# Environmental Footprint Assessment of a Cleanup at Hypothetical Contaminated Site
## 5 Results and Discussions
The overall behavior of CO2 emissions is nearly the same as of Figure 5, and it is found to have almost negligible emissions in terms of fossil fuel extraction and electricity transmission when renewable energy is incorporated into the remedial system. The NOx, SOx, HAP and PM emissions are presented in terms of onsite operations, electricity generation, transportation and other offsite operations. It can be observed that the electricity generation and other offsite operations are major contributors in these emissions. The SOx emissions are found to have maximum contribution among all NOx, SOx, PM and HAP. This may be due to the fact that SOx will be emitted when the fuel contains sulphur such as coal and oil. Gasoline is extracted from oil and metals are extracted from ore [23]. For the remedial system, the main sources of SOx emissions are the extraction of fossil fuels for grid electricity, fuels used in transportation, extraction of metals because building steel is used in a very large quantity (292,000 lbs), which makes it a dominant contributor in this category [24; 25; 26]. Although NOx emissions are quite less when compared to SOx, and, primarily, they are only due to burning of fuels in motor vehicles and electric utilities, they cannot be ignored in the overall environmental footprint analysis. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{**CO2 Emissions**} & \multicolumn{2}{c}{**Total HAP Emission**} & \multicolumn{2}{c}{**Total NOx, SOx, PM Emissions**} \\ \hline Scenario & tons & \% Reduction & lbs & \% Reduction & lbs & \% Reduction \\ \hline
1 & 41,741,757 & - & 1119 & - & 219,726 & - \\ \hline
2 & 29,609,307 & 29 & 801 & 28 & 155,511 & 29 \\ \hline
3 & 13,432,707 & 68 & 377 & 66 & 69,891 & 68 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Reduction in emissions via renewable energy integration in the remedial system. Figure 6: Contributors to the CO2 emissions; (**a**) Scenario 1, (**b**) Scenario 2 and (**c**) Scenario 3. Figure 7: Contributors to the total NOx, SOx, PM and HAP emissions; (**a**) Scenario 1, (**b**) Scenario 2 and (**c**) Scenario 3. Based on the above findings, it is highly recommended to incorporate renewable energy sources not only into the remediation activities but also into the fuel mix of grid electricity in Pakistan. Figures 8 and 9 demonstrate the solar and wind energy potential of Pakistan, respectively, which is quite promising for reducing the overall footprint of any activity in general and, in particular, the remediation system under consideration. For example, the annual average mean daily solar radiation in Karachi is in between 5.1-5.4 kWh/m\({}^{2}\)[27], and the wind power class for Karachi is from \"Fair\" to \"Excellent\", with a wind speed between 6.2 and 7.8 m/s [28], depending on the region. Thus, installation of renewable energy systems onsite and purchase of electricity from local renewable energy producers for the remediation of contaminated sites in Karachi is a promising idea which can lead to a reduction in the CO\({}_{2}\), NOx, SOx, PM and HAP emissions even beyond 68%. The research methodology used in this study has limitations. The most significant is that it is a single case study on a hypothetical contaminated site and uses a particular data set for analysis. Therefore, it has potential limitations for systematic generalization. Moreover, the results obtained are based on the share of renewable energy resources in each cleanup scenario and could lead to a completely different set of results if the use of renewable energy resources is increased for more sustainability or decreased due to their limited availability. Figure 8: Solar energy potential of Pakistan [27].