Auto Service World
Feature   October 1, 2000   by CARS Magazine

A Natural Alternative

Natural Gas could become a widespread motor fuel... if the infrastructure matches the technology

With gasoline currently priced upwards of 80 cents per litre, and a solid history of successful fleet use, why aren’t there more alternative fuel vehicles in consumers’ driveways? While there is a strong economic incentive at the pump, the infrastructure still needs work. Automakers are already offering factory dedicated natural gas and dual-fuel vehicles. Service procedures, training and certification are well within the capabilities of the average technician. Until the word is out, however, consumers will believe that they’re trapped by gasoline pricing driven by global oil policy. Natural gas is one possible alternative to gasoline. With an installed user base ranging from taxi operators to local utilities, and a supply so abundant that half of Canadian production is exported, natural gas would appear to be an excellent alternate fuel candidate.

Lower cost, cleaner emissions

Natural gas as a motor fuel makes sense for two fundamental reasons: cost and lower exhaust emissions. Cost is a complex issue, both because of the nature of the gaseous fuel and the regulatory/tax environment. On an energy equivalent basis, natural gas in Canada averages at approximately 60 percent of the cost of gasoline, although users generally experience a slight power loss. The economics of NGV’s, however, are dominated by vehicle conversion costs. A typical dual-fuel (gasoline and NG) conversion currently costs $3500 to $4000, depending on model, a premium that makes conversion not cost effective for many drivers. Fleet owners and individuals with long commutes, however, can see a reasonable payback, especially if averaged against rising gasoline prices. Can the consumer be convinced to pay the price premium for NG capability? Honda and Toyota have both launched gas-electric hybrids which carry even higher price premiums than NG conversion when compared to similar conventional models, and both are optimistic that widespread consumer acceptance of the new technology will allow mass production to lower the per unit cost. Natural gas vehicles are also available from domestic OEM’s, both as dual-fuel and dedicated NGV’s, although sales are targeted toward the fleet market. Are the savings sufficient to generate the ‘critical mass” necessary for NGV sales to take off? That depends on world oil pricing, consumer acceptance of new automotive technologies, and the willingness of auto manufacturers and natural gas suppliers to partner, allowing the consumer to purchase turnkey vehicle/home refuelling systems. Deregulation in the energy industry means more consumer choices in natural gas supply, with consumers in major markets able to choose between multiple suppliers. If natural gas marketing evolves into an environment where homeowners regularly negotiate fixed price supply contracts, the ability to lock in motor fuel pricing over the term of the contract could be an added appeal, especially if world oil pricing becomes volatile. Natural gas prices do rise as oil prices climb, but historically have remained stable at approximately 40 percent of gasoline on a volume-equivalent basis.

While cost is a complex issue with alternative fuels, the environmental benefits of natural gas vehicles (NGV’s) are great. Nox reductions average at 77 percent compared to gasoline-powered vehicles, carbon monoxide (CO) is reduced 75 to 95 percent, and ozone-forming hydrocarbons (HC) are reduced by 85 to 90 percent. And because NGV’s use closed fuel systems, evaporative emissions are essentially zero, both while driving and during refuelling.

A workable technology

NGV technology isn’t new; natural gas has been used in Italy since the 1920’s, and Canadian experience dates to the ’40’s, but the technical breakthrough which may lead to widespread adoption of the technology occurred in the ’80’s and ’90’s, with the advent of computer control and EFI. Previous conversions of carburetted vehicles used simple demand-feed fuel air mixer technology aided by engine coolant temperature regulation and mechanical pressure regulation. Although the systems worked well, dual fuel capability was difficult and expensive to engineer, and fine control over the combustion process was almost impossible given the wide range of operating RPM and load in an automotive application.

ECM and fuel injection technology changed the picture by splitting the fuel delivery pathway between the throttle body and the lower intake manifold. A typical system uses a 3000 psi cylinder supply which is regulated to 20 psi for delivery to an intake manifold mounted mixer. The mixer delivers the air/fuel mixture through the throttle body to the intake ports. Other systems inject the gas directly into the combustion chambers without using a gas/air mixer. Direct inject systems allow smooth NG/gasoline changeover in dual-fuel vehicles. The other advantage of the new technology is the availability of OE engine sensors to allow an on-board computer to optimize fuel flow and ignition timing. For successful dual-fuel conversions, ignition timing adaptability is crucial because of the combustion properties of natural gas. With an octane rating of approximately 130, natural gas systems need large amounts of timing advance, which must be reduced to conventional curves for gasoline operation. OE electronic distributor and distributorless ignition systems simplify the conversion by allowing the conversion kit ECU to “remap” timing curves for natural gas operation while retaining gasoline capability.

With an octane rating of 130, some or all of the power loss associated with NG operation can be regained by higher compression, although only dedicated engines can take full advantage of compression ratios higher than 10 to one, at least if pump gasoline capability is needed. The trend toward higher compression in modern gasoline engines, however, means that dual-fuel installations perform almost imperceptibly in normal driving. Natural gas is a “dry” fuel, so hardened valve seats are a common modification. As modern cars become more space efficient, cylinder placement is an issue, especially in dual fuel vehicles. Smaller vehicles lose considerable trunk capacity, especially with additional cylinders for extended range. Light trucks and large sedans such as Ford’s Crown Victoria, however, give up little volume.

Refuelling involves no technology new to anyone familiar with propane, and “quick fill” dispensing from natural gas refuelling stations takes from three to seven minutes. Home refuelling appliances can fill a vehicle in five to eight hours. Home refuelling has the added advantage of allowing the vehicle to begin the day with a full fuel load, reducing the inconvenience of the range limitation of NGV’s or the need for extended range tanks.

Safety is a non-issue, since statistics show no additional risk associated with NGV’s despite their 2000 to 3000 psi cylinder pressures. NGV safety is based on fail-safe cylinder and fuel system engineering combined with technician training and regular vehicle inspection.

Where’s the infrastructure?

“Infrastructure”, or more accurately the lack of it, has killed past alternate fuel initiatives. The combination of short vehicle range and few refuelling stations has dissuaded consumers from purchasing vehicles that can’t be used outside a local service region. NGV fill facilities are concentrated in B.C.’s lower mainland, the Calgary-Edmonton region, and southern Ontario, although current Natural Resources Canada estimates place the number of small refuelling appliances at 2000 and growing. If home appliance sales can be affordably rolled into the NG vehicle purchase, dedicated NGV’s could become popular in commuter regions and as a second family vehicle, although the majority of light-duty conversions are bi-fuel, at an average cost of between $3500 to $4000. 1997 and newer aftermarket vehicle conversions are eligible for a $500 contribution from Natural Resources Canada’s Natural Gas for Vehicles Program. Two thousand dollars is available to buyers of new dedicated or dual-fuel vehicles until January 31, 2002. To qualify, the vehic
les must be registered in a region served by Alberta natural gas. Program grants are administered by local natural gas companies. Funding of up to $25,000 is also available for vehicle refuelling stations.

Will incentives and high gasoline prices be enough? Much depends on global oil pricing and the emergence of new alternate energy technologies such as fuel cells. Fuel cells can run on natural gas, but hydrogen is the ultimate fuel. It can be produced by electrolysis of water either centrally or in home-based appliances. Ford is currently evaluating hydrogen fuel appliance prototypes from Toronto-based Stuart Energy Systems, with a long-term goal of developing home fuel appliances in time for the production of hydrogen fuel cell vehicles. While hydrogen may be a decade in the future, natural gas technology is mature and reliable.

If NG vehicles (or other alternate fuels) become truly popular, however, it is possible that both Federal and Provincial governments may impose some of the tax burden already felt at gasoline pumps, reducing the cost-effectiveness of NGV’s. To reach a popular critical mass, automakers, all three levels of government as well as the gas industry will have to create both awareness and additional incentives to wean consumers from gasoline. SSGM

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