification processes: Cold and power integration

• Published in: Energy (Oxford) 2017-12, Vol.140, p.106-115
• Main Authors: Lee, Inkyu, Park, Jinwoo, Moon, Il
• Format: Article
• Language: English
• Subjects: Cold storage; Conceptual design; Cryogenic energy storage; Energy consumption; Energy storage; Exergy; Exergy analysis; Gasification; Heat exchange; Heat transfer; Internal energy; Liquefaction; Liquefied natural gas; LNG regasification; Low temperature physics; Natural gas; Performance enhancement; Process design; Process integration; Thermodynamics; Working fluids
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2017.08.054

This study aims to develop an efficient cryogenic energy storage (CES) process using the exergy from liquefied natural gas (LNG) regasification. While LNG has low internal energy, it has high exergy because of its cryogenic characteristics, and much of this exergy is wasted in the process of regasification. Thus, this work focuses on the recovery of LNG cold exergy to store cryogenic energy using air as a working fluid. The cold exergy of LNG is transferred in two forms: cold transfer by heat exchange to liquefy air, and shaft work transfer by direct expansion of LNG to compress the air. Thermodynamic analysis of the proposed process is carried out in three exergy flow steps: the LNG regasification step, the air liquefaction step, and the air expansion step. In addition, the proposed system has an advantage which system can store and release the energy simultaneously. Therefore, daily produced energy by CES system is more than double compare to the most recent contributions that have divided operation modes for energy storage and release. This study not only proposes an efficient energy storage process that can generate power flexibly but also highlights further possibilities for performance enhancement by thermodynamic analysis. •The integrated Cryogenic energy storage (CES) and liquefied natural gas (LNG) regasification process is proposed.•Exergy efficiency of the air storage process is 94.2%, and the air release process is 61.1%.•The specific power output per 1 kg of LNG is about 160.92 kJ.