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Biogas
What is Biogas, its advantages &
disadvantages
types of biogas digesters
Natural
Energy Hub
Cooking
gas is on very high demand now, as we know. But while taking price into
consideration, it doesn’t seem to be economical.
There
comes the relevance of biogas.
Biogas
can be produced by us.
Here
we talk about what is Biogas, history and
origin of biogas, its advantages and disadvantages, types of biogas
digesters and the process of
anaerobic digestion.
Biogas
refers to a fuel gas obtained from the decaying of organic matter.
This
combustible gas is a mixture of methane and carbon dioxide formed by the
bacterial decomposition of sewage, garbage or plant crops, green waste and
manure in the absence of oxygen.
The
breakdown of organic matter in the absence of oxygen is called anaerobic
digestion. This takes place in a large tank commonly known as digester.
Inside
the digester, bacteria convert the organic waste into biogas. Thus, biogas is
produces by anaerobic digestion by anaerobic bacteria or by fermentation of
biodegradable waste.
This renewable source of energy has
traces of hydrogen sulfide, ammonia, water, nitrogen and hydrogen.
When
gases like methane, hydrogen and carbon monoxide gets oxidized with oxygen, the
energy released in this process allows biogas to be used as a fuel.
HISTORY
OF BIOGAS
Early in the 17th century, Jan
Baptita Van Helmont found that flammable gases could be evolved from decaying
matter.
By 1776, Count Alessandro Volta concluded a
correlation between decaying matter and the gases evolved.
In 1808, Sir Humphry Davy determined traces of
methane in biogas.
So, in 1859, the first digestion plant was built
in Mumbai.
In 1895, biogas was used to fuel street lights
in England.
Finally, microbiology was developed as a science
and by 1930, Buswell and many other scientists discovered anaerobic bacteria and
the suitable conditions that promote the production of methane.
In the modern world more and more countries are
into using sophisticated system in biogas.
· Ecofriendly : Biogas is evolved through
anaerobic digestion that means no oxygen is need for its production. This
technically means that no form of combustion is evolved thus no green house
gases are released. Thus biogas is environment friendly.
· Renewable : Biogas is a renewable source of energy.
All the products used such as garbage, sewage, residues of crop, manure and
green manure are and will be available in plenty. So biogas can be produced on
a regular basis.
· Reduce
soil pollution :
All the products used in the production of biogas are ecofriendly and are
biodegradable. Mixed with soil, it becomes manure and increases the fertility
of the soil thus reducing soil pollution.
· Low
investment :
Biogas can be developed at home with a very low cost and investment. The raw
materials used can be obtained free of cost. The gases evolved can be easily
used for cooking and generating electricity. If biogas is compressed, natural
gas can be obtained and used to power automobiles.
· Healthier
generation :
The byproducts of biogas generation can be used as organic manure (digestate)
which is rich in nutrients. This can be used as a perfect supplement for
chemical fertilizers thus reducing health complications.
· Employment : The biogas industry has created a large
number of employment opportunities in many countries. Umpteen number of people
are hired for raw material collection and biogas generation.
· Healthy
cooking alternative :
Biogas is a healthy cooking alternative and it’s economical too. This helps
women and children especially in the rural areas from firewood collection.
Cooking on gas stove is always a healthier better option as compared to cooking
over an open fire.
· Improves
water quality :
Anaerobic digestion reduces and deactivates pathogens and parasites. This in
turn reduces water pollution and water born diseases.
· Reduces
fossil fuel use :
The uses of fossil fuels like oil, coal and
gas can be reduced to a great extend as the use of biogas is increased. This
has further helped countries like India and china as they have invested a lot
in biogas plants and its development.
· Contains
impurities :
The biofuel used for automobiles contains impurities that can cause erosion to
the metal parts. This increases the maintenance cost of the vehicles. This is
more suitable for household purposes.
· Cannot
meet demand :
Biogas is in great demand because of its low cost. But unfortunately the
technologies now are not that efficient so produce as much to meet the
requirements. In most of the countries, the government is not willing to invest
more on these biogas plants.
· Not
suitable for all areas :
Biogas can be used in areas where raw materials are available in plenty. Mostly
these are available in plenty in rural areas. So it’s only practical to build
biogas plant in rural areas.
· Not
economically attractive :
Since the raw materials used are cheaply available it is not economically
attractive.
· Affected
by weather :
Like most of the renewable source of energy, biogas also has temperature
effects. The ideal condition for bacteria to act is warm climate. So it is
difficult to set up a biogas in areas where the climate is cold.
· Fixed
dome biogas plants :
This is a dome shaped with immovable gas holder and a displacement pit. The
upper part of the digester stores the gas and the waste is displaced in the
displacement pit. When the volume of the gas increases, the pressure increases.
· Floating
drum biogas plants :
This consists of underground digesters and movable gas holders. The gas gets
collected in the drum which is above the digester. This moves up and down
according to the gas collected.
· Balloon
plants : This consist of a
rubber bag or balloon and it combines the digester and gas holder. The input
and output is connecter to the skin of the rubber bag.
BIOCHEMICAL
PROCESS IN ANAEROBIC DIGESTION
The process of anaerobic digestion can be
divided into 4 stages like hydrolysis, acidogenesis, acetogenesis and
methanogenesis.
· Hydrolysis : In this stage the organic compound is
degradated into simple form so that micro organisms can utilize them easily. The
rate of hydrolysis depends on lot of factors like organic substance shape,
surface area, size and biomass.
· Acidogenesis : This is the second step and it involves
fermentation. This is one of the quick steps in anaerobic digestion. Here the
anaerobic microbes further degradate the products into simpler compounds like
volatile fatty acids and acetic acid.
· Acetogenesis : The volatile fatty acids and acetic acid
produced in acidogenesis cannot be utilized by methanogenesis, so it is further
simplified into acetate and hydrogen. This process of conversion is known as
acetogenesis carried out by acetogens which are sensitive organisms.
· Methanogenesis : This is the last step in anaerobic
digestion. Here the methanogenic bacteria convert acetate to methane and carbon
dioxide. This is an important pathway in yielding energy. Methanogenic growth
is of key importance in anaerobic processes. The methanogens and acetogens
share a mutually beneficial relationship which maintains equilibrium in
anaerobic process.
To conclude, biogas technology can be used in
different ways to contribute to its development.
Farmers can use it as a substitute for chemical
fertilizers for developing healthy crops. Industries can use it for generating
light and heat.
Municipalities can use this to solve problems
like waste disposal and waste water treatment.
The national government can use this for the
overall development of the country like reduce deforestation, increase
agricultural productivity and reduce the use of chemical fertilizers.
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useful resources about our Nature, Green Energy , Organic health and natural
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