VEHICLE TECHNOLOGIES PROGRAM Natural Gas Basics Natural gas powers more than 100,000 vehicles in the United States and roughly 11.2 million vehicles worldwide.1 Natural gas vehicles (NGVs) are a good choice for high-mileage fleets—such as buses and taxis—that are centrally fueled or operate within a limited area. The advantages of natural gas as an alternative fuel include its domestic availability, widespread distribution infrastructure, low cost compared with gasoline and diesel, and clean-burning qualities. What is natural gas? cooking; one-third to industrial uses; and PIX 16724 one-third to electric power production. Natural gas is an odorless, nontoxic, Compressed natural gas is stored Only about one-tenth of 1% is used for gaseous mixture of hydrocarbons—pre- onboard a vehicle in safe, puncture- transportation fuel. resistant tanks. dominantly methane (CH4). Because it is a gas, it must be stored onboard a vehicle in either a compressed gaseous or lique- Is natural gas safe for use fied state. Compressed natural gas (CNG) in vehicles? the latest new vehicle offerings, also see the AFDC’s light-duty and heavy-duty is typically stored in a tank at a pressure Yes. NGVs meet the same safety stan- vehicle searches. of 3,000 to 3,600 pounds per square inch. dards as gasoline and diesel vehicles and Liquefied natural gas (LNG) is super- also meet the National Fire Protection cooled and stored in its liquid phase at Association’s (NFPA) NFPA 52 How do NGVs work? -260°F in special insulated tanks. Natural Vehicular Fuel System Code. Natural gas NGVs operate in one of three modes: gas is sold in units of gasoline or diesel has a narrow flammability range and, dedicated, bifuel, or dual-fuel. Dedicated gallon equivalents based on the energy because it is lighter than air, dissipates NGVs run on only natural gas. Bifuel content of a gallon of gasoline or diesel quickly if released. NGV fuel tanks are NGVs can run on either natural gas or fuel. strong and extremely puncture resistant. gasoline. Dual-fuel vehicles run on natu- How and where is ral gas and use diesel for ignition assist. What NGVs are available? Light-duty vehicles typically operate in natural gas produced dedicated or bifuel modes, and heavy- A wide variety of new, heavy-duty NGVs and distributed? duty vehicles operate in dedicated or are available. The Honda Civic GX is Natural gas is drawn from wells or dual-fuel modes. extracted in conjunction with crude oil the only light-duty NGV available from production. Biomethane, a renewable a U.S. original equipment manufacturer A CNG fuel system transfers high-pres- form of natural gas, is produced from (OEM). Consumers and fleets also have sure natural gas from the storage tank to decaying organic materials, such as waste the option of economically and reliably the engine while reducing the pressure from landfills, wastewater, and livestock. converting existing light- or heavy-duty of the gas to the operating pressure of In recent years, 80% to 90% of the natural gasoline or diesel vehicles for natural the engine’s fuel-management system. gas used in the United States was pro- gas operation using certified installers. The natural gas is injected into the duced domestically. The United States See the Conversions page in the Vehicles engine intake air the same way gasoline has a vast natural gas distribution system, section of the Alternative Fuels and is injected into a gasoline-fueled engine. which can quickly and economically dis- Advanced Vehicles Data Center (AFDC) The engine functions the same way as a www.afdc.energy.gov. tribute natural gas to and from almost any Web site at For gasoline engine: The fuel-air mixture is location in the lower 48 states. compressed and ignited by a spark plug and the expanding gases produce rota- How is natural gas used? tional forces that propel the vehicle. Natural gas accounts for about a quarter On the vehicle, natural gas is stored in of the energy used in the United States. tanks as CNG, or in some heavy-duty About one-third goes to residential and commercial uses, such as heating and 1 NGV Communications Group (www.ngvgroup.com) www.cleancities.energy.gov • April 2010 VEHICLE TECHNOLOGIES PROGRAM • April 2010 • Page 2 vehicles, as LNG, a more expensive $5.00 option. The form chosen is often depen- dent on the range a driver needs. More natural gas can be stored in the tanks as $4.00 LNG than as CNG. $3.00 How do NGVs perform? Natural gas vehicles are similar to $2.00 gasoline or diesel vehicles with regard to per GGE Cost power, acceleration, and cruising speed. The driving range of NGVs is generally $1.00 less than that of comparable gasoline and diesel vehicles because, with natural gas, less overall energy content can be $0.00 stored in the same size tank as the more Jul-06 Jul-07 Jul-08 Jan-06 Jan-07 Jan-08 Jan-08 Sep-05 Sep-06 Sep-07 Sep-08 energy-dense gasoline or diesel fuels. Mar-06 Mar-07 Mar-08 Mar-08 Nov-05 Nov-06 Nov-07 Nov-08 May-06 May-07 May-08 Extra natural gas storage tanks or the use Gasoline Diesel CNG of LNG can help increase range for larger vehicles. Figure 1. Nationwide Average Retail Gasoline, Diesel, and Natural Gas Prices In heavy-duty vehicles, dual-fuel, com- stable—than the price of gasoline and proper safety precautions must be taken pression-ignited engines are slightly more diesel (see Figure 1), which makes natural when refueling NGVs. fuel-efficient than spark-ignited dedicated gas a good option for fleets that use a lot natural gas engines. However, a dual-fuel of fuel. Incentives are also available to How do NGV emissions engine increases the complexity of the reduce the cost of operating NGVs. fuel-storage system by requiring storage compare with gasoline and of both types of fuel. Where is natural gas diesel vehicle emissions? How much do NGVs cost? available? Compared with gasoline and diesel Light-duty NGVs cost $5,000 to $7,000 vehicles, NGVs can produce significantly According to the AFDC, there were lower carbon monoxide, nitrogen oxide, more than comparable gasoline vehicles, 827 CNG and 38 LNG stations in the and heavy-duty NGVs cost more than nonmethane hydrocarbon, particulate United States as of February 2010. To matter, and other toxic emissions, as well their counterparts by $30,000 or more. find natural gas station locations, visit the The price depends on the fuel-tank capac- as greenhouse gas emissions. In addition, Alternative Fueling Station Locator at because CNG fuel systems are com- ity and whether the vehicle is produced www.afdc.energy.gov/stations. by an OEM or converted to run on natural pletely sealed, CNG vehicles produce no gas. However, government incentives are evaporative emissions. For details, see the available to offset NGV costs. For more Is it easy to fuel an NGV? Natural Gas Vehicle Emissions page in www. information, visit the AFDC’s Incentives Yes. CNG vehicles are fueled with easy- the Vehicles section of the AFDC at afdc.energy.gov and Laws section at www.afdc.energy.gov. to-use, pressure-sealed dispensers. CNG . Due in part to the high octane rating and fueling stations can be configured to fuel clean-burning properties of natural gas, vehicles at various rates. Time-fill stations Where can I learn more some fleets have reduced maintenance fuel parked vehicles overnight, taking about natural gas? and operating costs for NGVs compared advantage of off-peak electricity rates To learn more about natural gas as a trans- with conventional vehicles. and smaller compression equipment. portation fuel, visit the AFDC’s natural Fast-fill stations fill vehicles rapidly gas pages at www.afdc.energy.gov. The using larger compression equipment How much does natural NGV America Web site at www.ngvc.org and high-pressure gas-storage systems. also features a wealth of information about gas cost? Fueling LNG vehicles requires special natural gas and NGVs. Historically, the average retail price of procedures and training, but the process natural gas has been lower—and more is not difficult. As with all vehicles, EERE Information Center Prepared by the National Renewable Energy Laboratory 1-877-EERE-INF (1-877-337-3463) (NREL), a national laboratory of the U.S. Department of www.eere.energy.gov/informationcenter Energy, Office of Energy Efficiency and Renewable Energy; NREL is operated by the Alliance for Sustainable Energy, LLC. Printed with a renewable-source ink on paper containing at least 50% wastepaper, DOE/GO-102010-3068 • April 2010 including 10% post consumer waste..