2. CONTENTS
I. What is bioethanol?
II. Bioethanol Production
III. Fuel Properties
IV. Application
V. Advantages
VI. Disadvantages and Concerns
VII.Ethanol Controversy
VIII.Comparison of Bioethanol and
Biodiesel
IX. Future development www.greencarreports.com
3. What is Bioethanol
Bioethanol is an alcohol made
by fermentation, mostly
from carbohydrates produced
in sugar or starch crops such
as corn or sugarcane. Cellulosic biomass,
derived from non-food sources such as trees
and grasses, is also being developed as
a feedstock for ethanol production
http://www.ecosmartfire.com/media/images/bio/what-is-ethanolmade-from.jpg
4. Contd.
The principle fuel used as a petrol substitute is bioethanol
Bioethanol fuel is mainly produced by the sugar or cellulose
fermentation process
Ethanol is a high octane fuel and has replaced
lead as an octane enhancer in petrol
Bioethanol is an alternative to gasoline for flexifuel
vehicles
5. Bioethanol Production
• Wheat/Grains/Corn/Sugar-cane can be used to
produce ethanol. (Basically, any plants that composed
largely of sugars)
• Bioethanol is mainly produced in three ways.
• Sugar
• starch
ethanol
sugar
• cellulose and hemicellulose
ethanol
ethanol
6. Bioethanol Production
•
Concentrated Acid Hydrolysis
–
–
–
–
–
~77% of sulfuric acid is added to the dried biomass
to a 10% moisture content.
Acid to be added in the ratio of 1/25 acid :1
biomass under 50°C.
Dilute the acid to ~30% with water and reheat the
mixture at100°C for an hour.
Gel will be produced and pressed to discharge the
acid sugar mixture.
Separate the acid & sugar mixture by using a
chromatographic column .
7. Bioethanol Production
• Dilute Acid Hydrolysis
–
–
–
–
oldest, simplest yet efficient method
hydrolyse the bio-mass to sucrose
hemi-cellulose undergo hydrolysis with the
addition of 7% of sulfuric acid under the
temperature 190°C.
to generate the more resistant cellulose
portion, 4% of sulfuric acid is added at the
temperature of 215°C
8. Bioethanol Production
• Wet milling process
– corn kernel is soaked in warm water
– proteins broken down
– starch present in the corn is released
(thus, softening the kernel for the milling process)
– microorganisms, fibre and starch products are
produced.
– In the distillation process, ethanol is produced.
9. Bioethanol Production
• Dry milling process
– Clean and break down the corn kernel into fine
particles
– Sugar solution is produced when the powder
mixture (corn germ/starch and fibre) is broken
down into sucrose by dilute acid or enzymes.
– Yeast is added to ferment the cooled mixture into
ethanol.
10. Bioethanol Production
• Sugar fermentation
– Hydrolysis process breaks down the biomass
cellulosic portion into sugar solutions which will
then be fermented into ethanol.
– Yeast is added and heated to the solution.
– Invertase acts as a catalyst and convert the sucrose
sugars into glucose and fructose. (both C6H12O6).
11. Bioethanol Production
Chemical reaction 1
The fructose and glucose sugars react with zymase
to produce ethanol and carbon dioxide.
Chemical reaction 2
Fermentation process requires 3 days to complete
and is carried out at a temperature of between
250°C and 300°C.
12. Bioethanol Production
• Fractional Distillation Process
– After the sugar fermentation process, the ethanol
still does contain a significant quantity of water
which have to be removed.
– In the distillation process, both the water and
ethanol mixture are boiled.
– Ethanol has a lower boiling point than water,
therefore ethanol will be converted into the vapour
state first condensed and separated from water.
13. Feedstocks
• Sugar is required to produce ethanol by
fermentation.
– Plant materials (grain, stems and leaves) are
composed mainly of sugars
– almost any plants can serve as feedstock for ethanol
manufacture
• Choice of raw material depends on several
factors
–
–
–
–
ease of processing of the various plants available
Crops used in Bioethanol production
prevailing conditions of climate
Brazil
sugar cane
landscape and soil composition
USA
corn
sugar content
India
sugar cane
Europe
wheat and barley
14. Feedstocks
• R&D activities on using lignocellulosic
(woody materials) as feedstock
– Lignocellulosic biomass is more abundant and
less expensive than food crops
– higher net energy balance
– accrue up to 90% in greenhouse gas savings,
much higher than the first generation of biofuel
– However, more difficult to convert to sugars due
to their relatively inaccessible molecular
structure
15. Conversion of starch to sugar and then
sugar to ethanol
Eg:-1) wheat
Fermentation conditions
Temperature - 32˚C and 35˚C
pH - 5.2.
Ethanol is produced at 10-15% concentration and the solution is distilled to
produce ethanol at higher concentrations
16. Eg:- 2) sugar cane
Simplest of all the processes
• Fermentation conditions are similar to the above process
17. Contd.
Ethanol can be produced from a variety of feedstocks such as
sugar cane, bagasse, sugar
beet, switchgrass, potatoes, fruit, molasses
corn, stover, wheat, straw, other biomass, as well as many types
of cellulose waste and harvestings
Agricultural feedstocks are considered renewable because
they get energy from the sun using photosynthesis
Cornfield in South
Africa
Sugar cane harvest
Switchgrass
18. Direct conversion of sugar to ethanol
• This is usually done using molasses.
• Molasses is a thick dark syrup produced by boiling down juice from
sugarcane; specially during sugar refining.
• As molasses is a by product, ethanol production from molasses is
not done in a large scale around the world.
The main reaction involved is fermentation
yeast
C6H12O6
2 C2H5OH
sugar (e.g.:-glucose)
ethanol
+
2 CO2
carbon dioxide
19. The top five ethanol producers in 2010
Brazil - 16500 billion liters
The United States -16270 billion liters
China - 2000 billion liters
The European Union - 950 billion
liters
India - 300 billion liters
21. Bioethanol Properties
Colourless and clear liquid
Used to substitute petrol fuel for road transport
vehicles
One of the widely used alternative automotive fuel in
the world (Brazil & U.S.A are the largest ethanol producers)
Much more environmentally friendly
Lower toxicity level
source :
southdakotapolitics.blogs.com
22. Fuel Properties
Fuel Properties
Gasoline
Molecular weight
111
[kg/kmol]
Density [kg/l] at 15⁰C 0.75
Bioethanol
46
Oxygen content [wt%]
Lower Calorific Value
[MJ/kg] at 15ºC
Lower Calorific Value
[MJ/l] at 15ºC
Octane number
(RON)
Octane number
(MON)
Cetane number
Stoichiometric
air/fuel ratio [kg air/kg
fuel]
Boiling temperature
[ºC]
Reid Vapour
Pressure [kPa] at
15ºC
34.8
0.80-0.82
41.3
26.4
31
21.2
97
109
86
92
8
14.7
11
9.0
30-190
78
75
16.5
• Energy content
– Bioethanol has much
lower energy content
than gasoline
– about two-third of
the energy content
of gasoline on a
volume base
23. Fuel Properties
Fuel Properties
Molecular weight
[kg/kmol]
Density [kg/l] at 15⁰C
Oxygen content [wt%]
Lower Calorific Value
[MJ/kg] at 15ºC
Lower Calorific Value
[MJ/l] at 15ºC
Octane number
(RON)
Octane number
(MON)
Cetane number
Stoichiometric
air/fuel ratio [kg air/kg
fuel]
Boiling temperature
[ºC]
Reid Vapour
Pressure [kPa] at
15ºC
Gasoline
111
Bioethanol
46
0.75
0.80-0.82
34.8
41.3
26.4
31
21.2
97
109
86
92
8
14.7
11
9.0
30-190
78
75
16.5
• Reid vapour pressure
(measure for the volatility
of a fuel)
– Very low for ethanol,
indicates a slow
evaporation
– Adv: the concentration of
evaporative emissions in
the air remains relatively
low, reduces the risk of
explosions
– Disadv: low vapour pressure
of ethanol -> Cold start
difficulties
– engines using ethanol
cannot be started at temp <
20ºC w/o aids
24. Fuel Properties
Fuel Properties
Gasoline
Molecular weight
111
[kg/kmol]
Density [kg/l] at 15⁰C 0.75
Bioethanol
46
Oxygen content [wt%]
Lower Calorific Value
[MJ/kg] at 15ºC
Lower Calorific Value
[MJ/l] at 15ºC
Octane number
(RON)
Octane number
(MON)
Cetane number
Stoichiometric
air/fuel ratio [kg air/kg
fuel]
Boiling temperature
[ºC]
Reid Vapour
Pressure [kPa] at
15ºC
34.8
0.80-0.82
41.3
26.4
31
21.2
97
109
86
92
8
14.7
11
9.0
30-190
78
75
16.5
• Octane number
– Octane number of ethanol
is higher than petrol
– hence ethanol has better
antiknock characteristics
– increases the fuel
efficiency of the engine
– oxygen content of ethanol
also leads to a higher
efficiency, which results in
a cleaner combustion
process at relatively low
temperatures
25. Application
•
•
•
•
•
transport fuel to replace gasoline
fuel for power generation by thermal combustion
fuel for fuel cells by thermochemical reaction
fuel in cogeneration systems
feedstock in the chemicals industry
http://us.123rf.com/400wm/400/400/freeha
ndz/freehandz1209/freehandz120900083/1
5300880-bioethanol--biomass-truck.jpg
26. Application
• Blending of ethanol with a small proportion of a
volatile fuel such as gasoline -> more cost effective
• Various mixture of bioethanol with gasoline or
diesel fuels
–
–
–
–
E5G to E26G (5-26% ethanol, 95-74% gasoline)
E85G (85% ethanol, 15% gasoline)
E15D (15% ethanol, 85% diesel)
E95D (95% ethanol, 5% water, with ignition improver)
27. Advantages
• Exhaust gases of ethanol are much cleaner
– it burns more cleanly as a result of more complete
combustion
• Greenhouse gases reduce
– ethanol-blended fuels such as E85 (85% ethanol and 15%
gasoline) reduce up to 37.1% of GHGs
• Positive energy balance, depending on the type of raw
stock
– output of energy during the production is more than
the input
• Any plant can be use for production of bioethanol
– it only has to contain sugar and starch
• Carbon neutral
– the CO2 released in the bioethanol production process
is the same amount as the one the crops previously
absorbed during photosynthesis
28. Advantages
• Decrease in ozone formation
– The emissions produced by burning ethanol are less reactive with
sunlight than those produced by burning gasoline, which results in a
lower potential for forming ozone
• Renewable energy resource
– result of conversion of the sun's energy into usable energy
– Photosynthesis -> feedstocks grow -> processed into ethanol
• Energy security
– esp. Countries that do not have access to crude oil resources
– grow crops for energy use and gain some economic freedom
• Reduces the amount of high-octane additives
• Fuel spills are more easily biodegraded or diluted
to non toxic concentrations
29. Disadvantages and Concerns
• Biodiversity
– A large amount of arable land is required to grow
crops, natural habitats would be destroyed
• Food vs. Fuel debate
– due to the lucrative prices of bioethanol some
farmers may sacrifice food crops for biofuel
production which will increase food prices around
the world
• Carbon emissions (controversial)
– During production of bioethanol, huge amount of
carbon dioxide is released
– Emission of GHGs from production of bioethanol is
comparable to the emissions of internalcombustion engines
30. Disadvantages and Concerns
• Not as efficient as petroleum
– energy content of the petrol is much higher than bioethanol
– its energy content is 70% of that of petrol
• Engines made for working on Bioethanol cannot be
used for petrol or diesel
– Due to high octane number of bioethanol, they can be
burned in the engines with much higher compression ratio
• Used of phosphorous and nitrogen in the
production
– negative effect on the environment
• Cold start difficulties
– pure ethanol is difficult to vaporise
31. Disadvantages and Concerns
• Transportation
– ethanol is hygroscopic, it absorbs water from the air and thus
has high corrosion aggressiveness
– Can only be transported by auto transport or railroad
• Many older cars unequipped to handle even 10%
ethanol
• Negatively affect electric fuel pumps by increasing
internal wear and undesirable spark generation
33. Is it justifiable?
..to use agriculture land to grow energy crops instead of food crops
when there are so many starving people in the world. In the
developed countries that is not a problem, but in the developing
ones where we have a large number of people living below the
poverty this may lead to a crisis.
34. Ethanol Controversy
• Is burning biofuel more environmentally friendly
than burning oil?
– Fact that producing biofuel is not a "green process“
– requires tractors and fertilisers and land
– With the increase in biofuel production, more forests will
be chopped down to make room for biofuel, ↑ CO2
• Better alternative suggested by scientists..
– steer away from biofuel and focus on reforestation and
maximising the efficiency of fossil fuels instead
35. Comparison of Bioethanol and Biodiesel
Bioethanol
Biodiesel
Process
Dry-mill method: yeast, sugars and
Transesterification: methyl esters and
starch are fermented. From starch, it is
glycerin which are not good for engines,
fermented into sugar, afterwards it is
are left behind.
fermented again into alcohol.
Environment Both reduce greenhouse gas emissions as biofuels are primarily derived from crops
al Benefit
which absorb carbon dioxide.
Compatibility ethanol has to be blended with fossil fuel Able to run in any diesel generated
like gasoline, hence only compatible
engines
with selected gasoline powered
automobiles.
Costs
Cheaper
More expensive
Gallons per
420 gallons of ethanol can be generated 60 gallons of biodiesel per acre
acre
per acre
soybeans
cost of soybean oil would significantly
increase if biodiesel production is
increased as well.
Energy
provides 93% more net energy per
produces only 25% more net energy.
gallon
Greenhouse- 12% less greenhouse gas emission than 41% less compared to conventional
gas
the production and combustion of
gasoline.
Emissions
regular diesel
(GHG)
36. Social impacts
– Created jobs for locals (mainly in rural areas)
– Brazilian sugarcane industry has a particularly
poor record in respecting worker’s rights
– Expansion in sugar cane cultivation may
increase food prices. This would leave the poor
with a harder survival.
– Although the ethanol industry has greatly
increased the wealth of the sugar and alcohol
sector’s industries, the poor have to be the one
handling the negative impacts.
37. Future development
• For bioethanol to become more sustainable to
replace petrol, production process has to be more
efficient
– Reducing cost of conversion
– Increasing yields
– Increase the diversity of crop used
• As microbes are use to convert glucose into sugar
which is ferment in bioethanol
– Microbiology and biotechnology will be helpful in the
genetic engineering
