Comparison between CNG & LPG

1. Engr. Mohammad Imam Hossain Rubel, Email: rubelduet04@gmail.com , Skype: mdimam
Comparison between CNG & LPG
Objects CNG LPG
Constituents Methane CH4 Propane and Butane C3H8 C4H10
Source Obtained from natural gas-and-
condensate wells, oil wells, coal bed
methane wells.
Automatically generated from gas fields
when natural gas is extracted from the
reservoir. By-product of cracking process
during crude-oil refining.
Uses Substitute for gasoline in automobiles. Heating and cooking in homes,
refrigeration, industrial, agricultural,
catering and automobile fuel.
Environmental
effects
Releases lesser greenhouse gas. Releases CO2 which is a greenhouse gas
but is cleaner when compared to
gasoline
Properties It is lighter than air and hence disperses
quickly in the event of spillage.
Highly inflammable. It is heavier than air
and on leakage will settle to ground and
accumulate in low lying areas.
Stored Pressure 200 to 248 bars 1.7 - 7.5 bar
Safety Easily disperses, hence risk of ignition is
minimized.
Since it is difficult to disperse risk of fire
is more.
Energy Produced 38 MJ/m3 or 10.6 kWh/m3 94 MJ/m3 or 26.1kWh/m3
Safety and
Environmental
Impact
CNG does produce greenhouse gases
upon combustion; it is a more
environmentally clean alternative to
other fossil fuels like gasoline or LPG.
CNG is also safer than other fuels in the
event of a spill because natural gas, being
lighter than air, disperses quickly when
released.
Storage Little more space need Need Lesser Space
For proper
Combustion Air to
Gas ratio
Approximately 10:1 Approximately 25:1
Relative density
with air
0.5537:1 1.5219:1
Auto Ignition
Temp.
540C 455 to 510C
Flammability
Range
5-15% 2-9.5%
Auto Mileage Same number of Mileage of gasoline About 28% fewer mileage than of
gasoline
Carbon Emission (H:C>4:1)Lesser carbon Emission than
any other fossil Fuel
(H:C>8:3/10:4) cleaner fossil fuel than
gasoline & diesel