## 3 Results and Discussion  
Mapping the operating bioethanol plants in the Netherlands, it was found that none of these feedstocks are used for the production of bioethanol; but most of them are focused on corn stover, a feedstock that contains high amounts of cellulose (43.7%) and hemicellulose (23.7%) [64]. The investigation of the viability and sustainability of bioethanol plants is required, to give insights into new pathways for boosting the bioeconomy [65; 66; 67; 68]. There will be more fermentable sugars available that result in higher ethanol production, and thus, revenue. After simulating the processes in SuperPro Designer, the data in Table 4 were acquired. Here it can be seen that ethanol production from GS yields the highest revenues. This can be a result of the significantly higher dry matter content (92.50%) when compared to SBP (70.36%), or the slightly higher efficiencies of carbohydrate polymer conversion in the GS. Therefore, the plant treating GS will obtain the highest revenue. The executive summary for SBP and GS for the production of bioethanol can be found in Table 4.  
From Table 4, it can be concluded that a bioethanol plant that treats SBP is not economically viable since the NPV is negative. The revenue per year is not large enough to cover the total capital investment and the operating costs per year, which results in an NPV of \(-\)671,000 \(\epsilon\). The high capital costs are due to the building and constructing costs (22.91%) and equipment purchase costs (18.15%), which total of \(\epsilon\)1,061,000 \(\epsilon\). The operation costs mainly consist of utilities (57.78%) which are 621,000 \(\epsilon\). The high utility costs mainly result from the high amount of steam required to heat the vessel for 30 min at 121 \({}^{\circ}\)C in the pretreatment step. The costs are 328,134 \(\epsilon\) per year for only V-101, which accounts for 71.62% of the total amount of steam used. Besides, since SBP is not vastly available, 105,000 \(\epsilon\) per year must be paid to store the SBP to have a constant supply. If it was vastly available, the operating costs would decrease to 970,000 \(\epsilon\) resulting in a unit production cost of 0.68 \(\epsilon\)/kg ethanol. In this situation, the IRR is 5.86%, the NPV 207,000 \(\epsilon\) and the payback time 13.8 years, meaning that it would be economically viable. As can be seen in Table 4, a bioethanol plant treating GS is not economically viable. Due to the long cycle time, the batches are larger resulting in a larger fermentation vessel. To process the volume, 3 fermenters are needed, which results in high equipment purchase costs and high direct fixed capital costs. Thus, it is a high capital investment because most of the investments consist of the equipment costs. The equipment purchase costs are 18.45% of the total capital investment. Together, with the engineering and construction costs, which are 22.71% of the total capital investment, they are the largest expenses. Besides high equipment costs, more energy is needed since the equipment used is larger. Furthermore, the utility costs and thus operating costs are higher, since the pretreatment requires heating at 180 \({}^{\circ}\)C, and this needs to be done with high-pressure steam instead of regular steam. High-pressure steam costs 18.80 \(\epsilon\)/MT and normal steam 11.28 \(\epsilon\)/MT, whereby the costs increase to 434,483 \(\epsilon\). Besides the use of high-pressure steam, 4,734,017 metric tons of cooling water are needed to cool the pretreated GS in the fermentation vessel since that process must be executed at 37 \({}^{\circ}\)C, which further contributes to the high utility costs (70.71% of the total operating costs). Since the costs are too high compared to the revenue, it is not possible to calculate the IRR nor the payback time. When comparing the different feedstocks used, it can be concluded that SBP is the most viable. Although the numbers are not positive now, better technology/procedures for storing the SBP could provide a way out.