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

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Introduction

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• 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

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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

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• 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

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• The United States are with over 41 % the world´s leader in ethanol production

• Feedstocks: maize wheat, barley, sorghum

South American Ethanol prodution

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• 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

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• 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

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Bioethanol Plant in Pischelsdorf, Lower Austria

Production technologyFeedstocks

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Bioethanol production of 1st generation

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• 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

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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

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• 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

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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

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Pre-treatment: Steam Explosion

Bioethanol production of 2nd generation

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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

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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

Bioethanolusage

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Thank you for your attention !