Development of a novel hydrogen liquefaction structure based on liquefied natural gas regasification operations and solid oxide fuel cell: Exergy and economic analyses

초록

To reduce energy and economic consumption in hydrogen (H2) liquefaction cycles, this study develops an integrated system using liquefied natural gas (LNG) regasification for pre-cooling. The system incorporates a six-step Joule-Brayton (J-B) cycle, a solid oxide fuel cell (SOFC), and a carbon dioxide (CO2) power generation cycle, with partial power supplied by wind turbines located in South Korea. The system achieves specific power consumption (SPC) of 6.595 kWh/kgLH2, energy efficiency of 65.61 %, and a production rate of 50 tons per day (TPD) of liquid hydrogen (LH2). The energy efficiencies of the SOFC, CO2 power cycle, and organic Rankine cycle (ORC) are 60.71 %, 47.63 %, and 9.974 %, respectively. Exergy analysis reveals that the highest exergy destruction occurs in SOFC (36.81 %) and heat exchangers (37.98 %). The exergy irreversibility and exergy efficiency (EXE) of the developed system are 38.91 MW and 66.27 %, respectively. Economic analysis, using the annualized cost method (ACS), shows a return period of 5.47 years, an annual net benefit of 26.45 MMUS$/year,andaprimarycostof4.957US$/kgLH2. Sensitivity analysis indicates that reducing LNG prices from 15 to 5 US$/MMBTUlowersthereturnperiodby4.299yearsandtheprimarycostby4.518US$/kgLH2. Additionally, reducing H2 production costs from 4.2 to 2 US$/kgH2decreasesthereturnperiodby3.374yearsandtheprimarycostby3.957US$/kgLH2, while increasing the annual net benefit by 42.88 MMUS$/year. © 2024 Elsevier Ltd

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