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Bioethanol Productionof 1st and 2nd Generation
3rd REBEL Partner Meeting, 27 May 2010 Sara Helmberger
Upper Austrian University of Applied Sciences Research and Development Ltd, Campus Wels
Content
• Introduction
• World-leading bioethanol producing countries
• Bioethanol production of 1st and 2nd generation
• Various possible feedstocks
• Production and processing technologies
3rd REBEL Partner Meeting, 27 May 2010 page 2
Introduction
3rd REBEL Partner Meeting, 27 May 2010 page 3
• Fossil fuels are responsible for 73 % of the CO2 production in the atmosphere
• Extreme contribution to global warming
• Interest in development of methods, reducing green house gases
• Bioethanol as alternative to petroleum-derived transportation fuels
3rd REBEL Partner Meeting, 27 May 2010 page 4
Definition Bioethanol
• Ethyl alcohol, grain alcohol, CH3-CH2-OH or EtOH
• = Liquid biofuel
• Advantages, compared to gasoline:
- higher octane number- broader flammability limits- higher flame speeds- higher heats of vaporization- higher compression ratio- shorter burn time
• Possible feedstocks: plant oils, sugar beets, cereals, organic waste, processed biomass
• Disadvantages, compared to gasoline:
- lower energy density- its corrosiveness- low flame luminosity- lower vapor pressure - miscibility with water
World-leading bioethanol producing countries
3rd REBEL Partner Meeting, 27 May 2010 page 5
• World-wide production of fuel ethanol more than tripled from 2000 until now
• About 60% of global bioethanol production are obtained from sugar cane and 40% from other crops (e.g. maize)
North American Ethanol production
3rd REBEL Partner Meeting, 27 May 2010 page 6
• The United States are with over 41 % the world´s leader in ethanol production
• Feedstocks: maize wheat, barley, sorghum
South American Ethanol prodution
3rd REBEL Partner Meeting, 27 May 2010 page 7
• South America contributes with roughly 35 % to world´s ethanol production, with Brazil being the leader country
• Feedstock: sugar cane
• ~ 20 % exported to US, EU, others
European Ethanol production
3rd REBEL Partner Meeting, 27 May 2010 page 8
• Europe contributes with 9 % to world´s ethanol production-> Comparable to the US ethanol market of roughly ten years ago
• Plants in France, Spain, Sweden, UK, Austria (Pischelsdorf, Lower Austria)• In 2000, the EU introduced a Biofuel Directive• Commission of the European Communities (2007) -> binding minimal target
of 10 % biofuels by 2020
• Feedstock: wheat, sugar beet, waste from the wine industry
European Ethanol production
3rd REBEL Partner Meeting, 27 May 2010 page 9
Bioethanol Plant in Pischelsdorf, Lower Austria
Bioethanol production of 1st generation
3rd REBEL Partner Meeting, 27 May 2010 page 11
• Major feedstocks for world´s ethanol production:
Sugar-containing feedstock: Sugar cane Starchy feedstock: Maize
Bioethanol production of 1st generation
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Starchy materials (e.g. maize)
• US: 2 types of maize processing facilities:
- Wet milling (since 1980s)- Dry grind (newer technology)
• Starch = a polysaccharide carbohydrate, with a large number of sugar-molecules
• Break down of the chains of this carbohydrate to obtain the single (individual) sugars -> Hydrolysis technique
• Fermentation with microorganisms (e.g. yeasts)
Bioethanol production of 1st generation
3rd REBEL Partner Meeting, 27 May 2010 page 13
Sugar-containing feedstocks (e.g. sugar cane, beet molasses, sweet sorghum)
• provide the single sugars (e.g. sucrose, glucose and fructose), which can be readily fermented by microorganisms (yeast) -> no hydrolysis is necessary
• Brazil: sugar cane- harvest- pressing- Fermentation of sugar juice by microorganisms (yeast)
• Europe: Beet molasses
• Developing countries (e.g. Africa): Sweet sorghum
Bioethanol production of 2nd generation
3rd REBEL Partner Meeting, 27 May 2010 page 14
• Feedstocks: Alternative or lignocellulosic materials
• = non food crops:
- waste and remnant biomass - stalks of wheat and corn- wood- grass- straw
• These most abundant reproducible feedstocks on Earth are of
- high yields- low costs- good suitability for low quality land- low environmental impacts
Bioethanol production of 2nd generation
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Lignocellulosic biomass
• 3 basic polymers: - Cellulose- Hemicelluloses - Lignin
• Processing of lignocellulosic material to bioethanol1. Pre-treatment2. Hydrolysis
3. Fermentation4. Product separation
Bioethanol production of 2nd generation
3rd REBEL Partner Meeting, 27 May 2010 page 16
Pre-treatment
• Size-reduction
• Removal of structural and compositional impediments -> Lignocellulosic biomass is made more accessible for subsequent hydrolysis
• Pre-treatment possiblities:- mechanical- chemical - biological pre-treatment- “Steam Explosion”
• Steam Explosion:
- Biomass is extruded at high temperature and pressure
Bioethanol production of 2nd generation
3rd REBEL Partner Meeting, 27 May 2010 page 17
Pre-treatment: Steam Explosion
Bioethanol production of 2nd generation
3rd REBEL Partner Meeting, 27 May 2010 page 18
Hydrolysis
• = Saccharification of lignocellulosic biomass
• Cellulose and Hemicellulose have to be broken down into single (individual) sugar molecules
• Catalyst:
- dilute acid - concentrated acid - enzymes (so-called cellulases)
• Enzymatic hydrolysis- Cellulases are produced from both fungi and bacteria - Hydrolysis at mild conditions (50°C and pH 5.0)- Effective cellulose and hemicellulose breakdown
Bioethanol production of 2nd generation
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Fermentation
• The hydrolysate (mixed sugar-solution) is then fermented by microorganisms (e.g. yeast)
• The sugar-solution contains not only one kind of sugar, but several different kinds-> Microorganisms are required, that can convert all sugars to high yields of EtOH
• Most effective producer of bioethanol: Saccharomyces cerevisiae
- can ferment only one kind of sugar
- metabolic engineered strain or adapted strain of yeast is required
Bioethanol production of 2nd generation
3rd REBEL Partner Meeting, 27 May 2010 page 20
Product separation, Distillation
• Distillation
- Bioethanol is separated from water - Ethanol is concentrated to about 95.6 %
• Value-added co-products (e.g. lactic acid)
- processing into plastics or other products
• Lignin
- usage in various value-added applications