Natural gas was first used to fuel vehicles in the 1930s and has long been considered an alternative fuel for the transportation sector.

According to NGV Global (formerly known as The International Association for Natural Gas Vehicles – IANGV, and the leading authority on natural gas vehicles), in 2010 there are over 12 million vehicles operating on natural gas. In recent years, technology has improved to allow for a proliferation of natural gas vehicles (NGV), particularly for fuel intensive vehicle fleets, such as taxicabs and public buses.
Most NGVs operate using compressed natural gas (CNG). This compressed gas is stored in similar fashion to a car’s gasoline tank, attached to the rear, top, or undercarriage of the vehicle in a tube shaped storage tank. A CNG tank can be filled in a similar manner, and in a similar amount of time, compared to a gasoline tank.

This natural gas fuels a combustion engine similar to engines fueled by other sources. However, in a NGV, several components require modification to allow the engine to run efficiently on natural gas. In addition to using CNG, some NGVs are fueled by Liquefied Natural Gas (LNG). Some NGVs that exist today are bi-fuel vehicles, meaning they can use gasoline or natural gas, allowing for more flexibility in fuel choice. Many of these vehicles, which were originally gasoline only, have been converted to allow the vehicle to run on either fuel.