## 3 Results and Discussion
### CO\({}_{2}\) Emission  
The estimation of CO\({}_{2}\) emission is derived from three components--(i) harvesting operations, (ii) highway transporting/hauling of feedstock and (iii) highway transporting of ethanol fuel. The estimation results are presented in Table 3 and Figure 5.  
The harvesting component includes operating harvesters and trucks/trailers for in-field feedstock transport. Table 3 shows that total daily fuel consumption (FC) for the harvesting operation is about 637.54 gallons per day. Given CC = 2.778 kg/gallon and using Equation (F2), the estimated daily emission amount is 6429.04 kg of CO\({}_{2}\) per day which adds up to 2,346,599.6 kg of CO\({}_{2}\) annually. An annual 2,586.66 tons of CO\({}_{2}\) are released from harvesting operations. The spatial distribution of CO\({}_{2}\) emission depends on the concentration of land used for feedstock production. Figure 5 presents the spatial distribution of CO\({}_{2}\) shown as the column length of each created grid cell for the banagrass production area. There are 61 grid cells created across the entire production land area with the largest cell of 1 km\({}^{2}\) in size. CO\({}_{2}\) emission is aggregated for each cell and stacked into columns. Longer columns indicate higher levels of emission. CO\({}_{2}\) emission in each cell ranges from 30.18 to 75,837.96 kg per year depending on the cell size, given that there are two harvested crops per year. The average CO\({}_{2}\) produced in each cell is approximately 38,000 kg/year. Higher emission levels are found where the concentration of production land is higher. These production land areas are located on the northwest side of the Kohala Mountain road. CO\({}_{2}\) emission is lower for land near coastal areas, northwest of Hawai, where production lands are more scattered. Transporting feedstock and ethanol fuel is a source of CO\({}_{2}\) emission. Figure 5 shows the three trip segments for the highway transporting/hauling of feedstock and ethanol fuel. The transport of feedstock with truck trailers involves trip segments 1 and 2. Trip segment 1 (shown in dark red) is the 26.69 mile road segment that runs from the feedstock production areas on Kohala mountain road to the road leading to the ethanol processing plant. Trip segment 2 connects Kohala Mountain road and the ethanol processing plant (shown in green). The 1.69 mile trip segment 2 is also the initial transport route of ethanol fuel produced at the processing plant back to Kohala Mountain road. This intersection is the beginning of trip segment 3 which measures 25.67 miles in length (shown in purple) and runs to the final destination at Kawaihae port. A large amount of CO\({}_{2}\) is emitted during trip segment 1 due to encountering heavy traffic from trucks carrying feedstock to the processing plant (217 daily trips). An estimated 38,856.36 kg/day of CO\({}_{2}\) is released on this trip segment. Although trip segment 2 is relatively shorter (in distance), the road and the area surrounding the processing plant is fairly congested with trucks arriving and unloading banagrass and tankers loading and leaving filled with ethanol. For the second segment, the daily amount of CO\({}_{2}\) emission is approximately 2460.37 kg for transporting feedstock and 13.63 kg for transporting ethanol fuel. This results in a daily total CO\({}_{2}\) amount of 2474 kg (for segment 2). The third trip segment yields the least CO\({}_{2}\) emission of the three trip segments. This lower emission amount is due to less tanker operations with three round trips per day and an estimated daily total of 388.30 kg of CO\({}_{2}\) for the entire 25.67 mile trip segment. Total daily CO\({}_{2}\) emission is 41,718.66 kg/day for the entire three trip segments. Annually, this amounts to 16,785.22 tons of CO\({}_{2}\). Transport of feedstock with truck trailers has the largest contribution to total CO\({}_{2}\) emission with 41,316.73 kg/day and followed by harvesting operations on banagrass production fields with emission of 6429.04 kg/day.