Integrated 1st & 2nd Generation Bioethanol Production from Sugarcane
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This document discusses biofuels production from sugarcane bagasse. It describes the multi-step process of producing ethanol from bagasse, including pretreatment, hydrolysis, fermentation and distillation. The process yields 4.23 liters of fuel ethanol from 70 kg of sugarcane bagasse starting material. Additionally, the document outlines the economics of bagasse bioethanol, noting its potential to be a competitive energy source. Issues related to the environmental and social impacts of sugarcane production are also briefly discussed.
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Integrated 1st & 2nd Generation Bioethanol Production from Sugarcane
2. Introduction
Biofuels are a wide range of fuels which are in some
way derived from biomass.
Different generations of biofuel according to source:
GENERATIONS FEEDSTOCK
First Sugarcane, grains and seeds -as soya
bean ,sorghum, corn etc
Second Agricultural residues such as
Sugarcane bagasse, corn straw and
industrial waste.
Third Algae
3. Biofuels vs Fossil fuels
Fossils are depleting and
biofuels are used to
complement them.
Biofuels are carbon
neutral.
Cars are compatible with
Fossil fuels.
Fossil fuel readily
available.
5. Bagasse:
Fibrous matter that remains
after sugarcane stalks are
crushed to extract their juice.
Production: Each 10 tons of
sugarcane = 3 tonnes of wet
bagasse. Source: ceesdghana.org
Quantity of bagasse produced = size of sugarcane industry.
Chemical analysis: Cellulose 45-55%,
hemicellulose 20-25%, lignin 18-24%, ash 1-4%, waxes <1%.
6. First Generation Process
SUGAR JUICE
SUGARCANE CLEANING
EXTRACTION TREATMENT
SUGARCANE JUICE
BAGASSE CONCENTRATION
DEHYDRATION DISTILLATION CENTRIFUGATION FERMENTATION
‘SOILDS’
ANHYDROUS INTEGRATION
ETHANOL OF 2nd
GENERATION
SUGARS
7. Detoxification To purification
Alkaline neutralisation detoxification Ethanol , waste mixture
Bagasse
-Lignin (30%) Overliming
-Cellulose (40%) -Calcium hydroxide
-Hemicellulose (30%) -4hrs
-300C Hexose and Pentose
Fermentation
Removes 50% of waste – precipitates out
Liquid fraction – -Hydroxymethylfurfural Co-fermentation
Degraded hemicellulose -aliphatic acid
Pentose sugars – primarily xylose Yeast - Hexose
-phenolic compounds Recombinant yeast – Pentose
-pentose metabolism
Yield = 60% pentose (xylose) pathways
Pretreatment
-360C
Pretreatment separates lignin -24hrs
and hemicellulose, reduces Filtration -1- part yeast
cellulose crystallinity and Separates solid and -4-parts reducing sugar
increases porosity liquid fraction mixture
-5-parts nutrient broth
-Dilute HCl
-HCl conc. = 1.2% v/v Yield = 80% ethanol
-15 parts acid to 1 part bagasse
-1210C Solid fraction – Cellulose Hydrolysis Sugars used for cell
-4Hrs Cellulose maintenance
Lignin Degrade cellulose to Pentose metabolism has
-Yield = 38% - reducing sugars glucose (saccharification) reduced efficiency
in the form of hemicellulose
and cellulose -using conc. HCl -15% v/v
-1800C
-4hrs
-30Bars
Neutralises
Yield = 35% hexose -NaOH
(glucose) from solid
fraction
Second Generation Process Hexose (glucose) from
sugarcane – first generation
8. Detoxification To purification
Alkaline neutralisation detoxification Ethanol , waste mixture
Bagasse
100Kg of bagasse = Overliming
30Kg lignin
Yield = 60% pentose (xylose) 6.81Kg of ethanol
40Kg cellulose
10.64Kg of water
30Kg hemicellulose >2.128Kg of yeast
Total liquid = 17.45Kg
70Kg worth of reducing 4.79Kg of pentose (xylose)
sugars
30% hemicellulose
Hexose and Pentose
7.98Kg
Fermentation
Pretreatment
Co-fermentation
-Yield = 38% - reducing sugars 26.6Kg -1- part yeast – 2.128Kg
in the form of hemicellulose Filtration 4.79 + 3.72 = 8.51Kg of -4-parts reducing sugar
and cellulose Separates solid and reducing sugars mixture – 8.51Kg
liquid fraction -5-parts water suspension –
10.64Kg
Yield = 80% ethanol
40% Cellulose = 10.64Kg
30% Lignin = 30Kg (not
broken down)
Cellulose Hydrolysis 3.72Kg
Hexose
(glucose)
Degrade cellulose to
glucose (saccharification)
Yield = 35% hexose Neutralises
(glucose) from solid -NaOH
fraction
Second Generation Process: Hexose (glucose) from
Mass Balance sugarcane – first generation
9. Hybrid Purification
4.23L Ethanol
Yield 6.5% from 70Kg starting material
FUEL ETHANOL 99.5%
AZEOTROPE ETHANOL 65% (4.42L Ethanol)
AZEOTROPE ETHANOL 96% (4.24L Ethanol)
“Distillation 2” de
Dehydration
Supernatant Distillation
17.45L=
6.8L Ethanol
10.64L Waste
Supernatant
Water Water
Water
Centrifugation:
Lignin, Yeast
10. Dehydration Methods Used.
Lime (calcium oxide) or rock salt
Addition of an entrainer. Adding small quantities
of benzene or cyclohexane.
Molecular Sieves
Membranes :
Can not be exposed to high water concentration
Fouling by fusel oils
Pressure reduction
11. SiftekTM Membrane & System
Produced by Vasperma, gas separation solutions.
This system can be integrated in a bio-ethanol plant.
Replacing the 2nd distillation column and the
molecular sieve units for the dehydration process.
Potential of reducing energy consumption by up to
50%.
12. SiftekTM Membranes
Hydrophilic polymer membrane
Exceptional thermal mechanical and solvent resistance
properties
Membrane is a proprietary formulation based on
polyimide
Provides high flux and water/ethanol selectivity.
13. BY PRODUCTS
Vinasse:- Distillation step.
Biodigestion of vinasse-electric power.
1 m3 of bioethanol 115 m3 of biogas 169 kWh
of bioelectricity.
As fertilizers
Single cell protein production.
Non-structural bricks.
Animal feed.
Thermophilic digesters Biogas Vinasse methane.
14. Carbondioxide: Fermentation step
Washed to recover the bioethanol.
Carbonated beverages and dry ice, sodium bicarbonate
manufacturing and treatment of effluents.
760 kg of CO2 1000 L of anhydrous bioethanol.
Fusel oil : Distillation step
Alcohol components acetic acid and butyric acid esters.
Flavour and fragrance manufacturing.
Ethylbutyrate is used as pineapple-banana flavours in the food
industry.
15. Second class ethanol:
This type is used in Pharma, cosmetics and food industry.
Lignin:
Wood adhesive.
Emulsions and dispersants.
Carbon fibre precursor.
Other products:
Bagasse -Bioelectricity: cogeneration system.
One ton of sugarcane - 250 kg of bagasse -500 kg to 600 kg
of steam -electric power production.
16. Economics of bagasse bioethanol fuel:
Potential to be competitive energy resource but needs
favourable policies.
Does not compete with food production
Cheaper compared to food crops (price per ton)
Reduce solid waste disposal costs.
Cellulosic ethanol is US$0.59/litre. At this price, it will
cost US$120 to substitute a barrel of oil (159 L).
19. Production costs:
Comparison of the production costs (€/1000 liters) of ethanol in Brazil, United States and Germany.
Source: Goldemberg 2008
20. Commercialization
Refineries are been built by companies like Iogen, Abengoa and Broin while
companies like Novozymes, Diversa and Dyadic are producing enzymes
which will enhance cellulosic ethanol future.
Fuel Ethanol Production by Country(Millions of U.S. liquid gal/yr)
Country/Region 2009 2008 2007
United States 10,750.00 9,000.00 6,498.60
Brazil 6,577.89 6,472.20 5,019.20
European Union
1,039.52 733.60 570.30
China 541.55 501.90 486.00
Thailand 435.20 89.80 79.20
Canada 290.59 237.70 211.30
India 91.67 66.00 52.80
Colombia 83.21 79.30 74.90
Australia 56.80 26.40 26.40
Other 247.27
World Total 19,534.99 17,335.29 13,101.70
Source: Wikipedia.org
21. Brazil: Ethanol - Transport sector
Year policy Results
1976 mandatory fluctuated between 10 -
25%
1993 mandatory 20% E20
2007 mandatory 25% E25
2003 Introduction Flex-Fuel vehicles
2008 E25-Flex vehicles 18% of Brazils total
energy consumption -
transport sector
2009 Flex-Fuel vehicles- 92.3% of share -SUCCESS
22. Issues: Environmental and Social Impacts of Sugarcane
Production
Deforestation
99.7% of sugarcane plantations are located at least
2,000 kilometres (1,200 mi) from the Amazonia
Fertilizer – water pollution
Effects on food prices
Bagassosis
23. Conclusion:
By integrating 1st & 2nd generation sugarcane ethanol fuel
production, we can simultaneously increase yield and
efficiency, whilst reducing costs and recycling co-
products.
Renewable energy source, which can be very competitive
with any other fuel source in terms of cost and efficiency.
Its benefits are unparalleled as it converts waste to
energy fuel which does not contest on food crops.
However, more research and development is necessary
for 2nd generation fuel production.
24. References:
Biomass- based energy fuel through biochemical routes: A
review (2007)
R.C. Saxena , D.K. Adhikari, H.B. Goyal.
Improving bioethanol production from sugarcane :
evaluation of distillation, thermal integration and
cogeneration systems (2010)
Marina O.S. Dias et al.
Membrane- Based Ethanol Dewatering System (2010)
Pierre Cote et al.
Editor's Notes
The purification step involves a distillation step and a dehydration step. Typically, 2 distillation columns are used. Distillation, only concentrates the ethanol to a certain extent. Another step has to be introduced to further purify the ethanol, a dehydration step. After distillation, what is produced is call an AZEOTROPE. Azeotrope is a water/ethanol mix