Biofuel contribution to mitigate fossil fuel CO2 emissionsC.docx

Biofuel contribution to mitigate fossil fuel CO2 emissions:
Comparing sugar cane ethanol in Brazil with corn
ethanol and discussing land use for food production
and deforestation
Luiz Pinguelli Rosa,a� Christiano Pires de Campos,b� and
Maria Silvia Muylaert de Araujoc�
COPPE/UFRJ, Cidade Universitária Centro de Tecnologia,
Bloco G, sala 101 Ilha do
Fundão, CP 68501, 21945-970 Rio de Janeiro, Rio de Janeiro,
Brazil
�Received 8 October 2008; accepted 30 April 2009; published
online 30 June 2009�
This paper compares the use of sugar cane and corn for the
production of ethanol,
with a focus on global warming and the current international
debate about land use
competition for food and biofuel production. The indicators
used to compare the
products are CO2 emissions, energy consumption, sugar cane
coproducts, and de-
forestation. The life cycle emission inventory as a
methodological tool is taken into
account. The sustainability of socioeconomic development and
the developing
countries’ need to overcome barriers form the background
against which the Bra-
zilian government energy plans are analyzed. © 2009 American
Institute of

Physics. �DOI: 10.1063/1.3139803�
I. INTRODUCTION
The use of biofuel as a substitute for fossil fuel has became a
crucial issue today for several
reasons, including �a� the increasing price of the oil barrel and
the limited oil resources in the
world, �b� the increase in fossil fuel consumption in
developing countries, particularly in China, as
a result of high economic growth, �c� environmental
constraints, mainly greenhouse gas �GHG�
emissions and climate change, �d� the challenges of
sustainable development and the elimination
of extreme poverty in developing countries, and �e� the
potential impacts of biofuels on crops for
food supply, as well as on deforestation.
A literature review was developed to consider the results of
recent publications about the role
of the biofuel production in the world for programs of GHG
emission reductions and sustainable
environmental performance. “Depending on the methodology
used to account for the local pol-
lutant emissions and the global greenhouse gases emissions
during the production and consump-
tion of both the fossil and biofuels, the results can show huge
differences. If it is taken into
account a life cycle inventory approach to compare the different
fuel sources, these results can
present controversies. For example, a comparison study
involving the American oil diesel and
soybean diesel developed by the National Renewable Energy
Laboratory presents CO2 emissions
for the biodiesel which are almost 20% of the emissions for the
oil diesel: 136 g CO2 / bhp-h for

the biodiesel from soybean and 633 g CO2 / bhp-h for the oil
diesel.”
1
According to other authors2 the quite relevant issue of the
carbon content and the related GHG
emission factors also shows huge differences. It is very
important “to determine the size of carbon
pools in native habitats and the amount of carbon lost from
these pools when converted to crop
production.3 The relevant carbon pools differed depending on
the native habitat and the biofuel
crop.” A study developed by Fargione et al. about land clearing
and the biofuel carbon debt says
a�Electronic mail: [email protected] Tel.: 55-21-25627024.
Tel./FAX: 55-21-22701580.
b�Electronic mail: [email protected] Tel.: 55-21-38656188.
c�Electronic mail: [email protected] Tel.: 55-21-22993080.
JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY
1, 033111 �2009�
1, 033111-11941-7012/2009/1�3�/033111/21/$25.00 © 2009
American Institute of Physics
http://dx.doi.org/10.1063/1.3139803
http://dx.doi.org/10.1063/1.3139803
http://dx.doi.org/10.1063/1.3139803
http://dx.doi.org/10.1063/1.3139803
http://dx.doi.org/10.1063/1.3139803
that “when not presented in the literature, dry forest biomass
was assumed to be 50% carbon, and

US grasslands dry biomass was assumed to be 45% carbon.”4 It
is important to highlight that these
percentages can result in significant errors and need further
research.
Another recent study shows that agricultural crops most
commonly used at present for biofuel
production and climate protection can readily lead to enhanced
greenhouse warming. This state-
ment relates to N2O. “When the extra N2O emission from
biofuel production is calculated in
‘CO2-equivalent’ global warming terms, and compared with the
quasicooling effect of ‘saving’
emissions of fossil fuel derived CO2, the outcome is that the
production of commonly used
biofuels, such as biodiesel from rapeseed and bioethanol from
corn �maize�, depending on N
fertilizer uptake efficiency by the plants, can contribute as
much or more to global warming by
N2O emissions than cooling by fossil fuel savings.”
5
Oil still ranks first place among the primary sources of energy,
representing 35% of total
primary energy in the world, followed by coal, with more than
20%, and natural gas, with a
slightly lower percentage. Combined, these three fossil fuels
were responsible for three quarters of
the world’s energy budget.6 Biomass was dominant throughout
the 19th century, being surpassed
by coal at the transition from the 19th to the 20th century, and
then by oil by the mid-1900s.6
Although its share went down over time, until the 1970s, it has
remained nearly constant over the

past few decades, at about 10%. One of the reasons for this was
the increase in liquid biofuels as
substitutes for oil, compensating for the decrease in the
traditional uses as firewood.
The oil barrel price went up from US$10 in 1999 to US$70 in
2006, reaching over US$100 in
2007 and US$140 in 2008, and then coming down to less than
US$100. One factor that explains
this behavior is the forecast of limited world oil reserves and
production in the near future.7
Although such forecast is uncertain, it does influence
policymakers and the market.
Other factors that influence the oil economy and related policies
include the increase in energy
consumption �EC� in developing countries, especially in
China, and the Organisation for Eco-
nomic Co-operation and Development �OECD� dependence on
oil import. Last but not least, we
should also mention environmental pressures related to global
warming as a result of present and
historical GHG emissions from fossil fuels.8–11
Besides the Asian developing countries, after more than a
decade of hard monetarist restric-
tions and a very low development rate, several Latin America
countries, including Brazil, have had
significant economic growth over the past years. Nonetheless,
in spite of the recent income im-
provement of part of the poor, social inequality persists in many
countries. Left-wing or center-left
political parties did win governmental elections in several Latin
American countries, and the
resulting political changes that were implemented implied a

more direct role of the government in
the energy sector.
The next section discusses the increasing GHG emissions from
fossil fuels in the world and
shows that, according to the 2007 IPCC Report, CO2 from fossil
fuels is the main contributing
factor for global warming �Sec. II�. Section III introduces the
case of Brazil, considering energy
uses and GHG emissions in the country. Section IV deals with
biofuel production in Brazil.
Section V discusses sugar cane ethanol in Brazil and compares
it with corn ethanol. Section VI
deals with land use, competition with food production, and
deforestation. Section VII includes the
final comments.
II. WORLD CO2 EMISSIONS FROM FOSSIL FUELS
According to the IPCC Fourth Assessment Report,12 there was
a 70% increase in the world’s
GHG emissions during the 1970–2004 period. CO2 emissions
increased to 80%; 77% of GHG
emissions in 2004 were anthropogenic. The highest
contributions for the increase in GHG emis-
sions during the period came from the electric energy system
�145%�, followed by transportation
�120%�, industry �65%�, and change in land uses and
deforestation �40%�. The combined per
capita emission from the US and Canada was 27 tons of CO2
equivalent, while in Latin America,
it was 8 tons and in Africa, 4 tons.
Therefore, we could state that CO2 is responsible for most GHG
emissions, while energy

033111-2 Rosa et al. J. Renewable Sustainable Energy 1,
033111 �2009�
continues to be the most important source of emissions,
including electricity generation, transpor-
tation, and industrial activities. Here is the present situation in
the world:
�1� Until now, the developed countries have not reduced their
emissions in order to reach the
goals of the Kyoto Protocol, whose period of commitment
started in 2008 and will end in
2012.
�2� Developing countries tend to increase their emission as
their economy grows because they
follow the developed countries’ consumption patterns.
Figures 1 and 2 illustrate both statements. Figure 1 shows the
energy per capita in different
countries. The horizontal axis �X� in Fig. 1 shows the gross
domestic product �GDP� per capita,
while the vertical axis �Y� shows the energy intensity of the
economy �energy per GDP� in such a
FIG. 1. Energy per capita �E / population = E / GDP � GDP /
population� Data are from 1980, 1985, 1990, 1995, 2000, and
2005. Source: Calculated from Ref. 13.
FIG. 2. CO2 Emissions per capita from energy �CO2 /
population = E / population � CO2 / E� Data are from 1980,
1985, 1990,
1995, 2000, and 2005. Source: Calculated from Ref. 13.

033111-3 Ethanol, climate change, land use... J. Renewable
Sustainable Energy 1, 033111 �2009�
way that the product XY = energy per capita, represented by the
hyperbolas at constant values. The
points represent the years 1980, 1985, 1990, 1995, 2000, and
2005 for each country �see legend�.
As shown, developed countries have higher GDP per capita and
higher energy per capita. The
courses followed by them from 1980 to 2005 are quite parallel
to the hyperbolas of constant
energy per capita, which means that this rate will remain the
same along this period. Spain, on the
other hand, has shown a significant increase in energy per
capita. There was a reduction in the
intensity of energy in most developed countries, but the GDP
per capita growth was high. The
GDP is expressed in current dollars; nevertheless, the growth of
GDP per capita over this 25 year
period was impressive.
In the developing countries, the situation is quite different: very
low GDP per capita �X axis�
and very low energy per capita �hyperbolas near XY axis�.
Figure 1 shows an increase in energy
per capita, but GDP per capita in general remained very low.
Figure 2 shows CO2 emission per capita from EC in different
countries. The horizontal axis
�X� represents energy per capita, while the vertical axis �Y�
depicts the carbon intensity of the
energy system in such a way that the product XY = CO2
emission per capita, represented by the

hyperbolas at constant values. The points represent the same
years and the same countries as Fig.
1.
The developed countries have higher energy per capita and
higher CO2 emission per capita
from the energy system. Their CO2 emissions per capita from
1980 to 2005 are not as simple as
for energy per capita. Developing countries have very low
energy per capita �X axis� and very low
CO2 emission per capita from energy transformation
�hyperbolas closer to XY axis�. There was a
trend to increase CO2 per capita.
III. ENERGY USES AND GHG EMISSIONS IN BRAZIL
In developing countries, EC in the higher income classes is
often high; however, once the
majority of the population is poor, their EC level is very low.
Therefore, there is strong inequality
in EC and GHG emissions by family within each country,
mirroring inequality in income distri-
bution. The same inequality existing between developed
countries and developing ones is repro-
duced within each country between the high income and the low
income classes.14 Such is the case
of Brazil. As of 2003, an estimated 12 million Brazilians did not
have access to electricity, 88% of
which are rural residents. In most of the north region of Brazil
�in the Amazon�, there is no grid.
There are isolated systems burning diesel oil for electricity
generation, which in 2006 spent US$2
billion in subsidies. The governmental program Luz para todos
�Power for All� is reducing such
discrepancies.15

One in every eight Brazilians owns a car.16 According to Table
I, the consumption of energy
by cars in 2007 in Brazil was 22.49 Mtoe �megatons of oil
equivalent� �13.87 Mtoe of gasoline
+8.62 Mtoe of ethanol�, while the consumption of diesel oil in
transportation for that same year
was 28.83 Mtoe,17 from which it is estimated that roughly 10
Mtoe were consumed for public
transportation of passengers. Therefore, 12.5% of the Brazilians
consume in their cars more than
twice the fuel consumed for public transportation, which is used
mainly by 87.5% of the popula-
tion, i.e., by those families that do not own a car. The above
calculation does not include the
electric energy use in public transportation or the use of diesel
in private cars because they were
considered insignificant in Brazil. Assuming that CO2 emission
from ethanol is zero and CO2
TABLE I. EC in transport �Brazil, 2007�. Source: Ref. 17.
Mtoe
Diesel 28.83
Gasoline 13.87
Ethanol 8.62
Othersa 5.58
aIncludes fuel oil, aviation kerosene, natural gas, and
electricity.
033111 �2009�

emission from gasoline is approximately equal to that from
diesel, CO2 emission from every car
owner is 9.7 times higher than that of an individual that does
not own a car.
The recent discovery of large oil fields in Brazil by Petrobras—
the so-called Pre-sal area in off
shore deep waters—places the country in a very unique
situation, entirely different from the world
trend. Brazilian oil reserves may reach �30 – 80� � 109
barrels, as compared to the current 14
� 109 barrels. However, in Brazil, renewable energy is an
important component of the energy
matrix. In 2006, renewable energy amounted to 42%, while its
shares in the rest of the world were
about 10% and 5% in the OECD countries �Fig. 3�.
The renewable energy sources used in large scale in Brazil are
hydroelectric energy, alcohol
�ethanol� from sugar cane, sugar cane bagasse, firewood, and
charcoal �Fig. 4�. Lines in Fig. 4
depict the energy fluxes from energy sources to consumption
sectors in the boxes located in the
middle. Boxes at the top represent fossil energy, including
nuclear energy, while renewable
sources are at the bottom, some of them used in large scale.
FIG. 3. Renewable and fossil fuel energy. Source: Ref. 17.
FIG. 4. Energy flows from source to consumption: fossil and
renewable energy in Brazil.

Among the primary energy sources in the top section of Fig. 4,
oil, natural gas, and coal are
responsible for CO2 emissions, but nuclear is not, unless the
entire life cycle is taken into account.
Another important observation is that, among the renewable
energy sources in the bottom, hydro-
electric energy emits GHG. Although hydropower plant
emissions are not included in national
inventories of GHG emissions, experimental measures carried
out in hydropower reservoirs by a
COPPE research group found methane and carbon dioxide
emissions, although generally at levels
far lower than those of thermopower plants.18
There are in Brazil programs for alternative sources and
conservation of energy to avoid GHG
emissions involving oil and electricity government-owned
companies: �1� the programs for con-
servation of energy adopted by Eletrobras and Petrobras; �2� a
program implemented by Eletrobras
to buy electric energy from wind, biomass, and small hydro
�3.3 GW� started in 2003; �3� a blend
of biodiesel in diesel oil, according to regulations, starting from
2% and increasing to 3%, involv-
ing Petrobras and private companies; and �4� incentives for
flex-fuel vehicles that use either
ethanol or gasoline in any proportion.
IV. BIOFUELS IN BRAZIL AND AUTOMOTIVE ETHANOL
There are different sources of biofuels, including �1� forest
resources �deforestation and forest
management�, �2� energy agriculture �forest plantation,
sugar cane, corn, vegetable oils�, �3� ag-
riculture wastes �sugar cane bagasse, rice waste, and others,

animal wastes�, and �4� urban wastes
�solid waste and garbage�. Table II indicates the biomass raw
materials with the corresponding
technologies, products, and uses in Brazil, as well as the fossil
fuels that are replaced.
In rural areas, direct combustion of firewood is important for
cooking. This kind of firewood
use is not equivalent to deforestation because families in rural
areas often collect branches of trees,
without destroying them.
The use of charcoal in steel industry is important for avoiding
GHG emissions. For each ton
of steel, about 2 tons of CO2 are emitted from coke and coal.
Charcoal use in steel production
avoids that emission and allows a capture of 1 ton of CO2 from
the atmosphere due to the carbon
fixed in forest plantation stock. Therefore, the net balance when
replacing coke with charcoal is
the subtraction of 3 tons of CO2 from the atmosphere for each
ton of steel. This means that if
TABLE II. Uses of bioenergy in Brazil.
Technology Biomass raw material Products Main use
Substitution of fossil fuels
Combustion Firewood Heat Cooking LPG
Sugar cane, bagasse, and trash Industry Fuel oil
Electric power Natural gas
Wastesa
Bioconversion:
• Fermentation Sugar cane Ethanol Transport Gasolineb

• Anaerobic digestion Wastes Biogas Potential use Natural gas
Chemical and thermal:
• Pyrolysis Wood Charcoal Industry Coal and oil
• Gasification Biomass Synthesis gas Industry Natural gas
• Esterification
Vegetable oil
and other materialsc Biodiesel Transport Diesel
• Cracking Vegetable oil Diesel R&D Diesel
• Hbiod Vegetable oil Diesel Pilot Diesel
Hydrolysis �2nd generation� Biomass Ethanol R&D Gasolineb
aIncludes urban solid wastes, lixivia from the pulp and paper
industry, waste from rice, and others.
bIt can also be a diesel oil substitute with the use of some
additives; in Brazil, gasoline is blended with 25% of ethanol,
besides the use of pure ethanol in flex-fuel vehicles.
cIncludes animal fat waste, garbage, and microalgae �R&D�.
dTechnology of Petrobras for processing vegetable oil in oil
refineries.
033111 �2009�
one-third of steel would be produced with charcoal, the steel
industry in Brazil could have zero net
emissions. However, nearly half of the firewood for charcoal
used in steel production comes from
deforestation and only half comes from forest plantation. This is
a problem that has yet to be
solved.

Ethanol is the most important biofuel in Brazil. The Brazilian
Alcohol Program started in 1975
after the first oil shock, and, in its first phase, consisted of
using ethanol as an additive to gasoline.
After the second oil shock in 1979, there was a second phase in
which, besides its use as an
additive to gasoline, ethanol replaced gasoline in cars whose
Otto cycle engines were adapted
accordingly. The historical factors contributing for the policy of
incentives to start the Alcohol
Program included the need of reducing the commercial balance
deficit, affected by crude oil
imports. Besides, the program also created new jobs in the sugar
cane agroindustry and reduced air
pollution through the elimination of plumb as an additive to
gasoline once ethanol allows high
compression in the engine.
By 1985, more than 90% of new car sales were of ethanol fueled
cars, but in the 1990s there
was a shortage of ethanol in the country. A temporary solution
was the adoption of a ternary mix
composed of ethanol, methanol, and gasoline to supply part of
the market.19,20 The result was the
lack of consumer confidence in ethanol and the consequent
reduction in new car sales with ethanol
fueled engines to 11% in 1990, 2% in 1995, and only 1% in
2000.21 The reasons for the ethanol
shortage were the decrease in crude oil price and the lack of
continuity in the governmental policy
regarding ethanol.
From 2003 on, flex-fuel car production in Brazil ramped up the
automotive use of ethanol.
The flex-fuel cars were initially produced in the US in the
1980s, but the technology developed by

Brazilian automotive industry engineers in the country is
innovative.22 It uses sensors already
existing in the car and matches their readings against
information stored in an on board computer
to adjust the engine to the fuel. The American flex-fuel cars
used a special sensor to identify the
fuel and adjust the engine accordingly, but it was expensive and
unpractical for Brazil, where the
car fleet is dominated by small and middle sized compact, low-
cost cars.22
Figure 5 depicts ethanol consumption in Brazil. The total
ethanol consumption exceeded 15
� 109 l in 1998, progressively decreasing to 10 � 109 l in
2001, then going up again. It reached
17 � 109 l in 2006, and in 2007 ethanol production exceeded 20
� 109 l, of which 3.3 � 109 l
were exported.17 Figure 6 shows the evolution of new car sales.
It points out the dominance of
ethanol-fueled cars in the mid-1980s, a decrease in the 1990s,
and the exponential growth of
flex-fuel cars after 2003, encouraged by the high relative price
of gasoline due to the raise in the
crude oil price internationally, as well as by global warming-
related pressures, among other fac-
tors.
FIG. 5. Evolution of ethanol consumption in Brazil ��109 l /
year�. Source: Ref. 17.
The cost of ethanol in Brazil went down from US$20/GJ in 1980

to US$6/GJ in 2006,
corresponding to US$40/barrel of oil23 following a learning
curve. Therefore, while subsidies were
necessary to start the program, they are no longer needed.
V. LIFE CYCLE CO2 AVOIDED WITH THE USE OF
ETHANOL AS A SUBSTITUTE FOR
GASOLINE
A. Net avoided GHG emissions: Comparing sugar cane ethanol
with corn ethanol
A problem regarding ethanol in some OECD countries, as well
as in China, is the fact that
corn ethanol is used in some countries. From the perspective of
global warming and GHG
emissions—for instance, CO2 emissions from fossil fuel
burning—corn ethanol is less effective
than sugar cane ethanol as a substitute for gasoline.
The advantage of biofuels is that, as biomass grows, it captures
the CO2 emitted by biofuel
combustion in car engines from the atmosphere. However, the
production of 1.3 GJ of ethanol
from corn uses up 1 GJ of fossil fuel.24 That is, from each
energy unit transformed in heat through
corn ethanol combustion, 0.77 energy unit is spent for the
production of ethanol from corn. The
issue is the consumption of fuel oil for ethanol distillation, as
shown in Fig. 7. The variables are
as follows:
• A, emissions from fossil fuels to make the equipment and for
the construction of buildings for
corn and ethanol production in a life cycle analysis;

• B, emissions from fossil fuels to produce fertilizers and other
materials;
• C, emissions from fossil fuels in corn production �includes
emissions from diesel oil in
tractors, mechanization equipment, and trucks for
transportation� and from the soil;
• D, capture of CO2 from the atmosphere as corn grows;
• E, emissions from fossil fuels in ethanol distillation;
• F, emissions from electricity generation in the grid for ethanol
production;
• G, emissions from ethanol combustion in cars; and
• H, gross avoided emissions from the use of ethanol as gasoline
substitute in a life cycle
analysis.
Figure 7 shows that there is a balance between CO2 capture
from the atmosphere in corn
plantation �D� and CO2 emissions �G� from ethanol
combustion in cars:
FIG. 6. Sales of gasoline, alcohol, and flex-fuel cars in Brazil.
Source: Ref. 21.
033111 �2009�
balance of CO2 capture by corn: D = G . �1�
However, there are emissions from fossil fuel use in the
production of corn and ethanol. Therefore,
if H is the CO2 that would be emitted by the use of ethanol as a
gasoline substitute:

net avoided CO2 by corn ethanol: N = H − A − B − C − E − F .
�2�
On the other hand, sugar cane has enough of biomass surplus to
generate heat and electricity
in the ethanol production process �Fig. 8�. For each 1 GJ of
fossil fuel consumed in sugar cane and
ethanol production, there is an average of 9 GJ of ethanol �it
can reach 11 GJ at best�.24 Therefore,
for each unit of energy transformed in heat when sugar cane
ethanol is burned in car engines, only
0.11 unit of energy from fossil fuel is spent for the production
of ethanol. Besides the bagasse,
sugar cane has a significant amount of trash �leaves and top�,
which is often burned before
harvesting in order to facilitate the job of workers, but trash can
be recovered when mechanization
is used instead of manpower in the harvesting of sugar cane.
The use of mechanization in sugar
cane plantations is increasing in the State of São Paulo, but this
reduces employment levels.
The variables represented in Fig. 8 are as follows:
• A, emissions from fossil fuel to make the equipment and for
the construction of buildings for
cane and ethanol production in a life cycle analysis;
• B, emissions from fossil fuel to produce fertilizers and other
materials;
• C, emissions from fossil fuel in sugar cane production �it
includes emissions from diesel oil
in tractors, mechanized harvesting, and trucks for
transportation� and from soil �N2O�, as

well as CH4 and N2O emissions from burning sugar cane
�trash� before harvesting;
• C�, CO2 emissions from burning sugar cane before
harvesting;
• D, capture of CO2 from the atmosphere while sugar cane
grows;
• E, emissions from sugar cane bagasse combustion in ethanol
production;
• F, emissions from bagasse combustion for electricity
generation;
FIG. 7. GHG emissions from corn ethanol production and
avoided CO2 emissions.
• G, emissions in ethanol combustion in cars;
• H, gross avoided emissions of the use of ethanol as a gasoline
substitute in a life cycle
analysis; and
• H�, gross avoided emissions of fossil fuel for electric
generation in the grid, which is re-
placed by electric energy sold by the distilleries using the
surplus of bagasse �and trash� after
their self-consumption in ethanol production.
As shown in Fig. 8, CO2 capture while sugar cane grows �D�
is equal to the CO2 emitted when
ethanol is burned in car engines �G� plus CO2 emission from
the burning of sugar cane before

harvesting �C�� plus emissions from bagasse combustion in
ethanol distillation �E� and in elec-
tricity generation �F� for ethanol production:
balance of CO2 capture by sugar cane: D = C� + E + F + G .
�3�
However, there are emissions in sugar cane and ethanol
production to be subtracted from the gross
avoided emission H + H� in such a way that
net avoided CO2 by sugar cane ethanol: N = H + H� − A − B −
C . �4�
In the production of ethanol from corn, the unbalanced emission
is A + B + C + E + F in Eq. �2�,
while for sugar cane ethanol it is A + B + C in Eq. �4�. So,
assuming that variables A, B, and C in
Eq. �2� are not too different, respectively, from A, B, and C in
Eq. �4�, it is clear that net avoided
CO2 from sugar cane ethanol is higher than net avoided CO2
from corn ethanol:
N�sugar cane� � N�corn� . �5�
To calculate the net avoided CO2 emissions, we must subtract,
from the gross avoided CO2
emissions due to the use of ethanol as fossil fuel substitute, the
emissions of CO2 from fossil fuels
used in the sugar cane and ethanol production process, as well
as other GHG emitted for the
production of sugar cane and ethanol.
We must also express the mass of each non-CO2 GHG in terms
of equivalent CO2 emissions.
For that end, we have used here the global warming power

�GWP� for each GHG as provided in
the IPCC 1995 Report, incorporated by the UN Climate
Convention as a kind of regulation for
FIG. 8. GHG emissions from sugar cane ethanol production and
avoided CO2 emissions.
033111 �2009�
policymakers and adopted in national inventories and by the
Clean Development Mechanism
�CDM�. The GWP figures have been evaluated by IPCC
reports according to the definition by
Lashof and Ahuja.25 This definition provides the relative effect
of each GHG in thermal radiation
forcing on Earth’s surface using CO2 as a reference: GWP
�CO2� = 1. However, it does not repre-
sent the relative effect of each GHG in global temperature
increase due to anthropogenic GHG.12
Therefore, 1 kg of gas X corresponds to GWP�X , T� kg
equivalent of CO2, where T indicates the
period of time for which the GWP is calculated �usually, T =
100 years�.
There is in the literature a range of values for emissions in
sugar cane production �it is usual
to express alternatively the emission in terms of mass of carbon
in the molecule; for instance, the
mass of C in CO2 is 12 / �12 + 2 � 16� = 12 / 44 of the CO2
mass and the mass of C in CH4 is
12 / �12 + 4 � 1� = 12 / 16 of the CH4 mass� and for avoided
CO2 depending on the case and on the

methodology used. For instance, different papers consider
alternatively the following:
�a� the best situation, a particular case or the average of a set
of farmers and distilleries over a
period of time;
�b� either only the gross avoided emission H from the use of
ethanol as a gasoline substitute or
the gross avoided emission H + H�, including the gross avoided
emission H� of fossil fuel for
electric generation in the grid;
�c� either only the direct EC or the life cycle analysis,
including emissions in ethanol production
and in gasoline production to calculate H; and
�d� hydrated ethanol, anhydrous ethanol, or a mix of them in
the market.
Sometimes it is not clear which of the possible alternatives was
chosen, generating confusion in
quotations.
B. Numerical results from field research data on sugar cane
ethanol
A detailed life cycle analysis was presented in a report funded
by the Secretary of Environ-
ment of the State of São Paulo.26 The report was based on three
surveys, the first one covering
26–31 distilleries, the second one 17–22, and the third one
including a larger set of 98 distilleries
all over the country. Using this report as a reference, it is
possible to calculate representative
values for emissions from sugar cane and ethanol production in

percentages of CO2 equivalent
�Table III�.
The GHG emissions in sugar cane and ethanol production and
the CO2 that is avoided by
ethanol �kg CO2 equivalent / m3 of ethanol� are presented in
Table IV. The calculation of the
figures in Table IV deserves a detailed technical explanation.
The lower heat value of ethanol is
compensated by higher compression rate and better efficiency of
the engine. In the use of anhy-
drous ethanol as a gasoline additive, in a 25% proportion in
Brazil �E25�, 1 l of ethanol corre-
sponds to 1 l of gasoline. In the case of hydrated ethanol, the
proportion is 1.3 l of ethanol �E100�
TABLE III. GHG emissions in sugar cane ethanol production
�percentages of CO2 equivalent�. Based on data from Ref.
26.
Source of emission Kind of emission Percentage
From life cycle �A�: equipment, buildings, etc. In sugar cane
production 6.6
In ethanol production 9.5
From fertilizers, etc. �B� In sugar cane production 20.6
From burning sugar cane before harvest �C� CH4 19.1
N2O 18.2
From soil �C� N2O 6.9
From fossil fuel consumption �C� CO2 19.1
Adding up �according to Fig. 10� A 16.1
B 20.6
C 63.3

to 1 l of E25, which means 1 l of ethanol for 0.77 l of E25 or
0.77 � 0.75 = 0.577 l of gasoline. The
direct emission factor of gasoline is 0.0693 kg CO2 / MJ.
27 but in life cycle it becomes
0.0817 kg CO2 / MJ.
28 Using the above data, it is possible to calculate the net
avoided CO2 in
terms of percentage of fossil fuel CO2 emissions:
P = 1 − �A + B + C�/�H + H�� . �6�
The results are presented in Table IV as follows:
Average Best value
Percentage of avoided CO2
For anhydrous ethanol 86.5% 88.2%
For hydrated ethanol 80.7% 84.1%
Instead of the hypothesis of the use of bagasse as a substitute
for fuel oil to calculate H�, the
emissions from electric power generation in Brazilian
interconnected grid established for the CDM
can be applied. More recent data on the average emissions can
be obtained from Macedo et al.,3
considering the 2005/2006 harvest. Their case study focused on
a set of Brazilian distilleries that
process 100 Mton of sugar cane per year. The results are as

follows:
�a� For sugar cane and ethanol production, the total GHG
emissions using GWP �Ref. 29� are
A + B + C = 436 kg CO2 equivalent / m3 of ethanol.
�b� The net CO2 avoided emissions N = H + H� − �A + B +
C� = 2323 kg CO2 / m3 of
anhydrous ethanol �formula �4��.
�c� Applying formula �6�, the percentage of fossil fuel CO2
emission avoided due to anhydrous
ethanol is P = 84.1%.
The results above, although smaller than those of Table IV,
confirm that a very high percentage of
GHG emission is avoided by the use of sugar cane ethanol as a
substitute for gasoline.
We have estimated below the difference between the
percentages of avoided CO2 emission by
TABLE IV. Energy gain, GHG emissions, and percentage of
CO2 that is avoided by the ethanol industry in Brazil. Based
on data extracted from Ref. 26.
Results from 2002/2003 harvest Average Best value scenario
EC �Mcal/ton sugar cane�
Sugar cane 48.2 45.8
Ethanol production 11.8 9.5
Total 60.0 55.3
EP �Mcal/ton sugar cane� �ethanol + electric energy from

bagasse surplus� 499.4 565.7
Energy gain �EP/EC� 8.3 10.2
GHG emissions �kg CO2 equivalent/ton cane�
From fossil fuel consumption 19.2 17.7
Others 15.3 15.3
Total 34.5 33.0
Total GHG emission �kg CO2 equivalent / m3 of ethanol�
�A + B + C in Fig. 10� 405.8 358.7
Net avoided CO2 �kg CO2 / m3 of ethanol� from gasoline
and fuel oil for electric energy
N = H + H� − �A + B + C� in Fig. 8
For anhydrous ethanol 2600 2700
For hydrated ethanol 1700 1900
033111 �2009�
sugar cane ethanol and by corn ethanol, predicted by inequality
�5�. In the hypothesis of burning
fossil fuel for EC at the distillery, as in the case of corn
ethanol, the percentage P should be
calculated by
P = 1 − �A + B + C + E + F�/H . �7�
In Brazil, nearly 1 ton of bagasse is consumed to produce 2 m3
of ethanol,30 which means
about 20 900 MJ / m3. Assuming that this value is the self-
consumption of energy at the distillery

�from bagasse combustion� and that, instead of bagasse,
natural gas is burned, whose emission in
life cycle is 0.095 kg CO2 equivalent / MJ,
28 E + F = 20 900 � 0.095 = 1985 kg CO2 equivalent,
and using formula �7�, for a first approximation, the
percentage of GHG emission that is avoided
is reduced to P = 12%.
The above calculation simulates the percentage of CO2 that is
avoided in case fossil fuel is
burned to produce ethanol. This is what occurs for the
production of corn ethanol �Fig. 7�. Even
though emissions factors A, B, and C in ethanol production are
not the same for corn and sugar
cane as raw material, this figure makes it clear that the
percentage of CO2 that is avoided by corn
ethanol is lower than that of sugar cane ethanol. If P is doubled,
its value will nonetheless be small
�24%�. Actually, the value of P for corn ethanol can be a little
bit higher depending on the
efficiency of energy transformation in corn ethanol production.
C. Potential of energy efficiency and harvest mechanization for
avoiding GHG
1. Potential to improve the energy gain from ethanol, bagasse,
and trash
The energy balance of sugar cane ethanol can be improved by
�a� increasing sugar cane productivity in tons of sugar cane
per hectare,
�b� increasing the amount of ethanol produced from each ton
of sugar cane,
�c� using more trash, which means increasing mechanization

to reduce sugar cane burning
before harvesting, and
�d� improving efficiency in bagasse and trash energy
transformation in heat and in mechanical
and electric energies.
The sugar cane productivity went up from 2024 l per hectare in
1975 to 5931 l per hectare in
2005.31 The production in the 1975–2006 period increased from
89 � 106 metric tons to 426
� 106 metric tons.32 The results for recent years are shown in
Table V.
55% of sugar cane was used for producing 17.7 Mm3 of ethanol
in 2006, that is, 233 Mton
with 75.7 l/ton of sugar cane. In 2007/2008, the production is
20.3 Mm3 of ethanol and the
forecast for 2008/2009 is 24 Mm3, from which 58% of sugar
cane will be for used for ethanol
production.33 The best value is 92 l/ton of sugar cane.33
Should a change in the national average
in 2006 occur, reaching the best value above, there should be a
21% increase. It is expected that
CO2 saving H �formula �6�� through the use of ethanol as a
substitute for gasoline could increase
in the same proportion.
The energy generated from bagasse and trash �top and leaves�
is quite significant. Each ton of
sugar cane has 280 kg of bagasse with 50% of humidity and
2130 kcal/kg,30 providing 596 Mcal
per ton of sugar cane. Assuming the same average value for
trash, the energy of bagasse and trash
is more than double that of ethanol energy �Table VI�

calculated with 92 l with 0.8 kg/l and heat
value of 6500 kcal/kg.30
TABLE V. Sugar cane and ethanol production and productivity.
Source: Ref. 33.
Year
Processed cane
�Mton�
Ethanol
�Mm3�
Productivity
�l/ton�
2003 359.3 14.5 74.8
2006 426.0 17.7 75.7
In 2006, the bagasse production reached 121.0 Mton: 71.5 Mton
�59.1%� for sugar production,
42.0 Mton �34.7%� for ethanol production, and 7.5 Mton
�6.2%� for electric power, part of it to the
grid.30 Trash is not computed. Therefore, 94% of bagasse is
used to make heat and mechanical
work for sugar and ethanol production. If there is a reduction of
20% in this percentage through
efficiency improvement, the energy of bagasse available for
electric power increases by a factor of
0.25 / 0.062 = 4.

Besides, if 50% of trash is used, thermal energy for electric
generation will increase by a
factor of 0.75 / 0.062 = 12. Nowadays only a small part of
electric energy from bagasse is sold to
the grid, the avoided GHG emission H� due to electric energy
sale to the grid will be multiplied
by a factor of more than 12.
If H� goes up, the amount of CO2 avoided will be higher than
the amount avoided from the
use of ethanol as a gasoline substitute. The percentage P� of
avoided CO2 using H as basis, instead
of H + H�, in the denominator of Eq. �6�, is given by the
following formula:
P� = 1 − �A + B + C − H��/H . �8�
By comparing Eq. �8� with Eq. �7�, it is clear that the
additive term E + F �emissions from fossil
fuel consumption in corn ethanol� is replaced in the numerator
by a subtractive term H� �emission
avoided by fossil fuel saving in electric power generation to the
grid by sugar cane bagasse
surplus�.
It is clear that, if H� � A + B + C in Eq. �8�, P� � 1. The
electric installed capacity using bagasse
in 2006 was 2.6 GW,30 85% �2.2 GW� of which were for self-
consumption and 15% �only 0.4
GW� were sold to the grid. In that same year, 8357 GW h were
produced from sugar cane bagasse,
from which 1256 GW h to the grid.30 In the hypothesis of
increasing the electric power generation
from bagasse by a factor of 4, as pointed above, the installed
capacity could become 10.4 GW and
10.4 − 2.2 = 8.2 GW could be sold to the grid, 20 times the

current value of 0.4 GW.
So, the electric energy from bagasse to the grid in 2006 could
grow by a factor of 20,
becoming 25 120 GW h. Assuming that natural gas will be
replaced, with a life cycle emission of
0.095 kg CO2/MJ �Ref. 28� and 40% of efficiency, the
avoided CO2 calculation gives 2.13
� 109 kg of CO2. Once for that year the production of ethanol
was 17.7 Mm
3, the avoided CO2
could be 1200 kg CO2 / m3 of ethanol. The bagasse computed
for electric generation in the es-
timate above did come from ethanol and sugar production
because this industry is integrated.
Considering that 55% of sugar cane is used for ethanol
production, H�
= 660 kg CO2 / m3 of ethanol. Using this figure in formula
�8�, as well as the average values in
Table IV, the result is P� = 1.10, that is, 110%. Therefore, as
well as balancing the full emissions
of sugar cane and ethanol production, for each ton of CO2
avoided through the use of ethanol as
a substitute for gasoline, more 100 kg of CO2 could be avoided
due to the use of bagasse surplus
for electric power.
In 2007, bagasse used for electric power was 8.1 Mton,17 and
the installed capacity was 2.8
GW. However, direct sale of electric energy from bagasse in
2007 was about 25% of the installed
capacity,34 that is, 0.7 GW. In 2008, a bid for electric power in
the grid added 2.2 GW of installed
capacity using bagasse, and operations should start in the
coming years.15 The power predicted by

the bid, added to that realized in 2007, totals 2.9 GW, 35% of
the potential of 8.2 GW, calculated
with the above assumptions and without major technological
changes.
TABLE VI. Energy from 1 Mton of sugar cane considering heat
values. Source: Ref. 24.
Mcal/ton of cane
92 l of ethanol �best value� 478
280 kg of bagasse with 50% of humidity 596
280 kg of trash with 50% of humidity 596
033111 �2009�
2. Scenario for energy per ton of sugar cane and avoided GHG
by mechanization
Focusing only on ethanol production and referring to Table V
and to Ref. 21, bagasse con-
sumption for heat and mechanical work in ethanol production
amounts to 42 � 2130 / �426
� 0.55� = 382 Mcal / ton of sugar cane. Subtracting this value
from 596 Mcal �Table V�, 214 Mcal
of bagasse per ton of sugar cane in ethanol production can be
used for electric energy. By the same
token, 68.2 Mcal of bagasse per ton of sugar cane were used for
electric power generation in 2006.
Considering the use of 1 l of ethanol �average of hydrated and
anhydrous� instead of 0.79 l of
gasoline, with heat value of 10 400 kcal/kg and density of 0.74

kg/l, the correspondent energy is
0.79 � 0.74 � 10 400 = 6080 kcal per liter of ethanol or 75.7 �
6080 = 460 000 kcal / ton of sugar
cane. In the case of 92 l/ton of sugar cane, the equivalent
energy will be 559 Mcal /ton of sugar
cane.
However, trash recovering is limited because trash is also used
to protect and fertilize the soil
and because mechanization to avoid cane burning cannot be
used in more than 50% of the area
with the available technology due to declivity. On the other
hand, the burning of bagasse and trash
could be done with improved thermodynamic efficiency. Based
on such considerations, we were
able to build a future scenario, presented in Table VII, as
compared to 2006.
The scenario of Table VII does not take into account potential
improvements of efficiency in
energy transformation that could increase bagasse surplus, for
instance, by changing low-
efficiency steam systems for electric power. In many cases, low
pressure steam is used.
It is reasonable to get more mechanical and electric energy per
ton of sugar cane with higher
efficiency by decreasing bagasse self-consumption. As a rule,
22 bars of steam pressure are used,
which can be increased to 60 or 80 bars, improving efficiency
by a factor of 2. The self-
consumption of bagasse in ethanol production in some cases is
90% for heat in distillation of
ethanol, 5% for mechanical work, and 5% for electric power. If
efficiency is improved in the
conversion of heat in mechanical and electric energy, the

surplus of bagasse will be higher and
there will be more electric power to the grid per ton of bagasse.
Therefore, H� could be higher
again.
The mechanization of harvesting, used in such a way to avoid
the burning of sugar cane will
allow not only a higher value for H� due to the use of trash in
electric power generation but also
a lower value of emission C in Eq. �6� or Eq. �8�. However,
because of the slopes on part of the
lands used for sugar cane plantations, it is impossible to reach
100% of mechanization. If mecha-
nization is increased by 50% in relation to the case study
presented in Table III, there could be a
reduction of 0.5 � 37.3% = 18.6% in CO2 equivalent emission
of CH4 and N2O from the burning of
sugar cane.
On the other hand, the use of 50% more harvesting equipment
will increase emissions from
diesel oil in the same proportion. Assuming that half of fossil
fuel consumption in Table III is
diesel oil, the correspondent emission that represents 0.5 �
.19.1% = 9.5% will increase by 0.5
� 9.5 = 4.75%. The net result should be an emission reduction
of 18.6 − 4.75 = 13.85%. Diesel oil
TABLE VII. Energy from 1 Mton of sugar cane.
Mcal per ton of cane
Brazil 2006 Future scenario Variation
Ethanol �energy of gasoline replaced� 460a 559b 21%
Bagasse for electric energy �partly to grid� 68 214c 314%

Trash for electric energy �entirely to grid� 298d Infinite
Total 528 1071 102%
aConsidering 75.7 l of ethanol per ton of sugar cane �Brazilian
average in 2006�.
bWith the best value of 92 l of ethanol per ton of sugar cane.
cSelf-consumption of 377 Mcal /ton of sugar cane subtracted.
d50% of total mass.
can be eliminated by fueling diesel engines with either biodiesel
or ethanol with additive. The
variation of indirect energy in life cycle of harvesting
equipment �variable A in Table III� is not
considered in this approximation.
The problem of increasing the mechanization of harvesting is
the resulting reduction in work-
ers in sugar cane plantations. In 2005, there were 414 000
workers in sugar cane agriculture,
439 000 in sugar production, and 128 000 in the ethanol
industry.35 However, manual harvesting
of sugar cane is a very hard job that may cause diseases by
physical stress. Besides, the burning
of sugar cane causes air pollution, which, in turn, is a factor for
respiratory conditions for the local
population.
VI. DISCUSSION ABOUT LAND USE, ETHANOL
COMPETITION WITH FOOD, AND
DEFORESTATION

A. Land uses and deforestation
The issue of food crop displacement due to biofuel competition
was raised recently by Far-
gione et al.4 The paper shows that land use for biofuel increases
GHG in atmosphere due to
emissions from land use change in the US. The authors used a
model for estimating the planted
area due to biofuel production.
This problem is not new in Brazil. The displacement of food
crops by sugar cane in São Paulo
was pointed out a long time ago by Homem de Mello.36,37 In
fact, there is indeed displacement of
food crops, but its dimensions are very different in the case of
sugar cane in Brazil and in corn in
the US �Table VIII�. The US share in world corn production is
higher than the share of Brazil in
global sugar cane production, while the area used for corn
production in the US is five times the
area for sugar cane production in Brazil.
The area used for sugar cane production in Brazil is 7 � 106
ha—about 45% for sugar and
55% for ethanol—which means that about 4 � 106 ha are used
to produce ethanol. For comparison
purposes, soy bean uses 21 � 106 ha and cattle pastures occupy
177 � 106 ha. According to data
from the Brazilian Institute of Geography and Statistics,16 the
country has 152 Mha useful for
agricultural purposes. Therefore, sugar cane for ethanol
production uses only 2.6% of the area
useful for agriculture, without taking into account the recovery
of pasture lands that are being
degraded.

According to this same source, only 62 Mha are used for food
crops, biofuels, and other crops.
Therefore, there are 90 Mha available for the expansion of
agriculture without deforestation.
The Brazilian area of native vegetation is 440 Mha; most of it is
located in the Amazonian rain
forest, in the north region of the country. The production of
sugar cane is concentrated in the
southeast, mainly in São Paulo, followed by the middle west
region, with some contributions from
the south and northeast regions, but only 0.3% from the north
region, where the Amazon is located
�see Table IX�. The present impact of sugar cane for ethanol
on deforestation is low, as compared
to soybean for the external and internal markets, which includes
biodiesel production.
Two points should be noted about biofuels and deforestation:
TABLE VIII. Corn in the US � Sugar cane in Brazil. Source:
Refs. 16, 32, and 38.
US corn Brazil sugar cane
Percentage of world production �%� 54 33
Area occupied �Mha� 35 7
TABLE IX. Ethanol production in Brazil per region. Source:
Ref. 39.
Southeast: 72% Northeast: 7%
Middle West: 13% North: 0.3%
South:�7.7%

033111 �2009�
�a� The presence of sugar cane in the middle west region
�13%� impacts the savanna in the
Brazilian Cerrado, although this kind of vegetation is less dense
than rain forest.
�b� The situation of soybean, mainly for exportation but used
also for biodiesel, is different
because its presence in the north region is high, although
biodiesel production in Brazil is
relatively small in comparison with ethanol production.
One of the goals of the Biodiesel Program was the use of castor
oil, palm oil, sunflower, and
other raw materials produced by small farmers. However, the
present situation is the dominance of
large soybean plantations supplying vegetable oil for biodiesel.
The drivers of deforestation are 4, mainly in the rain forest:
�a� wood extraction,
�b� cattle pasture,
�c� soybean plantations, and
�d� mineral resources exploration.
There are different ways of calculating deforested areas
depending on whether or not reforested
areas are considered because they were deforested areas at some
point. In some studies, the
deforested areas considered are only the ones that really
changed land use definitely, as in the case
of agriculture or pasture. In other studies, the accidental

burning of biomass is considered defor-
estation. Another issue that can result in different figures is the
vegetal classification used in the
calculation of carbon emissions, as biomass density can be quite
different.
B. Potential sugar cane expansion and the external market
The next issue concerning possible impacts of the potential
expansion of sugar cane produc-
tion is related to ethanol exports as a substitute for gasoline in
OECD countries. The European car
fleet features a growing proportion of diesel engines, although
there is a non-negligible consump-
tion of gasoline either with or without ethanol as additive. Part
of the car fleet of Sweden uses a
blend of 80% ethanol and 20% gasoline �E80�.
Table X shows the countries with more significant ethanol
production as well as the countries
to which Brazil exports. Only the US and Brazil use ethanol as
gasoline substitute in a large scale.
In 2006, the US ranked first place in ethanol production,
followed by Brazil. However, the
percentage of ethanol blended to gasoline is very low in the US
because gasoline consumption is
very high, which makes the US the largest importer of ethanol
from Brazil. Therefore, the most
important potential market for Brazilian ethanol is the American
market, where Otto cycle engines
are predominant in the car fleet. There are other potential
importers, such as Japan, where Petro-
bras created a joint venture with Mitsubishi to export ethanol.
China also uses corn to produce
ethanol for cars. In 2006, there were 310 ethanol distilleries in
Brazil, and 77 new plants were

planned, with investments of over US$14 billions.32 Foreign
investors are being attracted to
ethanol agrobusiness in Brazil.
TABLE X. Ethanol in 2006. Source: Ref. 40.
Production Volume of Brazilian exports
USA 18 378 � 106 l EUA 1749 � 106 l
Brazil 17 000 Netherlands 344
China 3 850 Japan 228
India 1 900 Sweden 201
France 950 El Salvador 183
Germany 765 Jamaica 133
Russia 647 Venezuela 103
Canada 579
Spain 462
South Africa 386 Total 3 417 � 106 l
Presently, the North American market is not open to Brazilian
ethanol. However, in spite of
the weak result of international trade negotiations at
multilateral level to open it, there are some
reasons to believe that the present situation in the US will
change, including
�a� the inefficacy of corn ethanol to mitigate global warming
�see Sec. V above�,
�b� the higher competition of corn ethanol with food
agriculture �see this section�,
�c� the lower productivity per hectare and higher cost of corn

ethanol �see Table XI�, and
�d� the prediction of increasing the percentage of ethanol to
20% of car fuel �see scenario
below�.
Based on that, it is reasonable to develop a scenario for future
ethanol demand to be supplied
through international trade. The gasoline consumption in the US
is about 10 � 106 barrels / day.
Considering the hypothesis in �d�, with 20% of ethanol and
1.3 l of ethanol for 1 l of gasoline, the
future demand will reach 140 � 109 l of ethanol/year, seven
times the current Brazilian ethanol
production.
The necessary land area, with the same technology and average
productivity, should be mul-
tiplied by 7, resulting in 28 Mha for sugar cane, 30.4% of the
land available for the expansion of
agriculture in Brazil. This percentage is not small if we consider
the need of land for food
production and other crops, including biofuels, for the internal
market and for export to other
countries besides the US. If this demand is doubled, in order to
supply European countries and
Japan, the area needed for sugar cane would reach 56 Mha,
which is too large indeed. Besides,
there are the problems of a very large monoculture. Second
generation technology for ethanol
production must change the present prospects.
VII. FINAL COMMENTS
The conclusion is that there is no major obstacle, from the land
use point of view, to expand

ethanol production for the internal market. However, Brazil
should not supply the entire potential
market for ethanol in the world if ethanol use becomes a way
for global warming mitigation in a
large scale.
A more realistic projection indicates a production of about 36 �
109 l of ethanol in 2012, from
which 7 � 109 l are to be exported.32 Another scenario predicts
60 � 109 l of ethanol in 2020 with
12 � 109 l for export.42 Brazil can supply such quantities as
long as the areas needed are compat-
ible with the available lands for agriculture.
As was previously pointed out, CO2 is dominant among GHG
emissions and the automotive
fleet contributes with 20% of world CO2 emission. The
automotive fleet amounted to 890 � 10
6
light vehicles in 2005 and consumes half of the petroleum
products in the world.43 Besides, the
fleet increases by 20% per year in China and 3.5% in Brazil,
where 5.5 � 106 ethanol powered by
vehicles were produced since 1979, and 4 � 106 flex-fuel
vehicles produced since 2003 are run-
ning either on gasoline or on ethanol. Besides, ethanol is added
to gasoline in the proportion of
25%. Therefore, cars use from 25% to 100% of ethanol in
Brazil. CO2 emission avoided is
substantial.
However, ethanol itself is not enough to mitigate CO2 emissions
at world level. It is also
necessary, deep changes, in energy technology, transport

�including public transport�, and con-
sumption patterns that are still dependent on diesel engines. But
ethanol can become an important
fuel for different technologies, besides the Otto cycle engines in
cars. Combined to additives,
TABLE XI. A comparison of sugar cane ethanol with corn
ethanol. Source: Refs. 21 and 41.
Productivity
�l/ha� Costs
Sugar cane ethanol 4000–7000 0.19 US$/l �São Paulo�
0.23 US$/l �Northeast Brazil�
Corn ethanol 3500–4700 0.33 US$/l
033111 �2009�
ethanol could power diesel engines used in buses, trucks, and
railway locomotives. It can be used
as fuel for hybrid vehicles of electrical propulsion—in which
the Otto or diesel engine is coupled
to an electric power generator that supplies current for an
electrical motor and for accumulating
energy in batteries—or in fuel cell vehicles to replace
combustion engine to supply current for an
electrical motor.
Sugar cane is the best way to produce bioethanol from both the
economical and the environ-
mental point of view, including GHG mitigation through the use
of ethanol as a gasoline substi-

tute. However, ethanol industry in Brazil must be improved,
including the adoption of technologi-
cal changes, some of them concerning efficiency in energy
transformation and natural resources
use. The main changes must be made at the first level:
�a� Improving efficiency in the transformation of chemical
energy of sugar cane bagasse in heat
for distillation and in mechanical and electric energy for self-
consumption and to sell energy
to the grid; today, the share of bagasse in electric generation in
Brazil is too small and must
be increased.
�b� Using the sugar cane trash, which is burned before
harvesting to facilitate the manual job of
workers; the amount of energy that could be obtained for
electric generation is significant.
�c� Item �b� implies the increase in harvesting
mechanization in sugar cane agriculture, decreas-
ing the number of workers, but work conditions in manual
harvesting are harsh.
�d� Improving conditions of workers in sugar cane plantations
in some cases, including both the
social and the environmental dimension in clean energy
production �EP�.
�e� Improving technology both in agriculture and in the
industry.
At the second level:
�a� gasification of sugar cane bagasse and trash,

�b� second generation ethanol production through hydrolysis,
and
�c� biorefineries with multiple by-products or integrated oil
and biorefineries in a more advanced
concept.
Gasification could either allow high-efficiency conversion into
electric energy through com-
bined cycle or could be used to produce liquid fuel from gas.
Second generation ethanol is
hydrolysis acidic or enzymatic, followed by fermentation, that
leads to the conversion of biomass
fiber �lignin and cellulose� into ethanol.
The commercial use of hydrolysis can reduce sugar cane
comparative advantage as compared
to other kinds of vegetable used to produce ethanol. On the
other hand, the entire mass of sugar
cane could be used to obtain ethanol, including the hydrolysis
of bagasse and trash, as well as
allows the fermentation of pentose to produce ethanol.
Macedo32 predicted a time horizon between
2010 and 2020 for second generation ethanol to become
commercial, while for gasification this
time is a little bit longer, 2015–2025, in spite of the already
existing technological uses of wood
gasification. In the case of hydrolysis, there are prototypes, and
some recent small scale industrial
plants are being built around the world for ethanol production,
although not yet commercial.
Biorefineries can produce ethanol together with other chemical
by-products. For instance,
biodiesel production needs ethanol or methanol and uses
glycerol as a by-product that can be used

to produce gasoline. Since the beginning, ethanol production in
Brazil was integrated to sugar
production in the so-called annex distilleries. A more advanced
concept is the integration of
biorefineries with oil refineries, as, for instance, does the H-bio
technology developed by Petrobras
�Table II� parallel to biodiesel from vegetable oil. Although
this is out of the scope of this paper,
biodiesel production must be improved in many aspects that are
not dealt with here.
Finally, biofuels for private cars must not drop the issue of
technical and social efficiencies in
transportation nor the encouragement to improve public
transportation. A Climate Change policy
must find realistic solutions for sustainable development with
social justice. The elimination of
poverty requires more power per capita in developing countries;
however, at the same time,
intensive energy use is necessary and the consumption patterns
of the high income and middle
classes must be changed. It is not possible to deeply mitigate
global warming without making
changes in business as usual EC.
LIST OF ABBREVIATIONS AND ACRONYMS
CDM Clean Development Mechanism
CO2 Carbon dioxide
CO2 equivalent Carbon dioxide equivalent
COPPE Instituto Alberto Luiz Coimbra de Pós-Graduação e

Pesquisa de Engenharia
of Federal University of Rio de Janeiro
E25 Ethanol 25%
GHG greenhouse gas
GJ Gigajoules �109�
GW Gigawatts �109�
GW h Gigawatts hour �109�
GWP Global warming potential
IPCC International Panel on Climate Change
kcal kilocalories �103�
kg kilogram
m3 cubic meters
Mcal Megacalories �106�
Mha Megahectare �106�
MJ Megajoules �106�
Mm3 Mega-cubic-meters �106�
Mton Megatons �106�
Mtoe Megatons of oil equivalent
OECD Organisation for Economic Co-operation and
Development
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