- Natural gas is one of the cleanest burning alternative fuels available and offers a number of advantages over gasoline.
- Primary applications for NGVs are transit buses, taxicabs, garbage trucks, and other fleet vehicles.
- NGVs have a lower operating cost and environmental profile than traditional gasoline-fueled vehicles.
Fleet managers are always looking for ways to cut costs, and natural gas vehicles (NGVs) are an excellent option in many applications. According to the most recent Alternative Fuel Price Report
published by the U.S. Department of Energy (DOE), the compressed natural gas (CNG) price is significantly less than gasoline and diesel on an energy equivalent basis—$2.10 versus $3.29 and $3.55, respectively. The U.S. Energy Information Administration reports that natural gas is expected to cost 50 percent less by 2035. Because NGVs also run on domestically produced natural gas, dependence on foreign oil is reduced.
There are 112,000 NGVs on U.S. roads today and over 13 million worldwide, according to NVGAmerica. The International Association of Natural Gas Vehicles estimates that there will be more than 50 million natural gas vehicles worldwide within the next 10 years—about 9 percent of the world transportation fleets.
Natural gas is one of the cleanest burning alternative fuels available and offers a number of advantages over gasoline. In light-duty applications, air exhaust emissions are much lower in NGVs than gasoline-powered vehicles. In addition, smog-producing gases, such as carbon monoxide and nitrogen oxides, are reduced by up to 90 percent and 95 percent, respectively. Carbon dioxide, a greenhouse gas, is reduced by up to 30 percent. (NVGAmerica)
For heavy-duty and medium-duty applications, natural gas engines have demonstrated more than a 90 percent reduction of carbon monoxide and particulate matter and more than a 50 percent reduction of NOx relative to commercial diesel engines.
While the number of natural gas fueling stations is growing, availability is still limited in some areas. This makes natural gas fuel most practical in fleet vehicles. Fleets generally operate a large number of vehicles fueled in a central location. In fact, many of the natural gas fueling stations that currently exist are private fueling stations for individual fleets. Fleet vehicles also travel more miles per day than the average personal vehicle, allowing them to take greater advantage of the lower fuel costs.
While transit buses (62 percent of all vehicular natural gas use) and taxicabs have led the market in NGV fleet applications, natural gas is growing in a number of other areas including school buses, airport shuttles, forklifts, street sweepers and refuse haulers. Waste collection and transfer vehicles, which account for about 12 percent of total vehicular natural gas use, are the fastest-growing NGV segment.
How NGVs work
NGVs operate essentially the same way as traditional gasoline-powered cars and trucks. A fuel and air mixture enters a cylinder and is ignited by a spark plug where it moves a piston up and down. Most NGVs operate on compressed natural gas (CNG) to save space, although liquefied natural gas (LNG) can also be used. Natural gas can fuel any vehicle currently powered by gasoline or diesel. However, given that natural gas is a gas and not a liquid, some modifications are required to enable NGVs to function efficiently. Most of these modifications are in the fuel storage tank, the fuel receptacle, and the engine.
NGVs that run on compressed natural gas (CNG) require special high-pressure storage cylinders attached to the rear, top or underside of the vehicle. Since CNG is a gaseous product, the fuel receptacle must be a leak-free seal, similar to an air compressor nozzle. Natural gas engines also include a regulator to decrease pressure. While many vehicles are manufactured and sold as NGVs, conventional vehicles can be converted to run on natural gas.
Fueling a NGV
Nearly 1300 natural gas fueling stations are operating in the United States, according to the U.S Department of Energy's Alternative Fueling Station Locator. Many of these are privately owned and used exclusively for fleet vehicles, but about half of them are open to the public.
Cost and maintenance
NGVs generally cost more than similarly sized gas- or diesel-powered vehicles. However, the improved environmental performance and the lower operating costs have made NGVs an attractive option. NGVs can cost less to operate than gasoline- or diesel-fueled vehicles, depending on natural gas prices.
Purchase prices for NGVs are somewhat higher than for similar conventional vehicles. The auto manufacturers' typical price premium for a light-duty CNG vehicle can be $1,500 to $6,000, and for heavy-duty trucks and buses, it is in the range of $30,000 to $50,000.
The U.S. ARPA-E recently announced $30 million in funding for a new program, Methane Opportunities for Vehicular Energy (MOVE). This program will fund projects to develop lightweight NG tanks that fit into modern passenger vehicles and technologies to lower pressure in vehicle tanks, making them safer and more affordable.
Where can I get NGV equipment and accessories?
Currently, there is limited availability of natural gas vehicles for passenger cars and other light-duty vehicles. The Honda Civic GX NGV is available in certain parts of the country, and Chevrolet and GMC are building bi-fuel Chevrolet Silverado and GMC Sierra 2500 HD extended cab pickup trucks. Chrysler plans to start selling CNG vehicles by 2017, and Dodge plans to manufacture a factory-built Ram CNG pickup truck in the near future.
Conventional light-duty vehicles can be converted to run on natural gas. For conversion equipment providers, see the U.S. Department of Energy's Conversion Industry Company Contacts database. To locate suppliers of NGVs, engines, conversion kits, and fueling station equipment, see the Resource Directory available on the NGVAmerica website.
Clean Cities Alternative Fuel Price Report, January 2013, accessed May 7, 2013.
NGVAmerica (Natural Gas Vehicles for America), accessed March 6, 2012.
The content of this article, including pricing information, was current and accurate at the time the article was written.