## Results and Discussions  
### Life Cycle Inventory of the Selected Alternatives and the Conventional Production Process  
Table 3 shows a summary of the LCI results obtained at the outlet of the ER process assuming a final concentration of FA at the bottom of the distillation column of 85% wt. for A1.1, A1.2, and A1.3 as ER processes. Additionally, there are summarized values related to the commercial route of production sourced from Ecoinvent [27] (A\({}_{\text{CONV}}\)) and the alternative of the direct catalytic reaction of CO\({}_{2}\) and H\({}_{2}\) (A\({}_{\text{JCR}}\)). The values summarized in Table 3 are grouped as electrode/catalyst materials, raw materials, products (formic acid 85% wt.), other valuable products obtained in the process (H\({}_{2}\) and O\({}_{2}\)), and energy and heat demand (steam). This study considers that other salts and acids used in ER process can be perfectly recirculated.  
It can be seen in Table 3 that values of ER energy and steam are expected to be the main resources contributing to the overall CF. The electricity consumption by ER per mass unit of FA ranges between 4.59 kWh\(\cdot\)kg\({}^{-1}\) and 11.93 kWh\(\cdot\)kg\({}^{-1}\), with A1.2 alternative having the best conditions in terms of electric consumption. The differences are mainly due to the combinations of reaction rates and cell potentials at a certain current density. A1.2 has the lowest flow rate (for pumping) and the highest Faradaic Efficiency. These values are well over the minimum theoretical electricity consumption of 1.72 kWh\(\cdot\)kg\({}^{-1}\) (originally 1.803 MWh\(\cdot\)ton\({}^{-1}\) when related to CO\({}_{2}\) as reported in [17]). A1.1 alternative exhibits the highest consumption of steam by unit of mass of FA 401 MJ\(\cdot\)kg\({}^{-1}\), as the FA concentration  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**A\({}_{\text{ER}}\)**} & \multicolumn{3}{c}{**A\({}_{\text{JRC}}\)**} & \multicolumn{1}{c}{**A\({}_{\text{CONV}}\)**} \\ \cline{3-6}  & **UNITS** & **A1.1** & **A1.2** & **A1.3** & & \\ \hline Electrode/Catalyst & & & & & & \\ TOTAL & kg (10\({}^{-6}\)) & 1.30 & 9.92 & 14.9 & 3.75 & 15.60 \\ Raw materials & & & & & & \\ CO\({}_{2}\) & kg & 0.95 & 0.96 & 0.96 & 0.83 & - \\ H\({}_{2}\)O & kg & 1.10 & 0.59 & 1.41 & 0.56 & 0.60 \\ CO & kg & - & - & - & - & 0.61 \\ CH\({}_{3}\)OH & kg & - & - & - & - & 0.04 \\ Products & & & & & & \\ HCOOH & kg & 1.00 & 1.00 & 1.00 & 1.00 & 1.00 \\ H\({}_{2}\)O & kg & 0.18 & 0.18 & 0.18 & 0.06 & 0.18 \\ By-products & & & & & & \\ H\({}_{2}\) & kg (10\({}^{-3}\)) & 59.00 & 3.00 & 92.00 & \(-\)0.06 & - \\ O\({}_{2}\) & kg & 0.82 & 0.37 & 1.09 & 0.48 & - \\ Energy & & & & & & \\ _Electricity_ & & & & & & \\ ER & kWh & 11.80 & 4.59 & 11.93 & - & - \\ Pump & kWh (10\({}^{-3}\)) & 7.35 & 1.24 & 0.63 & - & - \\ Compression & kWh & 0.15 & 0.04 & 0.11 & - & - \\ TOTAL & & 11.80 & 4.59 & 11.90 & 4.07 & 0.29 \\ _Heat demand_ & & & & & & \\ Steam & MJ & 401.00 & 65.18 & 25.67 & 10.03 & 22.77 \\ \hline \hline \end{tabular}
\end{table}
Table 3: LCI for the ER of CO\({}_{2}\) according to the three selected experimental data references (A1.1, A1.2, and A1.3), the conventional commercial process sourced from Ecoinvent [27] (A\({}_{\text{CONV}}\)), and an alternative CCU process based on the catalytic conversion of CO\({}_{2}\) and H\({}_{2}\)[7] (A\({}_{\text{JCR}}\)). The functional unit is 1 kg FA.  
is lower than the concentration reached by the other references (A1.2 and A1.3 alternatives). As it was mentioned above, surpluses of renewable energy from PV solar energy were supposed to be used for supplying energy to ER, pumping, and compression. The wide range of consumption of steam per mass unit of FA (from 401 MJ\(\cdot\)kg\({}^{-1}\) to 25.7 MJ\(\cdot\)kg\({}^{-1}\)) highlights the significance of the purification step. As it was expected, the higher FA concentration at the outlet of the ER cell, the lower steam consumption (A1.3 scenario).