## 4 Discussion  
The combined gasification of agricultural biomass waste from the olive seed and industrial plastic waste (basically plastic from luminaires (WEEE), in a mass portion of between 10 and 20%, has been shown to be energetically valorized in a very efficient way, through the production of sintered gas or syngas. The synchronous gas produced in the reactor has a synthesizing calorific value LHV, which is interesting enough to consider the exploitation of this valuable resource, for its industrial exploitation through generation as an alternative form of energy in appropriate rural settings [92]. The results of the economic analysis indicate that there is viability in the construction of a gasification unit [93]. The HLV of WEEE plastics showed good prospects for converting this fuel into energy. For thermochemical energy conversion processes, due to the specificity of the biomass, it is not possible to introduce it only into the reactor. The highly volatile matter makes the plastics of the luminaires analyzed as WEEE more easily not volatilized during pyrolysis and gasification, and lower volatile matter values reduce LHV. More adjacent energy is required for gasification reactions. The high ash content makes WEEE prone to slag in thermochemical conversion systems. As such, downdraft gasification is recommended as this is reported at lower grate temperatures, reducing ash slag trends. The results of this study are perfectly aligned with the results of similar studies in which the joint gasification of biomass and polyethene (PE) residues was observed, where the results showed a synergistic effect on the gas and tar yields when the PE was especially fed with a maximum PE content of 20%. For higher PE content, total gas and H\({}_{2}\) decreased because more chain hydrocarbons with a relatively large molecular size derived from PE volatiles are more difficult to break than oxygenates from biomass pyrolysis [22; 94]. The economic viability of a gasification unit depends on the availability of waste and the size of the unit. In fact, the units with the highest energy generation require a greater quantity of raw material that may not be available in the region, which implies waste transportation costs over considerable distances. This is the reason why gasification systems that use the biphasic combination of agricultural and/or forest resources and industrial wastes from sources close to electricity production centers with gasifiers are especially interesting to favor the circular economy of regions with the ability to supply both resources [66; 95]. Table 16 shows the comparative results of the economic analysis carried out for the three cases studied. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Anos** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** \\ \hline Ct & 2466 & 2466 & 2466 & 2466 & 2466 & 2466 & 2466 & 2466 & 2466 & 2466 \\ \((1+j)^{t}\) & 1.050 & 1.103 & 1.158 & 1.216 & 1.276 & 1.340 & 1.407 & 1.477 & 1.551 & 1.629 \\ \(\frac{\text{Cl}}{(1+j)^{t}}\) & 2348 & 2236 & 2130 & 2028 & 1932 & 1840 & 1752 & 1669 & 1589 & 1514 \\ \(\frac{\text{N}}{\text{t}=1}\frac{\text{Cl}}{(1+j)^{t}}\) & \(-9652\) & \(-7416\) & \(-5286\) & \(-3257\) & \(-1325\) & 514 & 2267 & 3935 & 5525 & 7038 \\ \hline Kinvestment (\(\mathbf{\xi}\)) & \multicolumn{6}{c}{12,000} & & & & & & & & \\ \hline NPV (5 years) (\(\mathbf{\xi}\)) & \multicolumn{6}{c}{\(-1325\)} & & & & & & & & \\ \hline NPV (10 years) (\(\mathbf{\xi}\)) & \multicolumn{6}{c}{7038} & & & & & & & & \\ \hline IRR (\%) & \multicolumn{6}{c}{15.81} & & & & & & & & \\ \hline IbmC & \multicolumn{6}{c}{0.18} & & & & & & & & \\ \hline PBP (year) & \multicolumn{6}{c}{} & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Economic analysis results (80% olive and 20% plastic) (Source: own elaboration). The results in Table 16 show that the best economic results in all economic indicators are for a gasifier that runs on 10% WEEE fuel with 90% olive biomass.