## 3 Results
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Hydrogen Production Technology** & **Cost of Hydrogen (\$/kg H\({}_{2}\))** & **Energy Consumption (MJ/kg H\({}_{2}\))** & **Global Warming Impact (Kg CO\({}_{2}\)/kg H\({}_{2}\))** \\ \hline \(\bullet\) & **Greener H\({}_{2}\) production via water electrolysis** & & \\ \hline \(\bullet\) & Wind + Alkaline Electrolysers (AKE) & 5.25–11.92 [29; 33; 59] & 180–280 [60] & 0.0325–4.45 [9; 61] \\ \hline \(\bullet\) & Wind + Proton Exchange Membrane Electrolysers (PEME) & 4–12 27 [26; 29; 62] & 180–280 [60] & 0.0325–3.69 [9; 61] \\ \hline \(\bullet\) & Wind + Solix oxide Electrolysers (SOE) & 6.72–7.77 [60; 63] & 165.6–184 [60; 64] & 0.0325 [61] \\ \hline \(\bullet\) & Wind + Anion Exchange Membrane (AEM) Electrolyzer & 4.48–8.96 [23] & 185–237 [60] & 0.0325 [61] \\ \hline \(\bullet\) & Solar PV + Alkaline Electrolysers (AKE) & 7.00–9.86 [33] & 180–280 [60] & 0.37–8.78 [9; 61] \\ \hline \(\bullet\) & Solar PV + Proton Exchange Membrane Electrolysers (PEME) & 10.13–16.51 [29; 33] & 184–280 [60] & 0.37–7.79 [9; 61] \\ \hline \(\bullet\) & Solar PV + Solix oxide Electrolysers (SOE) & 3.36–8.96 [23] & 165.6–174.2 [64] & 0.37–23 [9; 61] \\ \hline \(\bullet\) & Solar PV + Anion Exchange Membrane Electrolyzer (AEME) & 3.36–8.96 [23] & 185–237 [60] & 0.37 [61] \\ \hline \(\bullet\) & Hydro Power + Electrolyzers (AKE, PEME, OXE, AEME) & 2.70 [65] & 180-216 [48] & 0.72-1.75 [9; 28] \\ \hline \(\bullet\) & Grid Mix + Electrolysers & 4.00–8.81 [23; 24; 25; 26; 26] & 180–216 [48] & 1–30 [9; 25] \\ \hline \(\bullet\) & Nuclear power + PEM & 4.66–7.15 [29] & 180–280 [60] & 1.1 [9] \\ \hline \(\bullet\) & Nuclear power + SOE & 3.79–5 [9; 29] & 165–180 [64] & 0.67–2.1 [9] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cost of H\({}_{2}\) (USD/kg H\({}_{2}\)), energy consumption (MJ/kg H\({}_{2}\)), and GWP (kg CO\({}_{2}\)/kg H\({}_{2}\)) of various water electrolysis technologies with different energy sources. lowest energy efficiency. Carbon capture and storage (CCS) tends to increase the energy consumption and, hence, lowers the energy efficiency of the technology being evaluated. Table 5 shows that solid oxide electrolyzers (SOEs) using electricity from wind turbines, solar PV, and nuclear power seem to have the highest energy efficiency. \begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{1}{c}{**Hydrogen Production Technology**} & \multicolumn{1}{c}{**Energy Efficiency (\%) *} \\ \hline \(\bullet\) & **Emerging technologies** \\ \hline \(\bullet\) & \(\bullet\) Biomethane pyrolysis & 40–56 [23; 69] \\ \hline \(\bullet\) & ESMR & 70 [42] \\ \hline \(\bullet\) & SMC & 49.4–82.2 [26] \\ \hline \(\bullet\) & Solar thermal + thermochemical decomposition & 20 [29] \\ \hline \(\bullet\) & Nuclear + thermochemical decomposition & \\ \hline \(\succ\) S-I & 42–52 [25; 44] \\ \hline \(\succ\) HyS & 49 [25] \\ \hline \(\succ\) Cu-Cl & 43 [44] \\ \hline \(\succ\) Mg-Cl & 45 [25] \\ \hline \(\bullet\) & Bio-photolysis & 10–15 [41; 56; 57] \\ \hline \(\bullet\) & Ammonia thermal decomposition via fixed bed & 78–80 [45] \\ reactor & \\ \hline \(\bullet\) & Ammonia thermal decomposition with & 87–90 [45] \\ PSA-membrane separation & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Energy efficiencies (%) of emerging clean H\({}_{2}\) production technologies.