Systems design and analysis of liquid air energy storage from liquefied natural gas cold energy

Abstract

The cold recovery of liquefied natural gas (LNG) is an important issue and power generation is widely recognized as a potential option. However, the amount of generated power from LNG regasification is relatively small for use as a primary energy source to the energy grid. Therefore, using recovered LNG cold energy as an auxiliary energy source for the energy grid can be more appropriate than directly supplying power to the energy grid. By applying an energy storage system to the LNG regasification process, the recovered energy can be flexibly released to the energy grid when required. Among various energy storage technologies, liquid air energy storage (LAES) is one of the most promising large-scale energy storage systems. This study proposes a combined LAES and LNG regasification process. In this system, the air is cooled via heat exchange with LNG and compressed by using the generated power from LNG. This power is produced by both direct and indirect methods: LNG direct expansion and organic Rankine cycle with a mixed working fluid, respectively. This is a novel work in which both direct and indirect power generation methods to the LNG regasification process are combined with the energy storage system. According to the performance comparisons amongst various energy storage systems combined with the LNG regasification process, this proposed system is the most efficient proposed in the literature. Moreover, economic evaluation is performed using a net present value to investigate the feasibility of the proposed system.