A novel small scale liquefied natural gas production process at filling stations: Thermodynamic analysis and parametric investigation

In the last years, the increased demand of the energy market has led to the increasing penetration of renewable energies in order to achieve the primary energy supply. However, simultaneously natural gas still plays a key role in the energy market, mainly as gaseous fuel for stationary energy generation, but also as liquefied fuel, as an alternative to the diesel fuel, in vehicular applications. Liquefied Natural Gas (LNG) is currently produced in large plants directly located at the extraction sites. In this study, the idea of realizing plug & play solutions to produce LNG directly at vehicle's filling stations has been investigated. A novel process of LNG production for filling stations has been analyzed, consisting in a single stage Joule-Thompson isenthalpic expansion process, with intercooled compression. Furthermore, the presented layout has been developed with the purpose of optimizing the energy consumption of the plant, obtaining moderately pressurized LNG. With the aim of investigating the feasibility of this novel LNG generation process, a thermodynamic analysis has been carried out and presented in this study. Moreover, the minimization of energy consumption has been investigated with a parametric analysis, in order to optimize the LNG production and to maximize the efficiency of the process. Furthermore, novel performance indicators have been defined, in order to account the efficiency of the LNG production process. Results of the optimization analysis show that, with the proposed layout, an energy consumption equal to about 1.9 MJ/kg of produced LNG can be achieved.