Transcript Folie 1

Biogas typically refers to a gas produced by the biological breakdown of organic
matter in the absence of oxygen. Biogas is comprised primarily of methane and carbon
dioxide. It originates from biogenic material and is a type of biofuel and it’s a product of the
anaerobic digestion or fermentation of biodegradable materials such as manure or
sewage, municipal waste, and energy crops.
The methane in biogas gives
it the ability to be used as a fuel.
The
combustion
of
which
releases energy. In developing
countries biogas can be used as
a low-cost fuel for cooking. It can
also be utilised in modern waste
management facilities where it
can be used in gas engines to
generate electricity. Biogas is a
renewable fuel and electricity
produced from it can be used to
attract
renewable
energy
subsidies in some parts of the
world.
Production
Composition
Applications
Biogasmax European Project
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Depending on where it is produced, biogas can also be called swamp, marsh, landfill
or digester gas. A biogas plant is the name often given to an anaerobic digester that
treats farm wastes or energy crops.
Biogas can be produced utilising anaerobic digesters. These plants can be fed with
energy crops such as maize silage or biodegradable wastes including sewage sludge
and food waste.
Landfill gas is produced by
organic waste decomposing under
anaerobic conditions in a landfill. The
waste is covered and compressed
mechanically and by the weight of
the material that is deposited from
above. This material prevents
oxygen from accessing the waste
and anaerobic microbes thrive. This
gas builds up and is slowly released
into the atmosphere if the landfill site
has not been engineered to capture
the gas. Landfill gas is hazardous for
three key reasons. Landfill gas
becomes explosive when it escapes
from the landfill and mixes with
oxygen within lower and higher
explosive limits.
The methane in biogas forms
explosive mixtures in air. The lower
explosive limit is 5% methane and
the upper explosive limit is 15%
methane. The methane contained
within biogas is 20 times more
potent as a greenhouse gas than
carbon
dioxide.
Therefore
uncontained landfill gas which
escapes into the atmosphere
significantly contributes to the
effects of global warming. In
addition to this volatile organic
compounds
contained
within
landfill gas contribute to the
formation of photochemical smog.
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Typical composition of biogas[2]
Matter
%
Methane, CH4
50-75
Carbon dioxide, CO2
25-50
Nitrogen, N2
0-10
Hydrogen, H2
0-1
Hydrogen sulphide, H2S
0-3
Oxygen, O2
0-2
The composition of biogas varies
depending upon the origin of the
anaerobic digestion process. Landfill gas
typically has methane concentrations
around 50%. Advanced waste treatment
technologies can produce biogas with
55-75%CH4.
In some cases biogas contains
siloxanes. These siloxanes are
formed
from
the
anaerobic
decomposition of materials commonly
found in soaps and detergents.
During
combustion
of
biogas
containing siloxanes, silicon is
released and can combine with free
oxygen or various other elements in
the combustion gas. Deposits are
formed containing mostly silica (SiO2)
or silicates (SixOy) and can also
contain calcium, sulphur, zinc,
phosphorus. These white mineral
deposits build to a surface thickness
of several millimetres and must be
removed by chemical or mechanical
means.
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Electricity
Biogas can be utilised for
electricity production, space heating,
water heating and process heating. If
compressed,
it
can
replace
compressed natural gas for use in
vehicles, where it can fuel an internal
combustion engine or fuel cells.
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Biogasmax is a large-scale
integrated project funded by the
European Commission in order
to
ensure
the
market
penetration of biogas as a
vehicle fuel. The European
Biogasmax project creates a
network
of
biogas-related
demonstrations in order to
share
best
practices
in
managing sustainable urban
transportation.
The
cities
involved in Biogasmax include
Stockholm, Gothenburg, Lille,
Rome and Berne.
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Made by:
Molcut Oana Carla Maria
Lep Iulia Teodora
Coordonated by:
Schnabel Dieter