# Scenario-Based Techno-Economic Analysis of Steam Methane Reforming Process for Hydrogen Production
## 3 Results and Discussion  
### Capital and Operating Costs  
Table 4 shows the capital and operating costs of the six scenarios (see Tables S5-S8 in the Supplementary Materials for the equipment costs calculated in Sc 1-4, respectively). The TCI and total operating cost in Sc 1 are the lowest of all scenarios, at $902,183 and $181,063/y, respectively (the TCI in Sc 1, 5, and 6 are calculated equally). This is due to the low overall conversion from natural gas to hydrogen, which decreases the capital costs of the hydrogen production and hydrogen purification process areas and the operating costs owing to the reduced consumption of deionized water. The low temperature of the WGS reaction causes a high equilibrium value, thus increasing the amount of H\({}_{2}\) produced from CO. Therefore, the low temperature (250 \({}^{\circ}\)C) of the WGS reaction in Sc 2 leads to a larger reactor and a higher catalyst consumption, which in turn increases the TCI and total operating cost by 4.8% and 0.92%, respectively, compared to Sc 1. In Sc 3, two WGS reactors are employed, each operating at high (450 \({}^{\circ}\)C) and low (250 \({}^{\circ}\)C) temperatures. The \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Values** & **References** \\ \hline Natural gas price (\$/t) & 239.0 & [41] \\ Ru–Ni/Al\({}_{2}\)O\({}_{3}\) catalyst (steam reformer) (\$/kg) * & 25.0 & [24] \\ Cu/Fe\({}_{3}\)O\({}_{4}\)–Cr\({}_{2}\)O\({}_{3}\) catalyst (WGS reactor) (\$/kg) * & 25.0 & [24] \\ Adsorbent (\$/kg) * & 2.0 & [24] \\ Deionized water (\$/t) & 14.5 & [42] \\ CO\({}_{2}\) emission allowances (\$/t) & 29.0 & [43] \\ CO\({}_{2}\) capture cost (\$/t) & 70.0 & [43] \\ CO\({}_{2}\) selling price (\$/t) & 80.0 & [43] \\ Plant financing by equity (\%) & 40.0 & [39] \\ Plant life (y) & 20 & [39] \\ Income tax rate (\%) & 35.0 & [39] \\ Internal rate of return (\%) & 10.0 & [39] \\ Interest rate for debt financing (\%) & 8.0 & [39] \\ Term for debt financing (y) & 10.0 & [39] \\ Plant depreciation (y) & 7.0 & [39] \\ Average labor rate (\$/h) & 20.0 & [39] \\ Land (\% of fixed capital investment) & 2.0 & [39] \\ Working capital (\% of fixed capital investment) & 5.0 & [39] \\ On-stream percentage after startup (\%) & 90.0 & [39] \\ Startup time (y) & 0.5 & [39] \\ Revenue and costs during startup & & \\ Revenue (\% of normal) & 50.0 & [39] \\ Variable costs (\% of normal) & 50.0 & [39] \\ Fixed costs (\% of normal) & 75.0 & [39] \\ Construction period (y) & 1.0 & [39] \\ \hline \hline \end{tabular}  
* 10% of the catalyst and adsorbent is refurbished every three months at a cost equivalent to 40% of its original value.  
\end{table} 
Table 3: Major economic parameters and assumptions. TCI and total operating cost in Sc 3 increase by 19% and 1.5%, respectively, above those in Sc 1 because of the additional WGS reactor. The TCI and total operating costs of Sc 4 are 35% and 16% higher than those of Sc 1, respectively, owing to the installation of the additional compressor. In particular, the consumption of electricity and deionized water is significantly increased owing to the low vapor pressure of the additional compressor. Sc 5 and 6 consider CO\({}_{2}\) emissions and CO\({}_{2}\) capture, increasing the total operating costs. In the six scenarios, the hydrogen production area accounts for the largest proportion of the TCI: 34.1%, 34.6%, 36.7%, and 23.6% in Sc 1, 2, 3, and 4, respectively. This is because multiple reactors are used, including the reformer and the WGS reactor, which accounts for 67.4% of the total installed equipment cost in Sc 1. The next largest contributor is the hydrogen purification area, owing to the high cost of the PSA unit. As for the operating cost, the feedstock cost is the most dominant cost contributor in the six scenarios, accounting for 67.4%, 66.7%, 65.6%, and 56.7% of the total operating cost in Sc 1, 2, 3, and 4, respectively.