In evaluating the economy of the system employed in the integrated pilot plant, the cost and method of collecting raw biomass material must be considered. From the viewpoint of reducing the burden of biomass collection, we examined the possibility of producing fuel alcohol at a site adjacent to a cane sugar production plant. Production was evaluated based on the unit processes demonstrated in the bench-scale plant.
A cane sugar plant at Mackay, situated on the east coast of Australia, was selected as the site. The scale of the plant is as follows:
|
Sugar cane processed |
8000 (thousand tons/year) |
|
Production of sugar |
1000 |
|
Generation of bagasse |
2000 |
|
Generation of molasses |
200 |
Alcohol production was hypothetically established on a model scale at 72,000 kL/year (alcohol concentration: 99.5%), and was evaluated both with and without the use of a highly efficient bagasse boiler.
Figure 3.24 - Plot plan of an alcohol production plant
Table 3-11 Alcohol Production Costs (yen/litre) Based on Bagasse to Molasses Ratios
|
Bagasse/molasses ratio |
With bagasse boiler |
Without bagasse boiler |
|
100/0 |
119.64 |
134.47 |
|
72/28 |
102.99 |
114.03 |
|
50/50 |
92.57 |
100.03 |
Table 3-12 Constitution of Costs at A Bagasse to Molasses Ratio of 72:28
|
Cost |
With bagasse boiler |
Without bagasse boiler |
|
|
Variable cost |
Raw materials |
8.50 |
23.21 |
|
Chemicals |
27.74 |
27.74 |
|
|
Service |
10.18 |
10.18 |
|
|
Fixed cost |
Equipment |
39.38 |
39.38 |
|
Labor-fixed cost |
12.85 |
9.18 |
|
|
Transportation |
4.34 |
4.34 |
|
|
Total |
102.99 |
114.03 |
|
From the plot plan of a hypothetical production plant shown in Fig. 3-24, a potential alcohol production plant would require an area of 300 m x 600 m = 1.8 x l0 m, including a stock yard. Table 3-11 shows the total cost in terms of the ratio of bagasse to molasses, while Table 3-12 gives the cost breakdown for a bagasse to molasses ratio of 72:28.
