Natural Gas

Information on the superior safety characteristics of natural gas can be found here.

The natural gas used for Natural Gas Vehicles (NGVs) is the same as that piped to millions of homes for cooking and heating.

Molecularly, natural gas is a very simple fuel. Around 90% of natural gas is methane (CH4), which is just one carbon atom with four hydrogen atoms attached, with the remainder comprising of propane, butane and other components. Composition varies according to the source of the natural gas.

The only simpler fuel available is hydrogen, which is technically an energy ‘carrier’ rather than an energy source itself. As yet there is no economic method of creating and distributing large quantities of hydrogen, so, until this occurs, natural gas will remain the clean fuel of choice for some time. Being rich in hydrogen, natural gas is often used as a feedstock, which is one of the reasons why natural gas vehicles are often referred to as the ‘pathway to the hydrogen economy’. Ultimately, an investment in natural gas infrastructure is an investment in hydrogen infrastructure.

Natural gas occupies more volume than traditional liquid fuels thus it must be compressed or liquefied to make it practical for transport applications. Compressed Natural Gas (CNG) is the most common application for NGVs though Liquefied Natural Gas (LNG) use is becoming increasingly common. More details on the different processes can be found on the refuelling page.

When comparing fuel prices it is important to consider energy content of fuels. CNG is sold either by the kilogram or the cubic meter (m3) and LNG is measured in litres. A cubic metre of natural gas contains approximately 38.3* megajoules per cubic metre (MJ/m3), which is approximately the same amount of energy as a litre of diesel (38.8* Mj/l). In some countries, CNG or LNG is sold by the Gasoline per Gallon Equivalent (GGE) or Diesel per Gallon Equivalent (DGE). In these cases the energy content has already been taken into account so the fuel price comparison can be made directly.

Fuel CNG LNG Diesel Gasoline LPG
Energy Content*
(Gross heating value)
37-40 MJ/m3
46-49 MJ/kg
25 MJ/L 38.3 MJ/L 34.5 MJ/L 25.4 MJ/L

* Energy content varies significantly depending on the source of fuel. Readers are advised to check with local suppliers for energy content.