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Energy
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Biogas
Energy
Efficiency
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Gaseous Bio-fuel
or
BIOGAS
Biogas consists mainly of
methane
(about 60% to 80%) and carbon dioxide
(about 20% to 40%) with some other gases, such as
hydrogen sulfide, ammonia, and water vapour, in trace amounts. It is highly flammable and is produced through
the anaerobic (without oxygen) decomposition of organic materials from
plants and animals.
It is similar in most
respect to
Natural gas
(obtained
from
fossil fuel)
used for heating and cooking at
homes and industries. Natural gas, just like biogas
consists mainly of methane. Therefore, after undergoing some purification,
biogas can be used
just the
same way we use
natural
gas to produce heating and
cooking at homes and offices.
Biogas
is obtained
naturally from
wetlands
(e.g. swamps and marshes),
sewage sludge and from
solid waste dumps or landfill sites.
Various techniques are being
developed for the abstraction of biogas from these sources.
Biogas is also produced,
artificially, using
biogas generators/digesters.
Biogas digesters
are large air-tight tanks used to
simulate the natural processes
that produce biogas,
by allowing the digestion of organic matters from plants and animals under
anaerobic conditions.
The processes are as follows:
-
Plant materials and animal wastes (feedstock) are
shredded and placed inside the biogas
digester.
-
Water is added and the tank is closed
and properly sealed to allow no air into the tank.
-
After several days, biogas begins to
form at the top of the tank due to the activities of some bacteria
usually termed “methanogenic” bacteria (i.e. methane forming bacteria).
-
The biogas that is formed is piped
into a storage location where it can be used as needed.
-
As the production of biogas in the
generator slows down, old feeds of organic matters are taken out and new
feeds of organic matters and water added to the generator.
-
The old feeds can be dried and used as
soil manure or fertilizer.
The common feedstocks for biogas include:
-
Livestock Manure (e.g. cow dungs, pig dungs/hog, poultry
dungs etc),
-
Food processing (by-products of meat
processing, potato, dairy, cheese whey, sugar beet, pea hulls, and
vegetables); and
-
Energy crops cut as silage (wheat, barley,
triticale, clover, alfalfa, ryegrass, turnips and corn).
Unlike natural gas,
biogas is renewable; it can be replaced in a life time. It is
environmentally friendly; it reduces greenhouse gases. Methane gas from
Swamps, Landfill sites and Sewage Treatment sites, that could have
been released directly to the atmosphere are redirected for power
production. In cases where plants are planted to provide feedstocks to
Biogas generators or digesters, the plants serve as sinks to reduce the
amount of carbon dioxide released to the atmosphere.
Related pages:
Renewable Energy Resources,
Biodiesel,
Ethanol
External Biogas Links:
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