## 3 Results
### Current Status, Challenges and Future Developments
#### 3.2.5 Renewable Hydrogen Cross-Cutting Issues  
Based on a systematic classification of the literature, four main cross-cutting application categories have been identified in the use of geospatial techniques within the hydrogen sector: hydrogen valleys, safety, leak detection, and training. Table 9 summarizes the main applications and main key challenges associated with geospatial techniques within each of these categories, as classified according to the systematic literature review conducted. As shown, the hydrogen valleys category accounts for 47.8% of the total papers reviewed, 13% focus on improving safety, 26.2% are classified under leak detection applications, and the remaining 13% address cross-cutting issues from a training perspective. Some studies focus on Hydrogen Valleys. The predominant geospatial technique used is GIS, which enhances the accuracy of the location of Hydrogen Valleys, compared to higher-level frameworks, and aids in the design and optimization HVC in the most suitable locations. In this line of research, the study by [PERSON], [PERSON] et al. [169] stands out, proposing a framework that combines GIS with clustering techniques to identify potential locations of Hydrogen Valleys with greater precision than higher-level discretizations such as administrative regions. They compared five different algorithms, with the best results being achieved by the Regionalization with Dynamically Constrained Agglomerative Clustering and Partitioning (REDCAP) method [188]. [PERSON], [PERSON] et al. [172] develop a framework that combines the functionalities offered by a GIS environment such as QGIS and the functionalities of the GAMS optimization environment for designing and optimizing HVC in island territories, minimizing costs, GHG, and risk index. The results demonstrate the potential of GIS as a tool for managing, collecting, and processing geospatial data from different sources, adjusting the data to the needs of optimization. Using the developed framework, the research performs a sensitivity analysis between different optimization objectives. The strategy of minimizing GHG is the one that reports the highest LCOH in all hydrogen production scenarios evaluated. [PERSON], [PERSON] et al. [177] propose a decision-making \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Application** & **Ref.** & \begin{tabular}{c} **Main Geospatial** \\ **Techniques** \\ \end{tabular} & \begin{tabular}{c} **Primary Uses of the** \\ **Geospatial Technique** \\ \end{tabular} & **Challenges** \\ \hline Hydrogen Valleys & [167; 168; 169; 170; 171] & GIS & \begin{tabular}{c} Optimize the location of \\ valleys and supply chains, \\ group regions, \\ analyze distribution \\ \end{tabular} & \begin{tabular}{c} Complexity of finding \\ clusters, heterogeneous \\ data, balancing \\ tational load resolution \\ \end{tabular} \\ \hline Safety & [82; 178; 179] & DT, CV, IRT & Improve security & \begin{tabular}{c} Heterogeneous data \\ sources and formats, \\ variability in environmental conditions \\ \end{tabular} \\ \hline Leak Detection & [180; 181; 182; 183; 184; 185] & DT, VR, IoT, LIDAR & Leak detection & \begin{tabular}{c} Data quality, variability in \\ environmental conditions, \\ reception signal \\ \end{tabular} \\ \hline Training & [30; 186; 187] & \
\begin{tabular}{c} VR, Augmented \\ Reality (AR) \\ \end{tabular} & Educational materials &
\begin{tabular}{c} Adaptation to \\ national contexts \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Summary geospatial techniques applied to cross-cutting issues. model for selecting optimal configurations in hydrogen storage systems linked to wind energy. This model considers the uncertainty inherent in wind power generation, and the different interests and levels of risk aversion of the stakeholder involved. Research classified in the safety category applies geospatial techniques such as CV, DT, and IRT to improve traditional flame propagation characterization techniques.