## 2 Materials and Methods
### Process Simulation
#### 2.2.1 Biomass Gasification for Hydrogen Production  
The first simulated thermochemical process was gasification for biohydrogen production. This process is performed taking the following four raw materials into account: (i) CS, (ii) RS, (iii) BEFB, and (iv) CCH. These are identified in the process flowsheet simulation diagram (see Figure 2) as streams 1, 2, 3, and 4, respectively. Table 1 reports the chemical composition and mass flow rate of the primary raw materials for the gasification process. In this sense, the total feedstock flow was 52,289.80 kg/h of combined biomasses.  
These streams are mixed to follow the dryer unit to reduce the moisture content below 10%. This operation is developed before entering the gasification reactor (RX-1). This process is carried out in the gasifier, which operates at 750 \({}^{\circ}\)C and 1 atm. Generally, the products of complete combustion are substances containing nitrogen, water vapor, carbon dioxide, among others. The reaction mechanism in the gasifier involves transforming biomass into coal, and it is transformed into CO and H\({}_{2}\)[37]. First, the outlet reactor stream is sent to the cyclone unit (CYC-1) to separate solids and fluids. The gas-phase flow is cooled down in HX-1 to 15 \({}^{\circ}\)C. As a result, a large amount of water is condensed. Next, the mainstream is sent to an injector (IY-1) to remove dissolved CO\({}_{2}\), in which water is used as the porous medium. Finally, the flow is compressed to 6 bar (CM-1) and sent to a separator (SP-1) to remove water along with the dissolved CO\({}_{2}\)[38].  
The WGS (RX-2) increased biohydrogen production based on H\({}_{2}\) and CO\({}_{2}\) formation from CO and H\({}_{2}\)O. The equilibrium is favorable to the products when the system performs at 205 \({}^{\circ}\)C and 32 atm. The reactor was simulated as a _Rstoic_ model in ASPEN PLUS, considering reported thermodynamic parameters and performance of the equilibrium reactions under the described conditions [39]. Due to the formation of CO\({}_{2}\) in WGS, this substance is highly mixed in the mainstream with H\({}_{2}\) (stream 27). Thus, a filter/membrane (FT-1) was used, which according to [PERSON] et al. [40], produces hydrogen with 99% purity operating at 5 bar and 430 \({}^{\circ}\)C. It is worth highlighting that this device is operative for up to one year, at which it needs a replacement. In this process, hydrogen is produced with a mass flow rate of 1666.8 kg/h; this traduced into global biomass to product yield of 3.20%. Besides, this process consumed energy with a rate of 4,096,267 MJ/h and a total freshwater supply of 410,360 kg/h.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Biomass** & **Mass Flow (kg/h)** & **Cellulose (\%wt.)** & **Hemicellulose (\%wt.)** & **Xylan (\%wt.)** \\ \hline CS & 25,742.20 & 0.29 & 0.20 & 0.13 \\ RS & 19,242.20 & 0.29 & 0.25 & 0.18 \\ BEFB & 7001.80 & 0.42 & 0.13 & 0.12 \\ CCH & 303.60 & 0.28 & 0.29 & 0.12 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical composition and mass flow rate of raw materials in the gasification process.  
Figure 2: Process flowsheet diagram of the gasification process.