2013
Future trends of bioethanol
production(Article)
Fermentation Technology
Submitted to:Dr Tahir baig
Submitted by:komal jamim
shehzadi
Ug-4,ASAB,NUST.
FUTURE TRENDS OF BIOETHANOL PRODUCTION
J.s.komal,Atta-ur-Rehman school of Applied biosciences,National university of sciences and
technology,Islamabad,Pakistan.
ABSTRACT
Petroleum reserves of the world are depleting day by day due to its extensive use.To accomplish the
needs of the present age it is necessary to replace the petroleum with other fuel like
ethanol.Bioethanol is produced by using biomass from different sources .There are different methods
and bioreactors are developed for bioethanol production which have promising future.Agricultural
land is also reducing due to different man activities,people are scared that it might be result into the
reduction of food for mankind and animlas ,therefore different methods have been developed by using
genetic engineering to increase the biomass production from energetic crops so that large amount of
biomass is produced using small portion of the land by hybrid crops.Different techniques are also
developed like ,protein ,metabolic pathway engineering of the microbes,ultrasonic processing, and
halophytes and e-diesl development.
Introduction
Nowadays fermentation is playing a
main role in every industry
e.g.medicine, dairy etc. Likewise Bio
ethanol is also a product of
fermentation. It is a principle fuel
used as petrol substitute. Because
Ethanol has greater octane octane
number and it has replaced lead
which is used as octane enhancer in
petrol.The common mixture is made
by mixing 90% petrol and 10%
ethanol. Bio ethanol is alternative to
petrol and other fuels for flexi fuel
vehicles.
It is alcohol produced by fermentation
of the carbohydrates produced in
sugars or starch crops such as corn
and sugarcane. Cellulosic biomass
,obtained from non-food sources e.g,
grasses and trees, is also being
developed as feedstock for ethanol
production. Biomass is widely used for
bioethanol production. Biomass is a
renewable energy source, which is
derived from biological material from
living or recently living organisms. As
energy source biomass can be used as
it is, or changed into other energy
source such as biofuel. Its major
components are carbon hydrogen and
oxygen .Biomass energy is obtained
from five different main sources. These
sources are waste, garbage, and wood,
alcohol fuels, and landfill gases. Other
sources are rice mills, bagasses, sugar,
rice husk, fruit shells ,palm oil mills,
Fruits shells, Empty fruits bunch, Wood
based industries, Other agricultural
residues.
PRODUCTION
It can be made by different sources
such as potatoes, ,switch grass,sugar
beet, sugar cane, molasses corn,fruits,
Stover, straw ,wheat,other biomass ,
many types of cellulose waste as well
as reaping. Agriculture feedstock
considered as renewable because
they use solar energy and food
producing mechanism of plant.
Fig: Equipments used in bioethanol production
Material and method
These are generalized steps for
bioethanol production by any source
of biomass.


First of all the size of the
biomass is reduced to make is
feasible for handling as well as
to increase the efficacy of
production
process
.e.g.
agriculture residues go through
grindins process and wood go
through whittle process to
achieve similar particle size.
In the second step biomass is
broken
down
into
simple
sugars,biomass is mixed with
dilute sulfuric acid and a chemical
reaction hydrolysis take place.In
this type of reaction multiplex
and heavy chains of the
carbohydrates broken down into
simpler sugars.These complex
sugars are converted into mixture
of arabinose,xylose,mannose,and
galactose.Cellulose
is
also
converted into glucose.

Enzymes are produced in third
step
.Enzymes
can
also
purchased
from
commercial
enzyme markets.

The next step is cellulose
saccharification, in this enzymatic
hydrolysis remaining cellulose is
converted into glucose by using
cellulase.

In this step ethanol is produced
by fermentation.It is a series of
reaction caused by microbes
e.g,bacteria or yeast which uses
sugars as a food.As microbes
use sugars as a consequences
carbon dioxide and ethanol
produced.

Hemicellulose fraction of biomass
has plenty of pentoses in which
xylose is the dominant one,in this
step fermentation of xylose is
take place by using genetically
engineered bacteria zymomonas
mobilis.

Ethanol is recovered in this
step,ethanol is disparated from
other constituents of the broth,at
the end dehydration removes the
water from the ethanol.

There are other by products are
produced
during
ethanol
production which can be used for
different purposes e.g,electricity
generation.
Fig: Schematic diagram for bioethanol production
Future horizon of bioethanol production
Shortage of agricultural land leads to
the
advances
in
metabolical
pathway engineering and genetic
engineering
of
the
different
microbes.in which they Broadens the
substrate range such as arabinose
and xylose in strains e.g,Escheichia
coli , streptomyces sp. And
zymomonas mobilis. According to
recent advances in fermentation
technology
cellulose
and
hemicellulose
are
efficiently
deplymerize into simple sugars In
lignocellulose to ethanol process
.Pentose sugar is present in the
lignocellulosic
material
which
reduces
the
energy
demand
because it takes less time and
energy to break the the five carbon
sugars than complex one.
Genetic Engineering of plants
Genetic engineering of plants will also
play important role in biofuel industry.By
using genetic engineering tools and
technology we can develop
hybrid
varities of energetic crops which will
greatly increases the starch yield which
in turn increases the biomass for
ethanol production and also helps in
economical gains an example of this is
improved hybrid corn.Halophytes are
also developed
which
are saline
tolerant .It reduces the use of the
agricultural land which is used for food
production.
Protein Engineering.
If we modify the amino acid sequence of
the enzyme or proteins we can enhance
the efficiency of enzymatic hydrolysis. It
will reduces the time as well as
increases the efficiency of the reaction.
Development of the oxygenated
diesel
It is also known as E-Diesel.It is
produced by direct mixing of the
bioethanol and diesel fuel.It has
appreciating role in reducing particulate
emission.Another advantage is that it
has low production cost.But the obstacle
in using this process is that ethyl alcohol
is ordinarily immiscible with the diesel it
requires surfactants to reduce the
surface tension and proper mixing.
Ultrasonic processing
It has been Recently seen that
ultrasonic processing used in biodiesel production increases
a
biodiesel yield in excess of 99% in
five minutes or less.While in
conventional batch reactor systems it
take an hour or more.
Hurdles In using bioethanol and
thrash to the problem
Along with the benefits there are
also drawbacks associated with the
ethyl alcohol . The major hurdles in
using ethyl alcohol as transport fules
are,it picks up water with it ,it is also
corrosive ,it is volatile and has low
energy density.This problem can be
overcome by replacing ethanol with
other alcohol such as butanol.Butanol
has four carbon atoms in its structure
and has lower volatility rate and
increased energy density which can be
used as efficient transport fuel.US has
produced butanol experimentally by
using sugar beet and cellulosic
feedstock.
Results
Bioethanol
comes
from
renewable
resources.
It
is
biodegradeable and far less poisonous
than fossil fuels.It has Benefit over fossil
fuel is that it cause reuction in
greenhouse gas emissions. Bioethanol
can be easily homogenized into existing
road transport fuel system.Mixing of
bioethanol with petrol will ensure greater
fuel securety avoiding heavy reliance on
oil producing nations.
Conclusion
Research and development of new
strains and modification in their different
metabolic pathways will tremendously
increase the fermentation of bioethanol.
New designs of bioreactors will also play
an important role in bioethanol production.
It is a need to discover High yielding
process to make bioethanol ruthless with
other fuels such as biodiesel in the future.
A growing ethanol industry will provide
jobs in plant operations and maintenance
and contribute to rural economic
development.
Refrences
1)Institute of Sustainable Halophyte Utilization, University of Karachi, University Road, Karachi 75270,
Pakistan
2)Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai,
Tsukuba, Ibaraki, Japan
3) Food Engineering Research Division, National Food Research Institute, 2-1-12 Kannondai, Tsukuba,
Ibaraki, Japan
4) Graduate School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, Hokkaido,
Japan