BIOCHEMICAL CONVERSION: BIOFUELS BY INDUSTRIAL FERMENTATION - Biomass as a Sustainable Energy Source for the Future - page 416

FIGURE 13.9 Fuel prices in Brazil in 2006.
costs of numerous pieces of equipment. Main equipment items are, in order of cost
contribution, the turbines for cogeneration, the sugar mills, the centrifuges (used after
fermentation), and the boiler in the cogeneration section.
The annual cost to run the ethanol plant is 62,719,500 $, from which 85% is due to
sugarcane costs. Much smaller percentages are due to costs of other rawmaterials, main-
tenance, local taxes, and labor. Utilities are not on the list because the required cooling
water is reused almost completely and because energy is generated rather than consumed.
The twomain products are ethanol, at 467.44 $.m -3 , and electricity, at 15.89 $.GJ -1 .
Revenues from these products are 85,980,300 + 9,850,700 = 95,831,100 $ per year.
Any coproducts have not been included in the economic analysis. The investment is
earned back in 2.9 years, which is very acceptable for a factory that may be in operation
for 20 years and which uses proven technology.
A more detailed analysis over the full 20 years indicates that the return on invest-
ment is 17%, which is clearly well above interest rates. In view of a huge expected
demand for bioethanol and the availability of a lot of space for growing sugarcane,
it is not surprising that about 100 bioethanol factories were planned to be built in
Brazil at the time of this analysis.
The profitability of the process is sensitive to the costs of sugarcane and the selling
price of ethanol, but not very sensitive to the selling price of electricity, the investment
cost, or other costs to run the plant. Typically, sensitivity to taxes, subsidies, and
mandates is also high. Figure 13.9 shows a situation where bioethanol is less expen-
sive than fuels from fossil sources.
13.2.9 Ecological and Societal Impact
Like any human activity that is carried out at a very large scale, bioethanol production
will lead to some degree of ecological problems. We can compare these with the