Liquefied petroleum gas, compressed natural gas industrial applications

Liquefied petroleum gas Vs Compressed natural gas


Development of any region in the world mainly depends on the transportation.

The basic infrastructures required for the region’s economic growth are roads, railways, and water and air connectivity.

A drastic change in globalization and liberalization policies of the government has led to increased urbanization and concentrated economic activities in certain load centers resulting in higher mobility.

Global automobile production by year wise

Energy consumption also varies with the modes of transport.

Energy consumption also varies with the modes of transport.

  • Coal
  • Diesel
  • Petroleum (gasoline)
  • Electricity
  • Biofuels
  • LPG and
  • CNG

Increase in the use the of different energy sources in vehicles is leading to the emission of different types of gases into the environment.

The following table shows the various types of vehicles emitting a different type of gases into the environment.


To reduce releasing of harmful gases into the environment vehicles need to be used following types of gases as their fuels

LPG [Liquefied Petroleum Gas]

CNG [Compressed Natural Gas]

Liquefied Petroleum Gas

LPG is a non-renewable source of energy. It is extracted from crude oil and natural gas. The main composition of LPG is hydrocarbons containing three or four carbon atoms.

The normal components of LPG are:

Propane (C3H8) and

Butane (C4H10)

LPG is a gas at atmospheric pressure and normal ambient temperatures, but it can be liquefied when moderate pressure is applied or when the temperature is sufficiently reduced. It can be easily condensed, packaged, stored and utilized, which makes it an ideal energy source for a wide range of applications.

Liquid petroleum gases were discovered in 1912 when Dr. Walter Snelling, an American scientist, realized that these gases could be changed into liquids and stored under moderate pressure. Between 1912 and 1920, LP-gas uses were developed. The first LPG cook stove was made in 1912, and the first LPG -fueled car was developed in 1913. The LPG industry began sometime shortly before World War I.

LPG can be used as a power source for combined heat and power technologies (CHP), used to fuel internal combustion engines, refrigeration process and as cooking fuel.

Compressed Natural Gas

CNG is a fossil fuel substitute for gasoline (petrol), diesel, or propane/LPG.

It is a more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill (natural gas is lighter than air, and disperses quickly when released). CNG may also be mixed with biogas, produced from landfills or wastewater, which doesn't increase the concentration of carbon in the atmosphere.

CNG is made by compressing natural gas (which is mainly composed of methane [CH4]), to less than 1% of the volume, it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 200-248 bar (2900-3600 psi).

CNG emits significantly fewer pollutants such as

  • Carbon dioxide (CO2)
  • Unburned hydrocarbons (UHC)
  • Carbon monoxide (CO)
  • Nitrogen oxides (NOx)
  • Sulfur oxides (SOx) and
  • Particulate matter (PM)


CNG vehicles emit 40 percent less of nitrous oxide (a toxic gas that creates smog), 90 percent less of hydrocarbons (which carry carcinogens), 80 percent less of carbon monoxide (a poisonous pollutant), and 25 percent less of carbon dioxide (a major greenhouse gas).

Global usage of CNG

Pakistan – Pakistan leaves behind Argentina to top the countries running the highest number of vehicles on compressed natural gas (CNG) and also having the highest number of CNG refueling stations.

The number of CNG-run vehicles had gone up to over 2.4 million, whereas the number of CNG stations stood at 3,105.

Argentina - It is the only country in the world to have converted over 6 lakh vehicles to CNG and is presently converting 3000 vehicles every year to CNG.

US - The US has 87,500 vehicles running on NG with 40% of the total number of CNG refueling stations in the world.


Italy & Germany has 800 CNG stations

Bulgaria has 96 CNG stations

Sweden has ~14500 CNG vehicles

Top ten countries with most CNG vehicles

Country Consumption [in millions]
Iran 2.86
Pakistan 2.85
Argentina 2.07
Brazil 1.7
India 1.1
Italy 0.78
China 0.61
Colombia 0.36
Uzbekistan 0.31
Thailand 0.30










Advantages and Disadvantages

LPG advantages

  • LPG is cheaper than petrol (up to 50%)
  • It produces fewer exhaust emissions than petrol
  • It is better for the engine and it can prolong engine life
  • Is non-poisonous and safe to use
  • Potentially lower toxic, carbon dioxide (CO2), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions


LPG disadvantages

  • Less readily available than gasoline & diesel
  • The initial cost for converting the vehicle to LPG is expensive.
  • It has a lower energy density than petrol
  • No new passenger cars come readily fitted with LPG (they have to be converted)
  • Fewer miles on a tank of fuel


CNG advantages

  • Natural gas is significantly less expensive than gasoline.
  • CNG is more eco-friendly than gasoline.
  • Natural gas produces far fewer harmful emissions and hydrocarbons than gasoline.
  • Using CNG makes the engine cleaner and more efficient.
  • CNG makes the engine run quieter. Because of the higher octane levels of natural gas, the engine runs quieter resulting to minimized engine nose.


CNG disadvantages

  • CNG tanks require storage space
  • CNG Filling stations have limited availability
  • Lack of knowledge on CNG usage
  • Additional cost involved in CNG utilization in vehicles











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