# Environmental Impact of the Natural Gas Liquefaction Process: An Example from China
## 3 Results and Discussion
### Environmental Impact Potential of Natural Gas Liquefaction at Annual Output  
Based on the calculation of the environmental impact potential of natural gas liquefaction per unit of production, we calculated the GWP, AP, EP, POCP, DU, and Total EI Potential weights of Xinjiang, Inner Mongolia, Shaanxi, Shanxi, Ningxia, Henan, Sichuan, and Hebei during the natural gas liquefaction process at annual output levels. The following six conclusions can be drawn from Figure 6.  
First, according to the annual GWP results of the eight provinces, China's annual GWP was estimated to be about 1,257,526 p-a. Inner Mongolia and Shaanxi had the largest annual GWP weights, accounting for 33.59% and 28.69%, respectively (Figure 6a). In contrast, Henan had the smallest annual GWP weight, accounting for 2.59%. Inner Mongolia and Shaanxi had the highest annual GWP weights, owing to their higher LNG production and higher greenhouse gas content in the gas source components. Second, according to the annual AP results of the eight provinces, China's annual AP was estimated to be about 40,333 p-a. Xinjiang, Hebei, and Inner Mongolia had the largest annual AP weights, accounting for 33.40%, 20.87%, and 20.40%, respectively (Figure 6b). The total annual AP weights of the five remaining provinces accounted for less than 30%, of which Ningxia accounted for only 1.41%. Therefore, the AP weights and natural gas liquefaction output were not completely proportional. The main reason for this disproportion is that the components of the Hebei and Xinjiang  
Figure 6: Weightage of the various environmental impact potentials of the eight provinces in natural gas liquefaction stage (per year): (**a**) Global Warming Potential (GWP), (**b**) Acidification Potential (AP), (**c**) Eutrophication Potential (EP), (**d**) Photochemical Ozone Creation Potential (POCP), (**e**) Dust Potential (DP), and (**f**) Total Environmental Impact Potential. natural gas sources had a relatively high acid content, especially SO\({}_{2}\) and NH\({}_{4}\)+. Therefore, although LNG production was not high, the AP weights remained high. Third, according to the annual EP results of the eight provinces, China's annual EP was estimated to be about 43,437 p-a. Xinjiang, Hebei, and Inner Mongolia had the largest annual EP weights, accounting for 33.11%, 22.48%, and 21.80%, respectively (Figure 6c). However, Ningxia and Sichuan had extremely small annual EP weights of 0.95% and 0.09%, respectively. Therefore, the EP weights of Xinjiang and Hebei were not directly proportional to the liquefaction output of these two provinces. The main reason for this was that the content of NH\({}_{4}\)+ in the components of the natural gas sources in these two provinces was relatively high. Fourth, according to the annual POCP results of the eight provinces, China's annual POCP was estimated to be about 10,760,516 p-a. Inner Mongolia and Shaanxi had the largest annual POCP weights, accounting for 36.38% and 34.64%, respectively (Figure 6d). The total annual POCP weight of the six remaining provinces was less than 30%. The smallest two values were for Henan and Sichuan, which accounted for 1.55% and 1.38%, respectively. The POCP weights of the provinces were not completely proportional to their natural gas production. However, because the natural gas liquefaction output and gas source components in Inner Mongolia and Shaanxi were relatively high in photochemical ozone synthesis substances, these two provinces had the largest annual POCP weights. Fifth, according to the annual DP results of the eight provinces, China's annual DP was estimated to be about 2420 p-a. Inner Mongolia and Shaanxi had the largest two annual DP weights, accounting for 32.07% and 31.73%, respectively (Figure 6e). The remaining six provinces accounted for smaller annual DP weights. Therefore, the DP weights of each province were not completely proportional to natural gas production.