Visit Report of Biogas Plant
What is Biogas ?
Biogas is a renewable energy source produced through the anaerobic digestion
of organic materials, such as agricultural waste, manure, food scraps, and
sewage. During this process, micro-organisms break down the organic matter in
the absence of oxygen, producing methane and carbon dioxide as primary
components.
Biogas Composition
1. Methane (CH4): 50-70%
2. Carbon Dioxide (CO2): 30-50%
3. Water Vapor (H2O): 0-10%
4. Hydrogen Sulfide (H2S): 0-1%
5. Nitrogen (N2): 0-1%
Types of Biogas Plant
1. Fixed Dome Biogas Plant
2. Floating Drum Biogas Plant
3. Ballon Biogas Plant
4. Continuous Flow Biogas Plant
Required Retention Time of Various Feed Materials At 35oC
SN Raw Material Required Retention Time (days)
1 Cow dung 50
2 Poultry manure 20
3 Night soil 30
4 Rice straw 33
5 Sugarcane tops 43
6 Water hyacinth 46
Raw Material Availability And Gas Yield
SN Raw Material Production Rate Gas Yield
(m3 per kg of dry matter)
1 Cow dung 10-15 kg/day/head 0.34
2 Poultry manure 0.06 kg/day/head 0.46-0.56
3 Sheep manure 0.75 kg/day/head 0.37-0.61
4 Night soil 0.75 kg/day/head 0.38
5 Rice husk 1-1.3 tons/ha/year 5.67
6 Algae 40 tons/ha/year 0.32
7 Water hyacinth 60 tons/ha/year 0.42
Uses of Biogas Plant
Energy Production: Biogas can be used to generate electricity and heat. It can
fuel gas engines, turbines, or boilers, making it a renewable energy source.
Cooking Fuel: In many rural areas, biogas is used for cooking. It provides a
cleaner and more efficient alternative to traditional fuels like firewood or
charcoal.
Vehicle Fuel: Upgraded biogas, known as biomethane, can be used as a
renewable natural gas for vehicles, reducing reliance on fossil fuels.
Fertilizer Production: The digestate (the solid or liquid leftover after biogas
production) can be used as a nutrient-rich organic fertilizer, enhancing soil
health.
Waste Management: Biogas production helps manage organic waste,
reducing landfill use and lowering greenhouse gas emissions from decomposing
waste.
Heating: Biogas can be used for heating purposes in homes, greenhouses, or
industrial processes.
Carbon Dioxide Source: The carbon dioxide from biogas can be captured and
used in various industrial applications, including beverage carbonation and as a
feedstock for algae cultivation.
Benefits of Biogas Plant
Renewable energy: Biogas is a renewable energy source because it's
produced from organic waste, which is constantly generated.
Reduced greenhouse gas emissions: Biogas production captures methane, a
greenhouse gas that's released when organic waste decomposes.
Waste management: Biogas plants convert organic waste into a useful energy
resource, instead of sending it to landfills where it would emit methane.
Energy independence: Biogas plants allow communities to generate their own
energy, reducing their dependence on fossil fuels.
Versatile energy source: Biogas can be used for many purposes, including
electricity generation, heating, cooking, and as a vehicle fuel.
Nutrient recycling: Biogas systems can recycle nutrients in the food supply,
reducing the need for fertilizers.
Improved health: Biogas can help improve the health and well-being of
communities.
Improved soil fertility: Biogas can improve soil fertility.
Empowerment of women: Biogas can empower women by giving them more
time to pursue other activities
Construction of Biogas Plant
A biogas plant consists of an underground digester, which is a well-shaped tank
constructed of bricks and its dome-shaped roof which is made of cement and
bricks. A type of airless sealed tank is called a digestor (or oxygen). The
digester tanks dome serves as a gas storage tank or gas holder for the biogas.
The top of the dome has a gas outlet with a valve. Both the sloping inflow
chamber and the rectangular exit chamber on the digester tank’s right side are
constructed of bricks.
The exit chamber is used to remove the used dung slurry after the biogas has
been extracted, whilst the intake chamber is used to introduce new dung slurry
into the main digester tank.
While the outlet chamber is connected to the overflow tank, the inlet chamber is
connected to a mixing tank.
Working of Biogas Plant
To prepare the slurry, cow dung, and water are combined in the mixing tank in
an equal ratio.
Through the entrance chamber, this mixture of dung and water is supplied into
the digester tank.
The dome of the digester tank is left free for the collection of biogas, while the
cylindrical level of the tank is filled with dung slurry.
About 50 to 60 days pass until the new gas plant operational (starts functioning)
During this tin anaerobic bacteria break down the cow dung while there is water
present (but no oxygen), gradually transforming the process into biogas. The
dome begins to fill with this biogas.
The digester tank's slurry is under pressure as more and more biogas builds up
in the dome, which pushes the used slurry through the outflow chamber and into
the overflow tank. The used slurry is progressively evacuated from the overflow
tank. The leftover spent dung slurry from the biogas extraction process is high
in nitrogen and phosphorus compounds and makes excellent manure. More
fresh dung slurry is routinely added to the digester tank after the gas plant is
operational, which results in continuous biogas production.
Through outlet S, the biogas that has accumulated in the digester tank's dome is
removed and sent through a system of pipes to residences in the community for
use as cooking gas.
Biogas plants can also employ human excreta (human feces), in addition to the
cow dung that we currently use. Paper scrap, vegetable wastes, chicken
droppings, and agricultural wastes can all be utilized to create biogas.
