4E analysis of novel direct expansion cycle-organic Rankine cycle-integrated hydrogen refueling station system using liquid hydrogen cold energy

Abstract

The global supply of fuel cell vehicles (FCEVs) is expected to increase to reduce carbon emissions. The number of hydrogen refueling stations (HRSs) is increasing annually, and liquid hydrogen (LH2) is attracting attention as an alternative to overcome the transport and storage limitations of gaseous hydrogen (GH2). If LH2 is supplied to the market, the existing GH2-HRSs can potentially become obsolete because they are not as economically feasible compared with LH2-HRSs. Therefore, in this study, we proposed a new HRS system that integrates direct expansion cycle (DEC) and organic Rankine cycle (ORC) using LH2 cold energy to increase the utilization and economic feasibility of GH2-HRSs. The proposed design was validated through 4E (energy, exergy, economy, and environmental impact) analysis. Compared to the basic design, which did not include LH2 as cold energy, the specific energy consumption (SEC) and exergy efficiency of the proposed design improved by 38.6% and 9.8% to 0.81 kWh/kg H2 and 89.1%, respectively. The minimum selling price improved by 8.3% to $ 1.02/kg H2. In addition, greenhouse gas emissions decreased by 11% from 2.9 kg CO2-eq/kg H2 to 2.6 kg CO2-eq/kg H2, and the life cycle cost (LCC) reduced by 10.5%. Finally, the net present value of the proposed design increased by $535,000, and the payback period decreased by 1 year, indicating that the proposed design was more economically feasible than the basic design. In conclusion, the proposed ORC-DEC-integrated model is practical and feasible in terms of exergy, energy, economy, and environmental impact, allowing the current GH2-HRSs to be used if LH2 becomes the main hydrogen energy.