Modeling and optimization of LNG cold energy-assisted carnot battery system

Abstract

Carnot batteries (CB) have been developed as a prospective solution in the future energy scenario as a large-scale electricity energy storage technology. In this study, the cold energy of liquefied natural gas (LNG) is integrated into CB system, which is working as heat sink in the integrated system. Different working fluids with varied operating pressure are performed in charging and discharging cycle separately. Additionally, the influence on system thermodynamic and economic performance from key parameters is discussed and the design working conditions is determined. Upon analysis, the integration of LNG cold energy and CB system enables a significant enhancement on overall energy storage efficiency, as well as the economic benefits based on net present value (NPV) method. According to the design case, R717 and R152a are selected as the optimal working fluids for charging and discharging processes respectively. The system exhibits a overall efficiency of up to 165.8% with the energy storage capacity of 520kW, and the system NPV reaches 2183$/kW with the yearly LNG supply of 30380t. The findings in this paper offer a promising solution for LNG receiving terminal that the total revenue could exceed three times higher than before by adding the energy benefits.