# Electricity Generation in LCA of Electric Vehicles: A Review
## 3 Spatial boundary.
#### 3.2.2. Attributed System Modelling
Considering that the EVs represent an emerging technology, it is quite exemplar that no ALCA studies analyse future energy scenarios, while they are rather linked to a blurred present (not defined in the time scope) and rely on outdated data. [PERSON] et al. [45] consider also a future electricity mix set in 2050 but the results for this time horizon are not made explicit, along with the mix composition. Figure 5: Number of analyses sorted by time horizon. Some studies do not make explicit the time horizon of their study. In this case the year of the electricity dataset used in the analysis has been considered, if available; otherwise they are accounted in the first column. Note that each study can have more than one time-horizon in its analysis. It is instead common the use of scenarios where the electricity is assumed to be supplied entirely from a single technology, or a bunch of homogeneous technologies (e.g., all RES, all fossil fuels) also known as stylised states according to the definition by [87]. These technologies are generally at the extremes of the polluting bar, in a sort of stress test of the potential benefits (or disadvantages) of implementing such a technology. Sixteen among the review papers investigate how EVs perform when charged on a specific technology or when are charged solely by certified RES energy (see Figure 6 and Table 3). \begin{table}
\begin{tabular}{l l l l} \hline \hline  & **Stylised State** & **g CO2-eq/kWh** & **g CO2-eq/km** \\ \hline [PERSON] et al. [14] & Biomass & - & 110.35 \\ [PERSON] et al., 2014 [2] & CNG & 642 & 93.5 (WtW) \\ [PERSON] et al., 2017 [40] & CNG & - & 93.5 (WtW) \\ [PERSON] et al., 2017 [15] & Coal & 1180 & 482 \\ [PERSON] et al., 2014 [2] & Coal & 1080 & 157 (WtW) \\ [PERSON] and Sullivan 2008 [39] & Coal & 954 & 274 (WtW, PHEV) \\ [PERSON] et al., 2017 [40] & Coal & - & 157 (WtW) \\ [PERSON] et al., 2015 [23] & Coal (average efficiency in 2012) & - & 371 \\ [PERSON] et al., 2015 [23] & Coal (average efficiency in 2030) & - & 308 \\ [PERSON] and Marques 2012 [27] & Coal (desulfurisation and denitrification & 1050 & 225 (Compact BEV) \\ [PERSON] et al., 2012 [1] & Coal (Ecolnvent Dataset) & 1260 & 231 \\ [PERSON] et al., 2012 [1] & Coal IGCC & 936 & 185 \\ [PERSON] et al., 2012 [1] & Hydro & 6.12 & 48 \\ [PERSON] and Sullivan 2008 [39] & Hydro & 0 & 0 (WW, PHEV) \\ [PERSON] et al., 2015 [23] & Hydro (average efficiency in 2012) & - & 66.9 \\ [PERSON] et al., 2015 [23] & Hydro (average efficiency in 2030) & - & 55.8 \\ [PERSON] et al. [48] & Marginal mix in a scenario with & 247.26 (last trip charging) & 23.4 (WW) \\  & dedicated RES for additional EV loads & 245.42 (DSM charging) & 10.7 (WW) \\ [PERSON] and [PERSON] 2008 [39] & Natural gas & - & 184 (WW, PHEV) \\ [PERSON] et al., 2015 [23] & Natural gas (average efficiency in 2012) & - & 186 \\ [PERSON] et al., 2015 [23] & Natural gas (average efficiency in 2030) & - & 155 \\ [PERSON] et al., 2012 [1] & NGCC & 504 & 120 \\ [PERSON] 2011 [49] & NGCC & 430 & 55 (WtW) \\ [PERSON] et al., 2015 [23] & Nuclear (average efficiency in 2012) & - & 68 \\ [PERSON] et al., 2015 [23] & Nuclear (average efficiency in 2030) & - & 56.7 \\ [PERSON] et al., 2014 [2] & Oil & 885 & 128.5 (WW) \\ [PERSON] and Sullivan 2008 [39] & Oil & 892.8 & 262 (WW, PHEV) \\ [PERSON] et al., 2015 [57] & PV & 89 & - \\ [PERSON] et al., 2015 [23] & PV (average efficiency in 2012) & - & 87.2 \\ [PERSON] et al., 2015 [23] & PV (average efficiency in 2030) & - & 72.6 \\ [PERSON] et al. [14] & Wind & - & 151.2 \\ [PERSON] 2012 [27] & Wind & 23 & 50 (Compact BEV) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Energy GHG intensity and GHG of BEV in stylised states across the literature. Figure 6: Number of stylised states presented in the literature sorted by energy source. However, even for a single fuel, a huge variability in GHG emission is noticed, due to technology differences (CC plants, CHP plants, etc.). [PERSON] et al.