# Environmental Impact of the Natural Gas Liquefaction Process: An Example from China
## 2 Method
### Life Cycle Impact Assessment  
The environmental impact of LCA is the result of the combined effects of various environmental interference factors. In order to apply LCA to various decision-making processes (such as policy development, product development, etc.), the potential impact on the environment must be assessed. In order to convert environmental emissions into environmental impacts, environmental impacts are classified and characterized in accordance with the framework established by the International Society of Environmental Toxicology and Chemistry and ISO14042 [20,21] (IOS 14042: 2000, Environmental Management-Life cycle assessment-Life cycle impact assessment. The third phase of life cycle assessment is described in IOS 14040). For example, according to ISO14042, [PERSON] et al. [22] calculated and classified the impact categories global warming potential, acidification, and eutrophication of emissions of wastewater and organic household waste in a new city area.  
Therefore, the life cycle environmental impact assessment mainly includes four parts:  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Phase** & **Output** & **Unit** & **Value** \\ \hline \multirow{4}{*}{**A**} & dust & kg/t & 0.0019 \\  & CO\({}_{2}\) & kg/t & 78.7560 \\  & CH\({}_{4}\) & kg/t & 3.6365 \\  & SO\({}_{2}\) & kg/t & 0.0023 \\  & NH\({}_{4}\)\({}^{+}\) & kg/t & 0.0213 \\  & H\({}_{2}\)S & kg/t & 0.0007 \\  & CO & kg/t & 6.3379 \\ \hline \multirow{2}{*}{**B**} & CO\({}_{2}\) & kg/t & 0.3936 \\  & CO & kg/t & 0.1628 \\ \hline \multirow{2}{*}{**C**} & CH\({}_{4}\) & kg/t & 15.1914 \\ \hline \multirow{4}{*}{**Total**} & CH\({}_{4}\) & kg/t & 18.8280 \\  & dust & kg/t & 0.0019 \\  & CO\({}_{2}\) & kg/t & 79.1496 \\ \cline{1-1}  & CO & kg/t & 6.5006 \\ \cline{1-1}  & SO\({}_{2}\) & kg/t & 0.0023 \\ \cline{1-1}  & NH\({}_{4}\)\({}^{+}\) & kg/t & 0.0213 \\ \cline{1-1}  & H\({}_{2}\)S & kg/t & 0.0007 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Emission inventory of liquefied natural gas production in the Shanxi Province (per unit).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Output (kg/t)** & **Henan** & **Sichuan** & **Inner Mongolia** & **Shaanxi** & **Xinjiang** & **Shanxi** & **Ningxia** & **Hebei** \\ \hline CH\({}_{4}\) & 19.3791 & 20.0919 & 21.3899 & 18.3321 & 20.0809 & 18.8280 & 19.7329 & 21.6721 \\ dust & 0.0028 & 0.0063 & 0.0048 & 0.0053 & 0.0038 & 0.0019 & 0.0027 & 0.0035 \\ CO\({}_{2}\) & 80.0021 & 2.5723 & 302.0150 & 353.8802 & 197.6236 & 79.1496 & 360.3098 & 12.8327 \\ CO & 7.1476 & 1.1330 & 28.3336 & 31.3739 & 15.3721 & 6.5007 & 33.9832 & 1.3437 \\ SO\({}_{2}\) & 0.0029 & 0.0366 & 0.0016 & 0.0039 & 0.0235 & 0.0023 & 0.0057 & 0.0039 \\ NH\({}_{4}\)\({}^{+}\) & 0.1325 & 0.0009 & 0.0447 & 0.0229 & 0.2413 & 0.0213 & 0.0058 & 0.2104 \\ H\({}_{2}\)S & 0.0007 & 0.0090 & 0.0008 & 0.0004 & 0.0099 & 0.0007 & 0.0005 & 0.0003 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Emission inventory of the liquefied natural gas production in eight provinces of China (per year).  
Calculation of the environmental impact potential;
* Standardization of the data;
* Weightage of the different types of environmental impact potentials; and
* Calculation of the environmental impact load.  
Combined with the research content of this article, the specific calculation process is as follows.