Biofuels in Perspective

Bio-Ethanol Development(s) in Brazil 67
Table 4.3 GHG emissions during the ethanol life cycle (kg CO2 equivalent/m 3 of anhydrous ethanol)
Average values Best practices
Productivity (/t) 84.8 92.3
GHG emissions
Fossil fuels 0.22 0.19
Methane and N2O from trash burning 0.11 0.10
Soil N2O 0.07 0.07
Total GHG emissions 0.40 0.36
Avoided GHG emissions
Surplus bagasse use 1 0.14 0.25
Ethanol use 2 2.86 2.81
Total avoided emissions 3.00 3.06
Net avoided emissions 2.60 2.70
Notes: 1due to the substitution of surplus bagasse for fuel oil.
2due to the substitution of ethanol for gasoline.
Source: [29].
non-fossil sources, such as ethanol. Reduction of GHG emissions from ethanol depend on
many factors, e.g. the raw material and the production conditions. For the production of
ethanol from sugarcane under Brazilian conditions, a study by Macedo et al. 29 shows that
the input/output energy ratio (i.e. the amount of energy generated as ethanol regarding
the input of fossil fuels) varies from 8.3 to 10.2. The same study shows that the avoided
emissions of GHG for anhydrous ethanol use are 2.6–2.7 kg CO2 equivalent/liter of ethanol.
Table 4.3 summarizes the main results of this study.
Regarding GHG emissions, the comparison of total emissions of CO2 equivalent in a
‘well-to-wheel’ basis (i.e. considering the life cycle of each fuel) is most accepted. In some
cases emissions from biofuels are as high as that from gasoline, whereas other combinations
of feedstock and conversion processes can reduce ‘well-to-wheel’ CO2 emissions to near
zero (IEA, 2004). There is a general consensus that using bioethanol produced from
sugarcane, according to the Brazilian conditions of production, 80–90 % of the GHG
emissions can be reduced in respect to the use of gasoline (emissions per km traveled). As
a matter of comparison it should be noticed that the use of ethanol derived from grains
(e.g. wheat) brings about 30 % reduction of CO2 emissions. 30,31 Ethanol from sugarcane
(considering Brazilian conditions of production) is the best biofuel alternative concerned
with reduction of GHG emissions.
4.7.2 Impacts on Food Production
As previously mentioned, in Brazil sugarcane production occupies about 10 % of the
current planted area and about 2.5 % of the agricultural land available. More specifically,
ethanol production is responsible for just half of this land use, as just 50 % of the sugarcane
is used for ethanol production.
It is estimated that in Brazil the area available for the enlargement of the agriculture,
without deforestation, is 110 million hectares. Thus, considering that ethanol production
is going to double during the next 5–18 years, the required area would be about 3 % of the
land available as far as current overall productivity is considered.