## 3 The Results
### Results of the Literature Review
\begin{table}
\begin{tabular}{c c c c c} \hline
**ClusterID** & **Size** & **Silhouette** & **Label (LLR)** & **Average Year** \\ \hline
0 & 51 & 0.869 & Comprehensive review & 2019 \\ \hline
1 & 38 & 0.871 & Increasing electric vehicle & 2019 \\ \hline
2 & 37 & 0.914 & Charging behavior & 2017 \\ \hline
4 & 23 & 0.986 & Integrating electric vehicle & 2022 \\ \hline
6 & 19 & 0.982 & Considering battery energy wear & 2018 \\ \hline
8 & 17 & 1.000 & Stochastic connection & 2012 \\ \hline
9 & 16 & 0.987 & To-grid ancillary service & 2013 \\ \hline
10 & 14 & 0.984 & V2G uncertainty & 2021 \\ \hline
12 & 13 & 1.000 & Integrity & 2013 \\ \hline
18 & 7 & 1.000 & Multi-level charging station & 2020 \\ \hline \end{tabular}
\end{table} 
Table 3: Summary of the largest 10 clusters. Figure 5: Number of studies by countries. Leading journals have played fundamental roles in advancing the technological application of V2G and, consequently, in the research to define the attributes/variables necessary to predict the charging demand of EV [27]. The analysis highlights the significant contributions of various researchers. Table 4 lists the six authors with the highest number of citations who have made significant contributions to V2G research. The central year of the citations is also given. Taking into account their countries of origin, it is evident that the results are consistent with the geographical analysis previously presented, highlighting the roles of the United States and China as the main actors in the V2G studies. Regarding the country analysis, the review of the literature follows the trend of incentives and policies implemented by different governments. In fact, the findings indicate that EVs are increasingly being promoted as a key solution to reducing greenhouse gas and pollutant emissions. Numerous countries are supporting the adoption of EVs through incentives and technological advancements, with more than 17 nations aiming to achieve 100% zero emission vehicles by 2050 [28]. The global EV market is growing rapidly, and \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Author** & **Institution** & **Country** & **Citation** & **Year** & **Centrality** \\ \hline [PERSON] & University of Delaware & USA & 212 & 2008 & 0.10 \\ \hline [PERSON] & University of Washington & USA & 95 & 2012 & 0.10 \\ \hline [PERSON] & Tsinghua University & China & 89 & 2018 & 0.02 \\ \hline [PERSON] & Georgia State University & USA & 86 & 2017 & 0.02 \\ \hline Clement-Nyns[PERSON] & K.U. Leuven & Belgium & 75 & 2010 & 0.07 \\ \hline [PERSON] & The University of Tokyo & Japan & 72 & 2012 & 0.06 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Authors with the highest number of citations. Figure 6: Collaboration network between countries. technology is improving for both personal and commercial transport. In general, there are many pilot projects, with a significant percentage in Europe [29]. The projects vary significantly in scale and learning objectives, but more and more pilot projects are including service experimentation and user interaction. In Italy, there are currently no active V2G pilot projects. This underscores the importance of the theoretical exploration of V2G technology and the creation of predictive models for its implementation in Italy. Therefore, a significant starting point for researchers is the analysis of scientific studies carried out in leading countries on the ecological transition and adoption of EVs. Based on this analysis, it is therefore possible to focus on the need to investigate the use of electric vehicles, as well as their parking, to assess the potential to participate in V2G. After identifying the main clusters, the analysis focused on the clusters with the highest \"silhouette\" index, and within each, the studies with the highest number of citations have been reviewed.