About Compressed Natural Gas (CNG)

2. CONTENTS
 Preparation
 Importance
 Advantages
 Disadvantages
 Effects
 Conclusion

3. CNG FUEL
CNG- compressed natural gas.
It is substitute fossil fuel for
DIESEL,PETROL,PROPANE.

4. LOGOS FOR CNG

5. PREPARATION
It is made by compressing the natural gas(composed of
methane) to less than 1% of the volume at standard
atmospheric pressure .It is stored in hard cylindrical containers
at a pressure of 200-280 bars.

6. Schematic diagram for biogas to biomethane (CNG)
conversion
Fig: Air and gas process technology

7. AVAILABILITY OF CNG
 The world’s largest gas field is the offshore Gas-Condensate
field, shared between Iran and Qatar.It is estimated to have 51
trillion cubic meters of natural gas and 50 billion barrels of
natural gas condensats.
 The areas which are high in natural gas availability in India are
mostly the Western offshore area.
 The other major production areas for natural gas are the on-
shore fields in Assam,Andhra Pradesh and Gujarat states,
 Natural gas in comparatively lesser amount is also produced in
the states of Tripura,Tamil Nadu and Rajasthan states.

8. CONSTITUENT PERCENTAGE LIMIT
Methane 90% Maximum
Ethane content 4% Maximum
Propane content 1.7% Maximum
C4 and higher 0.7% Maximum
C6 and higher 0.2% Maximum
CO2+N2 0.2% Maximum
Hydrogen 0.1% Maximum
Carbon Monoxide 0.1% Maximum
Oxygen 0.5% Maximum
Sulfur 10ppm Maximum

9. IMPORTANCE
It is cheap than other fuels.
It is dispersed quickly when released.
It is lighter than air.
It releases less carbon into the atmosphere.

10. WHY USE CNG ENGINE?
 An engine running on petrol for 100 km emits 22,000 grams of
C𝑂2,for same distance on the other hand CNG emits only
16,275 grams of C𝑂2.
 It burns with oxygen to produce 1 mole of C02 and 2 moles of
𝐻2O.By comparison,petrol is essentially 𝐶6 𝐻6 with a calorific
value of 3,300 kJ/mol and this burns to produce 6 moles of
C𝑂2 and 3 moles of 𝐻2 𝑂.So it gives less pollution.

11. THE CNG ENGINE
 THE CNG engine uses a second fuel tank which has to be
attached to the car, and is usually placed in the trunk or
other suitable place.
 This tank is usually very large, as it has to keep the gas
used compressed . The amount of pressure may vary from
engine to engine but is usually compressed around 3,600
pounds per sq. inch.
 The driver can then decide which of the fuels to they wish
to use by simply pressing the switch on the dashboard.
 Thus, car can alternate between the different tanks,
drawing fuel from either.

12. CNG ENGINE

13. HOW THE CNG ENGINE POWERS THE CAR
Once the driver selects the CNG tank, the compressed gas in
the tank is pulled through a series of highly pressurized lines
until it reaches the regulator. Inside the regulator, the
pressure on the gas is lessened until it matches the amount
needed by the fuel injection system if the car’s engine. Once
the gas has reached an acceptable pressure, the solenoid
valve allows the gasto move into the fuel injection system
and from there into the engine. Just as with gasoline, once
the engine has received the gas, it is ignited in the
combustion chamber and this provides the energy to power
the car forward.

14. COMPARISION OF PROPERTIES OF CNG WITH GASOLINE
Properties Gasoline CNG
Stoichiometric ratio 14.2 15.7
Octane number 96 120-130
Higher heating value(MJ/kg) 45 50.3
Lower heating value(MJ/kg) 42.2 45.9
Molecular weight 106.2 16
Minimum ignition energy(MJ) 0.33 0.26
Laminar flame speed(cm/sec) 30 37.5
Flammability limits(Vol% in
air)
5.2 15.6
Adiabatic Flame Temp(K) 2227 2266

15. COMPARISION OF PRICES
In India price of fuels vary for different reigons. For example,
according to recent updates prices of fuels in our capital DELHI
is :
• Petrol-70.28 Rs/Ltr
• Diesel-58.6 Rs/Ltr
• CNG-38 Rs/Kg

16. MAINTENANCE
Proper training is required for maintenance purpose on
CNG vehicles. The oil in the CNG vehicles does not need to
be changed as frequently because CNG burns more cleanly
than gasoline, producing less deposits in the oil.

17. USES
 CNG is used in many vehicles like bikes and cars
 It is also used in commercial vehicles light duty truck and
medium duty truck like vans and postal vehicles and
school buses.

18. SUCCESS OF CNG
CNG Cars:
• Manufacturers –Fiat, Opel, Volkswagon, Toyota, Honda
etc sell bi-fuel cars.
• In 2006, Fiat introduces the ‘SIENA’ which was tetra fuel
car in Brazilian market which contained CNG.
CNG Locomotives:
• “The Napa Valley Wine Train” was first locomotive to run
on CNG before 2002.

20. ADVANTAGES
 Environment Friendly
 Low maintenance cost than other vehicles
 Increases the life of lubricating oil
 It mixes easily and evenly in air
 Less pollution and more efficiency
 It is cheaper than petrol and diesel

21. DISADVANTAGES
 It requires high storage space
 CNG filling stations have limited availability as compare
to gasoline
 They are low power engine than the gasoline engine

22. CONCLUSION
 Due to above reasons CNG is most useful for vehicles as a
fuel to reduce the pollution and it is cheap than other fuels
like petrol and diesel.
 It is clean and safe.
 Produces lower air pollution