Basic introduction of biogas.

2. *Biogas is a mixture of gases produced by the breakdown
of organic matter in the absence of oxygen.
*It is a renewable energy source.
*It is produced by anaerobic digestion of biodegradable
materials such as manure, sewage, municipal
waste, green waste, plant material, and crops.
*It is primarily methane (CH4) and carbon dioxide (CO2)
and may have small amounts of hydrogen sulphide (H2S),
and moisture.
*Combustion of these gases produces energy.

3. *Ignition temperature is between 650 and 750C.
*Calorific value is 18.7 to 26 MJ/m3
* Explosion limit: 5 to 14 % in air.
*Air to Methane ratio for complete combustion is
10 to 1 by volume.
*One cubic meter of biogas is equivalent to 1.613
liter of kerosene or 2.309 kg of LPG or 0.213 kW of
electricity.

4. *Biogas is produced in a
biogas plant.
*A biogas plant is an
anaerobic digester that
treats farm wastes or
energy crops.
*These plants can be fed
with energy crops such as
maize silage
or biodegradable
wastes including sewage
sludge and food waste.
*During the process
(anaerobic digestion), an
air-tight tank transforms
biomass waste into
methane.

8. Typical composition of biogas
Compound
Molecular
formula
%
Methane
CH4 50–75
Carbon dioxide
CO2 25–50
Nitrogen
N2 0–10
Hydrogen
H2 0–1
Hydrogen sulphide
H2S
0–3
Oxygen
O2 0–0

9. Heating
•No pre-treatment required
•Easiest way to use biogas
Power generation
•Both electricity and heat can be
produced in the composition of
35% and 65% respectively
Vehicle fuel
•Requires considerable processing
•Water, impurities and particles must be removed
•Great environmental factors
Gas network
•Natural gas being used for gas
cookers, heaters, baking ovens,
water heaters etc.
Industries
•Used for heating premises, district
heating power production, heating
ovens etc.

10. *Provides a non-polluting and renewable source of energy.
*Efficient way of energy conversion (saves fuel wood).
*Saves women and children from drudgery of collection and
carrying of firewood.
*Produces enriched organic manure.
*Leads to improvement in the environment, and sanitation
and hygiene.
*Provides a source for decentralized power generation.
*Leads to employment generation in the rural areas.

11. *Household wastes and bio-wastes can be disposed
of usefully and in a healthy manner.
*The technology is cheaper and much simpler than
those for other bio-fuels, and it is ideal for small
scale application.
*Any biodegradable matter can be used as substrate.
*Anaerobic digestion inactivates pathogens and
parasites, and is quite effective in reducing the
incidence of water borne diseases.
*Biogas plants significantly lower the greenhouse
effects on the earth’s atmosphere.

12. *The process is not very attractive economically (as
compared to other biofuels) on a large industrial scale.
*It is very difficult to enhance the efficiency of biogas
systems.
*Biogas contains some gases as impurities, which are
corrosive to the metal parts of internal combustion
engines.
*Not feasible to locate at all the locations.

13. *Biogas is a renewable
source of energy.
*It is produced by
anaerobic digestion in a
biogas plant by bacteria
present in the slurry.
*It mainly consist of
methane and carbon
dioxide gases, which can
be used in various heat
and power generating
processes.
*It is economically and
environmentally
beneficial.