Volume 24: Sustainable Energy Solutions for a Post-COVID Recovery towards a Better Future: Part VII

Harnessing Liquid Air Cold Energy for Performance Enhancement of Hydrogen Liquefaction Process Amjad Riaz, Muhammad Abdul Qyyum, Gwangsik Kim, Moonyong Lee*

Abstract

As an energy vector, hydrogen faces bulk storage and transportation challenges due to its low volumetric energy density. Following the footsteps of liquefied natural gas, hydrogen is also liquefied prior to transportation. Liquid nitrogen is usually used as the refrigerant in the precooling cycle; however, alternate candidates are also being studied. Liquid air, which is already drawing attention as a standalone cryogenic energy storage system, is one such candidate as enormous cold energy is available in its regasification phase or the discharge half-cycle. In the present study, liquid air is considered the refrigerant stream in the precooling section of the hydrogen liquefaction process. A well-known commercial simulator Aspen HYSYS® v12.1 is used for this unique concept’s design and performance analysis. Composite curves analysis is performed to analyze the proposed integrated scheme’s performance graphically. The specific energy consumption of 8.52 kWh/kg LH2 has been obtained in the unoptimized base case.

Keywords Hydrogen liquefaction, hydrogen economy, ortho-para conversion; hydrogen energy network, energy storage system; liquid air energy system