Production of Bio-ethanol from Waste Potatoes
-By Subham Kumar
-Batch(2k19), Deptt. of
Chemical Engg.
-BIT Sindri, Dhanbad
Why there is need of Bio-ethanol?
In this new era, the world is highly dependent on
various fossil energy to generate fuel, electricity
and other goods. The rapid growth of population
and Industrialization has increased the rate of fossil
fuel consumption. The excessive consumption of
fossil energy has increased the level of Greenhouse
effect. When the fossil fuels are burnt, it produces
very large amount of carbon dioxide into the air
causing global warming. Therefore, renewable
sources such as wind, water, sun, biomass and
geothermal heat can be tapped as an alternative.
The most common renewable fuel is ethanol.
However, the conventional production of ethanol
using crops such as sugarcane and corn are unable
to meet the excessive demand due to the primary
value of food and feed. This biofuel has received
significant attention recently due to global warming
and climate change. Currently, ethanol is most
widely used liquid biofuel for motor vehicles.
In our daily life we usually throw the waste potatoes
but it plays an important role for the production of
ethanol. By the fermentation of waste potatoes, a
huge amount of ethanol is produced. The potato
peels contain large amount of starch, cellulose,
hemicellulose and fermentable sugars which are
sufficient enough for the production of ethanol.
This method has an added advantage of being cost
effective, renewable and abundantly available.
It is very easy to establish this type of bio-fuel
plant by investing a small amount. Through this
process, we come to know how to make the best
use of waste potatoes.
Figure 1: - Waste potatoes
Method of Production
First of all, we need to wash the raw potatoes
so that the dust particle at the outer surface
of the potatoes get removed. After that the
mash of potatoes gets prepared by cutting or
grinding it with juicer or grinder. The slice of
potatoes are made very thin and smooth by
adding some amount of distilled water. These
smooth and silky slices are used to make a
homogeneous solution which is processed
afterwards for bio chemical or enzymatic reaction.
Our moto behind doing this procedure is to
produce maximum fermentable sugar. The
production of ethanol mostly depends on
the quality of raw potatoes. Here we will
see the production process of bio-ethanol
through enzymatic hydrolysis of waste
potatoes by adding small amount of yeast.
Manufacturing Process
The production of ethanol using yeast is one of
the simplest method for obtaining ethanol from
potatoes. Here our first objective is to prepare
mash of potatoes by heating the flour along with
water made up by grinder. Now we obtain the
solution of water with potatoes in the ratio of
2:1. Next, we heat the mash of potatoes for
30 to 60 minutes and the temperature at that
time has to be at around 50 to 60 degree C.
After 30 to 60 minutes, the solution is cooled
by lowering the temperature to 30 to 35 degree C.
Figure 2: - Shake Flask Fermentation
Figure 3: - Distilled Ethanol
Normally 2 grams of yeast is added to the diluted
mash prepared. Now we wait for the fermentation
process to begin. Fermentation is a metabolic
process wherein the microorganisms continuously
perform reaction into it. During the reaction, there
is a formation of high amount of ethanol and CO2.
For fermentation process to take place, we have
provided a solution where 2 to 3 grams of yeast is
added so that the fermentation takes place smoothly.
For increasing the rate of reaction, we usually
shake the solution many times. After that we put
the solution at stagnant position for around 84
hours at room temperature. Once the fermentation
process is completed, we move for the next step
which is distillation. In distillation process, we put
the solution at 78 degree C because the boiling
point of ethanol is 78 degree C. We again monitor
this process for around 2 to 4 hours and after
that we get the distilled ethanol.
Advantages of bio-ethanol
* Ethanol has highest number of octanes
which possess better anti-knock properties.
*There are no starting difficulties with ethanol.
*Air required for complete combustion is less.
*It has the ability to absorb the trace of moisture.
*It has ability to burn completely.
Disadvantages of bio-ethanol
*It may cause corrosion.
*It lowers the calorific value of petrol.
*It has the ability to easily get oxidized to acid.
*Air entering the cylinder need to be regulated
by modifying air inlet as less air is required for
combustion.
Conclusion
From this experiment we conclude that after
72 hours of incubation period by yeast, the
fermentable sugars has been converted to
alcohol. The reason behind the production of
great amount of ethanol from potatoes is that
the potatoes contain large amount of starch into it.
The enzymatic hydrolysis is an alternative to
produce bio-ethanol from potatoes. The production
of bio-ethanol by adding yeast is a very low-cost
process as compared to other process of the
production of bio-ethanol. It is feasible to establish
bio-ethanol plant which would be economical and
would overcome the energy crisis that’s quite
prevalent now a days.
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