Flexible integration of liquid air energy storage with liquefied natural gas regasification for power generation enhancement

摘要

Liquid Air Energy Storage (LAES) is one of the most promising energy storage technologies for achieving low carbon emissions. Our research shows that the LAES produces a considerable amount of excess heat that cannot be cost-effectively utilised in a standalone LAES system. On the other hand, the regasification of liquefied natural gas (LNG) often leads to waste of a large amount of high-grade cold energy. Therefore, this paper proposes the integration of the LAES with the LNG regasification process via a Brayton cycle (denoted as LAES-Brayton-LNG), where pressurized propane is used as both the heat transfer fluid and storage material for the LNG cold energy. The excess heat from the LAES works as the heat source and the waste cold from the LNG regasification as the cold source for the Brayton cycle. Such an integrated LAES-Brayton-LNG system does not need to change the existing LAES system configuration, and the LNG regasification process is independent of the LAES system, thus allowing operation flexibilities. Our analyses show that the flexibly integrated LAES-Brayton-LNG system achieves a system exergy efficiency of 57% and could improve the system exergy efficiency of the standalone LAES system by 14.4%. What's more, it has an electrical round trip efficiency of 70.6%, which is 56.5% higher than that of the standalone LAES system. Hence, the proposed LAES-Brayton-LNG system is comparable with other large scale energy storage technologies in terms of the electrical round trip efficiency.