The ammonia synthesis plant is allocated near an inland city due to labor. The synthesis plant includes a water electrolysis plant and a nitrogen cryogenic separation plant. Brine water discharged from RO is generally returned to the sea. As an assumption in this study, a desalination plant is constructed near the sea to return the concentrated seawater to the sea on-site, conveying freshwater to the city via pipeline. In other words, the construction of pipelines necessary to dispose of the concentrated seawater to the sea was omitted. Since this assumption requires a transmission line connecting the seaside desalination plant to the city, the construction and transmission losses of the grid were also included for the estimation of LCCO2 emission. Fig. shows the overall picture of the system boundary conducted in this study. The PV scale (PVscale) is assumed to be sizeable, 100 MWp, since the target is an arid/semi-arid area and is suitable for PV at a large scale. The long-term average of a potential PV electricity generation (PVout) was 4.5 kWh/kWp/day. Thus, the rate of PV operation (PVrate) is 4.5/24 = 18.75%, the typical value for arid and semi-arid areas. The silicon type of PV panel is employed, which has a substantial share of the PV panel market. Both monocrystalline and polycrystalline types have a CO2 emission coefficient, 𝐶 of 0.050 kg-CO2/kWh at the highest, and we adopted that value. Electricity required for seawater desalination (Ewater) was assumed to be 6 kWh/m 3 -H2O. The efficiency for the water electrolysis is 80%, while the hydrogen extracted by the electrolysis is utilized to synthesize ammonia. The energy required for water electrolysis (EH2) is 9.33 kWh/kg-NH3, including desalination energy to obtain the necessary water. And referring to previous calculations by the process simulation software, ASPEN Plus © , 32,33 0.39 kWh/kg-NH3 was used for the cryogenic separation to extract nitrogen from the air (EN2), and 0.78 kWh/kg-NH3 for the ammonia synthesis based on extracted hydrogen and nitrogen (ENH3).