Uneven Prospects For Natural-Gas Vehicles

Aug. 10, 2010
Natural-gas vehicles lessen America’s dependence on imported oil, run clean, and cost less to operate, compared to conventional vehicles. But only one major automaker sells them in the U. S., they’re difficult and costly to retrofit, and fueling stations are few and far between
Available NGVs and retrofits, tinyurl.com/2f6yzyn
Clean Vehicle Education Foundation, cleanvehicle.org
DOE’s list of alternative fueling stations, tinyurl.com/262rl9v
ECO Friendly LLC, www.ecofriendlyllc.com
Honda GX, automobiles.honda.com/civic-gx
Impco Technologies, www.impcotechnologies.com
Natural Drive Partners, www.naturaldrive.com
Natural–gas-vehicle forum, www.cngchat.com
NGVAmerica, www.ngvamerica.org
Office of Energy Efficiency and Renewable Energy, www.eere.energy.gov
The Pickens Plan, www.pickensplan.com

Everyone from President Obama to T. Boone Pickens says America needs cars that are clean, economical, and run on alternative fuels. Natural-gas vehicles (NGVs) seem to fit the bill.

After all, there’s a lot to like about natural gas as a transportation fuel. From a national-security standpoint, it lessens America’s dependence on imported oil. The U. S. currently imports more than 60% of the oil it uses, but nearly 98% of our natural gas comes from North America. Supplies are ample, and new drilling techniques are opening previously untapped reserves.

Increasingly stringent federal and state regulations are forcing vehicle manufacturers to reduce emissions. Natural gas, however, is the cleanest-burning, commercially available transportation fuel. Per unit of energy, it also contains less carbon than other fossil fuels. And it’s around 90% methane, which produces only CO2 and water when it burns.

Thus, emissions from NGVs are significantly lower than those from gasoline and diesel-powered vehicles. Estimates from the U. S. Environmental Protection Agency (EPA) are that NGVs produce 20 to 30% fewer greenhouse gases than conventional vehicles, reduce NOx emission by 35 to 60%, and carbon monoxide by up to 97%. Natural-gas combustion also produces fewer carcinogens and virtually no particulates.

For drivers, natural-gas refueling costs are about one-third less than that for gasoline — with potentially greater savings if refueling at home. And buyers of NGVs and home-refueling devices are often eligible for federal or state tax credits worth several thousand dollars. Equally important, there is reportedly little difference in acceleration, mileage, and performance between natural gas and similar gasoline-powered vehicles. And some states permit NGVs to use HOV lanes.

Reality check
Yet despite the benefits, there are only about 110,000 NGVs on U. S. roads today, according to NGVAmerica, a Washington D.C.-based organization dedicated to developing natural-gas and hydrogen-powered vehicles. About two-thirds of these are transit buses, and most of the rest are refuse vehicles and private fleets. Options for consumers are scarce, to say the least.

For instance, don’t expect to run down to your local car dealer and pick up an NGV. Currently, the Honda Civic GX is the only new NGV for sale to consumers in the U. S., and it’s only available at select dealers in four states — California, New York, Oklahoma, and Utah.

The 2010 GX retails for $25,340, a $6,830 premium over the gasoline-powered Civic LX. (However, this can be partially offset by a $4,000 federal-tax credit.) Both have 1.8-liter, four-cylinder aluminum engines, but there are subtle differences. Rated horsepower for the GX is 113 hp @ 6,300 rpm versus 140 @ 6,300 for the LX; torque of 109 lb-ft @ 4,300 rpm for the GX compares to 128 lb-ft @ 4,300 rpm for the LX; and compression ratios are 12.5:1 and 10.5:1 for the GX and LX, respectively. Mileage ratings are nearly identical. The GX gets 24-mpg city and 36-mpg highway, with the LX a slightly better 25/36 mpg.

Probably the most noticeable differences lie in cargo and fuel capacities. The conventional LX has 12 ft3 of storage space but the NGV GX only half that due to larger fuel tanks. Also, the LX has a 13.2-gallon gas tank, while the GX’s fuel capacity is 7.8 gasoline-gallon equivalents (GGE) at 3,600 psi. Obviously, that equates to a shorter driving range before refueling.

Conversion options
Another option for consumers is to retrofit conventionally powered cars, but that carries its own headaches. First the EPA governs the manufacture and installation of alternative-fuel engine-conversion systems. The California Air Resources Board (CARB) has similar rules for that state. Only certified conversion kits can be legally installed. Although a variety of noncertified kits are available, the EPA considers the installation of such systems to be tampering with approved emission controls, punishable with a substantial fine.

Obtaining certification is expensive and arduous, so conversion kits are only available for a limited number of engines and vehicles. (See the Resources box for a current list.)

Then there’s the cost. Converting a vehicle to run on natural gas includes the expense of components such as regulators, cylinders, tubing, and brackets, as well as costs for installation and software programming. For instance, Natural Drive Partners of Goodyear, Ariz., quotes an approximate price of $11,000 to $13,000 to convert a Chevrolet Impala with a fuel capacity of 10.4 to 13 GGE. Typically, new vehicles are the best candidates for conversion, as they provide the greatest opportunity to recoup costs through fuel savings.

Also note that compressed-natural-gas (CNG) cylinders, often the most-expensive component in the fuel system, must meet Dept. of Transportation standards. They need to be inspected every three years or 36,000 miles. And they carry an expiration date, after which they should be replaced (typically in 15 to 20 years).

Fueling headaches
Even if you get your hands on an NGV, fueling it can be a bit of an adventure. As of this past June, the DOE’s Office of Energy Efficiency and Renewable Energy listed only 835 CNG filling stations in the U. S., many not even open to the public.

If you’re not driving far, there’s always the option of refueling at home. But much of the available literature touts the Phill device, an NGV fueling station for home use that compresses and dispenses CNG from an existing supply line. It was manufactured by the FuelMaker Corp. of Toronto, but the company went bankrupt several years ago, apparently due to lack of demand. Its assets and technology were acquired last year by MTM/BRC, headquartered in Cherasco, Italy. The device is being sold domestically by Impco Technologies, Santa Ana, Calif., through distributors in 18 states. Delivery takes about 12 to 14 weeks, and installed cost runs approximately $7,000 to $7,500, according to a spokesman for ECO Friendly LLC, a distributor in Gibsonia, Pa.

CNG stations compress and store high-pressure gas, letting users fill the tank in about the same time as fueling a comparable gasoline-powered vehicle. At-home devices are usually time-fill systems with a smaller, less-expensive compressor and no storage tank. They typically refuel a vehicle overnight at rates of 0.5 to 1.0 GGE/hr.

In most cases, today’s NGVs are best suited for high-mileage vehicles such as buses, delivery trucks, and taxicabs. Limited range and fuel availability, plus high initial costs, generally make mass production of the vehicles unlikely in the near term, and restrict their use to centrally fueled and maintained fleets. But emissions pressures and rising oil costs may tilt the economics, leading to technology and infrastructure advances and more widespread use.

© 2010 Penton Media, Inc.

About the Author

Kenneth Korane

Ken Korane holds a B.S. Mechanical Engineering from The Ohio State University. In addition to serving as an editor at Machine Design until August 2015, his prior work experience includes product engineer at Parker Hannifin Corp. and mechanical design engineer at Euclid Inc. 

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