This work concerns a systematic study of IC engine operation with 100% biogas as fuel (as opposed to the dual-fuel mode) with particular emphasis on operational issues and the quest for high efficiency strategies. As a first step, In Biogas CO2 does not help in combustion process but reduce the calorific value of biogas. H2S is in minor quantity but it has corrosive action on combustion chamber and also reduces calorific value of biogas. Also traces of moisture are to be removing for better thermal efficiency. So harmful gradients are removed and use only methane as a fuel. Subsequently, the model of KINETIC GF is used to predict effect of different parameters such as compression ratio, spark timing and combustion durations on engine performance and efficiency. The results show very high overall efficiencies with the manifold injection strategy. The main reasons are the higher volumetric efficiency and overall lean operation of the engine across the entire load range. Predictions show excellent agreement with measurements, enabling the model to be used as a tool for further study. Simulations suggest that a higher compression ratio (up to 13) and appropriate spark advance can lead to higher engine power output and efficiency.

1. 1
Biogas as a Vehicle Fuel
Suryavanshi N. D, Shaha S. S, Varpe D.G
Department of Mechanical Engg., S.V.P.M.’s College of Engineering
Abstract— This work concerns a systematic study of
IC engine operation with 100% biogas as fuel (as
opposed to the dual-fuel mode) with particular
emphasis on operational issues and the quest for high
efficiency strategies.
As a first step, In BiogasCO2 does not help in
combustion process but reduce the calorific value of
biogas. H2S is in minor quantity but it has corrosive
action on combustion chamber and also reduces
calorific value of biogas. Also traces of moisture are to
be removing for better thermal efficiency. So harmful
gradientsare removed and use only methane as a fuel.
Subsequently, the model of KINETIC GF is
used to predict effect of different parameters such as
compression ratio, spark timing and combustion
durations on engine performance and efficiency.
The results show very high overall efficiencies
with the manifold injection strategy. The main reasons
are the higher volumetric efficiency and overall lean
operation of the engine across the entire load range.
Predictions show excellent agreement with
measurements, enabling the model to be used as a tool
for further study. Simulations suggest that a higher
compression ratio (up to 13) and appropriate spark
advance can lead to higher engine power output and
efficiency.
Keywords—Anaerobic Digestion, Gasoline,
Scrubber.
1. Introduction
For developing countries such as India,
energy is at a premium due to the large dependence
on crude oil imports. At the same time substantial
part of the rural population still does not have
access to electricity. While fossil fuel usage
increases it is only a matter of time before reserves
run out. The use of renewable energies would
provide the benefit of alternative possibilities to
future energy needs. One of the sources of
renewable energy is biomass.
There are different ways of utilizing biomass.
Firstly, it can be burnt directly; this method is most
common. The heat generated can be used to power
boilers and the steam produced is used in various
industrial processes or can be used for running
steam turbines. It can be subjected to gasification
where part of the biomass is converted to producer
gas consisting of CO, H2, CH4, CO2, N2, which
can be used for cooking, heating or for running
internal combustion engines. The different
methods to use biogas in IC engines are
1. Dual-Fuel Operation (C.I. Engines)
2. C.I. Engine conversion
3. S.I. Engine conversion
2. Background
Operation of SI engines on biogas requires
changes in the intake system to supply gas.
Keeping in mind the requirement of a simple
system, an earlier investigation looked into the
possibility of modifying a commercially available
Shriram Honda EBK 1200 genset on biogas. The
genset was successfully run on 100% biogas. An
initial modification to the engine so as to supply
gas at the intake manifold was done. The gas was
introduced directly into the intake manifold. The
system utilized a pump to supply gas with manual
control for gas flow rate. A maximum of 400 W of
electrical energy was obtained in comparison to
1000 W for kerosene operation. An overall
efficiency of 8% was obtained on gas operation
with 5% improvement in efficiency as compared to
kerosene operation. This is attributed to the simpler
combustion process of gases when compared to
liquid fuels. The overall efficiency of the system is
very low as a result of the low compression ratio of
the engine (4.5). This is due to the low octane
number corresponding to kerosene.

2. 2
3. Theory
3.1 Preparation of Bio-gas
Micro Organisms and Mechanism of Bio-
Gas Production are
A. Micro Organisms-
An organic waste consist of many
organisms but the organisms useful for
Biogas productions are
i. Aerobic
ii. Anaerobic
B. Constituents of Organic Waste –
The organic waste contains many
constituents such as cellulose, Hemicelluloses,
lignin, proteins, and starch, water-soluble, fats
Soluble etc.
C. Mechanism of biogas production: -
Stage 1 -
It involves the decomposition of cellulose,
hemi cellulose, Lignin, starch, protein, fats etc.
Into simpler organic compounds like acids,
alcohols and gases like CO2, H2, and NH3, H2S
etc. by aerobic and anaerobic Micro-organisms.
Stage 2 -
The anaerobic organism or methane
bacteria utilize Simple carbon compounds
available from first stage and produce methane.
There are two types of plants-
i. Daily fed or continuous type.
ii. Batch fed or periodic type.
Biogas coming from tank contains
Components Composition
Methane(CH4) 50-68%
Carbon monoxide (CO2) 25-35%
Hydrogen(H2) 1-5%
Nitrogen (N2) 2-7%
Hydrogen Sulphide (H2S) 1-5%
3.2 Purification of Biogas
1) Removal of CO2 -
CO2 is highly corrosive when wet and it
has no combustion value so its removal is must to
improve the biogas quality. To remove CO2 we
use Caustic solution of NaOH 25%
NaOH + CO2 = NaHCO3
2) Removal of H2S -
The ferrous materials are placed in a closed
gas tight container the gas to be purified flows
through the ferrous absorbing agent from the
bottom & leave the container at top.
CuSO4+H2S= CuS+H2SO4
By using following setup Biogas can be
pure.
Fig. Setup for Purification of Biogas
3.3 Properties of bio-gas
In its pure state, it is color less, odorless,
tasteless. For safety reason, an odorant is added so
that any leak can be easily detected because of
typical smell
The composition of bio gas is never
constant. Methane is by far the largest component,
its presence accounting for about 95% of the total
volume. Methane is a simple hydrocarbon, a
substance consisting of carbon & hydrogen. There

3. 3
are many of these compounds each has its own
carbon & hydrogen atoms joined together to for a
particular hydrocarbon gas as fuel gas. Methane is
very light fuel gas. If we increase the number of
hydrogen & carbon atoms, we have got
progressively heavier gases, releasing more heat,
therefore more energy, when ignited. Specific
gravity of methane is .55 which is less than petrol
& LPG. This means that biogas will rise if
escaping, thus dissipating from the site of a leak.
This important characteristic makes biogas safer
than other fuels. It does not contain any toxic
component; therefore there is no health hazard in
handling of fuel. The air to biogas (stoichiometric)
ratio by volume for complete combustion is 9.5:1
to 10:1.
Biogas has a very slow flame velocity, only
.290 m/s. at its highest. The range of flammability is
4 to 14% which can give good combustion
efficiency
Biogas has very high octane number
approximately 130. By comparison, gasoline is 90
to 94 & alcohol 105 at best. This means that a
higher compression ratio engine can be used with
biogas than petrol. Hence, cylinder head of the
engine is faced so that clearance volume will be
reduced & compression ratio can sufficiently
increase. Thus volumetric efficiency & power
output are increased. Because of its high octane
value the detonation occur however high the
compression may be. The Boiling point of biogas
is above 300 degree Celsius while the calorific
value is 35.390 MJ/m3.
3.4 Advantages of Biogas : -
1) It is light fuel gas.
2) It mixes easily with the air.
3) It is highly knocked resistant.
4) Due to uniform distribution thermal
efficiency is higher.
5) Biogas has a high octane number.
6) It reduces pollution.
7) Higher compression ratio can be used
with biogas.
8) Plants capital cost is low.
9) Domestic fuels for burners used in
kitchen
10) No toxic to skin
3.5 Methane combustion duration
The flame propagation speed of methane is
known to be lesser than that of gasoline the
ignition delay for methane is also greater using
natural gas in spark ignition engine therefore
requires the spark timing to be advanced spark
timing is not sufficient with conventional
conversion .the long duration combustion implies
that merely advancing spark plug timing is not
sufficient with conventional conversion this is
because the temperature in cylinder at an timing
would be lesser. These lower temperature would
further hinder early flame development. The longer
the time taken for combustion implies lower heat
release rate and therefore lower indicated power.
The long ignition delay for these engines is result
of strong initial endothermic phase in case of
natural gas combustion.
The presence of CO2 in biogas further extends the
combustion period experiment were preformed on
a single cylinder engine CFR engine. He reports a
significant increase in the average length of
combustion period, ignition lag and lower
associated burning rates for with increasing
proportions of carbon dioxide.
3.6 Efficiency
Natural gas and biogas have been found to
posses good resistance to knocking their octane
numbers are higher than that of petrol with natural
gas at 120 relative to natural gas and gasoline were
studied using experiment simulated biogases with
three compositions 15% CO2, 25% CO2 and 38%
CO2 by volumes were tested the compression
ratios were varies from 8.5 to 13. The gaseous
fuels were found to have leaner operation limits in
comparison to gasoline. The maximum

4. 4
compression ratios recommended for gas operation
is 1.3 the use of higher compression ratios
increases the indicated power but the mechanical
losses also increases thereby reducing the net brake
power available. Compression ratios beyond 15 led
to knocking. The long combustion duration of
biogas requires the spark timing to be advanced.
The choice of compression ratio for biogas thus
based on to some extent.
3.7 Modification in IC Engine
Dual-fuel operation refers to utilizing
biogas in diesel engines with diesel as pilot fuel for
the purpose of ignition of fuel. In this method, in
place of pure air that fills the combustion chamber
of the engine prior to diesel injection, a suitable
mixture of air and biogas is introduced. A small
amount of diesel usually 10 – 20% is sprayed so as
to initiate combustion. Thus, a mixing device for
air and biogas is required. For stationary
applications speed control is obtained using a
regular governor. This method requires a constant
supply of diesel.
A conventional C.I. engines can be
converted for biogas operation. However, as diesel
engines usually have compression ratios higher
than 14, this can cause problems of knocking with
biogas. Hence a reduction in compression ratio
below 13 is required for biogas operation. Also, the
injector present needs to be replaced with a spark
plug to provide for the ignition of the air-biogas
mixture. Thus, significant changes to the engine
are required.
Gasoline spark ignition engine conversion
is relatively straightforward requiring a mixing
device for the purpose of air-fuel ratio control and
spark timing modification to account for the slow
combustion of biogas. Thus, either one could adapt
a diesel engine by reducing its compression ratio
for safe biogas operation or convert a spark
ignition engine to higher compression ratio for
more efficiency.
4. Experimental procedure
Following description gives detailed
procedure of performance test on 4 stroke petrol
engine. The experimental setup is done as stated
above. First of all make all colorimeter and
Alternator connection to engine. Calorimeter and
Alternator is on the desired flow rate and pressure,
make sure fuel supply on. After conditioning the
equipment, the engine is started and warm up for
10 min without applying any load. Observe the fuel
flow timer when started the engine. Two tests are
taken viz. varying speed and load & second are by
keeping speed constant & varying the load.
Respective readings are noted and calculations are
done to find performance parameters. Repeat same
procedure for biogas and LPG.
A) On CI engine (Diesel):-
Fig.5.2.1 Setup for CI engine testing
B) On SI engine (Petrol):-
Fig.5.2.2 Setup for SI engine testing

5. 5
5. Conclusion
Biogas appears to be a feasible fuel for
internal combustion engines because it can be
derived from agricultural surpluses and residues,
which provide the raw material for biogas
production. By feeding the byproduct of the biogas
production process, a farmer may even incorporate
the production of his own fuel as an integral part of
the food production system.
Biogas for power generation has been
recognized as an important component of the
renewable energy program in India. Biogas
collection and storage of biogas are the most
serious constraints in the widespread utilization of
this resource for I.C. engine. From the performance
test it can be seen that mass flow rate is varies for
the various load condition. Also the percentage of
CO conditions when both fuels are used. From the
performance test can be concluded that the mass
flow rate of Bio-Gas is more as compare to the
L.P.G. for same operating conditions .at the
maximum load conditions the mass flow rate
greater for Bio-Gas as compared to the L.P.G. The
motivation is that for present work is systematic
study of engine performance with 100% biogas
operation. The use of biogas injection close to the
intake manifold for biogas involved higher
volumetric efficiency than the conventional
method of premising air and biogas commonly
used for biogas operation. The higher volumetric
efficiency of engine however did not result in any
gain in performance. The reason for this was a low
compression ratio of engine.
5.1 Future scope
Power generation in India was only 4.1
billion kWh in the year 1947-48 and in the year
2002-03 it was more than 600 billion kWh. Now it
is up to 900 billion. considering the past record, the
future economy growth scenario and likely boost to
captive. This animal wealth produces about 37
million kg animal dung, which has potential of
producing about 1.2 million cubic meter bio-gas.
This huge amount can suffice the cooking fuel
requirement of about 50 lacks families. Power
plant sector as a result of changes arising due to
Electricity Act 2003, the target of generating about
8000 billion kWh per year by 2042 is achievable.
In only Maharashtra State enriched livestock
population of about 18.3 million.
6. References
1. Singh. A., “Conversion of a 1.2 kW Genset
for 100% biogas operation”.
2. Jawuerk, H. H., Lane, N. W., Rallis,
“Biogas/petrol dual fuelling of SI engine
for rural third use”,
3. Karim, G.A., “Combustion in gas fueled
compression ignition engines of the dual-
fuel type”, Journal of Engineering Gas
Turbines and Power, July 2003,
4. Badr, O, Karim, G.A., Liu, B., “An
examination of flame spread limits in a dual
fuel engine”,
5. Mitzlaff, Klaus von, “Engines for Biogas”,
A publication of Deutsches Zentrum fűr
Entwicklungstechnologie
6. V. Ganeshan, Internal Combustion Engines,
second edition.