## 3 Results
### Hydrogen Production via Hydrolysis  
The water-aluminium reaction produces gases at various rates depending on the composition, structure and electrolyte content. Considering the sample content, gas analysis is rather essential. Thus, we have to see what gases are produced during the reaction with the selected electrolyte.  
For the SOW sample, we measured the gas composition at the beginning of the reaction and at a later stage; the composition of the analysed gases is visible in Table 1. We can see that 0.2% of methane was detected at the beginning of the reaction, with 97.4% hydrogen, 0.3% O\({}_{2}\), 1.2% N\({}_{2}\), and 0.1% CO\({}_{2}\). At the end of the reaction, methane was still present at 0.2%, with water vapour at 0.1% and 99.6% hydrogen.  
On the other hand, for RM hydrolysis, at the beginning, 98.3% hydrogen was detected and 0.0% methane, in addition to 0.4% N\({}_{2}\), 0.1% O\({}_{2}\), and 1.9% water. Then, the reaction was left to run till full completion. Contrary to SOW, methane was not present; that is, it could be up to 0.09 wt.% of content, which functionally means there was no methane. Hydrogen composed most of the collected gas, as shown in Table 1.  
Hydrolysis using the HDC sample shows a steady production of gas and heat during the reaction. It starts with the release of CO\({}_{2}\) and H\({}_{2}\), as can be seen in Table 1. Then, it was left in the reactor overnight to allow the reaction to fully run out and determine the totality of reaction products. Even at long durations, methane evolution was detected, as well as nitrogen, which decreases the gas ratio. Therefore, the amount of H\({}_{2}\) decreases to 92.5%. Methane, ethane, and CO\({}_{2}\) are the most prominent impurities in the reaction. It is noteworthy that some N\({}_{2}\) might have been introduced via a leak in the reactor, as the increase is relatively large. Methane is the significant impurity of the gas, with a concentration of 0.4%.  
For gas use in power production via a fuel cell, the reaction was run separately using a similar setup to that described in our previous work [17]. To test if the gas composition changed, each hydrolysis reaction was run multiple times, where the produced gas was collected into a RESTEK gas bag and tested, then, depending on the impurity composition, fed to the fuel cell. The gas bag collection system was not vacuumed. Thus, we expected a higher air/nitrogen content. The results are shown in Table 2. Contrary to the vacuumed system, only HDC shows methane content; other samples essentially have only air and water as impurities. In SOW, there is a large amount of air, as seen in the N\({}_{2}\) content and lower concentration of hydrogen. Alw1 gas content from the hydrolysis reaction is summarised in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**SOW**} & \multicolumn{2}{c}{**RM**} & \multicolumn{2}{c}{**HDC**} \\ \hline
**Element** & **Start** & **End** & **Start** & **End** & **Start** & **End** \\ \hline Argon & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 \\ \hline Carbon Dioxide & 0.1 & 0.0 & 0.2 & 0.2 & 0.2 & 0.2 \\ \hline Hydrogen & 97.4 & 99.6 & 98.3 & 97.2 & 98.3 & 92.5 \\ \hline Methane & 0.2 & 0.2 & 0.0 & 0.0 & 0.0 & 0.4 \\ \hline Nitrogen & 1.2 & 0.0 & 0.4 & 0.5 & 0.4 & 5.2 \\ \hline Oxygen & 0.3 & 0.0 & 0.1 & 0.2 & 0.1 & 1.0 \\ \hline Water & 0.7 & 0.1 & 1.9 & 1.9 & 0.9 & 0.5 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Gas analysis, where methane presence is detected.