Integrated 1st & 2nd Generation Bioethanol Production from

Sugarcane

Suman SwamiOnyedika Egbujo

Emmanuel OgbughaluDominic Smith

Priyesh Waghmare

IntroductionBiofuels 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

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.

Ethanol technicalities in Car Engines

Performance.

Cold start.

Mileage.

Sludge problem.

Corrosion.

Higher ethanol blends.

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.

Quantity of bagasse produced = size of sugarcane industry.

Chemical analysis: Cellulose 45-55%, hemicellulose 20-25%, lignin 18-24%, ash 1-4%, waxes <1%.

Source: ceesdghana.org

First Generation Process

SUGARCANE CLEANING SUGAR EXTRACTION

JUICE TREATMENT

JUICE CONCENTRATION

‘SOILDS’

FERMENTATIONCENTRIFUGATIONDISTILLATIONDEHYDRATION

ANHYDROUS ETHANOL

SUGARCANE BAGASSE

INTEGRATION OF 2nd GENERATION SUGARS

Pretreatment

Pretreatment separates lignin and hemicellulose, reduces cellulose crystallinity and increases porosity

-Dilute HCl -HCl conc. = 1.2% v/v-15 parts acid to 1 part bagasse -1210C -4Hrs

-Yield = 38% - reducing sugars in the form of hemicellulose and cellulose

DetoxificationAlkaline neutralisation detoxification

Overliming -Calcium hydroxide -4hrs -300C

Removes 50% of waste – precipitates out-Hydroxymethylfurfural-aliphatic acid-phenolic compounds

Yield = 60% pentose (xylose)

Cellulose Hydrolysis

Degrade cellulose to glucose (saccharification)

-using conc. HCl -15% v/v-1800C-4hrs-30Bars

Yield = 35% hexose (glucose) from solid fraction

Hexose and Pentose Fermentation

Co-fermentationYeast - HexoseRecombinant yeast – Pentose-pentose metabolism pathways

-360C-24hrs-1- part yeast-4-parts reducing sugar mixture-5-parts nutrient broth

Yield = 80% ethanol

Sugars used for cell maintenancePentose metabolism has reduced efficiency

Bagasse -Lignin (30%)-Cellulose (40%)-Hemicellulose (30%)

Filtration Separates solid and liquid fraction

Liquid fraction – Degraded hemicellulose Pentose sugars – primarily xylose

Solid fraction – CelluloseLignin

Neutralises-NaOH

Hexose (glucose) from sugarcane – first generation

To purificationEthanol , waste mixture

Second Generation Process

Pretreatment

-Yield = 38% - reducing sugars in the form of hemicellulose and cellulose

DetoxificationAlkaline neutralisation detoxification

Overliming

Yield = 60% pentose (xylose)

Cellulose Hydrolysis

Degrade cellulose to glucose (saccharification)

Yield = 35% hexose (glucose) from solid fraction

Hexose and Pentose Fermentation

Co-fermentation

-1- part yeast – 2.128Kg-4-parts reducing sugar mixture – 8.51Kg-5-parts water suspension – 10.64Kg

Yield = 80% ethanol

Bagasse 100Kg of bagasse =30Kg lignin40Kg cellulose30Kg hemicellulose

Filtration Separates solid and liquid fraction

Neutralises-NaOH

Hexose (glucose) from sugarcane – first generation

To purificationEthanol , waste mixture

70Kg worth of reducing sugars

26.6Kg

30% hemicellulose 7.98Kg

40% Cellulose = 10.64Kg30% Lignin = 30Kg (not broken down)

3.72Kg Hexose (glucose)

4.79Kg of pentose (xylose)

4.79 + 3.72 = 8.51Kg of reducing sugars

6.81Kg of ethanol10.64Kg of water >2.128Kg of yeastTotal liquid = 17.45Kg

Second Generation Process: Mass Balance

Hybrid Purification

Supernatant

de

FUEL ETHANOL 99.5%

AZEOTROPE ETHANOL 65%

Water

17.45L=6.8L Ethanol10.64L Waste Supernatant

Centrifugation:Lignin, Yeast

(4.42L Ethanol)

4.23L EthanolYield 6.5% from 70Kg starting material

Dehydration

Distillation

“Distillation 2”

Water

AZEOTROPE ETHANOL 96% (4.24L Ethanol)

Water

Dehydration Methods Used.Lime (calcium oxide) or rock saltAddition of an entrainer. Adding small

quantities of benzene or cyclohexane.Molecular SievesMembranes :

Can not be exposed to high water concentration

Fouling by fusel oilsPressure reduction

SiftekTM Membrane & SystemProduced 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%.

SiftekTM MembranesHydrophilic polymer membrane Exceptional thermal mechanical and solvent

resistance propertiesMembrane is a proprietary formulation based

on polyimideProvides high flux and water/ethanol

selectivity.

BY PRODUCTSVinasse:- 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.

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 stepAlcohol components acetic acid and butyric acid esters.

Flavour and fragrance manufacturing.

Ethylbutyrate is used as pineapple-banana flavours in the food industry.

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.

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).

Cost and efficiency

Source: eubia.orgSource: Goldemberg 2008

The Economic Competitiveness of Alcohol Fuel Compared with Gasoline

Source: Goldemberg 2008

Comparison of the production costs (€/1000 liters) of ethanol in Brazil, United States and Germany.

Production costs:

Source: Goldemberg 2008

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 6,498.60Brazil 6,577.89 6,472.20 5,019.20European Union 1,039.52 733.60 570.30

 China 541.55 501.90 486.00Thailand 435.20 89.80 79.20 Canada 290.59 237.70 211.30 India 91.67 66.00 52.80Colombia 83.21 79.30 74.90Australia 56.80 26.40 26.40Other 247.27World Total 19,534.99 17,335.29 13,101.70

Source: Wikipedia.org

Brazil: Ethanol - Transport sectorYear 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

Issues: Environmental and Social Impacts of Sugarcane Production

Deforestation99.7% of sugarcane plantations are located at least

2,000 kilometres (1,200 mi) from the Amazonia

Fertilizer – water pollution

Effects on food prices

Bagassosis

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.

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.