What NGVs are available? A wide variety of new, heavy-duty NGVs are available. The Honda Civic GX is the only light-duty NGV available from a U.S. original equipment manufacturer (OEM). Consumers and fleets also have the option of economically and reliably converting existing light- or heavy-duty gasoline or diesel vehicles for natural gas operation using certified installers. See the Conversions page in the Vehicles section of the Alternative Fuels and Advanced Vehicles Data Center (AFDC) Web site at www.afdc.energy.gov. For the latest new vehicle offerings, also see the AFDC's light-duty and heavy-duty vehicle searches.
How do NGVs work? NGVs operate in one of three modes: dedicated, bifuel, or dual-fuel. Dedicated NGVs run on only natural gas. Bifuel NGVs can run on either natural gas or gasoline. Dual-fuel vehicles run on natural gas and use diesel for ignition assist. Light-duty vehicles typically operate in dedicated or bifuel modes, and heavy-duty vehicles operate in dedicated or dual-fuel modes.
A CNG fuel system transfers high-pressure natural gas from the storage tank to the engine while reducing the pressure of the gas to the operating pressure of the engine's fuel-management system. The natural gas is injected into the engine intake air the same way gasoline is injected into a gasoline-fueled engine. The engine functions the same way as a gasoline engine: The fuel-air mixture is compressed and ignited by a spark plug and the expanding gases produce rotational forces that propel the vehicle.
On the vehicle, natural gas is stored in tanks as CNG, or in some heavy-duty vehicles, as LNG, a more expensive option. The form chosen is often dependent on the range a driver needs. More natural gas can be stored in the tanks as LNG than as CNG.