Natural gas is known as an alternative fuel for the transportation sector. Based on the research done by the Natural Gas Vehicle Coalition, there are currently 120,000 Natural Gas Vehicles (NGVs) on the road in the United States today, and more than 8.7 million NGVs worldwide. The transportation sector depends on natural gas as their key fuel, and there are about 1,100 natural gas fueling stations in the U.S. alone. Technology has also improved in recent years allowing a proliferation of natural gas vehicles, particularly for fuel intensive vehicle fleets such as cabs and public buses. However, all types of natural gas vehicles today are a production for either sale to the public or in development from cabs, trucks, vans, buses and even heavy-duty utility vehicles.
Besides these advances, there are also a number of disadvantages of NGVs which prevents their mass-production such as limited range, higher initial cost, trunk space and lack of refueling infrastructure. Disadvantages such as this tend to pose impediments to the spread of natural gas vehicles in the near future. Most natural gas vehicles are operated using compressed natural gas (CNG). This compressed gas is stored in a vehicle’s gasoline tank which is attached to the rear, top, or undercarriage of the vehicle in a tube shaped storage tank. A CNG tank could be filled in the same way and also filled in a similar amount of time, to a gasoline tank.
In addition, there are several components in an NGV which requires modification so that the engine would be able to run efficiently on natural gas. Besides using CNG, there are also some natural gas vehicles that are fueled by Liquefied Natural Gas (LNG). Many natural gas vehicles that exist today are of bi-fuel vehicles. These vehicles could use gasoline or natural gas which allows more flexibility in fuel choice and had also been converted to allow the vehicle to run on either fuel. However, this conversion is rather costly which results in less efficient use of natural gas in transportation.