(An) approach to liquid hydrogen supply chain considering effect of ortho-para conversion

Abstract

This study is an efficient liquid hydrogen (LH2) supply chain design for transportation and use of the LH2 as energy medium. The LH2 causes additional energy consumption due to liquefaction process itself and exothermic reaction in the process induced from intrinsic nature of hydrogen (ortho-para conversion) at a cryogenic temperature of -253 ℃. This is the biggest factor that lowers the efficiency and economy of the LH2 supply chain. First, this study analyzed the effects of the concentration of isomers (ortho and para) on the LH2 supply chain for the liquefaction process, marine transportation and land transportation. The conceptual design of the LH2 tanker for marine transportation and the LH2 truck for land transportation was carried out. For the conceptual design, it is analyzed following variables: liquefaction energy, pressurization behavior, and loading limit. Based on this, the economics of the transportation system including the liquefaction plant were evaluated using the life-cycle cost. Second, it is suggested a hydrogen refueling process using the cold energy of the liquid hydrogen for a hydrogen refueling station (HRS) as the end user of the LH2 supply chain. The proposed system is designed to evaluate the energy consumption, exergy analysis, availability, and its economics for comparison with the existing gas storage refueling process (GH2 storage), and liquid storage refueling process (LH2 storage). Finally, this study analyzed the entire LH2 supply chain considering the ortho-para conversion and proposed a method for efficient operation in the LH2 supply chain.