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
Integrated 1st & 2nd Generation Bioethanol Production from Sugarcane
Suman Swami Onyedika EgbujoEmmanuel Ogbughalu Dominic Smith Priyesh Waghmare
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
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. 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%.
First Generation Process SUGAR JUICE SUGARCANE CLEANING EXTRACTION TREATMENT SUGARCANE JUICE BAGASSE CONCENTRATIONDEHYDRATION DISTILLATION CENTRIFUGATION FERMENTATION ‘SOILDS’ANHYDROUS INTEGRATION ETHANOL OF 2nd GENERATION SUGARS
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) pathwaysPretreatment -360CPretreatment separates lignin -24hrsand hemicellulose, reduces Filtration -1- part yeastcellulose crystallinity and Separates solid and -4-parts reducing sugarincreases 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 efficiencyin the form of hemicelluloseand 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
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 FermentationPretreatment Co-fermentation-Yield = 38% - reducing sugars 26.6Kg -1- part yeast – 2.128Kgin the form of hemicellulose Filtration 4.79 + 3.72 = 8.51Kg of -4-parts reducing sugarand 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
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 DehydrationSupernatant Distillation17.45L=6.8L Ethanol10.64L WasteSupernatant Water Water Water Centrifugation: Lignin, Yeast
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
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%.
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.
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 step Alcohol 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: Goldemberg 2008Source: eubia.org
The Economic Competitiveness of Alcohol Fuel Compared with Gasoline Source: Goldemberg 2008
Production costs: Comparison of the production costs (€/1000 liters) of ethanol in Brazil, United States and Germany. 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 6,498.60 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
Brazil: Ethanol - Transport sectorYear policy Results1976 mandatory fluctuated between 10 - 25%1993 mandatory 20% E202007 mandatory 25% E252003 Introduction Flex-Fuel vehicles2008 E25-Flex vehicles 18% of Brazils total energy consumption - transport sector2009 Flex-Fuel vehicles- 92.3% of share -SUCCESS
Issues: Environmental and Social Impacts of SugarcaneProduction 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
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.