Bioethanol biofuel renewable energy resources

RENEWABLE ENERGY RESOURCES
Lecture # 23
Presented by:
Dr. Bilal Ahmad Zafar Amin
Bioethanol_Biofuel
Solar Energy
Wind Energy
Biomass Energy
Thermal Energy
Renewable
Resources
Oil
Coal
Natural Gas
Nuclear
Non-Renewable
Resources

 Concept of biomass to bioenergy
 Classification of Biofuels (1st, 2nd, 3rd & 4th generation)
 Composition of biomass waste (lignocellulosic)
 Process of cellulosic bioethanol formation
 Illustration of pretreatment, acid and enzymatic hydrolysis
 Illustration of fermentation and distillation process
 Advantages and disadvantages of bioethanol
 Biodiesel, process, comparison to bioethanol
 Visual presentation of bioethanol process
Lecture Outlines:
Week # 15, Lecture # 1 Renewable Energy Resources

Biomass Energy Conversion Technologies
Biomass Conversion
Direct
Combustion
Thermochemical
Conversion
Biochemical
Conversion
Gasification Pyrolysis
Anaerobic Digestion (AD) Fermentation
+ O2
- O2
limited O2
- O2
- O2

 Economic growth and increasing population will lead to 2.6% p.a.
increase in global energy demand between 2015 and 2030 (IEA, 2015)
 Increasing fossil fuels cost, energy security concerns and climate change
preoccupations have motivated countries to explore alternative energy
sources, including bioenergy – energy produced through the processing
of biomass (any derived organic matter available on a renewable basis):
e.g. biogas, bioethanol, biodiesel
 Concerns about high fossil fuels prices and energy security and efforts
towards climate change mitigation are expected to feature highly in the
international agenda in the years to come. This will keep interest for
bioenergy high
Importance of Bioenergy/Biofuel

Biofuels
Liquid
Biofuels
Bioethanol Biodiesel Biobutanol
Gaseous
Biofuels
Biomethane Biohydrogn Syngas Biohythane
Classification of Biofuels
Bioethanol is an important fuel produced by the fermentation of carbohydrate rich source
which includes sugar cane, sugar beet, corn etc

Bioethanol
Environment
Better biodegradability
CO2 neutral
Higher flash point (better fire
safety)
Agriculture
Less GHG emissions (65% less)
Clean burning, low toxicity
Food security
Reduced dependence on oil
Agricultural diversification
Solution for energy crisis : Bioethanol

Edible Biomass
• Sugar beet
• Sugarcane
• Wheat
• Rice
Non-edible Biomass
• Wood
• Straw
• Grass
• Waste
Algal Biomass
• Macroalgae
• Microalgae
Genetic Engineering
• Pyrolysis
• Solar to fuel
• Engineered Algae
• Gasification
Biofuels are basically broken into two generations.
 1st generation biofuels are also called conventional biofuels. They are made from things like sugar, starch, or vegetable
oil. Note that these are all food products. Any biofuel made from a feedstock that can also be consumed as a human food
is considered a first generation biofuel.
 2nd generation biofuels are produced from sustainable feedstock. No second generation biofuel is also a food crop,
though certain food products can become second generation fuels when they are no longer useful for consumption.
Second generation biofuels are often called “advanced biofuels”.

LIGNOCELLULOSICS: a better alternative
 Can be grown on barren uncultivable land
 Need less amount of water to grow
 Does not interfere with food chain
 Available in ample amount
 Mixture of lignocellulosic biomass overcome
the problem of round the year biomass
availability
 Higher yields per hectare, either by using fast-
growing lignocellulosic plants
Second Generation Biofuel: Lignocellulosic Biomass

Composition of lignocellulosic biomass
Phenol
(C6H5OH)
Glucose
6-C sugars
(C6H12O6)
Xylose
5-C sugars
(C5H10O5)

Process for cellulosic bioethanol

Steps of conversion of cellulose and hemicellulose to Bioethanol
1. Pretreatment
2. Hydrolysis
3. Fermentation
4. Distillation of the product mixture to separate ethanol

1) Pre-treatment 2) Enzymatic
hydrolysis
3) Fermentation 4) Distillation

Pretreatment and enzymatic hydrolysis process
1) Pretreatment
The solubilization and separation of one or more of the four major components of biomass –
hemicellulose, cellulose, lignin, and extractives – to make the remaining solid biomass more
accessible to further chemical or biological treatment.
2) Hydrolysis
The breaking down of the glycosidic bonds in cellulose and hemicellulose
Acid hydrolysis
Sugars made after acid hydrolysis get converted into furfural in the acidic medium which can
act as fermentation inhibitors.
- Reaction should be rapid
- Sugars should be rapidly removed
Enzymatic hydrolysis
Bacteria and fungi are used as sources of cellulases, hemicellulases (xylanase) that could be
used for the hydrolysis of pretreated lignocelluloses.

 Fermentation is an anaerobic process that breaks down the
glucose within organic materials.
 It is a series of chemical reactions that convert sugars to
ethanol.
 The basic fermentation process involves the conversion of
a plant’s glucose (or carbohydrate) into an alcohol or acid.
 Yeast or bacteria are added to the biomass material, which
feed on the sugars to produce ethanol and carbon dioxide.
 The ethanol is distilled and dehydrated to obtain a higher
concentration of alcohol to achieve the required purity for
the use as automotive fuel.
 The solid residue from the fermentation process can be
used as cattle-feed and in the case of sugar cane; the
bagasse can be used as a fuel for boilers or for subsequent
gasification.
Fermentation and Distillation process
Animal Feed
Biomass
Pre-treatment
Solid residue
Fermentation
Distillation
Dehydration
Ethanol

Microorganisms are employed to metabolize the liberated single sugars from
enzymatic hydrolysis to convert them to bioethanol. There are two approaches:
Separate hydrolysis and fermentation (SHF):
The hydrolysis is carried out until finish, and then microorganisms are added to the
mixture to ferment the sugars. This method has some weak points, including
contamination, formation of inhibitors, and requirement of more time and extra
equipment.
Simultaneous saccharification and fermentation (SSF):
The enzymatic hydrolysis and microorganism fermentation are carried out in the
same equipment at the same time. Both enzymes and microorganisms are loaded to
the mixture. This method is proven much better than the SHF above with shorter
time, less equipment, and minimized risk of contamination.
SSF is currently considered the optimal method to convert lignocellulose to
bioethanol, reported with high conversion yield. However, there are still some small
backwards of this method. The optimal temperature for enzymatic hydrolysis is 45–
50°C, while fermentation is at its highest efficiency at 28–35°C.
Fermentation process for cellulosic bioethanol

Advantages of Bioethanol:
 Exhaust gases of ethanol are much cleaner – it burns more cleanly as a result of more
complete combustion
 Greenhouse gases reduce – ethanol-blended fuels such as E85 (85% ethanol and 15%
gasoline) reduce up to 37.1% of GHGs
 Positive energy balance, depending on the type of raw stock – output of energy during the
production is more than the input
 Any plant can be use for production of bioethanol – it only has to contain sugar and starch
 Carbon neutral – the CO2 released in the bioethanol production process is the same amount
as the one the crops previously absorbed during photosynthesis
 Energy security – esp. Countries that do not have access to crude oil resources – grow crops
for energy use and gain some economic freedom
Application of Bioethanol:
 Blending of ethanol with a small proportion of a volatile fuel such as gasoline
-> more cost effective
 Various mixture of bioethanol with gasoline or diesel fuels
– E5G to E26G (5-26% ethanol, 95-74% gasoline)
– E85G (85% ethanol, 15% gasoline)
– E15D (15% ethanol, 85% diesel)
– E95D (95% ethanol, 5% water, with ignition improver)

Disadvantages of Bioethanol:
 Biodiversity – A large amount of arable land is required to grow crops, natural habitats
would be destroyed
 Food vs. Fuel debate – due to the lucrative prices of bioethanol some farmers may sacrifice
food crops for biofuel production which will increase food prices around the world
 Carbon emissions (controversial) – During production of bioethanol, huge amount of
carbon dioxide is released – Emission of GHGs from production of bioethanol is
comparable to the emissions of internal combustion engines
 Transportation – ethanol is hygroscopic, it absorbs water from the air and thus has high
corrosion aggressiveness
 Not as efficient as petroleum – energy content of the petrol is much higher than bioethanol –
its energy content is 70% of that of petrol
 Engines made for working on Bioethanol cannot be used for petrol or diesel – Due to high
octane number of bioethanol, they can be burned in the engines with much higher
compression ratio
Future development in Bioethanol production:
 For bioethanol to become more sustainable to replace petrol, production process has to be
more efficient – Reducing cost of conversion – Increasing yields – Increase the diversity of
crop used
 As microbes are use to convert glucose into sugar which is ferment in bioethanol –
Microbiology and biotechnology will be helpful in the genetic engineering

Biodiesel:
• Biodiesel, an alternative diesel fuel, is made from renew able biological sources such as
vegetable oils and animal fats.
• Similar to petroleum diesel fuel in structure (straight chain) and number of carbon atoms
(10 to 21)
• The Biodiesel can be prepared by Transesterification.

• Triglyceride consists of glycerol backbone + 3 fatty acid tails
• The OH- from the NaOH (or KOH) catalyst facilitates the breaking of the bonds
between fatty acids and glycerol
• Methanol then binds to the free end of the fatty acid to produce a methyl ester
(biodiesel)
• Multi-step reaction mechanism:
Triglyceride → Diglyceride → Monoglyceride →Methyl esters + glycerine
Glycerine
Methyl Ester
Triglyceride Methoxide
Biodiesel from triglyceride oils

Visual presentation of Bioethanol process

Visual presentation of Biofuel and Bioethanol

Bioethanol biofuel renewable energy resources

More Related Content

What's hot

Similar to Bioethanol biofuel renewable energy resources

More from DrBilalAhmadZafarAmi

Recently uploaded

Bioethanol biofuel renewable energy resources